Medtronic is conducting a pivotal clinical trial entitled Stimulation of the Anterior Nucleus of the Thalamus in Epilepsy (SANTÉ). One of the requirements of the SANTÉ study is to evaluate the rate of sudden unexplained death in epilepsy (SUDEP). Medtronic is aware of approximately 18 subjects with various types of epilepsy that have been treated with neurostimulation of the anterior nucleus of the thalamus outside the SANTÉ trial under five physician-sponsored studies. This protocol will initially collect information regarding the physician-sponsored study subjects' status. The goal of this study is to pool these data with the SANTÉ data for the purpose of estimating the SUDEP rate.