title: Analysis of the posterior fossa in children with the Chiari 0 malformation.
abstract: OBJECTIVE
  We previously reported the resolution of syringohydromyelia without cerebellar tonsillar ectopia in five patients after posterior fossa decompression of the so-called Chiari 0 malformation. A sixth patient is described. In this study, the anatomy of the posterior fossa is analyzed using radiological imaging, enabling features of the posterior fossa in this uncommon subgroup of children to be characterized.
  
  
  METHODS
  Multiple measurements were made on magnetic resonance imaging studies in six children with Chiari 0 malformation to determine the position of the brainstem relative to the foramen magnum. Fifty children with normal magnetic resonance imaging studies of the brain were used as controls.
  
  
  RESULTS
  All children with a Chiari 0 malformation were found to have the following positive results: obices that were located more than 2 standard deviations below normal, an increase in the anteroposterior midsagittal distance of the spinomedullary junction at the level of the foramen magnum, an increase in the angle between the floor of the fourth ventricle and clivus, and an increase in the anteroposterior midsagittal distance of the foramen magnum.
  
  
  CONCLUSIONS
  The findings of this study suggest that the contents of the posterior fossa are indeed compromised and/or distorted in patients with syringohydromyelia but no tonsillar ectopia. In this group, the brainstem was caudally displaced more than 3 standard deviations below normal.
authors.affiliation: Pediatric Neurosurgery, The Children's Hospital of Alabama, University of Alabama at Birmingham, 35233, USA.
authors.forename: R S
authors.initials: RS
authors.lastname: Tubbs
authors.forename: S
authors.initials: S
authors.lastname: Elton
authors.forename: P
authors.initials: P
authors.lastname: Grabb
authors.forename: S E
authors.initials: SE
authors.lastname: Dockery
authors.forename: A A
authors.initials: AA
authors.lastname: Bartolucci
authors.forename: W J
authors.initials: WJ
authors.lastname: Oakes
mesh_terms: D000293:Adolescent; D001139:Arnold-Chiari Malformation / Q000175:diagnosis*; D001933:Brain Stem / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D003388:Cranial Fossa, Posterior / Q000473:pathology*; D005260:Female; D005539:Foramen Magnum / Q000473:pathology; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D012016:Reference Values; D012189:Retrospective Studies