Functional and histopathologic evidence of laryngeal reinnervation using the spinal accessory nerve in horses.

SAN reinnervation restores laryngeal function in RLN-affected horses with mild-moderate atrophy.

This prospective cohort study evaluated selective laryngeal reinnervation using the spinal accessory nerve (SAN) as a treatment for experimentally induced recurrent laryngeal neuropathy (RLN) in five Thoroughbred mares. Following left recurrent laryngeal neurectomy, horses underwent standing surgical reinnervation using the SAN. Functional outcomes were assessed via treadmill endoscopy, ultrasonography, and electrical stimulation at multiple timepoints through 12 months post-operatively. At 12 months, mean arytenoid abduction recovered to 94% of predenervation values in four of five horses, with no statistical difference from baseline. Post-mortem examination confirmed successful SAN implantation in the cricoarytenoideus dorsalis muscle with histopathologic evidence of axonal regeneration and functional reinnervation, including fiber type grouping and increased type I fiber proportion. One horse exhibited incomplete recovery. The authors conclude that selective laryngeal reinnervation using the SAN represents a physiologically sound and effective treatment option for equine RLN in cases with mild to moderate muscle atrophy.

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