Abstracts

Rationale: Resective surgery is considered a successful treatment option for refractory localization related epilepsy. Most studies have reported seizure outcomes of 2-5 years post-surgery and a few up to 10 years. Our aim was to assess post-surgical outcomes that exceeds 10 years of follow up,and correlate the outcomes to the pathology and the side of resection. Methods: After obtaining IRB approval, the Henry Ford Health System Corporate Data Store was used to identify patients who had surgical resection for localization related epilepsy from 1993 to 2011. Demographics, age at epilepsy onset and surgery, seizure frequency before surgery, pathology, and number of antiepileptic drugs (AEDs) before and after surgery was gathered from electronic medical records. Phone surveys were conducted by research assistants in 05/2012 to determine the patients' current seizure frequency. Surgical outcomes were based on Engel's classification (class I and II = favorable outcome). To assess the differences, chi-square tests, two sample t-tests and Wilcoxon two sample tests were used. Results: A total of 470 patients who had resective epilepsy surgery for localization related epilepsy were identified, 44 (9%) of which deceased since the time of their surgery. Of the remaining 426 patients, 202 (47%) were contacted. These patients had a mean age at the time of the survey of 46.6±13.3 years, mean age at epilepsy onset 16.3±14.1 years and mean age at epilepsy surgery 36.8±13.1 years. The mean delay between epilepsy onset and surgery was 20.8±13.8 years, and follow up was obtained at 10.0 ± 5.2 (24% patients had follow up of 15 years or longer). Mean number of AEDs before surgery were 2.1±0.9 and after surgery were 2.1±0.8 (p=0.073). Of the 202 patients surveyed, Engel's classification was available for 200. Fifty six patients (28%) were seizure free and 146 patients (73%) had a favorable outcome (Class I and II) (table 1). Resection was performed in 94 patients (47%) after scalp EEG monitoring (sEEG) (phase I) and 106 patients (53%) after extra-operative electrocorticography (eECoG) (phase II). Statistical significance was noted in favorable outcomes when surgery was performed after sEEG ( 83% vs 64%) and in temporal region (77% vs 46%). Favorable outcomes were not significantly different based on pathology, and number of AEDs before and after surgery. Most importantly, the favorable outcomes, as well as seizure freedom rates remained stable over the long-term follow-up period after surgery [42 patients: <5 years (76%, 40%), 59 patients: 5-10 years (63%, 20%), 50 patients:10-15 years (78%, 30%), and 49 patients: >15 years (78%, 24%)]. Conclusions: Our study shows that a significant number of patients achieve favorable seizure outcomes(73%) or seizure freedom (28%) after resective epilepsy surgery, and demonstrates that the seizure outcomes remain stable over more than 15 years post surgery, irrespective of the pathology or the side of resection. Additional assessment of psychosocial outcomes are necessary to better help establish overall post-surgical outcomes after resective surgery for epilepsy.