Arteriovenous Malformations

An arteriovenous malformation (AVM) is a thick bundle of vessels in the brain. In the normal brain, the veins and arteries are separate vessels which circulate blood throughout the brain tissue. The arteries carry blood rich with oxygen from the lungs, and the veins carry blood back to the heart for recirculation. Each vessel is normally separate and travels in its own pathway. In an AVM, the blood vessels are tangled together and do not travel in their own path. Much like a small ball of string, the vessels are wrapped around each other.

Signs and symptoms

An AVM is something a person is born with and usually is not detected until the age of 20 to 50 years. Symptoms begin as the person ages and the vessels become thickened. Eventually the vessels may leak or even rupture. The symptoms the person experiences are due to this leakage of blood into the surrounding brain tissue. The most common symptoms of AVM are:

Headache and/or seizures. Often the headache is due to a rupture of the vessels and may cause an intraparenchymal, subarachnoid or intraventricular hemmorhage. The headache is sudden and severe and may be accompanied by nausea and vomiting.
The person may experience dizziness and may even lose consciousness.
A seizure in someone who has never had a seizure before is another symptom of AVM.

If any of these symptoms occur, it is best to seek medical attention immediately.

Diagnostic tests

If your health-care provider suspects you have an AVM, the following tests may be performed:

CT scan

A special X-ray to look for the presence of blood in the brain.

MRI

A special magnetic resonance scan to look for the presence of blood in the brain.

Angiogram

This is an important test in the diagnosis of an AVM. The test is performed in a special X-ray room and takes approximately one hour. An angiogram involves injection of a contrast dye through a special tube and watching how that dye circulates through the blood vessels of the brain. A radiologist will explain the test in further detail. If you are allergic to dye or have had a reaction to dye in the past, it is important to tell the radiologist.

Treatment

While in the hospital, the patient likely will be in the intensive care unit. Specially trained nurses will be checking the blood pressure, heart rate and breathing frequently. The patient will also be awakened about every hour to check the pupils, test the arm and leg strength and ask questions to test thinking. The patient may not be able to eat at first, so an intravenous line will be inserted into a vein to give plenty of fluid. Medications for pain, sedation and a stool softener likely will be given. It is important to get plenty of rest, so the patient may be in a darkened room and should try to keep as quiet and comfortable as possible.

Treatment of AVM may involve surgery to remove the bundle of vessels. The surgery often is postponed until the patient is stable and able to tolerate a major surgical procedure. The neurosurgeon will discuss the surgery in detail.

Questions you may want to ask

How long will the surgery take?
What is the recovery time after surgery?
Is there a need for rehabilitation after surgery?
What is the chance of having seizures after surgery?
Is there a need for any additional surgery?

Another treatment option is called radiosurgery. This treatment involves the use of high dose radiation aimed at the bundle of vessels, which spares the surrounding normal tissue. There is no hair loss or skin change associated with radiosurgery, as there may be with conventional radiation.

Reducing the risk

Although there is no way of preventing an AVM, it is important to keep healthy. The following are some suggestions to maintain healthy circulation:

Stop or avoid smoking.
Keep your weight within normal limits for your age and height.
Keep your blood pressure under control.
Reduce stress.
Establish a routine exercise program (check with a health-care provider before beginning an exercise program).
Avoid use of cocaine.