A Double-blind, Placebo-controlled Study of Levetiracetam in Epilepsy Patients With Generalized Tonic-clonic Seizures (Except Partial Seizures Evolving to Secondarily Generalized Seizures)

Inclusion Criteria: * An epilepsy patient with generalized tonic-clonic seizures that are classifiable according to the ILAE classification of epileptic seizures (Epilepsia, 1981) * A patient on a stable dose of 1 or 2 anti-epileptic drugs for the last 4 weeks (potassium bromide and sodium bromide for the last 12 weeks) prior to and during the combined baseline period Exclusion Criteria: * Presence of any sign (clinical or imaging procedures) suggesting a progressive brain lesion/disease, in particular, progressive disorder with epileptic seizures * Diagnosis of Lennox-Gastaut Syndrome * Confirmed focal epilepsy based on clinical signs (seizure types), with consistent electroencephalogram and magnetic resonance imagining features * A history of convulsive or non-convulsive status epilepticus while taking concomitant anti-epileptic drugs for the last 3 months prior to Visit 1