Arteriovenous
Fistulas

(Dural & Cavernous Carotid)

Symptoms

Symptoms of AVM vary based on where it's located. Often the first signs and symptoms appear after bleeding occurs, and can include:

  • Bleeding

  • Progressive loss of neurological function

  • Headaches

  • Nausea and vomiting

  • Seizures

  • Loss of consciousness

Other possible signs & symptoms include:

  • Weak muscles

  • Paralysis in one part of the body

  • Loss of coordination (ataxia) that can cause problems with gait

  • Problems performing tasks that require planning (apraxia)

  • Weakness in the lower extremities

  • Back pain

  • Dizziness

  • Vision problems, including losing part of your field of vision, loss of control of eye movements, or swelling of part of the optic nerve

  • Problems with speech or understanding language (aphasia)

  • Unusual sensations including numbness, tingling or sudden pain

  • Memory loss or dementia

  • Hallucinations

  • Confusion

Children and teens may have trouble with learning or behavior. One type of AVM called a vein of Galen defect causes symptoms that appear at or shortly after birth. A vein of Galen defect is located deep inside the brain. Signs can include:

  • A buildup of fluid in the brain (hydrocephalus) that causes enlargement of the head

  • Swollen veins on the scalp

  • Seizures

  • Failure to thrive

  • Congestive heart failure

When to See a Doctor

Seek medical attention if you have any of the signs and symptoms of an AVM, such as headaches, dizziness, vision problems, and changes in cognition or neurological function. Many AVMs are currently discovered by "accident," often after a CT scan or an MRI is obtained for reasons not directly related to the AVM.

Causes

AVMs are caused by development of abnormal direct connections between arteries and veins, but experts don't understand why this happens. Certain genetic changes may play a role, but most types are not usually inherited.

Risk Factors

Rarely, having a family history of AVMs may increase your risk. But most types of AVMs are not inherited. Certain hereditary conditions may increase your risk of AVM. These include hereditary hemorrhagic telangiectasia (HHT), also called Osler-Weber-Rendu syndrome.

Complications

The most common complication of an AVM is bleeding. If left unnoticed, the bleeding can cause significant neurological damage. The bleeding can be fatal.

Diagnosis

To diagnose an AVM, your doctor will review your symptoms and perform a physical examination. He or she may listen for a sound called bruit. Bruit is a whooshing sound caused by very rapid blood flow through the arteries and veins of an AVM. It sounds like water rushing through a narrow pipe. Bruit may interfere with hearing or sleep or cause emotional distress. Tests commonly used to help diagnose AVM include:

  • Cerebral angiography. Also called arteriography, this test uses a special dye called a contrast agent injected into an artery. The dye highlights the structure of blood vessels to better show them on X-rays.

  • Computerized tomography (CT). CT scans use X-rays to create images of the head, brain or spinal cord and can help show bleeding.

  • Magnetic resonance imaging (MRI). An MRI uses powerful magnets and radio waves to show detailed images of the tissues. An MRI can pick up on small changes in these tissues.

  • Magnetic resonance angiography (MRA). An MRA captures the pattern and the speed and distance of blood flow through the vascular abnormalities.

  • Transcranial Doppler ultrasound. This type of ultrasound uses high-frequency sound waves to create an image of the blood flow to help diagnose large and medium AVMs, as well as bleeding.

Treatment

Treatment for AVM depends on where the abnormality is found, the symptoms that you have and your overall health. Sometimes, an AVM may be monitored with regular imaging tests to watch for changes or problems. Other AVMs require treatment. Determining whether or not an AVM needs treatment involves factors such as:

  • If the AVM has bled

  • If the AVM is small enough to treat

  • If the location of the AVM is in a part of the brain that can be reached

Medications

Medications can help manage symptoms such as seizures, headaches and back pain.

Surgery

The main treatment for AVM is surgery. Surgery may be recommended if you're at a high risk of bleeding. The surgery may completely remove the AVM. This treatment is usually used when the AVM is small and located in an area where surgeons can remove the AVM with little risk of causing significant damage to the brain tissues.

Endovascular embolization is a type of surgery in which the surgeon threads a catheter through the arteries to the AVM. Then a substance is injected to create an artificial blood clot in the middle of the AVM to temporarily reduce the blood flow. This may also be done before another type of surgery to help reduce the risk of complications.

Sometimes stereotactic radiosurgery is used. This procedure is usually performed on small AVMs that have not ruptured. This uses intense, highly focused beams of radiation to damage the blood vessels and stop the blood supply to the AVM.

Deciding whether or not to treat an AVM is a decision that you and your doctor will discuss carefully together, weighing the possible benefits against the risks.

Follow-up

After treatment for an AVM, you may need regular follow-ups with your doctor. You may need more imaging tests to make sure that the AVM is completely resolved and that the malformation has not recurred. You may also need regular imaging tests and follow-up visits with your doctor if your AVM is being monitored.