Hydrocephalus: the definition
A clear, saltwater-like liquid called cerebro-spinal fluid (CSF) surrounds the brain.
This fluid protects and nourishes the brain, carries away waste from brain cells and contains important chemicals and nutrients.
Each day the brain produces about a pint of fluid which flows in a continuous circuit through the brain cavities (ventricles) and over the surface of the brain and spinal cord until it is absorbed by the body.
If the drainage pathways are obstructed at any point, the fluid accumulates in the ventricles inside the brain, causing them to swell and resulting in compression of the surrounding tissue.
In babies and infants, the head will enlarge. In older children and adults, the head size cannot increase, as the bones that form the skull are completely fused together.