This was an open-label extension (OLE) study for subjects who completed one of the following double-blind, placebo-controlled, Phase 3 studies: E2007-G000-304 (NCT00699972), E2007-G000-305 (NCT00699582), and E2007-G000-306 (NCT00700310). This OLE study consisted of 2 phases: an Open-label Treatment Phase (comprised of a 16-week blinded Conversion Period and a 256-week Maintenance Period) and a Follow-up Phase (4 weeks). During the Conversion Period, subjects and investigators remained blinded to the treatment received in the previous DB study. To achieve this, all subjects continued to take 6 tablets of study medication (2 mg perampanel or matching placebo) or fewer as they were instructed during the core Double-Blind (DB) study. During the open-label Maintenance Period, subjects were treated with the perampanel dose that provided the best combination of individual efficacy and tolerability.