P.097 After-discharges and presurgical cortical stimulation in stereo-encephalography in the study of drug-resistant epilepsy

Background: Cortical stimulation (CS) as a part of presurgical investigations in patients undergoing implantation depth electrodes (SEEG) is growing practice some Comprehensive Epilepsy Centers. After-discharges (AD) are useful to determine epileptogenic tissue within or outside the network. Classification afterdischarges was proposed by Blume using subdural recordings(1); its utility SEEG unknown. Methods: Single center, retrospective study that included with underwent CS Monitoring Unit. Demographic characteristics were explored and Blume’s AD classification used whether not changed surgical outcomes. Results: From January 2015 June 2021, total 177 implanted analyzed. 95 had 91 AD. Morphologies found were: Rhythmic waves 4 (0.04%), evolving into spikes in18 (19%), Polyspike bursts 14 (15%), Spike-waves 28 (30%), sequential 18 (19%). 12/14 (86%) Engel I outcome; class IV more likely have an evolution morphology frequency ADs 3 patients(75%). Conclusions: The most frequent seen spike-waves. duration may predict post-operative seizure