Brain AVM (arteriovenous malformation)

A brain AVM (arteriovenous malformation) is an abnormal connection between arteries and veins. An AVM is usually congenital, meaning it dates to birth.

An AVM can develop anywhere in your body but occurs most often in the brain or spine. A brain AVM, which appears as a tangle of abnormal arteries and veins, can occur in any part of your brain. The cause isn't clear.

You may not know you have a brain AVM until you experience symptoms, such as headaches or a seizure. In serious cases, the blood vessels rupture, causing bleeding in the brain (hemorrhage). Once diagnosed, a brain AVM can often be treated successfully.

Symptoms Causes Risk factors Complications

A brain AVM (arteriovenous malformation) may not cause any signs or symptoms until the AVM ruptures, resulting in bleeding in the brain (hemorrhage). However, some people with an AVM may have symptoms other than bleeding that are related to the AVM.

An AVM may also be detected on a brain scan performed for reasons unrelated to the AVM.

Symptoms of a brain AVM include:

  • Seizures
  • A whooshing sound (bruit) that can be heard on examination of the skull with a stethoscope or may be audible if you have an AVM
  • Headache
  • Progressive weakness or numbness

Some people may experience more-serious neurological symptoms, depending on the location of the AVM, including:

  • Severe headache
  • Weakness, numbness or paralysis
  • Vision loss
  • Difficulty speaking
  • Inability to understand others
  • Severe unsteadiness

Symptoms may begin at any age, but you're more likely to experience symptoms between ages 10 and 40. Brain AVM can damage brain tissue over time. The effects slowly build up, sometimes causing symptoms in early adulthood.

Once you reach middle age, however, brain AVMs tend to remain stable and are less likely to cause symptoms.

Some pregnant women may have worsened symptoms. However, it's not clear that pregnant women are at greater risk of an AVM bleeding. More research is needed to determine the risk during pregnancy.

When to see a doctor

Seek immediate medical attention if you notice any signs or symptoms of a brain AVM, such as seizures, headaches or other symptoms. A bleeding brain AVM is life-threatening and requires emergency medical attention.

© 1998-2015 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. Terms of use