Ventricular size and intelligence in achondroplasia.

Of 10 children with macrocephaly in association with achondroplasia only two children had progressive hydrocephalus. They were treated with a shunt procedure. One of these is intellectually and neurologically normal, and one is wheelchair bound and mentally retarded, with a spastic quadraplegia. Three children showed mild dilatation of the ventricles and one of these died from severe constriction at the foramen magnum. The other two are neurologically normal; one is intellectually normal but below average (WISC 88) and the other is slow normal at 18 months of age. Four children with demonstrated megalencephaly and a fifth with probable megalencephaly are all intellectually and neurologically normal. Intelligence in achondroplasia appears to be mainly in the normal range.