Recurrent Laryngeal Nerve Lesion Research Articles

Management of Giant Thyroid Tumors in Patients with Multiple Comorbidities in a Tertiary Head and Neck Surgery Center.

Background/Objectives: The thyroid gland can represent the seat of development for giant tumors exceeding 10 cm in diameter. A retrospective analysis on 21 cases of giant thyroid tumors with comorbidities, operated in the ENT Department of the Bucharest University Emergency Hospital has been conducted. Methods: Giant benign tumors accounted for 28.57% of the cases studied and reached gigantic volumes in an average time interval of 3 years, with an average resection piece weight of 318 g. Malignant tumors accounted for 71.43%, with an average duration of evolution of 7 years, with an average resection piece weight of 581 g. Results: Dysphagia was present in all patients, dyspnea in 47.61% and dysphonia in 38.09% of cases. Total thyroidectomy is the gold standard in giant thyroid tumors, associated with radical neck dissection, extended to groups VI and VII in malignant tumors. In 10 of 11 cases of giant malignant thyroid tumors (90.90%), without anaplastic thyroid carcinoma, the survival at 5 years after multimodal oncologic treatment was favorable. Anticoagulant treatment increased the risk of postoperative reversible recurrent laryngeal nerve lesion. Conclusions: The management of giant thyroid tumors in patients with multiple comorbidities needs a multidisciplinary team including endocrinologist, radiologist, anesthesiologist, pathologist, ENT surgeon, thoracic surgeon, oncologist and radiotherapist.

Surgical treatment of unilateral laryngeal paralysis by selective reinnervation in thyroid surgery

State of the problem: One of the complications in thyroid surgery is a lesion of RLN which can be bilateral with a violation of respiratory function of the larynx and unilateral, in which the first priority is a violation of vocal function of the larynx. The most effective treatment for paralysis of the larynx is the method of laryngeal reinnervation, which can be non-selective, which is usually used in unilateral laryngeal paralysis and promotes reinnervation of both abductors and laryngeal adductors. Selective reinnervation is selectively focuses on the reinnervation of individual target muscles, so it is more often used in bilateral laryngeal paralysis. But despite this, it was used in unilateral laryngeal paralysis during surgery on the thyroid gland during intentional resection of the anterior branch of RLN with partial invasion of its tumour process. Aim: evaluation of the results of surgical treatment unilateral laryngeal paralysis by the method selective reinnervation in thyroidectomy. Materials and Methods: clinical case results of patient A. 15 years old with papillary thyroid cancer and metastases to regional lymph nodes of the neck (T4aN1M0) with absence disorders of laryngeal motility before surgery were analyzed. Examination of the larynx and voice examination were performed before surgery, 2-3 days and 6,12 months after surgery. Changes of laryngoscopic images and evaluation of the Indicators: maximum pho- nation time, fundamental frequency, noise to harmonic ratio, Jitter (loc), Shimmer (loc), Voice Handicap Index-30 (VHI-30), completed version of Jacobcon B. Results: Considering extralaryngeal bifurcation of the recurrent laryngeal nerve (RLN) and invasion of the tumor into the adductive branch of RLN on the left, its dissection was performed and end-to-end neuroanastomosis was formed, completed is selective laryngeal reinnervation. In the immediate postoperative period, patients complained of voice disorders. Study of voice parameters corresponded to severe voice disorders. Partial resumption of the mobility of the larynx and voice function was after 6 months. The signs of the laryngoscopic picture and the spectral analysis of the voice corresponded to the indicators before the operation after 12 months Сonclusions 1. Primary selective reinnervation of the larynx can be used to treat unilateral laryngeal paralysis under the following conditions: extralaryngeal branching of the recurrent laryngeal nerve (bifurcation), lesion of only one of its branches, which will provide sufficient coaxiality to perform anastomosis "end-to-end" and preservation electrical integrity of another branch. 2. This method allows you to restore the motility of the denervated vocal folds and the main indicators of the voice. 3. Given only one clinical case of treatment of unilateral laryngeal paralysis by selective reinnervation, this technique needs further study and refinement.

Preoperative Visualized Ultrasound Assessment of the Recurrent Laryngeal Nerve in Thyroid Cancer Surgery: Reliability and Risk Features by Imaging

BackgroundPreoperative identification and visualization of tumor infiltration of the recurrent laryngeal nerve (RLN) in patients with thyroid cancer is important. The purpose of our study was to evaluate the reliability and feasibility of preoperative assessment by ultrasound and to identify ultrasound imaging features potentially associated with tumor infiltration of the RLN.MethodsIn this prospective study, patients undergoing thyroid cancer surgery at our institution between August 2020 and January 2021 were included, and preoperative ultrasound visualization of the RLN and thyroid lesions was performed. RLN infiltration was also confirmed surgically in all cases. Five patients with enlarged lymph nodes were selected to undergo injection of carbon nanoparticles to confirm the correctness of RLN identification by preoperative ultrasound. The repeatability of RLN assessment by ultrasound was evaluated by comparing the correlation between pre- and intraoperative, intra- and inter-group assessments. Parameters of normal RLNs according to age, sex, and body mass index were established. Finally, ultrasound imaging features of patients with RLN tumor infiltration were analyzed to identify potential risk predictors.ResultsAccording to the ultrasonic assessment, RLNs of 70 patients appeared normal, while 14 of those patients appeared to be infiltrated by tumors. During surgery, the 70 cases of normal RLNs were confirmed, but only 8 of the 14 suspected cases of infiltration were confirmed. In all five patients injected with carbon nanoparticles, the location of RLNs adjacent to the marked lymph nodes observed by surgeons corresponded to the RLN location identified by preoperative ultrasound. The repeatability of RLN estimation varied from moderate to excellent. There were no significant differences in cross-sectional area, width, or thickness of normal RLNs according to age, sex, or body mass index. Indistinct margin with tumor, incontinuous shape as ultrasound features by the analysis of patients with surgically confirmed RLN infiltration were associated with tumor invasion.ConclusionWe show that preoperative ultrasound can be applied to visualize the RLN and may help predict tumor infiltration of the RLN.

Neurolaryngology

Neurological and neurophysiological knowledge of neuromuscular diseases is combined in neurolaryngology with experience from laryngology. Laryngeal electromyography (LEMG) is the most important diagnostic and prognostic tool in neurolaryngology. It can be combined with diagnostic electrostimulation. Interest in LEMG today extends beyond the thyroarytenoid muscle to all accessible laryngeal muscles. LEMG should be performed and interpreted according to astandardized protocol. Main applications of LEMG are confirmation, topodiagnostic and prognostic assessment of vocal fold paralysis. It is possible to differentiate fresh from old recurrent laryngeal nerve lesions as well as mechanical vocal fold fixations from paralysis. Needle guidance for botulinum toxin injections in spasmodic dysphonia and for augmentation laryngoplasty can be supported by LEMG, but also by laryngeal ultrasound. The timing of therapy for temporary and permanent augmentations, thyroplasty and reinnervation surgery may be better defined with experience from neurolaryngology. The use of diagnostic neurostimulation can reveal any remaining active movement potential of avocal fold and thus help identify candidates for future laryngeal pacemaker treatments. Other topics in neurolaryngology include spasmodic dysphonia and underlying neurological diseases such as stroke, central vocal fold paralysis, essential tremor and Parkinson's disease. Laryngoscopic, clinical and LEMG characteristics of these diseases are presented.

A current view on recurrent laryngeal nerve injury in total thyroidectomy

Introduction: Recurrent laryngeal nerve damage during total thyroidectomy was, is, and probably will be in the near future the Achilles’ heel of total thyroidectomy. Material and method: To perform the research we used the PubMed database. The questions were conceived to respect the PICOS guidelines. The PRISMA checklist was used to filter the results. The search was structured following the words: „recurrent laryngeal nerve injury” AND „total thyroidectomy”. Results: A total of 60 papers were identified. We excluded 12 papers as they were duplicates. From the 48 papers left, another 4 could not be obtained. Another 3 papers from the 44 left were excluded due to the fact they were not written in English. One paper was excluded as the subject did not follow our research purpose. 40 papers were left for analysis and discussion. Conclusion: To prevent recurrent laryngeal nerve lesions, at the moment in the literature there is no consensus. Unintentional injury to the recurrent laryngeal nerve is predictable but not an avertible situation thus bilateral lesions still represent a dramatic situation across the world for the patients and the operating surgeon.

Muscle activity and kinematics show different responses to recurrent laryngeal nerve lesion in mammal swallowing.

Understanding the interactions between neural and musculoskeletal systems is key to identifying mechanisms of functional failure. Mammalian swallowing is a complex, poorly understood motor process. Lesion of the recurrent laryngeal nerve, a sensory and motor nerve of the upper airway, results in airway protection failure (liquid entry into the airway) during swallowing through an unknown mechanism. We examined how muscle and kinematic changes after recurrent laryngeal nerve lesion relate to airway protection in eight infant pigs. We tested two hypotheses: 1) kinematics and muscle function will both change in response to lesion in swallows with and without airway protection failure, and 2) differences in both kinematics and muscle function will predict whether airway protection failure occurs in lesion and intact pigs. We recorded swallowing with high-speed videofluoroscopy and simultaneous electromyography of oropharyngeal muscles pre- and postrecurrent laryngeal nerve lesion. Lesion changed the relationship between airway protection and timing of tongue and hyoid movements. Changes in onset and duration of hyolaryngeal muscles postlesion were less associated with airway protection outcomes. The tongue and hyoid kinematics all predicted airway protection outcomes differently pre- and postlesion. Onset and duration of activity in only one infrahyoid and one suprahyoid muscle showed a change in predictive relationship pre- and postlesion. Kinematics of the tongue and hyoid more directly reflect changes in airway protections pre- and postlesion than muscle activation patterns. Identifying mechanisms of airway protection failure requires specific functional hypotheses that link neural motor outputs to muscle activation to specific movements.NEW & NOTEWORTHY Kinematic and muscle activity patterns of oropharyngeal structures used in swallowing show different patterns of response to lesion of the recurrent laryngeal nerve. Understanding how muscles act on structures to produce behavior is necessary to understand neural control.

Recurrent laryngeal nerve management in transoral endoscopic thyroidectomy.

The mechanism of recurrent laryngeal nerve (RLN) injury was investigated during a TransOral Endoscopic Thyroidectomy Vestibular Approach (TOETVA). The function of 185 nerves at risk (NAR) was recorded with intermitted intraoperative neural monitoring (I-IONM). The RLN electromyography (EMG) was delineated during: (a) a pre-dissection vagal nerve stimulation; (b) a RLN stimulation at initial visualization; (c) at nerve dissection; and (d) at the final verification of the entire RLN route. The location, genesis, segmental or diffuse and the outcomes of RLN injuries were catalogued. Twelve nerves (6.4%) lost the EMG signal and the incidences of temporary and permanent RLN dysfunction were 5.9% and 0.5%. A disrupted point (type 1 injury) could be identified in 7/12 nerves (58%). Five (42%) nerve injuries were classified as global (type 2). Of the seven type 1 injuries, 3 lesions occurred at the RLN laryngeal entry point during the nerve identification. Four type 1 injuries were at the distal 1cm of the RLN course and during the early nerve dissection. No proximal (>2cm) injuries occurred. The mechanisms of the injuries were thermal (58%) during the energy-based device use at the ligament of Berry dissection or at the dividing small branches of the inferior thyroid artery. Two (16%) traction injuries occurred during the early nerve dissection. In 2 cases we could not elucidate the mechanism of RLN injury (16%) and 1 injury (8%) was caused by the connective tissue constricting band of. The thermal RLN lesions had longer recovery times. The RLN palsy occurs in TOETVA, even when combined with an endoscopic magnification, IONM, early nerve identification, cranial to caudal dissection and top-down view. The thermal RLN injury was the most frequent cause and all injuries occurred at the distal RLN course.

Swallow Safety is Determined by Bolus Volume During Infant Feeding in an Animal Model.

Feeding difficulties are especially prevalent in preterm infants, although the mechanisms driving these difficulties are poorly understood due to a lack of data on healthy infants. One potential mechanism of dysphagia in adults is correlated with bolus volume. Yet, whether and how bolus volume impacts swallow safety in infant feeding is unknown. A further complication for safe infant swallowing is recurrent laryngeal nerve (RLN) injury due to patent ductus arteriosus surgery, which exacerbates the issues that preterm infants face and can increase the risk of dysphagia. Here, we used a validated animal model feeding freely to test the effect of preterm birth, postnatal maturation and RLN lesion and their interactions on swallow safety. We also tested whether bolus size differed with lesion or birth status, and the relationship between bolus size and swallow safety. We found very little effect of lesion on swallow safety, and preterm infants did not experience more penetration or aspiration than term infants. However, term infants swallowed larger boluses than preterm infants, even after correcting for body size. Bolus size was the primary predictor of penetration or aspiration, with larger boluses being more likely to result in greater degrees of dysphagia irrespective of age or lesion status. These results highlight that penetration and aspiration are likely normal occurrences in infant feeding. Further, when comorbidities, such as RLN lesion or preterm birth are present, limiting bolus size may be an effective means to reduce incidences of penetration and aspiration.

The effect of preterm birth, recurrent laryngeal nerve lesion, and postnatal maturation on hyoid and thyroid movements, and their coordination in infant feeding

Movements of the hyoid and thyroid are critical for feeding. These structures are often assumed to move in synchrony, despite evidence that neurologically compromised populations exhibit altered kinematics. Preterm infants are widely considered to be a neurologically compromised population and often experience feeding difficulties, yet measuring performance, and how performance matures in pediatric populations is challenging. Feeding problems are often compounded by complications arising from surgical procedures performed to ensure the survival of preterm infants, such as damage to the recurrent laryngeal nerve (RLN) during patent ductus arteriosus correction surgery. Here, we used a validated infant pig model for infant feeding to test how preterm birth, postnatal maturation, and RLN lesion interact to impact hyoid and thyroid excursion and their coordination. We filmed infant pigs when feeding using videofluorscopy at seven days old (1–2 months human equivalent) and 17 days old (6–9 months human equivalent) and tracked movements of the hyoid and thyroid on both days. We found that preterm birth impacted the coordination between hyoid and thyroid movements, but not their actual excursion. In contrast, excursion of the two structures increased with postnatal age in term and preterm pigs. RLN lesion decreased thyroid excursion, and primarily impacted hyoid movements by increasing variation in hyoid excursion. This work demonstrates that RLN lesion and preterm birth have distinct, but pervasive effects on feeding performance in infants, and suggest that interventions targeted towards reducing dysphagia should be prescribed based off the etiology driving dysphagia, rather than the prognosis of dysphagia.

The Effect of Preterm Birth and Recurrent Laryngeal Nerve Lesion on Palatopharyngeal Arch Function During Feeding

Feeding in infant mammals requires the precise coordination of multiple oropharyngeal structures, including the palatopharyngeal arch. During a typical swallow, the activity of the palatopharyngeus muscle produces constriction of the arches and lowers the soft palate, which may be responsible for flipping of the epiglottis to cover the airway. Most research on the role of the palatopharyngeal arches in swallowing has been limited to pharyngeal manometry, which provides insight into the relative pressures in the oropharynx during swallowing. Studies using manometry in preterm infants, or in those with iatrogenic sequelae such as recurrent laryngeal nerve (RLN) damage, suggest differences in function, but not on how the structures in the oropharynx move to contribute to those changes in function. In this study, we assessed palatopharyngeal arch kinematics during feeding by using our validated infant pig model to determine the impact of birth status (preterm versus term), lesion status (lesioned RLN versus intact) and their interaction on feeding performance. We placed tantalum radio‐opaque beads into relevant anatomical structures of 16 infant pigs, including the palatopharyngeal arches, the tongue, the hard and soft palate, and the nose. We recorded feeding at both seven and 17 days postnatal via biplanar high‐speed videofluoroscopy (100fps) across a total of 584 swallows. Using XMALab, we tracked the three‐dimensional movement of the arches relative to a rigid body comprised of the markers in the hard palate and the nose. We then used custom MATLAB code to calculate the three‐dimensional excursion of the arches during a swallow, as well as the timing of constriction initiation, and the point of maximal constriction during a swallow. We found that preterm infants had more variable arch excursion than term infants, and RLN lesion increased excursion for both term and preterm infants although there were minimal differences in arch excursion within an age between term and preterm infants. Term infants also reached maximal arch constriction later than preterm infants, most likely due to their larger arch excursion and larger bolus volume. Lesion infants, both term and preterm, also had delayed maximal arch constriction during swallows, although day 17 term lesion infants reached maximal constriction earlier than term day 17 infants. Lesion resulted in delayed initiation of arch constriction, which did not change with age, although older term infants exhibited later arch constriction initiation than older preterm infants. Our results show that preterm birth and RLN lesion have distinct yet pervasive effects on infant feeding. Altered feeding performance in these neurologically compromised infants may be due in part to changes in the activity of the palatopharyngeal arches.Support or Funding InformationNIH R01HD088561

Swallow Safety in Infant Pigs With and Without Recurrent Laryngeal Nerve Lesion.

Aerodigestive coordination is critical for safe feeding in mammals, and failure to do so can result in aspiration. Using an infant pig model, we analyzed the impact of recurrent laryngeal nerve (RLN) lesion on aerodigestive coordination and swallow safety at two time points prior to weaning. We used high-speed videofluoroscopy to record 23 infant pigs longitudinally at two ages (7days, 17days) feeding on barium milk. We measured respiration with a plethysmograph and used the Infant Mammalian Penetration-Aspiration Scale (IMPAS) to identify unsafe swallows. We tested for changes in swallow safety longitudinally in control and lesion pigs, and whether there was any interaction between the four different groups. On postnatal day 7, lesioned pigs exhibited differences in the frequency distribution of IMPAS scores relative to control pigs on day 7, and 17day old lesion and control pigs. There were longitudinal changes in performance following RLN lesion through time, suggesting that the impact of RLN lesion decreases with time, as older lesioned pigs performed similarly to older control pigs. We found minimal differences in the impact of aerodigestive coordination on swallow safety, with shorter delays of inspiration onset reflecting higher rates of penetration in young lesioned pigs. Healthy pigs aspirated at a similar rate to those with an RLN lesion indicating that the occasional occurrence of dysphagia in infants may be a normal behavior.

Specific Vagus Nerve Lesion Have Distinctive Physiologic Mechanisms of Dysphagia

Swallowing is complex at anatomical, functional, and neurological levels. The connections among these levels are poorly understood, yet they underpin mechanisms of swallowing pathology. The complexity of swallowing physiology means that multiple failure points may exist that lead to the same clinical diagnosis (e.g., aspiration). The superior laryngeal nerve (SLN) and the recurrent laryngeal nerve (RLN) are branches of the vagus that innervate different structures involved in swallowing. Although they have distinct sensory fields, lesion of either nerve is associated clinically with increased aspiration. We tested the hypothesis that despite increased aspiration in both case, oropharyngeal kinematic changes and their relationship to aspiration would be different in RLN and SLN lesioned infant pigs. We compared movements of the tongue and epiglottis in swallows before and after either RLN or SLN lesion. We rated swallows for airway protection. Posterior tongue ratio of safe swallows changed in RLN (p = 0.01) but not SLN lesioned animals. Unsafe swallows post lesion had different posterior tongue ratios in RLN and SLN lesioned animals. Duration of epiglottal inversion shortened after lesion in SLN animals (p = 0.02) but remained unchanged in RLN animals. Thus, although SLN and RLN lesion lead to the same clinical outcome (increased aspiration), the mechanisms of failure of airway protection are different, which suggests that effective therapies may be different with each injury. Understanding the specific pathophysiology of swallowing associated with specific neural insults will help develop targeted, disease appropriate treatments.

Feasibility criteria for total thyroidectomy in outpatient surgery

IntroductionFrance is pursuing a policy of cutting healthcare costs, and outpatient surgery is one of the objectives of this policy. Thyroid surgery could be suitable for outpatient management, provided there is an appropriate patient selection process. The aim of this study was to assess the risk factors for postoperative complications in total thyroidectomy (TT). DesignA single-center observational study was carried out from January 2010 to December 2015. MethodCorrelations between, on the one hand, age, gender, obesity, history of surgery, antiplatelet and/or anticoagulation treatment, the surgeon's experience, surgery time, repeated lymph node dissection, and surgical indication (cancer, lymphocytic thyroiditis, Graves’ disease or multinodular goiter) and, on the other hand, onset of postoperative complications (postoperative hypocalcemia, uni- or bi-lateral lesions of the recurrent laryngeal nerves, and premature compressive hematoma) were assessed. ResultsFour hundred and twenty-four consecutive TTs were included. 85 patients showed postoperative hypocalcemia (20.04%), 18 recurrent laryngeal nerve lesion (4.25%), and 4 compressive cervical hematoma (0.94%). Overall morbidity was 24.06%. Risk factors identified for postoperative hypocalcemia comprised: female gender [OR=3.2584; 95%CI (1.5500–7.7515); P=0.0036], surgery time [OR=1.0095; 95%CI (1.0020–1.0172); P=0.0129], and surgical indication for benign adenoma [OR=5.0642; 95%CI (1.7768–14.5904); P=0.0022]. None of the study variables emerged as risk factors for recurrent laryngeal nerve lesion. Repeated dissection increased the risk of re-do surgery for compressive hematoma [OR=25.1373; 95%CI (0.8468–32.2042); P=0.0347]. ConclusionSurgery time, female gender, repeated dissection and total thyroidectomy for benign adenoma are risk factors that should be considered in decision-making for performing TT on an outpatient basis.

Post-thyroidectomy Hypocalcemia - Risk Factors and Management.

The complications of thyroidectomy vary from hypocalcemia and recurrent laryngeal nerve lesions to injury of vocal folds, local hematoma, cysts, granuloma. Post-operative hypocalcemia has an incidence of 1.2-40%. Permanent hyoparathyroidism is registered in 3% of cases. This is a brief narrative review focusing on the levels of calcium after performing a thyroidectomy and the need of calcium supplements under these circumstances. This complication, even it seems rather harmless at first, in fact it represents an important contributor to hospitalization delay and, especially for severe forms, to poor quality of life, including the risk of life threatening episodes. Devascularisation of parathyroid glands in addition to injury or dissection causes hypoparathyroidism. Hypocalcemia risk differs with sex (females have a higher risk), lymph node dissection (it increases the risk), it differs with type of thyroidectomy (larger dissections have a higher risk; also the intervention for recurrent goitre and second intervention for post-operatory bleeding increase the risk of hypocalcemia; while Basedow disease is probably at higher risk than multinodular goitre among benign conditions) and the duration of procedure. Pre-operatory low calcium, parathormon (PTH), 25-hydroxivitamin D increases the risk. The calcium drop rate matters as well: a decrease of 1 mg/dL calcium over 12 hours after surgery is independently correlated with the risk of symptomatic hypocalcemia. Early post-operatory PTH and calcium are best predictors for the need of oral calcium supplements. Routine post-operatory calcium and vitamin D supplementation statistically significant decreases the risk of developing transitory hypocalcemia and acute complications compare to calcium alone supplements or no supplements. In cases of hypoparathyroidism calcitriol is preferred.

Impact of recurrent laryngeal nerve lesion on oropharyngeal muscle activity and sensorimotor integration in an infant pig model.

The successful performance of a swallow requires dynamic integration between a wide range of sensory inputs and muscle activities to produce the coordinated kinematics of oropharyngeal structures. Damage to the recurrent laryngeal nerve (RLN) produces dysphagia in infants, with food or liquid entering the airway despite this nerve having minimal direct sensory or motor connections to the act of swallowing, apart from vocal fold closure. Previous results have demonstrated that a complete RLN lesion disrupts both performance and kinematics before initiation of the pharyngeal swallow in infants. We tested the hypothesis that a RLN lesion produces changes in the normal activity of oral floor, tongue, and infrahyoid muscles during a swallow. We recorded swallowing in our validated infant pig model, with synchronous high-speed imaging and fine-wire, chronic electromyography. We found changes in the timing, duration, and amplitude of the motor pattern in an array of muscles that are supplied by several different cranial and cervical nerves. Some of these changes in muscle activity are associated with the preparatory aspects of bolus aggregation or movement and so occur before the pharyngeal swallow. Taken with previous biomechanical results, these patterns suggest an intricate brain stem sensorimotor integration that occurs as part of a swallow. In particular, the execution of oral motor function is changed as a result of this simple lesion. NEW & NOTEWORTHY Damage to the recurrent laryngeal nerve compromises swallowing despite an absent or minimal contribution to either the motor or sensory aspects of this function. This study documents EMG changes, following RLN lesion, to non-RLN innervated muscles that are active during swallowing in an infant model. Some of these muscles fire before the pharyngeal swallow and are associated with the preparatory aspects of bolus aggregation and movement, suggesting important sensorimotor integration at a brain stem level.

Maturation of the Coordination Between Respiration and Deglutition with and Without Recurrent Laryngeal Nerve Lesion in an Animal Model.

The timing of the occurrence of a swallow in a respiratory cycle is critical for safe swallowing, and changes with infant development. Infants with damage to the recurrent laryngeal nerve, which receives sensory information from the larynx and supplies the intrinsic muscles of the larynx, experience a significant incidence of dysphagia. Using our validated infant pig model, we determined the interaction between this nerve damage and the coordination between respiration and swallowing during postnatal development. We recorded 23 infant pigs at two ages (neonatal and older, pre-weaning) feeding on milk with barium using simultaneous high-speed videofluoroscopy and measurements of thoracic movement. With a complete linear model, we tested for changes with maturation, and whether these changes are the same in control and lesioned individuals. We found (1) the timing of swallowing and respiration coordination changes with maturation; (2) no overall effect of RLN lesion on the timing of coordination, but (3) a greater magnitude of maturational change occurs with RLN injury. We also determined that animals with no surgical intervention did not differ from animals that had surgery for marker placement and a sham procedure for nerve lesion. The coordination between respiration and swallowing changes in normal, intact individuals to provide increased airway protection prior to weaning. Further, in animals with an RLN lesion, the maturation process has a larger effect. Finally, these results suggest a high level of brainstem sensorimotor interactions with respect to these two functions.

Laryngeal nerve morbidity in 1.273 central node dissections for thyroid cancer

AimWe assess the prevalence and mechanism of recurrent laryngeal nerve (RLN) injury in central neck dissection (CND) for thyroid cancer. MethodsCND 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. Results49/1.273NAR (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. ConclusionsDuring 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.

Laryngeal EMG: Preferential damage of the posterior cricoarytenoid muscle branches especially in iatrogenic recurrent laryngeal nerve lesions.

Laryngeal electromyography (LEMG) of the thyroarytenoid (TA) muscle alone may not be sufficient in all patients to characterize or prove a recurrent laryngeal nerve (RLN) lesion in cases of vocal fold immobility. LEMG of the posterior cricoarytenoid (PCA) muscle may provide additional information. Retrospective review. Between 2008 and 2016, 339 patients in our laryngeal paralysis clinic were examined by transcutaneous needle TA-LEMG and, if tolerated, by PCA-LEMG. LEMGs were rated and compared according to criteria of the European Laryngological Society. Etiology was categorized as iatrogenic, noniatrogenic, or malignancy related. A total of 282 out of 339 patients had a partial or complete RLN or vagal nerve lesion: 178 iatrogenic, 74 noniatrogenic, and 30 because of nerve involvement by malignancies. Of paralytic vocal folds, 35.7% had normal or near-normal TA innervation, whereas corresponding PCA traces (if present) were pathologic in 94.6%. Comparing pairs of TA and PCA-LEMGs in paralysis of less than 4 months duration showed a predominance of PCA branch injuries in iatrogenic lesions (71.7 %), while in noniatrogenic lesions this was less pronounced (44.4%). In the few malignancy cases, there was an almost even distribution. Synkinetic reinnervation was earlier in iatrogenic RLN lesions. PCA-LEMG was better in proving an RLN lesion than TA-EMG alone. Our findings suggest etiology-dependent differences in the TA/PCA lesion pattern. To confirm this, larger sample sizes are needed. A preferential damage to PCA innervation in iatrogenic lesions could be relevant for further improvements of intraoperative neuromonitoring. 4. Laryngoscope, 128:1152-1156, 2018.

LVC Timing in Infant Pig Swallowing and the Effect of Safe Swallowing.

Recurrent laryngeal nerve (RLN) injury in neonates, a complication of head and neck surgeries, leads to increased aspiration risk and swallowing dysfunction. The severity of resulting sequelae range from morbidity, such as aspiration pneumonia, to mortality from infection and failure to thrive. The timing of airway protective events including laryngeal vestibule closure (LVC) is implicated in aspiration. We unilaterally transected the RLN in an infant pig model to observe changes in the timing of swallowing kinematics with lesion and aspiration. We recorded swallows using high-speed video-fluoroscopic swallow studies (VFSS) and scored them using the Infant Mammalian Penetration and Aspiration Scale (IMPAS). We hypothesized that changes would occur in swallowing kinematics (1) between RLN lesion and control animals, and (2) among safe swallows (IMPAS 1), penetration swallows (IMPAS 3), and aspiration swallows (IMPAS 7). We observed numerous changes in timing following RLN lesion in safe and unsafe swallows, suggesting pervasive changes in the coordination of oropharyngeal function. The timing of LVC, posterior tongue, and hyoid movements differed between pre- and post-lesion in safe swallows. Posterior tongue kinematics differed for post-lesion swallows with penetration. The timing and duration of LVC and posterior tongue movement differed between aspiration swallows pre- and post-lesion. After lesion, safe swallows and swallows with aspiration differed in timing of LVC, laryngeal vestibule opening, and posterior tongue and hyoid movements. The timing of thyrohyoid muscle activity varied with IMPAS, but not lesion. Further study into the pathophysiology of RLN lesion-induced swallowing dysfunction is important to developing novel therapies.

Relationship Between Laryngeal Electromyography and Video Laryngostroboscopy in Vocal Fold Paralysis

The objective of this study was to better define the relationship of laryngeal electromyography and video laryngostroboscopy in the diagnosis of vocal fold paralysis. Retrospective diagnostic cohort study with cross-sectional data analysis METHODS: Data were obtained from 57 patients with unilateral vocal fold paralysis who attended a large tertiary voice referral center. Electromyographic findings were classified according to recurrent laryngeal nerve, superior laryngeal nerve, and high vagal/combined lesions. Video laryngostroboscopy recordings were classified according to the position of the immobile fold into median, paramedian, lateral, and a foreshortened/hooded vocal fold. The position of the paralyzed vocal fold was then analyzed according to the lesion as determined by electromyography. The recurrent laryngeal nerve was affected in the majority of cases with left-sided lesions more common than right. Vocal fold position differed between recurrent laryngeal and combined vagal lesions. Recurrent laryngeal nerve lesions were more commonly associated with a laterally displaced immobile fold. No fold position was suggestive of a combined vagal lesion. The inter-rater reliability for determining fold position was high. Laryngeal electromyography is useful in diagnosing neuromuscular dysfunction of the larynx and best practice recommends its continued implementation along with laryngostroboscopy. While recurrent laryngeal nerve lesions are more likely to present with a lateral vocal fold, this does not occur in all cases. Such findings indicate that further unknown mechanisms contribute to fold position in unilateral paralysis.