In addition, the blood's weight presses on the brain cells beneath it. Hemorrhagic strokes are called subarachnoid when they occur between the skull and the dura, or the delicate membrane surrounding the brain. When the hemorrhage is below the dura, within the brain, it is intracerebral. Aneurysms are a common source of hemorrhagic strokes. Aneurysms are balloon-like bulges of artery walls.
Most aneurysms are stable for decades.
But if an aneurysm grows, the wall becomes weaker. Aneurysms frequently cause no symptoms, but when they enlarge can produce headache, double vision, loss of vision, facial numbness, enlarged pupil size or drooping eyelid. Aneurysms can be surgically repaired, depending on their location. Hemorrhage causes 17 percent of strokes. Ten percent of these are intracerebral, and seven percent are subarachnoid.