Paralysis Resource Guide - (Page 7) CONDITIONS ARTERIOVENOUS MALFORMATIONS Arteriovenous malformations (AVMs) are defects of the circulatory system that are believed to arise during fetal development or soon after birth. They are comprised of snarled tangles of arteries and veins. Arteries carry oxygen-saturated blood away from the heart to the body’s cells; veins return oxygen-depleted blood to the lungs and heart. The presence of an AVM disrupts this vital cycle, reducing oxygen to nervous system tissue and increasing the risk of bleeding. Arteriovenous malformations can form wherever arteries and veins exist. The ones that form in the brain or spinal cord can be especially problematic. Even in the absence of bleeding or significant oxygen loss, large AVMs can damage the brain or spinal cord by their presence. They can range in size from a fraction of an inch to more than 2.5 inches in diameter. The larger the lesion, the greater the amount of pressure there is on surrounding brain or spinal cord structures. AVMs of the brain or spinal cord (neurological AVMs) affect approximately 300,000 Americans. They occur in males and females of all racial or ethnic backgrounds at roughly equal rates. Common symptoms of AVMs are seizures and headaches. Other neurological symptoms may include muscle weakness or paralysis in one part of the body; loss of coordination (ataxia), pain, or disturbances of vision or speech. Mental confusion or hallucination is also possible. There is evidence that AVMs may also cause subtle learning or behavioral disorders during childhood. Diagnosis of AVM is by either computed axial tomography (CT) or magnetic resonance imaging (MRI) scans. Angiography is an accurate way to get the exact location of the malformation. A thin tube is inserted in a leg artery, threaded toward the brain and then injected with a dye. Pictures reveal the AVM tangle. Arteriovenous malformations can put veins under great pressure since there are no capillaries to slow blood flow. Over time, the AVM may rupture and cause a hemorrhage. While the risk of hemorrhage is small, the risk increases over time. Therefore, treatment is usually recommended. Treatment: Advances in technique have made surgical treat7
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