Strokes fall into two categories: hemorrhage and focal cerebral ischemia.
Bleeding that occurs within the brain is called an intracerebral hemorrhage. This often results from high blood pressure. This bleeding can collect into an intracerebral hematoma, and the pressure this collection of blood places on the brain can create further injury.
Focal cerebral ischemia describes the condition in which the blood supply is reduced to an area of the brain. When death of tissue occurs, this is called a cerebral infarct. An infarct can occur when a thrombus (clot) or embolus (a clot that forms elsewhere in the body and travels to the brain) cuts off the supply of blood.
An aneurysm is a sac-like enlargement of the blood vessel. A cerebral aneurysm occurs when the wall of a blood vessel is weak and this weakened wall expands. If an aneurysm bursts, hemorrhage and damage can occur.
An arteriovenous malformation (AVM) can also cause hemorrhage. An AVM is a congenital malformation of the arteries and veins in the brain. These blood vessels are thin and fragile. As with an aneurysm, they may rupture and cause bleeding in the brain.
