Pontoneocerebellar hypoplasia--a probable consequence of prenatal destruction of the pontine nuclei and a possible role of phenytoin intoxication.

The autopsy findings of a 21/2-year-old microcephalic, mentally retarded girl, with tetraparesis, and dysmorphic features are reported. Neuropathologic findings, typical of the ponto-neocerebellar hypoplasia described by Brun [1917], suggest that this abnormality was the result of a prenatally acquired destruction of the pontine nuclei, with a secondary retrograde degeneration of the dentatopontine tract. The possible role of phenytoin, taken by the mother during pregnancy, is discussed.