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Original Investigation
March 2017

Surgical Treatment of Nonlesional Neocortical EpilepsyLong-term Longitudinal Study

Author Affiliations
  • 1Department of Neurology, Konkuk University School of Medicine, Seoul, Korea
  • 2Department of Neurology, College of Medicine, Seoul National University Hospital, Seoul, Korea
  • 3Department of Neurology, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea
  • 4Department of Neurosurgery, College of Medicine, Seoul National University Hospital, Seoul, Korea
JAMA Neurol. 2017;74(3):324-331. doi:10.1001/jamaneurol.2016.4439
Key Points

Question  What are the long-term surgical outcomes and the possible prognostic factors in patients with nonlesional neocortical epilepsy?

Findings  In a long-term study that included 109 patients, nearly 60% of patients with nonlesional neocortical epilepsy achieved long-term freedom from seizure. Several factors, including localizing patterns in functional neuroimaging, concordant results in presurgical diagnostic evaluations, and the presence of aura, were associated favorable surgical outcome.

Meaning  Patients with nonlesional neocortical epilepsy can be good surgical candidates, and the presence of predictors of favorable surgical outcome would help select optimal candidates for surgical treatment.

Abstract

Importance  The proportion of surgery for nonlesional neocortical epilepsy has recently increased, with a decrease in surgery for mesial temporal lobe epilepsy. However, there are only a few studies regarding the long-term surgical outcome and the potential prognostic factors for patients with nonlesional neocortical epilepsy.

Objective  To evaluate the long-term surgical outcome and to identify possible prognostic factors in patients with nonlesional neocortical epilepsy.

Design, Setting, and Participants  In a surgical cohort from September 1995 to December 2005 at the Seoul National University Hospital, we included 109 consecutive patients without lesions identifiable by magnetic resonance imaging who underwent focal surgical resection for drug-resistant neocortical epilepsy. Follow-up information for at least 10 years was available for all but 1 patient.

Main Outcomes and Measures  Univariate and standard multiple logistic regression analyses were performed to identify the predictors of surgical outcomes, and a generalized estimation equation model was used for the longitudinal multiple logistic regression analysis of up to 21 years of follow-up.

Results  The patients consisted of 64 men and 45 women with ages at surgery ranging from 7 to 56 years (mean [SD], 27.1 [7.8] years). At 1 year after surgery, 59 of 109 patients (54.1%) achieved seizure freedom, and 64 of 108 patients (59.3%) achieved seizure freedom at the last follow-up. Only 11 of 108 patients (10.2%) experienced definite changes in postoperative seizure status. Localizing patterns in functional neuroimaging (strongest odds ratio [OR], 0.30 [95% CI, 0.14-0.66] for fluorodeoxyglucose–positron emission tomography; 0.37 [95% CI, 0.15-0.87] for ictal single-photon emission computed tomography), concordant results in presurgical diagnostic evaluations (OR, 3.15 [95% CI, 1.42-7.02]), the presence of aura (OR, 3.49 [95% CI, 1.54-7.92]), and complete resection of areas of ictal onset with frequent interictal spikes during the intracranial electroencephalographic study (OR, 0.37 [95% CI, 0.16-0.85]) were favorable surgical outcome predictors.

Conclusions and Relevance  Our study showed that nearly 60% of patients with nonlesional neocortical epilepsy achieved freedom from long-term seizure, and that changes in postoperative seizure status were rarely observed. Several predictors of favorable surgical outcomes were identified, which can help select optimal candidates for surgical treatment among patients with nonlesional neocortical epilepsy.

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