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What is Arteriovenous Malformation (AVM)?

An arteriovenous malformation (AVM) is an abnormal connection between arteries and veins, resulting in a “tangle” of blood vessels in the brain and spinal canal. In normal circulation, blood flows from arteries to capillaries and then to veins, taking blood from high pressure to low pressure gradually. However, in AVMs, blood flows directly from arteries to veins through an abnormal passageway called a fistula, rather than through capillaries. This leads to downstream effects, including increased flow and pressure. Over time, the vessels fatigue, leading to rupture. The injury can endanger physical and neurological functions -- such as sight, sensation, critical thinking and movement -- that are associated with that area of the brain. A rupture also can be fatal.

Some brain AVMs come to attention in ways other than bleeding, such as seizure. The majority of patients are between 20 to 50 years of age when a brain AVM comes to be diagnosed. However, brain AVMs can affect people of any age.

Nirav J. Patel, MD, Neurosurgeon at Brigham and Women’s Hospital, discusses the treatment and approach to care for an Arteriovenous Malformation (AVM) diagnosis.

What are the risk factors for Arteriovenous Malformation (AVM)?

This tangle of arteries and veins usually develops before birth or shortly after. Occasionally, an AVM forms later in life, though it is unclear if the risk for an AVM is passed down through families genetically. For someone with an AVM, an increase in blood pressure is a risk factor for rupture.

What are the symptoms of Arteriovenous Malformation (AVM), and how is Arteriovenous Malformation diagnosed?

Most people who have an AVM may be unaware of the abnormality and experience no symptoms. Some brain AVMs present with symptoms including:

  • Seizures, new onset
  • Muscle weakness or paralysis
  • Loss of coordination
  • Difficulties carrying out organizational tasks
  • Dizziness
  • Headaches
  • Visual Disturbances
  • Language Problems
  • Abnormal sensations (numbness, tingling or spontaneous pain)
  • Memory deficits
  • Mental confusion
  • Hallucinations
  • Dementia

Women with AVMs can sometimes develop symptoms during pregnancy.

  • Computed Tomography Angiography (CTA) uses a series of x-rays to create a cross-sectional image of the brain. To better visualize an AVM, contrast dye is injected while the CT scanner takes pictures. This enables radiologists to map the AVM in greater detail and produce a 3D composite image of the AVM.
  • Magnetic Resonance Angiography (MRA) is a type of MRI scan that uses a powerful magnet to create highly detailed images of your brain without using x-ray radiation.
  • Digital Subtraction Angiography (DSA), also called Cerebral or Spinal Angiography depending on the region being imaged, is the most comprehensive procedure offered by our neuroradiology team to help characterize an AVM. In this exam, an endovascular neurosurgeon inserts a catheter into an artery near the groin and guides it to the head/neck or spine region. Using contrast dye and fluoroscopy (a type of x-ray) images are taken of the dye traveling through arteries and veins in the brain or spine. This provides an extremely detailed 3D map of the AVM, highlighting its location and characteristics. Knowing how blood flows within the AVM is very important to decision-making and planning.

What are the treatment options for Arteriovenous Malformation (AVM)?

A team of specialists at Brigham and Women’s Hospital Center for Cerebrovascular Diseases (including neurosurgeons, endovascular surgeons, neurologists and radiation oncologists) collaborate to determine the best treatment for each AVM. The best treatment depends on the AVM’s location and anatomy and the decision is centered around the patient, to achieve a cure with the least risk.

  • Embolization involves injecting a material into the blood vessels that blocks blood flow to the AVM.
  • Surgery can then be used to remove the AVM.
  • Some AVMs are best treated with radiosurgery, which directs highly focused beams at the AVM. It can take time for the AVM to completely disappear after radiosurgery.

For more detailed information, see more information on treatment of Arteriovenous Malformations.

Contact the Center for Cerebrovascular Diseases

To schedule an appointment with a physician in the AVM Program at the Center for Cerebrovascular Diseases, please contact our Patient Coordinator at: (617) 732-6600. We see new patients with AVMs as soon as the next business day.

If you are a physician seeking to refer a patient to the Center for Cerebrovascular Diseases, please call (617) 732-6600 or you can access our physicians’ office phone numbers. To contact one of our physicians with a question, patient referral or second opinion, you may also email:

Arteriovenous Malformation (AVM) in the News

After Others Deemed Her Case Inoperable, Brigham Neurosurgery Team Cures a Mom's Rare, Deadly Brain Disorder
Brigham Bulletin | May 5, 2022

On the Road to Recovery
Whitman-Hanson Express | February 18, 2021

Carrying Hope: Determination Takes Yoga Teacher Over the Boston Marathon Finish Line
Health Hub Blog | August 9, 2019


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