Abstracts

Rationale: Localization of epileptogenic area of frontal lobe and preservation of the functional area are critical points for frontal lobe epilepsy (FLE), which are important factors for favorable postoperative outcome without or with fewer complications. Both of video-EEG (VEEG) and MEG alone can provide informative clues for localization of epileptogenic areas in FLE, but not for all the cases. This study aims to investigate combination use of MEG and VEEG in FLE. Methods: Thirty patients with pharmaco-resistant FLE who underwent epilepsy surgery were retrospectively enrolled. Video EEG was recorded using an IT-med system using 10/20 system. Regional localization of spikes in VEEG was defined as spikes discharged from adjacent electrodes and no further propagation to a large and/or contralateral area. Magnetoencephalography was recorded for the purpose of focus assessment. Magnetoencephalography spikes were detected for dipole localization of the epileptogenic cortex and the epileptogenic area was classified as mono- or multi-focal. Results: Regional spike discharges were identified in the interictal VEEG of 20 patients and in the ictal VEEG of 17 patients. Thirteen patients had regional spikes in both interictal and ictal VEEG. Mono-focal localization was identified in the MEG of 20 patients. Fourteen of these patients had regional spike discharges in VEEG. In the remaining six patients, sources localization was only identified by MEG and there were no regional spike discharges either interictal or ictal VEEG. In 53.3% patients (16/30), the combination of VEEG and MEG provided localization of epileptic activities, including 11 patients had Engel 1 outcome. Conclusions: In clinical practice, VEEG is the routine procedure in the presurgical evaluation of FLE. However, we found six cases in which VEEG failed to locate the epileptogenic area that was identified by MEG. We therefore propose that combining VEEG and MEG will optimize the noninvasive presurgical evaluation of epileptiform activities in FLE. [This study was supported by the Deutsche Forschungsgemeinschaft (DFG, STE-380/14-1) ].