A cerebral arteriovenous malformation (AVM) is an abnormal connection between the arteries and veins in the brain that usually forms before birth.
The cause of cerebral AVM is unknown. An AVM occurs when arteries in the brain connect directly to nearby veins without having the normal small vessels (capillaries) between them.
AVMs vary in size and location in the brain.
An AVM rupture occurs because of pressure and damage to the blood vessel. This allows blood to leak (hemorrhage) into the brain or surrounding tissues and reduces blood flow to the brain.
Cerebral AVMs are rare. Although the condition is present at birth, symptoms may occur at any age. Ruptures happen most often in people ages 15 to 20. It can also occur later in life. Some people with an AVM also have brain aneurysms.
In about one half of people with AVMs, the first symptoms are those of a stroke caused by bleeding in the brain.
Symptoms of an AVM that is bleeding are:
Symptoms due to pressure on one area of the brain include:
Your health care provider will perform a physical examination. You'll be asked about your symptoms, with a focus on your nervous system problems. Tests that may be used to diagnose an AVM include:
Finding the best treatment for an AVM that is found on an imaging test, but is not causing any symptoms, can be difficult. Your provider will discuss with you:
Your provider may discuss different factors that may increase your risk of bleeding, including:
A bleeding AVM is a medical emergency. The goal of treatment is to prevent further complications by controlling the 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. The surgery is done through an opening made in the skull.
Embolization (endovascular treatment):
Medicines to stop seizures are prescribed if needed.
Some people, whose first symptom is excessive brain bleeding, will die. Others may have permanent seizures and brain and nervous system 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 in rare cases, cause symptoms.
Complications may include:
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 right away if you have a first-time seizure, because AVM may be the cause of seizures.
Reviewed By: Alireza Minagar, MD, MBA, Professor, Department of Neurology, LSU Health Sciences Center, Shreveport, LA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.