Subarachnoid hemorrhage refers to the bleeding in the subarachnoid area of the brain due to the rupture of a blood vessel. The subarachnoid area is the space between the brain and the skull. This space fills up with blood and puts pressure on the brain which can result in symptoms such as severe headache, vomiting and even loss of consciousness and death. The hemorrhage can be due to such things as cerebral aneurysm or head injuries.

Subarachnoid hemorrhage occurs when a blood vessel on the surface of the brain bursts and blood flows into the small cavity that surrounds the brain, the subarachnoid space.