Duration of Benefit for OnabotulinumtoxinA in Treatment of Chronic Migraine

BOTOX® (Formulation Number 9060X) contains 200 International Units (IU) of Clostridium botulinum Toxin Type A, reconstituted with 4 cc of normal saline providing 5 units per 0.1 cc. At visit 2, subjects will receive their first treatment at Day 29 (+/-3 days). All subjects will receive 155 U Botulinum Toxin Type A Purified Neurotoxin Complex administered at 31 fixed-site, fixed-dose injections across seven (7) specific head/neck muscle areas. Injections will be repeated at day 113 (+/- 3 days) and at day 197 (+/- 3 days).