A brain aneurysm - also called a cerebral or intracranial aneurysm - begins at the base of the brain as a small thinned out area on the wall of an artery. Over time, the blood flow within the artery pounds against the thinned portion of the wall causing it to weaken.
As the artery wall becomes gradually thinner from the dilation, the blood flow causes the weakened wall to swell outward. This pressure may cause the aneurysm to rupture and allow blood to escape into the space around the brain. A ruptured aneurysm commonly requires advanced surgical treatment.
Why do aneurysms form?
There is currently no proven cause for aneurysms. Although it has been theorized that since most arteries in the body have walls with three layers and the brain's arteries have segments where one layer is missing, the artery wall of the brain is more likely to weaken.
It is also believed by some doctors that people may be predisposed at birth, while others feel that high blood pressure and conditions that induce stress on the arteries are significant contributors.
How are aneurysms diagnosed after they rupture?
When an aneurysm ruptures, the bleeding can be minimal, moderate or severe. A person's physical response to the hemorrhage will most often be related to the amount of blood that escapes from the aneurysm and around the brain.
The initial evaluation of the aneurysm will typically occur in the emergency room following symptoms of a severe headache.