Computed tomographic myelography of the cranial cervical vertebral column in unaffected Warmblood horses - comparison of transverse vertebral ratios in the flexed and neutral cranial cervical vertebral column.

BACKGROUND

Computed tomographic myelography (CTM) is diagnostic for extradural spinal cord compression but knowledge about vertebral ratios from transverse images in flexion and normal position of unaffected horses is lacking.

OBJECTIVES

To compare the ratios of the cross-sectional areas (CSAs) of the spinal cord, the vertebral canal and of the contrast enhanced dural tube on transverse CTM images at C3-C4 in neutral and flexed positions in unaffected Warmbloods.

METHODS

CTM was performed in 13 neurologically unaffected Warmbloods in neutral and flexed cervical vertebral column positions. Ratios were calculated at intervertebral (inter1-3) and intravertebral (cranial, middle, caudal) sites. The cord canal area ratio (CCAR = CSA spinal cord / CSA vertebral canal), the dural canal area ratios (DCAR = CSA contrast enhanced dural tube / CSA vertebral canal) and the cord dural area ratios (CDAR = CSA spinal cord / CSA contrast enhanced dural tube) were calculated and compared between different cervical positions.

RESULTS

DCAR decreased significantly (p < 0.05) in the flexed compared to the neutral position. Reductions were intravertebral at the cranial and caudal sites of C3 and C4. At the intervertebral sites, there was a significant decrease at inter1 and inter2. CDAR increased significantly (p < 0.05) at all intervertebral locations (inter 1-3) in the flexed cervical vertebral column compared to the neutral position.

CONCLUSIONS

Flexion of the cervical vertebral column led to a decrease of the DCAR and an increase of the CDAR at the intervertebral sites in unaffected Warmbloods.