Context

Migraine is a common chronic intermittent neurovascular headache disorder. The prevalence is about the same in different countries and affects about 10–20% of the adult population.1 Women are affected more often than men. Most patients experience their first attacks before the age of 40. Migraine is characterised by a unilateral pulsating pain, aggravated by physical activity, and associated symptoms are nausea, photo- and phonophobia. Up to 30% of patients experience an aura with transient neurological symptoms (eg, scintillary scotoma, speech disturbance or sensory symptoms). About 5% experience a migraine aura without headache. Clinically, migraine forms are defined as migraine with aura (MA) and migraine without aura (MO). Diagnostic criteria for migraine are defined in the International Classification of Headache (ICH) disorders; the first version was edited in 19882 and the revised second edition is from 2004.3

Several studies have shown that patients with migraine have an increased risk for ischemic stroke. Earlier studies indicated an increased risk of ischemic stroke in both MA and MO, confirmed in a systematic review and meta-analysis of observational studies in 2004.4 However, during the last few years, new studies in large cohorts have re-investigated the association between migraine and vascular events, and a new systematic review and meta-analysis, conducted in 2009, established an association between MA and ischemic stroke.5 The increased risk for ischemic stroke seems to be highest among smoking women, <45 years of age, using oral contraceptives.

Two new prospective large cohort studies have recently been performed on migraine. First, an American investigation looking for association between hemorrhagic stroke and migraine using the study population in the Womens Health Study (WHS),6 and second, an Icelandic study on whether migraine in mid-life is associated with mortality from cerebrovascular disease, other causes and all …