Abstracts

To describe the ictal onset patterns during ECoG in a pediatric population and determine the relationship of these patterns to histopathology and outcome., The ictal onset patterns of 26 patients (10 mos to 14 years old) who underwent ECoG between May 1997 and July 2004 were retrospectively reviewed. Clinical history, neuroimaging, surgical, histopathological records were reviewed and correlated with the identified ictal patterns. Post-operative seizure outcome was assessed using the Engel classification. A minimum of one year follow up was required., Ictal onset patterns identified four types of ictal zones: focal, regional, multifocal and diffuse. Ictal onset pattern identified five types of activities in the delta, theta, alpha, low voltage in the beta range, and onset with attenuation of voltage. Focal and regional ictal onset patterns with low voltage fast frequencies were more commonly associated with either gliosis or focal cortical dysplasias. Eight patients had gliosis, 8 patients had focal cortical dysplasias and 2 patients had Rasmussen encephalitis. Ictal onset patterns identified 18 children who underwent resection. Five patients were Engel I, 3 were Engel II, 1 was Engel III and 9 were Engel IV. Ictal onset patterns identified 8 non-resectable patients, Ictal onset patterns in children undergoing ECoG help to identify successfully the resectable epileptogenic zone. Ictal onset patterns in children correlated with a well identified ictal zone can lead to total improvement, partial improvement or to infrequent seizures in at least 50% of young children who undergo epilepsy surgery.,