Migraine and risk of subarachnoid haemorrhage: a population-based case-control study.

OBJECTIVE: Evidence exists for an association between migraine and ischaemic stroke, but there is uncertainty about whether migraine is a risk factor for subarachnoid haemorrhage (SAH). METHODS: A multi-centre, population-based, case-control study using cases of first-ever SAH during 1995-98 and matched controls in four study centres in Australia and New Zealand. Self- or proxy-reported history, frequency and characteristics of headaches, classified according to 1988 International Headache Society diagnostic criteria. RESULTS: 206 of 432 (48%) cases and 236 of 473 (50%) controls had a history of headaches. The frequency and characteristics of headaches were similar between the two groups. No association was found in logistic regression analyses for history or frequency of headaches, or migraine headaches. CONCLUSIONS: No evidence was found for an association between recurrent headaches and SAH. Such information is important for counselling patients and families about the significance of past and ongoing headaches in relation to this illness.