Morphological evidence of brain stem but not cerebellar involvement in 12 autistic retarded children is reported from the University of Tokushima School of Medicine, Japan. Midsagittal MRIs showed that the brain stem was significantly smaller in the autistic group compared to 14 controls but not compared to 15 non-autistic retarded children, all groups of mean age 7 years (range, 5-10 years). The cerebellar vermis was not different among the three groups. The ratio of the midbrain to posterior fossa area was significantly smaller only in autistic patients. 
COMMENT. The authors suggest that in autism a specific brain stem lesion may be masked by a lesion of mental retardation. Further examination of autistic children with a normal IQ is planned.