Abstracts

Rationale: Focal Cortical Dysplasia (FCD) is the most frequent surgical remediable etiology in children. Two major categories are distinguished: FCD I and II. Some interictal and ictal electrophysiologic patterns have been described in different FCD. Nevertheless, the association between SEEG activity and histologic type, remains unclear especially for FCD I and non-dysplastic lesions as gliosis or normal cortex. The aim of the study is to compare interictal and ictal activity from Stereo-EEG recordings, in patients with FCD type I, II and gliosis, in order to investigate possible electrical biomarkers. Methods: We reviewed all clinical, stereo-EEG and neuroimaging features of the 22, consecutively recruited patients from 2011 to 2017, with Cortical Dysplasia (FCD) or non-dysplastic lesion. FCD I was identified in 8, FCD type II in 10 and only gliosis in 4 patients. Interictal abnormalities were sub-grouped as focal, regional or extended and as continuous with a frequency from 1 to 10Hz or single random with a frequency < 1Hz. Ictal patterns were classified into three categories based upon morphology: burst suppression, spiking activity and fast activity. Results: Interictal patterns were analyzed in 22/22 patients: 7/8 patients with FCD I had single random abnormalities (87.5%) while 9/10 with FCD II had continuous abnormalities (90%) and 4/4 with gliosis had single random abnormalities (100%).  Ictal patterns were analyzed in 20/22 patients: 5/6 patients with FCD I have only fast activity (83.3%) while in 7/10 patients with FCD II there was a preceding burst suppression pattern (70%) and in 4/4 patients with gliosis again only fast activity (100%). Conclusions: Our data confirm the typical interictal and ictal pattern of FCD type II with repetitive interictal high frequency focal abnormalities and an ictal burst suppression pattern. We didn't find any difference between FCD I and non-dysplastic-tissue. Funding: No funding