Introduction: Chronic migraine is a recent diagnostic term that has undergone evolution from its original description. Clinically it has been believed that medication overuse contributed to its development and would block attempts at prevention. Previous studies with Botulinum Toxin Type A have demonstrated that it is effective even in patients with medication overuse. This study undertakes to examine the effects of Botulinum Toxin Type A in the absence of medication overuse in patients with chronic migraine.
Study design: Double-blind placebo-controlled randomized trial of Botulinum Toxin Type A 100 units administered in a fixed dose and site paradigm.
Patients: In total, 86 patients were enrolled. A total of 60 patients were randomized and 41 patients were treated with the study medication or placebo. Five patients failed to complete the study, which lasted 4 months after the study medication was injected.
Results: Botulinum Toxin Type A was statistically superior to placebo for the primary endpoint of reduction in migraine headache episodes. Six patients on Botulinum Toxin Type A compared with 3 patients on Placebo had at least a 50% reduction in their migraine episodes. Active treatment was superior to placebo for the secondary endpoints of total headache days, headache index, and quality of life measures. It showed numerical superiority to placebo for acute medication use and Migraine Disability Assessment Scores. Adverse events were rare and similar in both treatment groups.
Conclusions: The use of Botulinum Toxin Type A may be an effective treatment for chronic migraine when the patient does not have concomitant medication overuse. It was well tolerated in this trial.