Arteriovenous Malformation (AVM)

You have an arteriovenous malformation (AVM). An AVM is an abnormal tangle of blood vessels in the brain. Some AVMs never burst (rupture). But there are factors that can lead to rupture. Some factors are known, such as an increase in blood pressure. And some factors are not known. If you have an AVM, you were likely born with it. But most people don't know they have one until a problem happens. Signs of an AVM include bad headaches, sudden or progressive paralysis or loss of sensation, blurred or double vision, and jerking movements that are out of your control (seizures).

Side view of head and brain.

Closeup view of arteriovenous malformation (AVM) in the brain.

Blood vessels carry blood throughout the brain.

Pressure builds when blood tries to flow through tangled vessels.

Understanding an AVM

The brain controls the body. You can move and feel because of the brain. And it is the brain that makes you able to think, show emotions, remember, and make judgments. An AVM can damage the brain and put the rest of the body in danger.

Inside the skull

Under the scalp and the skull, a tough membrane (called the dura) surrounds the brain. Beneath the dura, cerebrospinal fluid (CSF) cushions the brain. Blood vessels carry nutrients and oxygen-rich blood throughout the brain.

A problem with blood flow

An AVM is a tangle of blood vessels. It can cause pressure to build up in the blood vessel and prevent normal blood flow. If the pressure becomes too great or the wall of the AVM vessel weakens a blood vessel can burst and blood can leak or spurt into the brain. This can damage parts of the brain that control vital body functions, such as sight, sensation, language, critical thinking, and movements. In some cases, problems caused by an AVM can even lead to death. The high blood flow in an AVM can also shunt the oxygen from the arteries directly to the veins, bypassing the brain capillaries. This shunting can lead to strokes. But an AVM can be treated.