Osmosis video - Subarachnoid hemorrhage

A subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space, the area between the arachnoid membrane and the pia mater surrounding the brain. This may occur spontaneously, usually from a ruptured cerebral aneurysm, or may result from a head injury.

Symptoms of subarachnoid hemorrhage can include sudden, severe headache; nausea and vomiting, confusion, or reduced level of consciousness. Diagnosis is usually done with a CT or MRI that shows blood in the subarachnoid space and blood in a lumbar puncture. Treatment requires prompt surgery to stop the bleeding and prevent further damage. Medications may also be prescribed to reduce swelling and control seizures.