Understanding what subarachnoid hemorrhage means

Where is the hemorrhage?

Brain with diffuse SAH

On top of the surface of the brain tissue is a layer called the arachnoid. It looks like cellophane. It is clear in young individuals, can become a little opaque as we all get older. Between this layer and the brain is cerebrospinal fluid which is circulating around the brain tissue. Blood vessels are also along the surface of the brain. These are the blood vessels which can be injured from trauma. When they bleed, the blood will mix and spread with the cerebral spinal fluid along the surfaces of the brain. Since it is below the arachnoid, it is called a subarachnoid hemorrhage. Other relatively common causes of subarachnoid hemorrhage include rupture of cerebral aneurysms and arterial venous malformations. Sometimes communicating hydrocephalus may develop after subarachnoid hemorrhage.

Subarachnoid Hemorrhage causing Communicating Hydrocephalus

CT of Brain with diffuse SAH

The CT Scan shows an enlarging ventricular system. The blood can be very irritating to the brain, causes inflamation which may result in decreased absorption of the CSF (Cerebral Spinal Fluid). The production of CSF continues so a net increase of CSF occurs. Thus, the ventricles begin to enlarge. Communicating Hydrocephalus may develop.