[Current viewpoints on etiology and physiopathology of migraine]

Migraine is an inheritable disease, and the mutation causing a rare variant of migraine (familial hemiplegic migraine) has now been demonstrated. The mutated gene encodes a subunit of a brain-specific calcium channel in cell membranes. Brains of patients with recurrent migraine attacks seem to behave differently from other brains, also when examined outside attacks, in that they commonly demonstrate lack of habituation when exposed to serial stimuli. The patho-physiological process of the attack might well consist of a spreading cortical depression starting in the occipital region and gradually involving other parts of the cortex. It is primarily a cerebral process secondarily accompanied by reduced cerebral blood flow, later converting into increased flow. The pain of migraine probably is mediated by way of the trigeminal nerve which releases vasoactive peptides leading to dilatation of the greater blood vessels. During an attack there is increased metabolism in cranial parts of the brain stem, demonstrated as areas of increased blood flow in PET studies. This increased metabolism persists even when the symptoms of migraine have disappeared after drug treatment, perhaps because the migraine attacks may be generated in this region. The primary dysfunction in migraine probably is located in the brain rather than in blood vessels.