Rate , Predictors and Outcome of Chronic Migraine

Nowadays, headache has been considered as one of the top global disabling medical conditions.1 Migraine is an important type of headache, and one of the chronic multifaceted neuro-inflammatory disorders.2 It is characterized by recurrent throbbing headache pain that typically affects one side of the head, and is often accompanied by nausea and disturbed vision. Migraine headache accounts for 1.4% of all neurological and mental disorders.2 It was reported that the estimated lifetime prevalence of migraine ranged 12%-18%.3 Chronic migraine is defined by the International Classification of Headache Disorders - ICHD-3 as having headaches for ≥ 15 days per month, for ≥ 3 months , which ≥ 8 days/month are linked to migraine. Chronic migraine affects around 1%-4% of the population and chronic tension-type headache about 2.2%.4 Approximately 25%-50% of those affected also have medication overuse headache, which has a population prevalence of 1%.5 Chronic headache is a severely disabling long-term condition, with higher symptom ,frequency and severity than episodic headache.6