A brain arteriovenous malformation (AVM) is a combination of abnormal blood vessels connecting arteries and veins in the brain. While the arteries are responsible for taking oxygen-rich blood from the heart to the brain and the veins are responsible for carrying oxygen-depleted blood back to the lungs and heart, disruption of this process can happen and thus, a brain AVM occurs. This condition is rare and affects less than 1 percent of the population. Once diagnosed, a brain AVM can often be treated successfully to prevent complications, such as brain damage or stroke.


A brain arteriovenous malformation may not show any signs or symptoms until the AVM ruptures, resulting in bleeding in the brain (hemorrhage). In about half of all brain AVMs, hemorrhage is the first sign.

Individuals who do not experience hemorrhaging usually experience the following symptoms caused by a brain AVM:

  • Seizures
  • Headaches
  • Sharp pain in one area of the head
  • Muscle weakness or number in one part of the body

More serious signs and symptoms may occur depending on the severity of an individual’s condition and the location of the AVM. These symptoms may include:

  • Throbbing headache
  • Weakness and numbness
  • Loss of muscle function
  • Impaired vision
  • Speech impairment
  • Confusion or inability to comprehend
  • Severe unsteadiness


The cause of brain AVM is unknown, however researchers believe most brain AVMs occur due to abnormal development of blood vessels during fetal development.

Risk Factors

Any individual may be born with a brain AVM; however, some factors may present a higher risk such as:

  • Being a male: AVMs are more common in men
  • Family history of AVMs: Possibility of inheriting vascular malformations such as AVMs is greater


Complications of a brain AVM may include:

  • Reduced oxygen to brain tissue: Without enough oxygen, brain tissues weaken or may die off completely. This results in stroke-like symptoms, such as speech impairment, weakness, numbness, blindness, or severe unsteadiness.
  • Thin or weak blood vessels: a bulge in a blood vessel wall may occur when pressure is put on it, thus causing a ruptured brain AVM.
  • Brain damage: Blockage of protective fluids to the brain.
  • Bleeding in the brain (hemorrhage)