brain, spinal cord, and nerve disorders
Subarachnoid Hemorrhage (SAH)
Introduction
A subarachnoid hemorrhage is bleeding into the space (subarachnoid space) between the inner layer (pia mater) and middle layer (arachnoid mater) of the tissues covering the brain (meninges). The most common cause is rupture of a bulge (aneurysm) in an artery. Usually, rupture of an artery causes a sudden, severe headache, often followed by a brief loss of consciousness. Computed tomography or magnetic resonance imaging, sometimes a spinal tap, and angiography are done to confirm the diagnosis. Medications are used to relieve the headache and to control blood pressure, and surgery is done to stop the bleeding. (See also Overview of Stroke and A subarachnoid hemorrhage is a life-threatening disorder that can rapidly result in serious, permanent disabilities. It is the only type of stroke more common among women than among men. When blood vessels of the brain are weak, abnormal, or under unusual pressure, a hemorrhagic stroke can occur. In hemorrhagic strokes, bleeding may occur within the brain, as an intracerebral hemorrhage. Or bleeding may occur between the inner and middle layer of tissue covering the brain (in the subarachnoid space), as a subarachnoid hemorrhage. 