Brain Arteriovenous Malformations (AVM)What is an AVM?AVM stands for Arteriovenous Malformation. An AVM is a tangle of abnormal and poorly formed blood vessels (arteries and veins). They have a higher rate of bleeding than normal vessels. AVMs can occur anywhere in the body. Brain AVMs are of special concern because of the damage they cause when they bleed. They are very rare and occur in less than 1% of the general population. AVMs that occur in the coverings of the brain are called dural avms.