A cerebral arteriovenous malformation is an abnormal connection between the arteries and veins in the brain that usually forms before birth.
AVM - cerebral
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.
In about half of patiens with AVMs, the first symptoms are those of a stroke caused by bleeding into the brain.
Symptoms of an AVM that has not bled include:
A complete physical examination and neurologic examination are needed, but they may be completely normal.
Tests that may be used to diagnose an AVM include:
Finding the best treatment for an AVM that is found on an x-ray or other imaging tests but is not causing any symptoms can be difficult. Your doctor will discuss with you:
The long-term risk of bleeding is about 2 to 3% every year. Your doctor may discuss different factors that may increase the risk, including:
A bleeding AVM is a medical emergency. The goal of treatment is to prevent further complications by controlling bleeding and seizures and, if possible, removing the AVM.
Three surgical treatments are available. Some treatments are used together.
Open brain surgery -- removes the abnormal connection through an opening made in the skull. It must be done by a highly skilled surgeon.
Embolization (endovascular treatment):
Stereotactic radiosurgery is another alternative.
Anticonvulsant medications, such as phenytoin, are usually prescribed if seizures occur.
About 10% of cases in which excess bleeding (hemorrhage) is the first symptom are deadly. Some patients may have permanent seizures and brain and nervous system (neurological) problems.
AVMs that do not cause symptoms by the time people reach their late 40s or early 50s are more likely to remain stable and rarely cause symptoms.
Possible complications of open brain surgery include:
Go to the emergency room or call the local emergency number (such as 911) if you have:
Also seek medical attention if you have a first-time seizure, because AVM may be the cause of seizures.
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Zivin JA. Hemorrhagic cerebrovascular disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 237:chap 432.
Brown RD Jr. Unruptured brain AVMs: To treat or not to treat. Lancet Neurol. 2008;7:195-196.