Transoesophageal ultrasound and computer tomographic assessment of the equine cricoarytenoid dorsalis muscle: Relationship between muscle geometry and exercising laryngeal function.
Authors: Kenny M, Cercone M, Rawlinson J J, Ducharme N G, Bookbinder L, Thompson M, Cheetham J
Journal: Equine veterinary journal
Summary
# Editorial Summary Recurrent laryngeal neuropathy remains a significant performance-limiting condition in horses, yet early detection through functional assessment alone is challenging. Kenny and colleagues investigated two imaging techniques—transoesophageal ultrasound (TEU) and computed tomography (CT) with multiplanar reconstruction—to characterise the cricoarytenoid dorsalis (CAD) muscle and establish whether structural changes correlate with laryngeal dysfunction. Using CT volumetric reconstruction validated against post-mortem specimens (R² = 0.77) and TEU assessment in 112 horses spanning the spectrum of RLN severity, the researchers demonstrated that reduced left:right CAD muscle thickness ratios detected via TEU correlated with increasing disease severity. These non-invasive imaging modalities now offer practitioners an objective, quantifiable method to monitor CAD muscle atrophy in affected horses and, critically, to objectively track therapeutic responses to emerging restorative treatments such as nerve-muscle pedicle grafts, nerve anastomosis, and functional electrical stimulation—interventions previously lacking reliable outcome measures. For clinicians managing RLN cases, these techniques represent a significant advance in diagnostic precision and post-surgical evaluation beyond endoscopic grading alone.
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Practical Takeaways
- •TEU and CT imaging can detect and quantify laryngeal muscle changes associated with RLN, enabling earlier diagnosis of this performance-limiting condition
- •CAD muscle geometry measurements provide objective markers to monitor recovery following surgical interventions for RLN
- •These non-invasive imaging techniques offer an alternative to endoscopy for assessing laryngeal function in horses with suspected or confirmed RLN
Key Findings
- •Transoesophageal ultrasound successfully imaged cricoarytenoid dorsalis muscles with lower left:right thickness ratios correlating with increasing RLN disease severity
- •CT-based muscle volume reconstruction correlated very closely with ex vivo muscle volume (R² = 0.77)
- •A relationship between TEU measurements of CAD geometry and laryngeal function was established
- •Both imaging modalities can be used to track CAD muscle response to restorative surgical treatments including nerve muscle pedicle graft, nerve anastomosis, and functional electrical stimulation