subarachnoid hemorrhage (SaH, SAH), an intracranial hemorrhage into the cerebrospinal fluid-filled space between the arachnoid and pial membranes on the surface of the brain. The hemorrhage may extend into the brain if the force of the bleeding from the broken vessel is sudden and severe. The cause may be trauma, rupture of an aneurysm, or an arteriovenous anomaly. ▪ OBSERVATIONS: The first symptom of a subarachnoid hemorrhage is a sudden, extremely severe headache that begins in one localized area and then spreads, becoming dull and throbbing. It is frequently described by patients as “the worst headache of my life.” The localized pain results from vascular distortion and injury. The generalized ache is the result of meningeal irritation by blood in the subarachnoid space. Other characteristics of subarachnoid hemorrhage can include dizziness, rigidity of the neck, pupillary inequality, vomiting, seizures, drowsiness, sweating and chills, stupor, and loss of consciousness. A brief period of unconsciousness immediately after the rupture is common; severe hemorrhage may result in continued unconsciousness, coma, and death. Delirium and confusion often persist through the first weeks of recovery, and permanent brain damage is common.
