Abstracts

Rationale: In Norway, all epilepsy surgery is centralized to the National Center for Epilepsy and the Department of Neurosurgery at Oslo University Hospital. The aim of this study was to evaluate seizure outcome according to the Engel classification two years after epilepsy surgery. Methods: From our epilepsy surgery registries we have retrospectively collected data from all patients who had undergone resective epilepsy surgery in the period 2003-2012. The patients had been followed according to a standardized protocol of pre- and postoperative work-up and follow-up. Results: In this period, 276 surgical procedures on 227 patients (51% females) were performed. Mean age at the time of surgery was 30.1 yrs (x-y). 41 patients had two, and eight patients had three operations. 77 of the operations (34%) were in children (< 16 yrs). 149 patients (66%) had temporal and 63 patients (29%) had extra- temporal surgery. 16 patients (7%) had non-resective surgery. 197 (87%) of the patients were "MR positive". The most common epilepsy etiologies were: mesial temporal sclerosis (35%), tumor (15%), and cortical dysplasia (14%). At two year follow up 123 patients (54%) were classified as Engel class 1, 10 (4%) as class 2, 25 (11%) as class 3 and 64 (28%) class 4. Five patients were not possible to classify. 67% of the TLE patients were classified as Engel class 1, but only 20 (32%) of those with extra-temporal resections were Engel class 1. 74% of the patients with mesial temporal sclerosis were seizure free (Engel class 1). Conclusions: Despite increased effort and improved technology, extra-temporal resections continue to have a low success rate (32% Engel class 1) as compared to temporal resections (67% Engel class 1). This should be considered in the election of epilepsy surgery candidates and communicated to patients. Funding: None