Abstracts

Rationale: The purpose of this study is to identify potential prognostic factors for favorable temporal resection outcomes in patients with medically refractory temporal lobe epilepsy (TLE) with bilateral features on pre-operative examination. Methods: We retrospectively reviewed 501 patients who underwent temporal resection for medically intractable TLE. 31 patients demonstrated bilateral features on surface EEG, and 16 of these were further examined with invasive EEG recordings. Bilateral features were defined as: bilateral independent temporal or bitemporal ictal onsets on surface or invasive EEG, or bitemporal interictal epileptiform abnormalities on surface EEG with bilateral radiographic mesiotemporal sclerosis. All patients underwent a pre-operative evaluation consisting of surface EEG, MRI, neuropsychological assessment, and Wada test. Surgical outcomes were classified according to reduction in seizure frequency: I (seizure freedom, 100% reduction), II (rare, almost seizure free, >= 75% reduction), III (worthwhile improvement, 50-74% reduction), IV (no worthwhile improvement, <50% reduction). Results: Of 31 patients, 14 (45%) improved to class I, and 9 (29%) improved to class II. Eight (26%) patients did not significantly improve (class III, class IV). Both lateralized mesiotemporal dysfunction on neuropsychological examination (p<0.05), and Wada dysfunction (p<0.05) concordant with side of resection were associated with a more favorable clinical outcome. Conclusions: Patients with bilateral features have been conventionally considered non-surgical candidates. Seizure reduction and freedom is possible in this population, and surgery can be considered a treatment option, particularly when neuropsychological evaluation shows lateralized mesiotemporal dysfunction, and Wada dysfunction is concordant with the side of resection.