A Study With an Open-label Extension Phase to Evaluate the Efficacy and Safety of Perampanel (E2007) Administered as an Adjunctive Therapy in Subjects With Refractory Partial-onset Seizures

Inclusion Criteria 1. Male or female and greater than or equal to 12 years of age; 2. Have a diagnosis of epilepsy with partial seizures with or without secondarily generalized seizures 3. Participants with computed tomography (CT) or magnetic resonance imaging (MRI) diagnosis within the last 10 years (for adults) and 5 years (for adolescents) prior to visit 1 that ruled out progressive central nervous system (CNS) disorders, example, neurodegenerative disorders, brain tumors. For participants without existing CT or MRI results, CT or MRI was performed at or after Visit 1 but results evaluation was performed by Visit 2 4. Participants who had been treated for at least 12 weeks but confirmed to be uncontrolled with more than one standard antiepileptic drug (AED) for 2 years before enrollment 5. During the 6-week Prerandomization Phase participants must have had greater than or equal to 5 partial seizures per 6-week 6. Are currently being treated with stable doses and administrations of 1, 2, or a maximum of 3 approved AEDs. Only 1 inducer AED (defined as carbamazepine, phenytoin or oxcarbazepine only) out of the maximum of 3 AEDs is allowed Exclusion Criteria 1. Presence of nonmotor simple partial seizures only; 2. Presence of primary generalized epilepsies or seizures, such as absences and/or myoclonic epilepsies; 3. Presence or previous history of Lennox-Gastaut syndrome; 4. A history of status epilepticus within 1 year prior to screening 5. Seizure clusters where individual seizures cannot be counted 6. A history of psychogenic seizures within 5 years prior to screening