Intraoperative recurrent laryngeal nerve monitoring: a useful method for patients with esophageal cancer

Recurrent Laryngeal Nerve Intraoperative Neuromonitoring Indications in Non-Thyroid and Non-Parathyroid Surgery

Introperative nerve monitoring (IONM) of the recurrent laryngeal nerve (RLN) is a well-established technique to aid in thyroid/parathyroid surgery. However, there is little evidence to support its use in non-thyroid or non-parathyroid surgery. The aim of this paper was to review the current evidence regarding the use of IONM in non-thyroid/non-parathyroid surgery in the head and neck and thorax. A literature search was performed from their inception up to January 2024, including the term "recurrent laryngeal nerve monitoring". IONM in non-thyroid/non-parathyroid surgery has mainly been previously described in oesophageal surgery and in tracheal resections. However, there is little published evidence on the role of IONM with other resections in the vicinity of the RLN. Current evidence is low-level for the use of RLN IONM in non-thyroid/non-parathyroid surgery. However, clinicians should consider its use in surgery for pathologies where the RLN is exposed and could be injured.

Intraoperative Nerve Monitoring during Minimally Invasive Esophagectomy and 3-Field Lymphadenectomy: Safety, Efficacy, and Feasibility

Background

The objective of this study was to demonstrate the safety, efficacy, and feasibility of intraoperative monitoring of the recurrent laryngeal nerves during thoracoscopic and robotic 3-field esophagectomy.

Methods

This retrospective analysis details our initial experience using intraoperative nerve monitoring (IONM) during minimally invasive 3-field esophagectomy. Data were obtained from a prospectively maintained database and electronic medical records. The study included all patients who underwent minimally invasive (video-assisted thoracic surgery/robotic) transthoracic esophagectomy with neck anastomosis. The patients were divided into those who underwent IONM during the study period and a historical cohort who underwent 3-field esophagectomy without IONM at the same institution. Appropriate statistical tests were used to compare the 2 groups.

Results

Twenty-four patients underwent nerve monitoring during minimally invasive 3-field esophagectomy. Of these, 15 patients underwent thoraco-laparoscopic operation, while 9 received a robot-assisted procedure. In the immediate postoperative period, 8 of 24 patients (33.3%) experienced vocal cord paralysis. Relative to a historical cohort from the same institution, who were treated with surgery without nerve monitoring in the preceding 5 years, a 26% reduction was observed in the nerve paralysis rate (p=0.08). On follow-up, 6 of the 8 patients with vocal cord paralysis reported a return to normal vocal function. Additionally, patients who underwent IONM exhibited a higher nodal yield and a decreased frequency of tracheostomy and bronchoscopy.

Conclusion

The use of IONM during minimally invasive 3-field esophagectomy is safe and feasible. This technique has the potential to decrease the incidence of recurrent nerve palsy and increase nodal yield.

Application of Intraoperative Neuromonitoring (IONM) of the Recurrent Laryngeal Nerve during Esophagectomy: A Systematic Review and Meta-Analysis

BACKGROUND

recurrent laryngeal nerve palsy (RLNP) is a common and severe complication of esophagectomy in esophageal cancer (EC). Several studies explored the application of intraoperative neuromonitoring (IONM) in esophagectomy to prevent RLNP. The purpose of this study was to conduct a systematic review and meta-analysis to evaluate the value of IONM in esophagectomy for EC.

METHODS

an electronic of the literature using Google Scholar, PubMed, Embase, and Web of Science (data up to October 2022) was conducted and screened to compare IONM-assisted and conventional non-IONM-assisted esophagectomy. RLNP, the number of mediastinal lymph nodes (LN) dissected, aspiration, pneumonia, chylothorax, anastomotic leakage, the number of total LN dissected, postoperative hospital stay and total operation time were evaluated using Review Manager 5.4.1.

RESULT

ten studies were ultimately included, with a total of 949 patients from one randomized controlled trial and nine retrospective case-control studies in the meta-analysis. The present study demonstrated that IONM reduced the incidence of RLNP(Odds Ratio (OR) 0.37, 95% Confidence Interval (CI) 0.26-0.52) and pneumonia (OR 0.58, 95%CI 0.41-0.82) and was associated with more mediastinal LN dissected (Weighted Mean Difference (WMD) 4.75, 95%CI 3.02-6.48) and total mediastinal LN dissected (WMD 5.47, 95%CI 0.39-10.56). In addition, IONM does not increase the incidence of aspiration (OR 0.4, 95%CI 0.07-2.51), chylothorax (OR 0.55, 95%CI 0.17-1.76), and anastomotic leakage (OR 0.78, 95%CI 0.48-1.27) and does not increase the total operative time (WMD -12.33, 95%CI -33.94-9.28) or postoperative hospital stay (WMD -2.07 95%CI -6.61-2.46) after esophagectomy.

CONCLUSION

IONM showed advantages for preventing RLNP and pneumonia and was associated with more mediastinal and total LN dissected in esophagectomy. IONM should be recommended for esophagectomy.

Continuous Recurrent Laryngeal Nerve Monitoring During Single-Port Mediastinoscopic Radical Esophagectomy for Esophageal Cancer

BACKGROUND

Although single-port mediastinoscopic radical esophagectomy is ultimate minimally invasive surgery for esophageal cancer without thoracotomy or the thoracoscopic approach, the high incidence of recurrent laryngeal nerve (RLN) palsy remains a pivotal clinical issue.

METHODS

This study included 41 patients who underwent single-port mediastinoscopic radical esophagectomy with mediastinal lymphadenectomy between September 2014 and March 2022. Among these, continuous nerve monitoring (CNM) for RLN was done in 25 patients (CNM group), while the remaining 16 patients underwent without CNM (non-CNM group). Clinical benefits of CNM for RLN were evaluated.

RESULTS

The overall incidence of postoperative RLN palsy was 14.6% (6/41). The CNM group showed a significantly lower incidence of postoperative RLN palsy as compared to the non-CNM group (P = 0.026: CNM vs. non-CRNM: 4.0% (1/25) vs. 31.2% (5/16)). The CNM group had a lower incidence of postoperative pneumoniae (CNM vs. non-CNM: 4.0% (1/25) vs. 18.8% (3/16)) and shorter days of postoperative hospital stay (CNM vs. non-CNM: 13 days vs. 41 days). Multivariate analysis revealed that the CNM use (odds ratio 0.07; 95% CI 0.05-0.98) was an independent factor avoiding postoperative RLN palsy.

CONCLUSION

The CNM for RLN contributes to a remarkable reduction in the risk of postoperative RLN palsy and improvement in outcomes in single-port mediastinoscopic radical esophagectomy.

Clinical Outcome of Intraoperative Recurrent Laryngeal Nerve Monitoring during Thoracoscopic Esophagectomy and Mediastinal Lymph Node Dissection for Esophageal Cancer

Mediastinal lymph dissection in esophagectomy for patients with esophageal cancer is important. The dissection of recurrent laryngeal nerve (RLN) lymph nodes could cause RLN injury, vocal cord palsy, pneumonia, and respiratory failure. This retrospective study aimed to evaluate the effects of intraoperative RLN monitoring in esophagectomy and mediastinal lymph node dissection in preventing RLN injury and vocal cord palsy. This study included 75 patients who underwent minimally invasive esophagectomy and mediastinal lymph node dissection for esophageal cancer with (38 patients) and without (37 patients) IONM at Changhua Christian Hospital from 2015 to 2020. The surgical and clinical outcomes were reviewed. Patients in the IONM group had more advanced clinical T status, shorter operation time (570 vs. 633 min, p = 0.007), and less blood loss (100 mL vs. 150 mL, p = 0.019). The IONM group had significantly less postoperative vocal palsy (10.5% vs. 37.8%, p = 0.006) and pneumonia (13.2% vs. 37.8%, p = 0.014) than that in the non-IONM group. IONM was an independent factor for less postoperative vocal cord palsy that was related to postoperative 2-year survival. This study demonstrated that IONM could reduce the incidence of postoperative vocal cord palsy and pneumonia.

Intraoperative nerve monitoring during esophagectomy reduces the risk of recurrent laryngeal nerve palsy

BACKGROUND

Despite the risk of recurrent laryngeal nerve (RLN) palsy during esophagectomy, no established method of monitoring RLN injury is currently available.

METHODS

This study included 187 patients who underwent esophagectomy between 2011 and 2018. Among these, intraoperative nerve monitoring (IONM) was done in 142 patients (IONM group), while the remaining 45 patients underwent conventional surgery without IONM (control group). We investigated the incidence of postoperative complications with regard to the use of IONM.

RESULTS

The overall incidence of postoperative RLN palsy was 28% (52/187). The IONM group showed a significantly lower incidence of postoperative RLN palsy as compared to that in the control group (p = 0.004). The overall incidence of postoperative pneumonia was 22% (41/187) in those with Clavien-Dindo (CD) classification beyond grade 2. There were no significant differences between the incidence of any grade of postoperative pneumonia and the use of IONM (p = 0.195 and 0.333; CD > 2 and > 3, respectively). Multivariate analysis demonstrated that tumors in the upper third [odds ratio (OR) 3.12; 95% confidence interval (CI) 1.04-9.29] and lack of IONM use (OR 2.51; 95% CI 1.17-5.38) were independent factors causing postoperative RLN palsy after esophagectomy.

CONCLUSION

IONM helps to reduce the risk of postoperative RLN palsy after esophageal cancer surgery.

Real-time detection of the recurrent laryngeal nerve in thoracoscopic esophagectomy using artificial intelligence

BACKGROUND

Artificial intelligence (AI) has been largely investigated in the field of surgery, particularly in quality assurance. However, AI-guided navigation during surgery has not yet been put into practice because a sufficient level of performance has not been reached. We aimed to develop deep learning-based AI image processing software to identify the location of the recurrent laryngeal nerve during thoracoscopic esophagectomy and determine whether the incidence of recurrent laryngeal nerve paralysis is reduced using this software.

METHODS

More than 3000 images extracted from 20 thoracoscopic esophagectomy videos and 40 images extracted from 8 thoracoscopic esophagectomy videos were annotated for identification of the recurrent laryngeal nerve. The Dice coefficient was used to assess the detection performance of the model and that of surgeons (specialized esophageal surgeons and certified general gastrointestinal surgeons). The performance was compared using a test set.

RESULTS

The average Dice coefficient of the AI model was 0.58. This was not significantly different from the Dice coefficient of the group of specialized esophageal surgeons (P = 0.26); however, it was significantly higher than that of the group of certified general gastrointestinal surgeons (P = 0.019).

CONCLUSIONS

Our software's performance in identification of the recurrent laryngeal nerve was superior to that of general surgeons and almost reached that of specialized surgeons. Our software provides real-time identification and will be useful for thoracoscopic esophagectomy after further developments.

Application of intraoperative nerve monitoring for recurrent laryngeal nerves in minimally invasive McKeown esophagectomy

BACKGROUND

Mediastinal lymphadenectomy is of great importance during esophagectomy for esophageal squamous cell carcinoma. However, recurrent laryngeal nerve (RLN) injury is a severe complication caused by lymphadenectomy along the RLN. Intraoperative nerve monitoring (IONM) can effectively identify the RLN and reduce the incidence of postoperative vocal cord paralysis (VCP). Here, we describe the feasibility and effectiveness of IONM in minimally invasive McKeown esophagectomy.

METHODS

A total of 150 patients who underwent minimally invasive McKeown esophagectomy from 2016 to 2020 were enrolled in this study. We divided the patients into two groups: a neuromonitoring group (IONM, n = 70) and a control group (control, n = 80). Clinical data, surgical variables, and postoperative complications were retrospectively analyzed and compared.

RESULTS

There was no significant difference in baseline data between the two groups. Postoperative VCP occurred in six cases (8.6%) in the IONM group, which was lower than that in the control group (21.3%, P = 0.032). Postoperative pulmonary complications were found in five cases (7.1%) and 14 in the control group (18.8%, P = 0.037). The postoperative hospital stay in the IONM group was significantly shorter than that in the control group (8 vs. 12, median, P < 0.001). The number of RLN lymph nodes harvested in the IONM group was higher than that in the control group (13.74 ± 5.77 vs. 11.03 ± 5.78, P = 0.005). The sensitivity and specificity of IONM monitoring VCP were 83.8% and 100%, respectively. A total of 66.7% of patients with a reduction in signal showed transient VCP, whereas 100% with a loss of signal showed permanent VCP.

CONCLUSION

IONM is feasible in minimally invasive McKeown esophagectomy. It showed advantages for distinguishing RLN and achieving thorough mediastinal lymphadenectomy with less RLN injury. Abnormal IONM signals can provide an accurate prediction of postoperative VCP incidence.

Efficacy of Intraoperative Recurrent Laryngeal Nerve Monitoring During Thoracoscopic Esophagectomy for Esophageal Cancer: A Systematic Review and Meta-Analysis

Background: Recurrent laryngeal nerve paralysis (RLNP), a severe complication of mini-invasive esophagectomy, usually occurs during lymphadenectomy adjacent to recurrent laryngeal nerve. This systematic review and meta-analysis aimed to evaluate the efficacy of intraoperative nerve monitoring (IONM) in reducing RLNP incidence during mini-invasive esophagectomy. Methods: Systematic literature search of PubMed, EMBASE, EBSCO, Web of Knowledge, and Cochrane Library until June 4, 2021 was performed using the terms "(nerve monitoring) OR neuromonitoring OR neural monitoring OR recurrent laryngeal nerve AND (esophagectomy OR esophageal)." Primary outcome was postoperative RLNP incidence. Secondary outcomes were sensitivity, specificity, and positive and negative predictive values for IONM; complications after esophagectomy; number of dissected lymph nodes; operation time; and length of hospital stay. Results: Among 2,330 studies, five studies comprising 509 patients were eligible for final analysis. The RLNP incidence was significantly lower (odds ratio [OR] 0.33, 95% confidence interval [CI] 0.12-0.88, p < 0.05), the number of dissected mediastinal lymph nodes was significantly higher (mean difference 4.30, 95%CI 2.75-5.85, p < 0.001), and the rate of hoarseness was significantly lower (OR 0.14, 95%CI 0.03-0.63, p = 0.01) in the IONM group than in the non-IONM group. The rates of aspiration (OR 0.31, 95%CI 0.06-1.64, p = 0.17), pneumonia (OR 1.08, 95%CI 0.70-1.67, p = 0.71), and operation time (mean difference 7.68, 95%CI -23.60-38.95, p = 0.63) were not significantly different between the two groups. The mean sensitivity, specificity, and positive and negative predictive values for IONM were 53.2% (0-66.7%), 93.7% (54.8-100%), 71.4% (0-100%), and 87.1% (68.0-96.6%), respectively. Conclusion: IONM was a feasible and effective approach to minimize RLNP, improve lymphadenectomy, and reduce hoarseness after thoracoscopic esophagectomy for esophageal cancer, although IONM did not provide significant benefit in reducing aspiration, pneumonia, operation time, and length of hospital stay.

Outcomes of Esophageal Cancer after Esophagectomy in the Era of Early Injection Laryngoplasty

(1) Background: severe weight loss was reported to be related to unilateral vocal fold paralysis (UVFP) after esophagectomy and could thus impair survival. Concomitant radical lymph node dissection along the recurrent laryngeal nerve during esophageal cancer surgery is controversial, as it might induce UVFP. Early intervention for esophagectomy-related UVFP by administering intracordal injections of temporal agents has recently become popular. This study investigated the survival outcomes of esophagectomy for esophageal squamous cell carcinoma (ESCC) after the introduction of early injection laryngoplasty (EIL). (2) Methods: a retrospective review of patients with ESCC after curative-intent esophagectomy was conducted in a tertiary referral medical center. The necessity of EIL with hyaluronic acid was comprehensively discussed for all symptomatic UVFP patients. The survival outcomes and related risk factors of ESCC were evaluated. (3) Results: among the cohort of 358 consecutive patients who underwent esophagectomy for ESCC, 42 (11.7%) showed postsurgical UVFP. Twenty-nine of them received office-based EIL. After EIL, the glottal gap area, maximum phonation time and voice outcome survey showed significant improvement at one, three and six months measurements. The number of lymph nodes in the resected specimen was higher in those with UVFP than in those without UVFP (30.1 ± 15.7 vs. 24.6 ± 12.7, p = 0.011). The Kaplan-Meier overall survival was significantly better in patients who had UVFP (p = 0.014), received neck anastomosis (p = 0.004), underwent endoscopic resection (p < 0.001) and had early-stage cancer (p < 0.001). Multivariate Cox logistic regression analysis showed two independent predictors of OS, showing that the primary stage and anastomosis type are the two independent predictors of OS. (4) Conclusion: EIL is effective in improving UVFP-related symptoms, thus providing compensatory and palliative measures to ensure the patient's postsurgical quality of life. The emerging use of EIL might encourage cancer surgeons to radically dissect lymph nodes along the recurrent laryngeal nerve, thus changing the survival trend.

The presence of metastatic thoracic duct lymph nodes in Western esophageal cancer patients

BACKGROUND

The thoracic lymphadenectomy during an esophagectomy for esophageal cancer includes resection of the thoracic duct (TD) compartment containing the thoracic duct lymph nodes (TDLN). However, the role of TD compartment resection is still a topic of debate since metastatic TDLNs have only been demonstrated in squamous cell carcinomas in Eastern esophageal cancer patients. Therefore, the aim of this study was to assess the presence and metastatic involvement of TDLNs in a Western population, in which adenocarcinoma is the predominant type of esophageal cancer.

METHODS

From July 2017 to May 2020 all consecutive patients undergoing an open or robot-assisted transthoracic esophagectomy with concurrent lymphadenectomy and resection of the TD compartment in the University Medical Center Utrecht, The Netherlands and the Città della Salute e della Scienza University Hospital in Turin, Italy were included. The TD compartment was resected en bloc and was separated in the operation room by the operating surgeon after which it was macro- and microscopically assessed for (metastatic) TDLNs by the pathologist.

RESULTS

A total of 117 patients with an adenocarcinoma (73%) or squamous cell carcinoma (27%) of the esophagus were included. In 61 (52%) patients TDLNs were found, containing metastasis in 9 (15%) patients. No major complications related to TD compartment resection were observed.

CONCLUSIONS

This is the first study to demonstrate the presence of metastatic TDLNs in adenocarcinomas of the esophagus. This result provides a valid argument to routinely extend the thoracic lymphadenectomy with resection of the TD compartment during an esophagectomy for esophageal cancer.

Efficacy of intraoperative recurrent laryngeal neuromonitoring during surgery for esophageal cancer

AIM

To evaluate the efficacy of intraoperative neuromonitoring in identifying recurrent laryngeal nerves and decreasing the incidence of nerve injury in minimally invasive esophagectomies for esophageal cancers.

METHODS

A total of 167 minimally invasive esophagectomy patients were retrospectively reviewed. They were divided into intraoperative neuromonitoring (n = 84) and no intraoperative neuromonitoring (n = 83) groups, based on whether or not intraoperative neuromonitoring was used during surgery. We compared short-term surgical outcomes and incidence of recurrent laryngeal nerve palsy between the two groups before and after propensity score matching. The association between the loss of signal and recurrent laryngeal nerve palsy was also evaluated.

RESULTS

The incidence of recurrent laryngeal nerve palsy (grade 2 and higher) was lower in the intraoperative neuromonitoring group than in the no intraoperative neuromonitoring group (6.0% vs 21.2%, P = 0.02). The rate of recurrent laryngeal nerve palsy recovery within 6 months was also significantly higher in the intraoperative neuromonitoring group (87.5% vs 20.0%, P < 0.01). The positive and negative predictive values of intraoperative neuromonitoring for recurrent laryngeal nerve palsy were 60% (9/15) and 86.9% (60/69), respectively. The duration from paralysis to recovery was shorter in recurrent laryngeal nerve palsy cases with negative loss of signal results than in cases with positive loss of signal results (median: 43 days vs 95 days).

CONCLUSION

Intraoperative neuromonitoring is useful in identifying recurrent laryngeal nerves and may aid in reducing the incidence of recurrent laryngeal nerve injury during esophageal surgery.

Recurrent laryngeal nerve monitoring during totally robot-assisted Ivor Lewis esophagectomy

Purpose

The robot-assisted approach for Ivor Lewis esophagectomy offers an enlarged, three-dimensional overview of the intraoperative situs. The vagal nerve (VN) can easily be detected, preserved, and intentionally resected below the separation point of the recurrent laryngeal nerve (RLN). However, postoperative vocal cord paresis can result from vagal or RLN injury during radical lymph node dissection, presenting a challenge to the operating surgeon.

Methods

From May to August 2019, 10 cases of robot-assisted minimally invasive esophagectomy (RAMIE) with extended 2-field lymphadenectomy, performed at the University Medical Center Mainz, were included in a prospective cohort study. Bilateral intermittent intraoperative nerve monitoring (IONM) of the RLN and VN was performed, including pre- and postoperative laryngoscopy assessment.

Results

Reliable mean signals of the right VN (2.57 mV/4.50 ms) and the RLN (left 1.24 mV/3.71 ms, right 0.85 mV/3.56 ms) were obtained. IONM facilitated the identification of the exact height of separation of the right RLN from the VN. There were no cases of permanent postoperative vocal paresis. Median lymph node count from the paratracheal stations was 5 lymph nodes.

Conclusion

IONM was feasible during RAMIE. The intraoperative identification of the RLN location contributed to the accuracy of lymph node dissection of the paratracheal lymph node stations. RLN damage and subsequent postoperative vocal cord paresis can potentially be prevented by IONM.

Major Postoperative Complications in Esophageal Cancer After Minimally Invasive Esophagectomy Compared With Open Esophagectomy: An Updated Meta-analysis

BACKGROUND

To evaluate the existing literature comparing cardiopulmonary complications after minimally invasive esophagectomy (MIE) with open esophagectomy (OE) and conduct a meta-analysis based on the relevant studies.

METHODS

A systematic search for articles was performed in Medline, Embase, Wiley Online Library, and the Cochrane Library. The relative risks or odds ratios (ORs) were calculated by using fixed or random-effects models. The I² and X² tests were used to test for statistical heterogeneity. We performed a metaregression for the pulmonary complications with the adenocarcinoma proportion and tumor stage. Publication bias and small-study effects were assessed using Egger's test and Begg's funnel plot.

RESULTS

A total of 30,850 participants were enrolled in the 63 studies evaluated in the meta-analysis. Arrhythmia, pulmonary embolism, pulmonary complications, gastric tip necrosis, anastomotic leakage, and vocal cord palsy were chosen as outcomes. The occurrence rate of arrhythmia was significantly lower in patients receiving MIE than in patients receiving OE (OR = 0.69; 95% CI = 0.53-0.89), with heterogeneity (I² = 30.7%, P = 0.067). The incidence of pulmonary complications was significantly lower in patients receiving MIE (OR = 0.54, 95% CI = 0.45-0.63) but heterogeneity remained (I² = 72.1%, P = 0.000). The risk of gastric tip necrosis (OR = 1.48, 95% CI = 1.07-2.05) after OE was lower than that after MIE. Anastomotic leakage, pulmonary embolism, and vocal cord palsy showed no significant differences between the two groups.

CONCLUSIONS

MIE has advantages over OE, especially in reducing the incidence of arrhythmia and pulmonary complications. Thus, MIE can be recommended as the preferred alternative surgery method for resectable esophageal cancer.

Recent advances in minimally invasive esophagectomy for squamous esophageal cancer

Over the past decade there has been tremendous development in the clinical application of minimally invasive esophagectomy (MIE) for the treatment of squamous esophageal carcinoma. The major challenges in the performance of MIE include limitations in visualization and manipulation within the confined, rigid thoracic cavity; the need for adequate patient positioning and anesthetic techniques to accommodate the surgical exposure; and changes in the surgical steps for achieving radical nodal dissection, especially for the superior mediastinum. The surgical procedure for MIE is more and more standardized, and there is an increasing practice of MIE worldwide. Randomized trials and meta-analyses have confirmed the advantages of MIE over open esophagectomy, including a significantly lower rate of complications and shorter hospital stays. The recent application of robotics technologies for MIE has further enhanced the quality and safety of the surgical dissection, while intraoperative nerve monitoring has contributed to a lower rate of recurrent laryngeal nerve palsy. With the application of new technologies, we expect further improvement in surgical outcomes for MIE in the treatment of squamous esophageal cancer.

Lymph node dissection along the recurrent laryngeal nerves in patients with oesophageal cancer who had undergone chemoradiotherapy: is it safe?

OBJECTIVES

Upper mediastinal lymph node dissection (LND)-especially along the recurrent laryngeal nerve (RN)-is the most challenging part of oesophageal cancer surgery. We investigated whether thoracoscopic RN LND may be safely performed in patients with oesophageal cancer who had undergone chemoradiotherapy (CRT).

METHODS

Patients with oesophageal cancer who had undergone thoracoscopic RN LND (n = 103) were divided into 2 groups according to whether they had prior treatment with CRT or not [the CRT group (n = 65) vs the upfront surgery group (n = 38), respectively]. All patients were operated on by a single surgeon. Intergroup comparisons were made in terms of (i) the number of dissected nodes, (ii) rates of RN palsy and (iii) rates of perioperative complications. The learning curve for the RN LND procedure was investigated using the cumulative sum method.

RESULTS

RN LND after CRT was more technically challenging when performed in the left side. Complete skeletonization of the left RN was achieved only in 66.2% of patients in the CRT group (vs 86.8% in the upfront surgery group; P = 0.022). The rate of postoperative left side RN palsy was significantly higher in the CRT group (26.6%) than in the upfront surgery group (7.9%, P = 0.022), albeit resulting in neither higher pneumonia rates nor longer hospital stays. The cumulative sum analysis revealed a steep learning curve for left RN LND in the CRT group. Unfortunately, an acceptable proficiency (left RN palsy rate: 15%) was not achievable even after treatment in 65 cases.

CONCLUSIONS

Thoracoscopic RN LND is safe but poses significant challenges in CRT-treated patients.

Prevalence and resource utilization for vocal fold paralysis/paresis after esophagectomy

OBJECTIVES/HYPOTHESIS

Vocal fold paralysis/paresis (VFP) is an uncommon but serious complication following esophagectomy. The objectives of this study were to: 1) identify the prevalence of VFP and associated complications after esophagectomy in the United States, and 2) determine the utilization and otolaryngology-head and neck surgery/speech-language pathology (OHNS/SLP) and predictors of such utilization in the management of these patients.

STUDY DESIGN

Retrospective database analysis.

METHODS

The National Inpatient Sample (NIS) represents a 20% stratified sample of discharges from US hospitals. Using International Classification of Diseases, Ninth Revision, Clinical Modification codes, patients undergoing esophagectomy between 2008 and 2013 were identified in the NIS. Subcohorts of patients with VFP and OHNS/SLP utilization were also identified. Weighted logistic regression models were used to compare binary outcomes such as complications; generalized linear models were used to compare total hospital charges and length of stay (LOS).

RESULTS

We studied 10,896 discharges, representing a weighted estimate of 52,610 patients undergoing esophagectomy. The incidence of VFP after esophagectomy was 1.96%. Compared to those without VFP, patients with VFP had a higher incidence of postoperative pneumonia, more medical complications, and were more likely to undergo tracheostomy; hospital charges and LOS were also higher. Of the patients with VFP, 35.0% received OHNS/SLP intervention.

CONCLUSIONS

VFP after esophagectomy is associated with postoperative complications, prolonged LOS, and higher hospital costs. OHNS/SLP intervention occurred in roughly one-third of postesophagectomy VFP patients, suggesting there may be opportunities for enhanced evaluation and management of these patients.

LEVEL OF EVIDENCE

4 Laryngoscope, 128:2815-2822, 2018.

Technique and surgical outcomes of mesenterization and intra-operative neural monitoring to reduce recurrent laryngeal nerve paralysis after thoracoscopic esophagectomy: A cohort study

BACKGROUND

Because the thoracic esophageal carcinoma has a high metastatic rate to the upper mediastinal lymph nodes, especially along the recurrent laryngeal nerves (RLN), it is crucial to perform a complete lymphadenectomy along the RLN without complications. Although intraoperative neural monitoring (IONM) during thyroid surgery has gained widespread acceptance as a useful tool for visual nerve identification, utilization of IONM during esophageal surgery has not become common. Here, we describe our procedures, focusing on a lymphadenectomy along the RLN utilizing the IONM.

METHODS

Eighty-seven patients who underwent prone esophagectomy between December 2009 and September 2017 were included in this study. We divided patients into two groups: neural monitoring group (Nm, n = 31) and conventional method group without IONM (Cm, n = 56). We first dissect around the esophagus, preserving the membranous structure; mesoesophagus, which contains tracheoesophageal artery; RLN; and lymph nodes (mesenterization). In Nm group, we next identify the location of the RLN, which runs in the mesoesophagus using IONM before visual contact. Next, we perform lymphadenectomy around the RLN, preserving the nerve itself. Early surgical outcomes were retrospectively compared between two groups.

RESULTS

In all 31 cases in the Nm group, we detected the location of the RLN before the visual contact. The sensitivity and specificity of the IONM to detect the RLN paralysis were 67% and 96%, respectively. Postoperative RLN paralysis was observed in 3 cases in the Nm group (9.7%), which was lower than that in the Cm group (32.1%, p = 0.03). Clavien-Dindo grade 2 and over aspiration were seen in 2 (Nm, 6.5%) and 16 (Cm, 28.6%) cases (p = 0.01), respectively. The postoperative hospital stay was shorter in the Nm group (22 days, median) than in the Cm group (39 days, median, p = 0.0002). The number of dissected mediastinal lymph nodes was similar in both groups (25 vs. 20, median, p = 0.12).

CONCLUSIONS

The combination of IONM and the concept of the mesoesophagus have substantial advantages in allowing accurate and safe mediastinal lymphadenectomy during prone esophagectomy.

Recurrent laryngeal nerve injury after esophagectomy for esophageal cancer: incidence, management, and impact on short- and long-term outcomes

BACKGROUND

Recurrent laryngeal nerve (RLN) injury caused by esophagectomy may lead to postoperative morbidity, however data on long-term recovery are scarce. The aim of this study was to evaluate the consequences of RLN palsy (RLNP) in terms of pulmonary morbidity and long-term functional recovery.

METHODS

Patients who underwent a 3-stage transthoracic (McKeown) or a transhiatal esophagectomy for esophageal carcinoma in the University Medical Center Utrecht (UMCU) between January 2004 and March 2016 were included from a prospective database. Multivariable analyses were conducted to assess the association between RLNP and pulmonary complications and hospital stay. Data regarding long-term recovery were summarized using descriptive statistics.

RESULTS

Out of the 451 included patients, 47 (10%) were diagnosed with RLNP. Of the patients with RLNP, 34 (7%) had a unilateral lesion, 8 (2%) had a bilateral lesion, and in 5 (1%) the location of the lesion was unknown. The incidence of RLNP was 3/127 (2%) in the transhiatal group, and 44/324 (14%) in the McKeown group. RLNP after McKeown esophagectomy was associated with a higher incidence of pulmonary complications (OR 2.391; 95% CI 1.222-4.679; P=0.011), as well as a longer hospital stay (+4 days) (P=0.001). Of the RLNP patients with more than 6 months follow up almost half recovered fully {median follow-up of 17.5 [7-135] months}. Of the remainder, six required a surgical intervention and the others had residual symptoms.

CONCLUSIONS

RLNP after McKeown esophagectomy is associated with an increased pulmonary complication rate, longer hospital stay, and a moderate long-term recovery. Further studies are necessary that examine technologies, which may reduce RLNP incidence and contribute to the early detection and treatment of RLNP.

Continuous intraoperative vagus nerve stimulation for monitoring of recurrent laryngeal nerve during minimally invasive esophagectomy

For squamous cell carcinoma of the esophagus, extended mediastinal lymphadenectomy especially around the bilateral recurrent laryngeal nerves (RLN) is associated with high risk of nerve injury. This does not only result in hoarseness of voice, increase the chance of pulmonary complications, but would also affect the quality of life of patients in the long term. Methods to improve safety of lymphadenectomy are desirable. Continuous intraoperative nerve monitoring (CIONM) based on a system using vagus nerve stimulation was tested. In thyroidectomy, this system has been shown to be useful. Our patient cohort was unselected, with the intent to perform bilateral RLN dissection undergoing video-assisted thoracoscopic (VATS) esophagectomy. Intermittent nerve stimulation for mapping and CIONM were employed to monitor left RLN nodal dissection, while only intermittent stimulation was used for the right RLN. CIONM has the potential to aid RLN dissection. The learning curves for the placement technique of CIONM, the threshold level and the interpretation of myographic amplitude and latency have been overcome. With the availability of nerve mapping and CIONM, more aggressive and thorough nodal dissection may be possible with less fear of RLN injury.

Continuous Intraoperative Neuromonitoring Study Using Pigs for the Prevention of Mechanical Recurrent Laryngeal Nerve Injury in Esophageal Surgery

PURPOSES

During esophageal surgery, clamping injury and injury associated with the use of energy devices are common mechanisms underlying intraoperative recurrent laryngeal nerve (RLN) damage. Recently, intraoperative neuromonitoring (IONM) has been applied to prevent RLN injury. This study was aimed at investigating the changes in the EMG signals associated with clamping injury of the RLN caused by picking up of the nerve with tweezers in domestic pigs.

METHODS

Six domestic pigs (12 RLNs) underwent continuous IONM (CIONM) by our original automated periodic vagal nerve stimulation method.

RESULTS

Our system can be used safely and accurately. The signals showed a decrease of the amplitude when the RLN was picked up and closed slowly by the double-action Maryland with jaw covers. If the clamp was released before the signal amplitude decreased to 50% of the baseline, the signal showed gradual recovery to the baseline in 12 ± 3 minutes.

CONCLUSION

Although there were limitations in our study using domestic pig, including the small sample size, our results are expected to contribute to a decrease in the incidence of RLN damage during esophageal surgery.

Impact of routine recurrent laryngeal nerve monitoring in prone esophagectomy with mediastinal lymph node dissection

BACKGROUND

The problem of recurrent laryngeal nerve (RLN) paralysis (RLNP) after radical esophagectomy remains unresolved. Several studies have confirmed that intraoperative nerve monitoring (IONM) of the RLN during thyroid surgery substantially decreases the incidence of RLN damage. This study tried to determine the feasibility and effectiveness of IONM of the RLN during thoracoscopic esophagectomy in the prone position for esophageal cancer.

METHODS

All 108 patients who underwent prone esophagectomy at Tohoku University Hospital between July 2012 and March 2015 were included in this study. We divided patients into two groups: a control group (No-Monitoring group, surgery without IONM; n = 54) and a study group (Monitoring group, surgery with IONM; n = 54). In Monitoring group, neural stimulation was performed for both RLNs before and after dissection in the thoracic procedure, then for RLNs and vagus nerves (VNs) in the cervical procedure. The feasibility of IONM in Monitoring group and early surgical outcomes were retrospectively compared with those in No-Monitoring group.

RESULTS

IONM could be performed for 47 cases (87.0%) in Monitoring group. Reasons for discontinuation were use of muscle relaxants (3 patients), change in thoracotomy procedure (2 patients), past rib bone fracture (1 patient), and allergic shock by transfusion (1 patient). Right RLNPs were identified postoperatively in 4 patients, and left RLNPs in 23 patients. IONM sensitivities were 92.7 and 88.0% for the right and left VNs, respectively. Incidences of postoperative RLNP, aspiration, and primary pneumonia did not differ significantly between groups.

CONCLUSIONS

This study confirmed the feasibility and safety of IONM of the RLN for thoracoscopic esophagectomy in the prone position. No significant differences in postoperative outcomes were seen between esophagectomy with and without IONM.

Recurrent Laryngeal Nerve Paralysis after Esophagectomy: Respiratory Complications and Role of Nerve Reconstruction

Recurrent laryngeal nerve paralysis (RLNP) after esophagectomy is a common complication and associated with aspiration pneumonia. In this study, we assessed the risk of RLNP and the usefulness of immediate reconstruction of recurrent laryngeal nerve (RLN) to prevent respiratory complications after esophagectomy. Seven hundred and eighty-two consecutive patients underwent an esophagectomy with three-field lymph node dissection, simultaneous gastric conduit reconstruction, and cervical anastomosis. Vocal cord function was observed using a flexible laryngoscope. Reconstruction between RLN and ipsilateral vagus nerve was performed during esophagectomy. RLNP was observed in 229 (29.3%) of the patients after esophagectomy: 198 unilateral and 31 bilateral cases. Of the 198 unilateral RLNP, vocal cord paralysis was observed predominantly on the left side (82.7%). RLNP was significantly associated with postoperative respiratory complications (P < 0.001) requiring a tracheotomy (P < 0.001) and mechanical ventilation (P < 0.001) and was also associated with esophagogastric anastomotic leakage (P = 0.015); consequently, the postoperative hospital stay was longer for patients with RLNP (P < 0.001). A longer operation time (P < 0.001) and advanced age (P = 0.038) were identified as significant independent predictors of RLNP. Resection of the RLN together with metastatic nodes was performed in 29 cases. The patients underwent RLN reconstruction (n = 11) had a significantly shorter postoperative hospital stay than those without RLN reconstruction (n = 18) (P = 0.019). In conclusion, RLNP was related to a poorer postoperative course among patients undergoing an esophagectomy. New surgical technologies are recommended for prevention of RLNP.

Intraoperative neurophysiologic monitoring: basic principles and recent update

The recent developments of new devices and advances in anesthesiology have greatly improved the utility and accuracy of intraoperative neurophysiological monitoring (IOM). Herein, we review the basic principles of the electrophysiological methods employed under IOM in the operating room. These include motor evoked potentials, somatosensory evoked potentials, electroencephalography, electromyography, brainstem auditory evoked potentials, and visual evoked potentials. Most of these techniques have certain limitations and their utility is still being debated. In this review, we also discuss the optimal stimulation/recording method for each of these modalities during individual surgeries as well as the diverse criteria for alarm signs.