Arteriovenous Malformation

Causes of Arteriovenous Malformation

Experts are not sure exactly why AVMs happen in most cases. They are usually present at birth, but doctors believe that some people can develop AVMs later in life.

This condition seems to be inherited (passed down through a family) in rare cases, but it may also happen by chance. Males have AVMs more often than females.

Symptoms of AVM

Some of the symptoms of AVM are:

• Headaches that affect one particular area of the head
• Weakness or numbness, usually in the same part of the body
• Seizures
• Ringing in the ears
• A feeling of dizziness or being off balance

When any of these symptoms are severe, it is a medical emergency and could be a sign of bleeding in the brain. Note that seizures are a medical emergency in all cases unless your child has a known seizure condition.

In some rare cases, an AVM in the brain may also result in the child suddenly being unable to speak or understand other people when they speak. This is also an emergency.

Diagnosing AVM

If your child's doctor suspects an AVM in the brain, they will likely order imaging tests to confirm it. These may include:

• MRI (magnetic resonance imaging) scan — An MRI machine takes detailed pictures using magnets and radio waves
• MRA (magnetic resonance angiography) scan — A special dye is injected into a vein so a machine can take images of the veins and arteries inside the brain
• CT (computed tomography) scan — Similar to an X-ray, but pictures are taken in "slices" of the head and put together to make a three-dimensional image with a lot of detail
• EEG (electroencephalogram) — Brain waves are measured by attaching electrodes to the scalp with stickers

None of these tests are painful, though angiography requires a needle stick. Depending on your child's age, they may need to be sedated or put to sleep for some of these tests.

AVMs can be present for years without causing any problems. However, if an AVM is causing symptoms, it needs to be corrected. If you discover an AVM before it begins causing symptoms, it is still best to get it treated, as there is always a chance that it will burst and cause brain damage.

Your child's treatment options may depend on where the AVM is located in the brain. Some treatment options for brain AVMs are as follows:

Embolization

In this procedure, a tube is placed into an artery in the groin and pushed through the artery all the way to the brain. The blood flow into the AVM is reduced or stopped by injecting a substance like glue into that part of the artery.

Embolization is preferred because it does not involve brain surgery, but not all AVMs can be treated this way.

Stereotactic Radiosurgery

This treatment uses carefully measured radiation beams aimed at the AVM. The radiation damages the vessels so that they eventually close themselves off.

This treatment is useful for small AVMs or those that are difficult to reach with open surgery or with an embolization. This type of treatment reduces the risk of bleeding in the brain.

Surgical Removal

Some AVMs can only be treated by open surgery. Open surgery involves cutting a hole in the skull close to the AVM. Using a microscope and special instruments, the surgeon will cut and close the veins near the AVM, removing them from the brain. They will then repair the skull and close the skin.