Tapering of the Cervical Spinal Canal in Patients with Scoliosis with and without the Chiari I Malformation

Trend line fit by least squares to the diameters of the spinal canal. The slope is −0.36, and the quality of fit (R²) is 0.5.

Average anteroposterior diameters of the cervical spinal canal plotted by cervical level in 4 groups of patients. The plots of the patients with Chiari and without syrinx appear similar as do the plots for the groups without Chiari malformation. The group with Chiari lacking a syrinx includes only 2 individuals, explaining perhaps the more erratic course of the plot. The other groups had ≥8 members.

Taper ratios for the 4 groups of patients for C1-C7 and for C1-C4. The patients with a Chiari malformation had significantly steeper taper ratios than those without it, for both taper ratio calculations. For convenience, the negative sign is omitted from the graph.