Arteriovenous malformations (AVMs) are tangles of blood vessels that cause the atypical flow of blood between your veins and arteries. If they rupture, they may be life threatening.

AVMs usually develop in the womb or shortly after birth.

They often don’t cause any symptoms and may be found incidentally during testing for another health condition.

They commonly develop in the brain or spinal cord. A rupture of an AVM in these parts of your body can cause life threatening bleeding or other serious complications like seizures or a stroke.

If your doctor thinks your AVM is at a high risk of bleeding, they might recommend surgery. Low risk AVMs might not need treatment.

Read on to learn more about AVMs including symptoms, risk factors, and treatment options.

How common are AVMs?

Experts estimate that AVMs occur in about 1 in 70,000–89,000 people per year. They believe AVMs in the brain occur in 1 in 75,000 people, but this may be an underestimation since many people might never have symptoms.

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Arteriovenous malformations most commonly occur in your brain and spinal cord. Most of the time, AVMs don’t cause any noticeable symptoms unless they rupture.

Healthcare professionals often discover them incidentally during treatment or imaging for an unrelated condition or during an autopsy after death.

AVMs are most commonly discovered in adults older than 20 since children rarely have noticeable signs or symptoms.

The cause of an AVM is often unknown but they usually occur before birth. Experts attribute some AVMs to genetic syndromes that run through families, but some develop without a family history.

Genetic syndromes linked to AVM include:

Some AVMs develop later in life due to injury to the central nervous system.

A ruptured AVM can cause many different symptoms depending on where in your body it occurs. Some of the potential symptoms if it occurs in your brain or spinal cord include:

AVMs can bleed and cause serious complications. Some complications like stroke can be life threatening. Other serious complications can include:

  • brain abscess
  • low oxygen levels (hypoxemia)
  • life threatening bleeding
  • developmental delays in children
  • the buildup of fluid in the brain (hydrocephalus)

Many people who have AVM don’t have any symptoms but it’s important to get immediate emergency attention if you or somebody you’re with develops stroke or other concerning symptoms.

Medical emergency

It’s critical to call emergency medical services immediately if you or somebody you’re with has sudden:

  • numbness or weakness in your face, arm, or legs
  • confusion, trouble speaking, or trouble understanding speech
  • trouble seeing in one or both eyes
  • trouble walking
  • dizziness
  • balance problems
  • severe headache with no known cause

Learn more about stroke symptoms.

One of the most distinctive signs of an AVM is a bruit, a type of whooshing sound caused by rapid blood flow through your arteries and veins that your doctor may be able to hear with a stethoscope.

Healthcare professionals often find AVMs incidentally during imaging for unrelated conditions. An ultrasound is often the first test that doctors order to investigate an AVM.

Other imaging tests that you might receive include:

If your doctor thinks your AVM is at a low risk of rupturing, you might not need any specific treatment. If they do think your AVM might rupture, your doctor will likely recommend surgery.

Surgical treatment options include:

  • Conventional surgery: Conventional surgery involves entering your brain or spinal cord and removing the AVM while causing as little damage as possible to healthy tissue. It may be used for AVMs in the outermost layers of your brain or spinal cord.
  • Endovascular embolization: Endovascular embolization involves inserting a catheter through an artery until the tip reaches your AVM. Your surgeon will then inject a substance or insert a coil or balloon to create a clot.
  • Radiosurgery: Radiosurgery involves using a beam of highly focused radiation to close the AVM.

Learn more about arteriovenous malformation surgery.

Most people who have an AVM don’t develop problems either with or without treatment.

Experts estimate only about 12% of AVMs in the brain become symptomatic. The rate of people dying who have a rupture is about 10–15% and the morbidity rate for people who have bleeding is about 30–50%.

The success rate of surgical treatment as the first-line treatment of spinal AVM is around 98%.

Here are some frequently asked questions people have about AVMs.

How serious is an arteriovenous malformation?

AVMs that form in your brain or spinal cord can be very serious. The risk of death is very high if the AVM ruptures, although the majority of people never develop problems.

Can AVM be cured?

Some surgeries can result in complete removal or embolization of the AVM, which is considered a cure. Surgery can also drastically reduce the risk of your AVM bleeding.

What are the chances of surviving an AVM?

The chances of surviving an AVM that ruptures in your brain is about 85–90%. The majority of AVMs don’t rupture but your doctor may recommend preventive surgery if they think there’s a high risk of your AVM rupturing in the future.

AVMs are atypical connections between the veins and arteries that usually form before birth. They often don’t cause any symptoms but can cause serious bleeding and life threatening complications if they rupture.

A ruptured AVM comes with a high risk of death if it occurs in your brain. If your doctor thinks your AVM is at a high risk of rupturing, they may recommend surgery to keep this from happening.