Airway stenosis following immediate bilateral recurrent laryngeal nerve reconstruction: report of two cases successfully treated with laser submucosal intermediate transverse resection of the arytenoid cartilage

Introduction

Recurrent laryngeal nerve (RLN) injury remains one of the most serious complications of thyroid surgery. Unilateral RLN paralysis may cause dysphonia and swallowing dysfunction, whereas bilateral RLN paralysis can result in life-threatening airway compromise. Current guidelines recommend the use of intraoperative neural monitoring (IONM) to aid in RLN preservation during thyroid surgery and consideration of a staged surgical approach when loss of signal (LOS) is detected on the first side (1).

Immediate RLN reconstruction is widely accepted as an effective strategy for restoring voice quality and preventing vocal fold atrophy after nerve injury and is strongly recommended when RLN resection is unavoidable (2). However, the available literature has focused primarily on unilateral nerve injury, and little attention has been paid to bilateral RLN reconstruction. Because regenerating nerve fibers may undergo misdirected reinnervation, successful nerve regeneration does not necessarily restore normal vocal fold motion. In bilateral cases, synkinetic reinnervation may contribute to airway stenosis by maintaining both vocal folds in a median or paramedian position.

We report two cases of airway stenosis following immediate bilateral RLN reconstruction performed during surgery for benign thyroid tumors. Both patients subsequently underwent laser submucosal intermediate transverse resection of the arytenoid cartilage (LSITRA) to enlarge the posterior glottis. These cases highlight a potentially preventable complication of bilateral RLN reconstruction and emphasize the importance of staged surgical decision-making when bilateral nerve injury is a concern. We present this article in accordance with the CARE reporting checklist (available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0257/rc).

Case presentation

Ethical statement

All procedures performed in this study were in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Ethics Committee of Toho University Medical Center Omori Hospital (No. M24227). Written informed consent was obtained from the patients for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal. In this case report, the research information was publicly available on a website, with the opportunity to opt out.

Patients

Case 1: 53-year-old female

The patient underwent total thyroidectomy at the age of 41 years for a large thyroid tumor causing tracheal compression and suspected to be an adenomatous goiter. Histopathological examination of the resected specimen subsequently confirmed adenomatous goiter. The procedure was performed with IONM. During surgery, LOS was detected bilaterally. Subsequent exploration revealed transection of both RLNs, and immediate bilateral nerve reconstruction using end-to-end anastomosis was performed. A tracheostomy was also created intraoperatively.

The patient subsequently consulted several hospitals for tracheostomy closure and was eventually referred to our institution because decannulation was considered difficult due to severe glottic stenosis. Laryngeal findings at presentation are shown in Figure 1. Endoscopic examination revealed both vocal folds fixed in the median position. Laryngeal electromyography demonstrated nerve misinnervation (Figure 2). Respiratory evaluation revealed upper airway obstruction, with a peak flow of 27% of the predicted value and dyspnea on the modified Borg scale. Voice and swallowing functions were relatively well preserved.

Figure 1 Examination results and laryngeal findings pre- and post-surgery. ¹, modified Borg scale: a subjective breathlessness scale ranging from 0 (no symptoms) to 10 (very severe), marked by the patient on a vertical line with labeled anchor points. ², PEF-% prediction: percentage of the measured peak expiratory flow compared to the predicted value; used as an index for upper airway stenosis to evaluate treatment effectiveness. ³, EAT-10: a standardized questionnaire for evaluating swallowing function. EAT-10, Eating Assessment Tool; F, female; MFR, mean flow rate; MPT, maximum phonation time; PEF, peak expiratory flow; VHI, Voice Handicap Index; y, years.

Figure 2 Laryngeal electromyography of the left thyroarytenoid muscle in cases 1 and 2. Both patients demonstrated evidence of nerve reinnervation. Interference wave activity increased during inspiration (*) and decreased during phonation, indicating misinnervation from the reconstructed nerve. Arrows indicate the sound produced by the opening and closing of the speech valve on the tracheostomy cannula.

More than 1 year had elapsed since the onset of paralysis, and spontaneous recovery of functional vocal fold movement was considered unlikely; therefore, surgical intervention was planned (3). The LSITRA technique (4) was performed on the right side under general anesthesia (Figure 3). Intraoperative traction-mobility test confirmed normal mobility of the arytenoid cartilage and absence of cricoarytenoid joint fixation, supporting a neurogenic rather than mechanical cause of vocal fold immobility (4).

Figure 3 LSITRA technique. (A) Laryngeal findings during surgery. Asterisk: arytenoid cartilage. Double circle: cricoid cartilage. (B) Vaporize the mucosa of the arytenoid area using a laser to expose the arytenoid cartilage. (C) Resection of the middle part of the arytenoid cartilage. (D) Suture the remaining mucosa and enlarge the posterior glottis, which allows more airflow. Top: schematic; bottom: laryngeal findings during surgery. LSITRA, laser submucosal intermediate transverse resection of the arytenoid cartilage.

Postoperative pulmonary function test demonstrated improvement of the peak flow to 46% of the predicted value. Respiratory symptoms improved, and tracheostomy closure was achieved four months later. During more than 1 year of follow-up after decannulation, no clinical or endoscopic evidence of restenosis was observed. Voice and swallowing functions showed only minimal postoperative deterioration.

Case 2: 53-year-old female

The patient underwent surgery at the age of 52 years for a large thyroid tumor extending into the upper mediastinum. Preoperative fine-needle aspiration cytology suggested a benign lesion, and surgery was performed based on a clinical diagnosis of adenomatous goiter. Histopathological examination of the resected specimen subsequently confirmed adenomatous goiter. The procedure was performed with IONM. During surgery, bilateral LOS was detected, and subsequent exploration revealed transection of both RLNs. Immediate bilateral nerve reconstruction using end-to-end anastomosis was therefore performed. A tracheostomy was also created intraoperatively.

Postoperatively, the airway was initially considered adequate, and the tracheostomy was closed. However, progressive glottic stenosis subsequently developed, resulting in dyspnea and the need for repeat tracheostomy. The patient was referred to our institution because decannulation was considered difficult due to persistent glottic stenosis, and she wished to undergo tracheostomy closure.

Laryngeal findings at presentation are shown in Figure 1. Endoscopic examination revealed both vocal folds fixed in the median position. Laryngeal electromyography demonstrated nerve misinnervation (Figure 2). Respiratory evaluation revealed upper airway obstruction, with a peak flow of 55% of the predicted value and subjective dyspnea on the modified Borg scale. Voice and swallowing functions were relatively well preserved.

More than 1 year had elapsed since the onset of paralysis, and spontaneous recovery of functional vocal fold movement was considered unlikely; therefore, surgical intervention was planned. Under general anesthesia, LSITRA was performed on the left vocal fold. Intraoperative traction-mobility test confirmed normal mobility of the arytenoid cartilage and absence of cricoarytenoid joint fixation, supporting a neurogenic rather than mechanical cause of vocal fold immobility.

Postoperative pulmonary function test demonstrated improvement of the peak flow to 87% of the predicted value. Respiratory symptoms improved, and tracheostomy closure was achieved four months later. During more than three years of follow-up after decannulation, no clinical or endoscopic evidence of restenosis was observed. Voice function showed only minimal postoperative deterioration, and no adverse effects on swallowing function were identified.

Discussion

Immediate intraoperative RLN reconstruction

The primary functions of the larynx include respiration, swallowing, and phonation. In unilateral vocal fold paralysis, airway patency is generally maintained, though swallowing dysfunction and hoarseness may occur. However, when both vocal folds are impaired and fixed at the midline, severe airway stenosis can develop.

With recent advances, intraoperative nerve stimulators allow for highly accurate monitoring of the RLN. However, it remains unclear whether such monitoring significantly reduces the incidence of nerve injury (5). The incidence of unilateral RLN paralysis in thyroid surgery is reported to be approximately 10% (6,7). Although the incidence of bilateral RLN paralysis has not been widely reported, paralysis is reported to be permanent in approximately 45% of such cases (1).

Since the report by Miyauchi et al., several studies have documented the benefits of immediate RLN reconstruction (8). A review of these studies suggests that although evidence remains limited, the procedure to be effective (9). In addition, the guidelines established by the Japanese Society of Endocrine Surgery strongly recommend immediate reconstruction when nerve resection is performed (2). However, these guidelines and articles do not address management when both RLNs are simultaneously resected.

The primary goal of RLN reconstruction is not to restore vocal fold movement but rather to position the paralyzed vocal fold at the midline and maintain or augment its bulk. In unilateral vocal fold paralysis, this strategy improves postoperative voice and swallowing. However, bilateral nerve reconstruction, when successful, may result in midline fixation of both folds and subsequent airway stenosis.

In both cases reported here, total thyroidectomy and bilateral nerve reconstruction were performed in a single stage, resulting in bilateral midline fixation of the vocal folds and the need for tracheotomy. In both cases, laryngeal electromyography demonstrated reinnervation with synkinetic activity, characterized by increased thyroarytenoid muscle activity during inspiration and reduced activity during phonation. In addition, intraoperative traction-mobility test confirmed normal arytenoid mobility without evidence of cricoarytenoid joint fixation. These findings supported neurogenic bilateral vocal fold immobility caused by misinnervation after RLN reconstruction rather than mechanical restriction of vocal fold movement. The mechanism underlying airway stenosis after bilateral RLN reconstruction is likely related to misdirected reinnervation. The RLN trunk contains motor fibers to both the posterior cricoarytenoid muscle, the sole abductor of the vocal fold, and the adductor muscles. Following nerve transection and reconstruction, regenerating axons may not reconnect with their original target muscles. Instead, aberrant regeneration can result in synkinetic reinnervation, in which abductor and adductor muscles are activated simultaneously. Previous electromyographic and experimental studies have demonstrated that such misdirected reinnervation may produce paradoxical vocal fold adduction during inspiration and airway obstruction. In bilateral cases, this phenomenon may maintain both vocal folds in a median or paramedian position despite successful nerve regeneration, resulting in clinically significant airway stenosis (10).

The limitations of this paper include the small number of cases (two cases), and the fact that we were unable to mention the percentage of cases of airway stenosis among patients undergoing bilateral nerve reconstruction. However, considering that airway stenosis is a fatal complication and that both tumors were benign, a two-stage approach would have been more appropriate. Once LOS is observed on one side, surgery should be halted; the outcome of nerve injury should be assessed postoperatively and contralateral surgery considered at a later stage (1).

Surgery for glottic stenosis due to bilateral RLN paralysis

The most common cause of bilateral vocal fold immobility accompanied by airway stenosis is bilateral RLN paralysis (11). Vocal fold movement disorders due to nerve paralysis do not spontaneously recover after a certain period, making surgical treatment an option. Surgical procedures include the laser excision of the arytenoid cartilage with or without partial vocal fold resection (12) and lateral fixation of the vocal fold with nylon sutures (13). These surgeries enlarge the glottis and secure the airway. Functions of the larynx include respiration, swallowing, and phonation; of these, respiration is a vital function directly related to maintaining life, and thus, a significant decline in postoperative voice and swallowing function has been considered unavoidable in order to secure the airway. These surgeries enlarge the glottis and secure the airway. However, arytenoidectomy may adversely affect voice quality and swallowing function because of irreversible alteration of the laryngeal framework. Similarly, vocal fold lateralization procedures may result in persistent glottic insufficiency and dysphonia. Therefore, a surgical approach that balances airway enlargement with preservation of laryngeal function is desirable.

Therefore, we focused on the fact that much of the airflow passes through the posterior glottis (14) and devised LSITRA with the aim of minimizing the decline in vocal and swallowing function. LSITRA is a surgical procedure that vaporizes the intermediate portion of one arytenoid cartilage into the submucosa and is expected to have the following three effects. First, the posterior glottis expands as the middle portion of the arytenoid cartilage is vaporized. Furthermore, the persistent adduction due to misinnervation weakens, causing slight abduction of the vocal fold. These processes resolve airway stenosis. Second, by preserving the arytenoid ridge, food and drink can be prevented from entering the laryngeal vestibule, reducing the risk of aspiration. Third, by preserving the vocal fold process of the arytenoid cartilage, the decrease in vocal fold tension is reduced, preventing the worsening of voice disorders.

This report involves only two cases, which limits its ability to demonstrate the effectiveness of this surgical technique. In conditions like posterior glottic stenosis, where nerve health is preserved, vocal fold movement can be restored by removing the scar tissue restricting movement (15). However, vocal fold movement disorders caused by nerve paralysis do not spontaneously recover after a certain period. Therefore, to secure the airway, it is necessary to manipulate the normal structure, as done in this surgical procedure. In both cases reported herein, this procedure allowed for the closure of the tracheostomy, minimizing the decline in voice and swallowing function.

Conclusions

We report two cases of airway stenosis following immediate bilateral RLN reconstruction during total thyroidectomy. The LSITRA technique for bilateral RLN paralysis was an effective procedure with minimal adverse effects on voice and swallowing function. Although nerve reconstruction offers functional benefits, bilateral reconstruction should be avoided due to the risk of airway stenosis. This recommendation should be clearly reflected in future clinical guidelines and disseminated among endocrine surgeons.

Acknowledgments

The authors thank all members of the Department of Otolaryngology for their support in the management of these patients. This work was presented in part at the 38th Annual Meeting of the Japan Association of Endocrine Surgery (2026, Osaka, Japan).

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0257/rc

Peer Review File: Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0257/prf

Funding: This work was supported by the Japan Agency for Medical Research and Development (AMED) (No. JP26hk0102111s0101).

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0257/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Ethics Committee of Toho University Medical Center Omori Hospital (No. M24227). Written informed consent was obtained from the patients for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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