Neuropathological study of a case of autistic syndrome with severe mental retardation.

Infantile autism is a syndrome of unknown aetiology and unknown neuro-anatomic substrate. The authors report a histological study of the brain of a well-documented 16-year-old female with autistic syndrome and severe mental retardation, using direct microscopic examination of the whole brain. The major findings are low brain weight, a thin corpus callosum and ventricular dilatation. No abnormalities were found in the hippocampus or cerebellum. Excessive axonal elimination during brain development is hypothesized. The relations of hypothetical developmental events with the clinical features of autistic syndrome are discussed.