Evaluate the Efficacy of BGG492 as Adjunctive Treatment in Patients With Refractory Partial Onset Seizures

Inclusion Criteria: * Outpatients ≥ 50 kg (110 lb) of weight * A diagnosis of epilepsy (≥ 2 years prior to screening) with partial seizures with or without secondarily generalized seizures * Uncontrolled partial seizures despite having been treated with at least two different AEDs within the last 2 years prior to screening. * Treated with a stable dose of 1-2 AEDs * At least 4 partial seizures during the 4-week baseline period and at least 4 partial seizures during the 4 weeks prior to the baseline period. * No 28-day seizure-free period during the 8 weeks preceding randomization * Positive biomarker screening Exclusion Criteria: * Presence of only non-motor simple partial seizures * History of psychogenic seizures * Absences, myoclonic seizures e.g. in the context of primary generalized epilepsy; * Previous history of Lennox-Gastaut syndrome * Pregnant or nursing (lactating) women * Status epilepticus or seizure clusters, according to the judgement of the investigator, occurring within 52 weeks prior to randomization Other protocol-defined inclusion/exclusion criteria may apply