A Trial to Evaluate the Efficacy and Safety of Adjunctive Therapy With Lacosamide in Adults With Partial-Onset Seizures

Inclusion Criteria: * Subject has had an Electroencephalogram (EEG) and a brain Computerized Tomography (CT) scan or Magnetic Resonance Imaging (MRI) exam consistent with a Diagnosis of Epilepsy with Partial-Onset Seizures according to the International Classification of Epileptic Seizures (1981) * Subject must have been observed to have Partial-Onset Seizures for at least the previous 2 years despite prior therapy with at least 2 Anti-Epileptic Drugs (AEDs)(concurrently or sequentially) and must have been observed to have on average at least 4 Partial-Onset Seizures per 28 days with a seizure-free phase no longer than 21 days in the 8-Week Period prior to entry into the Baseline Period. In the case of Simple Partial Seizures, only those with motor signs will be counted towards meeting the inclusion criterion * Subjects must be on a stable dose regimen of at least 1, but no more than 3 AEDs (concurrent stable Vagus Nerve Stimulation (VNS) is not counted as an AED). The VNS must have been in place for at least 6 months prior to study entry. The dosage of concomitant AED therapy and the settings of the VNS must be kept constant for a period of at least 4 weeks prior to entry into the Baseline Period * Minimum Body Weight of 40 kg Exclusion Criteria: * Subject has a lifetime history of suicide attempt (including an active attempt, interrupted attempt, or aborted attempt) or has a suicidal ideation in the past 6 months as indicated by a positive response ("Yes") to either Ques…