Is Curve Direction Correlated With the Dominant Side of Tonsillar Ectopia and Side of Syrinx Deviation in Patients With Single Thoracic Scoliosis Secondary to Chiari Malformation and Syringomyelia?

Abstract

A retrospective imaging study. To conduct an assessment of the correlation of the coronal asymmetries between tonsillar ectopia, syrinx, and scoliosis. A few reports have shown that the convex side of scoliosis was on the same side as the dominant tonsillar ectopia or syrinx deviation in a majority of patients. However, this issue remains controversial. A retrospective study was conducted on young patients with a single thoracic scoliosis secondary to Chiari malformation type I and syringomyelia. The curve direction, side of the dominant tonsillar ectopia and side of the syrinx deviation were recorded and assessed quantitatively. The correlations between the asymmetrically displaced tonsils, eccentrically located syrinx, and curve convexity were investigated. A total of 39 patients were included. The concordance between the deviated side of the eccentrically located syrinx and dominant side of the asymmetrically displaced tonsils was 87.0%. In 88.5% of the patients with an asymmetrically displaced tonsil, the convex side of the scoliosis was concordant with the dominant side of the tonsillar ectopia, and in 86.2% of patients with an eccentrically located syrinx, the convex side of the scoliosis was on the same side as the deviated side of the syrinx. In addition, the dominant tonsillar ectopia, syrinx deviation, and curve direction were all on the same side in 82.6% patients with asymmetrically displaced tonsils and eccentrically located syrinx. Asymmetrically displaced tonsils and eccentrically located syrinxes were common imaging features in these patients. The thoracic spine tended to be convex to not only the dominant side of the asymmetrically displaced tonsil, but also the deviated side of the eccentrically located syrinx. The effect of syrinx deviation on curve convexity is similar to that of dominant tonsillar ectopia in the majority of patients.