Arteriovenous Malformation

Arteriovenous malformations (AVMs) are defects of the circulatory system that are generally believed to arise during embryonic or fetal development or soon after birth. They are comprised of snarled tangles of arteries and veins. Arteries carry oxygen-rich blood away from the heart to the body’s cells; veins return oxygen-depleted blood to the lungs and heart. Seizures and headaches are the most generalized symptoms of AVMs, but no particular type of seizure or headache pattern has been identified.

Seizures can be partial or total, involving a loss of control over movement, convulsions, or a change in a person’s level of consciousness. Headaches can vary greatly in frequency, duration, and intensity, sometimes becoming as severe as migraines. Sometimes a headache consistently affecting one side of the head may be closely linked to the site of an AVM. More frequently, however, the location of the pain is not specific to the lesion and may encompass most of the head. AVMs are congenital lesions composed of a complex tangle of arteries and veins connected by one or more fistulae. The vascular conglomerate is called the nidus.

Invasive treatment is recommended for younger patients with 1 or more high-risk features for an AVM rupture. Older individuals and patients with no high-risk features may be best treated through management of the medical aspects of the illness alone in such patients, anticonvulsants for seizure control and appropriate analgesia for headaches may be the only treatment recommendations necessary. Invasive treatment of AVMs may include endovascular embolization, surgical resection, and focal beam radiation, alone or in any combination. Hemorrhage: In population-based studies, 38-70% of brain AVMs present initially with hemorrhages. The overall risk of intracranial hemorrhage in patients with known AVM is 2-4% per year.