Recurrent laryngeal nerve transection in mice results in translational upper airway dysfunction

• Published in: Journal of comparative neurology (1911) 2020-03, Vol.528 (4), p.574-596
• Main Authors: Haney, Megan M., Hamad, Ali, Woldu, Henok G., Ciucci, Michelle, Nichols, Nicole, Bunyak, Filiz, Lever, Teresa E.
• Format: Article
• Language: English
• Subjects: animal model; Apoptosis; Cell death; dysphagia; dysphonia; dyspnea; Endoscopy; Immunohistochemistry; Nucleus ambiguus; Paralysis; Recovery of function; recurrent laryngeal nerve injury; Regeneration; Respiration; Respiratory function; Respiratory tract; RRID:AB_141708; RRID:AB_2532109; Surgery; Therapeutic applications; Translation; unilateral vocal‐fold paralysis
• ISSN: 0021-9967; 1096-9861
• DOI: 10.1002/cne.24774

The recurrent laryngeal nerve (RLN) is responsible for normal vocal‐fold (VF) movement, and is at risk for iatrogenic injury during anterior neck surgical procedures in human patients. Injury, resulting in VF paralysis, may contribute to subsequent swallowing, voice, and respiratory dysfunction. Unfortunately, treatment for RLN injury does little to restore physiologic function of the VFs. Thus, we sought to create a mouse model with translational functional outcomes to further investigate RLN regeneration and potential therapeutic interventions. To do so, we performed ventral neck surgery in 21 C57BL/6J male mice, divided into two groups: Unilateral RLN Transection (n = 11) and Sham Injury (n = 10). Mice underwent behavioral assays to determine upper airway function at multiple time points prior to and following surgery. Transoral endoscopy, videofluoroscopy, ultrasonic vocalizations, and whole‐body plethysmography were used to assess VF motion, swallow function, vocal function, and respiratory function, respectively. Affected outcome metrics, such as VF motion correlation, intervocalization interval, and peak inspiratory flow were identified to increase the translational potential of this model. Additionally, immunohistochemistry was used to investigate neuronal cell death in the nucleus ambiguus. Results revealed that RLN transection created ipsilateral VF paralysis that did not recover by 13 weeks postsurgery. Furthermore, there was evidence of significant vocal and respiratory dysfunction in the RLN transection group, but not the sham injury group. No significant differences in swallow function or neuronal cell death were found between the two groups. In conclusion, our mouse model of RLN injury provides several novel functional outcome measures to increase the translational potential of findings in preclinical animal studies. We will use this model and behavioral assays to assess various treatment options in future studies. The recurrent laryngeal nerve (RLN) is responsible for vocal‐fold (VF) movement, and is at risk for iatrogenic injury during anterior neck surgical procedures in human patients. Injury, resulting in VF paralysis, may contribute to subsequent swallowing, voice, and respiratory dysfunction. Treatment does little to restore physiologic function of the VFs. Thus, we sought to create a mouse model with translational functional outcomes to investigate RLN regeneration and potential therapeutic interventions. We used our custom laryngosc