Trial Comparing Different Stimulation Paradigms in Patients Treated With Vagus Nerve Stimulation for Refractory Epilepsy

Inclusion Criteria: * 16 years or older * At least 1 seizure/month with alteration of consciousness * Documented seizure diary, at least 3 months prior to implantation (baseline) * No change in anti-epileptic drugs 1 month before implantation * At least one or more AEDs Exclusion Criteria: * Active cardiac, pulmonary or gastrointestinal disease * Vagotomy * Concomitant use of an investigational drug * Unstable medical condition * Unstable psychiatric condition