Retrospective radiographic myelogram measurements and long-term outcomes in horses undergoing cervical interbody fusion surgery: 22 cases.
Authors: England Devon, Newsom Lauren, White Constance, McKenzie Erica
Journal: PloS one
Summary
# Editorial Summary Cervical interbody fusion via Kerf-cut cylinder technique is increasingly used to stabilise horses with spinal ataxia, yet the radiographic myelography measurements guiding surgical site selection—dorsal contrast column reduction (DCCR) and dural diameter reduction (DDR)—have never been systematically validated. This retrospective analysis of 22 horses operated between 2008 and 2022 compared how well these two measurement criteria correlated with each other and with the sites ultimately selected for surgery, whilst also tracking long-term articular process joint (APJ) changes and complications. DCCR proved remarkably unremarkable across nearly all cervical articulations, whereas DDR met reduction criteria at over 50% of articulations in flexion; critically, neither measure reliably distinguished operated from non-operated sites except at C6-7, and the two measurements showed poor correlation at most locations regardless of neck position. Long-term radiographic follow-up (>18 months post-surgery) revealed only mild, inconsistent APJ opacity reduction without predictable changes in APJ height or area ratios, and complication rates were high, particularly laryngeal hemiplegia. These findings highlight substantial uncertainty in current myelographic diagnostic criteria for site selection and suggest that practitioners should exercise considerable caution in relying on DCCR and DDR measurements alone—particularly outside the C6-7 articulation—whilst noting that cervical stabilisation carries meaningful surgical risks that warrant thorough discussion with clients.
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Practical Takeaways
- •Myelographic measurements (DCCR and DDR) alone are unreliable for selecting cervical fusion surgery sites in horses with spinal ataxia—consider additional diagnostic information and clinical signs
- •Be aware that DCCR and DDR can yield conflicting results at the same location; C6-7 appears more reliably identified than other sites
- •Expect a high complication rate from cervical interbody fusion surgery, particularly laryngeal hemiplegia; counsel owners accordingly and monitor post-operative laryngeal function closely
Key Findings
- •Dorsal contrast column reduction (DCCR) was unremarkable at nearly all articulations, while dural diameter reduction (DDR) met reduction criteria at >50% of articulations in flexed position
- •DCCR and DDR did not reliably distinguish operated from non-operated sites except at C6-7 articulation in neutral and extended positions
- •The two measurement techniques were poorly correlated at most sites and positions, suggesting conflicting diagnostic classifications
- •High incidence of laryngeal hemiplegia occurred as a surgical complication; radiographic follow-up showed mild APJ opacity reduction without consistent decreases in APJ height or area ratios