Natural history of arteriovenous malformations: presentation, risk of hemorrhage and mortality.

Brain arteriovenous malformations (AVMs) are highly complex vascular lesions, which may become symptomatic by causing hemorrhagic stroke, epilepsy, chronic headache and/or focal neurological deficits. An increasing number of AVMs are also found incidentally in MRI and CT scans performed for other reasons. It is mandatory to understand the natural history and prognosis of these malformations when evaluating the risks that may be associated with the treatment. In this review, we discuss the symptomatology, hemorrhage risk and mortality associated with their natural course.