The purpose of this study is to collect subject data to evaluate the rate of sudden unexplained death in epilepsy (SUDEP) with bilateral neurostimulation of the anterior nucleus of the thalamus in people diagnosed with refractory epilepsy. The data obtained from the physician initiated studies will be pooled with data collected in Medtronic-sponsored studies to assess SUDEP risk.

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.

This is a multi-center, retrospective and prospective clinical study in patients previously implanted with devices that provide bilateral neurostimulation of the anterior nucleus of the thalamus during non-Medtronic-sponsored studies.

Inclusion Criteria:

• Have received bilateral AN stimulation of the anterior nucleus of the thalamus (AN) for epilepsy or are receiving it at the time of enrollment
• For patients with therapy active at the time of enrollment, ability of the patient or legal representative to understand and provide signed consent for participating in the study
• For patients with therapy permanently discontinued or died at time of enrollment, the IRB/REB has approved a waiver allowing collection of the data OR the ability of the patient or legal representative to understand and provide signed consent/medical authorization

Exclusion Criteria:

• None

The study will initially include five sites that conducted physician-sponsored studies in the US and Canada. Centers may be added as additional patients are identified.