Comparing noninvasive dense array and intracranial electroencephalography for localization of seizures.

Objective: To compare the localization of the seizure onset zone estimated from ictal recordings with high spatial resolution, 256-channel scalp dense array electroencephalographic video long-term monitoring (LTM) with the aid of source analysis with that obtained from subsequent intracranial ictal recordings.

Methods: Ten patients with medically refractory epilepsy, all surgical candidates, underwent intracranial LTM after standard noninvasive evaluation failed to provide adequate localizing information regarding ictal origins. Before invasive studies, all patients underwent dense array electroencephalographic LTM in which habitual clinical seizures were recorded for each patient.