A subarachnoid hemorrhage is a devastating disease that accounts for less than 10 percent of all strokes, but takes the lives of five percent of all stroke victims. This type of stroke occurs when blood escapes from vessels and enters the subarachnoid space of the brain where cerebrospinal fluid circulates around the brain and spinal cords and into the ventricular system.

Subarachnoid hemorrhages can result from trauma or from ruptured aneurysms or arteriovenous malformations (AVM).

Diagnosis
Neuroimaging technologies are used to diagnose subarachnoid hemorrhages such as: CT scans, Magnetic Resonance Imaging (MRI) and angiography. Lumbar punctures are sometimes performed.