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Number of people in the U.S. who have an arteriovenous malformation in the brain.*
*Source: The Aneurysm and AVM Foundation

Arteriovenous Malformation Overview

An  arteriovenous malformation (AVM)  is a defect in the circulatory (blood flow) system characterized by an abnormal connection between the arteries and veins. AVMs are made of tangles of arteries and veins and typically form during fetal development or soon after birth.

Although arteriovenous malformations can develop in many different sites, those located in the brain or spinal cord (which make up the central nervous system) can have profound effects on the body. These are known as neurological AVMs and can occur anywhere within the brain or the brain coverings.

The biggest risk with an AVM is bleeding—between two and four percent of all AVMs hemorrhage. If an AVM bleeds it can affect a number of normal body functions depending on the location and extent of the brain injury.

If they are not treated AVMs can rupture, causing brain bleeding, a stroke or permanent brain damage. The effects depend on where the AVM is located.

Normally, arteries carry oxygen-containing blood from the heart to the brain and veins carry blood (with less oxygen) away from the brain and back to the heart. When an AVM occurs, the tangled blood vessels divert blood from the arteries directly to the veins. The abnormal/weak blood vessels dilate over time and eventually may burst from the high pressure of blood flow from the arteries. This causes bleeding into the brain.

There are various types of brain AVM. The most common is known as a true arteriovenous malformation. It consists of a tangle of abnormal vessels connecting arteries and veins with no normal interning brain tissue.

WellStar neurologists and neurosurgeons offer expert, experienced treatment for patients with arteriovenous malformations. They work closely with other specialists including vascular surgeons to assess and recommend a treatment program. Each patient’s condition is unique and your doctor will discuss the specific symptoms and outlook with you.


In some patients arteriovenous malformations do not cause symptoms and are only detected incidentally, for example in the course of treatment for another problem. But about 12 percent of people with AVMs will experience symptoms, which can vary considerably in severity.

The most common and potentially severe symptom is brain (intercranial) hemorrhage, which can result in a  subarachnoid  hemorrhage or intracerebral hemorrhage. If you believe you or someone is experiencing a brain hemorrhage seek immediate medical attention.

Other symptoms include:

  • Seizures
  • Muscle weakness or paralysis
  • Coordination and balance problems (ataxia)
  • Difficulties performing organizational tasks
  • Pain or unusual sensations (tingling or numbness) throughout the body
  • Dizziness
  • Headache
  • Vision problems

Risk Factors

There are two primary known risk factors for arteriovenous malformation

  • Congenital (from birth) genetic defects that can be passed on in families
  • A history of unexplained, recurrent bleeding