Congenital granuloprival hypoplasia of cerebellar and hippocampal cortex.

Two siblings with congenital granule cell hypoplasia of the cerebellum and hippocampus are reported. The patients, both male, showed severe psychomotor retardation, microcephaly, hypotonia, athetosis, and seizures; they died at the ages of 3 7/12 years and 5 10/12 years, respectively. Postmortem examinations in both cases revealed nearly complete absence of the granule cells of the cerebellum with relative preservation of the Purkinje cells. Also absent were the granule cells of the fascia dentata of the Ammon's horns of the hippocampus, without any detectable gliosis; this has not previously been reported. Twenty-three autopsy cases of granuloprival cerebellar hypoplasia are reviewed. The present cases illustrate a singularly unique disease process, comparable to the classical cerebellar hypoplasia experimentally induced by parvoviruses, and suggest a granule cell specific insult to the brain during the late second trimester.