What is a migraine?

The migrainous patient appears to differ in reaction to stress or environmental changes from nonmigrainous subjects quantitatively rather than qualitatively. An inherited pattern of monoamine metabolism may render the patient more susceptible to such changes, which represent a threat, real or imagined, to the integrity of the brain. The migraine attack may thus be interpreted as a neurohumoral reaction aimed at protecting the brain from some noxious influence by shunting blood away from the cortex. The headache itself may be a by-product of such a reaction, serving, like any pain, to alert the organism to potential danger. The predominantly unilateral site of migraine remains unexplained. A more comprehensive clinical classification of migraine is proposed in the hope that certain entities may prove to correlate with variations in pathophysiology and thus permit more selective therapy.