Having trouble saying that long word? Another way to describe this condition is to call it "water on the brain."
Everyone's brain and spinal cord are cushioned by a liquid that's made inside the brain. This liquid usually flows from inside the brain to the outer part and then into the bloodstream. But sometimes an injury or other problem can block that flow. The fluid then builds up inside the head. A person with hydrocephalus may throw up, have headaches, or even changes in behavior.