Arteriovenous malformations: epidemiology and clinical presentation.

Arteriovenous malformations (AVMs) of the brain are relatively rare congenital developmental vascular lesions. They may cause hemorrhagic stroke, epilepsy, chronic headache, or focal neurologic deficits, and the incidence of asymptomatic AVMs is increasing due to widespread availability of noninvasive imaging methods. Since the most severe complication of an AVM is hemorrhagic stroke, most epidemiologic studies have concentrated on the hemorrhage risk and its risk factors. In this article, the authors discuss the epidemiology, presenting symptoms, and hemorrhage risk associated with brain AVMs.