Patients who have completed one of the core trials (E2007-E044-301 or E2007-A001-302) and who meet inclusion/exclusion criteria will be enrolled and will enter the Titration Phase, lasting 4 weeks (weeks 0-3) followed by the Maintenance Phase, lasting 52 weeks (weeks 4-56). All patients will receive active study drug. During the Titration Phase, patients will receive E2007 2 mg once daily (o.d.) for 2 weeks followed by 4 mg o.d. for 2 weeks. During the Maintenance Phase, patients will receive 4 mg o.d. Patients not tolerating the study drug at 4 mg, will be allowed to down titrate to 2 mg. Patients not tolerating 2 mg will be withdrawn from the study.