Is inpatient ictal video-electroencephalographic monitoring mandatory in mesial temporal lobe epilepsy with unilateral hippocampal sclerosis? A prospective study.

Abstract

To compare surgical outcome in mesial temporal lobe epilepsy (MTLE) patients with unilateral hippocampal sclerosis (MTLE-HS) who had or did not have preoperative video-electroencephalographic monitoring (VEEG). A prospective study was undertaken with 166 consecutive pharmacoresistant unilateral MTLE-HS patients. All patients were investigated with detailed seizure semiology, serial routine outpatient EEG, magnetic resonance imaging, neuropsychological evaluation, and if necessary, other examinations. Postoperative follow-up ranged between 2 and 16years. Patients were divided into: (1) patients operated on based on routine outpatient EEG information, with >80% of EEGs with unilateral interictal epileptiform discharges (IEDs) ipsilateral to HS or ictal events (n=71); and (2) patients submitted to preoperative VEEG (n=95). To avoid the bias generated by ictal recordings, we performed a subanalysis of: (1) patients without preoperatively ictal recordings (n=80) and (2) patients with ictal recordings in VEEG or routine outpatient EEG (n=86). Groups were similar regarding gender, age at surgery, seizure onset, preoperative seizure frequency, and duration of follow-up. Overall, 136/166 (81.92%) were classified as Engel I seizure outcome, with no difference between groups; 76.84% and 88.73% of patients with and without VEEG, respectively, had Engel I postoperative seizure outcome (P=.77). The time lag until surgery was shorter in the group without VEEG (80 vs 38months; P=.01). Considering ictal recordings, 76.74% of patients with seizures recorded and 87.50% without ictal recordings had Engel I outcome (P=.11). We performed the first prospective study in a tertiary epilepsy center comparing surgical outcomes in unilateral MTLE-HS patients investigated preoperatively with and without VEEG. Based on the surgical outcome, VEEG is not imperative in patients with unilateral MTLE-HS who have compatible semiology and clearly ipsilateralized IEDs evaluated by a multidisciplinary and experienced epilepsy group.