Noninvasive Epileptic Seizure Localization from Stochastic Behavior of Short Duration Interictal High Density Scalp EEG Data

Abstract

The stochastic behavior of the phase synchronization index (SI) in different EEG bands was examined for noninvasive localization of the epileptogenic areas from the short duration (30-60s), seizure-free and spike-free high density (256 channel) scalp EEG data. We also examined the cross-frequency and cross-electrode coupling in different EEG bands. EEG data of four subjects was used. The seizure areas were localized with subdural recordings with an 8×8 grid electrode array. It was found that the stochastic behavior of the SI in low gamma band (30-50Hz) was higher in epileptogenic areas. The beta (12-30Hz) band also showed similar tendencies. The stochastic behavior in theta (3-7Hz) band was depressed in the seizure area while it was widespread in large areas over the scalp in the alpha (7-12Hz) band. The stochastic behavior of the cross-frequency and cross-electrode couplings in theta-gamma, alpha-gamma and beta-gamma bands were decreased in the seizure areas for all four subjects. These findings suggest that it is possible to localize the epileptogenic areas from the short duration seizure-free and spike-free high density scalp EEG data.