Hydrocephalus

What is Hydrocephalus? *

The term hydrocephalus is derived from the Greek words "hydro," meaning water, and "cephalus," meaning head. As its name implies, hydrocephalus is a condition in which the primary characteristic is excessive accumulation of fluid in the brain. Although hydrocephalus was once known as "water on the brain," the "water" is actually cerebrospinal fluid (CSF), a clear fluid surrounding the brain and spinal cord. The excessive accumulation of CSF results in an abnormal dilation of the spaces in the brain called ventricles. This dilation causes potentially harmful pressure on the tissues of the brain.

Cerebrospinal Fluid Dynamics

The ventricular system is made up of four ventricles connected by narrow pathways. Normally, CSF flows through the ventricles, exits into cisterns (closed spaces that serve as reservoirs) at the base of the brain that bathes the surfaces of the brain and spinal cord, and then is absorbed into the bloodstream.

Purpose of Cerebrospinal Fluid

CSF has three important life-sustaining functions:

  • Helps the brain tissue remain buoyant acting as a cushion or "shock absorber" 
  • Delivers nutrients to the brain and removes waste 
  • Flows between the head and spine to adjust with changes in intracranial blood flow within the brain

Production and Absorption of Cerebrospinal Fluid

The balance between production and absorption of CSF is critically important. Ideally, the fluid is almost completely absorbed into the bloodstream as it circulates; however, there are circumstances which, when present, will prevent or disturb the production or absorption of CSF, or inhibit its normal flow. When this balance is disturbed, hydrocephalus is the result.

* Information provided by the National Institute of Neurological Disorders and Stroke (NINDS).