Evaluating E2007 (Perampanel) in Patients With Painful Diabetic Neuropathy (PDN) or Post-Herpetic Neuralgia (PHN)

Inclusion Criteria: Each patient must meet all of the following criteria to be enrolled in this study: 1. Met and continues to meet all inclusion and none of the exclusion criteria for the preceding PDN or PHN study and received study drug or placebo under double-blind conditions. 2. Completed the preceding double-blind study End of Treatment (EOT) Visit no more than 12 weeks prior to Baseline (Visit 1) for the open-label study. The eligibility status of patients who do not enroll during this 12 week period will be evaluated on a case by case basis via discussion between the Investigator and the Sponsor. 3. Males and females ≥18 years of age. Female patients should be either of nonchildbearing potential as a result of surgery or menopause (1 year after onset), or of childbearing potential and practicing a medically acceptable method of contraception (e.g., abstinence, a barrier method plus spermicide, or intrauterine device \[IUD\]) for at least 1 month before the Baseline Visit (Visit 1) and for 1 month after the end of the study (Visit 16). They must also have a negative pregnancy test at Baseline (Visit 1). Female patients using hormonal contraceptives must also be using an additional approved method of contraception (e.g., a barrier method plus spermicide or IUD) throughout the study. 4. Provide written informed consent prior to entering the study and prior to undergoing any study-related procedures. 5. Is reliable, willing, and able to cooperate with the study procedures. Exclusion Criteria: Patients who meet the following criterion will be excluded from this study: 1. Patients who discontinued early for any reason from the preceding double-blind study. 2. Patients who have a clinically significant finding(s) that would make them unsuitable for the study in the opinion of the investigator or Sponsor.