Botulinum toxin for chronic migraine.

Chronic migraine (CM) is a common primary headache occurring on 15 or more days per month and for more than three months. It presents a considerable therapeutic challenge. Botulinum toxin (BoNT) has emerged as a promising treatment for CM, particularly in patients unresponsive to standard pharmacological therapy or experiencing adverse effects. Its therapeutic benefit is based on blocking the release of nociceptive neuropeptides modulating pain pathways. Clinical efficacy and safety of BoNT have been demonstrated in multiple randomized controlled CM trials showing a significant reduction of headache frequency. This review provides an overview of efficacy and safety of BoNT for CM.