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Tapering of the central spinal canal in patients with Chiari I 2012

General Spine

Jill, A, Hammersley, M.D.
Yonker, Wang, M.D., Non ASSR Member
Alejandro, Munoz Del Rioz, Ph.D., Non ASSR Member
Victor, Haughton, M.D., Non ASSR Member

Paper/Mentor

Purpose

Cervical spinal canal tapering may increases CSF velocities and pressures. One report suggests that the cervical spinal canal tapers more steeply in Chiari I patients than in normal subjects. The goal of this study was to test the conclusion by measuring spinal canal tapering in another cohort of patients.

Methods & Materials

Consecutive patients with scoliosis and MR imaging were selected. The MR images were evaluated for tonsilar herniation and syringomyelia. On a midline T2 weighted MR image, the anterior-posterior diameter of the spinal canal was measured at each cervical level, and a linear trendline was fit to the them by least-squares regression. The slope of this line was recorded as the taper ratio in mm/level. Patients with more than 5 mm of tonsilar herniation (with or without syrinx) were compared to those without tonsilar herniation (with or without syrinx). Differences in taper ratios for the two groups were tested for significance by the Kruskal-Willis test with significance set at 0.05.

Results

Fifty-four scoliotic patients were identified; 22 had a Chiari malformation and 32 did not. Syringomyelia was identified in 20 of the Chiari patients 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 the patients without a Chiari, significant at p = 0.035. Syringomyelia did not substantially alter the taper ratio in either group.

Conclusion

Scoliotic patients with a Chiari malformation have more steeply tapering cervical spinal canals than scoliotic patients without it.

References/Financial Disclosures

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