Headache is one symptom of migraine; nausea and vomiting, abdominal distress, vertigo and fever are others. Perceptual alterations are also associated with migraine: photophobia, phonophobia, heightened sensitivity to olfactory stimuli and increased general irritability are often noted. Headache, however, is most debilitating.
A hypothesis is proposed describing one mechanism whereby genesis of migraine headache may occur. This mechanism is consistent with clinical and experimental observations taken from human and animal studies. Briefly, various agents or activities induce vasoconstriction of the cranial arteries in susceptible populations. Oxygenation of the brain is decreased with consequent decrease in the synthesis of serotonin, a neurotransmitter implicated in pain perception. Stimuli not normally painful, such as vasodilatation, thus become painful.