Experience with botulinum toxin in chronic migraine.

[OBJECTIVE] The purposes of this study were to describe our 16-month experience with onabotulinumtoxinA (OnabotA) for the treatment of chronic migraine (CM) in the Spanish province of Segovia, evaluate its benefits, and determine clinical markers of good response to treatment.

[PATIENTS AND METHODS] Prospective study of patients with CM who received OnabotA for 16 months. The effectiveness of OnabotA was evaluated based on the reduction in the number of headache days, pain intensity, and side effects. We used two-way analysis of variance (ANOVA) to assess the effects of treatment according to the time factor. We studied the correlation between treatment effects and other variables using a linear regression model to establish the clinical markers of good response to treatment.

[RESULTS] We included 69 patients who met the diagnostic criteria for CM. Patients underwent an average of 2 infiltrations. Mean age was 43 years; 88.4% were women. The number of headache days and pain intensity decreased significantly (P < .005); improvements remained over time. We found a negative correlation between the reduction in pain intensity and the number of treatments before OnabotA.

[CONCLUSION] The beneficial effects of OnabotA for CM continue over time. OnabotA is a safe and well-tolerated treatment whose use for refractory CM should not be delayed since early treatment provides greater benefits.