Abstracts

Rationale: Resective epilepsy surgery is an accepted treatment for many patients with medically refractory epilepsy. We present here the clinical data and outcome of the contiguous patients operated between 1978 to 2007 for medically refractory epilepsy at the University of Western Ontario Epilepsy Programme, London Health Sciences Centre, Canada, a tertiary referral center for medically refractory seizures. Methods: Information about all patients (more than 2500) operated during that period of time was systematically entered into a database. Information obtained consisted of demographics, semiology of seizures, outpatient electroencephalography (EEG), video-EEG (VEEG), invasive monitoring results, neuropsychological and MRI data. Results: We only had complete information in 1025 patients (525 females). Mean age of seizure onset was 15.9 (+/-12.7 years) and the mean age at evaluation was 29.9 (+ 12.9 years). Interictal epileptiform discharges were noted in all but 35 patients. Ictal onset (VEEG) was unilateral temporal in 569 patients (right side: 275), frontal in 109 (right 62), parietal in 9 (right 5), occipital in 15 (right 7), bi-temporal in 60, regional (involving two contiguous lobes) in 179, hemispheric in 38, multifocal in 15 and generalized in 31. Invasive monitoring with subdural lines or depth electrodes was performed in 412 patients. MRI was abnormal in 747 patients. Neuropsychological evaluation identified concordant abnormalities in only a portion of patients [211(temporal); 53(extratemporal)]. Amytal test was performed in 275 patients for language lateralization and memory assesment. The commonest resective procedure performed was temporal lobectomy (614 patients) followed by frontal (136), occipital (26) and parietal (18) resections. Combined fronto-temporal resections were performed in 96 patients and 49 patients had other multilobar resections. Functional hemispherectomy was performed in 15 patients, corpus callosotomy 51 and multiple subpial transaction in 13. Pathology was available in 958 patients and identified mesial temporal sclerosis in 197, malformations of cortical development and tumors in 360, dual pathology in 21, nonspecific in 352 and normal in 48. Seizure freedom in temporal resections was 64.3% at one year, 61.6% at 2 years and 64.5% at 2 years. Extratemporal resections yielded seizure freedom rates of 41.1% at one year, 40.6% at 2 years and 40.4% at 3 years. Conclusions: This study indicates that temporal lobe epilepsy surgery remains the common surgical intervention in a tertiary referral center.