An AVM is an abnormal tangle of blood vessels connecting arteries and veins, which disrupts normal blood flow and oxygen circulation. When an arteriovenous malformation (AVM) occurs, a tangle of blood vessels in the brain bypasses normal brain tissue and directly diverts blood from the arteries to the veins.
This usually happens during development before birth or shortly after. AVMs vary in size and location in the brain. An AVM rupture occurs because of pressure and damage to the blood vessel. This allows blood to leak (hemorrhage) into the brain or surrounding tissues and reduces blood flow to the brain.
Some people with brain AVMs experience signs and symptoms, such as headache or seizures. The biggest concern related to AVMs is that they will cause uncontrolled bleeding, or hemorrhage. Fewer than 4% of AVMs hemorrhage, but those that do can have severe, even fatal, effects.
Symptoms may begin at any age but usually emerge between ages 10 and 40. Brain AVMs can damage brain tissue over time. The effects slowly build up and often cause symptoms in early adulthood.
Arteriovenous malformation
