Migraine and ischemic stroke: a debated question.

Numerous epidemiologic observations reporting high prevalence of migraine among young individuals with stroke as well as dysfunction of cerebral arteries during migraine attacks prompt speculation on the existence of a comorbidity between the two disorders. The recent finding of silent infarct-like brain lesions in migraineurs reinforced this hypothesis and raised questions on whether migraine may be a progressive disorder rather than simply an episodic disorder. Stroke can occur during the course of migraine attacks with aura, supporting the assumption of a causal relation between the two diseases. Migraine may accentuate other existing risk factors for stroke, and both jointly increase the risk of cerebral ischemia outside of migraine attacks. In this regard, the role of migraine might be that of predisposing condition for cerebral ischemia. Migraine and ischemic stroke may be the end phenotype of common pathogenic mechanisms. Evidence of a migraine-stroke relation in cases of specific disorders, such as CADASIL (cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy) and MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes), strongly supports this concept. Finally, acute focal cerebral ischemia can trigger migraine attacks, and, thus, migraine may be the consequence of stroke. In this paper, we will review contemporary epidemiologic studies, discuss potential mechanisms of migraine-induced stroke and comorbid ischemic stroke, and pose new research questions.