Arteriovenous malformations

Overview

Arteriovenous malformations (AVMs) are abnormal tangles of arteries and veins that grow in the brain. The malformation can form wherever there are arteries or veins in the brain or spinal cord and they are the leading cause of hemorrhagic strokes in children and adolescents.

AVMs, which belong to a group of disorders known as vascular malformations, typically develop in the womb or soon after birth. Although not completely understood, they may be linked to genetic mutations.

Arteries carry oxygen-rich blood away from the heart to the body's cells and veins return oxygen-depleted blood to the lungs and heart. When AVMs disrupt this process, they can reduce the amount of oxygen received by brain tissues. This can lead to the compression of parts of the brain or spinal cord. The most severe risk of AVM is bleeding, called a hemorrhage, in the brain, which can lead to a debilitating or fatal stroke.

AVMs of the brain or spinal cord affect about 300,000 Americans. Occurring equally in males and females from all ethnic and racial backgrounds, symptoms are more common in children over 9-years-old than those who are younger.

AVMs are treated at the UCSF Pediatric Stroke and Cerebrovascular Disease Center, the only comprehensive cerebrovascular disease center for children in the country staffed by the world's leading experts in pediatric stroke and cerebrovascular disease.

Signs & symptoms

Children who are born with arteriovenous malformations (AVMs) may not experience symptoms for many years. In fact, symptoms may occur anywhere between age 10 and 40.

Symptoms, however, can occur at any age, as in the most severe forms of the disease, called a Vein of Galen Malformation. This condition may cause symptoms at birth or very soon after. Symptoms may include swelling of the brain, seizures, failure to thrive, congestive heart failure and swollen veins.

Each child may experience symptoms differently, depending on the location of the AVM. Some of the most common symptoms include:

• Abnormal sensations, such as numbness, tingling or spontaneous pain
• Dizziness
• Headache, varying in severity, duration and intensity
• Loss of coordination, known as ataxia
• Muscle weakness or paralysis in one part of the body
• Seizures, which may be partial or total and may cause a loss of movement and consciousness as well as convulsions
• Stroke
• Visual disturbances, such as partial loss of eye sight or eye moment control

Diagnosis

The following tests may be used to determine if your child has an arteriovenous malformation (AVM) as well as to help identify its size, location and blood-flow pattern.

• Angiogram — This is an important test in the diagnosis of AVM and involves a special X-ray exam that enables a radiologist, a doctor who specializes in understanding and interpreting X-rays, to study your child's blood vessels. The radiologist will insert a small tube, called a catheter, into the blood vessel and then inject a special dye that makes the vessels visible on the X-rays. This will allow the radiologist to observe how the blood travels through the blood vessels of the brain. The procedure takes about one hour.
• Computed Tomography (CT) — A CT scan is a method of body imaging in which a thin X-ray beam rotates around the patient. It can be used to detect the presence of blood in the brain.
• Magnetic Resonance Imaging (MRI) — An MRI scan can detect if there is blood in the brain. It is a non-invasive procedure that uses powerful magnets and radio waves to construct pictures of the body.

Treatment

Our experts — among the best in the world — will work with you and your family to develop the best possible treatment plan for your child. This team includes a neurologist, neurosurgeon, neurointerventional radiologist and radiation oncologist.

Because arteriovenous malformations (AVMs) are one of the leading causes of debilitating hemorrhagic strokes in young people, the goal of treatment is to reduce the risk of stroke. Today, there are many safe and highly effective therapies. These include surgery, radiation therapy, embolization and radiosurgery using a machine called a Gamma Knife.

• Surgery — In many cases, surgery may be recommended to completely remove your child’s AVM. In addition to conventional brain surgery, advanced, minimally invasive surgical techniques are available.
• Gamma Knife — The Gamma Knife is an advanced radiosurgery treatment for abnormal blood vessel formations, is often recommended for children with complex, deep seated or brain stem AVMs. Despite its name, it isn't a knife at all. It delivers a single, very finely focused, high dose of radiation precisely to its target, while causing little or no damage to surrounding tissue. The Gamma Knife may be used in combination with other treatments, such as surgery, or by itself as the primary therapy.
• Embolization — This technique is used to reduce blood flow to the AVM by obstructing surrounding blood vessels. During this procedure, the AVM is filled with specially designed coils, glues or spheres, which plug its vessels. As a result, blood flow is decreased, making the AVM more manageable for future procedures such as surgery.