Hydrocephalus is an abnormal (excessive) accumulation of fluid in the head.  The fluid is called cerebrospinal fluid, commonly referred to as CSF.  The CSF is located and produced within the fluid cavities of the brain called ventricles.  The function of CSF is to cushion the delicate brain and spinal cord tissue from injuries and maintain proper balance of nutrients around the central nervous system. 

Normally, most of the CSF produced on a daily basis is absorbed by the blood stream.  Everyday your body produces a certain amount of CSF, that same amount is absorbed by the brain.  When an imbalance occurs, an excess of CSF builds up in the ventricles resulting in a condition known as hydrocephalus.  Left untreated, hydrocephalus will create increased pressure in the head, which can cause neurological deficits or even death.

Hydrocephalus may be caused by one or more of the following:

• interference with the normal CSF flow, due to an obstruction or blockage in the CSF pathway, e.g. tumours or congential cause
• over-production of CSF
• under-absorption of CSF into the bloodstream.

There are two types of hydrocephalus:

• communicating hydrocephalus caused by the over-production or under-absorption of CSF
• non-communicating or obstructive hydrocephalus caused by a blockage of the CSF pathways.

Hydrocephalus is further deemed congenital if present before or since birth; or hydrocephalus can be acquired, developing after birth.  A variety of causes can contribute to acquired hydrocephalus; some are head injury, tumours and meningitis.