AVMs are malformed blood vessels that cause direct and irregular connections between arteries and veins due to an absence of capillaries—a network of small blood vessels that delivers oxygen to cells. In most cases, AVMs cause damage by reducing the amount of oxygen reaching brain tissue and by compressing or displacing parts of the brain. Over time, increased blood flow through arteries directly into veins can cause some AVMs to grow progressively larger, weaken, and rupture, causing hemorrhagic stroke.
A hemorrhagic stroke is a serious medical condition that occurs when blood from damaged or ruptured blood vessels seeps into or around the brain. Intracranial bleeding disrupts the brain’s oxygen supply and upsets the chemical balance that brain cells need to function. The resulting blood clot (hematoma) can cause the brain to swell (edema) and increase intracranial pressure, which can cause further oxygen deprivation.
IMPORTANT NOTE: This overview is provided for informational purposes only and should not be used as a substitute for talking with your doctor. Be sure to talk with your doctor for a complete discussion of this condition as well as the benefits and risks of any treatment options.