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 their size and location within the brain. There are often no symptoms until the AVM ruptures. This results in sudden bleeding in the brain (hemorrhagic stroke). In more than half of patients with AVM, hemorrhage is the first symptom. Depending on the location and the severity of the bleed, the hemorrhage can be very disabling or even deadly. Symptoms of an AVM rupture are similar to a stroke, and occur because of a lack of blood flow to the brain. Symptoms may also occur when large AVMs press on the brain tissue, which can cause nerve damage and blood flow problems. Cerebral arteriovenous malformations 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 aged 15 - 20, but can also occur later in life. Some patients with an AVM also have a cerebral aneurysm. | 
General Neurosurgery
