Brain Arteriovenous Malformations (AVMs)

A brain arteriovenous malformation (AVM) is a rare congenital lesion that forms accidentally in the brain before birth, creating problems with the connections between arteries and veins.


This abnormal tangle of blood vessels reroutes blood from high-flow arteries that carry blood from the heart to the brain into low-flow, thin-walled veins bringing blood back to the heart. This disrupts blood flow and the circulation of oxygen in the blood.


The most common sign of a brain AVM is a cerebral hemorrhage or bleeding in the brain. Symptoms of a brain bleed depend on where in the brain it occurs, but can include:

  • Weakness
  • Numbness
  • Trouble speaking
  • Vision difficulty
  • Reduced or loss of consciousness
  • Coma or even death in the most severe cases.

In some cases, brain AVMs can cause seizures with or without bleeding in the brain.


It is very common for AVMs to be diagnosed during a CT or MRI scan being done for unrelated health reasons. Once it has been identified or suspected, a neurosurgeon is consulted and a diagnostic cerebral angiogram performed to better characterize its size, location and anatomy.

Treatment Options

While all brain AVMs require patients consult with a neurosurgeon, not all need to be treated. When treatment is necessary, it typically involves some combination of:

Your neurosurgeon will talk with you about the treatment recommended for your AVM, and together you will decide a course of action.

Ayer Neuroscience Institute