Search

Introduction: Vagal nerve stimulator (VNS) implantation is a vital therapy for epilepsy refractory to other treatments; however, it is associated with a very high rate of voice changes. Relatively few of these patients are evaluated for vocal fold motion impairments. In this series, we evaluate 5 such patients with a novel phenotype of forced abduction with VNS stimulation., Methods: Retrospective case series., Results: Five patients with a VNS implant who underwent operative direct or in-office rigid laryngoscopy and had vocal fold motion impairment associated with VNS activation are included. All 5 patients had vocal fold mobility with VNS off and a fixed with activation. All patients exhibited vocal fold abduction with VNS activation. Patient 2 has since undergone laryngeal reinnervation, which helped her intermittent dysphonia but left a small glottic gap. A type 1 thyroplasty corrected this gap and improved her voice further. Patient 3 has undergone laryngeal reinnervation for which early results show improvement in perceptual and patient reported outcomes. Patients 4 and 5 have both undergone laryngeal reinnervation with improvement in voice., Conclusion: Previous reported cases of stimulated immobility associated with VNS use describe only adduction of the vocal fold. This series expands the previous work showing the VNS activation can also cause stimulated immobility in an abducted position, for which reinnervation and other medialization procedures offer promising treatment., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: To evaluate whether vocal function exercises (VFE) could be an adjunct treatment for patients with unilateral vocal fold paralysis (UVFP) who were not satisfied with their postoperative voices after reinnervation surgeries., Study Design: Retrospective., Methods: Medical records of the patients with UVFP who underwent laryngeal reinnervation between October 2011 and October 2014 were reviewed. Patients were classified into two groups: one received VFE according to patients' desire (VFE group) and the other did not have voice therapy (control group). Effects of VFE were assessed by vocal fold vibration (regularity, amplitude and glottal gap), aerodynamic measurements (maximum phonation time (MPT) and mean airflow rate (MFR)), GRBAS scale, acoustic parameters (pitch range, pitch perturbation and amplitude perturbation quotients (PPQ, APQ), and noise-to-harmonics ratio (NHR)) and subjective evaluation by patients (Voice Handicap Index-10 (VHI-10)). Phonatory function was also compared between the two groups at three time points: before reinnervation surgery, before VFE, and after VFE., Results: Thirty patients were enrolled (11 men, 19 women). The VFE group included eight patients, and 22 patients served as controls. In the VFE group, several parameters (amplitude, MPT, MFR, pitch range, APQ, and NHR) did not improve significantly after surgery, while all parameters examined improved significantly in the control group. After VFE, amplitude, glottal gap, MFR, B score, pitch range, and PPQ showed significant improvement, while the control group did not show a significant improvement except in VHI-10, during the corresponding period. Significant differences in G and B scores and VHI-10 between the two groups were observed at the third time point., Conclusions: VFE may be used as an adjunct treatment for patients with UVFP who are not satisfied with their voices after reinnervation surgery. However, phonatory function after VFE may not reach the same level as for those who are satisfied with their voices after reinnervation surgery., Competing Interests: CONFLICT OF INTEREST There is no conflict of interest to disclose., (Copyright © 2022 The Voice Foundation. Published by Elsevier Inc. All rights reserved.)

Objective: Postoperative recurrent laryngeal nerve paralysis is one of the complications of thyroid surgery, and the prevention and management of paralysis is an important issue for surgeons. In this study, in order to gain further understanding of recurrent laryngeal nerve paralysis after thyroid surgery, we analyzed and examined the usefulness of nerve stimulators for recurrent laryngeal nerve paralysis and the factors that may cause recurrent laryngeal nerve paralysis. Furthermore, in cases where transient recurrent laryngeal nerve paralysis occurred, we analyzed and examined the timing of improvement in vocal cord movement for each intraoperative finding and intraoperative operation that caused the paralysis., Methods: At the Department of Otorhinolaryngology Head and Neck Surgery, Sapporo Medical University Hospital, between January 2012 and December 2021, the subjects were 543 thyroid surgery cases (692 nerves) without preoperative paralysis or cancer nerve invasion performed. The relationship between postoperative transient and permanent paralysis of the recurrent laryngeal nerve was evaluated using univariate and multivariate analysis. The factors evaluated were gender, age, BMI, total thyroidectomy, benignity, malignancy, Graves' disease, using IIONM (intermittent intraoperative nerve monitoring), using CIONM (continuous intraoperative nerve monitoring), malignant tumor T3b or higher, with lateral neck dissection, and years of experience of the surgeon. Furthermore, by targeting 87 nerves with transient paralysis, surgical operations were divided into three groups: minor injury, major injury, and adhesion, and their relationship with the timing of postoperative vocal fold movement improvement was evaluated., Results: Permanent paralysis of the recurrent laryngeal nerve occurred in 12 nerves (1.7 %), and transient paralysis occurred in 100 nerves (14.5 %). Univariate analysis showed no association with each factor, but multivariate analysis showed that transient paralysis was significantly lower in men and in patients using IIONM. The improvement time for vocal cord paralysis was 2.8 months in the minor injury group, 4.5 months in the major injury group, and 3.2 months in the adhesion group, indicating a statistically significant difference between the minor injury group and the major injury group., Conclusion: This study suggests that the use of IIONM and gentle manipulation of women may prevent recurrent laryngeal nerve paralysis during thyroid surgery. In addition, understanding the period of nerve recovery for each operation for postoperative transient recurrent laryngeal nerve paralysis may contribute to patient explanations and determining the timing of therapeutic intervention for speech improvement surgery., (Copyright © 2024. Published by Elsevier B.V.)

Introduction: Recurrent laryngeal nerve palsy is a rare but important complication after endarterectomy (CEA). The impact on voice quality after this procedure is also important. The aim of the study was to assess voice quality and vocal cord function after CEA., Material and Methods: 200 patients were enrolled in the study. Inclusion criteria were indications for CEA and patient consent to the procedure. Endoscopic examination of the larynx was performed before the procedure, immediately after the procedure, on the 2nd day after the procedure, then 3 month and 6 months after the procedure. Voice was assessed by maximum phonation time (MPT), GRBAS scale, Voice Handicap Index (VHI) and the Voice-Related Quality of Life (V-RQOL) questionnaire., Results: In the study group, the results on the GRBAS scale were significantly worse and the average MPT was shorter compared to the control group. In the V-RQOL assessment, patients rated their voice as fair or good, significantly more often noticed that they had difficulty speaking loudly and being heard, and that they felt short of air when speaking. In VHI-30, the total score was significantly higher in the study group compared to the control group. Voice disorders after the procedure were reported by 68 patients, while a disorder of the recurrent laryngeal nerve was observed immediately after the procedure in 32 patients. Most vocal cord disorders were transient. Ultimately, 3% of patients were diagnosed with vocal cord paralysis., Conclusion: Cranial nerves paralysis, including the recurrent laryngeal nerve, are a common complication after CEA. Majority the paralysis is transient, but requires appropriate diagnostic and therapeutic procedures. Vocal cord evaluation is a non-invasive and widely available examination and should be performed pre- and postoperatively after all neck surgeries. The incidence of voice disorders after CEA significantly affects the quality of life of patients and requires voice rehabilitation and patient care with psychological support., Competing Interests: The authors report no conflicts of interest in this work., (© 2024 Dorobisz et al.)

Phonation critically depends on precise controls of laryngeal muscles in coordination with ongoing respiration. However, the neural mechanisms governing these processes remain unclear. We identified excitatory vocalization-specific laryngeal premotor neurons located in the retroambiguus nucleus (RAm VOC ) in adult mice as being both necessary and sufficient for driving vocal cord closure and eliciting mouse ultrasonic vocalizations (USVs). The duration of RAm VOC activation can determine the lengths of both USV syllables and concurrent expiration periods, with the impact of RAm VOC activation depending on respiration phases. RAm VOC neurons receive inhibition from the preBötzinger complex, and inspiration needs override RAm VOC -mediated vocal cord closure. Ablating inhibitory synapses in RAm VOC neurons compromised this inspiration gating of laryngeal adduction, resulting in discoordination of vocalization with respiration. Our study reveals the circuits for vocal production and vocal-respiratory coordination.

Objective: This systematic review aims to provide an overview of the current evidence-base for paediatric surgical reinnervation in unilateral and bilateral vocal fold palsies in clinical practice. We aim to assess patient demographics, surgical technique and pre- and post-operative outcome measures., Methods: A systematic literature review was performed and reported according to international PRISMA recommendations. A comprehensive search of PubMed, Embase, and Cochrane CENTRAL databases for relevant publications for all available dates with appropriate MESH search criteria was performed. Articles were categorised by four authors independently. A pooled summative analysis was carried out to allow review of demographic and outcome data., Results: Our systematic PRISMA approach resulted in 19 papers being selected for inclusion and analysis with 179 patients undergoing reinnervation (153 unilateral, 26 bilateral). The youngest patient was 1.9 years. Iatrogenic injury to recurrent laryngeal nerve most common aetiology (65.4% and 19.2% of unilateral and bilateral vocal fold palsies, respectively). Patent ductus arteriosus ligation was the single most common procedure resulting in unilateral vocal fold palsies (43.1% of cases). Statistically significant improvements in subjective and objective outcomes for both voice and swallowing were seen. Meta-analysis was able to be performed on the particularly evident improvements in GRBAS score and Maximum Phonation Time (MPT). GRBAS scores improved by 3.64 (p < 0.01, 95% CI 2.65 to 4.63). MPT showed a statistically significant improvement of 5.26 s (p < 0.05, 95% CI 4.28 to 6.24). No major complications were reported., Conclusion: The current published evidence on one-hundred and seventy-nine paediatric surgical reinnervation procedures demonstrates its role as a safe and effective treatment for both unilateral and bilateral vocal fold palsies. Anatomically it has been shown to improve vocal fold tone, bulk and position. Both post-operative voice and swallowing outcomes show improvement as well as associated quality of life measures., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Eliciting a normal electromyography signal has been the usual method to confirm the functional integrity of the recurrent laryngeal nerve during intraoperative nerve monitoring. Given that oscillations of the vocal cord can be detected with trans-laryngeal ultrasound when the ipsilateral recurrent laryngeal nerve is stimulated with the endotracheal tube in situ, we aimed to compare the accuracy and cost of this novel method with the conventional electromyography method., Methods: Consecutive patients who underwent elective thyroid, parathyroid or neck dissection procedures were included. The NIM-Neuro 3.0 system was used. Endotracheal tube-based surface electrodes were utilized for electromyography signal recording. Standard anesthetic technique was adopted. Recurrent laryngeal nerve integrity was verified by both detection methods (laryngeal ultrasound and electromyography) independently. Vocal cord function was validated by flexible direct laryngoscopy postoperatively. For each method, concurrence with flexible direct laryngoscopy was defined as "true-positive" or "true-negative," based on the presence or absence of vocal cord paresis. Accuracy was calculated as the sum of all true positives and negatives divided by the total of nerves-at-risk. The cost of each method was calculated., Results: One hundred and four patients were eligible. Total number of nerves-at-risk was 155. Based on flexible direct laryngoscopy findings, the test sensitivity, specificity, positive predictive value, and negative predictive value of intraoperative laryngeal ultrasound were 75.0%, 99.3%, 85.7%, and 98.6%, respectively, while those of electromyography were 87.5%, 98.0%, 70.0%, and 99.3%, respectively. The prognostic accuracy in laryngeal ultrasound versus electromyography was comparable (98.1% vs 97.4%). The cost of the laryngeal ultrasound per operation was less than electromyography ($82 vs $454)., Conclusion: Laryngeal ultrasound has a similar detection accuracy to electromyography during intraoperative nerve monitoring. Apart from being a cheaper alternative, laryngeal ultrasound may be useful when there is unexplained loss of electromyography signals during surgery and may play a role in the intraoperative nerve monitoring troubleshooting algorithm., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objectives: Laryngeal vibratory asymmetry occurring with paresis may result in a perceptually normal or abnormal voice. The present study aims to determine the relationships between the degree of vibratory asymmetry, acoustic measures, and perception of sound stimuli., Study Design: Animal Model of Voice Production, Perceptual Analysis of Voice., Methods: In an in vivo canine model of phonation, symmetric and asymmetric laryngeal vibration were obtained via graded unilateral recurrent laryngeal nerve (RLN) stimulation simulating near paralysis to full activation. Phonation was performed at various contralateral RLN and bilateral superior laryngeal nerve stimulation levels. Naïve listeners rated the perceptual quality of 182 unique phonatory samples using a visual sort-and-rate task. Cepstral peak prominence (CPP) was calculated for each phonatory condition. The relationships among vibratory symmetry, CPP, and perceptual ratings were evaluated., Results: A significant relationship emerged between RLN stimulation and perceptual rating, such that sound samples from low RLN levels were preferred to those from high RLN levels. When symmetric vibration was achieved at mid-RLN stimulation, listeners preferred samples from symmetric vibration over those from asymmetric vibration. However, when symmetry was achieved at high RLN levels, a strained voice quality resulted that listeners dispreferred over asymmetric conditions at lower RLN levels. CPP did not have a linear relationship with perceptual ratings., Conclusions: Laryngeal vibratory asymmetry produces variable perceptual differences in phonatory sound quality. Though CPP has been correlated with dysphonia in previous research, its complex relationship with quality limits its usefulness as clinical marker of voice quality perception., Level of Evidence: NA, basic science Laryngoscope, 131:2740-2746, 2021., (© 2021 The American Laryngological, Rhinological and Otological Society, Inc.)

Needle biopsy is a well-established component in the evaluation of thyroid nodules. The biopsy is usually performed with an ultrasound guidance and consists of either fine-needle aspiration or core needle biopsy. Although these terms are often used interchangeably, their difference is important. To our knowledge, we discuss the first reported case of biopsy-proven laryngeal nerve injury and permanent vocal fold paralysis following ultrasound-guided core biopsy of the thyroid. We advocate this complication be discussed as part of the consent process.

New neurons born in the adult brain undergo a critical period soon after migration to their site of incorporation. During this time, the behavior of the animal may influence the survival or culling of these cells. In the songbird song system, earlier work suggested that adult-born neurons may be retained in the song motor pathway nucleus HVC with respect to motor progression toward a target song during juvenile song learning, seasonal song restructuring, and experimentally manipulated song variability. However, it is not known whether the quality of song per se, without progressive improvement, may also influence new neuron survival. To test this idea, we experimentally altered song acoustic structure by unilateral denervation of the syrinx, causing a poor quality song. We found no effect of aberrant song on numbers of new neurons in HVC, suggesting that song quality does not influence new neuron culling in this region. However, aberrant song resulted in the loss of left-side dominance in new neurons in the auditory region caudomedial nidopallium (NCM), and a bilateral decrease in new neurons in the basal ganglia nucleus Area X. Thus new neuron culling may be influenced by behavioral feedback in accordance with the function of new neurons within that region. We propose that studying the effects of singing behaviors on new neurons across multiple brain regions that differentially subserve singing may give rise to general rules underlying the regulation of new neuron survival across taxa and brain regions more broadly., Competing Interests: The authors have declared that no competing interests exist.

Objectives/hypothesis: Applying the principles of misdirected nerve regeneration to the larynx, Roger Crumley in 1989 coined the term laryngeal synkinesis (LS) which he later (2000) classified into 4 types (type I - good voice, type II - involuntary twitches and poor voice, type III - adduction during inspiration, type IV - abduction during phonation). Neurophysiological data were not available for all LS patients at that time. The current study was undertaken to utilize and test the Crumley classification for a clinical interrater comparison and, secondly, compare predicted with actual laryngeal electromyography (LEMG) results., Study Design: Descriptive study., Methods: Laryngoscopic and LEMG data of patients with unilateral vocal fold paralysis (VFP) of 6 months duration or longer were combined for retrospective evaluation. Forty-five data sets were available for laryngoscopic classification by two local laryngologists and by Roger Crumley. Twenty-three data sets with complete thyroarytenoid (TA) and posterior cricoarytenoid (PCA) - EMG data were used to compare predicted with actual LEMG results., Results: Local laryngologists were able to classify 24 of 45, Crumley 30 of 45 cases into one of the 4 synkinesis types. There was substantial agreement between examiners (Cohens Kappa 0.66 [P < .001]). Comparison of predicted and actual LEMG data showed only moderate agreement. EMG sykinesis rates were lower in TA than in PCA and highest in Crumley type I cases., Conclusion: The Crumley classification is helpful in describing and understanding synkinesis. It does not always correlate predictably with actual LEMG data. A complete LEMG mapping of all intrinsic muscles may improve understanding of chronic VFP., Level of Evidence: 4. Laryngoscope, 131:E1605-E1610, 2021., (© 2020 The Authors. The Laryngoscope published by Wiley Periodicals LLC on behalf of American Laryngological, Rhinological and Otological Society Inc, "The Triological Society" and American Laryngological Association (ALA).)

Objectives/hypothesis: Injection laryngoplasty of materials for unilateral vocal-fold paralysis has shown various results regarding the long-term stability of the injected material. We evaluated a fibrin-gel based cell suspension with autologous chondrocytes in-vitro and in-vivo as long-term-stable vocal-fold augmentation material in an animal model., Study Design: This study compises an in vitro cell-culture part as well as an in vivo animal study with New Zealand White Rabbits., Methods: In in-vitro experiments, auricular chondrocytes harvested from 24 New Zealand White Rabbits cadavers were cultivated in pellet cultures to evaluate cartilage formation for 4 weeks using long-term-stable fibrin gel as carrier. Injectability and injection volume for the laryngoplasty was determined in-vitro using harvested cadaveric larynxes. In-vivo 24 Rabbits were biopsied for elastic cartilage of the ear and autologous P1 cells were injected lateral of one vocal cord into the paraglottic space suspended in a long-term-stable fibrin gel. Histologic evaluation was performed after 2, 4, 12, and 24 weeks., Results: During 12-week pellet culture, we found extracellular matrix formation and weight-stable cartilage of mature appearance. In-vivo, mature cartilage was found in two larynxes (n = 6) at 4 weeks, in four (n = 6) at 12 weeks, and in five (n = 6) at 24 weeks mostly located in the paraglottic space and sometimes with spurs into the vocalis muscle. Surrounding tissue was often infiltrated with inflammatory cells. Material tended to dislocate through the cricothyroid space into the extraglottic surrounding tissue., Conclusions: A cell-based approach with chondrocytes for permanent vocal-fold augmentation has not previously been reported. We have achieved the formation of structurally mature cartilage in the paraglottic space, but this is accompanied by difficulties with dislocated material, deformation of the augmentation, and inflammation., Level of Evidence: N/A Laryngoscope, 131:E1624-E1632, 2021., (© 2020 The Authors. The Laryngoscope published by Wiley Periodicals LLC on behalf of The American Laryngological, Rhinological and Otological Society, Inc.)

Competing Interests: Declaration of competing interest There are no conflicts of interest.

Background: Early recognition of postoperative vocal cord palsy enhances postoperative care. Translaryngeal ultrasonography can assess vocal cord function accurately and noninvasively, but it is unclear whether it is feasible or accurate when done immediately after extubation in the recovery room owing to possible interference from laryngeal swelling. This study assessed the feasibility and accuracy of translaryngeal ultrasonography in this setting., Methods: Consecutive patients undergoing neck operations were subjected to translaryngeal ultrasonography and flexible direct laryngoscopy 1 day before and day 7 after thyroidectomy and parathyroidectomy. Translaryngeal ultrasonography was performed early in the recovery room immediately after extubation in the operating room. A standardized assessment protocol was used. Patient parameters were compared between those with assessable and unassessable vocal cords., Results: Sixty-five patients (91 recurrent laryngeal nerves-at-risk) were analyzed after excluding 2 male patients who failed preoperative translaryngeal ultrasonography. Fifty-six patients underwent thyroidectomy and 9 parathyroidectomy. The median age (range) was 57 (46-69); 44 (68%) were women. Sixty-one patients (94%) had assessable bilateral vocal cords on translaryngeal ultrasonography in the recovery room. Translaryngeal ultrasonography in the recovery room findings corresponded completely with day-7 findings on direct laryngoscopy. Long operative time was associated with nonassessable vocal cords on translaryngeal ultrasonography in the recovery room (P = .026)., Conclusion: Very early postoperative translaryngeal ultrasonography in the recovery room after neck surgery is highly feasible and accurate. Long operative time may hinder the use of translaryngeal ultrasonography in the recovery room., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objectives/hypothesis: Demonstration of voice improvement and long-term stability following nonselective unilateral laryngeal reinnervation (ULR) in patients with unilateral vocal fold paralysis (UVFP) and severe denervation. A subgroup of patients on whom ULR was performed as a salvage technique following unsuccessful medialization was analyzed separately., Study Design: Prospective cohort study., Methods: The ansa cervicalis-recurrent laryngeal nerve anastomosis technique was performed in all patients. Pre- and postoperative voice analysis included voice questionnaires, voice assessment by senior laryngologists using the Hirano Voice Scale, and computer-assisted voice analysis at defined time points over the course of 36 months. Laryngeal electromyography (LEMG) and spirometry were performed before and 1 year after ULR., Results: Significant linear improvement of mean voice quality over time was observed in the majority of parameters measured in 48 ULR patients and in eight ULR salvage patients. LEMG 1 year after ULR showed new recruitment. Mean voice quality remained stable during follow-up in all ULR patients and in the ULR salvage group., Conclusions: Nonselective ULR in UVFP is a reliable and stable therapeutic option for patients with high expectations concerning voice quality. The effect is stable in long-term results. It is also a viable option for patients in whom conventional voice surgery failed to improve voice quality. We therefore propose ULR as salvage option in UVFP., Level of Evidence: 2b Laryngoscope, 130:1756-1763, 2020., (© 2019 The American Laryngological, Rhinological and Otological Society, Inc.)

Importance: Bilateral vocal fold paralysis (BVFP) in pediatric patients is a challenging entity with multiple causes. Traditional approaches to managing BVFP include tracheostomy, arytenoidectomy, suture lateralization, cordotomy, and posterior cricoid enlargement. These interventions are used to create a stable airway but risk compromising voice quality., Objectives: To assess the use of bilateral selective laryngeal reinnervation (SLR) surgery to manage BVFP and restore dynamic function to the larynx in pediatric patients., Design, Setting, and Participants: In this case series performed at 2 tertiary care academic institutions, 8 pediatric patients underwent bilateral SLR to treat BVFP (5 patients with iatrogenic BVFP and 3 with congenital BVFP) from November 2004 to August 2018 with follow-up for at least 1.5 years., Interventions: Bilateral selective laryngeal reinnervation surgery., Main Outcomes and Measures: Flexible laryngoscopy findings, subjective and objective measures of voice quality, subjective swallowing function, and decannulation in patients who were previously dependent on a tracheostomy tube., Results: Participants included 6 boys and 2 girls with a median age of 9.3 (range, 2.2 to 18.0) years at the time of surgery. All 8 patients were decannulated; 6 patients had preoperative tracheostomies and 2 had perioperative tracheostomies. Voice quality, as measured using the GRBAS (grade, roughness, breathiness, asthenia, strain) scale, improved in 6 of 8 patients after reinnervation, and swallowing was not impaired in any patients. In 2 patients, GRBAS scale scores remained the same before and after surgery. Inspiratory vocal fold abduction was observed on both sides in 5 patients and on 1 side in 2 patients, with no active abduction observed in 1 patient. The follow-up period was more than 5 years in 7 of 8 patients and at least 1.5 years in all patients., Conclusions and Relevance: Bilateral SLR appears to be a promising treatment option for children with BVFP; it is currently the only option, to our knowledge, with the potential to restore abductor and adductor vocal fold movement. In patients with complete paralysis, this procedure may provide a strategy for airway management and restoration of the dynamic function of the larynx. It could be considered as a first-line technique before endolaryngeal or airway framework procedures, which carry a risk of compromising voice quality.

Objectives/hypothesis: To evaluate differences in cortical-basal ganglia-cerebellar functional connectivity between treated unilateral vocal fold paralysis (UVFP) and healthy control cohorts using resting-state functional magnetic resonance imaging (RS-fMRI)., Study Design: Cross-sectional., Methods: Ten UVFP study patients treated by type I thyroplasty and 12 control subjects underwent RS-fMRI on a 3-Tesla scanner to evaluate differences in functional connectivity of whole-brain networks. Spontaneous RS-fMRI data were collected using a gradient echo planar pulse sequence, preprocessed, and analyzed to compare seed-to-voxel maps between the two cohorts. Seeds were placed in the caudate, putamen, and globus pallidus divisions of the basal ganglia in both hemispheres. Group contrasts were tested for statistical significance using two-tailed unpaired t tests corrected for multiple comparisons with a cluster false discovery rate threshold of P < .05., Results: UVFP patients demonstrated increased connectivity between both caudate nuclei and the precuneus, a node of the default mode network, compared to healthy controls. Both caudate nuclei also showed decreased connectivity with the left cerebellar hemisphere. The putamen and globus pallidus divisions of the basal ganglia were not abnormally connected to other brain structures., Conclusions: UVFP patients treated by type I thyroplasty exhibited long-term alterations of cortical-basal ganglia-cerebellar networks thought to be important for self-referential voice quality awareness and learning processes that compensate for changes to the paralyzed hemilarynx. This pilot study on relatively small cohorts adds to growing evidence for persistent central nervous system changes in treated UVFP. Replication studies with larger numbers of subjects will be essential to validate and extend findings., Level of Evidence: 3b Laryngoscope, 130:460-464, 2020., (© 2019 The American Laryngological, Rhinological and Otological Society, Inc.)

Injection laryngoplasty as used in this chapter is synonymous with the term "injection augmentation." Injection augmentation is a technique designed to enhance glottic closure in patients with glottic insufficiency, or failure of glottic closure, by injecting material into the lateral aspect of the vocal fold to move the vibrating surface to the midline. This type of injection augments the vocal fold and improves glottic closure. Injection augmentation originated over 100 years ago. However, the current indications, techniques, and materials have changed significantly. Paralysis, defined as loss of function due to neu-rological injury, remains a common cause of glottic insufficiency. In cases of paralysis, nerve function to adduct the vocal folds for voice production and coughing is interrupted, bilaterally or unilaterally, and the glottis becomes insufficient. While unilateral vocal fold paralysis remains the most common indication for vocal fold injection augmentation, due to the development of newer injectable materials and less invasive injectable techniques, surgeons routinely perform injection augmentation for glottic insufficiency due to other causes such as vocal fold paresis, vocal fold atrophy, presbylarynx, vocal fold scar, and soft tissue loss. Additionally, there is an increasing performance of vocal fold injection in the awake patient. This allows for immediate feedback and reduced anesthetic risk. Outcomes assessment for injection augmentation remains varied by lack of consensus and large-scale studies to identify the factors most instrumental in documenting optimal results. We review the history of injection laryngoplasty, the indications for injection, choice of injectate, outcomes, complications, and future directions of injection laryngoplasty for augmentation., (© 2020 S. Karger AG, Basel.)

Bilateral vocal fold paralysis presents as their complete or partial immobilisation. The median or paramedian position of vocal folds contributes to the narrowing of the airway at the level of the glottis and manifests as inspiratory dyspnoea. For many years iatrogenic injury of recurrent laryngeal nerves during thyroidectomy has been viewed as the most common underlying reason. It is very often a lifethreatening condition requiring not only corticosteroid administration and intubation, which only constitute a short-term symptomatic therapy, but also surgical intervention, including tracheostomy. The most common surgical methods implemented in bilateral vocal fold paralysis include posterior cordectomy, arytenoidectomy, and, more and more commonly, re-innervation. Other techniques used in restoring airway patency include laterofixation, botulinum toxin injection, and laryngeal stimulation, which is still under research. Stem cell and gene therapy are also being researched. Notably, the main purpose of surgical treatment is the provision of airway patency with the preservation of the phonatory and protective functions of the larynx.

Vocal fold immobility can be either unilateral or bilateral and partial or complete. The aim of this chapter is to discuss the management of unilateral paresis using medialization thyroplasty with or without arytenoid adduction as a means of treating neurogenic causes as opposed to mechanical fixation. Medialization thyroplasty is an open surgical procedure that is performed under local or general anesthesia. Essentially, it aims to close the glottic gap, approximating both vocal folds together and thereby allowing for restoration of the efficiency of the larynx. The glottic gap results from atrophy of the affected vocal fold and in so doing results in glottic insufficiency which causes voice breathiness, strain, fatigue, aspiration, and swallowing difficulties that make up the bulk of symptoms associated with this condition. Unlike injection laryngoplasty, medialization thyroplasty does not increase the "bulk" of the atrophic vocal fold but merely brings the fold closer to its unaffected partner. Besides the obvious lateralization, there is occasionally a third dimensional component to the affected fold. The slipping and prolapse forward of the arytenoid cartilage due to atrophy of the muscles supporting it and the natural declination of the facet joint it rests on cause a vertical drop of the level of the affected vocal fold that may not be remedied with the medialization procedure, hence requiring arytenoid adduction. Although attempts to medialize the vocal fold have been described in the past with limited access, the basic premise of creating a window in the thyroid cartilage remains central. The differences between materials used, their respective strengths and weaknesses, the pitfalls and pearls in achieving a good closure and improvement in voice, swallow, and safety of the airway are all discussed accordingly., (© 2020 S. Karger AG, Basel.)

Objective: To evaluate the extent of airway improvement and voice quality in patients with bilateral vocal fold paralysis (BVFP) who underwent selective laryngeal reinnervation surgery., Methods: Seven patients with BVFP caused by thyroid surgeries were enrolled. They underwent selective laryngeal reinnervation surgery. Videostroboscopy data, voice perceptual data (grade [G]), acoustic data, laryngeal electromyography data, and pulmonary function test data were obtained preoperatively and postoperatively., Results: Videostroboscopic videos showed that six patients could achieve moderate-to-maximal abduction in the bilateral vocal folds during inspiration, whereas all patients achieved adduction in the bilateral vocal folds during phonation at 4 to 7 months postoperatively. G score was decreased significantly versus preoperative values (P < 0.05), and vocal functional parameters were improved significantly at 12 months postoperatively (P < 0.05). The aerodynamic parameter of maximum phonation time was significantly longer than the preoperative value (P < 0.05). Most parameters in pulmonary function test recovered to normal reference levels as early as 3 months postoperatively, whereas maximal inspiratory pressure (PImax) values were still slightly lower than normal levels 12 months after surgery. All of these parameters improved significantly versus preoperative values. Electromyographic data at 12 months postoperatively showed full interference potentials in bilateral posterior cricoarytenoid muscles during inspiration and full interference potentials in bilateral thyroarytenoid muscles during phonation in all patients. Moderate electric potentials were seen in left interarytenoid muscle in one failed patient., Conclusion: This new selective laryngeal reinnervation procedure can achieve physiological movements of the bilateral vocal folds in selected patients with BVFP., Level of Evidence: 4. Laryngoscope, 129:2669-2673, 2019., (© 2019 The American Laryngological, Rhinological and Otological Society, Inc.)

Purpose: Laryngeal electromyography (LEMG) has been considered as gold standard in diagnostics of vocal fold movement impairment, but is still not commonly implemented in clinical routine. Since the signal interpretation of LEMG signals (LEMGs) is often a subjective and semi-quantitative matter, the goal of this study was to evaluate the inter-rater reliability of neurolaryngologists on LEMGs of volitional muscle activity., Methods: For this study, 52 representative LEMGs of 371 LEMG datasets were selected from a multicenter registry for a blinded evaluation by 7 experienced members of the neurolaryngology working group of the European Laryngological Society (ELS). For the measurement of the observer agreement between two raters, Cohen's Kappa statistic was calculated. For the interpretation of agreements of diagnoses among the seven examiners, we used the Fleiss' Kappa statistic., Result: When focusing on the categories "no activity", "single fiber pattern", and "strongly decreased recruitment pattern", the inter-rater agreement varied from Cohen's Kappa values between 0.48 and 0.84, indicating moderate to near-perfect agreement between the rater pairs. Calculating with Fleiss' Kappa, a value of 0.61 showed good agreement among the seven raters. For the rating categories, the Fleiss' Kappa value ranged from 0.52 to 0.74, which also showed a good agreement., Conclusion: A good inter-rater agreement between the participating neurolaryngologists was achieved in the interpretation of LEMGs. More instructional courses should be offered to broadly implement LEMG as a reliable diagnostic tool in evaluating vocal fold movement disorders in clinical routine and to develop future algorithms for therapy and computer-assisted examination.

Background: Schwannomas, benign tumors arising from neurolemmocytes, are the most common type of peripheral nerve tumors. Extracranial schwannomas are most often found in the parapharyngeal space, commonly involving the vagus nerve to cervical sympathetic trunk. Vagal schwannomas present several unique clinical and therapeutic challenges., Methods: A comprehensive literature review was conducted on 197 articles reporting 235 cases of cervical vagal schwannomas. Presenting symptoms, treatment approach, and postoperative outcomes were recorded and analyzed., Results: Vagal schwannomas commonly present as asymptomatic neck masses. When they become symptomatic, surgical resection is the standard of care. Gross total resection is associated with higher postoperative morbidity compared to subtotal resection. Initial reports using intraoperative nerve monitoring have shown improved nerve preservation. Recurrence rates are low., Conclusion: The combination of intermittent nerve mapping with novel continuous vagal nerve monitoring techniques may reduce postoperative morbidity and could represent the future standard of care for vagal schwannoma treatment., (© 2019 Wiley Periodicals, Inc.)

We present the case of an 89-year-old man with 3-month history of hoarseness and no other significant clinical manifestations. Flexible laryngoscopy revealed a paralyzed left vocal cord, and contrast-enhanced computed tomography showed a thoracic dissecting aortic aneurysm of the distal aortic arch and proximal descending aorta. The aortic aneurysm was repaired through implantation of an endovascular stent graft, and the patient was discharged uneventfully after a week. The false lumen was completely thrombosed, and the patient had a partial resolution of hoarseness at the 1-year follow-up., (Copyright © 2019 Elsevier Inc. All rights reserved.)

A physiologically-based scheme that incorporates inherent neurological fluctuations in the activation of intrinsic laryngeal muscles into a lumped-element vocal fold model is proposed. Herein, muscles are activated through a combination of neural firing rate and recruitment of additional motor units, both of which have stochastic components. The mathematical framework and underlying physiological assumptions are described, and the effects of the fluctuations are tested via a parametric analysis using a body-cover model of the vocal folds for steady-state sustained vowels. The inherent muscle activation fluctuations have a bandwidth that varies with the firing rate, yielding both low and high-frequency components. When applying the proposed fluctuation scheme to the voice production model, changes in the dynamics of the system can be observed, ranging from fluctuations in the fundamental frequency to unstable behavior near bifurcation regions. The resulting coefficient of variation of the model parameters is not uniform with muscle activation. The stochastic components of muscle activation influence both the fine structure variability and the ability to achieve a target value for pitch control. These components can have a significant impact on the vocal fold parameters, as well as the outputs of the voice production model. Good agreement was found when contrasting the proposed scheme with prior experimental studies accounting for variability in vocal fold posturing and spectral characteristics of the muscle activation signal. The proposed scheme constitutes a novel and physiologically-based approach for controlling lumped-element models for normal voice production and can be extended to explore neuropathological conditions.

The song of the adult male zebra finch is a well-studied example of a learned motor sequence. Song bouts begin with a variable number of introductory notes (INs) before actual song production. Previous studies have shown that INs progress from a variable initial state to a stereotyped final state before each song. This progression is thought to represent motor preparation, but the underlying mechanisms remain poorly understood. Here, we assessed the role of sensory feedback in the progression of INs to song. We found that the mean number of INs before song and the progression of INs to song were not affected by removal of two sensory feedback pathways (auditory or proprioceptive). In both feedback-intact and feedback-deprived birds, the presence of calls (other non-song vocalizations), just before the first IN, was correlated with fewer INs before song and an initial state closer to song. Finally, the initial IN state correlated with the time to song initiation. Overall, these results show that INs do not require real-time sensory feedback for progression to song. Rather, our results suggest that changes in IN features and their transition to song are controlled by internal neural processes, possibly involved in getting the brain ready to initiate a learned movement sequence., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2019. Published by The Company of Biologists Ltd.)

Previous studies in animals and humans suggest the periaqueductal grey region (PAG) is a final integration station between the brain and laryngeal musculature during phonation. To date, a limited number of functional magnetic neuroimaging (fMRI) studies have examined the functional connectivity of the PAG during volitional human phonation. An event-related, stimulus-induced, volitional movement paradigm was used to examine neural activity during sustained vocalization in neurologically healthy adults and was compared to controlled exhalation through the nose. The contrast of vocalization greater than controlled expiration revealed activation of bilateral auditory cortex, dorsal and ventral laryngeal motor areas (dLMA and vLMA) (p < 0.05, corrected), and suggested activation of the cerbellum, insula, dorsomedial prefrontal cortex (dmPFC), amygdala, and PAG. The functionally defined PAG cluster was used as a seed region for psychophysiological interaction analysis (PPI) to identify regions with greater functional connectivity with PAG during volitional vocalization, while the above functionally defined amygdala cluster was used in an ROI PPI analysis. Whole-brain results revealed increased functional connectivity of the PAG with left vLMA during voicing, relative to controlled expiration, while trend-level evidence was observed for increased PAG/amygdala coupling during voicing (p = 0.07, uncorrected). Diffusion tensor imaging (DTI) analysis confirmed structural connectivity between PAG and vLMA. The present study sheds further light on neural mechanisms of volitional vocalization that include multiple inputs from both limbic and motor structures to PAG. Future studies should include investigation of how these neural mechanisms are affected in individuals with voice disorders during volitional vocalization., (Copyright © 2018. Published by Elsevier B.V.)

Primary muscle tension dysphonia (pMTD) is a voice disorder that occurs in the absence of laryngeal pathology. Dysregulated activity of the paralaryngeal muscles is considered the proximal cause; however, the central origin of this aberrant laryngeal muscle activation is unclear. The Trait Theory (Roy and Bless, 2000a,b) proposed that specific personality traits can predispose one to laryngeal motor inhibition and pMTD, and this inhibition is mediated by a hyperactive "behavioral inhibition system (BIS)" composed of limbic system structures (and associated prefrontal connections). This case study used functional magnetic resonance imaging to detect brain activation changes associated with successful management of pMTD, thereby evaluating possible neural correlates of this poorly understood disorder., Method: A 61-year-old woman with moderate-to-severe pMTD underwent functional magnetic resonance imaging scans before and immediately after successful treatment using manual circumlaryngeal techniques. Experimental stimuli were blocks of repeated vowel production and overt sentence reading., Results: Significantly greater activation was observed pre- versus posttreatment in all regions of interest during sentence production, that is, periaqueductal gray, amygdala, hypothalamus, anterior cingulate cortex, hippocampus, dorsolateral prefrontal cortex, Brodmann area 10, and premotor and inferior sensorimotor cortex., Conclusions: Our findings are compatible with overactivation of neural regions associated with the BIS (cingulate cortex, amygdala, hypothalamus, periaqueductal gray) and motor inhibition networks (eg, [pre-]supplementary motor area) along with the dorsolateral prefrontal cortex and medial prefrontal cortex. Heightened input from limbic regions combined with dysfunctional prefrontal regulation may interfere with laryngeal motor preparation, initiation, and execution thereby contributing to disordered voice in pMTD., (Copyright © 2019 The Voice Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: Laryngeal function requires neuromuscular activation of the intrinsic laryngeal muscles (ILMs). Rapid activation of the ILMs occurs in cough, laughter, and voice-unvoiced-voiced segments in speech and singing. Abnormal activation is observed in hyperfunctional disorders such as vocal tremor and dystonia. In this study, we evaluate the dynamics of ILM contraction., Study/design: Basic science study in an in vivo canine model., Methods: The following ILMs were stimulated: thyroarytenoid (TA), lateral cricoarytenoid/interarytenoid (LCA/IA), cricothyroid (CT), all laryngeal adductors (LCA/IA/TA), and the posterior cricoarytenoid (PCA). Neuromuscular stimulation was performed via the respective nerves at current levels needed to achieve maximum vocal fold posture change. Muscle contraction and posture changes were recorded with high speed video (HSV). HSV frames were then analyzed to measure response times required from the onset of muscle contraction to the time the vocal folds achieved maximum posture change., Results: In all muscles, the onset of posture change occurred within 10 to 12 milliseconds after neuromuscular stimulation. The average times ( ± standard deviation) to achieve final posture were as follows: TA 34.5 ± 6 ms (N = 15), LCA/IA 55 ± 12 ms (N = 14), recurrent laryngeal nerve 43 ± 8 ms (N = 18), CT 100.8 ± 17 ms (N = 26), and PCA 91.2 ± 8 ms (N = 3). Data distribution appeared normal., Conclusion: Results showed a difference in muscle activation time between different ILMs consistent with reported differences in muscle fiber composition. These data also provide an estimate of the limits of laryngeal contraction frequency in physiologic and pathologic laryngeal states., Level of Evidence: NA Laryngoscope, 129:E21-E25, 2019., (© 2018 The American Laryngological, Rhinological and Otological Society, Inc.)

Purpose: Beside recurrent laryngeal nerve (RLN), protection of the external branch of the superior laryngeal nerve (EBSLN) is required for complication-free thyroid surgery. This study investigates the contribution of intraoperative neuromonitoring (IONM) to identification and motor integrity of the EBSLN., Methods: This prospective study was performed on 245 EBSLNs in 147 patients with thyroid surgery. The rate of visual identification, contribution of IONM to functional localization, the rate and levels of recordable waveform amplitude from vocal cord (VC) movement were determined during surgery., Results: 164 (66.9%) EBSLNs were visually identified and additional 74 branches were functionally identified by IONM. Additional identification rate of IONM was 30.2%. Seven (2.9%) EBSLNs could not be identified during surgery. Cricothyroid muscle (CTM) twitch established functional integrity in 97.1% of EBSLNs. Electrophysiological stimulation of 151 (63.4%) EBSLNs created waveform amplitude >100 µV that mean amplitude level was calculated as 186 µV, and an amplitude >300 µV was recorded in 19 of 151 (12.6%) EBSLNs., Conclusions: In addition to visual identification, surgeons can functionally localize the EBSLN with the assistance of IONM that CTM twitch is a reliable evience for functional integrity of the EBSLN. In the majority of patients, stimulation of the EBSLN creates recordable waveform amplitude thus the EBSLN appears to be a second source of motor innervations for intrinsic laryngeal muscles.

Objective: The laryngeal adductor reflex (LAR) is an airway protective response triggered by sensory laryngeal receptors. It is unknown whether different glottic and supraglottic subsites vary in their reflex elicitation abilities. The recent discovery that a bilateral LAR is present in humans under general anesthesia upon laryngeal mucosal stimulation has enabled us to map the sensory receptor density for LAR elicitation at different laryngeal subsites. Our findings expose the likely mechanisms of LAR control., Methods: Prospective series of 10 patients undergoing laryngoscopy. Laryngeal subsites (epiglottic tip, membranous vocal fold, midventricular vocal fold, posterior supraglottis, epiglottic petiole) were stimulated via direct laryngoscopy with a bipolar probe. Vocal fold responses were recorded by endotracheal tube and hook wire electrodes, and visual observation., Results: Posterior supraglottic stimulation elicited bilateral LARs in all patients at all intensities. Membranous vocal folds, epiglottic petiole, and subglottis elicited no LAR. Ventricular fold and epiglottic tip responses converted from ipsi- to bilateral at high intensities., Conclusion: There are likely three checkpoints for control of the LAR in humans. These checkpoints protect against inappropriate LAR activation during volitional tasks without compromising airway protection: 1) topographical differences in receptor density with the highest density in subsites most likely to contact foreign substances; 2) absence of receptors in membranous vocal folds; and 3) central summation threshold for crossed interneuron activation at brainstem level where only strong intensity stimuli will elicit bilateral responses. Checkpoint dysfunction provides a novel framework to diagnose and treat disease processes, including aspiration, laryngospasm, and sudden infant death., Level of Evidence: 4. Laryngoscope, E365-E370, 2018., (© 2018 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives/hypothesis: Continuous intraoperative nerve monitoring (CIONM) during thyroidectomy is promising technology that may reduce the incidence of recurrent laryngeal nerve (RLN) injuries. However, the current technique for CIONM, in which a stimulating probe is placed on the vagus nerve, has not been widely adopted because of concerns regarding its invasiveness and safety. A new method with the lead positioned on the RLN may overcome these objections and promote greater adoption of CIONM. This study was conducted to serve as the first step in determining the safety and feasibility of an RLN-based CIONM approach., Study Design: Case series with planned data collection., Methods: Fifty patients scheduled to undergo thyroidectomy were enrolled. In all cases, after identification of the RLN, a lead designed for CIONM was placed on the nerve. The lead was then left in place for a minimum of 2 minutes, and CIONM data were recorded. Laryngeal electromyographic (EMG) characteristics were assessed just before the lead was placed on the RLN and after it was removed. Pre- and postoperative fiberoptic laryngoscopy was performed to assess vocal cord function in all patients., Results: In 49 patients (98%), the probe was successfully positioned on the RLN, and CIONM data were generated. On average, 1.4 attempts per patient were required to properly place the lead. No accidental dislodgements of the lead occurred during the experiments. No patients demonstrated significant EMG changes from baseline after manipulation and stimulation of the RLN. The average CIONM time was 175.7 s (range, 138-212 s), and the average CIONM amplitude and latency were 675.2 µV (range, 211.0-1405.2 µV) and 1.8 ms (1.25-1.9), respectively. All patients had normal bilateral vocal cord function preoperatively and at the first postoperative visit., Conclusions: This study demonstrates the apparent safety and viability of a CIONM technique using a lead placed directly on the RLN. Future investigations are warranted of this promising method, which may promote more widespread adoption of CIONM during thyroidectomy to reduce RLN injuries., Level of Evidence: 4 Laryngoscope, 2018., (© 2018 The American Laryngological, Rhinological and Otological Society, Inc.)

Objective: Vocal fold paralysis is caused by injury to the recurrent laryngeal nerve (RLN). Current clinical measures of laryngeal innervation are often nonquantitative. Compound motor action potentials (CMAP) measure motor innervation. The goal of this study was to determine whether CMAP can quantify laryngeal innervation following acute nerve injury., Study Design: Animal study., Methods: Twelve canine hemilaryngeal preparations were used. The RLN was serially stimulated with increasing intensities until the nerve was maximally stimulated. The CMAP amplitude was measured for each intensity stimulation and correlated. Next, the RLN was incompletely transected, and the reduction in CMAP amplitude was correlated to the percentage of transected axons. The percentage of transected axons was determined using horseradish peroxidase (HRP) staining., Results: Combining all hemilaryngeal preparations, the submaximal stimulation of the RLN linearly correlated with the resultant CMAP amplitude (r = 0.83; 95% CI, 0.76-0.88). Following partial RLN transection, the percentage of remaining axons linearly correlated with the CMAP amplitude (r = 0.87; 95% CI, 0.34-0.98)., Conclusions: CMAP amplitude is a quantitative measure that may correlate with the degree of vocal fold innervation in canines. Following RLN injury, CMAP may help clinicians quantify the number of intact axons, assess the likelihood of recovery, and counsel patients on their prognosis.

The aim of this study was to investigate whether the transplantation of olfactory-ensheathing cells (OECs) could physiologically repair severely injured recurrent laryngeal nerve (RLN) in dogs. Adult Beagle dogs were surgically introduced with a 10-mm defect in the left RLN and transplanted with a nerve guide (NEUROLAC) containing dog olfactory mucosa-olfactory-ensheathing cells (OM-OECs) in matrigel. The effects of OM-OECs on the morphology, histology, and electrophysiology of the injured RLNs, glottis movement, and voice acoustics were comparatively studied. Two months after transplantation, the normal dogs (group N) had intact left RLNs that contained axons well organized as bundles, transmitted action potentials of high amplitudes without latent phases, and modulated glottis movement to produce normal voices. The RLN-damaged dogs transplanted with OM-OECs (group CTT) had pieces of nerves regenerated in the place of the defects, which contained fewer axons scattered in the internal nerve membrane and wrapped peripherally by the connective tissue, prevented the distal trunk of the defected RLN from shrinking, transmitted action potentials of lower amplitudes with latent phases, and modulated a slightly impaired glottis movement to produce voices with slight differences compared to the N dogs. The RLN-damaged dogs without OM-OECs (group NC) had no nerves generated at the defective or the damaged area, leading to a shrinkage in the enervated distal nerve trunks; a blockage in nerve pulse transit; a paralysis of the left vocal cords; an impaired glottis movement; and abnormal voices. Transplantation of OM-OECs promoted nerve regeneration, and the recoveries of glottises and voices in dogs with RLN injury.

Purpose: Voice problems are common after thyroidectomy. The aim of this study was to assess the voice related quality of life after thyroidectomy with neuromonitoring. The sociodemographic and treatment factors influencing the quality of voice after the operation were investigated., Methods: A total of 40 patients after thyroidectomy with neuromonitoring were enrolled into the study. The voice outcome was analyzed pre and postoperatively by two validated self-assessment questionnaires: Voice Handicap Index and Voice-Related Quality of Life survey., Results: All external branches of the superior laryngeal nerve were identified during the operation. There were no recurrent laryngeal nerve palsies. The mean total VHIs before and after thyroid operation were 1.2 [SD 2.564] and 2.8 [SD 6.944], respectively (p = 0.5). Preoperatively, the mean overall score for the V-RQOL was 99.6; postoperatively 98.7 (p = 0.05). A strong correlation between the V-score of the V-RQOL and O-score of the VHI before and after thyroidectomy was observed (both p < 0.001). There was no correlation between V-RQOL or VHI and sex, the kind of thyroid operations, diagnosis, thyroid function, the mean volume of the goitre, the presence of retrosternal position and the extent of thyroid operations (p > 0.05). A small correlation between the mean age of the patients and postoperative O-Score of the VHI (p = 0.007650) and between the mean age and postoperative V-Score for the V-RQOL (p = 0.00648) was observed., Conclusions: The use of neuromonitoring in thyroid surgery is beneficial for patients to improve voice quality. The identification and preservation of EBSLNs is crucial to eliminate altered voice after thyroidectomy.

Objective: Treatment options for symptomatic unilateral vocal fold paralysis (VFP) include vocal fold augmentation, laryngeal framework surgery, and laryngeal reinnervation. Laryngeal reinnervation (LR) has been suggested to provide "tone" to the paralyzed VF. This implies a loss of tone as a result of denervation without reinnervation. We performed laryngeal electromyography (LEMG) in patients with chronic VFP to understand the innervation status associated with a chronically paralyzed vocal fold., Study Design: Retrospective review of LEMG data in adult patients with chronic VFP from January 2009 to December 2014., Methods: LEMG was performed at least 6 months after-onset of VFP. Qualitative LEMG, quantitative LEMG, and adductory synkinesis testing were performed, and the parameters were collected., Results: Twenty-seven vocal folds were studied (23 unilateral VFP and 2 bilateral VFP). Average age was 59 ± 17 years. The median duration from recurrent laryngeal nerve injury to LEMG was 8.5 months (range 6-90 months). The majority of patients, 24 of 27 (89%), had motor unit potentials during phonation tasks on LEMG, and only 3 of 27 (11%) patients were electrically silent. Quantitative LEMG showed 287.8 mean turns per second (normal ≥ 400). Motor unit configuration was normal in 12 of 27 (44%), polyphasic in 12 of 27 (44%), and absent in the electrically silent patients. Adductory synkinesis was found in 6 of 20 (30%) patients., Conclusion: Chronic vocal fold paralysis is infrequently associated with absent motor-unit recruitment, indicating some degree of preserved innervation and/or reinnervation in these patients. LEMG should be part of the routine workup for chronic VFP prior to consideration of LR., Level of Evidence: 4. Laryngoscope, 128:1628-1633, 2018., (© 2018 The American Laryngological, Rhinological and Otological Society, Inc.)

In songbirds, the learning and maintenance of song is dependent on auditory feedback, but little is known about the presence or role of other forms of sensory feedback. Here, we studied the innervation of the avian vocal organ, the syrinx, in the zebra finch. Using a combination of immunohistochemistry, immunofluorescence and neural tracing with subunit B of cholera toxin (CTB), we analysed the peripheral and central endings of the branch of the hypoglossal nerve that supplies the syrinx, the tracheosyringeal nerve. In the syringeal muscles, we show the presence of numerous choline acetyl transferase-like immunoreactive en plaque motor endplates and substance P-like immunoreactive, thin and varicose free nerve endings. Substance P-like immunoreactive free nerve endings were also present in the luminal syringeal tissues, especially in the luminal epithelium of the trachea and pessulus. Also, by a combination of immunofluorescence and transganglionic tracing following injections of CTB in the tracheosyringeal nerve, we identified as central targets of the syringeal receptors the caudolateral part of the interpolaris subnucleus of the descending trigeminal tract, a caudolateral region of the nucleus tractus solitarius, and a lateral band of the principal sensory trigeminal nucleus. Further studies are required to determine the sensory modalities of these receptors and the connections of their specific synaptic targets., (© 2017 Wiley Periodicals, Inc.)

Classical understanding of the function of the pharyngeal plexus in humans is that it relies on both motor branches for innervation of the majority of pharyngeal muscles and sensory branches for the pharyngeal wall sensation. To date there has been no reported data on the role of the pharyngeal plexus in vocal cord innervation. The aim of this study is to evaluate whether or not the plexus pharyngeus contributes to the innervation of the vocal cords. One hundred twenty-five sides from 79 patients (59 female, 20 male) undergoing thyroid surgery with intraoperative neuromonitoring were prospectively evaluated. While vocal cord function was evaluated with endotracheal tube surface electrodes, cricothyroid and cricopharyngeal muscle electromyographic recordings were obtained with a pair of needle electrodes. The ipsilateral pharyngeal plexus, external branch of the superior laryngeal nerve, and recurrent laryngeal nerve were stimulated with a monopolar probe at 1 mA. With stimulation of the plexus pharyngeus on 125 operated sides, positive electromyographic waveforms were detected from five ipsilateral vocal cords (accounting for 3.2% of all vocal cords monitored and 6.3% of patients). The mean EMG amplitude of the vocal cords with stimulation of the plexus pharyngeus was 147 ± 35.5 μV (range 110-203). In one case, the long latency time of 19.8 ms correlated with innervation by the glottic closure reflex pathway. The short latencies seen in the other four cases [3.9 ± 1.1 ms (range 3.2-5.5)] correlated with direct innervation. In some cases, the plexus pharyngeus may contribute to vocal cord innervation by reflex or direct innervation patterns in humans.

Objectives: The aim was to investigate the clinical and electromyographic characteristics of patients with unilateral vocal fold paralysis (UVFP) combined with lower cranial nerve injury., Study Design: This is a case series with chart review., Methods: Among 368 patients with idiopathic UVFP, 31 patients (8.4%) were eventually diagnosed with lower cranial nerve palsy after examinations of the head and neck, radiology, and electromyogram (EMG). The clinical and electromyographic characteristics of these patients were analyzed., Results: Of the 31 patients, 27 patients exhibited obvious abnormal lower cranial nerve injury physical signs, and 4 patients showed atypical physical signs, identified by EMG. Ultimately, 41.9% (13/31) were diagnosed with idiopathic causes, 38.7% (12/31) with intracranial or skull-base lesions on radiology, 12.9% (4/31) with lower cranial neuritis, and 6.4% (2/31) with radiation-induced lower cranial nerve palsy. Among the cranial lesions, lesions of the jugular foramen region were the most common (50%, 6/12). All 26 patients who underwent EMG tests were confirmed to have vagus nerve impairments (11 complete and 15 incomplete) and accessory nerve impairments (16 complete and 10 incomplete), whereas only 13 patients (50%) exhibited hypoglossal nerve injuries (5 complete and 8 incomplete)., Conclusions: For patients with clinically "idiopathic" UVFP, physical examinations of the lower cranial nerves are essential screening procedures. For patients with abnormal or suspicious physical signs, radiology should be performed to detect possible cranial or cervical lesions. EMG tests were strongly recommended to identify suspicious lower cranial nerve injury and its severity, and may help to predict the prognosis., (Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.)

Postoperative paralysis of the vocal cords resulting from intraoperative surgical injury of the recurrent laryngeal nerve is one of the most serious complications of elective thyroid surgery. The chance of injury is reduced by using intraoperative neuromonitoring (IONM). This educational report describes a case of IONM failure resulting from residual muscle relaxation that was restored by administration of sugammadex. It discusses possible pharmacology explanations and provides recommendations for how to prevent this situation in daily practice.

Objective: To evaluate the effect of transcutaneous electrical nerve stimulation (TENS) with and without tongue trills in women with vocal nodules., Study Design: Randomized, prospective, comparative intra-subject study., Methods: A total of 60 women aged 18-55 years were included. Visual-perceptual assessment of laryngeal configuration, auditory-perceptual assessment of voice quality, acoustic analyses, and self-assessment of phonation effort were assessed after TENS. Sixty participants participants were randomized into two experimental groups: (1) subjects receiving TENS (EG1), (2) subjects receiving TENS plus tongue trills (EG2). The control group was composed of 15 subjects of EG1 and 15 subjects of EG2. The TENS condition involved electrostimulation for 20 minutes. Audio and video perceptual assessments were performed by three speech therapists with expertise in voice; all were blinded to the experimental conditions. The acoustic parameters included were fundamental frequency, jitter, and shimmer during sustained phonation. Subjects also reported the degree of vocal effort before and after TENS., Results: TENS applied alone or combined with tongue trills aided in glottal closure and in improved comfort during phonation. When the TENS was administered with tongue trills, roughness of voice quality improved., Conclusion: TENS applied alone or combined with tongue trills was associated with improved glottal closure and phonation comfort. TENS associated with tongue trills yielded improved voice quality., (Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.)

Sensory receptors are distributed throughout the oral cavity, pharynx, and larynx. Laryngeal sensitivity is crucial for maintaining safe swallowing, thus avoiding silent aspiration. Morphologic description of different receptor types present in larynx vary because of the study of many different species, from mouse to humans. The most commonly sensory structures described in laryngeal mucosa are free nerve endings, taste buds, muscle spindles, glomerular and corpuscular receptors. This study aimed at describing the morphology and the distribution of nerve endings in premature newborn glottic region. Transversal serial frozen sections of the whole vocal folds of three newborns were analyzed using an immuno-histochemical process with a pan-neuronal marker anti-protein gene product 9.5 (PGP 9.5). Imaging was done using a confocal laser microscope. Nerve fiber density in vocal cord was calculated using panoramic images in software Morphometric Analysis System v1.0. Some sensory structures, i.e. glomerular endings and intraepithelial free nerve endings were found in the vocal cord mucosa. Muscle spindles, complex nerve endings (Meissner-like, spherical, rectangular and growing) spiral-wharves nerve structures were identified in larynx intrinsic muscles. Nervous total mean density in vocal cord was similar in the three newborns, although they had different gestational age. The mean nerve fiber density was higher in the posterior region than anterior region of vocal cord. The present results demonstrate the occurrence of different morphotypes of sensory corpuscles and nerve endings premature newborn glottic region and provide information on their sensory systems., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Head and neck squamous cell carcinoma is the sixth leading cause of cancer worldwide. The most common risk factors are carcinogens (tobacco, alcohol), and infection of the human papilloma virus. Surgery is still considered as the treatment of choice in case of head and neck cancer, followed by a reconstructive surgery to enhance the quality of life in the patients. However, the widespread use of artificial implants does not provide appropriate physiological activities and often cannot act as a long-term solution for the patients. Here we review the applicability of multiple stem cell types for tissue engineering of cartilage, trachea, vocal folds and nerves for head and neck injuries. The ability of the cells to self-renew and maintain their pluripotency state makes them an attractive tool in tissue engineering., Competing Interests: The authors declare that they have no competing interests.

Objectives/hypothesis: Nerbridge (Toyobo Co., Ltd., Osaka, Japan) is a novel polyglycolic acid (PGA) tube that is filled with collagen fibers and that facilitates nerve fiber expansion and blood vessel growth. It is biocompatible and commercially available, with governmental approval for practical use in Japan. We hypothesized that the PGA-collagen tube would promote regeneration of the recurrent laryngeal nerve (RLN). This hypothesis was examined in a rat axotomy model of the RLN., Study Design: Prospective animal study., Methods: The axotomy model was established by transection of the left RLN in adult Sprague-Dawley rats. The cut ends of the nerve were bridged using Nerbridge (Toyobo Co., Ltd.) with a 1-mm gap (tube-treatment group) or direct sutures (sutured-control group). Left vocal fold mobility, nerve conduction velocity, morphology, and histology were assessed after 15 weeks., Results: Fifteen weeks after treatment, nerve fiber connections were observed macroscopically in both groups, and more clear myelinated fibers and better prevention of laryngeal muscle atrophy were observed in the tube-treatment group compared with the sutured-control group. However, vocal fold movement recovery was not observed in either group, and the conduction velocity of the RLN did not differ between the two groups., Conclusions: Better nerve regeneration was observed in the tube-treatment group. The combination therapy with molecular or gene therapy might be an effective strategy to improve vocal fold movement. The PGA-collagen tube has the potential to promote regeneration of the RLN and to be a scaffold for drug administration in these combination therapies., Level of Evidence: N/A. Laryngoscope, 126:E233-E239, 2016., (© 2015 The American Laryngological, Rhinological and Otological Society, Inc.)

Objective: The compound motor action potential (CMAP) is the summated action potential from multiple muscle fibers activated by a single nerve impulse. The utility of laryngeal muscle CMAP for quantifying innervation following recurrent laryngeal nerve (RLN) injury was investigated., Method: In a series of 21 canine hemi-laryngeal preparations, RLNs were exposed and a stimulating electrode placed. Maximum CMAP amplitudes and area under the curve from the thyroarytenoid (TA) muscles were obtained at baseline and at 6 months following injury to the RLN. Injury mechanisms included crush, stretch, cautery, and complete transection with microsuture repair., Results: Prior to injury, baseline CMAP amplitudes and area under the curve were 15.81 mV and 15.49mVms, respectively. Six months following injury, CMAP amplitude and area under curve were 105.1% and 102.1% of baseline for stretch, 98.7% and 112.7% for crush, 93.3% and 114.3% for cautery. The CMAP amplitude and area under the curve in the transection/repair group had a 54.3% and 69.4% recovery, respectively, which were significantly different than baseline (P < .01, P < .05). These values were correlated with vocal fold motion., Conclusion: The CMAP is a measure of vocal fold innervation. The technique could be further developed for clinical and experimental applications., (© The Author(s) 2016.)