433: The topographical relationship between the source localization of interictal and ictal EEG discharges recorded with subdural grid electrodes using low-resolution electromagnetic tomography (sLORETA)

Abstract

Purpose: In patients with medically refractory partial epilepsy, the topographic relationship between the location and the extent of the irritative zone, ictal onset zone, and the epileptogenic zone is controversial. Previous studies investigating the relationship between these zones have been based on a two-dimensional analysis of scalp or intracranial EEG recording, which can give misleading information regarding location of the underlying source generators. In this study patients who underwent chronic intracranial EEG monitoring with subdural electrodes, source localization was utilised using low resolution electromagnetic tomography (sLORETA) and co-registration of MRI and CT images, to examine the three-dimensional topographic relationship of the source of the interictal spikes with the ictal onset zone and regions of immediate spread.