Definition: Hydrocephalus is a condition in which there is too much cerebrospinal fluid in the brain. The excess fluid causes increased pressure on the brain and can cause headaches, vomiting and nausea, blurry vision, balance problems, bladder control problems, and thinking and memory problems. Hydrocephalus can occur at birth due to a genetic abnormality or a problem with development or after birth due to an injury, infection, or tumor. Treatment options may include surgery to add a shunt to remove the excess fluid from the brain.