Patients with refractory epilepsy who are candidates for a treatment with vagus nerve stimulation will be prospectively randomized into 3 arms with different vagus nerve stimulation paradigms. Vagus nerve stimulation parameters are programmed and adjusted during outpatient clinic visits, within the normal clinical practice.

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