Investigation of a contributing factor for cervical vertebral stenotic myelopathy using computed tomography for measuring the cervical vertebral volume

Abstract

Thoroughbred horses appear to be particularly predisposed to cervical vertebral stenotic myelopathy (CVSM), also known as wobbler syndrome. We hypothesized that variations in the cervical vertebral volumes can affect the dynamic instability of the cervical vertebrae. This observational study aimed to clarify whether cervical vertebral volume could be considered as a contributing factor in CVSM in Thoroughbred horses. Computed tomography (CT) was used to investigate a total of 21 male Thoroughbred horses (age range, 217-1,002 days; mean, 542.3 days). The study population comprised 17 CVSM horses (age range, 217-1,002 days; mean, 549.8 days) and 4 non-CVSM horses (age range, 244-682 days; mean, 510.5 days). The cervical vertebral volumes of three-dimensional CT were measured using the image-processing software. A significant difference in the variation of cervical vertebral volumes among C2 to C4 and C3 to C5 was identified in the CVSM group (P<0.05). While no significant differences were found in the variation in cervical vertebral volumes among C4 to C6. C3 demonstrated a significantly smaller cervical vertebral volume than C2 and C4 (P<0.05). In the non-CVSM group, no significant differences were found in the variation of cervical vertebral volume among C2 to C4, C3 to C5, and C4 to C6. Our findings suggest that variations in cranial cervical vertebral volume in CVSM male horses can be considered as an important contributing factor in CVSM development.

Keywords: Thoroughbred horse; cervical vertebral stenotic myelopathy; cervical vertebral volume; computed tomography.

Fig. 1.

The cervical vertebral volume measurements ranged from C2 to C6 (A). The cervical vertebral area (200–1,500 HU), wherein the region of interest was shown the green area, was measured in the two-dimensional transverse plane (B-1, 2). Three-dimensional images were reconstructed using the volume rendering technique to calculate the cervical vertebral volumes.

Fig. 2.

Box-and-whisker plot of cervical vertebral volumes in cervical vertebral stenotic myelopathy horses. C3 demonstrated a significantly smaller cervical vertebral volume than C2 and C4 (*P<0.05).

Fig. 3.

Box-and-whisker plot of cervical vertebral volumes in non-cervical vertebral stenotic myelopathy horses. No significant differences were found in the variation of cervical vertebral volumes.