Management of patients with bilateral recurrent laryngeal nerve paralysis following esophagectomy.

BACKGROUND: Recurrent laryngeal nerve paralysis (RLNP) is a common complication after esophagectomy which can cause severe pulmonary complications. However, bilateral RLNP has been rarely reported in esophagectomy patients. The objective of our study is to investigate the clinical significance of patients who had bilateral RLNP following esophagectomy. METHODS: We retrospectively reviewed patients who underwent esophagectomy at a single center from 1994 to 2018. Among these, patients with bilateral vocal cord paralysis were included in this study. RESULTS: A total of 3217 patients were reviewed and 400 (12.4%) patients had RLNP, including 56 patients with bilateral RLNP identified by laryngoscopic examination. During the postoperative managements, 10 of the 56 patients (17.9%) required tracheostomy. Among them, two died of acute respiratory distress syndrome and the other eight patients were discharged after removing the tracheostomy tube. The median lengths of hospital and intensive care unit stay were 19.5 (range 8-157) and 2 (range 1-46) days, respectively. Forty-six patients (83.6%) were discharged with oral feeding after swallowing therapy including tongue holding maneuver and head tilt exercise. The other five patients (8.9%) were discharged with alternative enteral feeding via jejunostomy, but they were able to achieve oral diet 2-3 months after surgery. CONCLUSION: Bilateral RLNP following esophagectomy was rare, but it required great attention to prevent severe respiratory complications. However, only a few patients required tracheostomy and the majority achieved oral ingestion after intensive rehabilitation. Feeding education and respiratory rehabilitation are critical during the management of patients with bilateral RLNP.

MRI Study of Jellyfish Collagen, Hyaluronic Acid, and Cadaveric Dermis for Injection Laryngoplasty.

OBJECTIVES/HYPOTHESIS: Test a new jellyfish collagen biomaterial aimed to increase duration of injection medialization laryngoplasty (IL) against two products in clinical practice. STUDY DESIGN: Animal model. METHODS: Left recurrent laryngeal nerve sectioning and IL were performed in New Zealand White rabbits (N = 6/group). Group 1 received micronized cross-linked jellyfish collagen (MX-JC) and adipose derived stem cells (ADSCs), Group 2, MX-JC alone, Group 3, cross-linked hyaluronic acid (X-HA), and Group 4, micronized acellular dermis (MACD). Animals were sacrificed at 4 and 12 weeks. Major outcomes were MRI tissue volumes and histopathology. RESULTS: After 100 µL IL MRI volumes (means ± STD) at 4 and 12 weeks were: Group 1: 27.2 ± 15.6 and 13.1 ± 5.2 µL, Group 2: 60.8 ± 18 and 27.8 ± 2.47 µL, Group 3: 27.4 ± 12 and 10.6 ± 8 µL, and Group 4: 37.5 ± 11 and 9.85 ± 1 µL. Group 2 volumes were largest and Group 3 were smallest in all comparisons (P < .05). Histologically, low grade inflammatory responses were observed in Group 1, mild histiocytic infiltration in Group 2, widespread muscle fiber loss in Group 3, and plasmocytic infiltration in Group 4. CONCLUSIONS: MX-JC showed the least resorption at 4 and 12 weeks among all groups. T cell inflammatory responses were observed with MX-JC but were reduced by 12 weeks while B cell immune responses, indicative of antibody priming, were predominantly noted with MACD. MX-JC + ADSC showed low grade immunity while the XHA showed greater myocyte loss compared to the other groups. LEVEL OF EVIDENCE: NA Laryngoscope, 131:E2452-E2460, 2021.

Morphometric Differences in the Recurrent Laryngeal Nerve in Patients with Vocal Fold Paralysis.

OBJECTIVES: Injury to the recurrent laryngeal nerve (RLN), if severe enough, can result in vocal fold paralysis. Reinnervation surgery can improve patient outcomes, but previous studies have reported a negative correlation between time since onset of paralysis and surgical outcomes. The ability of the paralyzed nerve to serve as a conduit for donor nerve fibers may be a factor in the success of reinnervation; however, changes in RLN composition after paralysis have not been well studied. Therefore, we investigated the morphometric composition of explanted RLN sections from patients who had experienced vocal fold paralysis for varying length of times. METHODS: Nine nerve sections from unilateral vocal fold paralysis (UVP) patients and seven control nerve sections were analyzed for morphometric parameters including fascicular area, fiber count, fiber density, fiber packing, mean g-ratio, and fiber diameter distribution. Nerves from UVP patients were also compared as a function of time since UVP onset. RESULTS: In comparison to control nerves, paralyzed nerves were found to have significantly lower fiber densities and fiber packing, higher mean g-ratio values, and a shift in diameter distributions toward smaller diameter fibers. With respect to paralysis duration, no significant differences were observed except in fiber diameter distributions, where those with paralysis for >2 years had distributions that were significantly shifted toward smaller diameter fibers. CONCLUSIONS: The morphometric data presented here suggest that correlations between the time since onset of vocal fold paralysis and reinnervation outcomes may be due to fiber size changes in the paralyzed nerve over time.

Comparative study of three types of lymphadenectomy along the left recurrent laryngeal nerve by minimally invasive esophagectomy.

BACKGROUND: The objective of this study was to compare three kinds of lymphadenectomy methods along the recurrent laryngeal nerve (RLN) and assess the safety and effectiveness of the new method. METHODS: A total of 194 patients with esophageal cancer who underwent minimally invasive esophagectomy (MIE) at our institution from May 2013 to May 2017 were analyzed retrospectively. According to the method of lymphadenectomy along the left RLN, the patients were divided into three groups: 75 cases underwent the conventional method (A group), 80 cases the skeletonized method (B group) and 39 cases the modified Bascule method (C group). The number of dissected lymph nodes and surgical outcomes were recorded and compared to identify differences among the three groups. RESULTS: The frequency of metastasis to the LRLN lymph node was 18.6% among all patients, and 12%, 20% and 28% in groups A, B and C, respectively. The number of harvested lymph nodes (total/chest/LRLN/LRLN+) in group B and group C were significantly greater than that of group A, but not significant between group B and group C. The hoarseness rate in group C was 15.4%, which was lower than the rate in group B (21.3%) and higher than the rate in group A (13.3%), but there was no statistical significance. CONCLUSIONS: The new method for lymphadenectomy along the left RLN during MIE in the semi-prone position is safe and reliable. It provides sufficient lymph node dissection along the left RLN.

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.

Laryngeal nerve morbidity in 1.273 central node dissections for thyroid cancer.

AIM: We assess the prevalence and mechanism of recurrent laryngeal nerve (RLN) injury in central neck dissection (CND) for thyroid cancer. METHODS: CND with intraoperative neural monitoring was outlined in 1.273 nerves at risk (NAR). RLN lesions were stratified according to: timing (during thyroidectomy versus CND), segmental vs. diffuse injury, mechanism, severity, location, number of lymph nodes dissected and metastastatic. EMG parameters were recorded. RESULTS: 49/1.273NAR (3,8%) documented RLN palsy. 25 nerves were injured during thyroidectomy, 8 while CND. In 16 no precise moment or mechanism of injury was identified. A disrupted point could be identified in 19/25 (76%) and 7/8 (87%) respectively for thyroidectomy and CND steps. Diffuse injury, occurred in 24% and 12,5% respectively for thyroidectomy and CND. Nerves were injured in the all cervical nerve course without any major location for incidence for CND; for thyroidectomy most nerves were injured in the last 1 cm course. Traction (36%) was the leading cause of RLN injury for thyroidectomy. For solely CND, traction, entrapment and thermal injuries were equally frequent. Permanent vs. transient injuries were respectively 8% (4/49) and 92% (n.45/49), overall. Permanent lesions were equally distributed. CONCLUSIONS: During CND, RLN palsy still occurs with routine exposure of the nerve even combined with IONM. The incidence of nerve lesions during thyroidectomy is higher than that of CND.

Safety assessment of the use of ultrasonic energy in the proximity of the recurrent laryngeal nerve in a porcine model.

BACKGROUND: Advanced bipolar and ultrasonic energy have demonstrated reduction of operating time and blood loss in thyroidectomy. However, these devices generate heat and thermal dispersion that may damage adjacent structures such as the recurrent laryngeal nerve (RLN). This study was designed to evaluate the safety profile of the Harmonic Focus+® (HF+) device through the evaluation of thermal injury to the RLN using different algorithms of distance and time with state of the art technology. METHODS: 25 Vietnamese pigs underwent activation of HF+ in the proximity of their RLN. They were divided into 4 groups according to activation distance (3 mm, 2 mm, 1 mm and on the RLN). Time of activation, time between tones of the ultrasonic generator, changes in the electromyographic signal using continuous nerve neuromonitoring, vocal fold mobility assessed by direct laryngoscopy and histological thermal damaged were evaluated. RESULTS: None of the pigs had loss of signal in the electromyography during the procedure; only one pig had isolated transient decrease in amplitude and one increase in latency. One pig had transient vocal fold paresis in the group with activation on the nerve. Evaluation of the nerves by histology and immunohistochemistry did not show significant changes attributed to thermal injury. CONCLUSIONS: The use of ultrasonic energy close to the RLN is safe, provided that activation time does not exceed the necessary time to safely transect the tissue.

Vocal cord paralysis predicted by neural monitoring electrophysiologic changes with recurrent laryngeal nerve compressive neuropraxic injury in a canine model.

BACKGROUND: Recurrent laryngeal nerve (RLN) injury is a known complication of thyroid/parathyroid surgery. Intraoperative nerve monitoring (IONM) has been used to gain more information regarding the functional status of the RLN intraoperatively; however, the electromyography (EMG) parameters of RLN after nontransection neuropraxic compressive injury remain unknown. METHODS: We developed a canine model to identify IONM EMG correlates of postoperative vocal cord paralysis (VCP) using a standardized method to simulate surgical RLN compression sufficient to cause VCP. RESULTS: Compression nerve injury decreased EMG amplitude and increased EMG latency, with a 60% increase in RLN threshold stimulation compared to preinjury values. If RLN amplitude decreases by 80% with an absolute amplitude of 300 µV or less in combination with a latency increase of 10% or more, then nerve injury and associated VCP is likely. CONCLUSION: These results may help surgeons to prognosticate postoperative neural function and intraoperative decision-making regarding contralateral thyroid surgery. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1341-E1350, 2016.

Intravenous mesenchymal stem cell therapy after recurrent laryngeal nerve injury: a preliminary study.

OBJECTIVES/HYPOTHESIS: Intravenous administration of mesenchymal stem cells (MSCs) has been recently shown to enhance functional recovery after stroke and spinal cord injury. The therapeutic properties of MSCs are attributed to their secretion of a variety of potent antiinflammatory and neurotrophic factors. We hypothesize that intravenous administration of MSCs after recurrent laryngeal nerve (RLN) injury in the rat may enhance functional recovery. STUDY DESIGN: Animal Research. METHODS: Twelve 250-gram Sprague-Dawley rats underwent a controlled crush injury to the left RLN. After confirming postoperative vocal fold immobility, each rat was intravenously infused with either green fluorescent protein-expressing MSCs or control media in a randomized and blinded fashion. Videolaryngoscopy was performed weekly. The laryngoscopy video recordings were reviewed and rated by a fellowship-trained laryngologist who remained blinded to the intervention using a 0 to 3 scale. RESULTS: At 1 week postinjury, the MSC-infused group showed a trend for higher average functional recovery scores compared to the control group (2.2 vs 1.3), but it did not reach statistical significance (P value of 0.06). By 2 weeks, however, both groups exhibited complete return of function. CONCLUSIONS: These pilot data indicate that with complete nerve transection by crush injury of the RLN in rat, there is complete recovery of vocal fold mobility at 2 weeks. At 1 week postinjury, animals receiving intravenous infusion of MSCs showed a trend for greater functional recovery, suggesting a potential beneficial effect of MSCs; however, this did not reach statistical significance. Therefore, no definite conclusions can be drawn from these data and further study is required. LEVEL OF EVIDENCE: N/A.

Reorganization of laryngeal motoneurons after crush injury in the recurrent laryngeal nerve of the rat.

Motoneurons innervating laryngeal muscles are located in the nucleus ambiguus (Amb), but there is no general agreement on the somatotopic representation and even less is known on how an injury in the recurrent laryngeal nerve (RLN) affects this pattern. This study analyzes the normal somatotopy of those motoneurons and describes its changes over time after a crush injury to the RLN. In the control group (control group 1, n = 9 rats), the posterior cricoarytenoid (PCA) and thyroarytenoid (TA) muscles were injected with cholera toxin-B. In the experimental groups the left RLN of each animal was crushed with a fine tip forceps and, after several survival periods (1, 2, 4, 8, 12 weeks; minimum six rats per time), the PCA and TA muscles were injected as described above. After each surgery, the motility of the vocal folds was evaluated. Additional control experiments were performed; the second control experiment (control group 2, n = 6 rats) was performed labeling the TA and PCA immediately prior to the section of the superior laryngeal nerve (SLN), in order to eliminate the possibility of accidental labeling of the cricothyroid (CT) muscle by spread from the injection site. The third control group (control group 3, n = 5 rats) was included to determine if there is some sprouting from the SLN into the territories of the RLN after a crush of this last nerve. One week after the crush injury of the RLN, the PCA and TA muscles were injected immediately before the section of the SLN. The results show that a single population of neurons represents each muscle with the PCA in the most rostral position followed caudalwards by the TA. One week post-RLN injury, both the somatotopy and the number of labeled motoneurons changed, where the labeled neurons were distributed randomly; in addition, an area of topographical overlap of the two populations was observed and vocal fold mobility was lost. In the rest of the survival periods, the overlapping area is larger, but the movement of the vocal folds tends to recover. After 12 weeks of survival, the disorganization within the Amb is the largest, but the number of motoneurons is similar to control, and all animals recovered the movement of the left vocal fold. Our additional controls indicate that no tracer spread to the CT muscle occurred, and that many of the labeled motoneurons from the PCA after 1 week post-RLN injury correspond to motoneurons whose axons travel in the SLN. Therefore, it seems that after RLN injury there is a collateral sprouting and collateral innervation. Although the somatotopic organization of the Amb is lost after a crush injury of the RLN and does not recover in the times studied here, the movement of the vocal folds as well as the number of neurons that supply the TA and the PCA muscles recovered within 8 weeks, indicating that the central nervous system of the rat has a great capacity of plasticity.

Tapia's syndrome after arthroscopic shoulder stabilisation under general anaesthesia and LMA.

BACKGROUND: Anaesthetic complications, albeit rare, still occur and may be severe and unanticipated, with significant morbidity. Extracranial ipsilateral palsy of the recurrent laryngeal and the hypoglossal nerves is known as the Tapia's syndrome. Damage to these nerves may result from displacement of the head during mask ventilation, endotracheal intubation, bronchoscopy or the use of a laryngeal mask airway (LMA). We describe unilateral paralysis of the muscles of the tongue and ipsilateral vocal cord due to a lesion of cranial nerves X and XII that occurred following LMA anaesthesia combined with plexus block. CASE REPORT: A 57-year-old man with a rupture of the right shoulder underwent arthroscopic shoulder stabilisation and internal fixation. General anaesthesia with aLMA was combined with an interscalene plexus block. After induction with propofol and fentanyl, a LMA was inserted with some difficulty without muscle relaxation. The cuff was inflated with 30 mL of air and further volumes of air until a "just-seal" pressure was obtained. The anaesthesia was maintained with sevoflurane in oxygen/air. The procedure was carried out in a semi-supine position with the head inclined slightly forward, and the upper body slightly elevated. Surgery lasted 55 min and anaesthesia 70 min. After surgery, the patient quickly regained consciousness and the LMA was removed when he was responding to commands and was able to fully open his mouth. During the immediate postoperative period, the patient's voice was hoarse but he breathed without difficulty. The following day, he developed dysphagia and slurred speech; on examination, paralysis of the left side of the tongue was found. The diagnosis of an acute injury to the hypoglossal and laryngeal recurrent nerves was made and the patient was transferred to the neurology clinic for further treatment. CONCLUSIONS: This rare complication reminds us not only of the importance of positioning during anaesthesia and surgery, but also of the need for careful and correct airway management. It could be probably prevented by careful insertion of an appropriate size LMA, and the use of low intracuff pressures and/or volumes.

Quantity and three-dimensional position of the recurrent and superior laryngeal nerve lower motor neurons in a rat model.

OBJECTIVES: We sought to elucidate the 3-dimensional position and quantify the lower motor neurons (LMNs) of the recurrent laryngeal nerve (RLN) and the superior laryngeal nerve (SLN) in a rat model. Quantification and mapping of these neurons will enhance the usefulness of the rat model in the study of reinnervation following trauma to these nerves. METHODS: Female Sprague-Dawley rats underwent microsurgical transection of the RLN, the SLN, or both the RLN and SLN or sham surgery. After transection, either Fluoro-Ruby (FR) or Fluoro-Gold (FG) was applied to the proximal nerve stumps. The brain stems were harvested, sectioned, and examined for fluorolabeling. The LMNs were quantified, and their 3-dimensional position within the nucleus ambiguus was mapped. RESULTS: Labeling of the RLN was consistent regardless of the labeling agent used. A mean of 243 LMNs was documented for the RLN. The SLN labeling with FR was consistent and showed a mean of 117 LMNs; however, FG proved to be highly variable in labeling the SLN. The SLN LMNs lie rostral and ventral to those of the RLN. In the sham surgical condition, FG was noted to contaminate adjacent tissues--in particular, in the region of the SLN. CONCLUSIONS: Fluorolabeling is an effective tool to locate and quantify the LMNs of the RLN and SLN. The LMN positions and counts were consistent when FR was used in labeling of either the RLN or the SLN. Fluoro-Gold, however, because of its tendency to contaminate surrounding structures, can only be used to label the RLN. Also, as previously reported, the SLN LMNs lie rostral and ventral to those of the RLN. This information results in further clarification of a rat model of RLN injury that may be used to investigate the effects of neurotrophic factors on RLN reinnervation.