A Study to Evaluate Efficacy and Safety of Perampanel Administered as an Adjunctive Therapy in Pediatric Participants With Childhood Epilepsy

Inclusion Criteria: * Male or female participants. Cohort 1: age 1 month to less than 18 years; Cohort 2: age 1 month to less than 2 years at the time of informed consent/assent. Participants below the age of 1 year must have been at least 36 weeks of gestational age at birth. * Have a diagnosis of epilepsy with a pediatric epileptic syndrome (Cohort 1) or epilepsy with POS with or without secondary generalization (Cohort 2). * Have had equal or greater than 4 seizures over the 4-week interval prior to enrollment visit. * Absence of any progressive cause of epilepsy that has been confirmed clinically or based on brain imaging (example, magnetic resonance imaging \[MRI\] scan or computed tomography \[CT\] or ultrasound \[for less than 1 year old\]). * Currently maintained on stable doses of 1 to a maximum of 4 approved antiepileptic drugs (AEDs). A prescription medical marijuana (including products containing cannabidiol) is counted as 1 of the maximum of 4 allowed AEDs; however, it cannot be the only concomitant AED if this product is not an approved AED in the country where the study site is located. Doses must be stable for at least 4 weeks (at least 2 weeks for participant less than \[\<\] 6 months old) before Visit 1/Baseline or screening; only 1 enzyme-inducing antiepileptic drug (EIAED) (defined as carbamazepine, phenytoin, oxcarbazepine, or eslicarbazepine) out of the maximum of 4 AEDs is allowed. Exclusion Criteria: * Current or history of pseudo-seizures (psychoge…