title: Tapering of the cervical spinal canal in patients with Chiari I malformations.
abstract: OBJECTIVE
  Upper cervical spinal canal dimension may have a role in abnormal CSF dynamics in patients with Chiari I malformation. We attempted to measure spinal canal tapering from anteroposterior spinal canal dimensions in patients with Chiari I.
  
  
  METHODS
  Twenty-one patients with Chiari I malformation, including 12 with syringomyelia and 7 patients with IS were identified from a local registry. Age- and sex-matched control subjects with cervical spine MR imaging findings reported as normal were selected from the PACS. The anteroposterior diameter of the spinal canal was measured at C1-C7 on T2-weighted sagittal MR images. The taper ratio of the spinal canal was calculated with the regression line. Goodness of fit was calculated as R(2). Differences between patients with Chiari I and other patients were tested for significance with Kruskal-Wallis tests and multivariate analysis.
  
  
  RESULTS
  Taper ratios averaged -0.6 ± 0.3 mm/level in the patients with Chiari and syrinx, -0.4 ± 0.2 mm/level (mean ± 1 SD) in the patients with Chiari without syrinx, and -0.3 ± 0.5 mm/level in the patients with IS; control groups had average taper ratios of -0.3 ± 0.2 mm/level. Mean R(2) equaled 0.43. Taper ratios in patients with Chiari and syringomyelia differed significantly from those in the control group (P = .003). Taper ratios in the patients with Chiari without syrinx and in patients with IS did not differ significantly from their matched control groups (P = .60 and 0.76, respectively).
  
  
  CONCLUSIONS
  Patients with Chiari I and a syrinx have steeper tapering of the upper cervical spinal canal than matched controls.
authors.affiliation: University of Wisconsin, Madison, Wisconsin 53792, USA.
authors.forename: M
authors.initials: M
authors.lastname: Hirano
authors.forename: V
authors.initials: V
authors.lastname: Haughton
authors.forename: A
authors.initials: A
authors.lastname: Munoz del Rio
mesh_terms: D000293:Adolescent; D001139:Arnold-Chiari Malformation / Q000473:pathology*; D002574:Cervical Vertebrae / Q000002:abnormalities* / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013115:Spinal Canal / Q000002:abnormalities* / Q000473:pathology*; D013130:Spinal Stenosis / Q000473:pathology*; D055815:Young Adult