The risk of stroke in patients with migraine and implications for migraine management.

Assessing the risk of stroke in persons with migraine is complicated by the intricate relationship between these two conditions. Both migraine and stroke are common and co-morbidity may, in some cases, be coincidental. Given the overlap of clinical symptoms in stroke and migraine, each condition may also mimic the other. Numerous studies have, however, shown that migraine is an independent risk factor for stroke both during, and remote from, the migraine attack. Women of childbearing age and those with aura are at greatest risk of migraine-related stroke. Additional risk of stroke in migraineurs occurs in those using oral contraceptive pills and who smoke cigarettes. Elevated blood pressure, an important stroke risk factor, is less common in migraineurs. Acquired antiphospholipid antibodies, not clearly a cause of migraine per se, may raise the risk of infarction in migraineurs. Hereditary conditions, including CADASIL (cerebral autosomal dominant arteriopathy with sub-cortical infarcts and leukoencephalopathy), MELAS (mitochondrial myopathy, encephalopathy, lactacidosis and stroke) and hereditary haemorrhagic telangiectasia, appear to predispose to both migraine and stroke. Purported mechanisms for migraine-associated stroke include involvement of the vasculature (including vasospasm, arterial dissection and small vessel arteriopathy), hypercoagulability (elevated von Willebrand Factor, platelet activation) and elevated risk of cardioembolism (patent foramen ovale, atrial septal aneurysm). Triptans and ergotamines, used to treat acute migraine attacks, appear to be safe in low-risk populations. These medications should be avoided in persons with haemiplegic migraine, basilar migraine, vascular risk factor and prior cerebral or cardiac ischaemia.