Comparison of magnetic resonance imaging with standing cervical radiographs for evaluation of vertebral canal stenosis in equine cervical stenotic myelopathy.
Authors: Janes J G, Garrett K S, McQuerry K J, Pease A P, Williams N M, Reed S M, MacLeod J N
Journal: Equine veterinary journal
Summary
# Editorial Summary Cervical stenotic myelopathy (CSM) in young Thoroughbreds remains challenging to diagnose accurately using standard lateral cervical radiographs, which provide only a sagittal (two-dimensional) view of the vertebral canal and frequently produce both false positives and false negatives when using traditional sagittal diameter ratios. Janes and colleagues compared ante-mortem standing radiographs and post-mortem MRI scans in 19 affected horses and 9 controls, measuring vertebral canal dimensions and the ratio of spinal cord area to vertebral canal area across cervical vertebrae C3–C7, then validated findings against histopathological examination of spinal cord tissue. Whilst conventional radiographic measurements showed poor correlation with actual sites of cord compression confirmed by histology, MRI-derived vertebral canal area and cord-to-canal area ratios accurately predicted stenosis location at multiple vertebral levels; notably, no meaningful differences in spinal cord dimensions themselves were observed between affected and control horses, suggesting that canal narrowing rather than cord atrophy drives clinical signs. For practitioners managing suspected CSM cases, this work demonstrates that radiography alone is insufficient for precise anatomical diagnosis, and that cross-sectional imaging capable of measuring true canal area in multiple planes substantially improves identification of compression sites—a finding with particular significance for determining prognosis and surgical candidacy once MRI or CT facilities for standing adult horses become more widely available.
Read the full abstract on PubMed
Practical Takeaways
- •Standing cervical radiographs alone are unreliable for diagnosing CSM—MRI is needed for accurate assessment of canal stenosis and spinal cord compression
- •Radiographic sagittal ratios commonly misclassify horses as stenotic or normal; use MRI to confirm diagnosis before committing to treatment or retirement decisions
- •Development of portable or field-suitable MRI/CT for adult horses would substantially improve diagnostic accuracy and clinical management of CSM cases
Key Findings
- •Lateral cervical radiographs produced multiple false positive and false negative determinations of canal stenosis compared to spinal cord histopathology
- •MRI measurements of vertebral canal area and cord-canal area ratio more accurately predicted sites of cord compression than radiographic sagittal diameter ratios
- •Vertebral canal parameters differed significantly between CSM and control horses at multiple cervical sites, while spinal cord measurements did not
- •Three-dimensional MRI assessment is superior to two-dimensional radiographic evaluation for identifying cervical canal stenosis in horses