The term hydrocephalus comes from two Greek words, hydro (water) and cephalus (head). The condition hydrocephalus is caused by water on the brain. A large amount of cerebrospinal fluid collects in the cavities of the brain which creates pressure on the skull. The result is an enlarged head, convulsions, and intellectual disability. Hydrocephalus can also be caused by too much cerebrospinal fluid being produced, which makes it difficult for the fluid to drain properly. Other causes are complicated head injuries and infections. Convulsions and mental retardation are caused when accumulated cerebrospinal fluid causes the brain to compress. Hydrocephalus happens in approximately one out of every 500 live births. In the past if was fatal. Today, however, shunts are inserted to remove extra fluid. If left untreated, hydrocephalus can result in mental retardation. Symptoms are: coma, papilledema, nausea, sleepiness, vomiting and headaches.