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Laryngeal Reinnervation Using a Split-Hypoglossal Nerve Graft in a Canine Model
Kyle J Chambers1, Nikhila Raol2, Phillip C Song3
1Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston.
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.
