What is a migraine headache?

Migraine without aura is a recurrent headache disorder manifesting in attacks lasting 4-72 hours. Typical characteristics of the headache are unilateral location, pulsating quality, moderate or severe intensity, aggravation by routine physical activity, and association with nausea and/or light and sound sensitivities. 

Chronic migraine is headache occurring on 15 or more days per month for more than 3 months, which, on at least 8 days or more per month, has the features of migraine headache. Episodic migraine is less than 15 headache days per month.

Migraine headache is second highest cause of disability worldwide and affects more than 12 percent of the population.