What is a subarachnoid hemorrhage?

A subarachnoid hemorrhage is the bursting of a blood vessel in the brain. This results in sudden bleeding into the space between the middle lining of the brain (arachnoid membrane) and the brain itself.

A subarachnoid hemorrhage causes sudden, severe head pain. This condition requires immediate medical care to prevent brain injury and death.

A subarachnoid hemorrhage is a type of stroke. It is a hemorrhagic (bleeding) stroke that occurs inside the head, in the surroundings of the brain.

The most common presenting symptom is a severe headache ("worst headache of my life"). It is diagnosed with a head CT that shows the hemorrhage and/or a spinal tap (lumbar puncture) that demonstrates blood in the spinal fluid. A subarachnoid hemorrhage is an emergency as there is a high incidence of morbidity and mortality associated with it.

The most dangerous cause of a subarachnoid hemorrhage is a brain aneurysm (outpouching or weak spot of an artery of the brain). Other potential causes include an AVM (arteriovenous malformation or abnormal connection between arteries and veins), trauma to the head, ingestion of cocaine or other stimulants, and inflammation of arteries of the brain (vasculitis). In approximately 15 percent of cases, the cause is never found and is presumed to be due to a small vein that ruptures (this type of hemorrhage is a more benign one, without major morbidity and mortality associated with it).

Patients with subarachnoid hemorrhage need to be admitted to the intensive care unit for monitoring and need a work up and treatment for the cause to the bleeding, in order to prevent it from happening again. The final recovery depends on the initial cause of hemorrhage and the initial clinical state at the time of presenting to the hospital.