Migraine is a neurological syndrome characterized by altered bodily perceptions, headaches, and nausea. Physiologically, the migraine headache is a neurological condition more common to women than to men. The word migraine was borrowed from Old French migraigne (originally as "megrim", but respelled in 1777 on a contemporary French model). The French term derived from a vulgar pronunciation of the Late Latin word hemicrania, itself based on Greek hemikrania, from Greek roots for "half" and "skull". The typical migraine headache is unilateral and pulsating, lasting from 4 to 72 hours; symptoms include nausea, vomiting, photophobia (increased sensitivity to bright light), and hyperacusis (increased sensitivity to sound); approximately one third of people who suffer migraine headache perceive an aura — unusual visual, olfactory, or other sensory experiences that are a sign that the migraine will soon occur.
Initial treatment is with analgesics for the head-ache, an anti-emetic for the nausea, and the avoidance of triggering conditions. The cause of migraine headache is idiopathic; the accepted theory is a disorder of the serotonergic control system, as PET scan has demonstrated the aura coincides with diffusion of cortical depression consequent to increased blood flow (up to 300% greater than baseline). There are migraine headache variants, some originate in the brainstem (featuring intercellular transport dysfunction of calcium and potassium ions) and some are genetically disposed. Studies of twins indicate a 60 to 65 percent genetic influence upon their propensity to develop migraine headache. Moreover, fluctuating hormone levels indicate a migraine relation: 75 percent of adult patients are women, although migraine affects approximately equal numbers of prepubescent boys and girls; propensity to migraine headache is known to disappear during pregnancy, although in some women migraines may become more frequent during pregnancy.