An aneurysm in the brain is when the wall of an artery protrudes.
An arteriovenous malformation (AVM) is a malformation in the blood vessel system.
A dural arteriovenous fistula (DAVF) is a direct connection between an artery and a vein in the dura mater (dura). There is an increased pressure in the efferent vein.
A cavernoma (also called cavernous hemangioma) is a vascular malformation consisting of small vessels, tangle, and sometimes calcifications and connective tissue. This can occur in the brain and in the spinal cord.