HSC Section 6 Nov2016 Green Book

Reprinted by permission of Laryngoscope. 2014; 124(8):1900-1905.

The Laryngoscope V C 2014 The American Laryngological, Rhinological and Otological Society, Inc.

Effect of Duration of Denervation on Outcomes of Ansa-Recurrent Laryngeal Nerve Reinnervation

Meng Li, MD; Shicai Chen, MD; Wei Wang, MD; Donghui Chen, MD; Minhui Zhu, MD; Fei Liu, MD; Caiyun Zhang, MD; Yan Li, MD; Hongliang Zheng, MD

Objectives/Hypothesis: To investigate the efficacy of laryngeal reinnervation with ansa cervicalis among unilateral vocal fold paralysis (UVFP) patients with different denervation durations. Study Design: We retrospectively reviewed 349 consecutive UVFP cases of delayed ansa cervicalis to the recurrent laryngeal nerve (RLN) anastomosis. Potential influencing factors were analyzed in multivariable logistic regression analysis. Stratification analysis performed was aimed at one of the identified significant variables: denervation duration. Methods: Videostroboscopy, perceptual evaluation, acoustic analysis, maximum phonation time (MPT), and laryngeal electromyography (EMG) were performed preoperatively and postoperatively. Gender, age, preoperative EMG status and denervation duration were analyzed in multivariable logistic regression analysis. Stratification analysis was performed on denervation duration, which was divided into three groups according to the interval between RLN injury and reinnervation: group A, 6 to 12 months; group B, 12 to 24 months; and group C, > 24 months. Results: Age, preoperative EMG, and denervation duration were identified as significant variables in multivariable logis- tic regression analysis. Stratification analysis on denervation duration showed significant differences between group A and C and between group B and C ( P < 0.05)—but showed no significant difference between group A and B ( P > 0.05) with regard to parameters overall grade, jitter, shimmer, noise-to-harmonics ratio, MPT, and postoperative EMG. In addition, videostrobo- scopic and laryngeal EMG data, perceptual and acoustic parameters, and MPT values were significantly improved postopera- tively in each denervation duration group ( P < 0.01). Conclusions: Although delayed laryngeal reinnervation is proved valid for UVFP, surgical outcome is better if the proce- dure is performed within 2 years after nerve injury than that over 2 years. Key Words: Vocal cord paralysis, laryngeal reinnervation, ansa cervicalis, recurrent laryngeal nerve, denervation duration. Level of Evidence: 4. Laryngoscope , 124:1900–1905, 2014

INTRODUCTION Unilateral vocal fold paralysis (UVFP) is a condition commonly seen in otolaryngology clinics. The most fre- quent cause of UVFP is injury to the recurrent laryngeal nerve (RLN). 1 UVFP can present as various degrees of dysphonia and dysphagia, and has a significant impact on a patient’s quality of life. There are various surgical methods for treating UVFP. These include vocal fold injection, thyroplasty, arytenoid adduction, and laryn- geal reinnervation, which is an effective surgical proce- dure with better long-term outcomes because it restores From the Department of Otolaryngology–Head and Neck Surgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, People’s Republic of China Editor’s Note: This Manuscript was accepted for publication January 27, 2014. This work was supported by Grants 81100724, 81170899, 81070775 for science research from National Natural Science Foundation of China, and Grant 10XD1405500 from the Science and Technology Commission of Shanghai Municipality. The authors have no other finan- cial relationships, or conflicts of interest to disclose. Send correspondence to Hongliang Zheng, MD, Department of Oto- laryngology–Head and Neck Surgery, Changhai Hospital, Second Mili- tary Medical University, Shanghai 200433, People’s Republic of China. E-mail: zheng_hl2004@163.com

neural connections to laryngeal muscles and thus main- tains the bulk, tension, and position of the paralyzed vocal fold. 2,3 Our previous large-scale study, as well as reports from other researchers, demonstrated satisfac- tory or good voice outcomes in patients who underwent ansa cervicalis–RLN anastomosis. 4–6 Experimental studies have shown that reinnerva- tion surgery can restore laryngeal function with excel- lent results when performed immediately following nerve resection. 7,8 However, in clinical practice, there is usually a considerable delay between RLN injury and presentation for reinnervation surgery. In addition, 6 to 12 months are usually allowed for possible spontaneous recovery of the paralyzed vocal fold or compensation from the contralateral vocal fold, even when UVFP is diagnosed early. Surgical intervention is considered only in cases with unsatisfactory spontaneous recovery. At present, there are no definitive clinical data regarding the longest allowable period between the onset of RLN injury and nerve reconstruction to achieve functional recovery of the adductor muscle. In the present study, we analyzed several potential influencing factors of laryngeal reinnervation, including gender, age of patients, preoperative maximal voluntary motor-unit recruitment (VMUR) of laryngeal muscles,

DOI: 10.1002/lary.24623

Laryngoscope 124: August 2014

Li et al.: Denervated Duration on Reinnervation for UVFP

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