Cervical spondylomyelopathy in Great Danes: a magnetic resonance imaging morphometric study

Abstract

Morphometric investigations comparing normal and affected animals increase our understanding of spinal diseases in dogs. The aim of this study was to generate morphometric data for osseous-associated cervical spondylomyelopathy (CSM) in Great Danes (GDs). Magnetic resonance imaging (MRI) morphometric features of the cervical vertebral column of GDs with and without clinical signs of CSM were characterized and compared. Thirty client-owned GDs were prospectively enrolled, including 15 clinically normal and 15 CSM-affected GDs. All dogs underwent MRI of the cervical to thoracic vertebral column (C2-C3 through T1-T2). Areas of the cranial and caudal articular processes, and the height, width and areas of the vertebral canal and spinal cord were determined. Middle foraminal heights were measured. Intervertebral disc width was measured before and after traction. Intraobserver and interobserver agreement were calculated. CSM-affected GDs had larger areas of the caudal articular processes from C2-C3 through T1-T2. In CSM-affected GDs, the vertebral canal and spinal cord areas were significantly smaller at C5-C6 and C6-C7, the vertebral canal width was significantly narrower at C6-C7 and C7-T1, and the spinal cord width was significantly narrower at C5-C6 and C6-C7. Middle foraminal height was smaller in CSM-affected GDs from C3-C4 through C7-T1. Neutral intervertebral disc widths were smaller in CSM-affected GDs. It was concluded that the cervical vertebral canal dimensions are significantly different between normal and CSM-affected GDs. Absolute vertebral canal stenosis and severe foraminal stenosis involving the cervical vertebrae distinguish CSM-affected from clinically normal GDs. These findings are relevant to the pathogenesis of osseous-associated CSM and should be taken into consideration when performing imaging studies and planning surgery.

Keywords: Canine; Osseous-associated cervical spondylomyelopathy; Spinal cord; Stenosis; Wobbler syndrome.

Fig. 1

Transverse T1-weighted image at the center of the C6–C7 intervertebral space of a clinically normal Great Dane, demonstrating the measurements obtained for the area of the articular processes. The caudal articular process of the cranial vertebral body is outlined in blue (a) and the cranial articular process of the caudal vertebral body is outlined in yellow (b). R, right side.

Fig. 2

Transverse T2-weighted image at the center of the C5–C6 intervertebral space of a clinically normal Great Dane, depicting the location of the following measurements: (a) spinal cord area (red), (b) spinal cord height (orange), (c) spinal cord width (blue) and (d) right and left middle foraminal heights (yellow). R, right side.

Fig. 3

Mean area and 95% confidence interval (CI) of the caudal and cranial articular processes measured at the center of the intervertebral space. Bars represent mean values and whiskers represent upper and lower limits of 95% CI. Cau Pro, caudal articular process of the cranial vertebra for that intervertebral disc level; Cra Pro, cranial articular process of the caudal vertebra; CSM, Great Dane (GD) with cervical spondylomyelopathy (CSM); N, unaffected (normal) GD. *P < 0.05.

Fig. 4

Mean vertebral canal area (VCA) and 95% confidence interval (CI) measured at the caudal aspect of the cranial vertebral body (VCA_cra), at the center of the intervertebral space (VCA_IVD) and at the cranial aspect of the caudal vertebral body (VCA_cau). Bars represent mean values and whiskers represent upper and lower limits of 95% CI. CSM, Great Dane (GD) with cervical spondylomyelopathy (CSM); N, unaffected (Normal) GD. *P < 0.05.

Fig. 5

Mean spinal cord area (SCA) and 95% confidence interval (CI) measured at the caudal aspect of the cranial vertebral body (SCA_cra), at the center of the intervertebral space (SCA_IVD) and at the cranial aspect of the caudal vertebral body (SCA_cau). CSM, Great Dane (GD) with cervical spondylomyelopathy (CSM); N, unaffected (normal) GD. *P < 0.05.

Fig. 6

Mean vertebral canal width (VCW) and 95% confidence interval (CI) measured at the caudal aspect of the cranial vertebral body (VCW_cra), at the center of the intervertebral space (VCW_IVD) and at the cranial aspect of the caudal vertebral body (VCW_cau). CSM, Great Dane (GD) with cervical spondylomyelopathy (CSM); N, unaffected (normal) GD. *P < 0.05.

Fig. 7

Mean spinal cord width (SCW) and 95% confidence interval (CI) measured at the caudal aspect of the cranial vertebral body (SCW_cra), at the center of the intervertebral space (SCW_IVD) and at the cranial aspect of the caudal vertebral body (SCW_cau). CSM, Great Dane (GD) with cervical spondylomyelopathy (CSM); N, unaffected (normal) GD. *P < 0.05.

Fig. 8

Mean right and left middle foraminal height (MFH) and 95% confidence interval (CI) measured at the center of the intervertebral space. R, right, L, left. CSM, Great Dane (GD) with cervical spondylomyelopathy (CSM); N, unaffected (normal) GD. *P < 0.05.