Arteriovenous Malformations (AVM)

What is an Arteriovenous Malformation?

An arteriovenous malformation, or AVM, is a knot of abnormal and poorly formed blood vessels, like arteries and veins.

They have a high tendency to bleed, so while AVMs can form in any part of the body, the potential for bleeding makes AVMs that form in the brain potentially very dangerous. The brain and its arteries are formed at the same time during embryological development; therefore, abnormal formations of blood vessels are usually associated with abnormal brain tissues. As a result, AVMs are also associated with abnormalities of the brain tissues.

The size and location of AVMs vary in the brain. AVMS affect less than one percent of the population. Although AVMs are believed to develop before or shortly after birth, their symptoms may appear at any age.

Causes of Arteriovenous Malformations

The causes of arteriovenous malformations are not yet fully known.

Arteries are connected to veins by structures called capillaries. AVMs are formed when arteries connect to veins without the presence of capillaries.

AVMs can rupture from pressure, which can damage the tissues of the blood vessels. This results in blood escaping from the vessels and leaking into the brain and surrounding tissues. The flow of blood to the brain is reduced as a result of this bleeding.

Symptoms of Arteriovenous Malformations

The symptoms depend on the size and location of the arteriovenous malformation. An AVM may not exhibit any symptoms in some cases.

Possible symptoms include:

  • Seizures: AVMs can affect the electrical activity in the brain. This may result in seizures.
  • Headaches: Headaches may occur due to high flow of blood through the AVM. Migraines or headaches similar to migraine may occur. They might be mild or severe.
  • Stroke-like symptoms: AVMs may deprive the brain of oxygen and essential nutrients, leading to stroke-like symptoms. These may include partial paralysis of one side of body, weakness in one side of body, loss of sensation or numbness, problems with vision, hearing, and balance. Loss of memory and changes in personality might also occur.