Arteriovenous malformation - cerebral
A cerebral arteriovenous malformation is an abnormal connection between the arteries and veins in the brain that usually forms before birth.
AVM - cerebral
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.
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:
- Ear noise/buzzing (also called pulsatile tinnitus)
- May be in one area (localized) or the entire head
- May resemble a migraine headache in some cases
- Problems walking
- Seizures of all types and severity
- Symptoms caused by pressure on one area of the brain
Signs and tests
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 risk that your AVM will break open (rupture). If this happens, there may be permanent brain damage.
- The risk of any brain damage if you have one of the surgical treatments listed below.
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:
- Current or planned pregnancies
- Features of the AVM on an MRI or CT scan
- Size of the AVM
- Your age
- Your symptoms
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):
- A catheter is guided through a small cut in your groin to an artery and then to the small blood vessels in your brain where the aneurysm is located.
- A glue-like substance is injected into the abnormal vessels to stop blood flow in the AVM and reduce the risk of bleeding. This may be the first choice for some kinds of AVMs, or if surgery cannot be done.
Stereotactic radiosurgery is another alternative.
- This procedure delivers very focused radiation directly to the area of the AVM to cause scarring and shrinkinge.
- It is particularly useful for small AVMs deep in the brain, which are difficult to remove by surgery.
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.
- Brain damage
- Intracerebral hemorrhage
- Language difficulties
- Numbness of any part of the face or body
- Persistent headache
- Subarachnoid hemorrhage
- Vision changes
- Water on the brain (hydrocephalus)
- Weakness in part of the body
Possible complications of open brain surgery include:
- Brain swelling
Calling your health care provider
Go to the emergency room or call the local emergency number (such as 911) if you have:
- Numbness in parts of the body
- Severe headache
- Other symptoms of a ruptured AVM
Also seek medical attention if you have a first-time seizure, because AVM may be the cause of seizures.
Selman WR, Blackham K, Tarr RW, Ratcheson RA. Vascular diseases of the nervous system: Vascular malformations. In: Bradley WG, Daroff RB, Fenichel Gm, Jankovic J, eds. Bradley: Neurology in Clinical Practice. 5th ed. Philadelphia, Pa: Butterworth Heinemann Elsevier; 2008:chap 55D.
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.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.