Arteriovenous malformations (AVMs) are tangles of abnormal blood vessels. They can form wherever arteries and veins exist, and can be found anywhere in the body. AVMs of the central nervous system (brain and spinal cord) have the most serious symptoms and complications.

Arteriovenous Malformation in the Brain
AVM brain blood vessels
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The exact cause of AVMs is unknown.

Risk Factors

Factors that may increase your chances of an AVM include:

  • Family history—Some types of arteriovenous malformations are from genetic defects that can be passed on from one generation to the next.
  • Prior head injury
  • Prior surgery or radiation therapy


Many times, symptoms may not be present. In those that have them, symptoms can vary from person to person. Symptoms depend on the size and location of the AVM.

An AVM in the brain may cause:

  • Headaches
  • Seizures
  • Loss of movement on one side of the body
  • Muscle weakness
  • Unable to perform movements, but not due to loss of movement
  • Loss of coordination, especially when walking
  • Sudden, severe back pain
  • Difficulty speaking or understanding language
  • Visual problems
  • Memory loss
  • Difficulty thinking or mental confusion

Serious complications of bleeding can lead to:


You will be asked about your symptoms and medical history. A physical exam will be done. Some AVMs are found during an imaging test for another reason.

Imaging tests are done to evaluate the brain and spinal cord. Contrast material may be used to make structures easier to see. These may include:


You may be referred to a specialist who has experience in treating AVMs. Treatment may in a specialized intensive care unit. The goal of treatment is to destroy or remove the AVM, and prevent further bleeding, which can lead to serious complications.

Treatment options vary depending on whether or not the AVM ruptured. A combination of therapies may be used.


Medications can also be used to treat complications associated with an unruptured AVM. These may include:

  • Pain relievers
  • Anticonvulsants to treat seizures
  • Medications to reduce pressure inside the skull
  • Medications to control high blood pressure
  • Medications to control diabetes
  • Careful use of blood thinners


If the AVM ruptured, surgery may be delayed for 2-6 weeks. The type of surgery will depend on the size and location of the AVM. Surgical procedures include:

  • Microsurgery—An operating microscope is used to surgically remove the AVM through an opening in the skull.
  • Embolization—A catheter is guided through the artery until it reaches the AVM. A substance is injected through the catheter to plug the fistula. This procedure reduces the blood flow to the AVM. Embolization is more common with AVMs that are deeper in the brain.
  • Radiosurgery—A beam of radiation is focused on the AVM. The radiation destroys the walls of the blood vessels that lead to an AVM. Stereotactic radiosurgery (SRS) delivers radiation in a very precise location. It allows for delivery of a higher dose of radiation.


There are no current guidelines to prevent AVMs because the cause is unknown. If AVMs run in your family, talk to your doctor about your options.

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