The brain has many arterial blood
vessels that supply blood pumped by the heart. When the wall
of a blood vessel becomes weak and/or thin, it forms a bulge
or a bubble. This bulge or bubble is called an aneurysm.
An aneurysm may press on areas of the brain and cause various symptoms (below). Aneurysms may also rupture, causing bleeding in the brain. This bleeding results in Subarachnoid Hemorrhage (bleeding into the subarachnoid space
of the brain).
Focal neurological deficits
depending on location; for example, if the aneurysm
compresses the area of brain controlling the left leg, then
left leg weakness will occur.