title: Tapering of the cervical spinal canal in patients with scoliosis with and without the Chiari I malformation.
abstract: BACKGROUND
  Cervical spinal canal tapering may increase CSF velocities and pressures. One report suggests that the cervical spinal canal tapers more steeply in patients with Chiari I than in healthy subjects. The goal of this study was to test the conclusion by measuring spinal canal tapering in another cohort of patients.
  
  
  METHODS
  Consecutive patients with scoliosis and MR imaging were selected. The MR images were evaluated for tonsillar herniation and syringomyelia. On a midline T2-weighted MR image, the anteroposterior diameter of the spinal canal was measured at each cervical level, and a linear trend line was fit by least-squares regression. The slope of this line was recorded as the taper ratio in millimeters/level. Patients with >5 mm of tonsillar herniation (with or without syrinx) were compared with those without tonsillar herniation (with or without syrinx). Differences in taper ratios for the 2 groups were tested for significance by the Kruskal-Willis test with significance set at .05.
  
  
  RESULTS
  Fifty-four patients with scoliosis were identified; 22 had a Chiari malformation and 32 did not. Syringomyelia was identified in 20 of the patients with Chiari and in 8 of the others. The taper ratios averaged -0.9 mm/level for the patients with a Chiari malformation (with or without a syrinx) and -0.4 mm/level for those without it, significant at P = .035. Syringomyelia did not substantially alter the taper ratio in either group.
  
  
  CONCLUSIONS
  Patients with scoliosis with a Chiari malformation have more steeply tapering cervical spinal canals than those without it.
authors.affiliation: Department of Radiology, University of Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI 53792, USA.
authors.forename: J
authors.initials: J
authors.lastname: Hammersley
authors.forename: V
authors.initials: V
authors.lastname: Haughton
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: A Munoz
authors.initials: AM
authors.lastname: del Rio
mesh_terms: D000293:Adolescent; D001139:Arnold-Chiari Malformation / Q000150:complications* / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D015203:Reproducibility of Results; D012600:Scoliosis / Q000150:complications* / Q000473:pathology*; D012680:Sensitivity and Specificity; D013115:Spinal Canal / Q000473:pathology*; D013130:Spinal Stenosis / Q000150:complications* / Q000473:pathology*; D055815:Young Adult