HYDROCEPHALUS

accumulation of cerebrospinal fluid in the ventricles, or cavities, of the brain, causing progressive enlargement of the head, convulsion, and mental retardation. Normally, cerebrospinal fluid continuously circulates through the brain and its ventricles and the spinal cord and is continuously drained away into the circulatory system. In hydrocephalus the fluid accumulates in the two large lateral ventricles, and the brain and skull become enlarged because of the great volume of fluid pressing against them. The condition may result from an overproduction of the fluid, from a congenital malformation blocking normal drainage of the fluid, or from complications of head injuries or infections. Infants and young children with hydrocephalus have abnormally large heads because the pressure of the fluid has caused the individual skull boneswhich have not knitted with each other yetto bulge outward at their juncture points. Compression of the brain by the accumulating fluid eventually causes convulsions and mental retardation. Hydrocephalus occurs in one or two out of every 1,000 live births and was routinely fatal until surgical techniques for shunting the excess fluid out of the central nervous system and into the blood or abdomen were developed. Today it need not cause any intellectual impairment if recognized and properly treated.