Laryngeal Reinnervation Using a Split-Hypoglossal Nerve Graft in a Canine Model.

IMPORTANCE Vocal fold immobility following injury to the recurrent laryngeal nerve (RLN) may lead to substantial morbidity. A reinnervation treatment strategy offers several theoretical benefits over static treatment options. This study evaluates the robustness of reinnervation of the larynx using a split-hypoglossal nerve graft in an animal model, with outcomes assessed by independent blinded review. OBJECTIVES To assess whether a full-hypoglossal nerve graft to the RLN after RLN section can provide return of dynamic vocal fold motion in a canine model, and to validate that a split-hypoglossal nerve graft to the RLN may also provide dynamic vocal fold motion to rehabilitate laryngeal function in a canine model. DESIGN, SETTING, AND SUBJECTS A pilot animal study to assess the feasibility and morbidity of laryngeal reinnervation following RLN injury with an end-to-end full-hypoglossal or split-hypoglossal nerve graft was performed at an animal care and research facility in 10 adult female dogs. The study dates were January to July 2013. INTERVENTIONS We performed full-hypoglossal (full XII group [n = 5]) and split-hypoglossal (split XII group [n = 5]) nerve grafts to the RLN in a canine model following RLN section. MAIN OUTCOMES AND MEASURES Morbidity was evaluated through scored feeding observation. Laryngeal function was assessed by video laryngoscopy and evoked laryngeal electromyography was performed at baseline and 6 months after surgery. Video laryngoscopy was graded by independent reviewers blinded to study intervention. RESULTS No clinically significant morbidity was identified after surgery. On review of video laryngoscopy, all 5 animals in the full XII group and all 5 animals in the split XII group demonstrated vocal fold motion by at least 1 independent reviewer. All 3 reviewers agreed on motion in 1 of 5 animals in the full XII group and in 1 of 5 animals in the split XII group. Stimulation of the hypoglossal nerve demonstrated neural connection on evoked laryngeal electromyography in all animals at 6 months. CONCLUSIONS AND RELEVANCE This study confirms that a full-hypoglossal or split-hypoglossal nerve graft may restore vocal fold motion, without significant functional morbidity, following RLN section in a canine model.