Chronic migraine: a therapeutic challenge for clinicians.

Chronic migraine is a common disabling condition. Severe migraine attacks should be treated with triptans, but these agents are contraindicated in patients with vascular problems and may not be effective or tolerated in around one third of the patients. New acute migraine therapies without vasoconstrictive activity and triptan-specific side effects are emerging. For the prophylaxis of chronic migraine, only topiramate and OnabotulinumtoxinA have been shown to be effective in placebo-controlled randomized trials, so novel therapeutic strategies are needed. The growing understanding of the pathophysiology of chronic migraine will contribute to the identification of new treatment targets.