• Arteriovenous Malformations

    (AVM; Arteriovenous Malformations of the Brain; AMB)

    Definition

    Arteriovenous malformations (AVM) of the brain and spinal cord are tangles of abnormal blood vessels. They can form wherever arteries and veins exist. The ones that form in the brain or spinal cord have the most serious symptoms.
    Arteries in arteriovenous malformations don’t flow properly. They dump blood directly into veins through a channel called a fistula, an abnormal tube-like opening. The blood flows through this fistula too quickly.
    Arteriovenous Malformation in the Brain
    AVM brain blood vessels
    Copyright © Nucleus Medical Media, Inc.
    If you suspect you have this condition, contact your doctor immediately.

    Causes

    The exact cause of arteriovenous malformations is unknown.

    Risk Factors

    Risk factors that increase your chance of getting arteriovenous malformations include:
    • Family history—some types of arteriovenous malformations are from genetic defects that can be passed on from one generation to the next.
    • History of bleeding—some types of arteriovenous malformations are linked to an increased risk of bleeding. People with unexplained recurrent bleeding may be at higher risk of having arteriovenous malformations.
    • Smoking

    Symptoms

    There are a number of symptoms that you may have if you have an arteriovenous malformation. Symptoms vary from person to person. They also depend on the location of the arteriovenous malformation in your body.
    If you have any of these symptoms, do not assume it is due to arteriovenous malformations. These symptoms may be caused by other, less serious health conditions.
    • Seizure—occurs in 20%-25% of all cases
    • Headache
      • Headaches are a common symptom that affect about 15% of cases. Sometimes headaches linked to one side of the head may be a sign that an arteriovenous malformation is there.
    • Muscle weakness
    • Paralysis (loss of movement) on one side of the body
    • Dizziness
    • Unable to perform movements but not due to paralysis (also known as apraxia)
    • Loss of coordination, especially when walking (also known as ataxia)
    • Sudden, severe back pain
    • Difficulty speaking or understanding language
    • Loss of senses (hearing, taste, or touch)
    • Visual problems
    • Memory loss
    • Difficulty thinking or mental confusion
    • Hallucinations (sensing things that do not exist)
    • Dementia
    Children under the age of two may have different symptoms such as:
    • Hydrocephalus (excessive build-up of fluid within the brain—gives the appearance of a large head)
    • Seizures

    Diagnosis

    Your doctor will ask about your symptoms and medical history. A physical exam will be done.
    Your doctor will need more information to make an evaluation. Your doctor may order some tests to get a full understanding of your condition.
    Your doctor may need pictures of your body structures. This can be done with:
    Your doctor will most likely refer you to a specialist for an exam and treatment. There are a number of specialists who focus on arteriovenous malformation such as neurologists, neurosurgeons, and interventional neuroradiologists.

    Treatment

    The goal of treatment is to prevent hemorrhaging. Hemorrhaging can lead to strokes. Your doctor will need to determine if your arteriovenous malformation has bled, if it is not too large, and if it is in an area that can be easily reached and treated.
    Talk with your doctor about the best treatment plan for you. Treatment options include the following:

    Medication

    Medication may be taken to ease the symptoms you may be having, such as headache, back pain, and seizures. This does not remove the arteriovenous malformation.

    Surgery

    You must work with your doctor to decide whether you’d like to have surgery to treat your arteriovenous malformation. Leaving an arteriovenous malformation untreated may lead to serious complications. However, there is always a risk of nervous system damage with surgery.
    There are three different types of surgery available. Choosing a surgery type will depend on the size and location of the arteriovenous malformation. The types of surgery include:
    There are three different types of surgery available. Choosing a surgery type will depend on the size and location of the arteriovenous malformation. The types of surgery include:

    Conventional Surgery

    This standard surgery involves operating on the area of the brain or spinal cord where the arteriovenous malformation is located. This procedure is the most thorough treatment for arteriovenous malformations.

    Endovascular Embolization

    Endovascular embolization is often used for arteriovenous malformations that are located deeper within the brain. Regular surgery could damage the surrounding tissue in the brain or spinal cord.
    A surgeon will guide a catheter through your arteries until it reaches the arteriovenous malformation. Then a substance will be inserted to plug the fistula. This procedure does not destroy the arteriovenous malformation. It reduces the blood flow to the arteriovenous malformation and makes surgery safer.

    Radiosurgery

    This procedure uses a beam of powerful radiation. The beam is focused directly on the arteriovenous malformation. The radiation damages the walls of the blood vessels that lead to the arteriovenous malformation. This procedure does not always completely destroy the arteriovenous malformation, especially if it is very large.
    Sometimes, arteriovenous malformations are best left alone based on their size and location. It is best to speak with your physician about your decision.
    Sometimes, arteriovenous malformations are best left alone based on their size and location. It is best to speak with your physician about your decision.

    Prevention

    There is no way to prevent an arteriovenous malformation. To help reduce your chances of hemorrhaging, take the following steps:
      Learn about ways to avoid high blood pressure, such as:
      • Avoid heavy lifting.
      • Stop smoking.
      • Maintain a healthy weight.
      • Limit alcohol.
      • Eat a healthy diet that is low in sodium.
    • Avoid blood thinners (drugs such as warfarin).
    • Continue to see your doctor and a neurologist to regularly check the condition of your arteriovenous malformation.

    RESOURCES

    American Stroke Association http://www.strokeassociation.org/

    National Institute of Neurological Disorders and Stroke (NINDS) http://www.ninds.nih.gov

    CANADIAN RESOURCES

    HealthLink BC http://www.healthlinkbc.ca/

    The Toronto Brain Vascular Malformation Study Group http://brainavm.uhnres.utoronto.ca/

    References

    Arteriovenous malformation information page. National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/disorders/avms . Updated July 13, 2012. Accessed November 26, 2012.

    Choi JH, Mohr JP. Brain arteriovenous malformations in adults. Lancet Neurology . 2005; 4(5):299-308.

    Geibprasert, et al. Radiologic assessment of brain arteriovenous malformations: what clinicians need to know. Radiographics . 2010;30(2):483-501.

    Ogilvy CS, Stieg PE, Awad I, et al. Recommendations for the management of intracranial arteriovenous malformation: a statement for healthcare professionals from a special writing group of the Stoke Council, American Stroke Association. Stroke . 2001;32:1458.

    Van Beijnum J, et al. Treatment of brain arteriovenous malformations: a systematic review and metanalysis. JAMA. 2011;306(18):2011-9.

    What is an arteriovenous malformation (AVM)? American Stroke Association website. Available at: http://www.strokeassociation.org/STROKEORG/AboutStroke/TypesofStroke/HemorrhagicBleeds/What-Is-an-Arteriovenous-Malformation-AVM%5FUCM%5F310099%5FArticle.jsp . Updated November 12, 2012. Accessed November 26, 2012.

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