What is an Aneurysm?
A cerebral or intracranial aneurysm is an abnormal focal dilation of an artery in the brain that results from a weakening of the inner muscular layer (the intima) of a blood vessel wall. The vessel develops a "blister-like" dilation that can become thin and rupture without warning. The resultant bleeding into the space around the brain is called a subarachnoid hemorrhage (SAH). This kind of hemorrhage can lead to a stroke, coma, and/or death.
Aneurysms are usually found at the base of the brain just inside the skull, in an area called the subarachnoid space. In fact, 90 percent of SAHs are attributed to ruptured cerebral aneurysms and the two terms are often used synonymously.