Arteriovenous Malformations

Arteriovenous malformations, or AVMs, are tangled arteries and veins in the brain that disrupt blood flow.

Also called a cerebral or brain arteriovenous malformation, an AVM is a circulatory disorder that interferes with the connection between arteries and veins in your brain. Normal arteries deliver oxygen-rich blood from your heart to your brain, while normal veins carry blood that has less oxygen back from your brain to your heart. If you develop an AVM, tangled blood vessels in your brain may abnormally redirect blood from the arteries directly to the veins, bypassing normal vessels between them.

The American Stroke Association (ASA) estimates that brain AVMs occur in fewer than 1 percent of Americans. An estimated one in 200 to 500 people may have an AVM, and they're more common in men than women.

Experts don't know what causes AVMs. They are often congenital, or present at birth, but they typically aren't inherited and can occur at any age. Some people with an AVM also have brain aneurysms.

Brain AVMs vary in size and may be located anywhere in or on the brain. The resulting pressure can damage blood vessels, and an AVM may break or rupture. When this happens, blood can leak into your brain or surrounding tissues, restricting blood flow to your brain and causing serious complications, including stroke.

Symptoms and Diagnosis

Symptoms of a bleeding AVM may include:

  • Difficulty seeing or speaking.
  • Loss of memory.
  • Stroke symptoms, such as a drooping face, crooked smile, or arm or leg weakness.
  • Confusion.
  • Ear noise or buzzing (pulsatile tinnitus).
  • Headache that may seem like a migraine.
  • Difficulty walking.
  • Seizures.
  • Muscle weakness or numbness anywhere in your body or face.
  • Dizziness.

A bleeding AVM is a medical emergency. Call 911 if you experience AVM symptoms.

Diagnostic Tests for AVMs

Varied types of brain diagnostic tests help identify the size, type and location of an AVM, and other information. Tests that may be used include:

  • CT scan 
  • MRI  
  • Cerebral angiogram (arteriogram)
  • EEG (electroencephalogram)


If an AVM is detected on an X-ray, CT scan or other imaging test, your team of neurology and vascular specialists at El Camino Health will work together with each other and with you to determine your best treatment. Each expert has advanced skills and experience in treating complex brain vascular abnormalities.

If you aren't experiencing any symptoms, your doctor will talk with you about:

  • The risk that your AVM will break or bleed, risking brain damage if it's untreated.
  • Potential risks and complications of surgical or other treatments.

Treatments are focused on preventing dangerous AVM bleeding and removing the AVM if possible. If there has been brain damage, El Camino Health's comprehensive rehabilitation services can help.

Treatment Options

Your doctor will discuss your best options and may suggest one or a combination of treatments, such as:

  • Medical management – May be recommended if you have no symptoms or if an AVM is in an area of your brain that's difficult to treat. Medically managing an AVM includes regular checkups with a neurologist or neurosurgeon. It may include medication to lower your blood pressure or manage other risk factors, and avoiding medications, such as blood thinners, that can increase your risk. Doctors will closely monitor your blood pressure and other indicators.
  • Surgery – Sometimes chosen if an AVM has bled or is in a more easily reached part of the brain. During this procedure, your neurosurgeon opens your skull to access your brain and remove the AVM.  
  • Neurointervention (endovascular surgery) – Involves inserting a thin tube, called a catheter, that your specialist will guide from a blood vessel in your groin to the blood vessels in your brain to reach the AVM. Surgeons may insert tiny coils or other glue-like materials through the catheter and into the abnormal blood vessels to stop blood flow and lower the risk of bleeding. This is often performed along with either open surgery or radiosurgery.
  • Stereotactic radiosurgery – Sometimes used for AVMs deep in the brain that are difficult to reach through traditional surgery. An angiogram may be done to locate and identify the AVM. Using advanced stereotactic radiosurgery technology such as Varian radiotherapy, specialists can direct powerful, precisely focused radiation energy to the AVM's location to shrink or scar the AVM and prevent bleeding. 
  • Other medications as needed – Anti-convulsive medications or other drugs may be prescribed if seizures or other complications occur. 

Ask your doctor about the relative risks and benefits of treatment or management if an AVM is detected. You can be proactive by scheduling regular checkups, staying informed and making healthful lifestyle choices.

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