An Arteriovenous Malformation (AVM) is a congenital malformation of the vascular system in which arteries and veins are directly connected, bypassing capillaries. The result is a giant tangle of arteries and veins, and in space restricted areas like the brain you can imagine the negative affect one these can have on a person. The first-line treatment for an AVM is surgical embolization; they go in through the vascular system and cut the blood supply to the malformation off. The AVM then dies and stops putting pressure on the surrounding tissues. If the AVM is superficial in the brain they can perform a craniotomy and slowly shrink and remove the AVM.