Anterior corpus callosotomy in multistep invasive monitoring and surgery for atonic seizures

Identifying the epileptogenic zone (EZ) in patients with refractory nonlesional frontal lobe epilepsy is frequently challenging. Intracranial EEG (icEEG) recordings are often required to better delineate the EZ, but the presence of an extensive network of connections allowing rapid ictal spreadmay result in bilateral homologous regional ( or extremely diffuse) electrical ictal patterns. Here, we report a case where callosotomy performed after a first nonlateralizing icEEG study allowed for adequate identification of the EZ. The patient, an 18-year-old lefthanded woman with daily atonic spells, had synchronous interictal and ictal epileptic activity from both supplementary motor areas (SMAs) during icEEG. Anterior partial callosotomy localized the EZ to the right SMA, as seizures were no longer associated with mirror-image ictal activity over the left SMA. Right SMA resection led to seizure freedom(follow-up of 23 months). This case exemplifies howa partial callosotomy followed by further icEEG recordingsmay adequately localize the EZwhen initial icEEG recordings reveal bilateral synchronous focal or regional ictal activities. (C) 2013. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license.