Migraine with aura is associated with an approximately doubled risk of stroke (5, 7, 8). The relative risk (RR) of stroke in patients with migraine with aura was found in a metaanalysis to be 2.16 (95 % confidence interval (CI) 1.53–3.03), but there was not an increased risk for migraine without aura (relative risk 1.23, CI 0.90–1.69) (7). The association is strongest in women under the age of 45 and in those with frequent migraine attacks (7, 8). Measured in absolute figures, however, the incidence of stroke in persons under the age of 45 is modest: 19 per 100 000 annually for those with migraine compared with 6 per 100 000 annually for those without migraine (9).
Recent studies indicate a higher risk also of cerebral haemorrhage (subarachnoidal haemorrhage or intracerebral haemorrhage) (5, 8, 10). A metaanalysis calculated the risk of cerebral haemorrhage to be higher in persons with migraine (relative risk 1.48, CI 1.16–1.88), but with no clear link to aura (10). Smoking and the use of contraceptive pills heighten the risk of stroke in the population with migraine with aura and in combination raise the risk sevenfold compared with women with migraine with aura who neither smoke nor use contraceptive pills (11). Despite the increased risk of stroke, it is not clear whether migraine is associated with higher mortality due to cardiovascular disease as a whole (12, 13).
Most strokes occur independently of migraine attacks. However, a rare complication of migraine, so-called migrainous infarction, is detected infarction found to occur with aura symptoms of unusually long duration (> 60 minutes) in a person with migraine with aura (14, 15). Migrainous infarction accounts for only 0.5–1.5 % of all cases of acute stroke, but up to 14 % of stroke cases in persons under 45 years old (14, 16).