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

INTERVENTION: Trade Name: BOTOX® Product Name: BOTOX® Product Code: 9060X Pharmaceutical Form: Powder for solution for injection INN or Proposed INN: Botulinum toxin type A Current Sponsor code: AGN 191622 Other descriptive name: Botulinum toxin type A (from Clostridium botulinum) Concentration number: Vials of 100 ‐ Allergan Units Pharmaceutical form of the placebo: Powder for solution for injection Route of administration of the placebo: Intramuscular use CONDITION: Headache prophylaxis in migraine patients with 15 or more headache days per month PRIMARY OUTCOME: Main Objective: To evaluate the efficacy and safety of Botulinum Toxin Type A Purified Neurotoxin Complex compared with placebo as headache prophylaxis in migraine patients with 15 or more headache days per 4‐week period. Primary end point(s): The change from baseline in the frequency of headache episodes per 4 weeks to Week 24 Secondary Objective: To evaluate the long term safety of Botulinum Toxin Type A Purified Neurotoxin Complex as headache prophylaxis in migraine patients with 15 or more headache days per 4‐week period. INCLUSION CRITERIA: Male or female, 18 to 65 years old; history of migraine disorder as classified in ICHD‐11 (2004) Section 1 [with the exception of hemiplegic migraine (1.2.4, 1.2.5) basilar migraine (1.2.6), ophthalmoplegic migraine (13.17) or migrainous infarction (1.5.4]; four or more headache episodes with a duration of at least 4 hours during the 4‐week baseline period; fifteen or more headache days during the 4‐week baseline period with each day consisting of at least 4 hours of continuous headache; written informed consent and data protection consent. Negative pregnancy test in females of childbearing potential Are the trial subjects under 18? no Number of subjects for this age range: F.1.2 Adults (18‐64 years) yes F.1.2.1 Number of subjects for this age range F.1.3 Elderly (>=65 years) no F.1.3.1 Number of subjects for this age range