The risk of bleeding may be higher for certain types of AVMs or if there's been a previous AVM rupture. This risk of a brain AVM bleeding ranges from around 2% to 3% each year. This may result in the AVM rupturing and bleeding into the brain. An AVM puts extreme pressure on the walls of the affected arteries and veins, causing them to become thin or weak.
It's also possible to inherit other medical conditions that increase the risk of brain AVMs, such as hereditary hemorrhagic telangiectasia (HHT).Ī brain AVM may cause bleeding in the brain (hemorrhage), which can damage the surrounding brain tissue, as shown by this CT scan (left) and illustration (right) of an intracerebral hemorrhage.īleeding in the brain. In rare cases, brain AVMs have been reported to occur in families, but it's unclear if there's a certain genetic factor or if the cases are only coincidental. Risk factorsĪnyone can be born with a brain AVM, but these factors may raise the risk: Instead, blood flows quickly and directly from the arteries to the veins, bypassing the surrounding tissues. The arteries and veins in an AVM lack this supporting network of smaller blood vessels and capillaries. The oxygen-depleted blood passes into small blood vessels and then into larger veins that return the blood to the heart and lungs to get more oxygen. The capillaries slowly deliver oxygen through their thin, porous walls to the surrounding brain tissue.
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The arteries slow blood flow by passing it through a series of progressively smaller networks of blood vessels, ending with the smallest blood vessels (capillaries). Typically, the heart sends oxygen-rich blood to the brain through arteries. HHT affects the way blood vessels form in several areas of the body, including the brain. Brain AVMs are seen in some people who have hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome. Researchers believe most brain AVMs are present at birth and form during fetal development, but brain AVMs can develop later in life, as well. In an arteriovenous malformation (AVM), blood passes quickly from an artery to a vein, disrupting the usual blood flow and depriving the surrounding tissues of oxygen. A bleeding brain AVM is life-threatening and requires emergency medical attention. Seek immediate medical attention if you notice any signs or symptoms of a brain AVM, such as seizures, headaches or other symptoms. It can also cause swollen veins that are visible on the scalp, seizures, failure to thrive and congestive heart failure. The major blood vessel involved in this type of brain AVM can cause fluid to build up in the brain and the head to swell. It causes signs and symptoms that emerge soon or immediately after birth. One severe type of brain AVM involves the vein of Galen. Research hasn't found that pregnancy increases the risk of hemorrhage for people with a brain AVM. The effects slowly build and often cause symptoms in early adulthood.īy middle age, however, brain AVMs tend to remain stable and are less likely to cause symptoms. Brain AVMs can damage brain tissue over time. Signs and symptoms of a brain AVM may begin at any age but usually emerge between ages 10 and 40.
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