Botulinum therapy for chronic migraine.

Chronic migraine (CM) is an important cause of chronic daily headache (CDH), a common severe headache syndrome. Patients with CM are significantly disabled from employment and overuse pain relieving medications. CM is a difficult condition to treat. Overuse of abortive medications and limited benefit from oral preventive medications are an important problem in managing this condition. Recent randomized controlled trials evaluating the efficacy of botulinum toxin A (BoNT-A) have confirmed its efficacy for CM prophylaxis. BoNT-A is a safe drug with no systemic reactions in clinical trials for headache.