• Change in the monthly (28 days) migraine period rate from the Prospective Baseline Period to the Core Double-Blind Phase.
  

• Proportion of patients responding to treatment.Change from Baseline Phase to Core Double-Blind Phase in number of monthly migraine attacks,monthly migraine days, number of days/month requiring rescue medication,and Health Related Quality of Life measures
  

This is a randomized, double-blind, placebo-controlled, parallel-group, multicenter study to evaluate the efficacy and safety of two doses of topiramate versus placebo and propranolol in the prevention of migraine headaches. The study consists of 4 phases: Baseline Phase (evaluation of eligibility criteria and tapering of any migraine prophylaxis medications patients are taking), Core Double-Blind Phase (patients are randomized to receive either 100 milligrams[mg]/day topiramate, 200mg/day topiramate, 160mg/day propranolol or placebo for a total of 26 weeks), Blinded Extension Phase (patients continue the same dose of medication until the sponsor terminates the study or a patient withdraws from the study), and Taper/Exit Phase (medication of patients exiting from the study is tapered over 7 weeks). The primary hypothesis is that one or two topiramate doses (100, 200 mg/day) will be superior to placebo in the prophylaxis of migraine based on the change in the monthly (28 days) migraine period rate from the prospective Baseline Phase to the Core Double-Blind Phase. Oral medication (100 milligrams[mg]/day topiramate, 200mg/day topiramate, 160mg/day propranolol, or placebo) during the 26-weeks Core Double-Blind Phase. Doses may be continued until the termination of the study or withdrawal by the patients during the Blinded Extension Phase.