Transient epileptic amnesia: Rare, treatable, and easy to miss

 

LOS ANGELES – Transient epileptic amnesia is a rare but a treatable memory condition that usually occurs in late life and can be mistaken for neurodegenerative disease among patients presenting to a neurology or memory clinic.

Transient epileptic amnesia (TEA) is thought to be a focal epilepsy whose major clinical feature is the presence of recurrent spells of anterograde or retrograde amnesia lasting under an hour. The spells tend to occur on waking from sleep.

©Thinkstock

Patients do not usually show prominent deficits in other cognitive domains, and the disorder can come with more chronic memory complaints between spells, with patients reporting accelerated forgetting over days to weeks of recently learned information, or patchy losses of remote autobiographical memory.

At the annual meeting of the American Academy of Neurology, Vijay Ramanan, MD, PhD, of the Mayo Clinic in Rochester, Minn., presented a retrospective series of 31 TEA cases from a study attempting to characterize the disorder in more demographic, clinical, and neuroimaging detail than has been done in the literature to date.

The cases were seen over a 20-year period (1998-2017) at the Mayo Clinic. All had at least one EEG and at least one MRI result reviewed by a neuroradiologist. Half also underwent fluorodeoxyglucose (FDG)-positron emission tomography (PET). All cases were classed as TEA if they included recurrent amnesia and an epileptic trait (lip smacking, for example), recurrent amnesiac spells and memory complaints between spells, or memory complaints and an epileptic trait.

Of the 31 cases, two-thirds were male, and the mean age was 70. Neuropsychological testing found mild nonspecific abnormalities in 10 individuals and mild cognitive impairment in 2.

The investigators found 20 patients had abnormalities on EEG, usually in the temporal epileptogenic region. On MRI, abnormalities were found in only 6 patients.

 

FDG-PET, however, revealed focal abnormalities in 11 of the 16 cases that underwent scanning. “Most of them had focal areas of hypometabolism; none of those metabolic patterns fit those of known neurodegenerative disorders, and more rarely they were entirely normal,” Dr. Ramanan said during a presentation of his findings.

The results suggest that FDG-PET “may be a more useful tool than EEG” in distinguishing TEA from other disorders, he said. “I think the fascinating question going forward is whether TEA has an underlying biomarker and if there’s a neuroimaging biomarker for this. From these data, I think FDG-PET could be a very promising avenue for that,” he said.

In most of these cases where there was an abnormality detected on EEG, he noted that the patient “had multiple or prolonged EEGs, so it’s not always an easy thing to catch.”

Dr. Ramanan stressed that it’s important for clinicians “to have your antennae up for this diagnosis, particularly as these patients will come in with chronic memory trouble, because this is something we can fix.” In his study, all of the 22 individuals followed up after treatment with antiepileptic drugs, most commonly lamotrigine or levetiracetam, improved on follow-up.

Dr. Ramanan and his colleagues disclosed no conflicts of interest related to their findings.

SOURCE: Ramanan V et al. Neurology. 2018 Apr 90(15 Suppl.):P3.035.

 

LOS ANGELES – Transient epileptic amnesia is a rare but a treatable memory condition that usually occurs in late life and can be mistaken for neurodegenerative disease among patients presenting to a neurology or memory clinic.

Transient epileptic amnesia (TEA) is thought to be a focal epilepsy whose major clinical feature is the presence of recurrent spells of anterograde or retrograde amnesia lasting under an hour. The spells tend to occur on waking from sleep.

©Thinkstock

Patients do not usually show prominent deficits in other cognitive domains, and the disorder can come with more chronic memory complaints between spells, with patients reporting accelerated forgetting over days to weeks of recently learned information, or patchy losses of remote autobiographical memory.

At the annual meeting of the American Academy of Neurology, Vijay Ramanan, MD, PhD, of the Mayo Clinic in Rochester, Minn., presented a retrospective series of 31 TEA cases from a study attempting to characterize the disorder in more demographic, clinical, and neuroimaging detail than has been done in the literature to date.

The cases were seen over a 20-year period (1998-2017) at the Mayo Clinic. All had at least one EEG and at least one MRI result reviewed by a neuroradiologist. Half also underwent fluorodeoxyglucose (FDG)-positron emission tomography (PET). All cases were classed as TEA if they included recurrent amnesia and an epileptic trait (lip smacking, for example), recurrent amnesiac spells and memory complaints between spells, or memory complaints and an epileptic trait.

Of the 31 cases, two-thirds were male, and the mean age was 70. Neuropsychological testing found mild nonspecific abnormalities in 10 individuals and mild cognitive impairment in 2.

The investigators found 20 patients had abnormalities on EEG, usually in the temporal epileptogenic region. On MRI, abnormalities were found in only 6 patients.

 

FDG-PET, however, revealed focal abnormalities in 11 of the 16 cases that underwent scanning. “Most of them had focal areas of hypometabolism; none of those metabolic patterns fit those of known neurodegenerative disorders, and more rarely they were entirely normal,” Dr. Ramanan said during a presentation of his findings.

The results suggest that FDG-PET “may be a more useful tool than EEG” in distinguishing TEA from other disorders, he said. “I think the fascinating question going forward is whether TEA has an underlying biomarker and if there’s a neuroimaging biomarker for this. From these data, I think FDG-PET could be a very promising avenue for that,” he said.

In most of these cases where there was an abnormality detected on EEG, he noted that the patient “had multiple or prolonged EEGs, so it’s not always an easy thing to catch.”

Dr. Ramanan stressed that it’s important for clinicians “to have your antennae up for this diagnosis, particularly as these patients will come in with chronic memory trouble, because this is something we can fix.” In his study, all of the 22 individuals followed up after treatment with antiepileptic drugs, most commonly lamotrigine or levetiracetam, improved on follow-up.

Dr. Ramanan and his colleagues disclosed no conflicts of interest related to their findings.

SOURCE: Ramanan V et al. Neurology. 2018 Apr 90(15 Suppl.):P3.035.

 

LOS ANGELES – Transient epileptic amnesia is a rare but a treatable memory condition that usually occurs in late life and can be mistaken for neurodegenerative disease among patients presenting to a neurology or memory clinic.

Transient epileptic amnesia (TEA) is thought to be a focal epilepsy whose major clinical feature is the presence of recurrent spells of anterograde or retrograde amnesia lasting under an hour. The spells tend to occur on waking from sleep.

©Thinkstock

Patients do not usually show prominent deficits in other cognitive domains, and the disorder can come with more chronic memory complaints between spells, with patients reporting accelerated forgetting over days to weeks of recently learned information, or patchy losses of remote autobiographical memory.

At the annual meeting of the American Academy of Neurology, Vijay Ramanan, MD, PhD, of the Mayo Clinic in Rochester, Minn., presented a retrospective series of 31 TEA cases from a study attempting to characterize the disorder in more demographic, clinical, and neuroimaging detail than has been done in the literature to date.

The cases were seen over a 20-year period (1998-2017) at the Mayo Clinic. All had at least one EEG and at least one MRI result reviewed by a neuroradiologist. Half also underwent fluorodeoxyglucose (FDG)-positron emission tomography (PET). All cases were classed as TEA if they included recurrent amnesia and an epileptic trait (lip smacking, for example), recurrent amnesiac spells and memory complaints between spells, or memory complaints and an epileptic trait.

Of the 31 cases, two-thirds were male, and the mean age was 70. Neuropsychological testing found mild nonspecific abnormalities in 10 individuals and mild cognitive impairment in 2.

The investigators found 20 patients had abnormalities on EEG, usually in the temporal epileptogenic region. On MRI, abnormalities were found in only 6 patients.

 

FDG-PET, however, revealed focal abnormalities in 11 of the 16 cases that underwent scanning. “Most of them had focal areas of hypometabolism; none of those metabolic patterns fit those of known neurodegenerative disorders, and more rarely they were entirely normal,” Dr. Ramanan said during a presentation of his findings.

The results suggest that FDG-PET “may be a more useful tool than EEG” in distinguishing TEA from other disorders, he said. “I think the fascinating question going forward is whether TEA has an underlying biomarker and if there’s a neuroimaging biomarker for this. From these data, I think FDG-PET could be a very promising avenue for that,” he said.

In most of these cases where there was an abnormality detected on EEG, he noted that the patient “had multiple or prolonged EEGs, so it’s not always an easy thing to catch.”

Dr. Ramanan stressed that it’s important for clinicians “to have your antennae up for this diagnosis, particularly as these patients will come in with chronic memory trouble, because this is something we can fix.” In his study, all of the 22 individuals followed up after treatment with antiepileptic drugs, most commonly lamotrigine or levetiracetam, improved on follow-up.

Dr. Ramanan and his colleagues disclosed no conflicts of interest related to their findings.

SOURCE: Ramanan V et al. Neurology. 2018 Apr 90(15 Suppl.):P3.035.