Objective

Laryngeal reinnervation is the preferred treatment for vocal fold paralysis, with superior voice outcomes thought to result from the prevention of long-term denervation atrophy. In cases where primary nerve anastomosis is not feasible, such as after oncologic resection or delayed nerve injury, interposition nerve grafts are often used to bridge the gap between nerve stumps. Despite their widespread use in facial reinnervation, the efficacy of interposition grafts, particularly in laryngeal reinnervation, is poorly characterized. This study assesses effects of autologous interposition graft length for laryngeal reinnervation.

Methods

A rabbit model of acute unilateral recurrent laryngeal nerve (RLN) paralysis followed by immediate reinnervation using an autologous ansa cervicalis nerve interposition graft (of lengths 0, 2, 4, 6cm) was used. Rabbits were monitored for 4 moths postoperatively, and the RLN with interposition graft and bilateral thyroarytenoid (TA) muscles were harvested. The degree of axonal transmission across the proximal nerve, interposition graft, and the distal nerve was measured using lipid staining. TA myofiber area and neuromuscular junction quality, as characterized by innervation and morphology, were measured using hematoxylin-eosin and immunohistochemical staining, respectively.

Results

There is no statistical difference in myofiber area in the TA between experimentals and controls for each graft length or between graft lengths using a linear mixed effects model. All TA samples have also been stained and imaged for NMJs, and analysis of NMJs for innervation and motor endplate morphology are ongoing. RLN staining is still ongoing as well.

Conclusions

We evaluated the impact of interposition graft length on laryngeal reinnervation. Histologic analysis summarizes axonal transmission and neuromuscular junction recovery. Characterization of graft-mediated reinnervation provides foundational data for optimizing future nerve reconstruction strategies in the larynx and beyond.