Noninvasive Functional Neuroimaging of Electrophysiological Brain Activities in Epilepsy Patients

Abstract

Epilepsy represents a chronic neurological disease that affects roughly 50 million people worldwide, and up to 30% of the patients do not respond effectively to medication. For those patients who experience frequent seizures and whose lives are greatly impacted, resective surgery removing epileptogenic foci is the last viable treatment option. The aim of this research is to develop and evaluate the EEG based noninvasive neuroimaging approaches to study the epileptogenic foci of epilepsy patients. Toward this goal, we have i) studied the feasibility of performing source connectivity based spatio-temporal dipole method for localizing ictal sources; ii) obtained the high-density scalp EEG recording in epilepsy patient and studied the effect of electrode numbers on source localization accuracy; iii) utilized the dynamic seizure imaging approach to track seizure activities in pediatric epilepsy patients; iv) established the high-frequency source imaging approach to image the scalp recorded pathological high-frequency activity in epilepsy patients; v) developed a method to estimate the source extent from noninvasive scalp recording. The methods were rigorously tested in a series of computer simulations and in different groups of epilepsy patients. Patient-specific structural MRI based head model was used to achieve high-accuracy volume conduction modeling of the brain source. Clinical diagnoses such as seizure onset zone of intracranial recording, surgical resection, and surgical outcome were used to evaluate the imaging approaches. The present study demonstrates the feasibility of utilizing high-density EEG recordings and high-resolution source imaging in localizing epileptic activity and indicates its potential application in pre-surgical planning of epilepsy patients.