Abstracts

Rationale: Previous studies have attempted to analyze the electro-clinical correlations in temporal lobe epilepsy. However, the boundaries of the so-called “temporal lobe seizures” semiology are imprecise. In fact, dense anatomo-functional interconnections between medial temporal and peri-sylvian regions are involved in temporal seizure spread so that distinction between temporal and perisylvian ictal semiology can be difficult to assess. A better understanding of ictal manifestations underlying network would help to improve presurgical localization. This study aims to analyze anatomo-electro-clinical correlations by using visual analysis of Stereoelectroencephalography (SEEG) in Temporal Peri-sylvian epilepsies.Methods: We reviewed the patients with temporal peri-sylvian epilepsies who had been explored with SEEG followed by resective epilepsy surgery at Cleveland Clinic between January 2010 to December 2014. Patients were classified into three subtypes according to the anatomic origin of the ictal patterns: Medial temporal (MT; amygdala, hippocampus, Rhinal cortex (ento + perirhinal), parahippocampal cortex), Temporal PeriSylvian (T-PS; MT +Superior temporal gyrus (STG), Opercular cortices, Insula), PeriSylvian (PS; STG, Opercular cortices, Insula) The patients who had no ictal recording during intracranial monitoring, no electrodes sampling in peri-sylvian regions and less than 6 months follow up were excluded.Results: A total of 120 SEEG-recorded seizures in 30 patients were analyzed. Patients were classified into three subtypes: Medial temporal (MT, n=13), Temporal PeriSylvian (T-PS, n=2) and PeriSylvian (PS, n=15). The MT subtype is characterized by an initial motionless, delayed loss of contact, delayed oroalimentary and gestural automatisms, delayed tonic and dystonic posturing. Electrical onset preceded clinical onset by a longer duration in MT subtype (mean, 19.6 seconds) than in PS subtype (mean, 9.8 seconds). The PS subtype is characterized by an initial somatosensory and/or auditory aura, an initial face grimacing, vocalization, autonomic manifestations and frequent secondary generalizations. The MT-PS subtype is characterized by an initial stereotyped axial movement like pure PS subtype and delayed oroalimentary and gestural automatisms like pure MT subtype.Conclusions: Differences in clinical semiology between seizures with temporal onset and seizures with peri-sylvian onset are demonstrated. A large part of clinical signs classically attributed to mesial temporal involvement are actually generated by spread to perisylvian areas, that explains why the distinction can be often difficult. The semiology assigned to perisylvian onset share similarities, with a shorter onset delay and more intense motor and autonomic manifestations.