title: Posterior fossa magnetic resonance imaging in autism.
abstract: OBJECTIVE
  To determine whether the sizes and volumes of the posterior fossa structures are abnormal in non-mentally retarded autistic adolescents and adults.
  
  
  METHODS
  Volume measurements of the cerebellum, vermis, and brainstem were obtained from coronal magnetic resonance imaging scans in 16 autistic subjects and 19 group-matched healthy controls. For the purpose of comparison with previous studies, area measurements of the midbrain, pons, medulla, total cerebellar vermis, and its three subregions were also obtained from a larger sample of 22 autistic males (mean age: 22.4 years; range: 12.2-51.8 years) and 22 individually matched controls (mean age 22.4 years; range: 12.9-52.2 years).
  
  
  RESULTS
  The total volume of the cerebellum and the cerebellar hemispheres were significantly larger in the autistic subjects with and without correcting for total brain volume. Volumes of the vermis and the brainstem and all area measurements did not differ significantly between groups.
  
  
  CONCLUSIONS
  There is an increase in the volume of the cerebellum in people with autism consistent with the increase in regional and total brain size reported in this developmental disorder. This finding is also concordant with evidence of cerebellar abnormalities from neuropathological and neuropsychological studies that point to the role of this structure, as part of a complex neural system, in the pathophysiology of autism.
authors.affiliation: Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, PA 15213, USA. hardanay@msx.upmc.edu
authors.forename: A Y
authors.initials: AY
authors.lastname: Hardan
authors.forename: N J
authors.initials: NJ
authors.lastname: Minshew
authors.forename: K
authors.initials: K
authors.lastname: Harenski
authors.forename: M S
authors.initials: MS
authors.lastname: Keshavan
mesh_terms: D000293:Adolescent; D000328:Adult; D001321:Autistic Disorder / Q000175:diagnosis*; D001933:Brain Stem / Q000002:abnormalities; D002531:Cerebellum / Q000002:abnormalities; D002648:Child; D003388:Cranial Fossa, Posterior / Q000002:abnormalities*; D001330:Electronic Data Processing; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008526:Medulla Oblongata / Q000002:abnormalities; D008875:Middle Aged; D011149:Pons / Q000002:abnormalities