Definition of Arteriovenous malformation - cerebral:

A cerebral arteriovenous malformation is an abnormal connection between the arteries and veins in the brain that usually forms before birth.

Causes, incidence, and risk factors:

The cause of cerebral arteriovenous malformation (AVM) is unknown. The condition occurs when arteries in the brain connect directly to nearby veins without having the normal vessels (capillaries) between them.

Arteriovenous malformations vary in size and location in the brain.

An AVM rupture occurs because of pressure and damage to blood vessel tissue. This allows blood to leak into the brain or surrounding tissues, and reduces blood flow to the brain.

Cerebral AVMs occur in less than 1% of people. Although the condition is present at birth, symptoms may occur at any age. Hemorrhages occur most often in people ages 15 - 20, but can also occur later in life. Some patients with an AVM also have cerebral aneurysms.