Chronic migraine.

The second edition of the International Classification of Headache Disorders revised in 2006 (ICHD-2R) gives a definition which requires 15 or more headache days per month over the past 3months with at least eight headache days per month that meet criteria for migraine without aura or that responds to migraine specific treatment. Approximately 2% of the global population suffers of chronic migraine (CM). Frequency of headache and degree of disability distinguish CM from episodic migraine (EM). There is a high frequency of medication overuse. The treatment depends on evaluation with education, lifestyle modifications, and trigger management, behavioral and pharmacologic therapies.