A brain aneurysm, also referred to as a cerebral aneurysm or intracranial aneurysm (IA), is a weak bulging spot on the wall of a brain artery very much like a thin balloon or weak spot on an inner tube. Over time, the blood flow within the artery pounds against the thinned portion of the wall and aneurysms form silently from wear and tear on the arteries. 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 brain aneurysm commonly requires advanced surgical treatment.