 The investigators hypothesis is that SUDEP partly results from a post-ictal apnea promoted by a GTCS-induced massive release of endogenous opioids, and that an opioid antagonist could represent an effective preventive treatment of SUDEP. This could be achieved by chronic administration of Naltrexone, an opioid antagonist that has been used in a large population of patients with chronic alcoholism at high risk of seizures, without showing any pro-convulsant effect. This is a crucial feasibility issue since antagonising a mechanism thought to participate to seizure termination could theoretically aggravate seizures. 