In vivo diffusion characteristics following perineural injection of the deep branch of the lateral plantar nerve with mepivacaine or iohexol in horses.
Authors: Contino E K, King M R, Valdés-Martínez A, McIlwraith C W
Journal: Equine veterinary journal
Summary
# Editorial Summary Proximal suspensory ligament injury remains a significant diagnostic challenge in sport horses, as traditional diagnostic blocks lack the anatomical specificity required to confidently isolate pain originating from this region. Contino and colleagues investigated the feasibility of perineural analgesia targeting the deep branch of the lateral plantar nerve (DBLPN) as a more precise alternative, using mepivacaine combined with iohexol contrast medium to visualise diffusion patterns in cadaveric and live horses. The contrast medium demonstrated predictable spread from the injection site to anaesthetise the deep branch reliably, validating the technical approach; however, the study also revealed variable diffusion patterns between individuals, with some spread extending beyond the target nerve. For practitioners employing DBLPN blocks in the field, these findings highlight both the potential utility of this technique for diagnosing proximal suspensory pathology and the importance of recognising that analgesia may extend to adjacent structures—meaning a positive response doesn't guarantee the suspensory ligament is the sole pain source. Understanding these anatomical variables should inform interpretation of diagnostic blocks and guide case selection, particularly when differentiating between proximal suspensory and collateral ligament injuries in the tarsal region.
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Practical Takeaways
- •Perineural analgesia of the DBLPN offers a more specific diagnostic approach than traditional regional anesthesia for isolating proximal suspensory ligament pain in sport horses
- •This technique may improve diagnostic accuracy when evaluating hindlimb lameness associated with proximal suspensory desmopathy
- •Understanding diffusion patterns of local anesthetics in this nerve block helps optimize injection technique and clinical application
Key Findings
- •Perineural analgesia of the deep branch of the lateral plantar nerve was evaluated in vivo for the first time to improve diagnostic specificity
- •The study compared diffusion characteristics of mepivacaine and iohexol following perineural injection of the DBLPN
- •The technique addresses limitations of existing diagnostic analgesia methods that lack specificity for proximal suspensory ligament pathology