Arteriovenous Malformation (AVM)

An arteriovenous malformation (AVM) is a tangled, enlarged mass of blood vessels that occurs due to abnormal connections between arteries and veins. AVMs don’t always cause symptoms, but they may bleed or rupture and can lead to stroke.

AVMs are rare but can affect men and women of all races. They are most common in the brain and spine but can be found anywhere in the body.

At UPMC, our vascular surgeons are experts in treating AVMs. We diagnose and treat AVMs in all areas of the body using medicine, embolization, radiosurgery, or open surgery.

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On this page

• What Is AVM?
• What Are the Symptoms of AVM?
• How Do You Diagnose AVM?
• How Do You Treat AVM?

What Is AVM?

An arteriovenous malformation (AVM) is a tangled, enlarged mass of blood vessels that happens because of abnormal connections between arteries and veins. AVMs don’t always cause symptoms but may bleed or rupture and can lead to stroke.

Arteries carry blood away from your heart, bringing oxygen and other nutrients to your organs and tissues. Blood then flows through very small vessels called capillaries into your veins, which bring the blood back to your heart.

An arteriovenous malformation (AVM) occurs when arteries and veins connect directly to each other rather than through capillaries. This creates a tangled, enlarged mass of blood vessels and abnormal blood flow. AVMs are most common in the brain and spine but can happen anywhere in the body.

The greatest risk of an AVM rupture is bleeding, which may be life-threatening. Cerebral (brain) AVMs can lead to stroke, which may cause permanent disability or death.

How common is AVM?

AVMs are rare but can affect men and women of all races. AVMs are often present at birth but are not inherited (passed down in families).

What are the types of AVM?

There are two types of AVMs:

• Brain arteriovenous malformations — form in the brain, brainstem, and spinal cord, inside the brain tissue, or on the surface of the brain.
• Peripheral arteriovenous malformations — can form anywhere in your body.

What causes AVM?

The cause of AVM is unknown.

What are AVM risk factors and complications?

AVM risk factors

Risk factors for AVMs and bleeding include:

• Gender – Men are more likely to be born with AVMs.
• Family history – Though rare, AVMs may run in families; however, it is unknown if there's a genetic risk factor.
• Hereditary conditions – Certain medical conditions, such as hereditary hemorrhagic telangiectasia (HHT), can increase the risk of AVMs.
• Age – Older people are at a higher risk for AVM hemorrhage.
• Previous bleed – A history of a prior bleed is a significant risk factor for AVM hemorrhage.

Complications of AVMs

AVMs can cause a number of complications, including:

• Bleeding – AVMs have a high risk of bleeding, which can cause stroke and be fatal if left untreated.
• Seizures – Seizures are a complication of AVMs.
• Brain or spinal cord compression – Large AVMs can grow up to 2.5 inches, pressing on the brain or spinal cord and causing neurological symptoms.
• Coordination problems – AVMs in the brain can cause loss of coordination.
• Abnormal sensations – AVMs can cause numbness, tingling, or spontaneous pain.
• Cognitive difficulties – AVMs can cause confusion, loss of function, and memory loss.
• Dizziness – AVMs can cause dizziness if they damage the brain stem or cerebellum.

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What Are the Signs and Symptoms of AVM?

Most people with AVMs have no symptoms. In people with symptoms, those symptoms can vary based on the location of the AVM.

Some AVM symptoms may include:

• Headache.
• Numbness or weakness on one side of the body.
• Muscle weakness.
• Vision loss.
• Seizures.
• Pain.
• Problems with speech, vision, or movement.
• Confusion or not being able to understand others.

When should I see a doctor about my AVM symptoms?

You should see a doctor if you have any symptoms of an AVM. If you notice symptoms of a brain AVM, such as seizures, headaches, or symptoms of a stroke, get emergency medical care immediately.

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How Do You Diagnose AVM?

Doctors often diagnose an AVM while performing tests for another condition. Tests may include:

• CT scans – A CT scan is a test that creates images of organs and structures in your body.
• MRI scans – MRI is a diagnostic procedure that combines large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within your body.

If your doctor suspects you have an AVM, he or she may perform an:

• Angiogram – An angiogram uses a catheter and special x-rays to find the location and severity of the AVM.

Is an AVM life-threatening?

The prognosis for an AVM depends on several factors, including whether the AVM is discovered before or after bleeding.

The survival rate of a ruptured AVM is around 90 percent, though you may experience some neurological problems after the rupture.

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How Do You Treat AVM?

Treatment for AVMs varies based on each person’s:

• Overall health.
• Symptoms.
• AVM size and location.

AVM treatments may include:

• Medicine – Helps manage pain and other symptoms, though this does not treat the AVM.
• Endovascular embolization – A catheter-based procedure that safely blocks blood flow, damaging the AVM and causing it to close.
• Radiosurgery – Uses a beam of radiation to damage the AVM and cause it to close.
• Brain surgery – Brain surgery removes the AVM.

All of these treatments, except medication, are long-term or permanent cures for AVM.

By UPMC Editorial Staff. Last reviewed on 2024-10-01.