Critical swallowing functions contributing to dysphagia in patients with recurrent laryngeal nerve paralysis after esophagectomy

BACKGROUND

Recurrent laryngeal nerve paralysis (RLNP) after esophagectomy can cause aspiration because of incomplete glottis closure, leading to pneumonia. However, patients with RLNP often have preserved swallowing function. This study investigated factors that determine swallowing function in patients with RLNP.

METHODS

Patients with esophageal cancer who underwent esophagectomy and cervical esophagogastric anastomosis were enrolled between 2017 and 2020. Videofluoroscopic examination of swallowing study (VFSS) and acoustic voice analysis were performed on patients with suspected dysphagia including RLNP. Dysphagia in VFSS was defined as score ≥ 3 of the 8-point penetration-aspiration scale VFSS and acoustic analysis results related to dysphagia were compared between patients with and without RLNP.

RESULTS

Among 312 patients who underwent esophagectomy, 74 developed RLNP. The incidence of late-onset pneumonia was significantly higher in the RLNP group than in the non-RLNP (18.9 vs. 8.0%, P = .008). Detailed swallowing function was assessed by VFSS in 84 patients, and patients with RLNP and dysphagia showed significantly shorter maximum diagonal hyoid bone elevation (10.62 vs. 16.75 mm; P = .003), which was a specific finding not seen in patients without RLNP. For acoustic voice analysis, the degree of hoarseness was not closely related to dysphagia. The length of oral intake rehabilitation for patients with and without RLNP was comparable if they did not present with dysphagia (8.5 vs. 9.0 days).

CONCLUSIONS

Impaired hyoid bone elevation is a specific dysphagia factor in patients with RLNP, suggesting compensatory epiglottis inversion by hyoid bone elevation is important for incomplete glottis closure caused by RLNP.

[The value and related complications of lymph node dissection along bilateral recurrent laryngeal nerves in esophageal cancer patients]

Esophageal cancer is one of the most common malignant tumors of digestive tract, lymph node metastasis is a frequently encountered metastasis in the esophageal cancer patients. The number of lymph node metastasis is reported as an important prognostic factor, and it also affects the choice of postoperative treatments in the esophageal cancer. It was reported that the recurrent laryngeal nerve lymph nodes are the most common sites of nodal metastasis and need to be completely dissected during the esophagectomy for thoracic esophageal cancers. Dissection of the lymph nodes along bilateral recurrent laryngeal nerves not only improves the accuracy of staging, but also improves postoperative survival of esophageal cancer patients due to reducing the local recurrence. However, it also brings problems such as injury of laryngeal recurrent nerves, and increases postoperative complications such as pulmonary complications and malnutrition due to aspiration and coughing. Therefore, it is necessary to preserve the structure and function of bilateral recurrent laryngeal nerves during esophagectomy through careful manipulations, and minimize the impact of complications in prognosis and quality of life from injury to the recurrent laryngeal nerve.

Diagnosis of recurrent laryngeal nerve paralysis following esophagectomy by evaluating movement of the vocal cords and arytenoid cartilages using ultrasonography

Advancements in thoracoscopic surgery have provided us with a deeper anatomical understanding of recurrent laryngeal nerve paralysis (RLNP), which is likely to occur after lymph node dissection. Taking a novel approach to researching the diagnosis of RLNP, we evaluated movement of the vocal cords and arytenoid cartilages using ultrasonography in patients who underwent thoracoscopic esophagectomy. RLNP occurred in six of the 24 patient cohort. The rate of hoarseness and difficulty in discharging sputum was significantly higher in the paralyzed group than in the non-paralyzed group. The diagnostic accuracy of RLNP by ultrasonography had a sensitivity of 83.3% (5/6), a specificity of 88.8% (16/18), a false positive rate of 5.6% (1/18), and a false negative rate of 0% (0/6). Although it is not completely accurate, our findings indicate that ultrasonography is quite effective for diagnosing RLNP, more so in combination with clinical symptoms. Ultrasonography may also be effective for identifying patients who are amenable to laryngoscopy for diagnosing RLNP, or for evaluating the recovery status of nerve paralysis.

Two cases of left recurrent laryngeal nerve paralysis after right superior mediastinal node dissection

Background

Ipsilateral recurrent laryngeal nerve paralysis is one of the rare complications during the superior mediastinal node dissection for lung cancer. However, very few reports of contralateral recurrent laryngeal nerve paralysis during the procedure are available.

Case presentation

Two women aged 74 and 80 years developed hoarseness after undergoing right upper lobectomy and right superior mediastinal node dissection for primary lung cancer. Postoperative laryngoscopy in the two patients confirmed left vocal cord paralysis.

Conclusion

Node dissection is performed in the standard procedure for right upper lobe lung cancer. At this time, care must be taken not to cause damage not only to the recurrent laryngeal nerve on the ipsilateral side but also to the recurrent laryngeal nerve on the contralateral side.

Preoperative computed tomography predicts the risk of recurrent laryngeal nerve paralysis in patients with esophageal cancer undergoing thoracoscopic esophagectomy in the prone position

BACKGROUND

Recurrent laryngeal nerve paralysis (RLNP) after thoracoscopic esophagectomy for esophageal cancer (EC) is known to be a major complication leading to poor quality of life. RLNP is mainly associated with surgical procedures performed near the RLN. Therefore, with focus on the region of the RLN, we used preoperative computed tomography to investigate the risk factors of RLNP in patients with EC undergoing thoracoscopic esophagectomy.

METHODS

We retrospectively examined 77 EC patients who underwent thoracoscopic esophagectomy in the prone position at our department between January 2010 and December 2018. Bilateral cross-sectional areas (mm²) of the fatty tissue around the RLN at the level of the lower pole of the thyroid gland were measured on preoperative axial computed tomography (CT) images. Univariate and multivariate logistic regression analysis was used to evaluate the association between the incidence of RLNP and patient clinical factors, including the cross-sectional areas.

RESULTS

RLNP occurred in 24 of 77 patients (31.2%). The incidence of RLNP was significantly more frequent on the left side than on the right. (26% vs. 5.2%, respectively). Univariate analysis identified the following left RLNP risk factors: intrathoracic operative time (> 235 min), and area around the RLN (> 174.3 mm²). Multivariate analysis found that the area around the RLN was an independent risk factor of left RLNP.

CONCLUSION

An increased area around the RLN measured on an axial CT view at the level of the lower pole of the thyroid gland was a risk factor of RLNP in EC patients undergoing thoracoscopic esophagectomy in the prone position.

Minimally invasive esophagectomy and radical lymph node dissection without recurrent laryngeal nerve paralysis

Background

We introduce a novel operative technique to dissect lymph nodes adjacent to the recurrent laryngeal nerve, referred to as the “native tissue preservation” technique. Using this technique, there was no damage to the recurrent laryngeal nerve, which is maintained in its anatomical position.

Methods

From September 2016 to December 2018, minimally invasive esophagectomy was performed in the left lateral decubitus position in 87 patients with esophageal cancer. The native tissue preservation technique for lymphadenectomy around the recurrent laryngeal nerve was used, and all patients were evaluated for recurrent laryngeal nerve paralysis.

Results

Minimally invasive esophagectomy was completed in all patients without conversion to thoracotomy. Although an extended lymphadenectomy was performed in all patients, there were no grade II or higher complications (Clavien–Dindo classification) and no incidence of recurrent laryngeal nerve paralysis.

Conclusion

The native tissue preservation technique may reduce the incidence of recurrent laryngeal nerve paralysis after minimally invasive esophagectomy with radical lymph node dissection.

Electronic supplementary material

The online version of this article (10.1007/s00464-020-07372-3) contains supplementary material, which is available to authorized users.

An Investigation of Factors Related to Food Intake Ability and Swallowing Difficulty After Surgery for Thoracic Esophageal Cancer

Swallowing difficulty is among the major complications that can occur after surgery for thoracic esophageal cancer. Recurrent laryngeal nerve paralysis (RLNP) has been considered the most significant cause of a postoperative swallowing difficulty, but association between the two has not been adequately explained. We investigated the relation between postoperative RLNP and swallowing difficulty by means of video fluoroscopy. Our study included 32 patients who underwent subtotal esophagectomy for thoracic esophageal cancer at St. Marianna University School of Medicine between April 2014 and March 2017. We evaluated patients’ age and sex, disease stage, preoperative presence of a swallowing difficulty, nutritional status, extent and duration of surgery, blood loss volume, and postoperative presence of RLNP and/or hoarseness. Patients were divided into two groups according to whether oral food intake was possible when video fluoroscopy was performed on postoperative day (POD) 7, and we analyzed the associated factors. Postoperative RLNP occurred in 21 patients (65.6%); hoarseness occurred in 19 (59.4%). Eleven patients (34.4%) suffered swallowing difficulty that prevented food intake. No significant association was found between postoperative swallowing difficulty and postoperative RLNP or hoarseness, but a significant relation was found between the prognostic nutritional index and intraoperative lymph node dissection. Multivariable analysis revealed a significant relation between postoperative swallowing difficulty and only one factor: cervical lymph node dissection (P = 0.0075). There appears to be no relation between RLNP pursuant to esophageal cancer surgery and swallowing difficulty that prevents oral food intake.

Lateral thermal spread induced by energy devices: a porcine model to evaluate the influence on the recurrent laryngeal nerve

BACKGROUND

Recurrent laryngeal nerve (RLN) paralysis is a frequently observed complication after esophagectomy, and thermal injury is considered to be one of the causes. The difference in the lateral thermal spread associated with the grasping range of various energy devices remains unknown.

METHODS

Ultrasonic devices (Harmonic® HD1000i and Sonicision™) and a vessel-sealing device (Ligasure™) were studied. We evaluated the temperature of these devices, the activation time required, and the thermal spread on porcine muscle when the devices were used with different grasping ranges (thermal spread study). In addition, we evaluated the influence of thermal spread by short grasping use of the energy devices on the viability of RLN in a live porcine model (NIM study).

RESULTS

In the thermal spread study, the temperature of the ultrasonic devices lowered as grasping range increased, whereas the highest temperature of Ligasure was observed when used with two-thirds grasping. The activation time of ultrasonic devices became longer as grasping range increased, whereas the grasping range did not influence the activation time of Ligasure. Thermal spreads 1 mm from the energy devices were unaffected by the grasping ranges. Although the temperature of the Ligasure was lower than that of the ultrasonic devices, thermal spread by Ligasure was significantly greater than that induced by the ultrasonic devices. In the NIM study, the activation of the Sonicision with one-third grasping range did not cause EMG changes at distances of up to 1 mm from the RLN, whereas applying Ligasure with a one-third grasping range 1 mm away from the RLN led to a critical result.

CONCLUSIONS

The grasping range did not influence the thermal spread induced by the energy devices. Ultrasonic devices may be safer in terms of lateral thermal spread to the RLN than Ligasure.

Lateral thermal spread and recurrent laryngeal nerve paralysis after minimally invasive esophagectomy in bipolar vessel sealing and ultrasonic energy devices: a comparative study

BACKGROUND

This study aimed to compare the extent of lateral thermal spread of surrounding tissues after the use of advanced bipolar and ultrasonic coagulation and shearing devices. Association between recurrent laryngeal nerve paralysis (RLNP) and such devices was assessed in patients who underwent minimally invasive esophagectomy (MIE).

METHODS

LigaSure^™ (LS) and Sonicision^™ (SONIC) were used. In ex vivo experiments using the porcine muscle, blade temperature and tissue temperature were measured using a thermometer after the activation of both devices. For the clinical assessment, 46 consecutive patients who received MIE were retrospectively assessed.

RESULTS

The temperature generated at the blade of both devices increased with the activation time. The blade temperature of LS was significantly lower than that of SONIC (P < 0.001). The blade temperature of SONIC exceeded 100 °C after 3-s activation. The temperature of surrounding tissues after a single activation of the devices decreased with the tissue distance from activation blade. The temperatures of tissues at 1 and 2 mm away from the blade side of LS were significantly lower than those of SONIC (P = 0.001 and P < 0.001, respectively). The temperature of tissue 2 mm away from the blade side of LS increased 6.4 °C from the baseline temperature. Furthermore, the incidence of RLNP in the LS group was lower than that in the SONIC group (P = 0.044).

CONCLUSION

This study highlights the necessity of spatial and temporal recognition of the thermal spread of coagulation and shearing devices to reduce the thermal injuries following MIE.

Ortner syndrome secondary to aortic aneurysm

Ortner syndrome refers to vocal cord paralysis resulting from compression of the left recurrent laryngeal nerve by abnormal mediastinal vascular structures. We report a case of Ortner syndrome in a 75-year-old male secondary to aortic arch aneurysm.

Comparison of vocal outcome following two different procedures for immediate RLN reconstruction

The objective of this study was to compare time-dependent improvements in phonatory function and stroboscopic findings following two different procedures for immediate reconstruction of the recurrent laryngeal nerve (RLN) during neck tumor extirpation. Seventeen patients with neck tumors, consisting of advanced thyroid cancer (n = 15), metastatic neck lymph nodes from other malignant lesions (n = 2), underwent resection of the primary lesion and involved RLN. Immediate RLN reconstruction by either: (1) ansa cervicalis nerve (ACN) to RLN anastomosis (n = 8); or (2) placement of the great auricular nerve (GAN) between the cut ends of the RLN (n = 9) was performed from 2000 to 2011. Phonatory function [maximum phonation time, mean airflow rate (MFR), jitter, and shimmer) and stroboscopic findings (regularity, amplitude, and glottal gap) were examined at 1, 6, and 12 months postoperatively. Stroboscopic findings were assessed by two otolaryngologists and one speech pathologist. There were no significant differences in any parameter for either phonatory function or stroboscopic findings between ACN and GAN with the exception of jitter and shimmer, in which ACN was superior to GAN at 1 month postoperatively. All parameters improved significantly between 1 and 12 months postoperatively for both phonatory function and stroboscopic findings (P < 0.05). Either method of immediate RLN reconstruction at the time of neck tumor extirpation (i.e., ACN or GAN) provided both excellent long-term postoperative phonatory function and stroboscopic findings, and there was little difference in vocal outcome between the two procedures.

Improving the functionality of intra-operative nerve monitoring during thyroid surgery: is lidocaine an option?

Intra-operative nerve monitoring (IONM) is rapidly becoming a standard of care in many institutions across the country. In the absence of neuromuscular blocking agents to facilitate the IONM, the depth of anesthesia required to abolish the laryngo tracheal reflexes often results in profound hemodynamic instability during surgery, necessitating the use of large doses of sympathomimetic amines. The excessive alpha and beta adrenergic effects exhibited by these agents are undesirable in the presence of cardiovascular co-morbidities. Trying to strike a balance frequently results in an unsatisfactory intra-operative course. In the course of the near total thyroidectomy performed on a 60-year-old female, we employed lidocaine infusion at 1.5 mg/kg/hour following a bolus dose of 1 mg/kg. The troublesome laryngo tracheal reflexes were successfully blunted and we were able to moderate the depth of anesthesia resulting in stable hemodynamics. A bispectral index monitor was employed to guard against “recall” and a train of four monitor was used to ensure the absence of inadvertent neuromuscular blockade. During the surgery, there was loss of signal on the left recurrent laryngeal nerve (RLN). The signal strength was restored by rotating the endotracheal tube on its long axis to realign the electrode with the vocal cords under Glidescope^® visualization.