E54 - Computed Tomographic Myelography in Horses with Cervical Vertebral Compressive Myelopathy

Abstract:
Background: Radiographic myelography underestimates the presence of CVCM, mainly due to lack of three-dimensional assessment of the spinal cord, which is possible using CT myelography.
Hypothesis/Objectives: Establish morphometric measures of cervical spine structures in sound and CVCM horses. We hypothesize that focal cervical vertebral canal and spinal cord dimensions are smaller in horses with CVCM and that CT myelography detects fewer and sometimes other compressed sites.

Animals: Five neurologically sound and 9 CVCM horses were used. Hospital population. IACUC approval through protocol 16-6674AA.

Methods: Case-control study from hospital-based population. All horses underwent a neurologic examination, radiographic and CT myelography, and post-mortem evaluation. Myelographic dorsal column and dural and spinal cord height and areas were compared between sound and CVCM horses, and between compressed and non-compressed sites.

Results: There were no sites of spinal cord compression identified via CT myelography that had not been detected by radiographic myelography. Spinal cord and dural areas were consistently smaller in CVCM horses, but these were statistically significant only for C5-C6 (p=0.02) and C6-C7 (p=0.04). The ratio of full myelographic area at the intervertebral space to vertebral body height of either cranial or caudal body were significantly smaller in the CVCM group (p< 0.001).

Conclusions: CT-myelography was not superior to radiographic myelography for diagnosing CVCM in this population. CVCM horses had smaller spinal cords than control horses. Using a ratio of full myelographic area compared to vertebral body height is useful for diagnosing spinal cord compression.