Which Factors Predict Seizure Recurrence After Epilepsy Surgery?

SAN DIEGO—Resective surgery is a successful treatment for many patients with intractable epilepsy, but the risk factors for seizure recurrence have been unclear. A study presented at the 65th Annual Meeting of the American Academy of Neurology suggests that extratemporal seizure foci may predict unfavorable outcome at one year after surgery. Resection outside the site of ictal onset and the presence of widespread MRI lesions also may predict unfavorable outcomes, said Hai Chen, MD, PhD.

A Retrospective Review of Resection Outcomes
Dr. Chen, a resident in the Department of Neurology and Neurotherapeutics at the University of Texas Southwestern Medical Center in Dallas, and colleagues retrospectively reviewed 54 patients who had had epilepsy surgery between 2009 and 2012. Patients had at least six months of follow-up, and subjects with malignant tumors were excluded.

The investigators determined participants’ demographic data, clinical characteristics, imaging results, video-EEG monitoring results, and outcome by chart review. Dr. Chen’s group used univariate analysis to identify the predictors of outcome and survival analysis to investigate postoperative seizure recurrence.

Thirty patients were male, and the overall mean age was 38. Approximately 74% of patients had a history of generalized tonic-clonic seizures, and participants had had epilepsy for an average of 15 years.

Forty patients had temporal resection, and 14 had extratemporal resection. Resection was concordant with EEG ictal onset for 81% of the subjects, and 83% of patients had an abnormal MRI. Mean follow-up was 21 months.

Extratemporal Resection Predicted Unfavorable Outcome
Forty-three (80%) patients had an Engel class I outcome at the final follow-up visit. Of these individuals, 35 had had temporal resection and eight had had extratemporal resection. The remaining 11 patients had an Engel class II to IV outcome. Of these individuals, six had had extratemporal resection.

Extratemporal resection predicted an unfavorable outcome at one year, and discordance between EEG ictal onset site and resection site predicted an unfavorable outcome at two years. Widespread MRI lesions tended to predict unfavorable outcomes, but the results were not statistically significant. Outcome was not associated with age, gender, history of generalized seizures, epilepsy duration, preoperative seizure frequency, or lesion pathology.

Seizure recurrence was less frequent among patients who had had a temporal resection, compared with patients who had had an extratemporal resection. At one year, the risk of seizure recurrence stabilized for patients who had had temporal resections but kept increasing for patients who had had extratemporal resections.

“Favorable outcome at one year supports continued future good outcome after temporal resections,” said Dr. Chen. “Presumed reasons for unfavorable outcome include inadequate seizure focus localization and incomplete resection.”

—Erik Greb
Senior Associate Editor

Suggested Reading
Cleary RA, Thompson PJ, Fox Z, Foong J. Predictors of psychiatric and seizure outcome following temporal lobe epilepsy surgery. Epilepsia. 2012;53(10):1705-1712.

Najm I, Jehi L, Palmini A, et al. Temporal patterns and mechanisms of epilepsy surgery failure. Epilepsia. 2013;54(5):772-782.

SAN DIEGO—Resective surgery is a successful treatment for many patients with intractable epilepsy, but the risk factors for seizure recurrence have been unclear. A study presented at the 65th Annual Meeting of the American Academy of Neurology suggests that extratemporal seizure foci may predict unfavorable outcome at one year after surgery. Resection outside the site of ictal onset and the presence of widespread MRI lesions also may predict unfavorable outcomes, said Hai Chen, MD, PhD.

A Retrospective Review of Resection Outcomes
Dr. Chen, a resident in the Department of Neurology and Neurotherapeutics at the University of Texas Southwestern Medical Center in Dallas, and colleagues retrospectively reviewed 54 patients who had had epilepsy surgery between 2009 and 2012. Patients had at least six months of follow-up, and subjects with malignant tumors were excluded.

The investigators determined participants’ demographic data, clinical characteristics, imaging results, video-EEG monitoring results, and outcome by chart review. Dr. Chen’s group used univariate analysis to identify the predictors of outcome and survival analysis to investigate postoperative seizure recurrence.

Thirty patients were male, and the overall mean age was 38. Approximately 74% of patients had a history of generalized tonic-clonic seizures, and participants had had epilepsy for an average of 15 years.

Forty patients had temporal resection, and 14 had extratemporal resection. Resection was concordant with EEG ictal onset for 81% of the subjects, and 83% of patients had an abnormal MRI. Mean follow-up was 21 months.

Extratemporal Resection Predicted Unfavorable Outcome
Forty-three (80%) patients had an Engel class I outcome at the final follow-up visit. Of these individuals, 35 had had temporal resection and eight had had extratemporal resection. The remaining 11 patients had an Engel class II to IV outcome. Of these individuals, six had had extratemporal resection.

Extratemporal resection predicted an unfavorable outcome at one year, and discordance between EEG ictal onset site and resection site predicted an unfavorable outcome at two years. Widespread MRI lesions tended to predict unfavorable outcomes, but the results were not statistically significant. Outcome was not associated with age, gender, history of generalized seizures, epilepsy duration, preoperative seizure frequency, or lesion pathology.

Seizure recurrence was less frequent among patients who had had a temporal resection, compared with patients who had had an extratemporal resection. At one year, the risk of seizure recurrence stabilized for patients who had had temporal resections but kept increasing for patients who had had extratemporal resections.

“Favorable outcome at one year supports continued future good outcome after temporal resections,” said Dr. Chen. “Presumed reasons for unfavorable outcome include inadequate seizure focus localization and incomplete resection.”

—Erik Greb
Senior Associate Editor

Suggested Reading
Cleary RA, Thompson PJ, Fox Z, Foong J. Predictors of psychiatric and seizure outcome following temporal lobe epilepsy surgery. Epilepsia. 2012;53(10):1705-1712.

Najm I, Jehi L, Palmini A, et al. Temporal patterns and mechanisms of epilepsy surgery failure. Epilepsia. 2013;54(5):772-782.

SAN DIEGO—Resective surgery is a successful treatment for many patients with intractable epilepsy, but the risk factors for seizure recurrence have been unclear. A study presented at the 65th Annual Meeting of the American Academy of Neurology suggests that extratemporal seizure foci may predict unfavorable outcome at one year after surgery. Resection outside the site of ictal onset and the presence of widespread MRI lesions also may predict unfavorable outcomes, said Hai Chen, MD, PhD.

A Retrospective Review of Resection Outcomes
Dr. Chen, a resident in the Department of Neurology and Neurotherapeutics at the University of Texas Southwestern Medical Center in Dallas, and colleagues retrospectively reviewed 54 patients who had had epilepsy surgery between 2009 and 2012. Patients had at least six months of follow-up, and subjects with malignant tumors were excluded.

The investigators determined participants’ demographic data, clinical characteristics, imaging results, video-EEG monitoring results, and outcome by chart review. Dr. Chen’s group used univariate analysis to identify the predictors of outcome and survival analysis to investigate postoperative seizure recurrence.

Thirty patients were male, and the overall mean age was 38. Approximately 74% of patients had a history of generalized tonic-clonic seizures, and participants had had epilepsy for an average of 15 years.

Forty patients had temporal resection, and 14 had extratemporal resection. Resection was concordant with EEG ictal onset for 81% of the subjects, and 83% of patients had an abnormal MRI. Mean follow-up was 21 months.

Extratemporal Resection Predicted Unfavorable Outcome
Forty-three (80%) patients had an Engel class I outcome at the final follow-up visit. Of these individuals, 35 had had temporal resection and eight had had extratemporal resection. The remaining 11 patients had an Engel class II to IV outcome. Of these individuals, six had had extratemporal resection.

Extratemporal resection predicted an unfavorable outcome at one year, and discordance between EEG ictal onset site and resection site predicted an unfavorable outcome at two years. Widespread MRI lesions tended to predict unfavorable outcomes, but the results were not statistically significant. Outcome was not associated with age, gender, history of generalized seizures, epilepsy duration, preoperative seizure frequency, or lesion pathology.

Seizure recurrence was less frequent among patients who had had a temporal resection, compared with patients who had had an extratemporal resection. At one year, the risk of seizure recurrence stabilized for patients who had had temporal resections but kept increasing for patients who had had extratemporal resections.

“Favorable outcome at one year supports continued future good outcome after temporal resections,” said Dr. Chen. “Presumed reasons for unfavorable outcome include inadequate seizure focus localization and incomplete resection.”

—Erik Greb
Senior Associate Editor

Suggested Reading
Cleary RA, Thompson PJ, Fox Z, Foong J. Predictors of psychiatric and seizure outcome following temporal lobe epilepsy surgery. Epilepsia. 2012;53(10):1705-1712.

Najm I, Jehi L, Palmini A, et al. Temporal patterns and mechanisms of epilepsy surgery failure. Epilepsia. 2013;54(5):772-782.