Neurology

Two new large international studies have found relatively low rates of stroke in patients hospitalized with COVID-19. One study showed a stroke rate of 2.2% among patients with COVID-19 admitted to intensive care in 52 different countries. Another found a stroke rate of 1.48% in patients hospitalized with COVID-19 from 70 different countries. These researchers also found a reduction in stroke presentations and stroke care during the pandemic.

Both studies will be presented at the American Academy of Neurology’s 2021 annual meeting.

“Stroke has been a known serious complication of COVID-19, with some studies reporting a higher-than-expected occurrence, especially in young people,” said coauthor of the intensive care study, Jonathon Fanning, MBBS, PhD, University of Queensland, Brisbane, Australia.

“However, among the sickest of COVID patients – those admitted to an ICU – our research found that stroke was not a common complication and that ischemic stroke did not increase the risk of death,” he added.
 

Hemorrhagic stroke more common?

In this study, researchers analyzed a database of 2,699 patients who were admitted to the intensive care unit with COVID-19 in 52 countries and found that 59 of these patients (2.2%) subsequently sustained a stroke. 

Most of the strokes identified in this cohort were hemorrhagic (46%), with 32% being ischemic and 22% unspecified. Hemorrhagic stroke was associated with a fivefold increased risk for death compared with patients who did not have a stroke. Of those with a hemorrhagic stroke, 72% died, but only 15% died of the stroke. Rather, multiorgan failure was the leading cause of death.

There was no association between ischemic stroke and mortality.

“There is scarce research on new-onset stroke complicating ICU admissions, and many of the limitations of assessing stroke in ICU populations confound the true values and result in variability in reported incidence anywhere from a 1%-4% incidence,” Dr. Fanning said. 

He noted that a  large Korean study had shown a 1.2% rate of stroke in patients without COVID admitted to non-neurologic ICUs. “In light of this, I think this 2% is higher than we would expect in a general ICU population, but in the context of earlier reports of COVID-19–associated risk for stroke, this figure is actually somewhat reassuring,” Dr. Fanning said.  

Asked how this study compared with the large American Heart Association study recently reported that showed an overall rate of ischemic stroke of 0.75%, Dr. Fanning said the two studies reported on different populations, which makes them difficult to compare.

“Our study specifically reports on new-onset stroke complicating ICU admission,” he noted. “The AHA study is a large study of all patients admitted to hospital, but both studies identified less than previous estimates of COVID-related stroke.”
 

Largest sample to date  

The other study, which includes 119,967 COVID-19 hospitalizations and represents the largest sample reporting the concomitant diagnoses of stroke and SARS-CoV-2 infection to date, was presented at the AAN meeting by Thanh N. Nguyen, MD, a professor at Boston University.

This study has also been published online in Neurology, with first author Raul G. Nogueira, MD, Emory University, Atlanta.  

In this international observational, retrospective study across 6 continents, 70 countries, and 457 stroke centers, there was a 1.48% stroke rate across 119,967 COVID-19 hospitalizations. SARS-CoV-2 infection was noted in 3.3% (1,722) of all stroke admissions, which numbered 52,026.

The researchers identified stroke diagnoses by the International Classification of Diseases, 10th revision, codes and/or classifications in stroke center databases, and rates of stroke hospitalizations and numbers of patients receiving thrombolysis were compared between the first 4 months of the pandemic (March to June 2020) compared with two control 4-month periods.
 

Global decline in stroke care during pandemic

Results showed a global decline in the number of stroke patients admitted to the hospital as well as acute stroke treatments, such as thrombolysis, during the first wave of the COVID-19 pandemic. The researchers found that there were 91,373 stroke admissions in the 4 months immediately before the pandemic, compared with 80,894 admissions during the first 4 pandemic months, representing an 11.5% decline.

They also report that 13,334 stroke patients received intravenous thrombolysis in the 4 months preceding the pandemic, compared with 11,570 during the first 4 pandemic months, representing a 13.2% drop.

Interhospital transfers after thrombolysis for a higher level of stroke care decreased from 1,337 before the pandemic to 1,178 during the pandemic, a reduction of 11.9%.  

There were greater declines in primary compared with comprehensive stroke centers for stroke hospitalizations (change, –17.3% vs. –10.3%) and for the number of patients receiving thrombolysis (change, –15.5% vs. –12.6%).

The volume of stroke hospitalizations increased by 9.5% in the two later pandemic months (May, June) versus the two earlier months (March, April), with greater recovery in hospitals with lower COVID-19 hospitalization volume, high-volume stroke centers, and comprehensive stroke centers.

Dr. Nguyen suggested that reasons for the reductions in these stroke numbers at the beginning of the pandemic could include a reduction in stroke risk due to a reduction of exposure to other viral infections or patients not presenting to the hospital for fear of contracting the coronavirus.

The higher recovery of stroke volume in high-volume stroke centers and comprehensive stroke centers may represent patients with higher needs – those having more severe strokes – seeking care more frequently than those with milder symptoms, she noted.

“Preserving access to stroke care and emergency stroke care amidst a pandemic is as important as educating patients on the importance of presenting to the hospital in the event of stroke-like symptoms,” Dr. Nguyen concluded.

“We continue to advocate that if a patient has stroke-like symptoms, such as loss of speech, strength, vision, or balance, it is important for the patient to seek medical care as an emergency, as there are treatments that can improve a patient’s ability to recover from disabling stroke in earlier rather than later time windows,” she added.

In the publication, the authors wrote, “Our results concur with other recent reports on the collateral effects of the COVID-19 pandemic on stroke systems of care,” but added that “this is among the first descriptions of the change at a global level, including primary and comprehensive stroke centers.”

They said that hospital access related to high COVID-19 burden was unlikely a factor because the decline was seen in centers with a few or no patients with COVID-19. They suggested that patient fear of contracting coronavirus may have played a role, along with a decrease in presentation of transient ischemic attacks, mild strokes, or moderate strokes, and physical distancing measures may have prevented the timely witnessing of a stroke.

A version of this article first appeared on Medscape.com.

Two new large international studies have found relatively low rates of stroke in patients hospitalized with COVID-19. One study showed a stroke rate of 2.2% among patients with COVID-19 admitted to intensive care in 52 different countries. Another found a stroke rate of 1.48% in patients hospitalized with COVID-19 from 70 different countries. These researchers also found a reduction in stroke presentations and stroke care during the pandemic.

Both studies will be presented at the American Academy of Neurology’s 2021 annual meeting.

“Stroke has been a known serious complication of COVID-19, with some studies reporting a higher-than-expected occurrence, especially in young people,” said coauthor of the intensive care study, Jonathon Fanning, MBBS, PhD, University of Queensland, Brisbane, Australia.

“However, among the sickest of COVID patients – those admitted to an ICU – our research found that stroke was not a common complication and that ischemic stroke did not increase the risk of death,” he added.
 

Hemorrhagic stroke more common?

In this study, researchers analyzed a database of 2,699 patients who were admitted to the intensive care unit with COVID-19 in 52 countries and found that 59 of these patients (2.2%) subsequently sustained a stroke. 

Most of the strokes identified in this cohort were hemorrhagic (46%), with 32% being ischemic and 22% unspecified. Hemorrhagic stroke was associated with a fivefold increased risk for death compared with patients who did not have a stroke. Of those with a hemorrhagic stroke, 72% died, but only 15% died of the stroke. Rather, multiorgan failure was the leading cause of death.

There was no association between ischemic stroke and mortality.

“There is scarce research on new-onset stroke complicating ICU admissions, and many of the limitations of assessing stroke in ICU populations confound the true values and result in variability in reported incidence anywhere from a 1%-4% incidence,” Dr. Fanning said. 

He noted that a  large Korean study had shown a 1.2% rate of stroke in patients without COVID admitted to non-neurologic ICUs. “In light of this, I think this 2% is higher than we would expect in a general ICU population, but in the context of earlier reports of COVID-19–associated risk for stroke, this figure is actually somewhat reassuring,” Dr. Fanning said.  

Asked how this study compared with the large American Heart Association study recently reported that showed an overall rate of ischemic stroke of 0.75%, Dr. Fanning said the two studies reported on different populations, which makes them difficult to compare.

“Our study specifically reports on new-onset stroke complicating ICU admission,” he noted. “The AHA study is a large study of all patients admitted to hospital, but both studies identified less than previous estimates of COVID-related stroke.”
 

Largest sample to date  

The other study, which includes 119,967 COVID-19 hospitalizations and represents the largest sample reporting the concomitant diagnoses of stroke and SARS-CoV-2 infection to date, was presented at the AAN meeting by Thanh N. Nguyen, MD, a professor at Boston University.

This study has also been published online in Neurology, with first author Raul G. Nogueira, MD, Emory University, Atlanta.  

In this international observational, retrospective study across 6 continents, 70 countries, and 457 stroke centers, there was a 1.48% stroke rate across 119,967 COVID-19 hospitalizations. SARS-CoV-2 infection was noted in 3.3% (1,722) of all stroke admissions, which numbered 52,026.

The researchers identified stroke diagnoses by the International Classification of Diseases, 10th revision, codes and/or classifications in stroke center databases, and rates of stroke hospitalizations and numbers of patients receiving thrombolysis were compared between the first 4 months of the pandemic (March to June 2020) compared with two control 4-month periods.
 

Global decline in stroke care during pandemic

Results showed a global decline in the number of stroke patients admitted to the hospital as well as acute stroke treatments, such as thrombolysis, during the first wave of the COVID-19 pandemic. The researchers found that there were 91,373 stroke admissions in the 4 months immediately before the pandemic, compared with 80,894 admissions during the first 4 pandemic months, representing an 11.5% decline.

They also report that 13,334 stroke patients received intravenous thrombolysis in the 4 months preceding the pandemic, compared with 11,570 during the first 4 pandemic months, representing a 13.2% drop.

Interhospital transfers after thrombolysis for a higher level of stroke care decreased from 1,337 before the pandemic to 1,178 during the pandemic, a reduction of 11.9%.  

There were greater declines in primary compared with comprehensive stroke centers for stroke hospitalizations (change, –17.3% vs. –10.3%) and for the number of patients receiving thrombolysis (change, –15.5% vs. –12.6%).

The volume of stroke hospitalizations increased by 9.5% in the two later pandemic months (May, June) versus the two earlier months (March, April), with greater recovery in hospitals with lower COVID-19 hospitalization volume, high-volume stroke centers, and comprehensive stroke centers.

Dr. Nguyen suggested that reasons for the reductions in these stroke numbers at the beginning of the pandemic could include a reduction in stroke risk due to a reduction of exposure to other viral infections or patients not presenting to the hospital for fear of contracting the coronavirus.

The higher recovery of stroke volume in high-volume stroke centers and comprehensive stroke centers may represent patients with higher needs – those having more severe strokes – seeking care more frequently than those with milder symptoms, she noted.

“Preserving access to stroke care and emergency stroke care amidst a pandemic is as important as educating patients on the importance of presenting to the hospital in the event of stroke-like symptoms,” Dr. Nguyen concluded.

“We continue to advocate that if a patient has stroke-like symptoms, such as loss of speech, strength, vision, or balance, it is important for the patient to seek medical care as an emergency, as there are treatments that can improve a patient’s ability to recover from disabling stroke in earlier rather than later time windows,” she added.

In the publication, the authors wrote, “Our results concur with other recent reports on the collateral effects of the COVID-19 pandemic on stroke systems of care,” but added that “this is among the first descriptions of the change at a global level, including primary and comprehensive stroke centers.”

They said that hospital access related to high COVID-19 burden was unlikely a factor because the decline was seen in centers with a few or no patients with COVID-19. They suggested that patient fear of contracting coronavirus may have played a role, along with a decrease in presentation of transient ischemic attacks, mild strokes, or moderate strokes, and physical distancing measures may have prevented the timely witnessing of a stroke.

A version of this article first appeared on Medscape.com.

Two new large international studies have found relatively low rates of stroke in patients hospitalized with COVID-19. One study showed a stroke rate of 2.2% among patients with COVID-19 admitted to intensive care in 52 different countries. Another found a stroke rate of 1.48% in patients hospitalized with COVID-19 from 70 different countries. These researchers also found a reduction in stroke presentations and stroke care during the pandemic.

Both studies will be presented at the American Academy of Neurology’s 2021 annual meeting.

“Stroke has been a known serious complication of COVID-19, with some studies reporting a higher-than-expected occurrence, especially in young people,” said coauthor of the intensive care study, Jonathon Fanning, MBBS, PhD, University of Queensland, Brisbane, Australia.

“However, among the sickest of COVID patients – those admitted to an ICU – our research found that stroke was not a common complication and that ischemic stroke did not increase the risk of death,” he added.
 

Hemorrhagic stroke more common?

In this study, researchers analyzed a database of 2,699 patients who were admitted to the intensive care unit with COVID-19 in 52 countries and found that 59 of these patients (2.2%) subsequently sustained a stroke. 

Most of the strokes identified in this cohort were hemorrhagic (46%), with 32% being ischemic and 22% unspecified. Hemorrhagic stroke was associated with a fivefold increased risk for death compared with patients who did not have a stroke. Of those with a hemorrhagic stroke, 72% died, but only 15% died of the stroke. Rather, multiorgan failure was the leading cause of death.

There was no association between ischemic stroke and mortality.

“There is scarce research on new-onset stroke complicating ICU admissions, and many of the limitations of assessing stroke in ICU populations confound the true values and result in variability in reported incidence anywhere from a 1%-4% incidence,” Dr. Fanning said. 

He noted that a  large Korean study had shown a 1.2% rate of stroke in patients without COVID admitted to non-neurologic ICUs. “In light of this, I think this 2% is higher than we would expect in a general ICU population, but in the context of earlier reports of COVID-19–associated risk for stroke, this figure is actually somewhat reassuring,” Dr. Fanning said.  

Asked how this study compared with the large American Heart Association study recently reported that showed an overall rate of ischemic stroke of 0.75%, Dr. Fanning said the two studies reported on different populations, which makes them difficult to compare.

“Our study specifically reports on new-onset stroke complicating ICU admission,” he noted. “The AHA study is a large study of all patients admitted to hospital, but both studies identified less than previous estimates of COVID-related stroke.”
 

Largest sample to date  

The other study, which includes 119,967 COVID-19 hospitalizations and represents the largest sample reporting the concomitant diagnoses of stroke and SARS-CoV-2 infection to date, was presented at the AAN meeting by Thanh N. Nguyen, MD, a professor at Boston University.

This study has also been published online in Neurology, with first author Raul G. Nogueira, MD, Emory University, Atlanta.  

In this international observational, retrospective study across 6 continents, 70 countries, and 457 stroke centers, there was a 1.48% stroke rate across 119,967 COVID-19 hospitalizations. SARS-CoV-2 infection was noted in 3.3% (1,722) of all stroke admissions, which numbered 52,026.

The researchers identified stroke diagnoses by the International Classification of Diseases, 10th revision, codes and/or classifications in stroke center databases, and rates of stroke hospitalizations and numbers of patients receiving thrombolysis were compared between the first 4 months of the pandemic (March to June 2020) compared with two control 4-month periods.
 

Global decline in stroke care during pandemic

Results showed a global decline in the number of stroke patients admitted to the hospital as well as acute stroke treatments, such as thrombolysis, during the first wave of the COVID-19 pandemic. The researchers found that there were 91,373 stroke admissions in the 4 months immediately before the pandemic, compared with 80,894 admissions during the first 4 pandemic months, representing an 11.5% decline.

They also report that 13,334 stroke patients received intravenous thrombolysis in the 4 months preceding the pandemic, compared with 11,570 during the first 4 pandemic months, representing a 13.2% drop.

Interhospital transfers after thrombolysis for a higher level of stroke care decreased from 1,337 before the pandemic to 1,178 during the pandemic, a reduction of 11.9%.  

There were greater declines in primary compared with comprehensive stroke centers for stroke hospitalizations (change, –17.3% vs. –10.3%) and for the number of patients receiving thrombolysis (change, –15.5% vs. –12.6%).

The volume of stroke hospitalizations increased by 9.5% in the two later pandemic months (May, June) versus the two earlier months (March, April), with greater recovery in hospitals with lower COVID-19 hospitalization volume, high-volume stroke centers, and comprehensive stroke centers.

Dr. Nguyen suggested that reasons for the reductions in these stroke numbers at the beginning of the pandemic could include a reduction in stroke risk due to a reduction of exposure to other viral infections or patients not presenting to the hospital for fear of contracting the coronavirus.

The higher recovery of stroke volume in high-volume stroke centers and comprehensive stroke centers may represent patients with higher needs – those having more severe strokes – seeking care more frequently than those with milder symptoms, she noted.

“Preserving access to stroke care and emergency stroke care amidst a pandemic is as important as educating patients on the importance of presenting to the hospital in the event of stroke-like symptoms,” Dr. Nguyen concluded.

“We continue to advocate that if a patient has stroke-like symptoms, such as loss of speech, strength, vision, or balance, it is important for the patient to seek medical care as an emergency, as there are treatments that can improve a patient’s ability to recover from disabling stroke in earlier rather than later time windows,” she added.

In the publication, the authors wrote, “Our results concur with other recent reports on the collateral effects of the COVID-19 pandemic on stroke systems of care,” but added that “this is among the first descriptions of the change at a global level, including primary and comprehensive stroke centers.”

They said that hospital access related to high COVID-19 burden was unlikely a factor because the decline was seen in centers with a few or no patients with COVID-19. They suggested that patient fear of contracting coronavirus may have played a role, along with a decrease in presentation of transient ischemic attacks, mild strokes, or moderate strokes, and physical distancing measures may have prevented the timely witnessing of a stroke.

A version of this article first appeared on Medscape.com.

Exposure to epidural analgesia during labor did not show a link to a later diagnosis of autism spectrum disorder (ASD) in a population-based cohort study published April 19 in JAMA Pediatrics.

Though the initial analysis showed an association, adjustment for a wide range of demographic, medical, and birth factors eliminated the link. The authors note that their findings contrast with those of a cohort study in California published in the same journal last year.

“It is possible that residual confounding explains this positive association because key perinatal variables, including induction of labor, labor dystocia, and fetal distress, were not included as confounders in that study,” write Elizabeth Wall-Wieler, PhD, of the University of Manitoba in Winnipeg and her colleagues. “To limit potential bias from unmeasured confounders, we included the aforementioned variables within a wide set of potential confounders.”

The researchers analyzed linked datasets from all singleton infants born in a hospital from 2005 to 2016 in Manitoba, Canada, to compare use of epidurals during birth with diagnoses of ASD before 18 months of age. The four data sources included the Statistics Canada, Manitoba Education, Manitoba Families, and Manitoba Health, Seniors and Active Living, which includes the Manitoba Health Insurance Registry, Medical Services, Hospital Abstracts, and Drug Program Information Network. The researchers excluded women with cesarean deliveries because it was not possible to differentiate between scheduled and unscheduled cesarean deliveries.

Among 123,175 children born to mothers with an average age of 28 years, 38.2% had been exposed to epidural analgesia during their labor. Autism diagnoses occurred among 2.1% of those exposed to epidurals and 1.7% of those not exposed to epidurals. After the researchers controlled for a range of potential confounders, the difference became nonsignificant (hazard ratio, 1.08).

The adjusted analysis accounted for mother’s age; high school degree; marital status; neighborhood socioeconomic status; receipt of public assistance during pregnancy; and presence of diabetes, hypertension, anxiety, or depression in the year before the birth. Other covariates included in the adjustment included the following pregnancy factors: “parity, gestational diabetes, gestational hypertension or preeclampsia, self-reported and diagnosed drug use, smoking, alcohol use, premature rupture of membranes, antepartum hemorrhage, infection of the amniotic sac and membrane, urogenital infection, antenatal mental health hospitalization, hypothyroidism, benzodiazepine use, antidepressant use, and antiepileptic use.” The researchers also included birth year, labor induction or augmentation, labor dystocia, fetal distress or macrosomia, gestational age at birth, the infant’s sex, and hospital type.

“There were substantial differences in maternal sociodemographic, preexisting, pregnancy-related, and birth-specific covariates between births who were exposed vs. nonexposed to epidural labor analgesia,” the authors report. “For example, births exposed to epidural labor analgesia were more likely to be nulliparous, have premature rupture of membranes, antepartum hemorrhage, induction of labor, augmentation of labor, and fetal distress.”

To take family history of ASD into account, the researchers also compared siblings who were and were not exposed to an epidural during labor: 80,459 children in the cohort had at least one sibling in it as well. The researchers still found no association between use of an epidural and a subsequent autism diagnosis (HR, 0.97). The authors conducted several sensitivity analyses for first-born children, those with two or more diagnostic codes for ASD on different days, and women with missing data on high school completion or marital status who delivered at 37 weeks of gestation or later; these results consistently showed no association between epidurals and ASD.

The findings are important but unsurprising, said Scott M. Myers, MD, a neurodevelopmental pediatrician and associate professor at the Geisinger Commonwealth School of Medicine’s Autism & Developmental Medicine Institute in Scranton, Pa. Dr. Myers, who was not involved in the study, said it was strengthened by the inclusion of a wide range of covariates and multiple sensitivity analyses.

“It confirms the suspicion of many experts who were skeptical of the association reported previously, that the small increase in ASD in offspring of mothers who had epidural labor analgesia was likely attributable to other factors that differed substantially between the exposed and unexposed groups,” Dr. Myers said in an interview. “The plausibility of exposure to epidural analgesia in labor having a large effect on ASD risk and accounting for changes in ASD prevalence over time is low.”

It’s possible to hypothesize about subgroups that are genetically susceptible to certain environmental risk factors, including epidurals, but such an association should show up in epidemiological research if the subgroup is large enough.

“For example, epidural labor analgesia can prolong labor, and if it were a significant risk factor for ASD, one might expect that longer labor would have been demonstrated to be associated with increased ASD risk, but this has been examined and is not the case,” he said. He also noted that other perinatal factors previously linked to ASD, such as cesarean delivery, may result from a shared factor that affects risk of both ASD and cesarean delivery.

“Although there haven’t been enough systematic postmortem brain studies to be certain that the findings are generalizable, the most consistent neuropathological findings associated with ASD clearly arise long before birth,”Dr. Myers said. “The information I would provide to a concerned pregnant mother is that the current weight of the evidence does not suggest an association between epidural analgesia in labor and increased likelihood of ASD in offspring, much less a causal association.”

Clay Jones, MD, a hospitalist specializing in neonatal-perinatal medicine at Newton (Mass.)–Wellesley Hospital, was not involved in the research and offered a similar assessment of the findings.

“Our understanding of autism is that it is more of a genetic condition which interferes with the organization of brain architecture, so the evidence for any environmental cause would need to be robust for it to change medical practice or our recommendations to the general public,” Dr. Jones said in an interview. Compared to the previous California study, “this new research is larger and better accounts for confounding variables that might increase the risk of a child eventually being diagnosed with autism,” he said.

While recognizing the value in conducting studies to uncover any potential environmental factors contributing to autism diagnoses, Dr. Jones also addressed science communication challenges related to this research.

“While many of these studies are valid early efforts at honing in on potential risk factors, they can be overhyped and lead to increased patient anxiety and potentially harmful changes in behavior,” Dr. Jones said. “There is already a significant amount of pressure for many women to avoid certain safe and effective pain reduction strategies during labor, such as epidural labor analgesia. This pressure is often based on misunderstandings of the risks, pseudoscientific beliefs regarding the benefits of so-called ‘natural childbirth,’ and blatant misogyny. I hope that this new study helps to reassure women that it is okay to request to be more comfortable during their labor experience with the help of epidural labor analgesia.”

The authors of the study also noted the benefits of epidural use during labor.

“It is recognized as the most effective method of providing labor analgesia,” they write. In addition, “the presence of an indwelling epidural catheter allows epidural anesthesia to be administered for an unplanned (intrapartum) cesarean delivery, thus secondarily avoiding any maternal complications or fetal exposure from general anesthesia.”

JAMA Pediatrics editor Dimitri A. Christakis, MD, MPH, wrote his second-ever Editor’s Note about this topic after the journal published two similar studies with different conclusions.

“Because there will never be experimental studies of environmental exposures, we are left with imperfect observational studies that are always at risk for residual confounding, especially when observed effect sizes are small,” Dr. Christakis writes. “Science is an imperfect and iterative process, and our responsibility as journal editors is to manage the process as best we can. Publishing two conflicting studies in such a short time frame serves as testament that we recognize the process for what it is.” His personal opinion is that any association has yet to be definitively established but that the journal will publish the study if a more definitive one is done.

In considering potentially contributing environmental risk factors to ASD, Gillian E. Hanley, PhD, of the University of British Columbia in Vancouver and two colleagues write that “meta-analyses have been unable to identify a single perinatal and neonatal factor associated with ASD risk, although some evidence suggested that exposure to a broad class of conditions such as fetal presentation, umbilical-cord complications, fetal distress, or multiple births, reflecting compromised neonatal health, may increase risk.”

Yet, they add, these studies are inconsistent in their effect size, likely because of differences in study methodology, comparison groups, sample size, diagnostic criteria, and exposure assessment.

“Thus, we continue to ask questions about whether biologically plausible associations exist or whether associations reflect residual confounding related to yet-to-be-determined maternal genetic or environmental factors,” Dr. Hanley and her colleagues write. They discuss precise differences between the California and Manitoba studies and the inevitability of selection bias since people who choose an epidural will differ in other ways from those who don’t.

“Epidural labor analgesia is an extremely effective approach to obstetric analgesia, and we have a collective responsibility to understand whether it is a safe option that sets a healthy developmental pathway well into childhood,” Dr. Hanley and her colleagues conclude. “Women have the right to make a truly informed choice about their pain relief during labor.”

The research was funded by the Canadian Institutes of Health. One author reported receiving personal fees or grants from Aetion, Alosa Foundation, Lilly, GSK, Pacira, and Takeda. No other authors had disclosures. Dr. Jones, Dr. Myers, and the editorial authors had no disclosures.

Exposure to epidural analgesia during labor did not show a link to a later diagnosis of autism spectrum disorder (ASD) in a population-based cohort study published April 19 in JAMA Pediatrics.

Though the initial analysis showed an association, adjustment for a wide range of demographic, medical, and birth factors eliminated the link. The authors note that their findings contrast with those of a cohort study in California published in the same journal last year.

“It is possible that residual confounding explains this positive association because key perinatal variables, including induction of labor, labor dystocia, and fetal distress, were not included as confounders in that study,” write Elizabeth Wall-Wieler, PhD, of the University of Manitoba in Winnipeg and her colleagues. “To limit potential bias from unmeasured confounders, we included the aforementioned variables within a wide set of potential confounders.”

The researchers analyzed linked datasets from all singleton infants born in a hospital from 2005 to 2016 in Manitoba, Canada, to compare use of epidurals during birth with diagnoses of ASD before 18 months of age. The four data sources included the Statistics Canada, Manitoba Education, Manitoba Families, and Manitoba Health, Seniors and Active Living, which includes the Manitoba Health Insurance Registry, Medical Services, Hospital Abstracts, and Drug Program Information Network. The researchers excluded women with cesarean deliveries because it was not possible to differentiate between scheduled and unscheduled cesarean deliveries.

Among 123,175 children born to mothers with an average age of 28 years, 38.2% had been exposed to epidural analgesia during their labor. Autism diagnoses occurred among 2.1% of those exposed to epidurals and 1.7% of those not exposed to epidurals. After the researchers controlled for a range of potential confounders, the difference became nonsignificant (hazard ratio, 1.08).

The adjusted analysis accounted for mother’s age; high school degree; marital status; neighborhood socioeconomic status; receipt of public assistance during pregnancy; and presence of diabetes, hypertension, anxiety, or depression in the year before the birth. Other covariates included in the adjustment included the following pregnancy factors: “parity, gestational diabetes, gestational hypertension or preeclampsia, self-reported and diagnosed drug use, smoking, alcohol use, premature rupture of membranes, antepartum hemorrhage, infection of the amniotic sac and membrane, urogenital infection, antenatal mental health hospitalization, hypothyroidism, benzodiazepine use, antidepressant use, and antiepileptic use.” The researchers also included birth year, labor induction or augmentation, labor dystocia, fetal distress or macrosomia, gestational age at birth, the infant’s sex, and hospital type.

“There were substantial differences in maternal sociodemographic, preexisting, pregnancy-related, and birth-specific covariates between births who were exposed vs. nonexposed to epidural labor analgesia,” the authors report. “For example, births exposed to epidural labor analgesia were more likely to be nulliparous, have premature rupture of membranes, antepartum hemorrhage, induction of labor, augmentation of labor, and fetal distress.”

To take family history of ASD into account, the researchers also compared siblings who were and were not exposed to an epidural during labor: 80,459 children in the cohort had at least one sibling in it as well. The researchers still found no association between use of an epidural and a subsequent autism diagnosis (HR, 0.97). The authors conducted several sensitivity analyses for first-born children, those with two or more diagnostic codes for ASD on different days, and women with missing data on high school completion or marital status who delivered at 37 weeks of gestation or later; these results consistently showed no association between epidurals and ASD.

The findings are important but unsurprising, said Scott M. Myers, MD, a neurodevelopmental pediatrician and associate professor at the Geisinger Commonwealth School of Medicine’s Autism & Developmental Medicine Institute in Scranton, Pa. Dr. Myers, who was not involved in the study, said it was strengthened by the inclusion of a wide range of covariates and multiple sensitivity analyses.

“It confirms the suspicion of many experts who were skeptical of the association reported previously, that the small increase in ASD in offspring of mothers who had epidural labor analgesia was likely attributable to other factors that differed substantially between the exposed and unexposed groups,” Dr. Myers said in an interview. “The plausibility of exposure to epidural analgesia in labor having a large effect on ASD risk and accounting for changes in ASD prevalence over time is low.”

It’s possible to hypothesize about subgroups that are genetically susceptible to certain environmental risk factors, including epidurals, but such an association should show up in epidemiological research if the subgroup is large enough.

“For example, epidural labor analgesia can prolong labor, and if it were a significant risk factor for ASD, one might expect that longer labor would have been demonstrated to be associated with increased ASD risk, but this has been examined and is not the case,” he said. He also noted that other perinatal factors previously linked to ASD, such as cesarean delivery, may result from a shared factor that affects risk of both ASD and cesarean delivery.

“Although there haven’t been enough systematic postmortem brain studies to be certain that the findings are generalizable, the most consistent neuropathological findings associated with ASD clearly arise long before birth,”Dr. Myers said. “The information I would provide to a concerned pregnant mother is that the current weight of the evidence does not suggest an association between epidural analgesia in labor and increased likelihood of ASD in offspring, much less a causal association.”

Clay Jones, MD, a hospitalist specializing in neonatal-perinatal medicine at Newton (Mass.)–Wellesley Hospital, was not involved in the research and offered a similar assessment of the findings.

“Our understanding of autism is that it is more of a genetic condition which interferes with the organization of brain architecture, so the evidence for any environmental cause would need to be robust for it to change medical practice or our recommendations to the general public,” Dr. Jones said in an interview. Compared to the previous California study, “this new research is larger and better accounts for confounding variables that might increase the risk of a child eventually being diagnosed with autism,” he said.

While recognizing the value in conducting studies to uncover any potential environmental factors contributing to autism diagnoses, Dr. Jones also addressed science communication challenges related to this research.

“While many of these studies are valid early efforts at honing in on potential risk factors, they can be overhyped and lead to increased patient anxiety and potentially harmful changes in behavior,” Dr. Jones said. “There is already a significant amount of pressure for many women to avoid certain safe and effective pain reduction strategies during labor, such as epidural labor analgesia. This pressure is often based on misunderstandings of the risks, pseudoscientific beliefs regarding the benefits of so-called ‘natural childbirth,’ and blatant misogyny. I hope that this new study helps to reassure women that it is okay to request to be more comfortable during their labor experience with the help of epidural labor analgesia.”

The authors of the study also noted the benefits of epidural use during labor.

“It is recognized as the most effective method of providing labor analgesia,” they write. In addition, “the presence of an indwelling epidural catheter allows epidural anesthesia to be administered for an unplanned (intrapartum) cesarean delivery, thus secondarily avoiding any maternal complications or fetal exposure from general anesthesia.”

JAMA Pediatrics editor Dimitri A. Christakis, MD, MPH, wrote his second-ever Editor’s Note about this topic after the journal published two similar studies with different conclusions.

“Because there will never be experimental studies of environmental exposures, we are left with imperfect observational studies that are always at risk for residual confounding, especially when observed effect sizes are small,” Dr. Christakis writes. “Science is an imperfect and iterative process, and our responsibility as journal editors is to manage the process as best we can. Publishing two conflicting studies in such a short time frame serves as testament that we recognize the process for what it is.” His personal opinion is that any association has yet to be definitively established but that the journal will publish the study if a more definitive one is done.

In considering potentially contributing environmental risk factors to ASD, Gillian E. Hanley, PhD, of the University of British Columbia in Vancouver and two colleagues write that “meta-analyses have been unable to identify a single perinatal and neonatal factor associated with ASD risk, although some evidence suggested that exposure to a broad class of conditions such as fetal presentation, umbilical-cord complications, fetal distress, or multiple births, reflecting compromised neonatal health, may increase risk.”

Yet, they add, these studies are inconsistent in their effect size, likely because of differences in study methodology, comparison groups, sample size, diagnostic criteria, and exposure assessment.

“Thus, we continue to ask questions about whether biologically plausible associations exist or whether associations reflect residual confounding related to yet-to-be-determined maternal genetic or environmental factors,” Dr. Hanley and her colleagues write. They discuss precise differences between the California and Manitoba studies and the inevitability of selection bias since people who choose an epidural will differ in other ways from those who don’t.

“Epidural labor analgesia is an extremely effective approach to obstetric analgesia, and we have a collective responsibility to understand whether it is a safe option that sets a healthy developmental pathway well into childhood,” Dr. Hanley and her colleagues conclude. “Women have the right to make a truly informed choice about their pain relief during labor.”

The research was funded by the Canadian Institutes of Health. One author reported receiving personal fees or grants from Aetion, Alosa Foundation, Lilly, GSK, Pacira, and Takeda. No other authors had disclosures. Dr. Jones, Dr. Myers, and the editorial authors had no disclosures.

Exposure to epidural analgesia during labor did not show a link to a later diagnosis of autism spectrum disorder (ASD) in a population-based cohort study published April 19 in JAMA Pediatrics.

Though the initial analysis showed an association, adjustment for a wide range of demographic, medical, and birth factors eliminated the link. The authors note that their findings contrast with those of a cohort study in California published in the same journal last year.

“It is possible that residual confounding explains this positive association because key perinatal variables, including induction of labor, labor dystocia, and fetal distress, were not included as confounders in that study,” write Elizabeth Wall-Wieler, PhD, of the University of Manitoba in Winnipeg and her colleagues. “To limit potential bias from unmeasured confounders, we included the aforementioned variables within a wide set of potential confounders.”

The researchers analyzed linked datasets from all singleton infants born in a hospital from 2005 to 2016 in Manitoba, Canada, to compare use of epidurals during birth with diagnoses of ASD before 18 months of age. The four data sources included the Statistics Canada, Manitoba Education, Manitoba Families, and Manitoba Health, Seniors and Active Living, which includes the Manitoba Health Insurance Registry, Medical Services, Hospital Abstracts, and Drug Program Information Network. The researchers excluded women with cesarean deliveries because it was not possible to differentiate between scheduled and unscheduled cesarean deliveries.

Among 123,175 children born to mothers with an average age of 28 years, 38.2% had been exposed to epidural analgesia during their labor. Autism diagnoses occurred among 2.1% of those exposed to epidurals and 1.7% of those not exposed to epidurals. After the researchers controlled for a range of potential confounders, the difference became nonsignificant (hazard ratio, 1.08).

The adjusted analysis accounted for mother’s age; high school degree; marital status; neighborhood socioeconomic status; receipt of public assistance during pregnancy; and presence of diabetes, hypertension, anxiety, or depression in the year before the birth. Other covariates included in the adjustment included the following pregnancy factors: “parity, gestational diabetes, gestational hypertension or preeclampsia, self-reported and diagnosed drug use, smoking, alcohol use, premature rupture of membranes, antepartum hemorrhage, infection of the amniotic sac and membrane, urogenital infection, antenatal mental health hospitalization, hypothyroidism, benzodiazepine use, antidepressant use, and antiepileptic use.” The researchers also included birth year, labor induction or augmentation, labor dystocia, fetal distress or macrosomia, gestational age at birth, the infant’s sex, and hospital type.

“There were substantial differences in maternal sociodemographic, preexisting, pregnancy-related, and birth-specific covariates between births who were exposed vs. nonexposed to epidural labor analgesia,” the authors report. “For example, births exposed to epidural labor analgesia were more likely to be nulliparous, have premature rupture of membranes, antepartum hemorrhage, induction of labor, augmentation of labor, and fetal distress.”

To take family history of ASD into account, the researchers also compared siblings who were and were not exposed to an epidural during labor: 80,459 children in the cohort had at least one sibling in it as well. The researchers still found no association between use of an epidural and a subsequent autism diagnosis (HR, 0.97). The authors conducted several sensitivity analyses for first-born children, those with two or more diagnostic codes for ASD on different days, and women with missing data on high school completion or marital status who delivered at 37 weeks of gestation or later; these results consistently showed no association between epidurals and ASD.

The findings are important but unsurprising, said Scott M. Myers, MD, a neurodevelopmental pediatrician and associate professor at the Geisinger Commonwealth School of Medicine’s Autism & Developmental Medicine Institute in Scranton, Pa. Dr. Myers, who was not involved in the study, said it was strengthened by the inclusion of a wide range of covariates and multiple sensitivity analyses.

“It confirms the suspicion of many experts who were skeptical of the association reported previously, that the small increase in ASD in offspring of mothers who had epidural labor analgesia was likely attributable to other factors that differed substantially between the exposed and unexposed groups,” Dr. Myers said in an interview. “The plausibility of exposure to epidural analgesia in labor having a large effect on ASD risk and accounting for changes in ASD prevalence over time is low.”

It’s possible to hypothesize about subgroups that are genetically susceptible to certain environmental risk factors, including epidurals, but such an association should show up in epidemiological research if the subgroup is large enough.

“For example, epidural labor analgesia can prolong labor, and if it were a significant risk factor for ASD, one might expect that longer labor would have been demonstrated to be associated with increased ASD risk, but this has been examined and is not the case,” he said. He also noted that other perinatal factors previously linked to ASD, such as cesarean delivery, may result from a shared factor that affects risk of both ASD and cesarean delivery.

“Although there haven’t been enough systematic postmortem brain studies to be certain that the findings are generalizable, the most consistent neuropathological findings associated with ASD clearly arise long before birth,”Dr. Myers said. “The information I would provide to a concerned pregnant mother is that the current weight of the evidence does not suggest an association between epidural analgesia in labor and increased likelihood of ASD in offspring, much less a causal association.”

Clay Jones, MD, a hospitalist specializing in neonatal-perinatal medicine at Newton (Mass.)–Wellesley Hospital, was not involved in the research and offered a similar assessment of the findings.

“Our understanding of autism is that it is more of a genetic condition which interferes with the organization of brain architecture, so the evidence for any environmental cause would need to be robust for it to change medical practice or our recommendations to the general public,” Dr. Jones said in an interview. Compared to the previous California study, “this new research is larger and better accounts for confounding variables that might increase the risk of a child eventually being diagnosed with autism,” he said.

While recognizing the value in conducting studies to uncover any potential environmental factors contributing to autism diagnoses, Dr. Jones also addressed science communication challenges related to this research.

“While many of these studies are valid early efforts at honing in on potential risk factors, they can be overhyped and lead to increased patient anxiety and potentially harmful changes in behavior,” Dr. Jones said. “There is already a significant amount of pressure for many women to avoid certain safe and effective pain reduction strategies during labor, such as epidural labor analgesia. This pressure is often based on misunderstandings of the risks, pseudoscientific beliefs regarding the benefits of so-called ‘natural childbirth,’ and blatant misogyny. I hope that this new study helps to reassure women that it is okay to request to be more comfortable during their labor experience with the help of epidural labor analgesia.”

The authors of the study also noted the benefits of epidural use during labor.

“It is recognized as the most effective method of providing labor analgesia,” they write. In addition, “the presence of an indwelling epidural catheter allows epidural anesthesia to be administered for an unplanned (intrapartum) cesarean delivery, thus secondarily avoiding any maternal complications or fetal exposure from general anesthesia.”

JAMA Pediatrics editor Dimitri A. Christakis, MD, MPH, wrote his second-ever Editor’s Note about this topic after the journal published two similar studies with different conclusions.

“Because there will never be experimental studies of environmental exposures, we are left with imperfect observational studies that are always at risk for residual confounding, especially when observed effect sizes are small,” Dr. Christakis writes. “Science is an imperfect and iterative process, and our responsibility as journal editors is to manage the process as best we can. Publishing two conflicting studies in such a short time frame serves as testament that we recognize the process for what it is.” His personal opinion is that any association has yet to be definitively established but that the journal will publish the study if a more definitive one is done.

In considering potentially contributing environmental risk factors to ASD, Gillian E. Hanley, PhD, of the University of British Columbia in Vancouver and two colleagues write that “meta-analyses have been unable to identify a single perinatal and neonatal factor associated with ASD risk, although some evidence suggested that exposure to a broad class of conditions such as fetal presentation, umbilical-cord complications, fetal distress, or multiple births, reflecting compromised neonatal health, may increase risk.”

Yet, they add, these studies are inconsistent in their effect size, likely because of differences in study methodology, comparison groups, sample size, diagnostic criteria, and exposure assessment.

“Thus, we continue to ask questions about whether biologically plausible associations exist or whether associations reflect residual confounding related to yet-to-be-determined maternal genetic or environmental factors,” Dr. Hanley and her colleagues write. They discuss precise differences between the California and Manitoba studies and the inevitability of selection bias since people who choose an epidural will differ in other ways from those who don’t.

“Epidural labor analgesia is an extremely effective approach to obstetric analgesia, and we have a collective responsibility to understand whether it is a safe option that sets a healthy developmental pathway well into childhood,” Dr. Hanley and her colleagues conclude. “Women have the right to make a truly informed choice about their pain relief during labor.”

The research was funded by the Canadian Institutes of Health. One author reported receiving personal fees or grants from Aetion, Alosa Foundation, Lilly, GSK, Pacira, and Takeda. No other authors had disclosures. Dr. Jones, Dr. Myers, and the editorial authors had no disclosures.

Myoclonus was diagnosed in about half of hospitalized COVID-19 patients who were evaluated for movement disorders, data from 50 cases show.

Abnormal movements often occur as complications from critical illness, and neurologic consultation can determine whether patients have experienced a seizure or stroke. However, restriction of bedside assessment in the wake of the COVID-19 pandemic increases the risk that abnormal movements will be missed, Jeffrey R. Clark and Eric M. Liotta, MD, of Northwestern University, Chicago, and colleagues wrote.

“Given the limited reports of abnormal movements in hospitalized COVID-19 patients and increased recognition of neurologic manifestations of COVID-19, we sought to examine the frequency and etiology of this finding as an indication of neurologic consultation,” they said.

In a study published in the Journal of the Neurological Sciences, the researchers reviewed data from the first 50 consecutive patients with COVID-19 symptoms who were hospitalized at a single center and underwent neurologic consultation between March 17, 2020, and May 18, 2020.

Overall, 11 patients (22.0%) of patients experienced abnormal movement, and all were admitted to the ICU within 7 days of meeting criteria for severe COVID-19. These patients included nine men and two women with an age range of 36-78 years. The most common comorbidities were obesity, hypertension, diabetes, chronic kidney disease, and coronary artery disease.

Myoclonus (generalized and focal) was the most common abnormal movement, and present in 6 of the 11 patients. Three cases were attributed to high-intensity sedation, and three to toxic-metabolic disturbances. In two patients, abnormal movements were attributed to focal seizures in the setting of encephalopathy, with focal facial twitching. An additional two patients experienced tremors; one showed an acute subdural hemorrhage on CT imaging. The second patient showed no sign of stroke or other abnormality on MRI and the tremor improved during the hospital stay. One patient who experienced abnormal high-amplitude nonrhythmic movements of the lower extremities was diagnosed with serotonin syndrome that resolved after discontinuing high-dose fentanyl.

The study findings were limited by several factors, including the small study population and limited availability of MRI, the researchers noted. Assessing severe COVID-19 cases in the ICU setting presents a challenge because of limited patient participation and the potentially confounding effects of sedation and mechanical ventilation.

However, the results highlight the importance of bedside consultation for neurologic evaluation to implement timely, directed treatments, the researchers said.

“A heightened awareness of abnormal eye movements, or subtle facial tremoring, may be the first steps in recognizing potentially dangerous neurologic manifestations,” and clinicians caring for patients with severe COVID-19 should be able to recognize abnormal movements and seek neurologic consultation when indicated, they emphasized.

The study was supported in part by grants to coauthors Nicholas J. Reish, MD, and Dr. Liotta from the National Institutes of Health. The researchers had no financial conflicts to disclose.

Myoclonus was diagnosed in about half of hospitalized COVID-19 patients who were evaluated for movement disorders, data from 50 cases show.

Abnormal movements often occur as complications from critical illness, and neurologic consultation can determine whether patients have experienced a seizure or stroke. However, restriction of bedside assessment in the wake of the COVID-19 pandemic increases the risk that abnormal movements will be missed, Jeffrey R. Clark and Eric M. Liotta, MD, of Northwestern University, Chicago, and colleagues wrote.

“Given the limited reports of abnormal movements in hospitalized COVID-19 patients and increased recognition of neurologic manifestations of COVID-19, we sought to examine the frequency and etiology of this finding as an indication of neurologic consultation,” they said.

In a study published in the Journal of the Neurological Sciences, the researchers reviewed data from the first 50 consecutive patients with COVID-19 symptoms who were hospitalized at a single center and underwent neurologic consultation between March 17, 2020, and May 18, 2020.

Overall, 11 patients (22.0%) of patients experienced abnormal movement, and all were admitted to the ICU within 7 days of meeting criteria for severe COVID-19. These patients included nine men and two women with an age range of 36-78 years. The most common comorbidities were obesity, hypertension, diabetes, chronic kidney disease, and coronary artery disease.

Myoclonus (generalized and focal) was the most common abnormal movement, and present in 6 of the 11 patients. Three cases were attributed to high-intensity sedation, and three to toxic-metabolic disturbances. In two patients, abnormal movements were attributed to focal seizures in the setting of encephalopathy, with focal facial twitching. An additional two patients experienced tremors; one showed an acute subdural hemorrhage on CT imaging. The second patient showed no sign of stroke or other abnormality on MRI and the tremor improved during the hospital stay. One patient who experienced abnormal high-amplitude nonrhythmic movements of the lower extremities was diagnosed with serotonin syndrome that resolved after discontinuing high-dose fentanyl.

The study findings were limited by several factors, including the small study population and limited availability of MRI, the researchers noted. Assessing severe COVID-19 cases in the ICU setting presents a challenge because of limited patient participation and the potentially confounding effects of sedation and mechanical ventilation.

However, the results highlight the importance of bedside consultation for neurologic evaluation to implement timely, directed treatments, the researchers said.

“A heightened awareness of abnormal eye movements, or subtle facial tremoring, may be the first steps in recognizing potentially dangerous neurologic manifestations,” and clinicians caring for patients with severe COVID-19 should be able to recognize abnormal movements and seek neurologic consultation when indicated, they emphasized.

The study was supported in part by grants to coauthors Nicholas J. Reish, MD, and Dr. Liotta from the National Institutes of Health. The researchers had no financial conflicts to disclose.

Myoclonus was diagnosed in about half of hospitalized COVID-19 patients who were evaluated for movement disorders, data from 50 cases show.

Abnormal movements often occur as complications from critical illness, and neurologic consultation can determine whether patients have experienced a seizure or stroke. However, restriction of bedside assessment in the wake of the COVID-19 pandemic increases the risk that abnormal movements will be missed, Jeffrey R. Clark and Eric M. Liotta, MD, of Northwestern University, Chicago, and colleagues wrote.

“Given the limited reports of abnormal movements in hospitalized COVID-19 patients and increased recognition of neurologic manifestations of COVID-19, we sought to examine the frequency and etiology of this finding as an indication of neurologic consultation,” they said.

In a study published in the Journal of the Neurological Sciences, the researchers reviewed data from the first 50 consecutive patients with COVID-19 symptoms who were hospitalized at a single center and underwent neurologic consultation between March 17, 2020, and May 18, 2020.

Overall, 11 patients (22.0%) of patients experienced abnormal movement, and all were admitted to the ICU within 7 days of meeting criteria for severe COVID-19. These patients included nine men and two women with an age range of 36-78 years. The most common comorbidities were obesity, hypertension, diabetes, chronic kidney disease, and coronary artery disease.

Myoclonus (generalized and focal) was the most common abnormal movement, and present in 6 of the 11 patients. Three cases were attributed to high-intensity sedation, and three to toxic-metabolic disturbances. In two patients, abnormal movements were attributed to focal seizures in the setting of encephalopathy, with focal facial twitching. An additional two patients experienced tremors; one showed an acute subdural hemorrhage on CT imaging. The second patient showed no sign of stroke or other abnormality on MRI and the tremor improved during the hospital stay. One patient who experienced abnormal high-amplitude nonrhythmic movements of the lower extremities was diagnosed with serotonin syndrome that resolved after discontinuing high-dose fentanyl.

The study findings were limited by several factors, including the small study population and limited availability of MRI, the researchers noted. Assessing severe COVID-19 cases in the ICU setting presents a challenge because of limited patient participation and the potentially confounding effects of sedation and mechanical ventilation.

However, the results highlight the importance of bedside consultation for neurologic evaluation to implement timely, directed treatments, the researchers said.

“A heightened awareness of abnormal eye movements, or subtle facial tremoring, may be the first steps in recognizing potentially dangerous neurologic manifestations,” and clinicians caring for patients with severe COVID-19 should be able to recognize abnormal movements and seek neurologic consultation when indicated, they emphasized.

The study was supported in part by grants to coauthors Nicholas J. Reish, MD, and Dr. Liotta from the National Institutes of Health. The researchers had no financial conflicts to disclose.

Cardiologists experienced in cardiac interventions can competently perform stroke thrombectomy after a short period of training, with outcomes comparable to those achieved by neuroradiology centers, a new study suggests.
 

“Using interventional cardiologists in this way will help address the huge unmet need for stroke thrombectomy that currently exists,” senior author Petr Widimsky, MD, said in an interview.

Although this may be a feasible way forward in Europe, there is strong opposition to such a proposal from U.S. neurointerventionalists.  

The study, published in the April 12 issue of JACC: Cardiovascular Interventions, describes the establishment of a stroke thrombectomy program in University Hospital Kralovske Vinohrady, a large tertiary hospital in Prague, Czech Republic.

The hospital did not have a neurointerventional program until 2012 when a joint program was started involving an experienced team of cardiologists, angiologists, and one interventional radiologist who trained the cardiologists on the thrombectomy procedure.

The current paper reports on the outcomes of the 333 patients with large vessel occlusion stroke treated under this program between October 2012 and December 2019.

The decision to perform catheter-based thrombectomy was made by a neurologist and was based on acute stroke clinical symptoms and CT angiographic findings.

Results show that functional clinical outcomes, assessed via the Modified Rankin Scale (mRS) score at 3 months, did not vary significantly across years 2012 to 2019, with a favorable outcome (mRS 0 to 2) achieved in 47.9% of patients.

Symptomatic intracerebral hemorrhage occurred in 19 patients (5.7%) and embolization in a new vascular territory occurred in 6 patients (1.8%), outcomes similar to those of neuroradiology centers.

The desired clinical results were achieved from the onset of the program, without any signs of a learning curve effect, they reported.

“These findings support the potential role of interventional cardiac cath labs in the treatment of acute stroke in regions where this therapy is not readily available due to the lack of neurointerventionalists,” the authors concluded.

“Our main message is that our results were excellent from the beginning,” Dr. Widimsky said. “When centers prepare properly, they can achieve excellent results from the beginning with cardiologists who are experienced in interventional procedures and who have spent sufficient time learning about the brain.”  

The authors noted that despite thrombectomy being an extremely beneficial treatment for severe stroke, many eligible patients remain untreated, largely because of a lack of neurointerventionalists in many regions worldwide. They estimate that about 15% of all stroke patients are eligible for thrombectomy but only around 2% of stroke patients in Europe actually receive such treatment.

Dr. Widimsky, an interventional cardiologist, first thought of the idea of using cardiologists to perform stroke thrombectomies after a good friend and colleague suffered a severe stroke in 2010.

“This made us realize that our hospital needed to be more active in the stroke field,” he said. “We decided that we needed to start doing stroke interventions.”

But the major problem was the lack of neurointerventionalists.

“There are not enough neurointerventionalists in Europe. Interventional cardiologists can perform thousands of procedures every year whereas a neurointerventionalist will at best perform hundreds a year. It is quicker and simpler to train the cardiologist to do it,” Dr. Widimsky said.  

They hired one neurointerventionalist to lead the program. “He was our tutor, he taught us his skills,” Dr. Widimsky said. “The cath lab is open 24/7, but if we only have one neurointerventionalist we cannot offer a 24/7 service for stroke thrombectomy. But if we merge with cardiology then we can,” he added.

Their hospital is a very busy center for myocardial infarction, percutaneous coronary intervention, and carotid stenting, he noted. “It is not difficult to make the step from that to stroke thrombectomy. Interventional cardiologists are used to performing carotid and coronary artery stenting. Stroke thrombectomy is a similar technique. The thrombectomy procedure is different from coronary angioplasty but it is not more difficult.  Actually, I think coronary angioplasty can be more difficult.”  

Dr. Widimsky explained that cardiologists need to learn about the brain anatomy and physiology and learn the stroke imaging techniques. “I spent 1 month in the U.S. learning stroke interventions working with simulators,” he said. “I think interventional cardiologists can learn what they need to know in about 6 months. I would recommend they should watch about 50 procedures and perform at least 25 under supervision.”

He said this model is the way forward and hopes it will become routine. Thrombectomy is “tremendously effective” in improving outcomes in severe strokes, with a number needed to treat (NNT) of just 2.6 to prevent long-term disability in one patient, he said, while other procedures can have NNTs of 50 or more.  

“But millions of patients with acute severe stroke are not getting this life-changing treatment,” he added. “We must do everything we can to make this service available to as many patients as possible.”

Dr. Widimsky acknowledges that there has been opposition to this idea from the neurointerventionalist professional bodies but this has lessened recently, at least in Europe. And a program that allows interventionalists with experience in extracranial carotid and vertebral endovascular procedures to “fast-track” technical training has now been proposed.

“There is an enormous unmet need for stroke thrombectomy in Europe, with some countries needing to increase the number of procedures done by 10 or 20 times. These include the U.K., Sweden, Italy, Spain, and Portugal. This cannot be done without cardiology,” Dr. Widimsky said.  
 

Editorial strongly supportive

An accompanying editorial strongly endorses the idea of using interdisciplinary teams to deliver high standard stroke care.

Marius Hornung, MD, and Horst Sievert, MD, from CardioVascular Center Frankfurt (Germany), point out that many experienced cardiologists are trained in performing carotid artery interventions and are therefore experienced in accessing the supra-aortic arteries.

Ted Bosworth/MDedge News

Opposition in the United States

Dr. Widimsky explained that this proposal may not be so applicable to the United States, where the need for more clinicians capable of performing stroke thrombectomies does not appear to be as critical, possibly because vascular neurosurgeons as well as neuroradiologists are qualified to undertake these procedures.

In an interview, J. Mocco, MD, director of the cerebrovascular center, department of neurological surgery, at Mount Sinai Health System, New York, confirmed that this was the case.

MDedge News

A version of this article first appeared on Medscape.com.

Cardiologists experienced in cardiac interventions can competently perform stroke thrombectomy after a short period of training, with outcomes comparable to those achieved by neuroradiology centers, a new study suggests.
 

“Using interventional cardiologists in this way will help address the huge unmet need for stroke thrombectomy that currently exists,” senior author Petr Widimsky, MD, said in an interview.

Although this may be a feasible way forward in Europe, there is strong opposition to such a proposal from U.S. neurointerventionalists.  

The study, published in the April 12 issue of JACC: Cardiovascular Interventions, describes the establishment of a stroke thrombectomy program in University Hospital Kralovske Vinohrady, a large tertiary hospital in Prague, Czech Republic.

The hospital did not have a neurointerventional program until 2012 when a joint program was started involving an experienced team of cardiologists, angiologists, and one interventional radiologist who trained the cardiologists on the thrombectomy procedure.

The current paper reports on the outcomes of the 333 patients with large vessel occlusion stroke treated under this program between October 2012 and December 2019.

The decision to perform catheter-based thrombectomy was made by a neurologist and was based on acute stroke clinical symptoms and CT angiographic findings.

Results show that functional clinical outcomes, assessed via the Modified Rankin Scale (mRS) score at 3 months, did not vary significantly across years 2012 to 2019, with a favorable outcome (mRS 0 to 2) achieved in 47.9% of patients.

Symptomatic intracerebral hemorrhage occurred in 19 patients (5.7%) and embolization in a new vascular territory occurred in 6 patients (1.8%), outcomes similar to those of neuroradiology centers.

The desired clinical results were achieved from the onset of the program, without any signs of a learning curve effect, they reported.

“These findings support the potential role of interventional cardiac cath labs in the treatment of acute stroke in regions where this therapy is not readily available due to the lack of neurointerventionalists,” the authors concluded.

“Our main message is that our results were excellent from the beginning,” Dr. Widimsky said. “When centers prepare properly, they can achieve excellent results from the beginning with cardiologists who are experienced in interventional procedures and who have spent sufficient time learning about the brain.”  

The authors noted that despite thrombectomy being an extremely beneficial treatment for severe stroke, many eligible patients remain untreated, largely because of a lack of neurointerventionalists in many regions worldwide. They estimate that about 15% of all stroke patients are eligible for thrombectomy but only around 2% of stroke patients in Europe actually receive such treatment.

Dr. Widimsky, an interventional cardiologist, first thought of the idea of using cardiologists to perform stroke thrombectomies after a good friend and colleague suffered a severe stroke in 2010.

“This made us realize that our hospital needed to be more active in the stroke field,” he said. “We decided that we needed to start doing stroke interventions.”

But the major problem was the lack of neurointerventionalists.

“There are not enough neurointerventionalists in Europe. Interventional cardiologists can perform thousands of procedures every year whereas a neurointerventionalist will at best perform hundreds a year. It is quicker and simpler to train the cardiologist to do it,” Dr. Widimsky said.  

They hired one neurointerventionalist to lead the program. “He was our tutor, he taught us his skills,” Dr. Widimsky said. “The cath lab is open 24/7, but if we only have one neurointerventionalist we cannot offer a 24/7 service for stroke thrombectomy. But if we merge with cardiology then we can,” he added.

Their hospital is a very busy center for myocardial infarction, percutaneous coronary intervention, and carotid stenting, he noted. “It is not difficult to make the step from that to stroke thrombectomy. Interventional cardiologists are used to performing carotid and coronary artery stenting. Stroke thrombectomy is a similar technique. The thrombectomy procedure is different from coronary angioplasty but it is not more difficult.  Actually, I think coronary angioplasty can be more difficult.”  

Dr. Widimsky explained that cardiologists need to learn about the brain anatomy and physiology and learn the stroke imaging techniques. “I spent 1 month in the U.S. learning stroke interventions working with simulators,” he said. “I think interventional cardiologists can learn what they need to know in about 6 months. I would recommend they should watch about 50 procedures and perform at least 25 under supervision.”

He said this model is the way forward and hopes it will become routine. Thrombectomy is “tremendously effective” in improving outcomes in severe strokes, with a number needed to treat (NNT) of just 2.6 to prevent long-term disability in one patient, he said, while other procedures can have NNTs of 50 or more.  

“But millions of patients with acute severe stroke are not getting this life-changing treatment,” he added. “We must do everything we can to make this service available to as many patients as possible.”

Dr. Widimsky acknowledges that there has been opposition to this idea from the neurointerventionalist professional bodies but this has lessened recently, at least in Europe. And a program that allows interventionalists with experience in extracranial carotid and vertebral endovascular procedures to “fast-track” technical training has now been proposed.

“There is an enormous unmet need for stroke thrombectomy in Europe, with some countries needing to increase the number of procedures done by 10 or 20 times. These include the U.K., Sweden, Italy, Spain, and Portugal. This cannot be done without cardiology,” Dr. Widimsky said.  
 

Editorial strongly supportive

An accompanying editorial strongly endorses the idea of using interdisciplinary teams to deliver high standard stroke care.

Marius Hornung, MD, and Horst Sievert, MD, from CardioVascular Center Frankfurt (Germany), point out that many experienced cardiologists are trained in performing carotid artery interventions and are therefore experienced in accessing the supra-aortic arteries.

Ted Bosworth/MDedge News

Opposition in the United States

Dr. Widimsky explained that this proposal may not be so applicable to the United States, where the need for more clinicians capable of performing stroke thrombectomies does not appear to be as critical, possibly because vascular neurosurgeons as well as neuroradiologists are qualified to undertake these procedures.

In an interview, J. Mocco, MD, director of the cerebrovascular center, department of neurological surgery, at Mount Sinai Health System, New York, confirmed that this was the case.

MDedge News

A version of this article first appeared on Medscape.com.

Cardiologists experienced in cardiac interventions can competently perform stroke thrombectomy after a short period of training, with outcomes comparable to those achieved by neuroradiology centers, a new study suggests.
 

“Using interventional cardiologists in this way will help address the huge unmet need for stroke thrombectomy that currently exists,” senior author Petr Widimsky, MD, said in an interview.

Although this may be a feasible way forward in Europe, there is strong opposition to such a proposal from U.S. neurointerventionalists.  

The study, published in the April 12 issue of JACC: Cardiovascular Interventions, describes the establishment of a stroke thrombectomy program in University Hospital Kralovske Vinohrady, a large tertiary hospital in Prague, Czech Republic.

The hospital did not have a neurointerventional program until 2012 when a joint program was started involving an experienced team of cardiologists, angiologists, and one interventional radiologist who trained the cardiologists on the thrombectomy procedure.

The current paper reports on the outcomes of the 333 patients with large vessel occlusion stroke treated under this program between October 2012 and December 2019.

The decision to perform catheter-based thrombectomy was made by a neurologist and was based on acute stroke clinical symptoms and CT angiographic findings.

Results show that functional clinical outcomes, assessed via the Modified Rankin Scale (mRS) score at 3 months, did not vary significantly across years 2012 to 2019, with a favorable outcome (mRS 0 to 2) achieved in 47.9% of patients.

Symptomatic intracerebral hemorrhage occurred in 19 patients (5.7%) and embolization in a new vascular territory occurred in 6 patients (1.8%), outcomes similar to those of neuroradiology centers.

The desired clinical results were achieved from the onset of the program, without any signs of a learning curve effect, they reported.

“These findings support the potential role of interventional cardiac cath labs in the treatment of acute stroke in regions where this therapy is not readily available due to the lack of neurointerventionalists,” the authors concluded.

“Our main message is that our results were excellent from the beginning,” Dr. Widimsky said. “When centers prepare properly, they can achieve excellent results from the beginning with cardiologists who are experienced in interventional procedures and who have spent sufficient time learning about the brain.”  

The authors noted that despite thrombectomy being an extremely beneficial treatment for severe stroke, many eligible patients remain untreated, largely because of a lack of neurointerventionalists in many regions worldwide. They estimate that about 15% of all stroke patients are eligible for thrombectomy but only around 2% of stroke patients in Europe actually receive such treatment.

Dr. Widimsky, an interventional cardiologist, first thought of the idea of using cardiologists to perform stroke thrombectomies after a good friend and colleague suffered a severe stroke in 2010.

“This made us realize that our hospital needed to be more active in the stroke field,” he said. “We decided that we needed to start doing stroke interventions.”

But the major problem was the lack of neurointerventionalists.

“There are not enough neurointerventionalists in Europe. Interventional cardiologists can perform thousands of procedures every year whereas a neurointerventionalist will at best perform hundreds a year. It is quicker and simpler to train the cardiologist to do it,” Dr. Widimsky said.  

They hired one neurointerventionalist to lead the program. “He was our tutor, he taught us his skills,” Dr. Widimsky said. “The cath lab is open 24/7, but if we only have one neurointerventionalist we cannot offer a 24/7 service for stroke thrombectomy. But if we merge with cardiology then we can,” he added.

Their hospital is a very busy center for myocardial infarction, percutaneous coronary intervention, and carotid stenting, he noted. “It is not difficult to make the step from that to stroke thrombectomy. Interventional cardiologists are used to performing carotid and coronary artery stenting. Stroke thrombectomy is a similar technique. The thrombectomy procedure is different from coronary angioplasty but it is not more difficult.  Actually, I think coronary angioplasty can be more difficult.”  

Dr. Widimsky explained that cardiologists need to learn about the brain anatomy and physiology and learn the stroke imaging techniques. “I spent 1 month in the U.S. learning stroke interventions working with simulators,” he said. “I think interventional cardiologists can learn what they need to know in about 6 months. I would recommend they should watch about 50 procedures and perform at least 25 under supervision.”

He said this model is the way forward and hopes it will become routine. Thrombectomy is “tremendously effective” in improving outcomes in severe strokes, with a number needed to treat (NNT) of just 2.6 to prevent long-term disability in one patient, he said, while other procedures can have NNTs of 50 or more.  

“But millions of patients with acute severe stroke are not getting this life-changing treatment,” he added. “We must do everything we can to make this service available to as many patients as possible.”

Dr. Widimsky acknowledges that there has been opposition to this idea from the neurointerventionalist professional bodies but this has lessened recently, at least in Europe. And a program that allows interventionalists with experience in extracranial carotid and vertebral endovascular procedures to “fast-track” technical training has now been proposed.

“There is an enormous unmet need for stroke thrombectomy in Europe, with some countries needing to increase the number of procedures done by 10 or 20 times. These include the U.K., Sweden, Italy, Spain, and Portugal. This cannot be done without cardiology,” Dr. Widimsky said.  
 

Editorial strongly supportive

An accompanying editorial strongly endorses the idea of using interdisciplinary teams to deliver high standard stroke care.

Marius Hornung, MD, and Horst Sievert, MD, from CardioVascular Center Frankfurt (Germany), point out that many experienced cardiologists are trained in performing carotid artery interventions and are therefore experienced in accessing the supra-aortic arteries.

Ted Bosworth/MDedge News

Opposition in the United States

Dr. Widimsky explained that this proposal may not be so applicable to the United States, where the need for more clinicians capable of performing stroke thrombectomies does not appear to be as critical, possibly because vascular neurosurgeons as well as neuroradiologists are qualified to undertake these procedures.

In an interview, J. Mocco, MD, director of the cerebrovascular center, department of neurological surgery, at Mount Sinai Health System, New York, confirmed that this was the case.

MDedge News

A version of this article first appeared on Medscape.com.

New Supplement to Federal Practitioner: Advances in Neurology

Read more about:

• Lumbar Fusion With PEEK Rods Use for Patients With Degenerative Disease
• Systemic Literature Review of the Use of Virtual Reality for Rehabilitation in Parkinson Disease
• COVID-19 Vaccine in Veterans With Multiple Sclerosis: Protect the Vulnerable

Click here to read the supplement or click on the image

New Supplement to Federal Practitioner: Advances in Neurology

Read more about:

• Lumbar Fusion With PEEK Rods Use for Patients With Degenerative Disease
• Systemic Literature Review of the Use of Virtual Reality for Rehabilitation in Parkinson Disease
• COVID-19 Vaccine in Veterans With Multiple Sclerosis: Protect the Vulnerable

Click here to read the supplement or click on the image

New Supplement to Federal Practitioner: Advances in Neurology

Read more about:

• Lumbar Fusion With PEEK Rods Use for Patients With Degenerative Disease
• Systemic Literature Review of the Use of Virtual Reality for Rehabilitation in Parkinson Disease
• COVID-19 Vaccine in Veterans With Multiple Sclerosis: Protect the Vulnerable

Click here to read the supplement or click on the image

An advisory committee to the Centers for Disease Control and Prevention is addressing the safety of the Johnson & Johnson COVID-19 vaccine on April 14, 2021, after the CDC and Food and Drug Administration recommended that states hold off on using it pending a detailed review of six cases of the same kind of rare but serious event – a blood clot in the vessels that drain blood from the brain combined with a large drop in platelets, which increases the risk for bleeding.

This combination can lead to severe strokes that can lead to brain damage or death. Among the six cases reported, which came to light over the past 3 weeks, one person died, according to the CDC. All six were women and ranged in age from 18 to 48 years.

According to a report from the Vaccine Adverse Event Reporting System (VAERS), which is maintained by the Department of Health & Human Services, the woman who died was 45. She developed a gradually worsening headache about a week after receiving the Johnson & Johnson vaccine.

On March 17, the day she came to the hospital, she was dry heaving. Her headache had suddenly gotten much worse, and the left side of her body was weak, which are signs of a stroke. A CT scan revealed both bleeding in her brain and a clot in her cortical vein. She died the following day.

In addition to VAERS, which accepts reports from anyone, the CDC and FDA are monitoring at least eight other safety systems maintained by hospitals, research centers, long-term care facilities, and insurance companies for signs of trouble with the vaccines. VAERS data is searchable and open to the public. Most of these systems are not publicly available to protect patient privacy. It’s unclear which systems detected the six cases cited by federal regulators.

“These are very serious and potentially fatal problems occurring in a healthy young adult. It’s serious and we need to get to the bottom of it,” said Ed Belongia, MD, director of the Center for Clinical Epidemiology and Population Health at the Marshfield (Wis.) Clinic Research Institute. Dr. Belongia leads a research team that helps the CDC monitor vaccine safety and effectiveness. 

“Safety is always the highest priority, and I think what we’ve seen here in the past 24 hours is our vaccine safety monitoring system is working,” he said.

Others agree. “I think what CDC and FDA have detected is a rare, but likely real adverse event associated with this vaccine,” said Paul Offit, MD, director of vaccine education at Children’s Hospital of Philadelphia.

Although much is still unknown about these events, they follow a similar pattern of blood clots reported with the AstraZeneca vaccine in Europe. That vaccine is now sold under the brand name Vaxzevria. 

This has experts questioning whether all vaccines of this type may cause these rare clots.

“I think it’s likely a class effect,” said Dr. Offit, who was a member of the FDA advisory committee that reviewed clinical trial data on the J&J vaccine before it was authorized for use.
 

Adenovirus vaccines scrutinized

Both the Johnson & Johnson and Vaxzevria vaccines use an adenovirus to ferry genetic instructions for making the coronaviruses spike protein into our cells.

Adenoviruses are common, relatively simple viruses that normally cause mild cold or flu symptoms. The ones used in the vaccine are disabled so they can’t make us sick. They’re more like Trojan horses. 

Once inside our cells, they release the DNA instructions they carry to make the spike protein of the new coronavirus. Those cells then crank out copies of the spike protein, which then get displayed on the outer surface of the cell membrane where they are recognized by the immune system. 

The immune system then makes antibodies and other defenses against the spike so that, when the real coronavirus comes along, our bodies are ready to fight the infection.

There’s no question the vaccine works. In clinical trials, the Johnson & Johnson vaccine was 66% percent effective at preventing against moderate to severe COVID-19 infection, and none of the patients who got COVID-19 after vaccination had to be admitted to the hospital or died.

The idea behind using adenoviruses in vaccines isn’t a new one. In a kind of fight-fire-with-fire approach, the idea is to use a virus, which is good at infecting us, to fight a different kind of virus.

Researchers have been working on the concept for about 10 years, but the COVID-19 vaccines that use this technology are some of the first adenovirus-vector vaccines deployed in humans. 

Only one other adenovirus vaccine, for Ebola, has been approved for use in humans. It was approved in Europe last year. Before the Johnson & Johnson vaccine, no other adenovirus vector has been available for use in humans in the United States.

There are six adenovirus-vector vaccines for COVID-19. In addition to AstraZeneca and Johnson & Johnson, there’s the Russian-developed vaccine Sputnik V, along with CanSino from China, and the Covishield vaccine in India.

Adenovirus vaccines are more stable than the mRNA vaccines. That makes them easier to store and transport. 

But they have a significant downside, too. Because adenoviruses infect humans out in the world, we already make antibodies against them. So there’s always a danger that our immune systems might recognize and react to the vaccine, rendering it ineffective. For that reason, scientists try to carefully select the adenovirus vectors, or carriers, they use.

The two vaccines under investigation for blood clots are slightly different. The Johnson & Johnson vaccine uses the vector AD26, because most of the population lacks preexisting immunity to it. Vaxzevria uses an adenovirus that infects chimpanzees, called ChAdOx1. 

Vaxzevria has been widely used in Europe but has not yet been authorized in the United States.

On April 7, the European Medicines Agency, Europe’s counterpart to the FDA, ruled that unusual blood clots with low blood platelets should be listed as rare side effects on the Vaxzevria vaccine.

The decision came after reviewing 62 cases of cerebral venous sinus thrombosis (CVST) linked to the vaccine and 25 cases of another rare type of clot, called a splanchnic vein thrombosis. Splanchnic veins drain blood from the major organs in the digestive system, including the stomach, liver, and intestines; 18 of those events were fatal.

The reports were culled from reporting in Europe and the United Kingdom, where around 25 million people have received the Vaxzevria vaccine, making these clots exceptionally rare, but serious.

So far, six cases of CVST have been reported in the United States, after more than 7 million doses of the Johnson & Johnson vaccines have been administered.

A key question for U.S. regulators will be the background rate for these types of rare combinations of clots and deplenished platelets. The background rate is the number of events that would be expected to occur naturally in a population of unvaccinated people. On a press call on April 13, Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, was asked about the frequency of this dangerous combination. He said the combination of low platelets and clots was so rare that it was hard to pinpoint, but might be somewhere between 2 and 14 cases per million people over the course of a year.

The first Johnson & Johnson doses were given in early March. That means the six cases came to light within the first few weeks of use of the vaccine in the United States, a very short amount of time.

“These were six cases per million people for 2 weeks, which is the same thing as 25 million per year, so it’s clearly above the background rate,” Dr. Offit said.
 

Studies suggest possible mechanism

On April 9, the New England Journal of Medicine published a detailed evaluation of the 11 patients in Germany and Austria who developed the rare clots after their Vaxzevria vaccines.

The study detected rare antibodies to a signaling protein called platelet factor 4, which helps to coordinate clot formation.

These same type of antibodies form in some people given the blood thinning drug heparin. In those reactions, which are also exceptionally rare, the same type of syndrome develops, leading to large, devastating clots that consume circulating platelets.

It’s not yet clear whether people who develop reactions to the vaccines already have some platelet factor 4 antibodies before they are vaccinated, or whether the vaccines somehow spur the body to make these antibodies, which then launch a kind of autoimmune attack.

The researchers on the paper gave the syndrome a name, vaccine-induced thrombotic thrombocytopenia (VITT).

It’s also not clear why more cases seem to be in women than in men. Andrew Eisenberger, MD, an associate professor of hematology and oncology at Columbia University, New York, said the most common causes of cerebral venous sinus thrombosis have to do with conditions that raise estrogen levels, like pregnancy and hormonal contraception.

“Estrogen naturally leads to changes in several clotting proteins in the blood that may predispose to abnormal blood clotting in a few different sites in the body,” he said. “The clotting changes we are encountering with some of COVID-19 vaccines are likely to be synergistic with the effects of estrogen on the blood.”

No matter the cause, the CDC on April 13 alerted doctors to keep a high index of suspicion for VITT in patients who have received the Johnson & Johnson vaccination within the last 2 weeks. In those patients, the usual course of treatment with blood thinning drugs like heparin may be harmful.

Symptoms to watch for include severe headache or backache, new neurologic symptoms, severe abdominal pain, shortness of breath, leg swelling, tiny red spots on the skin, or easy bruising. 
 

Grappling with evidence

The CDC’s Advisory Committee on Immunization Practices will meet today in an emergency session to review the cases and see if any changes are needed to use of the J&J vaccine in the United States.

Last week, for example, the United Kingdom restricted the use of the AstraZeneca vaccine in people aged younger than 30 years, saying the risks and benefits of vaccination are “more finely balanced” for this age group.

With cases of COVID-19 rising again in the United States, and the Johnson & Johnson vaccine currently the most convenient form of protection against the virus, the committee will have to weigh the risks of that infection against the risk of rare clots caused by vaccination.

They will also likely have to rule out whether any of the cases had COVID. At least one study has reported CVST clots in three patients with confirmed COVID infections. In Europe, COVID infection did not seem to play a role in the formation of the clots with low platelets.

Hilda Bastian, PhD, a clinical trials expert who cofounded the Cochrane Collaboration, said it won’t be an easy task. Much will depend on how certain the committee members feel they know about all the events linked to the vaccine.

“That’s the really, really hard issue from my point of view for them right this moment. Have we missed any? Or how many are we likely to have missed?” asked Dr. Bastian, who lives in Australia.

“In a country that size with that fragmented [of] a health care system, how sure can you be that you know them all? That’s going to be a really difficult situation for them to grapple with, the quality of information that they’ve got,” she said.

A version of this article first appeared on Medscape.com.

An advisory committee to the Centers for Disease Control and Prevention is addressing the safety of the Johnson & Johnson COVID-19 vaccine on April 14, 2021, after the CDC and Food and Drug Administration recommended that states hold off on using it pending a detailed review of six cases of the same kind of rare but serious event – a blood clot in the vessels that drain blood from the brain combined with a large drop in platelets, which increases the risk for bleeding.

This combination can lead to severe strokes that can lead to brain damage or death. Among the six cases reported, which came to light over the past 3 weeks, one person died, according to the CDC. All six were women and ranged in age from 18 to 48 years.

According to a report from the Vaccine Adverse Event Reporting System (VAERS), which is maintained by the Department of Health & Human Services, the woman who died was 45. She developed a gradually worsening headache about a week after receiving the Johnson & Johnson vaccine.

On March 17, the day she came to the hospital, she was dry heaving. Her headache had suddenly gotten much worse, and the left side of her body was weak, which are signs of a stroke. A CT scan revealed both bleeding in her brain and a clot in her cortical vein. She died the following day.

In addition to VAERS, which accepts reports from anyone, the CDC and FDA are monitoring at least eight other safety systems maintained by hospitals, research centers, long-term care facilities, and insurance companies for signs of trouble with the vaccines. VAERS data is searchable and open to the public. Most of these systems are not publicly available to protect patient privacy. It’s unclear which systems detected the six cases cited by federal regulators.

“These are very serious and potentially fatal problems occurring in a healthy young adult. It’s serious and we need to get to the bottom of it,” said Ed Belongia, MD, director of the Center for Clinical Epidemiology and Population Health at the Marshfield (Wis.) Clinic Research Institute. Dr. Belongia leads a research team that helps the CDC monitor vaccine safety and effectiveness. 

“Safety is always the highest priority, and I think what we’ve seen here in the past 24 hours is our vaccine safety monitoring system is working,” he said.

Others agree. “I think what CDC and FDA have detected is a rare, but likely real adverse event associated with this vaccine,” said Paul Offit, MD, director of vaccine education at Children’s Hospital of Philadelphia.

Although much is still unknown about these events, they follow a similar pattern of blood clots reported with the AstraZeneca vaccine in Europe. That vaccine is now sold under the brand name Vaxzevria. 

This has experts questioning whether all vaccines of this type may cause these rare clots.

“I think it’s likely a class effect,” said Dr. Offit, who was a member of the FDA advisory committee that reviewed clinical trial data on the J&J vaccine before it was authorized for use.
 

Adenovirus vaccines scrutinized

Both the Johnson & Johnson and Vaxzevria vaccines use an adenovirus to ferry genetic instructions for making the coronaviruses spike protein into our cells.

Adenoviruses are common, relatively simple viruses that normally cause mild cold or flu symptoms. The ones used in the vaccine are disabled so they can’t make us sick. They’re more like Trojan horses. 

Once inside our cells, they release the DNA instructions they carry to make the spike protein of the new coronavirus. Those cells then crank out copies of the spike protein, which then get displayed on the outer surface of the cell membrane where they are recognized by the immune system. 

The immune system then makes antibodies and other defenses against the spike so that, when the real coronavirus comes along, our bodies are ready to fight the infection.

There’s no question the vaccine works. In clinical trials, the Johnson & Johnson vaccine was 66% percent effective at preventing against moderate to severe COVID-19 infection, and none of the patients who got COVID-19 after vaccination had to be admitted to the hospital or died.

The idea behind using adenoviruses in vaccines isn’t a new one. In a kind of fight-fire-with-fire approach, the idea is to use a virus, which is good at infecting us, to fight a different kind of virus.

Researchers have been working on the concept for about 10 years, but the COVID-19 vaccines that use this technology are some of the first adenovirus-vector vaccines deployed in humans. 

Only one other adenovirus vaccine, for Ebola, has been approved for use in humans. It was approved in Europe last year. Before the Johnson & Johnson vaccine, no other adenovirus vector has been available for use in humans in the United States.

There are six adenovirus-vector vaccines for COVID-19. In addition to AstraZeneca and Johnson & Johnson, there’s the Russian-developed vaccine Sputnik V, along with CanSino from China, and the Covishield vaccine in India.

Adenovirus vaccines are more stable than the mRNA vaccines. That makes them easier to store and transport. 

But they have a significant downside, too. Because adenoviruses infect humans out in the world, we already make antibodies against them. So there’s always a danger that our immune systems might recognize and react to the vaccine, rendering it ineffective. For that reason, scientists try to carefully select the adenovirus vectors, or carriers, they use.

The two vaccines under investigation for blood clots are slightly different. The Johnson & Johnson vaccine uses the vector AD26, because most of the population lacks preexisting immunity to it. Vaxzevria uses an adenovirus that infects chimpanzees, called ChAdOx1. 

Vaxzevria has been widely used in Europe but has not yet been authorized in the United States.

On April 7, the European Medicines Agency, Europe’s counterpart to the FDA, ruled that unusual blood clots with low blood platelets should be listed as rare side effects on the Vaxzevria vaccine.

The decision came after reviewing 62 cases of cerebral venous sinus thrombosis (CVST) linked to the vaccine and 25 cases of another rare type of clot, called a splanchnic vein thrombosis. Splanchnic veins drain blood from the major organs in the digestive system, including the stomach, liver, and intestines; 18 of those events were fatal.

The reports were culled from reporting in Europe and the United Kingdom, where around 25 million people have received the Vaxzevria vaccine, making these clots exceptionally rare, but serious.

So far, six cases of CVST have been reported in the United States, after more than 7 million doses of the Johnson & Johnson vaccines have been administered.

A key question for U.S. regulators will be the background rate for these types of rare combinations of clots and deplenished platelets. The background rate is the number of events that would be expected to occur naturally in a population of unvaccinated people. On a press call on April 13, Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, was asked about the frequency of this dangerous combination. He said the combination of low platelets and clots was so rare that it was hard to pinpoint, but might be somewhere between 2 and 14 cases per million people over the course of a year.

The first Johnson & Johnson doses were given in early March. That means the six cases came to light within the first few weeks of use of the vaccine in the United States, a very short amount of time.

“These were six cases per million people for 2 weeks, which is the same thing as 25 million per year, so it’s clearly above the background rate,” Dr. Offit said.
 

Studies suggest possible mechanism

On April 9, the New England Journal of Medicine published a detailed evaluation of the 11 patients in Germany and Austria who developed the rare clots after their Vaxzevria vaccines.

The study detected rare antibodies to a signaling protein called platelet factor 4, which helps to coordinate clot formation.

These same type of antibodies form in some people given the blood thinning drug heparin. In those reactions, which are also exceptionally rare, the same type of syndrome develops, leading to large, devastating clots that consume circulating platelets.

It’s not yet clear whether people who develop reactions to the vaccines already have some platelet factor 4 antibodies before they are vaccinated, or whether the vaccines somehow spur the body to make these antibodies, which then launch a kind of autoimmune attack.

The researchers on the paper gave the syndrome a name, vaccine-induced thrombotic thrombocytopenia (VITT).

It’s also not clear why more cases seem to be in women than in men. Andrew Eisenberger, MD, an associate professor of hematology and oncology at Columbia University, New York, said the most common causes of cerebral venous sinus thrombosis have to do with conditions that raise estrogen levels, like pregnancy and hormonal contraception.

“Estrogen naturally leads to changes in several clotting proteins in the blood that may predispose to abnormal blood clotting in a few different sites in the body,” he said. “The clotting changes we are encountering with some of COVID-19 vaccines are likely to be synergistic with the effects of estrogen on the blood.”

No matter the cause, the CDC on April 13 alerted doctors to keep a high index of suspicion for VITT in patients who have received the Johnson & Johnson vaccination within the last 2 weeks. In those patients, the usual course of treatment with blood thinning drugs like heparin may be harmful.

Symptoms to watch for include severe headache or backache, new neurologic symptoms, severe abdominal pain, shortness of breath, leg swelling, tiny red spots on the skin, or easy bruising. 
 

Grappling with evidence

The CDC’s Advisory Committee on Immunization Practices will meet today in an emergency session to review the cases and see if any changes are needed to use of the J&J vaccine in the United States.

Last week, for example, the United Kingdom restricted the use of the AstraZeneca vaccine in people aged younger than 30 years, saying the risks and benefits of vaccination are “more finely balanced” for this age group.

With cases of COVID-19 rising again in the United States, and the Johnson & Johnson vaccine currently the most convenient form of protection against the virus, the committee will have to weigh the risks of that infection against the risk of rare clots caused by vaccination.

They will also likely have to rule out whether any of the cases had COVID. At least one study has reported CVST clots in three patients with confirmed COVID infections. In Europe, COVID infection did not seem to play a role in the formation of the clots with low platelets.

Hilda Bastian, PhD, a clinical trials expert who cofounded the Cochrane Collaboration, said it won’t be an easy task. Much will depend on how certain the committee members feel they know about all the events linked to the vaccine.

“That’s the really, really hard issue from my point of view for them right this moment. Have we missed any? Or how many are we likely to have missed?” asked Dr. Bastian, who lives in Australia.

“In a country that size with that fragmented [of] a health care system, how sure can you be that you know them all? That’s going to be a really difficult situation for them to grapple with, the quality of information that they’ve got,” she said.

A version of this article first appeared on Medscape.com.

An advisory committee to the Centers for Disease Control and Prevention is addressing the safety of the Johnson & Johnson COVID-19 vaccine on April 14, 2021, after the CDC and Food and Drug Administration recommended that states hold off on using it pending a detailed review of six cases of the same kind of rare but serious event – a blood clot in the vessels that drain blood from the brain combined with a large drop in platelets, which increases the risk for bleeding.

This combination can lead to severe strokes that can lead to brain damage or death. Among the six cases reported, which came to light over the past 3 weeks, one person died, according to the CDC. All six were women and ranged in age from 18 to 48 years.

According to a report from the Vaccine Adverse Event Reporting System (VAERS), which is maintained by the Department of Health & Human Services, the woman who died was 45. She developed a gradually worsening headache about a week after receiving the Johnson & Johnson vaccine.

On March 17, the day she came to the hospital, she was dry heaving. Her headache had suddenly gotten much worse, and the left side of her body was weak, which are signs of a stroke. A CT scan revealed both bleeding in her brain and a clot in her cortical vein. She died the following day.

In addition to VAERS, which accepts reports from anyone, the CDC and FDA are monitoring at least eight other safety systems maintained by hospitals, research centers, long-term care facilities, and insurance companies for signs of trouble with the vaccines. VAERS data is searchable and open to the public. Most of these systems are not publicly available to protect patient privacy. It’s unclear which systems detected the six cases cited by federal regulators.

“These are very serious and potentially fatal problems occurring in a healthy young adult. It’s serious and we need to get to the bottom of it,” said Ed Belongia, MD, director of the Center for Clinical Epidemiology and Population Health at the Marshfield (Wis.) Clinic Research Institute. Dr. Belongia leads a research team that helps the CDC monitor vaccine safety and effectiveness. 

“Safety is always the highest priority, and I think what we’ve seen here in the past 24 hours is our vaccine safety monitoring system is working,” he said.

Others agree. “I think what CDC and FDA have detected is a rare, but likely real adverse event associated with this vaccine,” said Paul Offit, MD, director of vaccine education at Children’s Hospital of Philadelphia.

Although much is still unknown about these events, they follow a similar pattern of blood clots reported with the AstraZeneca vaccine in Europe. That vaccine is now sold under the brand name Vaxzevria. 

This has experts questioning whether all vaccines of this type may cause these rare clots.

“I think it’s likely a class effect,” said Dr. Offit, who was a member of the FDA advisory committee that reviewed clinical trial data on the J&J vaccine before it was authorized for use.
 

Adenovirus vaccines scrutinized

Both the Johnson & Johnson and Vaxzevria vaccines use an adenovirus to ferry genetic instructions for making the coronaviruses spike protein into our cells.

Adenoviruses are common, relatively simple viruses that normally cause mild cold or flu symptoms. The ones used in the vaccine are disabled so they can’t make us sick. They’re more like Trojan horses. 

Once inside our cells, they release the DNA instructions they carry to make the spike protein of the new coronavirus. Those cells then crank out copies of the spike protein, which then get displayed on the outer surface of the cell membrane where they are recognized by the immune system. 

The immune system then makes antibodies and other defenses against the spike so that, when the real coronavirus comes along, our bodies are ready to fight the infection.

There’s no question the vaccine works. In clinical trials, the Johnson & Johnson vaccine was 66% percent effective at preventing against moderate to severe COVID-19 infection, and none of the patients who got COVID-19 after vaccination had to be admitted to the hospital or died.

The idea behind using adenoviruses in vaccines isn’t a new one. In a kind of fight-fire-with-fire approach, the idea is to use a virus, which is good at infecting us, to fight a different kind of virus.

Researchers have been working on the concept for about 10 years, but the COVID-19 vaccines that use this technology are some of the first adenovirus-vector vaccines deployed in humans. 

Only one other adenovirus vaccine, for Ebola, has been approved for use in humans. It was approved in Europe last year. Before the Johnson & Johnson vaccine, no other adenovirus vector has been available for use in humans in the United States.

There are six adenovirus-vector vaccines for COVID-19. In addition to AstraZeneca and Johnson & Johnson, there’s the Russian-developed vaccine Sputnik V, along with CanSino from China, and the Covishield vaccine in India.

Adenovirus vaccines are more stable than the mRNA vaccines. That makes them easier to store and transport. 

But they have a significant downside, too. Because adenoviruses infect humans out in the world, we already make antibodies against them. So there’s always a danger that our immune systems might recognize and react to the vaccine, rendering it ineffective. For that reason, scientists try to carefully select the adenovirus vectors, or carriers, they use.

The two vaccines under investigation for blood clots are slightly different. The Johnson & Johnson vaccine uses the vector AD26, because most of the population lacks preexisting immunity to it. Vaxzevria uses an adenovirus that infects chimpanzees, called ChAdOx1. 

Vaxzevria has been widely used in Europe but has not yet been authorized in the United States.

On April 7, the European Medicines Agency, Europe’s counterpart to the FDA, ruled that unusual blood clots with low blood platelets should be listed as rare side effects on the Vaxzevria vaccine.

The decision came after reviewing 62 cases of cerebral venous sinus thrombosis (CVST) linked to the vaccine and 25 cases of another rare type of clot, called a splanchnic vein thrombosis. Splanchnic veins drain blood from the major organs in the digestive system, including the stomach, liver, and intestines; 18 of those events were fatal.

The reports were culled from reporting in Europe and the United Kingdom, where around 25 million people have received the Vaxzevria vaccine, making these clots exceptionally rare, but serious.

So far, six cases of CVST have been reported in the United States, after more than 7 million doses of the Johnson & Johnson vaccines have been administered.

A key question for U.S. regulators will be the background rate for these types of rare combinations of clots and deplenished platelets. The background rate is the number of events that would be expected to occur naturally in a population of unvaccinated people. On a press call on April 13, Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, was asked about the frequency of this dangerous combination. He said the combination of low platelets and clots was so rare that it was hard to pinpoint, but might be somewhere between 2 and 14 cases per million people over the course of a year.

The first Johnson & Johnson doses were given in early March. That means the six cases came to light within the first few weeks of use of the vaccine in the United States, a very short amount of time.

“These were six cases per million people for 2 weeks, which is the same thing as 25 million per year, so it’s clearly above the background rate,” Dr. Offit said.
 

Studies suggest possible mechanism

On April 9, the New England Journal of Medicine published a detailed evaluation of the 11 patients in Germany and Austria who developed the rare clots after their Vaxzevria vaccines.

The study detected rare antibodies to a signaling protein called platelet factor 4, which helps to coordinate clot formation.

These same type of antibodies form in some people given the blood thinning drug heparin. In those reactions, which are also exceptionally rare, the same type of syndrome develops, leading to large, devastating clots that consume circulating platelets.

It’s not yet clear whether people who develop reactions to the vaccines already have some platelet factor 4 antibodies before they are vaccinated, or whether the vaccines somehow spur the body to make these antibodies, which then launch a kind of autoimmune attack.

The researchers on the paper gave the syndrome a name, vaccine-induced thrombotic thrombocytopenia (VITT).

It’s also not clear why more cases seem to be in women than in men. Andrew Eisenberger, MD, an associate professor of hematology and oncology at Columbia University, New York, said the most common causes of cerebral venous sinus thrombosis have to do with conditions that raise estrogen levels, like pregnancy and hormonal contraception.

“Estrogen naturally leads to changes in several clotting proteins in the blood that may predispose to abnormal blood clotting in a few different sites in the body,” he said. “The clotting changes we are encountering with some of COVID-19 vaccines are likely to be synergistic with the effects of estrogen on the blood.”

No matter the cause, the CDC on April 13 alerted doctors to keep a high index of suspicion for VITT in patients who have received the Johnson & Johnson vaccination within the last 2 weeks. In those patients, the usual course of treatment with blood thinning drugs like heparin may be harmful.

Symptoms to watch for include severe headache or backache, new neurologic symptoms, severe abdominal pain, shortness of breath, leg swelling, tiny red spots on the skin, or easy bruising. 
 

Grappling with evidence

The CDC’s Advisory Committee on Immunization Practices will meet today in an emergency session to review the cases and see if any changes are needed to use of the J&J vaccine in the United States.

Last week, for example, the United Kingdom restricted the use of the AstraZeneca vaccine in people aged younger than 30 years, saying the risks and benefits of vaccination are “more finely balanced” for this age group.

With cases of COVID-19 rising again in the United States, and the Johnson & Johnson vaccine currently the most convenient form of protection against the virus, the committee will have to weigh the risks of that infection against the risk of rare clots caused by vaccination.

They will also likely have to rule out whether any of the cases had COVID. At least one study has reported CVST clots in three patients with confirmed COVID infections. In Europe, COVID infection did not seem to play a role in the formation of the clots with low platelets.

Hilda Bastian, PhD, a clinical trials expert who cofounded the Cochrane Collaboration, said it won’t be an easy task. Much will depend on how certain the committee members feel they know about all the events linked to the vaccine.

“That’s the really, really hard issue from my point of view for them right this moment. Have we missed any? Or how many are we likely to have missed?” asked Dr. Bastian, who lives in Australia.

“In a country that size with that fragmented [of] a health care system, how sure can you be that you know them all? That’s going to be a really difficult situation for them to grapple with, the quality of information that they’ve got,” she said.

A version of this article first appeared on Medscape.com.

Dr. Crain’s excellent review, “Breaking the cycle of medication overuse headache” (J Fam Pract. 2021;70:20-28) provides an approach to the diagnosis and treatment of this common disorder that is consistent with most expert opinion and published guidelines. However, like most articles on this subject, it is missing a critical review of the evidence that supports the existence of this condition and the recommended treatments. 

The strong association between intractable headaches and quantity of medication used makes the diagnosis of medication overuse headache (MOH) attractive with plausible (if unproven) pathophysiological mechanisms. However, reversing the direction of causation (intractable headaches lead to more medication) seems just as likely. While MOH is taken as an article of faith by most headache experts, high-quality studies in support of this theory have not yet been performed.¹

On the other hand, fear of MOH often leads to rigid, arbitrary limitations of abortive medications, blaming of the patient for their symptoms, and the substitution of a host of pharmacologic and nonpharmacologic interventions that similarly lack evidence of efficacy. Patients with chronic migraine are told to take abortive medications early in the headache but not to take them more than twice per week. They hoard their medications while trying to decide if each daily headache is the “big one” that merits depleting their limited supply of medication.

Avoiding medication “overuse” and prescribing from our growing armamentarium of effective preventive medications remain important strategies. However, until we have better evidence, we need to be a little more flexible in prescribing abortive medications and avoid accepting the MOH paradigm as gospel.

David A. Silverstein, MD
Buffalo, NY

Dr. Crain’s excellent review, “Breaking the cycle of medication overuse headache” (J Fam Pract. 2021;70:20-28) provides an approach to the diagnosis and treatment of this common disorder that is consistent with most expert opinion and published guidelines. However, like most articles on this subject, it is missing a critical review of the evidence that supports the existence of this condition and the recommended treatments. 

The strong association between intractable headaches and quantity of medication used makes the diagnosis of medication overuse headache (MOH) attractive with plausible (if unproven) pathophysiological mechanisms. However, reversing the direction of causation (intractable headaches lead to more medication) seems just as likely. While MOH is taken as an article of faith by most headache experts, high-quality studies in support of this theory have not yet been performed.¹

On the other hand, fear of MOH often leads to rigid, arbitrary limitations of abortive medications, blaming of the patient for their symptoms, and the substitution of a host of pharmacologic and nonpharmacologic interventions that similarly lack evidence of efficacy. Patients with chronic migraine are told to take abortive medications early in the headache but not to take them more than twice per week. They hoard their medications while trying to decide if each daily headache is the “big one” that merits depleting their limited supply of medication.

Avoiding medication “overuse” and prescribing from our growing armamentarium of effective preventive medications remain important strategies. However, until we have better evidence, we need to be a little more flexible in prescribing abortive medications and avoid accepting the MOH paradigm as gospel.

David A. Silverstein, MD
Buffalo, NY

Dr. Crain’s excellent review, “Breaking the cycle of medication overuse headache” (J Fam Pract. 2021;70:20-28) provides an approach to the diagnosis and treatment of this common disorder that is consistent with most expert opinion and published guidelines. However, like most articles on this subject, it is missing a critical review of the evidence that supports the existence of this condition and the recommended treatments. 

The strong association between intractable headaches and quantity of medication used makes the diagnosis of medication overuse headache (MOH) attractive with plausible (if unproven) pathophysiological mechanisms. However, reversing the direction of causation (intractable headaches lead to more medication) seems just as likely. While MOH is taken as an article of faith by most headache experts, high-quality studies in support of this theory have not yet been performed.¹

On the other hand, fear of MOH often leads to rigid, arbitrary limitations of abortive medications, blaming of the patient for their symptoms, and the substitution of a host of pharmacologic and nonpharmacologic interventions that similarly lack evidence of efficacy. Patients with chronic migraine are told to take abortive medications early in the headache but not to take them more than twice per week. They hoard their medications while trying to decide if each daily headache is the “big one” that merits depleting their limited supply of medication.

Avoiding medication “overuse” and prescribing from our growing armamentarium of effective preventive medications remain important strategies. However, until we have better evidence, we need to be a little more flexible in prescribing abortive medications and avoid accepting the MOH paradigm as gospel.

David A. Silverstein, MD
Buffalo, NY

THE CASE

A 23-year-old woman with past medical history of bipolar II disorder and a REM-specific seizure disorder that resolved at age 9 presented after a syncopal episode. The patient reported an initial sensation of lightheadedness while at work, which was followed by a syncopal episode with brief (1-2 min) loss of consciousness and a minor head injury.

She denied other prodromal symptoms including chest pain, shortness of breath, ­palpitations, and nausea. She also did not experience convulsions, urinary/bowel incontinence, or confusion upon regaining consciousness.

She denied previous syncopal episodes. However, she reported that, 2 weeks prior, there had been an event similar to that of her presenting complaint. During that episode, she experienced lightheadedness and a fall without loss of consciousness.

The patient had been prescribed a regimen of sertraline 100 mg/d and aripiprazole 10 mg/d to maintain mood stability. She had self-discontinued these medications about 8 months prior to presentation. A recent return of her depressive features had prompted a restart of this regimen 1 week before her first fall, without an initial taper upward.

While in the emergency department, she became bradycardic (heart rate, 38 beats/min) and hypotensive (blood pressure, 70/40 mm Hg). She subsequently became increasingly somnolent and had 1 episode of emesis. An electrocardiogram (EKG) revealed sinus bradycardia without other acute abnormalities (FIGURE).

Blood work including a basic metabolic panel, complete blood count, and cardiac enzymes were all within normal limits. Computed tomography of the head revealed no intracranial pathology. Her vitals were initially unresponsive to a fluid bolus but improved and stabilized after administration of intravenous atropine 0.5 mg.

Aripiprazole was held and sertraline was decreased to 75 mg on hospital Day 1, with close monitoring of her mood. Cardiology was consulted and followed the patient ­during her stay. The patient was monitored on telemetry for 3 days, exhibiting only sinus ­bradycardia with a stable heart rate of 45-55 beats/min. Systolic blood pressures were ­stable within 120 to 130 mm Hg. Transthoracic echocardiogram performed on hospital Day 2 was unremarkable, revealing a normal left ventricular ejection fraction of 65% and no wall motion abnormalities. She had no recurrence of the syncope or emesis.

Continue to: THE DIAGNOSIS

Given her benign cardiac work-up and symptom onset coinciding with the abrupt resumption of high doses of aripiprazole after an 8-month abstinence, the patient’s presentation was attributed to a rather uncommon adverse drug reaction to aripiprazole. This has only been described in a few case reports.

DISCUSSION

Aripiprazole (Abilify) is an atypical antipsychotic frequently used in the treatment of psychiatric conditions, including bipolar disorder and schizophrenia. While the specific therapeutic mechanism is unknown, it is believed that drug efficacy is related to partial agonism at dopamine D₂, serotonin 5-HT_1A, and serotonin 5-HT_2A.¹ As aripiprazole works on a variety of receptors involved in other physiologic processes, clinical adverse effects have been reported, most of which are associated with the adrenergic alpha₁ receptors.¹ These include cognitive impairment and seizures. Cardiovascular adverse effects of aripiprazole include orthostatic hypotension, cardiac arrhythmia, prolonged QT interval, and syncope.^1-5

Family physicians should inquire about aripiprazole use in patients who present with cardiac symptoms.

Selective serotonin reuptake inhibitors (SSRIs) such as sertraline (Zoloft) have also been shown to cause cardiac arrhythmia and syncope.⁶ Although sertraline may have contributed to the patient’s cardiac symptoms, it is more likely that the aripiprazole was the direct cause, as she remained asymptomatic while on a therapeutic dose of sertraline. Furthermore, aripiprazole is primarily metabolized though hepatic CYP2D6, which sertraline has been shown to inhibit.^1,7 Therefore, the concomitant use of sertraline with no initial taper of either medication likely led to an increased effective dose of aripiprazole in our patient and subsequently to her presentation.

Few prior cases have identified aripiprazole as a cause of antipsychotic-associated bradycardic response.⁸ Based on the Adverse Drug Reaction Probability Scale, often referred to as the Naranjo Scale, we believe this to be a probable adverse response in our patient.⁹ Bradycardia followed a reasonable temporal sequence after aripiprazole use with a response previously described in the literature. Symptoms also improved after discontinuation of the drug and other etiologies of the bradycardia were ruled out.

Our patient was discharged with a 30-day cardiac event monitor and a scheduled appointment with Cardiology.

Continue to: THE TAKEAWAY

As this case suggests, there may be an association between aripiprazole and symptomatic bradycardia. Therefore, family physicians should inquire about aripiprazole use in patients who present with cardiac symptoms and consider tapering this medication if other causes cannot be identified. Additionally, given the potential cardiac adverse effects of atypical antipsychotics, physicians may consider ordering baseline and follow-up EKGs to monitor for arrhythmias in patients prescribed aripiprazole. This may be especially prudent when an atypical antipsychotic is combined with an SSRI, as potential cardiac adverse effects may occur more frequently.

CORRESPONDENCE
Kyle Fletke, MD, Department of Family and Community Medicine, University of Maryland School of Medicine, 29 South Paca Street, Baltimore, MD 21201; [email protected]

THE CASE

A 23-year-old woman with past medical history of bipolar II disorder and a REM-specific seizure disorder that resolved at age 9 presented after a syncopal episode. The patient reported an initial sensation of lightheadedness while at work, which was followed by a syncopal episode with brief (1-2 min) loss of consciousness and a minor head injury.

She denied other prodromal symptoms including chest pain, shortness of breath, ­palpitations, and nausea. She also did not experience convulsions, urinary/bowel incontinence, or confusion upon regaining consciousness.

She denied previous syncopal episodes. However, she reported that, 2 weeks prior, there had been an event similar to that of her presenting complaint. During that episode, she experienced lightheadedness and a fall without loss of consciousness.

The patient had been prescribed a regimen of sertraline 100 mg/d and aripiprazole 10 mg/d to maintain mood stability. She had self-discontinued these medications about 8 months prior to presentation. A recent return of her depressive features had prompted a restart of this regimen 1 week before her first fall, without an initial taper upward.

While in the emergency department, she became bradycardic (heart rate, 38 beats/min) and hypotensive (blood pressure, 70/40 mm Hg). She subsequently became increasingly somnolent and had 1 episode of emesis. An electrocardiogram (EKG) revealed sinus bradycardia without other acute abnormalities (FIGURE).

Blood work including a basic metabolic panel, complete blood count, and cardiac enzymes were all within normal limits. Computed tomography of the head revealed no intracranial pathology. Her vitals were initially unresponsive to a fluid bolus but improved and stabilized after administration of intravenous atropine 0.5 mg.

Aripiprazole was held and sertraline was decreased to 75 mg on hospital Day 1, with close monitoring of her mood. Cardiology was consulted and followed the patient ­during her stay. The patient was monitored on telemetry for 3 days, exhibiting only sinus ­bradycardia with a stable heart rate of 45-55 beats/min. Systolic blood pressures were ­stable within 120 to 130 mm Hg. Transthoracic echocardiogram performed on hospital Day 2 was unremarkable, revealing a normal left ventricular ejection fraction of 65% and no wall motion abnormalities. She had no recurrence of the syncope or emesis.

Continue to: THE DIAGNOSIS

Given her benign cardiac work-up and symptom onset coinciding with the abrupt resumption of high doses of aripiprazole after an 8-month abstinence, the patient’s presentation was attributed to a rather uncommon adverse drug reaction to aripiprazole. This has only been described in a few case reports.

DISCUSSION

Aripiprazole (Abilify) is an atypical antipsychotic frequently used in the treatment of psychiatric conditions, including bipolar disorder and schizophrenia. While the specific therapeutic mechanism is unknown, it is believed that drug efficacy is related to partial agonism at dopamine D₂, serotonin 5-HT_1A, and serotonin 5-HT_2A.¹ As aripiprazole works on a variety of receptors involved in other physiologic processes, clinical adverse effects have been reported, most of which are associated with the adrenergic alpha₁ receptors.¹ These include cognitive impairment and seizures. Cardiovascular adverse effects of aripiprazole include orthostatic hypotension, cardiac arrhythmia, prolonged QT interval, and syncope.^1-5

Family physicians should inquire about aripiprazole use in patients who present with cardiac symptoms.

Selective serotonin reuptake inhibitors (SSRIs) such as sertraline (Zoloft) have also been shown to cause cardiac arrhythmia and syncope.⁶ Although sertraline may have contributed to the patient’s cardiac symptoms, it is more likely that the aripiprazole was the direct cause, as she remained asymptomatic while on a therapeutic dose of sertraline. Furthermore, aripiprazole is primarily metabolized though hepatic CYP2D6, which sertraline has been shown to inhibit.^1,7 Therefore, the concomitant use of sertraline with no initial taper of either medication likely led to an increased effective dose of aripiprazole in our patient and subsequently to her presentation.

Few prior cases have identified aripiprazole as a cause of antipsychotic-associated bradycardic response.⁸ Based on the Adverse Drug Reaction Probability Scale, often referred to as the Naranjo Scale, we believe this to be a probable adverse response in our patient.⁹ Bradycardia followed a reasonable temporal sequence after aripiprazole use with a response previously described in the literature. Symptoms also improved after discontinuation of the drug and other etiologies of the bradycardia were ruled out.

Our patient was discharged with a 30-day cardiac event monitor and a scheduled appointment with Cardiology.

Continue to: THE TAKEAWAY

As this case suggests, there may be an association between aripiprazole and symptomatic bradycardia. Therefore, family physicians should inquire about aripiprazole use in patients who present with cardiac symptoms and consider tapering this medication if other causes cannot be identified. Additionally, given the potential cardiac adverse effects of atypical antipsychotics, physicians may consider ordering baseline and follow-up EKGs to monitor for arrhythmias in patients prescribed aripiprazole. This may be especially prudent when an atypical antipsychotic is combined with an SSRI, as potential cardiac adverse effects may occur more frequently.

CORRESPONDENCE
Kyle Fletke, MD, Department of Family and Community Medicine, University of Maryland School of Medicine, 29 South Paca Street, Baltimore, MD 21201; [email protected]

THE CASE

A 23-year-old woman with past medical history of bipolar II disorder and a REM-specific seizure disorder that resolved at age 9 presented after a syncopal episode. The patient reported an initial sensation of lightheadedness while at work, which was followed by a syncopal episode with brief (1-2 min) loss of consciousness and a minor head injury.

She denied other prodromal symptoms including chest pain, shortness of breath, ­palpitations, and nausea. She also did not experience convulsions, urinary/bowel incontinence, or confusion upon regaining consciousness.

She denied previous syncopal episodes. However, she reported that, 2 weeks prior, there had been an event similar to that of her presenting complaint. During that episode, she experienced lightheadedness and a fall without loss of consciousness.

The patient had been prescribed a regimen of sertraline 100 mg/d and aripiprazole 10 mg/d to maintain mood stability. She had self-discontinued these medications about 8 months prior to presentation. A recent return of her depressive features had prompted a restart of this regimen 1 week before her first fall, without an initial taper upward.

While in the emergency department, she became bradycardic (heart rate, 38 beats/min) and hypotensive (blood pressure, 70/40 mm Hg). She subsequently became increasingly somnolent and had 1 episode of emesis. An electrocardiogram (EKG) revealed sinus bradycardia without other acute abnormalities (FIGURE).

Blood work including a basic metabolic panel, complete blood count, and cardiac enzymes were all within normal limits. Computed tomography of the head revealed no intracranial pathology. Her vitals were initially unresponsive to a fluid bolus but improved and stabilized after administration of intravenous atropine 0.5 mg.

Aripiprazole was held and sertraline was decreased to 75 mg on hospital Day 1, with close monitoring of her mood. Cardiology was consulted and followed the patient ­during her stay. The patient was monitored on telemetry for 3 days, exhibiting only sinus ­bradycardia with a stable heart rate of 45-55 beats/min. Systolic blood pressures were ­stable within 120 to 130 mm Hg. Transthoracic echocardiogram performed on hospital Day 2 was unremarkable, revealing a normal left ventricular ejection fraction of 65% and no wall motion abnormalities. She had no recurrence of the syncope or emesis.

Continue to: THE DIAGNOSIS

Given her benign cardiac work-up and symptom onset coinciding with the abrupt resumption of high doses of aripiprazole after an 8-month abstinence, the patient’s presentation was attributed to a rather uncommon adverse drug reaction to aripiprazole. This has only been described in a few case reports.

DISCUSSION

Aripiprazole (Abilify) is an atypical antipsychotic frequently used in the treatment of psychiatric conditions, including bipolar disorder and schizophrenia. While the specific therapeutic mechanism is unknown, it is believed that drug efficacy is related to partial agonism at dopamine D₂, serotonin 5-HT_1A, and serotonin 5-HT_2A.¹ As aripiprazole works on a variety of receptors involved in other physiologic processes, clinical adverse effects have been reported, most of which are associated with the adrenergic alpha₁ receptors.¹ These include cognitive impairment and seizures. Cardiovascular adverse effects of aripiprazole include orthostatic hypotension, cardiac arrhythmia, prolonged QT interval, and syncope.^1-5

Family physicians should inquire about aripiprazole use in patients who present with cardiac symptoms.

Selective serotonin reuptake inhibitors (SSRIs) such as sertraline (Zoloft) have also been shown to cause cardiac arrhythmia and syncope.⁶ Although sertraline may have contributed to the patient’s cardiac symptoms, it is more likely that the aripiprazole was the direct cause, as she remained asymptomatic while on a therapeutic dose of sertraline. Furthermore, aripiprazole is primarily metabolized though hepatic CYP2D6, which sertraline has been shown to inhibit.^1,7 Therefore, the concomitant use of sertraline with no initial taper of either medication likely led to an increased effective dose of aripiprazole in our patient and subsequently to her presentation.

Few prior cases have identified aripiprazole as a cause of antipsychotic-associated bradycardic response.⁸ Based on the Adverse Drug Reaction Probability Scale, often referred to as the Naranjo Scale, we believe this to be a probable adverse response in our patient.⁹ Bradycardia followed a reasonable temporal sequence after aripiprazole use with a response previously described in the literature. Symptoms also improved after discontinuation of the drug and other etiologies of the bradycardia were ruled out.

Our patient was discharged with a 30-day cardiac event monitor and a scheduled appointment with Cardiology.

Continue to: THE TAKEAWAY

As this case suggests, there may be an association between aripiprazole and symptomatic bradycardia. Therefore, family physicians should inquire about aripiprazole use in patients who present with cardiac symptoms and consider tapering this medication if other causes cannot be identified. Additionally, given the potential cardiac adverse effects of atypical antipsychotics, physicians may consider ordering baseline and follow-up EKGs to monitor for arrhythmias in patients prescribed aripiprazole. This may be especially prudent when an atypical antipsychotic is combined with an SSRI, as potential cardiac adverse effects may occur more frequently.

CORRESPONDENCE
Kyle Fletke, MD, Department of Family and Community Medicine, University of Maryland School of Medicine, 29 South Paca Street, Baltimore, MD 21201; [email protected]

Parkinson disease (PD) is the second most common neurodegenerative disorder after Alzheimer disease.¹ Age-standardized incidence rates of PD in population-based studies in Europe and the United States range from 8.6 to 19.0 per 100,000 individuals, using a strict diagnostic criterion for PD.² The negative impact of PD on health-related quality of life imposes a heavy burden on veterans. According to the US Department of Veterans Affairs (VA) National Parkinson’s Disease Consortium, the VA has as many as 50,000 patients with PD under its care. Because of this demand, the VA has strived to revolutionize available services for veterans with PD and related movement disorders.³

The classic motor symptoms of resting tremors, bradykinesia, postural instability, and rigidity of this progressive neurodegenerative disorder is a significant cause of functional limitations that lead to increased falls and inability to perform activities of daily living that challenges the individual and caregiver. ⁴ Rehabilitation has been considered as an adjuvant to surgical and medical treatments for PD to maximize function and minimize complications. High-intensity multimodal exercise boot camps and therapy that focuses on intensely exercising high-amplitude movements, have been shown to improve motor performance in PD.^5,6 Available evidence has shown that exercise-dependent plasticity is the main mechanism underlying the effects of physiotherapy because it increases synaptic strength and affects neurotransmission.⁷ Although there is no consensus on the optimal approach for rehabilitation, innovative techniques have been proposed and studied. One such approach involves virtual reality (VR), which has begun to attract attention for its potential use during rehabilitation.⁸

VR is a simulated experience created by computer-based technology that grants users access to a virtual environment. There are 2 categories of VR: immersive and nonimmersive. Immersive VR is the most direct experience of virtual environments and usually is implemented through a head-mounted display. These displays have monitors in front of each eye, which can provide monocular or biocular imaging with the most common display being small liquid crystal display (LCD) panels.

Nonimmersive VR typically allows a participant to view a virtual environment by using standard high-resolution monitors rather than a headset or an immersive screen room. Many systems are readily available to the general public as electronic interactive entertainment (ie, video games). Interaction with the virtual world happens through interfaces such as keyboards and controllers while viewing a television or computer monitor. These systems often are more accessible and affordable when compared with immersive VR, although this is changing rapidly.

VR therapy is a noninvasive therapeutic alternative modality for PD. This review aims to study the use of VR to treat PD from a rehabilitative standpoint. Although not the only review on the topic, this systematic review is the first to examine the differences between immersive and nonimmersive VR rehabilitation for PD. VR technology is evolving rapidly and the research behind its clinical applications is steadily growing, especially as accessibility improves. This review also is an updated summary of the current literature on the effectiveness of VR therapy during PD rehabilitation.

Methods

Starting in July 2019, the authors searched several databases (PubMed, Google Scholar, Cochrane, and the Physiotherapy Evidence Database [PEDro]) for articles by using the keyword “Parkinson’s disease” combined with either “virtual reality” or “video games.” To find studies specific to rehabilitation, searches included the additional keyword: “rehabilitation.” After compiling an initial set of 89 articles, titles were reviewed to eliminate duplicates. The authors then read the abstracts to exclude study protocols, systematic reviews, and studies that used VR but did not focus on PD or any therapeutic outcome.

Articles were sorted into immersive or nonimmersive virtual reality categories. To be included as immersive VR, studies had to use any type of VR headset or full-scale VR room. Anything less immersive or similar to a traditional video game was included in the nonimmersive VR category. Articles that met inclusion criteria were selected for the systematic review. Criteria for inclusion in this review were: (1) English language; (2) included a study population focused on PD; (3) used some form of VR therapy; and (4) assessed potential rehabilitation by quantitative outcome measures. Only articles published in peer-reviewed journals were included.

Data were extracted into 2 tables specifically modified for this review: immersive and nonimmersive VR. Extracted data included study author name and publication date, study design, methodologic quality, sample size and group allocation, symptom progression via the Hoehn and Yahr Scale (1 to 5), VR modality, presence of control groups, primary outcomes, and primary findings.

Results

This review is reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA).¹⁰ After screening and assessment, 28 articles met inclusion criteria for this review: 7 using immersive VR and 21 using nonimmersive VR (Figure). The immersive studies included 2 RCTs (both with PEDro scores of 5), 1 controlled study with a PEDro score of 5, 1 pre-post pilot study, and 3 cohort studies (Table 2). The nonimmersive studies included 13 RCTs with an average PEDro score of 5.8; 2 pre-post pilot studies, 1 repeated measures study with a historic control, 1 non-RCT, 2 pre-post prospective studies, and 2 cohort studies (1 retrospective and 1 prospective) (Table 3).

Several outcome and assessment tools were used; the most common measures were related to gait, balance, kinematics, and VR feasibility. Studies varied in VR modalities and protocol, ranging from 21 sessions of Nintendo Wii Fit gaming for 7 weeks to 1 session of VR headset use.

Immersive VR

There were fewer immersive VR studies and these studies had lower mean PEDro scores when compared with nonimmersive VR studies. The VR modalities in the immersive studies used a VR headset or a multisensory immersive system that included polarized glasses. All the studies showed positive improvement in primary outcomes with the exception of Ma and colleagues,which showed no difference in success rates or kinematics with moving balls, and only showed improvement in reaching for stationary balls.¹¹ The mean number of participants in the studies was 18.4.

All 7 studies had each participant complete tasks without VR then with the VR therapy. None of the studies compared immersive VR therapy with more conventional therapies. Robles-Garcia and colleagues compared 2 VR groups where the experimental group imitated an avatar’s finger tapping in the VR system while the control group lacked this imitation.¹² The authors found that adding that imitation to the VR group lead to an increase in movement amplitude.

Among the immersive VR studies, only Janeh and colleagues commented on possible adverse effects (AEs) and found that VR was a safe method without AEs of discomfort or simulator sickness.¹³ The other 6 studies did not make any mention or discussion of AEs related to the training.

Nonimmersive VR

VR modalities used in nonimmersive studies included consumer video gaming systems. Nintendo Wii and Microsoft Xbox Kinect were most commonly used. Among the 21 studies, 14 compared VR therapy with a type of traditional exercise (eg, treadmill training, stretching exercises, balance training). The mean number of participants of the studies was 28.3.

Five studies showed a difference between the VR and traditional training groups.^14-18 However, 9 studies showed positive improvement in both groups and found no between-group differences.^19-25 Among the remaining 7 studies, all showed improvement in primary outcomes after adding VR interventional therapy. In 1 RCT, 3 groups were compared (no intervention, Nintendo Wii, and Xbox Kinect) for gait tests, anxiety levels, memory, and attention.²⁶ The authors found that only the Nintendo Wii group showed improvement in outcomes. A prospective cohort study was the only one to compare different doses of VR therapy (10 sessions vs 15 sessions of Nintendo Wii Fit).²⁷ The authors found that both groups demonstrated the same amount of improvement on balance performances with no group effect.

Ten studiesreported no AEs during the training, but also did not define what was considered an AE.^{15,16,19,22-25,27-29} Eight studies did not make any mention of AEs.^{14,17,21,26,27,30-32} Yen and colleagues reported no AEs during training except for the patients’ tendency to fall.²⁰ However, therapists supervised the patients to avoid falls and no falls occurred. Nuic and colleaguesreported 3 serious AEs, unrelated to the training: severe pneumonia (n = 1) and deep-brain stimulation generator replacement (n = 2).³³ During the video game training sessions no specific AEs occurred. Only Pompeu and colleagues defined an AE as any untoward medical occurrence such as convulsion, syncope, dizziness, vertigo, falls, or any medical condition that required hospitalization or disability.³⁴ One researcher registered the occurrence of any AE; however, none occurred during the study period.

Discussion

This systematic review demonstrates that VR therapy is a promising addition to rehabilitation for PD. Evidence supporting VR therapy is limited, but is continually expanding, and current evidence has shown improvement in assessments and rehabilitative outcomes involving PD. Most nonimmersive studies have shown that VR therapy does not lead to better outcomes when compared with traditional therapy but also is not harmful and does provide similar improvement. Immersive VR studies, on the other hand, have not compared therapy with conventional training extensively, and tend to focus more on time for task completion or movement.

There were fewer immersive VR studies than nonimmersive VR studies. This could be because of the increased technological difficulty and demand to correctly execute immersive VR modalities, as well as the—until recently—substantial expense. This might be another reason why the mean PEDro scores for immersive VR RCTs were lower than the mean scores found in nonimmersive RCTs.

Limitations

This review was limited by several factors related to the included studies. A variety of rating scales were used in the immersive and nonimmersive VR studies. Although there was some general overlap with common measurements such as gait, balance, kinematics, and VR feasibility, no studies had the same primary and secondary outcomes. Such heterogeneity in protocols and outcomes limited our ability to draw conclusions from these differing studies. Additionally, the average number of participants of both immersive and nonimmersive studies were small and the statistical significance of findings should be interpreted with caution. Finally, VR devices and systems differed between studies, further limiting comparisons. Although these factors limit this systematic review, we can still identify treatment and research implications. Adequately powered future studies with standardized protocols would further improve the available evidence and support for VR as an intervention.

Conclusions

VR therapy is a promising rehabilitation modality for PD. Additional investigations of VR therapy and PD should include direct comparisons between immersive and nonimmersive VR therapies. It could be hypothesized that the greater immersion and engagement potential of immersive VR would demonstrate greater functional improvement compared with nonimmersive VR, but there is no data to support this for PD. VR therapy for PD appears to be a relatively safe alternative or adjunct to traditional therapy with a potentially positive impact on a variety of symptoms and is growing as an innovative therapeutic approach for PD patients.

Parkinson disease (PD) is the second most common neurodegenerative disorder after Alzheimer disease.¹ Age-standardized incidence rates of PD in population-based studies in Europe and the United States range from 8.6 to 19.0 per 100,000 individuals, using a strict diagnostic criterion for PD.² The negative impact of PD on health-related quality of life imposes a heavy burden on veterans. According to the US Department of Veterans Affairs (VA) National Parkinson’s Disease Consortium, the VA has as many as 50,000 patients with PD under its care. Because of this demand, the VA has strived to revolutionize available services for veterans with PD and related movement disorders.³

The classic motor symptoms of resting tremors, bradykinesia, postural instability, and rigidity of this progressive neurodegenerative disorder is a significant cause of functional limitations that lead to increased falls and inability to perform activities of daily living that challenges the individual and caregiver. ⁴ Rehabilitation has been considered as an adjuvant to surgical and medical treatments for PD to maximize function and minimize complications. High-intensity multimodal exercise boot camps and therapy that focuses on intensely exercising high-amplitude movements, have been shown to improve motor performance in PD.^5,6 Available evidence has shown that exercise-dependent plasticity is the main mechanism underlying the effects of physiotherapy because it increases synaptic strength and affects neurotransmission.⁷ Although there is no consensus on the optimal approach for rehabilitation, innovative techniques have been proposed and studied. One such approach involves virtual reality (VR), which has begun to attract attention for its potential use during rehabilitation.⁸

VR is a simulated experience created by computer-based technology that grants users access to a virtual environment. There are 2 categories of VR: immersive and nonimmersive. Immersive VR is the most direct experience of virtual environments and usually is implemented through a head-mounted display. These displays have monitors in front of each eye, which can provide monocular or biocular imaging with the most common display being small liquid crystal display (LCD) panels.

Nonimmersive VR typically allows a participant to view a virtual environment by using standard high-resolution monitors rather than a headset or an immersive screen room. Many systems are readily available to the general public as electronic interactive entertainment (ie, video games). Interaction with the virtual world happens through interfaces such as keyboards and controllers while viewing a television or computer monitor. These systems often are more accessible and affordable when compared with immersive VR, although this is changing rapidly.

VR therapy is a noninvasive therapeutic alternative modality for PD. This review aims to study the use of VR to treat PD from a rehabilitative standpoint. Although not the only review on the topic, this systematic review is the first to examine the differences between immersive and nonimmersive VR rehabilitation for PD. VR technology is evolving rapidly and the research behind its clinical applications is steadily growing, especially as accessibility improves. This review also is an updated summary of the current literature on the effectiveness of VR therapy during PD rehabilitation.

Methods

Starting in July 2019, the authors searched several databases (PubMed, Google Scholar, Cochrane, and the Physiotherapy Evidence Database [PEDro]) for articles by using the keyword “Parkinson’s disease” combined with either “virtual reality” or “video games.” To find studies specific to rehabilitation, searches included the additional keyword: “rehabilitation.” After compiling an initial set of 89 articles, titles were reviewed to eliminate duplicates. The authors then read the abstracts to exclude study protocols, systematic reviews, and studies that used VR but did not focus on PD or any therapeutic outcome.

Articles were sorted into immersive or nonimmersive virtual reality categories. To be included as immersive VR, studies had to use any type of VR headset or full-scale VR room. Anything less immersive or similar to a traditional video game was included in the nonimmersive VR category. Articles that met inclusion criteria were selected for the systematic review. Criteria for inclusion in this review were: (1) English language; (2) included a study population focused on PD; (3) used some form of VR therapy; and (4) assessed potential rehabilitation by quantitative outcome measures. Only articles published in peer-reviewed journals were included.

Data were extracted into 2 tables specifically modified for this review: immersive and nonimmersive VR. Extracted data included study author name and publication date, study design, methodologic quality, sample size and group allocation, symptom progression via the Hoehn and Yahr Scale (1 to 5), VR modality, presence of control groups, primary outcomes, and primary findings.

Results

This review is reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA).¹⁰ After screening and assessment, 28 articles met inclusion criteria for this review: 7 using immersive VR and 21 using nonimmersive VR (Figure). The immersive studies included 2 RCTs (both with PEDro scores of 5), 1 controlled study with a PEDro score of 5, 1 pre-post pilot study, and 3 cohort studies (Table 2). The nonimmersive studies included 13 RCTs with an average PEDro score of 5.8; 2 pre-post pilot studies, 1 repeated measures study with a historic control, 1 non-RCT, 2 pre-post prospective studies, and 2 cohort studies (1 retrospective and 1 prospective) (Table 3).

Several outcome and assessment tools were used; the most common measures were related to gait, balance, kinematics, and VR feasibility. Studies varied in VR modalities and protocol, ranging from 21 sessions of Nintendo Wii Fit gaming for 7 weeks to 1 session of VR headset use.

Immersive VR

There were fewer immersive VR studies and these studies had lower mean PEDro scores when compared with nonimmersive VR studies. The VR modalities in the immersive studies used a VR headset or a multisensory immersive system that included polarized glasses. All the studies showed positive improvement in primary outcomes with the exception of Ma and colleagues,which showed no difference in success rates or kinematics with moving balls, and only showed improvement in reaching for stationary balls.¹¹ The mean number of participants in the studies was 18.4.

All 7 studies had each participant complete tasks without VR then with the VR therapy. None of the studies compared immersive VR therapy with more conventional therapies. Robles-Garcia and colleagues compared 2 VR groups where the experimental group imitated an avatar’s finger tapping in the VR system while the control group lacked this imitation.¹² The authors found that adding that imitation to the VR group lead to an increase in movement amplitude.

Among the immersive VR studies, only Janeh and colleagues commented on possible adverse effects (AEs) and found that VR was a safe method without AEs of discomfort or simulator sickness.¹³ The other 6 studies did not make any mention or discussion of AEs related to the training.

Nonimmersive VR

VR modalities used in nonimmersive studies included consumer video gaming systems. Nintendo Wii and Microsoft Xbox Kinect were most commonly used. Among the 21 studies, 14 compared VR therapy with a type of traditional exercise (eg, treadmill training, stretching exercises, balance training). The mean number of participants of the studies was 28.3.

Five studies showed a difference between the VR and traditional training groups.^14-18 However, 9 studies showed positive improvement in both groups and found no between-group differences.^19-25 Among the remaining 7 studies, all showed improvement in primary outcomes after adding VR interventional therapy. In 1 RCT, 3 groups were compared (no intervention, Nintendo Wii, and Xbox Kinect) for gait tests, anxiety levels, memory, and attention.²⁶ The authors found that only the Nintendo Wii group showed improvement in outcomes. A prospective cohort study was the only one to compare different doses of VR therapy (10 sessions vs 15 sessions of Nintendo Wii Fit).²⁷ The authors found that both groups demonstrated the same amount of improvement on balance performances with no group effect.

Ten studiesreported no AEs during the training, but also did not define what was considered an AE.^{15,16,19,22-25,27-29} Eight studies did not make any mention of AEs.^{14,17,21,26,27,30-32} Yen and colleagues reported no AEs during training except for the patients’ tendency to fall.²⁰ However, therapists supervised the patients to avoid falls and no falls occurred. Nuic and colleaguesreported 3 serious AEs, unrelated to the training: severe pneumonia (n = 1) and deep-brain stimulation generator replacement (n = 2).³³ During the video game training sessions no specific AEs occurred. Only Pompeu and colleagues defined an AE as any untoward medical occurrence such as convulsion, syncope, dizziness, vertigo, falls, or any medical condition that required hospitalization or disability.³⁴ One researcher registered the occurrence of any AE; however, none occurred during the study period.

Discussion

This systematic review demonstrates that VR therapy is a promising addition to rehabilitation for PD. Evidence supporting VR therapy is limited, but is continually expanding, and current evidence has shown improvement in assessments and rehabilitative outcomes involving PD. Most nonimmersive studies have shown that VR therapy does not lead to better outcomes when compared with traditional therapy but also is not harmful and does provide similar improvement. Immersive VR studies, on the other hand, have not compared therapy with conventional training extensively, and tend to focus more on time for task completion or movement.

There were fewer immersive VR studies than nonimmersive VR studies. This could be because of the increased technological difficulty and demand to correctly execute immersive VR modalities, as well as the—until recently—substantial expense. This might be another reason why the mean PEDro scores for immersive VR RCTs were lower than the mean scores found in nonimmersive RCTs.

Limitations

This review was limited by several factors related to the included studies. A variety of rating scales were used in the immersive and nonimmersive VR studies. Although there was some general overlap with common measurements such as gait, balance, kinematics, and VR feasibility, no studies had the same primary and secondary outcomes. Such heterogeneity in protocols and outcomes limited our ability to draw conclusions from these differing studies. Additionally, the average number of participants of both immersive and nonimmersive studies were small and the statistical significance of findings should be interpreted with caution. Finally, VR devices and systems differed between studies, further limiting comparisons. Although these factors limit this systematic review, we can still identify treatment and research implications. Adequately powered future studies with standardized protocols would further improve the available evidence and support for VR as an intervention.

Conclusions

VR therapy is a promising rehabilitation modality for PD. Additional investigations of VR therapy and PD should include direct comparisons between immersive and nonimmersive VR therapies. It could be hypothesized that the greater immersion and engagement potential of immersive VR would demonstrate greater functional improvement compared with nonimmersive VR, but there is no data to support this for PD. VR therapy for PD appears to be a relatively safe alternative or adjunct to traditional therapy with a potentially positive impact on a variety of symptoms and is growing as an innovative therapeutic approach for PD patients.

Parkinson disease (PD) is the second most common neurodegenerative disorder after Alzheimer disease.¹ Age-standardized incidence rates of PD in population-based studies in Europe and the United States range from 8.6 to 19.0 per 100,000 individuals, using a strict diagnostic criterion for PD.² The negative impact of PD on health-related quality of life imposes a heavy burden on veterans. According to the US Department of Veterans Affairs (VA) National Parkinson’s Disease Consortium, the VA has as many as 50,000 patients with PD under its care. Because of this demand, the VA has strived to revolutionize available services for veterans with PD and related movement disorders.³

The classic motor symptoms of resting tremors, bradykinesia, postural instability, and rigidity of this progressive neurodegenerative disorder is a significant cause of functional limitations that lead to increased falls and inability to perform activities of daily living that challenges the individual and caregiver. ⁴ Rehabilitation has been considered as an adjuvant to surgical and medical treatments for PD to maximize function and minimize complications. High-intensity multimodal exercise boot camps and therapy that focuses on intensely exercising high-amplitude movements, have been shown to improve motor performance in PD.^5,6 Available evidence has shown that exercise-dependent plasticity is the main mechanism underlying the effects of physiotherapy because it increases synaptic strength and affects neurotransmission.⁷ Although there is no consensus on the optimal approach for rehabilitation, innovative techniques have been proposed and studied. One such approach involves virtual reality (VR), which has begun to attract attention for its potential use during rehabilitation.⁸

VR is a simulated experience created by computer-based technology that grants users access to a virtual environment. There are 2 categories of VR: immersive and nonimmersive. Immersive VR is the most direct experience of virtual environments and usually is implemented through a head-mounted display. These displays have monitors in front of each eye, which can provide monocular or biocular imaging with the most common display being small liquid crystal display (LCD) panels.

Nonimmersive VR typically allows a participant to view a virtual environment by using standard high-resolution monitors rather than a headset or an immersive screen room. Many systems are readily available to the general public as electronic interactive entertainment (ie, video games). Interaction with the virtual world happens through interfaces such as keyboards and controllers while viewing a television or computer monitor. These systems often are more accessible and affordable when compared with immersive VR, although this is changing rapidly.

VR therapy is a noninvasive therapeutic alternative modality for PD. This review aims to study the use of VR to treat PD from a rehabilitative standpoint. Although not the only review on the topic, this systematic review is the first to examine the differences between immersive and nonimmersive VR rehabilitation for PD. VR technology is evolving rapidly and the research behind its clinical applications is steadily growing, especially as accessibility improves. This review also is an updated summary of the current literature on the effectiveness of VR therapy during PD rehabilitation.

Methods

Starting in July 2019, the authors searched several databases (PubMed, Google Scholar, Cochrane, and the Physiotherapy Evidence Database [PEDro]) for articles by using the keyword “Parkinson’s disease” combined with either “virtual reality” or “video games.” To find studies specific to rehabilitation, searches included the additional keyword: “rehabilitation.” After compiling an initial set of 89 articles, titles were reviewed to eliminate duplicates. The authors then read the abstracts to exclude study protocols, systematic reviews, and studies that used VR but did not focus on PD or any therapeutic outcome.

Articles were sorted into immersive or nonimmersive virtual reality categories. To be included as immersive VR, studies had to use any type of VR headset or full-scale VR room. Anything less immersive or similar to a traditional video game was included in the nonimmersive VR category. Articles that met inclusion criteria were selected for the systematic review. Criteria for inclusion in this review were: (1) English language; (2) included a study population focused on PD; (3) used some form of VR therapy; and (4) assessed potential rehabilitation by quantitative outcome measures. Only articles published in peer-reviewed journals were included.

Data were extracted into 2 tables specifically modified for this review: immersive and nonimmersive VR. Extracted data included study author name and publication date, study design, methodologic quality, sample size and group allocation, symptom progression via the Hoehn and Yahr Scale (1 to 5), VR modality, presence of control groups, primary outcomes, and primary findings.

Results

This review is reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA).¹⁰ After screening and assessment, 28 articles met inclusion criteria for this review: 7 using immersive VR and 21 using nonimmersive VR (Figure). The immersive studies included 2 RCTs (both with PEDro scores of 5), 1 controlled study with a PEDro score of 5, 1 pre-post pilot study, and 3 cohort studies (Table 2). The nonimmersive studies included 13 RCTs with an average PEDro score of 5.8; 2 pre-post pilot studies, 1 repeated measures study with a historic control, 1 non-RCT, 2 pre-post prospective studies, and 2 cohort studies (1 retrospective and 1 prospective) (Table 3).

Several outcome and assessment tools were used; the most common measures were related to gait, balance, kinematics, and VR feasibility. Studies varied in VR modalities and protocol, ranging from 21 sessions of Nintendo Wii Fit gaming for 7 weeks to 1 session of VR headset use.

Immersive VR

There were fewer immersive VR studies and these studies had lower mean PEDro scores when compared with nonimmersive VR studies. The VR modalities in the immersive studies used a VR headset or a multisensory immersive system that included polarized glasses. All the studies showed positive improvement in primary outcomes with the exception of Ma and colleagues,which showed no difference in success rates or kinematics with moving balls, and only showed improvement in reaching for stationary balls.¹¹ The mean number of participants in the studies was 18.4.

All 7 studies had each participant complete tasks without VR then with the VR therapy. None of the studies compared immersive VR therapy with more conventional therapies. Robles-Garcia and colleagues compared 2 VR groups where the experimental group imitated an avatar’s finger tapping in the VR system while the control group lacked this imitation.¹² The authors found that adding that imitation to the VR group lead to an increase in movement amplitude.

Among the immersive VR studies, only Janeh and colleagues commented on possible adverse effects (AEs) and found that VR was a safe method without AEs of discomfort or simulator sickness.¹³ The other 6 studies did not make any mention or discussion of AEs related to the training.

Nonimmersive VR

VR modalities used in nonimmersive studies included consumer video gaming systems. Nintendo Wii and Microsoft Xbox Kinect were most commonly used. Among the 21 studies, 14 compared VR therapy with a type of traditional exercise (eg, treadmill training, stretching exercises, balance training). The mean number of participants of the studies was 28.3.

Five studies showed a difference between the VR and traditional training groups.^14-18 However, 9 studies showed positive improvement in both groups and found no between-group differences.^19-25 Among the remaining 7 studies, all showed improvement in primary outcomes after adding VR interventional therapy. In 1 RCT, 3 groups were compared (no intervention, Nintendo Wii, and Xbox Kinect) for gait tests, anxiety levels, memory, and attention.²⁶ The authors found that only the Nintendo Wii group showed improvement in outcomes. A prospective cohort study was the only one to compare different doses of VR therapy (10 sessions vs 15 sessions of Nintendo Wii Fit).²⁷ The authors found that both groups demonstrated the same amount of improvement on balance performances with no group effect.

Ten studiesreported no AEs during the training, but also did not define what was considered an AE.^{15,16,19,22-25,27-29} Eight studies did not make any mention of AEs.^{14,17,21,26,27,30-32} Yen and colleagues reported no AEs during training except for the patients’ tendency to fall.²⁰ However, therapists supervised the patients to avoid falls and no falls occurred. Nuic and colleaguesreported 3 serious AEs, unrelated to the training: severe pneumonia (n = 1) and deep-brain stimulation generator replacement (n = 2).³³ During the video game training sessions no specific AEs occurred. Only Pompeu and colleagues defined an AE as any untoward medical occurrence such as convulsion, syncope, dizziness, vertigo, falls, or any medical condition that required hospitalization or disability.³⁴ One researcher registered the occurrence of any AE; however, none occurred during the study period.

Discussion

This systematic review demonstrates that VR therapy is a promising addition to rehabilitation for PD. Evidence supporting VR therapy is limited, but is continually expanding, and current evidence has shown improvement in assessments and rehabilitative outcomes involving PD. Most nonimmersive studies have shown that VR therapy does not lead to better outcomes when compared with traditional therapy but also is not harmful and does provide similar improvement. Immersive VR studies, on the other hand, have not compared therapy with conventional training extensively, and tend to focus more on time for task completion or movement.

There were fewer immersive VR studies than nonimmersive VR studies. This could be because of the increased technological difficulty and demand to correctly execute immersive VR modalities, as well as the—until recently—substantial expense. This might be another reason why the mean PEDro scores for immersive VR RCTs were lower than the mean scores found in nonimmersive RCTs.

Limitations

This review was limited by several factors related to the included studies. A variety of rating scales were used in the immersive and nonimmersive VR studies. Although there was some general overlap with common measurements such as gait, balance, kinematics, and VR feasibility, no studies had the same primary and secondary outcomes. Such heterogeneity in protocols and outcomes limited our ability to draw conclusions from these differing studies. Additionally, the average number of participants of both immersive and nonimmersive studies were small and the statistical significance of findings should be interpreted with caution. Finally, VR devices and systems differed between studies, further limiting comparisons. Although these factors limit this systematic review, we can still identify treatment and research implications. Adequately powered future studies with standardized protocols would further improve the available evidence and support for VR as an intervention.

Conclusions

VR therapy is a promising rehabilitation modality for PD. Additional investigations of VR therapy and PD should include direct comparisons between immersive and nonimmersive VR therapies. It could be hypothesized that the greater immersion and engagement potential of immersive VR would demonstrate greater functional improvement compared with nonimmersive VR, but there is no data to support this for PD. VR therapy for PD appears to be a relatively safe alternative or adjunct to traditional therapy with a potentially positive impact on a variety of symptoms and is growing as an innovative therapeutic approach for PD patients.

Surgical treatment of degenerative lumbar spine disease has been rising steadily in the United States, and an increasing fraction of surgery involves lumbar fusion.^1,2 Various techniques are used to accomplish a lumbar fusion, including noninstrumented fusion, anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (XLIF, OLIF), posterior pedicle screw fusion, posterior cortical screw fusion, posterior interbody fusion (TLIF, PLIF), and interspinous process fusion. Rigid, metallic fusion hardware provides high stability and fusion rates, but it likely leads to stress shielding and adjacent segment disease.³ There is interest in less rigid and dynamic stabilization techniques to reduce the risk of adjacent segment disease, such as polyetheretherketone (PEEK) rods, which have been available since 2007. However, literature regarding PEEK rod utility is sparse and of mixed outcomes.^3,4 Additional patient reported outcome (PRO) information would be useful to both surgeons and patients. Using institutional data, this review was designed to examine our experience with PEEK rod lumbar fusion and to document PROs.

Methods

The study was approved by the institutional review board at the US Department of Veterans Affairs (VA) Portland Health Care System (VAPHCS) in Oregon with a waiver of authorization. In this retrospective, single center study, data were queried from the senior author’s (DAR) case logs from VA Computerized Patient Record System (CPRS). Electronic medical records, imaging, and PROs of all consecutive patients undergoing lumbar fusion at 1 or 2 levels with PEEK rods for degenerative disease were retrospectively reviewed. Cases of trauma, malignancy, or infection were excluded. From March 2011 through October 2019, 108 patients underwent lumbar fusion with PEEK rods.

Surgeries were conducted on a Mizuho OSI Jackson Table via bilateral 3 to 4 cm Wiltse incisions using the Medtronic Quadrant retractor system. Medtronic O-Arm images were acquired and delivered to a Medtronic Stealth Station for navigation of the screws. Monopolar coagulation was not used. PEEK pedicle screws were placed and verified with a second O-Arm spin before placing lordotic PEEK rods in the screw heads. No attempt was made to reduce any spondylolisthesis, but distraction was used to open the foramina and indirectly decompress the canal. An interbody device was placed only in treatment of multiply recurrent disc protrusion. After decortication of the transverse processes and facets, intertransverse fusion constructs consisting of calcium hydroxyapatite soaked in autologous bone marrow blood and wrapped in 6-mg bone morphogenetic protein-soaked sponges were placed on the bone. If canal decompression was indicated, a Medtronic Metrx retractor tube was then placed through one of the incisions and decompression carried out. Wounds were closed with absorbable suture. No bracing was used postoperatively. Figure 1 shows a typical single level PEEK rod fusion construct.

Statistical Analysis

Pre- and postoperative pairwise t tests were completed for patients with a complete data, using SAS 9.2 statistical package. Data are presented as standard deviation (SD) of the mean.

Results

Following application of the inclusion/exclusion criteria, 108 patients had undergone lumbar fusion with PEEK rods. Mean (SD) patient age was 60.2 (10.3) years and 88 patients were male (Table 1). Most surgeries were at L5-S1 and L4-5. There were 97 single-level fusions and 11 bilevel fusions. Seventy-four procedures were for spondylolisthesis, 23 for foraminal stenosis, 5 for degenerative disc disease, 3 for coronal imbalance with foraminal stenosis, 2 for pseudarthrosis after surgery elsewhere, and 1 for multiple recurrent disc herniation (Table 2). Twenty-five patients (23.1%) were current tobacco users and 28 (25.9%) were former smokers, 26 (24.1%) had diabetes mellitus (DM), 16 (14.8%) had low bone density by dual energy X-ray absorptiometry (DEXA) imaging, 35 (32.4%) had depression, and 7 (6.5%) were taking an immunosuppressive agent (chronic steroids, biological response modifiers, or methotrexate). Mean body mass index was 30.1.

Surgical Procedure

Of the 108 patients, the first 18 underwent a procedure with fluoroscopic guidance and the Medtronic FluoroNav and Stealth Systems. The next 90 patients underwent a procedure with O-Arm intraoperative CT scanning and Stealth frameless stereotactic navigation. The mean (SD) length of stay was 1.7 (1.3) days. There were no wound infections and no new neurologic deficits. Mean (SD) follow up time was 30.3 (21.8) months.

Imaging

Final imaging was by radiograph in 73 patients, CT in 31, and magnetic resonance imaging (MRI) in 3 (1 patient had no imaging). Sixty-seven patients (62.0%) had a bilateral arthrodesis, and 15 (13.9%) had at least a unilateral arthrodesis. MRI was not used to assess arthrodesis. Eight patients (7.4%) had no definite arthrodesis. Seventeen patients had inadequate or early imaging from which a fusion determination could not be made. Of 81 patients with > 11 months of follow up, 58 (71.6%) had a bilateral arthrodesis, 12 (14.8%) had a unilateral arthrodesis, 8 (9.9%) had no arthrodesis, and 3 (3.7%) were indeterminate.

No patient had any revision fusion surgery at the index level during follow up. Two patients had adjacent level fusions at 27 and 60 months after the index procedure. One patient had a laminectomy at an adjacent segment at 18 months postfusion, and 1 had a foraminotomy at an adjacent segment 89 months post fusion (Figure 3). Overall, there were 4 (3.7%) adjacent segment surgeries at a mean of 48.5 months after surgery. One patient had a sacro-iliac joint fusion below an L5-S1 fusion 17 months prior for persisting pain after the fusion procedure.

Patient Reported Outcomes

Preoperative SF-36 PF and ODI scores were available for 81 patients (Table 3). Postoperative SF-36 PF scores were obtained at 3 months for 65 of these patients, and at 1 year for 63 patients. Postoperative ODI scores were obtained at 3 months for 65 patients, and at 1 year for 55 patients. Among the 65 patients with completed SF-36 scores at 3 months, a mean increase of 22.4 (95% CI, 17-27; P < .001) was noted, and for the 63 patients at 1 year a mean increase of 30.3 (95% CI, 25-35; P < .001) was noted. Among the 65 patients with completed ODI scores at 3 months, a mean decrease of 6.8 (95% CI, 4.9-8.6; P < .001) was noted, and for the 55 patients with completed ODI scores at 1 year a mean decrease of 10.3 (n = 55; 95% CI, 8.4-12.2; P < .001) was noted.

Cost

We compared the hardware cost of a single level construct consisting of 4 pedicle screws, 4 locking caps, and 2 rods using a PEEK system with that of 2 other titanium construct systems. At VAPHCS, the PEEK system cost was about 71% of the cost of 2 other titanium construct systems and 62% of the cost when compared with Medtronic titanium rods.

Discussion

PEEK is useful for spine and cranial implants. It is inert and fully biocompatible with a modulus of elasticity between that of cortical and cancellous bone, and much lower than that of titanium, and is therefore considered to be semirigid.^3,4,6 PEEK rods are intermediate in stiffness between titanium rods (110 Gigapascals) and dynamic devices such as the Zimmer Biomet DYNESYS dynamic stabilization system or the Premia Spine TOPS system.³ Carbon fiber rods and carbon fiber reinforced PEEK implants are other semirigid rod alternatives.^7,8 PEEK rods for posterior lumbar fusion surgery were introduced in 2007. Li and colleagues provide a thorough review of the biomechanical properties of PEEK rods.³

PEEK is thought to have several advantages when compared with titanium. These advantages include more physiologic load sharing and reduction in stress shielding, improved durability, reduced risk of failure in osteoporotic bone, less wear debris, no change in bone forming environment, and imaging radiolucency.^4,9 Spinal PEEK cages have been reported to allow more uniform radiation dose distribution compared with metal constructs, an advantage that also may pertain to PEEK rods.¹⁰ Disadvantages of PEEK rods include an inability to detect rod breakage easily, lack of data on the use in more than minimally unstable clinical situations, and greater expense, although this was not the authors’ observation.^3,4,11

Importantly, it has been reported that PEEK rods permit a greater range of motion in all planes when compared with titanium rods.⁹ Polyetheretherketone rods unload the bone screw interface and increased the anterior column load to a more physiologic 75% when compared with titanium rods.^6,9 However, in another biomechanical study that compared titanium rods, PEEK rods, and a dynamic stabilization device, it was reported that anterior load sharing was 55%, 59%, and 75%, respectively.¹² This indicated that PEEK rods are closer to metal rods than truly dynamic devices for anterior load sharing. The endurance limit of a PEEK rod construct was similar to that of clinically useful metal systems.⁹ PEEK rods resulted in no increase in postfatigue motion compared with titanium rods in a biomechanical model.¹³ Intradiscal pressures at PEEK instrumented segments were similar to uninstrumented segments and greater than those with titanium rod constructs.¹⁴ Intradiscal pressures at adjacent segments were highest with dynamic devices, intermediate with semirigid rods, and lowest with rigid constructs; however, stress values at adjacent segments were lower in PEEK than titanium constructs in any direction of motion.^15,16

Fusion Rates

The use of PEEK rods in lumbar fusion has been reported previously.^3,4,17,18 However, these studies featured small sample sizes, short follow up times, and contradictory results.⁴ Of 8 outcome reports found in a systematic review, 2 studies reported on procedures designed to create nonfusion outcomes (a third similar trial from 2013 was not included in the systematic review), and 1 study reported only on the condition of PEEK rods removed at subsequent surgery.^3,19-21 Reported fusion rates varied from 86 to 100%.

In 42 patients with PEEK rod fusions who were followed for a mean of 31.4 months, 5 patients required adjacent segment surgery and 3 patients were treated for interbody cage migration and nonunion.¹⁷ Radiographic fusion rate was 86%. These authors concluded that PEEK rod fusion results were similar to those of other constructs, but not better, or perhaps worse than, metal rods.

Other studies have reported better results with PEEK.^{11,18,19,22-24} Highsmith and colleagues reported on 3 successful example cases of the use of PEEK rods.¹¹ De Iure and colleagues reported on 30 cases up to 5 levels (mean, 2.9) using autograft bone, with a mean follow up of 18 months.²³ Results were reported as satisfactory. Three patients had radiographic nonunions, 1 of which required revision for asymptomatic screw loosening at the cranial end of the construct. Qi and colleagues, reported on 20 patients with PEEK rods compared to 21 patients with titanium alloy rods.²⁴ Both groups had similar clinical outcomes, structural parameters, and 100% fusion rates. Athanasakopoulos and colleagues reported on 52 patients with up to 3 level fusions followed for a mean of 3 years.²² There were significant improvements in PROs: at 1 year 96% had radiographic union. Two patients had screw breakage, 1 of whom required revision to a metal rod construct. Colangeli and colleagues reported on 12 patients treated with PEEK rods compared with 12 who were treated with a dynamic system.¹⁸ They reported significant improvements, no complications, and 100% fusion at 6 months. Huang and colleagues reported on 38 patients intended to undergo a nonfusion procedure with 2 years of follow up.¹⁹ They reported good outcomes and 1 case of screw loosening. As no fusion was intended, no fusion outcomes were reported. All these studies suggested that longer follow up and more patients would be needed to assess the role of PEEK rods in lumbar fusion.³

Our results show a radiographic fusion rate of 86.4% and a radiographic nonunion rate of 9.9% in patients followed for at least 12 months. There was no clinical need for revision fusion at the index level. In our retrospective review, patients had high levels of smoking, DM, depression, immunosuppression, and obesity, which may negatively influence radiographic fusion rates when compared with other studies with 100% reported fusion rates. There was no instance of construct breakage or screw breakout, indicating that PEEK rods may allow enough flexibility to avoid construct failure under stress as in a fall.

Patient Reported Outcomes

Recent large studies were reviewed to assess the pre- and postoperative patient PROs reported in comparison with our study population (Table 4). In the Swedish Spine Registry analysis of 765 patients with 3 different types of lumbar fusion, the mean preoperative ODI score was 37 and mean SF-36 physical component score (PCS) was 35 for the most similar approach (posterolateral fusion with instrumentation).²⁵ At 1 year postoperation, the mean ODI was 26 and mean SF-36 PCS was 43. In the Spine Patient Outcomes Research Trial (SPORT) spondylolisthesis trial of 3 fusion types, the mean preoperative ODI was 41.2 and mean SF-36 PF score was 31.2 for the most similar approach (posterolateral instrumented fusion with pedicle screws).²⁶ Postoperative ODI scores at 1 year decreased by a mean 20.9 points and mean SF-36 PF scores increased by 29.9.

We report a mean preoperative SF-36 PF score of 28.9, which is lower than the SPORT study score for posterolateral fusion with instrumentation and the Swedish Study score for posterolateral instrumented fusion with pedicle screws. Similarly, our mean ODI score of 24.8 was better than the scores reported in the Swedish and SPORT studies. Our mean SF-36 PF score at 1 year postoperation was 59.3, compared with 58.5 for the SPORT study group and 46.0 in the Swedish study group. Mean ODI score at 1 year postoperatively was 14.5, which is better than the scores reported in the Swedish and SPORT studies.

Minimally clinically important difference (MCID) is a parameter used to gauge the efficacy of spine surgery. The utility of the MCID based upon PROs has been questioned in lumbar fusion surgery, as it has been thought to measure if the patient is “feeling” rather than “doing” better, the latter of which can be better measured by functional performance measures and objective, external socioeconomic anchors such as return to work and health care costs.²⁷ Nevertheless, validated PROs are reported widely in the spine surgery literature. The MCID in the SF-36 is not well established and can depend upon whether the scores are at the extremes or more in the central range and whether there is large variability in the scores.²⁸ Rheumatoid arthritis was estimated to be 7.1 points on the PF scale and 7.2 on the physical component summary (PCS).²⁹ For total knee replacement, it has been estimated to be 10 points on the SF-36 PCS.³⁰ Lumbar surgery was estimated to be 4.9 points for the SF-36 PCS and 12.8 points for the ODI.³¹ And the SPORT trial it has been estimated that a 30% change in the possible gain (or loss) may be an appropriate criterion.²⁸

With a preoperative mean SF-36 PF of 28.9, a 30% improvement in the available range (70.1) would be 21 points, making our data mean improvement of 30 points above the MCID. With a mean preoperative ODI of 24.6, a 30% improvement in the available range (25.4) would be 7.6 points, making our data mean improvement of 10.3 points better than the MCID. Therefore, our outcome results are comparable with other lumbar fusion outcome studies in terms of degree of disability prior to surgery and amount of improvement from surgery.

Adjacent Segment Disease

The precise factors resulting in adjacent segment disease are not fully defined.^3,32 In reviews of lumbar adjacent segment disease, reported rates ranged from 2.5% at 1 year up to 80 to 100% at 10 years, with lower rates with noninstrumented fusions.^4,32-34 Annual incidence of symptomatic adjacent segment disease following lumbar fusion ranges from 0.6 to 3.9% per year.^32,35,36 Mismatch between lumbar lordosis and pelvic incidence after fusion is thought to lead to higher rates of adjacent segment disease, as can a laminectomy at an adjacent segment.^32,36 Percutaneous fusion techniques or use of the Wiltse approach may lower the risk of adjacent segment disease due to avoidance of facet capsule disruption.^37,38

Dynamic stabilization techniques do not appear be clearly protective against adjacent segment disease, although biomechanical models suggest that they may do so.^33,39,40 A review by Wang and colleagues pooled studies to assess the risk of lumbar adjacent segment disease in spinal fusion to compare to disc arthroplasty and concluded that fusion carried a higher risk of adjacent segment disease.⁴¹ Definitive data on other types of motion preservation devices is lacking.³We show 3 adjacent segment fusions and 1 laminectomy have been needed in 108 patients and at a mean of 46 months after the index procedure and over 2.5 years of mean overall follow up. This is a low adjacent segment surgery rate compared to the historical data cited above, and may suggest some advantage for PEEK rods over more rigid constructs.

Strengths and Limitations

Strengths of this study include larger numbers than prior series of PEEK rod use and use in a population with high comorbidities linked to poor results without reduction in good outcomes. PEEK rods as used at the VAPHCS do not result in higher instrumentation costs than all metal constructs.

Study limitations include the retrospective nature with loss of follow up on some patients and incomplete radiographic and PROs in some patients. The use of 100% stereotactic guidance, the avoidance of interbody devices, and the off-label use of bone morphogenetic protein as part of the fusion construct introduce additional variables that may influence comparison to other studies. To avoid unnecessary radiation exposure, flexion extension films or CT scans were not routinely obtained if patients were doing well.⁴² Additionally, the degree of motion on dynamic views that would differentiate pseudarthrosis from arthrodesis has not been defined.⁵

Conclusions

The results presented show that lumbar fusion with PEEK rods can be undertaken with short hospitalization times and low complication rates, produce satisfactory clinical improvements, and result in radiographic fusion rates similar to metal constructs. Low rates of hardware failure or need for revision surgery were found. Preliminarily results of low rates of adjacent segment surgery are comparable with previously published metal construct rates. Longer follow up is needed to confirm these findings and to investigate whether semirigid constructs truly offer some protection from adjacent segment disease when compared to all metal constructs.

Acknowledgments
The authors thank Shirley McCartney, PhD, for editorial assistance.

Surgical treatment of degenerative lumbar spine disease has been rising steadily in the United States, and an increasing fraction of surgery involves lumbar fusion.^1,2 Various techniques are used to accomplish a lumbar fusion, including noninstrumented fusion, anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (XLIF, OLIF), posterior pedicle screw fusion, posterior cortical screw fusion, posterior interbody fusion (TLIF, PLIF), and interspinous process fusion. Rigid, metallic fusion hardware provides high stability and fusion rates, but it likely leads to stress shielding and adjacent segment disease.³ There is interest in less rigid and dynamic stabilization techniques to reduce the risk of adjacent segment disease, such as polyetheretherketone (PEEK) rods, which have been available since 2007. However, literature regarding PEEK rod utility is sparse and of mixed outcomes.^3,4 Additional patient reported outcome (PRO) information would be useful to both surgeons and patients. Using institutional data, this review was designed to examine our experience with PEEK rod lumbar fusion and to document PROs.

Methods

The study was approved by the institutional review board at the US Department of Veterans Affairs (VA) Portland Health Care System (VAPHCS) in Oregon with a waiver of authorization. In this retrospective, single center study, data were queried from the senior author’s (DAR) case logs from VA Computerized Patient Record System (CPRS). Electronic medical records, imaging, and PROs of all consecutive patients undergoing lumbar fusion at 1 or 2 levels with PEEK rods for degenerative disease were retrospectively reviewed. Cases of trauma, malignancy, or infection were excluded. From March 2011 through October 2019, 108 patients underwent lumbar fusion with PEEK rods.

Surgeries were conducted on a Mizuho OSI Jackson Table via bilateral 3 to 4 cm Wiltse incisions using the Medtronic Quadrant retractor system. Medtronic O-Arm images were acquired and delivered to a Medtronic Stealth Station for navigation of the screws. Monopolar coagulation was not used. PEEK pedicle screws were placed and verified with a second O-Arm spin before placing lordotic PEEK rods in the screw heads. No attempt was made to reduce any spondylolisthesis, but distraction was used to open the foramina and indirectly decompress the canal. An interbody device was placed only in treatment of multiply recurrent disc protrusion. After decortication of the transverse processes and facets, intertransverse fusion constructs consisting of calcium hydroxyapatite soaked in autologous bone marrow blood and wrapped in 6-mg bone morphogenetic protein-soaked sponges were placed on the bone. If canal decompression was indicated, a Medtronic Metrx retractor tube was then placed through one of the incisions and decompression carried out. Wounds were closed with absorbable suture. No bracing was used postoperatively. Figure 1 shows a typical single level PEEK rod fusion construct.

Statistical Analysis

Pre- and postoperative pairwise t tests were completed for patients with a complete data, using SAS 9.2 statistical package. Data are presented as standard deviation (SD) of the mean.

Results

Following application of the inclusion/exclusion criteria, 108 patients had undergone lumbar fusion with PEEK rods. Mean (SD) patient age was 60.2 (10.3) years and 88 patients were male (Table 1). Most surgeries were at L5-S1 and L4-5. There were 97 single-level fusions and 11 bilevel fusions. Seventy-four procedures were for spondylolisthesis, 23 for foraminal stenosis, 5 for degenerative disc disease, 3 for coronal imbalance with foraminal stenosis, 2 for pseudarthrosis after surgery elsewhere, and 1 for multiple recurrent disc herniation (Table 2). Twenty-five patients (23.1%) were current tobacco users and 28 (25.9%) were former smokers, 26 (24.1%) had diabetes mellitus (DM), 16 (14.8%) had low bone density by dual energy X-ray absorptiometry (DEXA) imaging, 35 (32.4%) had depression, and 7 (6.5%) were taking an immunosuppressive agent (chronic steroids, biological response modifiers, or methotrexate). Mean body mass index was 30.1.

Surgical Procedure

Of the 108 patients, the first 18 underwent a procedure with fluoroscopic guidance and the Medtronic FluoroNav and Stealth Systems. The next 90 patients underwent a procedure with O-Arm intraoperative CT scanning and Stealth frameless stereotactic navigation. The mean (SD) length of stay was 1.7 (1.3) days. There were no wound infections and no new neurologic deficits. Mean (SD) follow up time was 30.3 (21.8) months.

Imaging

Final imaging was by radiograph in 73 patients, CT in 31, and magnetic resonance imaging (MRI) in 3 (1 patient had no imaging). Sixty-seven patients (62.0%) had a bilateral arthrodesis, and 15 (13.9%) had at least a unilateral arthrodesis. MRI was not used to assess arthrodesis. Eight patients (7.4%) had no definite arthrodesis. Seventeen patients had inadequate or early imaging from which a fusion determination could not be made. Of 81 patients with > 11 months of follow up, 58 (71.6%) had a bilateral arthrodesis, 12 (14.8%) had a unilateral arthrodesis, 8 (9.9%) had no arthrodesis, and 3 (3.7%) were indeterminate.

No patient had any revision fusion surgery at the index level during follow up. Two patients had adjacent level fusions at 27 and 60 months after the index procedure. One patient had a laminectomy at an adjacent segment at 18 months postfusion, and 1 had a foraminotomy at an adjacent segment 89 months post fusion (Figure 3). Overall, there were 4 (3.7%) adjacent segment surgeries at a mean of 48.5 months after surgery. One patient had a sacro-iliac joint fusion below an L5-S1 fusion 17 months prior for persisting pain after the fusion procedure.

Patient Reported Outcomes

Preoperative SF-36 PF and ODI scores were available for 81 patients (Table 3). Postoperative SF-36 PF scores were obtained at 3 months for 65 of these patients, and at 1 year for 63 patients. Postoperative ODI scores were obtained at 3 months for 65 patients, and at 1 year for 55 patients. Among the 65 patients with completed SF-36 scores at 3 months, a mean increase of 22.4 (95% CI, 17-27; P < .001) was noted, and for the 63 patients at 1 year a mean increase of 30.3 (95% CI, 25-35; P < .001) was noted. Among the 65 patients with completed ODI scores at 3 months, a mean decrease of 6.8 (95% CI, 4.9-8.6; P < .001) was noted, and for the 55 patients with completed ODI scores at 1 year a mean decrease of 10.3 (n = 55; 95% CI, 8.4-12.2; P < .001) was noted.

Cost

We compared the hardware cost of a single level construct consisting of 4 pedicle screws, 4 locking caps, and 2 rods using a PEEK system with that of 2 other titanium construct systems. At VAPHCS, the PEEK system cost was about 71% of the cost of 2 other titanium construct systems and 62% of the cost when compared with Medtronic titanium rods.

Discussion

PEEK is useful for spine and cranial implants. It is inert and fully biocompatible with a modulus of elasticity between that of cortical and cancellous bone, and much lower than that of titanium, and is therefore considered to be semirigid.^3,4,6 PEEK rods are intermediate in stiffness between titanium rods (110 Gigapascals) and dynamic devices such as the Zimmer Biomet DYNESYS dynamic stabilization system or the Premia Spine TOPS system.³ Carbon fiber rods and carbon fiber reinforced PEEK implants are other semirigid rod alternatives.^7,8 PEEK rods for posterior lumbar fusion surgery were introduced in 2007. Li and colleagues provide a thorough review of the biomechanical properties of PEEK rods.³

PEEK is thought to have several advantages when compared with titanium. These advantages include more physiologic load sharing and reduction in stress shielding, improved durability, reduced risk of failure in osteoporotic bone, less wear debris, no change in bone forming environment, and imaging radiolucency.^4,9 Spinal PEEK cages have been reported to allow more uniform radiation dose distribution compared with metal constructs, an advantage that also may pertain to PEEK rods.¹⁰ Disadvantages of PEEK rods include an inability to detect rod breakage easily, lack of data on the use in more than minimally unstable clinical situations, and greater expense, although this was not the authors’ observation.^3,4,11

Importantly, it has been reported that PEEK rods permit a greater range of motion in all planes when compared with titanium rods.⁹ Polyetheretherketone rods unload the bone screw interface and increased the anterior column load to a more physiologic 75% when compared with titanium rods.^6,9 However, in another biomechanical study that compared titanium rods, PEEK rods, and a dynamic stabilization device, it was reported that anterior load sharing was 55%, 59%, and 75%, respectively.¹² This indicated that PEEK rods are closer to metal rods than truly dynamic devices for anterior load sharing. The endurance limit of a PEEK rod construct was similar to that of clinically useful metal systems.⁹ PEEK rods resulted in no increase in postfatigue motion compared with titanium rods in a biomechanical model.¹³ Intradiscal pressures at PEEK instrumented segments were similar to uninstrumented segments and greater than those with titanium rod constructs.¹⁴ Intradiscal pressures at adjacent segments were highest with dynamic devices, intermediate with semirigid rods, and lowest with rigid constructs; however, stress values at adjacent segments were lower in PEEK than titanium constructs in any direction of motion.^15,16

Fusion Rates

The use of PEEK rods in lumbar fusion has been reported previously.^3,4,17,18 However, these studies featured small sample sizes, short follow up times, and contradictory results.⁴ Of 8 outcome reports found in a systematic review, 2 studies reported on procedures designed to create nonfusion outcomes (a third similar trial from 2013 was not included in the systematic review), and 1 study reported only on the condition of PEEK rods removed at subsequent surgery.^3,19-21 Reported fusion rates varied from 86 to 100%.

In 42 patients with PEEK rod fusions who were followed for a mean of 31.4 months, 5 patients required adjacent segment surgery and 3 patients were treated for interbody cage migration and nonunion.¹⁷ Radiographic fusion rate was 86%. These authors concluded that PEEK rod fusion results were similar to those of other constructs, but not better, or perhaps worse than, metal rods.

Other studies have reported better results with PEEK.^{11,18,19,22-24} Highsmith and colleagues reported on 3 successful example cases of the use of PEEK rods.¹¹ De Iure and colleagues reported on 30 cases up to 5 levels (mean, 2.9) using autograft bone, with a mean follow up of 18 months.²³ Results were reported as satisfactory. Three patients had radiographic nonunions, 1 of which required revision for asymptomatic screw loosening at the cranial end of the construct. Qi and colleagues, reported on 20 patients with PEEK rods compared to 21 patients with titanium alloy rods.²⁴ Both groups had similar clinical outcomes, structural parameters, and 100% fusion rates. Athanasakopoulos and colleagues reported on 52 patients with up to 3 level fusions followed for a mean of 3 years.²² There were significant improvements in PROs: at 1 year 96% had radiographic union. Two patients had screw breakage, 1 of whom required revision to a metal rod construct. Colangeli and colleagues reported on 12 patients treated with PEEK rods compared with 12 who were treated with a dynamic system.¹⁸ They reported significant improvements, no complications, and 100% fusion at 6 months. Huang and colleagues reported on 38 patients intended to undergo a nonfusion procedure with 2 years of follow up.¹⁹ They reported good outcomes and 1 case of screw loosening. As no fusion was intended, no fusion outcomes were reported. All these studies suggested that longer follow up and more patients would be needed to assess the role of PEEK rods in lumbar fusion.³

Our results show a radiographic fusion rate of 86.4% and a radiographic nonunion rate of 9.9% in patients followed for at least 12 months. There was no clinical need for revision fusion at the index level. In our retrospective review, patients had high levels of smoking, DM, depression, immunosuppression, and obesity, which may negatively influence radiographic fusion rates when compared with other studies with 100% reported fusion rates. There was no instance of construct breakage or screw breakout, indicating that PEEK rods may allow enough flexibility to avoid construct failure under stress as in a fall.

Patient Reported Outcomes

Recent large studies were reviewed to assess the pre- and postoperative patient PROs reported in comparison with our study population (Table 4). In the Swedish Spine Registry analysis of 765 patients with 3 different types of lumbar fusion, the mean preoperative ODI score was 37 and mean SF-36 physical component score (PCS) was 35 for the most similar approach (posterolateral fusion with instrumentation).²⁵ At 1 year postoperation, the mean ODI was 26 and mean SF-36 PCS was 43. In the Spine Patient Outcomes Research Trial (SPORT) spondylolisthesis trial of 3 fusion types, the mean preoperative ODI was 41.2 and mean SF-36 PF score was 31.2 for the most similar approach (posterolateral instrumented fusion with pedicle screws).²⁶ Postoperative ODI scores at 1 year decreased by a mean 20.9 points and mean SF-36 PF scores increased by 29.9.

We report a mean preoperative SF-36 PF score of 28.9, which is lower than the SPORT study score for posterolateral fusion with instrumentation and the Swedish Study score for posterolateral instrumented fusion with pedicle screws. Similarly, our mean ODI score of 24.8 was better than the scores reported in the Swedish and SPORT studies. Our mean SF-36 PF score at 1 year postoperation was 59.3, compared with 58.5 for the SPORT study group and 46.0 in the Swedish study group. Mean ODI score at 1 year postoperatively was 14.5, which is better than the scores reported in the Swedish and SPORT studies.

Minimally clinically important difference (MCID) is a parameter used to gauge the efficacy of spine surgery. The utility of the MCID based upon PROs has been questioned in lumbar fusion surgery, as it has been thought to measure if the patient is “feeling” rather than “doing” better, the latter of which can be better measured by functional performance measures and objective, external socioeconomic anchors such as return to work and health care costs.²⁷ Nevertheless, validated PROs are reported widely in the spine surgery literature. The MCID in the SF-36 is not well established and can depend upon whether the scores are at the extremes or more in the central range and whether there is large variability in the scores.²⁸ Rheumatoid arthritis was estimated to be 7.1 points on the PF scale and 7.2 on the physical component summary (PCS).²⁹ For total knee replacement, it has been estimated to be 10 points on the SF-36 PCS.³⁰ Lumbar surgery was estimated to be 4.9 points for the SF-36 PCS and 12.8 points for the ODI.³¹ And the SPORT trial it has been estimated that a 30% change in the possible gain (or loss) may be an appropriate criterion.²⁸

With a preoperative mean SF-36 PF of 28.9, a 30% improvement in the available range (70.1) would be 21 points, making our data mean improvement of 30 points above the MCID. With a mean preoperative ODI of 24.6, a 30% improvement in the available range (25.4) would be 7.6 points, making our data mean improvement of 10.3 points better than the MCID. Therefore, our outcome results are comparable with other lumbar fusion outcome studies in terms of degree of disability prior to surgery and amount of improvement from surgery.

Adjacent Segment Disease

The precise factors resulting in adjacent segment disease are not fully defined.^3,32 In reviews of lumbar adjacent segment disease, reported rates ranged from 2.5% at 1 year up to 80 to 100% at 10 years, with lower rates with noninstrumented fusions.^4,32-34 Annual incidence of symptomatic adjacent segment disease following lumbar fusion ranges from 0.6 to 3.9% per year.^32,35,36 Mismatch between lumbar lordosis and pelvic incidence after fusion is thought to lead to higher rates of adjacent segment disease, as can a laminectomy at an adjacent segment.^32,36 Percutaneous fusion techniques or use of the Wiltse approach may lower the risk of adjacent segment disease due to avoidance of facet capsule disruption.^37,38

Dynamic stabilization techniques do not appear be clearly protective against adjacent segment disease, although biomechanical models suggest that they may do so.^33,39,40 A review by Wang and colleagues pooled studies to assess the risk of lumbar adjacent segment disease in spinal fusion to compare to disc arthroplasty and concluded that fusion carried a higher risk of adjacent segment disease.⁴¹ Definitive data on other types of motion preservation devices is lacking.³We show 3 adjacent segment fusions and 1 laminectomy have been needed in 108 patients and at a mean of 46 months after the index procedure and over 2.5 years of mean overall follow up. This is a low adjacent segment surgery rate compared to the historical data cited above, and may suggest some advantage for PEEK rods over more rigid constructs.

Strengths and Limitations

Strengths of this study include larger numbers than prior series of PEEK rod use and use in a population with high comorbidities linked to poor results without reduction in good outcomes. PEEK rods as used at the VAPHCS do not result in higher instrumentation costs than all metal constructs.

Study limitations include the retrospective nature with loss of follow up on some patients and incomplete radiographic and PROs in some patients. The use of 100% stereotactic guidance, the avoidance of interbody devices, and the off-label use of bone morphogenetic protein as part of the fusion construct introduce additional variables that may influence comparison to other studies. To avoid unnecessary radiation exposure, flexion extension films or CT scans were not routinely obtained if patients were doing well.⁴² Additionally, the degree of motion on dynamic views that would differentiate pseudarthrosis from arthrodesis has not been defined.⁵

Conclusions

The results presented show that lumbar fusion with PEEK rods can be undertaken with short hospitalization times and low complication rates, produce satisfactory clinical improvements, and result in radiographic fusion rates similar to metal constructs. Low rates of hardware failure or need for revision surgery were found. Preliminarily results of low rates of adjacent segment surgery are comparable with previously published metal construct rates. Longer follow up is needed to confirm these findings and to investigate whether semirigid constructs truly offer some protection from adjacent segment disease when compared to all metal constructs.

Acknowledgments
The authors thank Shirley McCartney, PhD, for editorial assistance.

Surgical treatment of degenerative lumbar spine disease has been rising steadily in the United States, and an increasing fraction of surgery involves lumbar fusion.^1,2 Various techniques are used to accomplish a lumbar fusion, including noninstrumented fusion, anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (XLIF, OLIF), posterior pedicle screw fusion, posterior cortical screw fusion, posterior interbody fusion (TLIF, PLIF), and interspinous process fusion. Rigid, metallic fusion hardware provides high stability and fusion rates, but it likely leads to stress shielding and adjacent segment disease.³ There is interest in less rigid and dynamic stabilization techniques to reduce the risk of adjacent segment disease, such as polyetheretherketone (PEEK) rods, which have been available since 2007. However, literature regarding PEEK rod utility is sparse and of mixed outcomes.^3,4 Additional patient reported outcome (PRO) information would be useful to both surgeons and patients. Using institutional data, this review was designed to examine our experience with PEEK rod lumbar fusion and to document PROs.

Methods

The study was approved by the institutional review board at the US Department of Veterans Affairs (VA) Portland Health Care System (VAPHCS) in Oregon with a waiver of authorization. In this retrospective, single center study, data were queried from the senior author’s (DAR) case logs from VA Computerized Patient Record System (CPRS). Electronic medical records, imaging, and PROs of all consecutive patients undergoing lumbar fusion at 1 or 2 levels with PEEK rods for degenerative disease were retrospectively reviewed. Cases of trauma, malignancy, or infection were excluded. From March 2011 through October 2019, 108 patients underwent lumbar fusion with PEEK rods.

Surgeries were conducted on a Mizuho OSI Jackson Table via bilateral 3 to 4 cm Wiltse incisions using the Medtronic Quadrant retractor system. Medtronic O-Arm images were acquired and delivered to a Medtronic Stealth Station for navigation of the screws. Monopolar coagulation was not used. PEEK pedicle screws were placed and verified with a second O-Arm spin before placing lordotic PEEK rods in the screw heads. No attempt was made to reduce any spondylolisthesis, but distraction was used to open the foramina and indirectly decompress the canal. An interbody device was placed only in treatment of multiply recurrent disc protrusion. After decortication of the transverse processes and facets, intertransverse fusion constructs consisting of calcium hydroxyapatite soaked in autologous bone marrow blood and wrapped in 6-mg bone morphogenetic protein-soaked sponges were placed on the bone. If canal decompression was indicated, a Medtronic Metrx retractor tube was then placed through one of the incisions and decompression carried out. Wounds were closed with absorbable suture. No bracing was used postoperatively. Figure 1 shows a typical single level PEEK rod fusion construct.

Statistical Analysis

Pre- and postoperative pairwise t tests were completed for patients with a complete data, using SAS 9.2 statistical package. Data are presented as standard deviation (SD) of the mean.

Results

Following application of the inclusion/exclusion criteria, 108 patients had undergone lumbar fusion with PEEK rods. Mean (SD) patient age was 60.2 (10.3) years and 88 patients were male (Table 1). Most surgeries were at L5-S1 and L4-5. There were 97 single-level fusions and 11 bilevel fusions. Seventy-four procedures were for spondylolisthesis, 23 for foraminal stenosis, 5 for degenerative disc disease, 3 for coronal imbalance with foraminal stenosis, 2 for pseudarthrosis after surgery elsewhere, and 1 for multiple recurrent disc herniation (Table 2). Twenty-five patients (23.1%) were current tobacco users and 28 (25.9%) were former smokers, 26 (24.1%) had diabetes mellitus (DM), 16 (14.8%) had low bone density by dual energy X-ray absorptiometry (DEXA) imaging, 35 (32.4%) had depression, and 7 (6.5%) were taking an immunosuppressive agent (chronic steroids, biological response modifiers, or methotrexate). Mean body mass index was 30.1.

Surgical Procedure

Of the 108 patients, the first 18 underwent a procedure with fluoroscopic guidance and the Medtronic FluoroNav and Stealth Systems. The next 90 patients underwent a procedure with O-Arm intraoperative CT scanning and Stealth frameless stereotactic navigation. The mean (SD) length of stay was 1.7 (1.3) days. There were no wound infections and no new neurologic deficits. Mean (SD) follow up time was 30.3 (21.8) months.

Imaging

Final imaging was by radiograph in 73 patients, CT in 31, and magnetic resonance imaging (MRI) in 3 (1 patient had no imaging). Sixty-seven patients (62.0%) had a bilateral arthrodesis, and 15 (13.9%) had at least a unilateral arthrodesis. MRI was not used to assess arthrodesis. Eight patients (7.4%) had no definite arthrodesis. Seventeen patients had inadequate or early imaging from which a fusion determination could not be made. Of 81 patients with > 11 months of follow up, 58 (71.6%) had a bilateral arthrodesis, 12 (14.8%) had a unilateral arthrodesis, 8 (9.9%) had no arthrodesis, and 3 (3.7%) were indeterminate.

No patient had any revision fusion surgery at the index level during follow up. Two patients had adjacent level fusions at 27 and 60 months after the index procedure. One patient had a laminectomy at an adjacent segment at 18 months postfusion, and 1 had a foraminotomy at an adjacent segment 89 months post fusion (Figure 3). Overall, there were 4 (3.7%) adjacent segment surgeries at a mean of 48.5 months after surgery. One patient had a sacro-iliac joint fusion below an L5-S1 fusion 17 months prior for persisting pain after the fusion procedure.

Patient Reported Outcomes

Preoperative SF-36 PF and ODI scores were available for 81 patients (Table 3). Postoperative SF-36 PF scores were obtained at 3 months for 65 of these patients, and at 1 year for 63 patients. Postoperative ODI scores were obtained at 3 months for 65 patients, and at 1 year for 55 patients. Among the 65 patients with completed SF-36 scores at 3 months, a mean increase of 22.4 (95% CI, 17-27; P < .001) was noted, and for the 63 patients at 1 year a mean increase of 30.3 (95% CI, 25-35; P < .001) was noted. Among the 65 patients with completed ODI scores at 3 months, a mean decrease of 6.8 (95% CI, 4.9-8.6; P < .001) was noted, and for the 55 patients with completed ODI scores at 1 year a mean decrease of 10.3 (n = 55; 95% CI, 8.4-12.2; P < .001) was noted.

Cost

We compared the hardware cost of a single level construct consisting of 4 pedicle screws, 4 locking caps, and 2 rods using a PEEK system with that of 2 other titanium construct systems. At VAPHCS, the PEEK system cost was about 71% of the cost of 2 other titanium construct systems and 62% of the cost when compared with Medtronic titanium rods.

Discussion

PEEK is useful for spine and cranial implants. It is inert and fully biocompatible with a modulus of elasticity between that of cortical and cancellous bone, and much lower than that of titanium, and is therefore considered to be semirigid.^3,4,6 PEEK rods are intermediate in stiffness between titanium rods (110 Gigapascals) and dynamic devices such as the Zimmer Biomet DYNESYS dynamic stabilization system or the Premia Spine TOPS system.³ Carbon fiber rods and carbon fiber reinforced PEEK implants are other semirigid rod alternatives.^7,8 PEEK rods for posterior lumbar fusion surgery were introduced in 2007. Li and colleagues provide a thorough review of the biomechanical properties of PEEK rods.³

PEEK is thought to have several advantages when compared with titanium. These advantages include more physiologic load sharing and reduction in stress shielding, improved durability, reduced risk of failure in osteoporotic bone, less wear debris, no change in bone forming environment, and imaging radiolucency.^4,9 Spinal PEEK cages have been reported to allow more uniform radiation dose distribution compared with metal constructs, an advantage that also may pertain to PEEK rods.¹⁰ Disadvantages of PEEK rods include an inability to detect rod breakage easily, lack of data on the use in more than minimally unstable clinical situations, and greater expense, although this was not the authors’ observation.^3,4,11

Importantly, it has been reported that PEEK rods permit a greater range of motion in all planes when compared with titanium rods.⁹ Polyetheretherketone rods unload the bone screw interface and increased the anterior column load to a more physiologic 75% when compared with titanium rods.^6,9 However, in another biomechanical study that compared titanium rods, PEEK rods, and a dynamic stabilization device, it was reported that anterior load sharing was 55%, 59%, and 75%, respectively.¹² This indicated that PEEK rods are closer to metal rods than truly dynamic devices for anterior load sharing. The endurance limit of a PEEK rod construct was similar to that of clinically useful metal systems.⁹ PEEK rods resulted in no increase in postfatigue motion compared with titanium rods in a biomechanical model.¹³ Intradiscal pressures at PEEK instrumented segments were similar to uninstrumented segments and greater than those with titanium rod constructs.¹⁴ Intradiscal pressures at adjacent segments were highest with dynamic devices, intermediate with semirigid rods, and lowest with rigid constructs; however, stress values at adjacent segments were lower in PEEK than titanium constructs in any direction of motion.^15,16

Fusion Rates

The use of PEEK rods in lumbar fusion has been reported previously.^3,4,17,18 However, these studies featured small sample sizes, short follow up times, and contradictory results.⁴ Of 8 outcome reports found in a systematic review, 2 studies reported on procedures designed to create nonfusion outcomes (a third similar trial from 2013 was not included in the systematic review), and 1 study reported only on the condition of PEEK rods removed at subsequent surgery.^3,19-21 Reported fusion rates varied from 86 to 100%.

In 42 patients with PEEK rod fusions who were followed for a mean of 31.4 months, 5 patients required adjacent segment surgery and 3 patients were treated for interbody cage migration and nonunion.¹⁷ Radiographic fusion rate was 86%. These authors concluded that PEEK rod fusion results were similar to those of other constructs, but not better, or perhaps worse than, metal rods.

Other studies have reported better results with PEEK.^{11,18,19,22-24} Highsmith and colleagues reported on 3 successful example cases of the use of PEEK rods.¹¹ De Iure and colleagues reported on 30 cases up to 5 levels (mean, 2.9) using autograft bone, with a mean follow up of 18 months.²³ Results were reported as satisfactory. Three patients had radiographic nonunions, 1 of which required revision for asymptomatic screw loosening at the cranial end of the construct. Qi and colleagues, reported on 20 patients with PEEK rods compared to 21 patients with titanium alloy rods.²⁴ Both groups had similar clinical outcomes, structural parameters, and 100% fusion rates. Athanasakopoulos and colleagues reported on 52 patients with up to 3 level fusions followed for a mean of 3 years.²² There were significant improvements in PROs: at 1 year 96% had radiographic union. Two patients had screw breakage, 1 of whom required revision to a metal rod construct. Colangeli and colleagues reported on 12 patients treated with PEEK rods compared with 12 who were treated with a dynamic system.¹⁸ They reported significant improvements, no complications, and 100% fusion at 6 months. Huang and colleagues reported on 38 patients intended to undergo a nonfusion procedure with 2 years of follow up.¹⁹ They reported good outcomes and 1 case of screw loosening. As no fusion was intended, no fusion outcomes were reported. All these studies suggested that longer follow up and more patients would be needed to assess the role of PEEK rods in lumbar fusion.³

Our results show a radiographic fusion rate of 86.4% and a radiographic nonunion rate of 9.9% in patients followed for at least 12 months. There was no clinical need for revision fusion at the index level. In our retrospective review, patients had high levels of smoking, DM, depression, immunosuppression, and obesity, which may negatively influence radiographic fusion rates when compared with other studies with 100% reported fusion rates. There was no instance of construct breakage or screw breakout, indicating that PEEK rods may allow enough flexibility to avoid construct failure under stress as in a fall.

Patient Reported Outcomes

Recent large studies were reviewed to assess the pre- and postoperative patient PROs reported in comparison with our study population (Table 4). In the Swedish Spine Registry analysis of 765 patients with 3 different types of lumbar fusion, the mean preoperative ODI score was 37 and mean SF-36 physical component score (PCS) was 35 for the most similar approach (posterolateral fusion with instrumentation).²⁵ At 1 year postoperation, the mean ODI was 26 and mean SF-36 PCS was 43. In the Spine Patient Outcomes Research Trial (SPORT) spondylolisthesis trial of 3 fusion types, the mean preoperative ODI was 41.2 and mean SF-36 PF score was 31.2 for the most similar approach (posterolateral instrumented fusion with pedicle screws).²⁶ Postoperative ODI scores at 1 year decreased by a mean 20.9 points and mean SF-36 PF scores increased by 29.9.

We report a mean preoperative SF-36 PF score of 28.9, which is lower than the SPORT study score for posterolateral fusion with instrumentation and the Swedish Study score for posterolateral instrumented fusion with pedicle screws. Similarly, our mean ODI score of 24.8 was better than the scores reported in the Swedish and SPORT studies. Our mean SF-36 PF score at 1 year postoperation was 59.3, compared with 58.5 for the SPORT study group and 46.0 in the Swedish study group. Mean ODI score at 1 year postoperatively was 14.5, which is better than the scores reported in the Swedish and SPORT studies.

Minimally clinically important difference (MCID) is a parameter used to gauge the efficacy of spine surgery. The utility of the MCID based upon PROs has been questioned in lumbar fusion surgery, as it has been thought to measure if the patient is “feeling” rather than “doing” better, the latter of which can be better measured by functional performance measures and objective, external socioeconomic anchors such as return to work and health care costs.²⁷ Nevertheless, validated PROs are reported widely in the spine surgery literature. The MCID in the SF-36 is not well established and can depend upon whether the scores are at the extremes or more in the central range and whether there is large variability in the scores.²⁸ Rheumatoid arthritis was estimated to be 7.1 points on the PF scale and 7.2 on the physical component summary (PCS).²⁹ For total knee replacement, it has been estimated to be 10 points on the SF-36 PCS.³⁰ Lumbar surgery was estimated to be 4.9 points for the SF-36 PCS and 12.8 points for the ODI.³¹ And the SPORT trial it has been estimated that a 30% change in the possible gain (or loss) may be an appropriate criterion.²⁸

With a preoperative mean SF-36 PF of 28.9, a 30% improvement in the available range (70.1) would be 21 points, making our data mean improvement of 30 points above the MCID. With a mean preoperative ODI of 24.6, a 30% improvement in the available range (25.4) would be 7.6 points, making our data mean improvement of 10.3 points better than the MCID. Therefore, our outcome results are comparable with other lumbar fusion outcome studies in terms of degree of disability prior to surgery and amount of improvement from surgery.

Adjacent Segment Disease

The precise factors resulting in adjacent segment disease are not fully defined.^3,32 In reviews of lumbar adjacent segment disease, reported rates ranged from 2.5% at 1 year up to 80 to 100% at 10 years, with lower rates with noninstrumented fusions.^4,32-34 Annual incidence of symptomatic adjacent segment disease following lumbar fusion ranges from 0.6 to 3.9% per year.^32,35,36 Mismatch between lumbar lordosis and pelvic incidence after fusion is thought to lead to higher rates of adjacent segment disease, as can a laminectomy at an adjacent segment.^32,36 Percutaneous fusion techniques or use of the Wiltse approach may lower the risk of adjacent segment disease due to avoidance of facet capsule disruption.^37,38

Dynamic stabilization techniques do not appear be clearly protective against adjacent segment disease, although biomechanical models suggest that they may do so.^33,39,40 A review by Wang and colleagues pooled studies to assess the risk of lumbar adjacent segment disease in spinal fusion to compare to disc arthroplasty and concluded that fusion carried a higher risk of adjacent segment disease.⁴¹ Definitive data on other types of motion preservation devices is lacking.³We show 3 adjacent segment fusions and 1 laminectomy have been needed in 108 patients and at a mean of 46 months after the index procedure and over 2.5 years of mean overall follow up. This is a low adjacent segment surgery rate compared to the historical data cited above, and may suggest some advantage for PEEK rods over more rigid constructs.

Strengths and Limitations

Strengths of this study include larger numbers than prior series of PEEK rod use and use in a population with high comorbidities linked to poor results without reduction in good outcomes. PEEK rods as used at the VAPHCS do not result in higher instrumentation costs than all metal constructs.

Study limitations include the retrospective nature with loss of follow up on some patients and incomplete radiographic and PROs in some patients. The use of 100% stereotactic guidance, the avoidance of interbody devices, and the off-label use of bone morphogenetic protein as part of the fusion construct introduce additional variables that may influence comparison to other studies. To avoid unnecessary radiation exposure, flexion extension films or CT scans were not routinely obtained if patients were doing well.⁴² Additionally, the degree of motion on dynamic views that would differentiate pseudarthrosis from arthrodesis has not been defined.⁵

Conclusions

The results presented show that lumbar fusion with PEEK rods can be undertaken with short hospitalization times and low complication rates, produce satisfactory clinical improvements, and result in radiographic fusion rates similar to metal constructs. Low rates of hardware failure or need for revision surgery were found. Preliminarily results of low rates of adjacent segment surgery are comparable with previously published metal construct rates. Longer follow up is needed to confirm these findings and to investigate whether semirigid constructs truly offer some protection from adjacent segment disease when compared to all metal constructs.

Acknowledgments
The authors thank Shirley McCartney, PhD, for editorial assistance.