: A Multicenter Study Evaluating the Efficacy and Safety of BOTOX® (Botulinum Toxin Type A) Purified Neurotoxin Complex as Headache Prophylaxis in Migraine Patients with 15 or More Headache Days per 4-Week Period in a 24-week, Double-Blind, Randomized, Placebo-Controlled, Parallel-Group Phase Followed by a 32-Week Open-Label Extension Phase, Allergan.