1. Examine the role of post-ictal EEG suppression as a biomarker of SUDEP risk in a nested case-control study of medically refractory epilepsy with video-EEG monitoring. We hypothesize that cases with SUDEP will have longer EEG suppression and periods of post-ictal coma following a generalized tonic-clonic seizure compared to living controls. 2. Examine clinical, electrophysiological and imaging risk factors for SUDEP in the case-control study. These factors include presence of nocturnal seizures, seizure characteristics, duration and burden of epilepsy, interictal and ictal EKG changes, and volume of autonomic brain regions on structural MRI.