title: Laryngeal Reinnervation Using a Split-Hypoglossal Nerve Graft in a Canine Model.
abstract: OBJECTIVE
  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.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
  
  
  METHODS
  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
  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.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston.
authors.forename: Kyle J
authors.initials: KJ
authors.lastname: Chambers
authors.affiliation: Division of Pediatric Otolaryngology, Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts.
authors.forename: Nikhila
authors.initials: N
authors.lastname: Raol
authors.affiliation: Division of Laryngology, Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts4Division of Thyroid and Parathyroid Surgery, Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts.
authors.forename: Phillip C
authors.initials: PC
authors.lastname: Song
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston.
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Randolph
authors.affiliation: Division of Pediatric Otolaryngology, Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Hartnick
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D004576:Electromyography; D005240:Feasibility Studies; D005260:Female; D007002:Hypoglossal Nerve / Q000637:transplantation*; D007828:Laryngoscopy; D010865:Pilot Projects; D061226:Recurrent Laryngeal Nerve Injuries / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D014826:Vocal Cord Paralysis / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D014827:Vocal Cords / Q000294:innervation* / Q000503:physiopathology*