5. Currently treated with 1 or 2 AEDs (any except OXC), in a stable dose regimen during at least 1 month prior to screening. Patients using vigabatrin should have been on this medication for at least 1 year with no deficit in visual field identified (a confirmatory test should be available within 1 month before study entry). The device for VNS should be implanted at least 6 months before screening; parameters need to be stable for at least 1 month prior to screening (VNS will not be counted as concomitant AED).