An association between migraine and ischemic stroke has been noted in several observational studies, particularly among patients who experience migraines with an aura. But whether an association exists between migraine and hemorrhagic stroke is less clear. To evaluate the relationship between migraine and hemorrhagic stroke (either intracerebral or subarachnoid hemorrhage), researchers in Italy conducted a meta-analysis of eight studies involving a total of 1,600 hemorrhagic strokes: four case-control trials and four with a cohort design.

Overall, the pooled adjusted effect estimate of hemorrhagic stroke was 1.48 among patients with any migraine, as compared with controls; taken separately, the odds of stroke in the case-control studies were 1.41 and the odds in the cohort studies were 1.47. Subanalyses showed that in patients who experience migraine with an aura, the pooled adjusted effect estimate of hemorrhagic stroke was 1.62, although that value wasn't significant, probably because only three studies reported data on migraine type. Data concerning women with migraines (of any type) showed an adjusted effect estimate of 1.55, compared with controls, and the risk was slightly higher (1.57) among women younger than 45 years.

Overall, the eight studies demonstrated a relationship between migraine and hemorrhagic stroke, with a 50% higher risk among those with any migraine. The researchers couldn't clearly identify an increased risk among patients with migraines with auras, but they noted that the analysis may have had insufficient power to detect an association. And although women who experienced migraines had a higher risk of stroke, the authors state that these data should be interpreted with caution because comparable data on men were provided in only two studies and further comparison between sexes wasn't possible.

Although their analysis showed an elevated risk of hemorrhagic stroke among people who experience migraines, the authors note that the incidence is small and suggest that other factors may contribute to this association. Because the reason for this relationship is unknown, they recommended against alerting patients to the possible risk or varying from standard treatments. Instead, they assert, clinicians should focus on evaluating risk factors that could contribute to a stroke.

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