Abstracts

Rationale: Gelastic seizures (GS) have has been mostly observed in association with hypothalamic hamartomas but they have also been described in cortical epileptogenic focus in basal temporal as well as mesial frontal regions. In this series of patients with gelastic epilepsy, we report here the localization of the epileptogenic foci as determined by multimodal investigation. Methods: We retrospectively identified patients with GS investigated in our epilepsy monitoring unit from 1974 until 2012. We retrospectively collected clinical, radiological and electrophysiological data for all identified cases through chart and video analyses. Only patients with GS observed during the long-term video EEG recordings and with at least one brain magnetic resonance imaging (MRI) study were included. Patients with GS associated with hypothalamic hamartomas were also excluded. The study was approved by our institutional ethics committee. Results: Sixteen patients (nine males, seven females) met our criteria and constituted our study population (Table1). Ten (62.5%) patients had epilepsy surgery, 9 of which had prior intracranial study. In these 9 patients, the epileptogenic focus was circumscribed to the right inferior frontal gyrus (n = 1), right superior temporal gyrus (n = 1), right inferior frontal gyrus and anterior insular cortex (n = 1), medial temporal lobe (n = 2), junction between anterior insular cortex and posterior orbital frontal gyrus (n = 1), frontal operculum and anterior insular cortex (n = 1), right anterior cingulum gyrus (n = 1), left medial frontal cortex (supplementary motor area, anterior cingulum gyrus and inferior frontal gyrus) (n = 1) . The remaining patient was operated based on the presence of right mesial temporal lobe sclerosis and congruent electrophysiological and functional findings. Seizure-freedom was attained in 7 out of these 10 operated patients. The remaining 6 (37.5%) non-operated patients, the epileptogenic focus was located to the left medial temporal lobe (n = 1; mesial temporal sclerosis on MRI), left superior frontal gyrus (n = 1; encephalomalacia on MRI), lateral temporal neocortex (n = 2; MEG cluster), multifocal left frontal on SEEG and right insula on MEG (n = 1) and undetermined (n = 1). Conclusions: Our data suggest that laughing is a poorly localizing feature as GS may be encountered in several areas of the frontal and temporal network: medial temporal, lateral temporal, insula, inferior frontal gyrus, orbitofrontal cortex, medial frontal gyrus, superior frontal gyrus.