RESUMO
Voice production has been an area of interest in science since ancient times, and although advancing research has improved our understanding of the anatomy and function of the larynx, there is still little general consensus on these two topics. This review aims to outline the main developments in this field and highlight the areas where further research is needed. The most important hypotheses are presented and discussed highlighting the four main lines of research in the anatomy of the human larynx and their most important findings: (1) the arrangement of the muscle fibers of the thyroarytenoid muscle is not parallel to the vocal folds in the internal part (vocalis muscle), leading to altered properties during contraction; (2) the histological structure of the human vocal cords differs from other striated muscles; (3) there is a specialized type of heavy myosin chains in the larynx; and (4) the neuromuscular system of the larynx has specific structures that form the basis of an intrinsic laryngeal nervous system. These approaches are discussed in the context of current physiological models of vocal fold vibration, and new avenues of investigation are proposed.
Assuntos
Músculos Laríngeos , Prega Vocal , Voz , Humanos , Músculos Laríngeos/anatomia & histologia , Músculos Laríngeos/fisiologia , Músculos Laríngeos/inervação , Voz/fisiologia , Prega Vocal/anatomia & histologia , Prega Vocal/fisiologia , Laringe/anatomia & histologia , Laringe/fisiologia , AnimaisRESUMO
OBJECTIVES/HYPOTHESIS: Recurrent laryngeal nerve injury diagnosed as idiopathic or due to short-term surgery-related intubation exhibits a higher incidence of left-sided paralysis. While this is often attributed to nerve length, it is hypothesized there are asymmetric differences in the expression of genes related to neuromuscular function that may impact reinnervation and contribute to this laterality phenomenon. To test this hypothesis, this study analyzes the transcriptome profiles of the intrinsic laryngeal muscles (ILMs), comparing gene expression in the left versus right, with particular attention to genetic pathways associated with neuromuscular function. STUDY DESIGN: Laboratory experiment. METHODS: RNA was extracted from the left and right sides of the rat posterior cricoarytenoid (PCA), lateral thyroarytenoid (LTA), and medial thyroarytenoid (MTA), respectively. After high-throughput RNA-Sequencing, 88 samples were organized into 12 datasets according to their age (P15/adult), sex (male/female), and muscle type (PCA/LTA/MTA). A comprehensive bioinformatics analysis was conducted to compare the left-right ILMs across different conditions. RESULTS: A total of 774 differentially expressed genes were identified across the 12 experimental groups, revealing age, sex, and muscle-specific differences between the left versus right ILMs. Enrichment analysis of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways implicated several genes with a left-right laryngeal muscle asymmetry. These genes are associated with neuronal and muscular physiology, immune/inflammatory response, and hormone control. CONCLUSION: Bioinformatics analysis confirmed divergent transcriptome profiles between the left-right ILMs. This preliminary study identifies putative gene targets that will characterize ILM laterality. LEVEL OF EVIDENCE: N/A Laryngoscope, 134:3741-3753, 2024.
Assuntos
Perfilação da Expressão Gênica , Músculos Laríngeos , Músculos Laríngeos/inervação , Animais , Masculino , Ratos , Feminino , Perfilação da Expressão Gênica/métodos , Traumatismos do Nervo Laríngeo Recorrente/genética , Transcriptoma , Ratos Sprague-DawleyRESUMO
Objective:To analyze the characteristics of vocal fold movement and glottic closure in patients with laryngeal neurogenic injury. Methods:A total of 185 patients with vocal fold paralysis diagnosed by laryngeal electromyography as neurogenic damage to cricothyroid muscle, thyreoarytenoid muscle and posterior cricoarytenoid muscle were enrolled, they were divided into unilateral vocal fold paralysis group and bilateral vocal fold paralysis group, respectively, and superior laryngeal paralysis group, recurrent laryngeal nerve paralysis group and vagal nerve paralysis group according to nerve injury. The characteristics of vocal fold movement and glottic closure were analyzed under strobe laryngoscope. The qualitative evaluation of vocal fold movement was fixed vocal fold, reduced vocal fold movement and normal vocal fold movement, and the qualitative evaluation of glottic closure was glottic closure and glottic imperfection. The results were analyzed statistically. Results:The proportion of normal, reduced and fixed vocal fold motion in bilateral vocal fold paralysis group was significantly different from that in unilateral vocal fold paralysis groupï¼P<0.05ï¼, the composition of normal and reduced vocal fold motion in bilateral vocal fold paralysis groupï¼47.70%ï¼ was significantly greater than that in unilateral vocal fold paralysis groupï¼12.27%ï¼. There was no significant difference between the proportion of glottic closure and glottic imperfecta in bilateral vocal fold paralysis group and unilateral vocal fold paralysis groupï¼P<0.05ï¼. The proportion of decreased vocal fold motion in superior laryngeal nerve paralysis groupï¼50.00%ï¼ was higher than that in recurrent laryngeal nerve paralysis groupï¼9.32%ï¼ and vagal nerve paralysis groupï¼9.00%ï¼. The proportion of decreased and fixed vocal fold motion in superior laryngeal nerve paralysis group, recurrent laryngeal nerve paralysis group and vagal nerve paralysis group was statistically significantï¼P<0.05ï¼.There was no significant difference in glottic closure among the three groupsï¼P<0.05ï¼. Conclusion:Vocal fold movement characteristics of patients with laryngeal neurogenic injury were mainly vocal fold fixation, or normal or weakened vocal fold movement. There may be missed diagnosis of unilateral vocal fold paralysis in clinical practice. In half of the patients with superior laryngeal nerve palsy, vocal fold movement is characterized by vocal fold fixation.
Assuntos
Paralisia das Pregas Vocais , Prega Vocal , Humanos , Paralisia das Pregas Vocais/fisiopatologia , Paralisia das Pregas Vocais/etiologia , Prega Vocal/fisiopatologia , Masculino , Feminino , Eletromiografia , Músculos Laríngeos/fisiopatologia , Músculos Laríngeos/inervação , Pessoa de Meia-Idade , Adulto , Glote/fisiopatologia , Laringoscopia , Idoso , Adulto Jovem , AdolescenteRESUMO
OBJECTIVE: Injury of the external branch of the superior laryngeal nerve (EBSLN) is easily overlooked in thyroidectomy, and voice changes caused by the injury have a negative effect on an increasing number of patients. This study aimed to reduce the injury rate of EBSLN by expanding the sternothyroid-laryngeal triangle and standardizing the exploration procedure. METHODS: A total of 520 patients who had undergone thyroidectomy at the First Affiliated Hospital of Nanchang University between September 2021 and April 2022 were analyzed. During the operation, the exposure rate of the EBSLN before and after sternothyroid-laryngeal triangle expansion was compared, and all EBSLNs were anatomically classified. RESULTS: The exposure rate of EBSLN after sternothyroid-laryngeal triangle expansion reached 82.7%, which is much higher than that before sternothyroid-laryngeal triangle expansion (33.7%), and voice change caused by injury of the EBSLN was reported in one case (the injury rate was 0.2%). The classification and proportion of the EBSLN were as follows: Type 1 (55.3%), the nerve ran within 1 cm above the STP, but no coincidence or crossover with blood vessels was observed in this region; Type 2 (14.7%), the nerve travelled within 1 cm above the STP and overlapped or intersected with blood vessels in this region; Type 3 (12.7%), the EBSLN ran below the level of the STP; and Type 4 (17.3%), no EBSLN was observed within 1 cm above the STP. CONCLUSION: In thyroidectomy, injury to the EBSLN can be effectively reduced by expanding the sternothyroid-laryngeal triangle and exploring the upper pole area of the thyroid as far as possible, which has great clinical significance in reducing postoperative voice box injury.
Assuntos
Monitorização Intraoperatória , Tireoidectomia , Humanos , Tireoidectomia/efeitos adversos , Tireoidectomia/métodos , Monitorização Intraoperatória/métodos , Glândula Tireoide/cirurgia , Nervos Laríngeos , Músculos Laríngeos/inervaçãoRESUMO
INTRODUCTION: Patients with bilateral vocal fold paralysis (BVFP) experience airway obstruction because of loss of abductor function of posterior cricoarytenoid (PCA) muscles. We previously reported that implantation of autologous muscle progenitor (stem) cells into thyroarytenoid muscles during reinnervation resulted in improved adductor function. In this study, that same approach was applied to treating PCA muscles in a canine model of BVFP. DESIGN: Animal study. METHODS: Two canines underwent baseline measures of glottal resistance (GR), then complete transection and suture repair of both recurrent laryngeal nerves. Muscle stem cells were isolated from skeletal muscle and cultured. Two months later, GR was measured, and then 107 stem cells were implanted into one PCA muscle of each animal. After four more months, GR and glottal opening force (GOF) were measured and the muscles were harvested for histologic study. One control dog underwent the same procedures without stem cell implantation, for comparison. RESULTS: GR increased by 21%-25% over baseline at 2 months, but after stem cell implantation, improved to 10%-14% over baseline at 6 months. PCA muscle strength, as determined by GOF, was 61%-65% on control sides (no stem cells), and 78%-83% on treated sides (with stem cells). Histology confirmed survival of stem cells and a 50% higher rate of innervation of motor endplates in the stem cell treated sides. CONCLUSION: Autologous muscle progenitor (stem) cells show promise as a potential new therapy for patients with bilateral vocal fold paralysis. Additional studies are needed to determine the optimal number of cells, timing of implantation, and other variables before launching a clinical trial. LEVEL OF EVIDENCE: NA (animal study) Laryngoscope, 134:324-328, 2024.
Assuntos
Paralisia das Pregas Vocais , Prega Vocal , Animais , Cães , Eletromiografia , Músculos Laríngeos/inervação , Músculos , Nervo Laríngeo Recorrente/cirurgia , Células-Tronco , Paralisia das Pregas Vocais/cirurgia , Prega Vocal/cirurgiaRESUMO
OBJECTIVE: The superior laryngeal nerve (SLN) is fundamental in laryngeal sensation, cough reflex, and pitch control. SLN injury has substantial consequences including altered sensation, aspiration, and dysphonia. To date, in vivo measurement of the SLN remains elusive. The purpose of this study was to assess the feasibility of recording motor and sensory evoked potentials in a rat SLN model. METHODS: Twenty-two rat hemi-laryngeal preparations (n = 11) were obtained from 4-month-old Sprague-Dawley rats and included in this study. Compound motor action potentials (CMAPs) and motor unit number estimation (MUNE) were calculated by stimulating the SLN at the point of medial extension near the carotid artery and by placing a recording electrode on the cricothyroid muscle. Sensory response was determined through stimulation of the SLN and laryngoscopic visualization of a laryngeal adductor reflex (LAR). SLN and cricothyroid muscle cross-sections were stained and histologic morphometrics were quantified. RESULTS: Laryngeal evoked potentials were successfully obtained in all trials. Mean CMAP latency and negative durations were 0.99 ± 0.57 ms and 1.49 ± 0.57 ms, respectively. The median MUNE was 2.06 (IQR 1.88, 3.51). LAR was induced with a mean intensity of 0.69 ± 0.20 mV. Mean axon count, myelin thickness, and g-ratio were 681 ± 192.2, 1.72 ± 0.26, and 0.45 ± 0.04, respectively. CONCLUSIONS: This study demonstrates the feasibility of recording evoked response potentials following SLN stimulation. We hypothesize that this work will provide a tractable animal model to study changes in laryngeal sensation and cricothyroid motor function with aging, neurodegenerative disease, aspiration, or nerve injury. LEVEL OF EVIDENCE: NA Laryngoscope, 134:1778-1784, 2024.
Assuntos
Doenças Neurodegenerativas , Ratos , Animais , Ratos Sprague-Dawley , Nervos Laríngeos/fisiologia , Músculos Laríngeos/inervação , Reflexo/fisiologiaRESUMO
OBJECTIVES: No curative injectable therapy exists for unilateral vocal fold paralysis. Herein, we explore the early implications of muscle-derived motor-endplate expressing cells (MEEs) for injectable vocal fold medialization after recurrent laryngeal nerve (RLN) injury. METHODS: Yucatan minipigs underwent right RLN transection (without repair) and muscle biopsies. Autologous muscle progenitor cells were isolated, cultured, differentiated, and induced to form MEEs. Three weeks after the injury, MEEs or saline were injected into the paralyzed right vocal fold. Outcomes including evoked laryngeal electromyography (LEMG), laryngeal adductor pressure, and acoustic vocalization data were analyzed up to 7 weeks post-injury. Harvested porcine larynges were examined for volume, gene expression, and histology. RESULTS: MEE injections were tolerated well, with all pigs demonstrating continued weight gain. Blinded analysis of videolaryngoscopy post-injection revealed infraglottic fullness, and no inflammatory changes. Four weeks after injection, LEMG revealed on average higher right distal RLN activity retention in MEE pigs. MEE-injected pigs on average had vocalization durations, frequencies, and intensities higher than saline pigs. Post-mortem, the MEE-injected larynges revealed statistically greater volume on quantitative 3D ultrasound, and statistically increased expression of neurotrophic factors (BDNF, NGF, NTF3, NTF4, NTN1) on quantitative PCR. CONCLUSIONS: Minimally invasive MEE injection appears to establish an early molecular and microenvironmental framework to encourage innate RLN regeneration. Longer follow-up is needed to determine if early findings will translate into functional contraction. LEVEL OF EVIDENCE: NA Laryngoscope, 134:272-282, 2024.
Assuntos
Laringe , Traumatismos do Nervo Laríngeo Recorrente , Paralisia das Pregas Vocais , Animais , Suínos , Prega Vocal , Porco Miniatura , Paralisia das Pregas Vocais/terapia , Eletromiografia , Nervo Laríngeo Recorrente/cirurgia , Células Musculares , Músculos Laríngeos/inervaçãoRESUMO
OBJECTIVES: The aim of the study was to increase muscle volume and improve phonation characteristics of the aged ovine larynx by functional electrical stimulation (FES) using a minimally invasive surgical procedure. METHODS: Stimulation electrodes were placed bilaterally near the terminal adduction branch of the recurrent laryngeal nerves (RLN). The electrodes were connected to battery powered pulse generators implanted subcutaneously at the neck region. Training patterns were programmed by an external programmer using a bidirectional radio frequency link. Training sessions were repeated automatically by the implant every other day for 1 week followed by every day for 8 weeks in the awake animal. Another group of animals were used as sham, with electrodes positioned but not connected to an implant. Outcome parameters included gene expression analysis, histological assessment of muscle fiber size, functional analysis, and volumetric measurements based on three-dimensional reconstructions of the entire thyroarytenoid muscle (TAM). RESULTS: Increase in minimal muscle fiber diameter and an improvement in vocal efficiency were observed following FES, compared with sham animals. CONCLUSION: This is the first study to demonstrate beneficial effects in the TAM of FES at molecular, histological, and functional levels. FES of the terminal branches of the RLN reversed the effects of age-related changes and improved vocal efficiency. LEVEL OF EVIDENCE: NA Laryngoscope, 134:848-854, 2024.
Assuntos
Terapia por Estimulação Elétrica , Paralisia das Pregas Vocais , Ovinos , Animais , Modelos Animais de Doenças , Músculos Laríngeos/inervação , Terapia por Estimulação Elétrica/métodos , Estimulação Elétrica/métodosRESUMO
OBJECTIVE: Muscle RING-finger protein-1 (MuRF-1), an E3 ubiquitin ligase, has been reported to aggravate skeletal muscle denervated atrophy by mediating the ubiquitination degradation of multiple proteins, whereas the molecular mechanism underlying MuRF-1-mediated internal laryngeal muscle denervated atrophy remains unknown. METHODS: A rat unilateral recurrent laryngeal nerve (RLN) transection model was established to evaluate denervated muscle atrophy of the larynx. The expression of MuRF-1, G- and F-actin in thyroarytenoid muscle (TA) myocytes before and after RLN injury was analyzed by immunofluorescence and Western blotting. Coimmunoprecipitation experiments detected molecular interactions between MuRF-1 and G-actin. Immunoprecipitation tested MuRF-1-mediated ubiquitination of G-actin in denervated and innervated TA muscle tissues. The shRNA-MuRF-1 AAV was used to suppress MuRF-1 expression in denervated TA muscles in vivo. RESULTS: First, MuRF-1 expression was significantly elevated in denervated TA muscle compared to innervated TA muscle (p < 0.001). Second, there was a progressive increase in the G/F-actin ratio in TA myocytes from day 3 to 14 after RLNI (p < 0.01). Furthermore, colocalization of MuRF-1 and G-actin in denervated TA myocytes was observed. Moreover, the upregulation of MuRF-1 was closely associated with the ubiquitination of G-actin in denervated TA myocytes and muscle tissues. Knockdown of MuRF-1 decelerated the degree of TA muscle atrophy compared with that in the Blank and NC groups (p < 0.001) but seemed to promote the compensatory movement of the healthy side. CONCLUSION: Collectively, we illustrate a novel molecular mechanism underlying MuRF-1-mediated internal laryngeal muscle denervated atrophy in that MuRF-1 could promote disequilibrium of the G/F-actin ratio by regulating G-actin ubiquitination. LEVEL OF EVIDENCE: NA Laryngoscope, 134:855-864, 2024.
Assuntos
Actinas , Denervação Muscular , Animais , Ratos , Actinas/metabolismo , Denervação , Músculos Laríngeos/inervação , Músculo Esquelético/metabolismo , Atrofia Muscular , UbiquitinaçãoRESUMO
Background: In thyroid surgery, both the recurrent laryngeal nerve (RLN) and external branch of the superior laryngeal nerve (EBSLN) should be preserved for maintaining the vocal cord functions. We aimed to evaluate whether EMG of the CTM applied after the superior pole dissection provided additional informative data to the IONM via ETT or not, regarding the EBSLN function. Methods: The prospectively collected data of the patients, who have undergone thyroidectomy with the use of IONM for the exploration of both the RLN and EBSLN between October 2016 and March 2017, were evaluated retrospectively. Patients over 18 years of age with primary thyroid surgery for malignant or benign thyroid disease, and whom were applied CTM EMG with a needle electrode after the completion of thyroidectomy were included in the study. In the study, each neck side was evaluated as a separate entity considering the EBSLN at risk. Results: The data of 41 patients (32 female, 9 male) (mean age, 46.7 + 9.1; range, 22-71) were evaluated. Sixty seven EBSLNs out of 26 bilateral and 15 unilateral interventions were evaluated. With EBSLN stimulation after the superior pole dissection, positive glottic EMG waveforms via ETT were obtained in 45 (67.2%) out of 67, and the mean glottic amplitude value was 261 + 191 µV (min-max: 116-1086 µV). Positive EMG responses via the CTM EMG were achieved from all of the 67 EBSLNs (100%) with stimulation using a monopolar probe at the most cranial portion above the area of divided superior pole vessels. The mean value of CTM amplitudes via CTM EMG obtained with EBSLN stimulation was 5268 + 3916 µV (min-max:1215 -19726 µV). With EBSLN stimulation, the mean CTM EMG amplitude was detected significantly higher than the mean vocal cord amplitude (p<0.0001). The CTM EMG provided more objective quantifiable data regarding the EBSLN function (100% vs 67,2%, p<0.001). Conclusion: In addition to the IONM via ETT, intraoperative post-dissection CTM EMG via needle electrode is a safe, simple and applicable method that may provide significant additional informative data to IONM with ETT by obtaining and recording objective quantitative data related to the EBSLN function.
Assuntos
Músculos Laríngeos , Tireoidectomia , Humanos , Masculino , Feminino , Adolescente , Adulto , Pessoa de Meia-Idade , Tireoidectomia/métodos , Eletromiografia/métodos , Estudos Retrospectivos , Músculos Laríngeos/inervação , Músculos Laríngeos/cirurgia , Monitorização Intraoperatória/métodos , Nervos Laríngeos/fisiologiaRESUMO
INTRODUCTION/AIMS: Disease or injury can cause neuromuscular changes to the larynx that can affect voice, breathing, and swallowing. Motor nerve conduction studies have had limited use in the study of laryngeal neurophysiology, despite their importance in other anatomic sites. The aim of this study was to explore the feasibility of performing recurrent laryngeal motor nerve conduction studies (rlMNCS) in a rat model. METHODS: rlMNCS were performed in 15 rats under anesthesia. A bipolar stimulating electrode was placed on the recurrent laryngeal nerve (RLN) 5 mm below the cricoid cartilage. Via direct laryngoscopy, a recording electrode was placed transorally into the thyroarytenoid muscle. The RLN was maximally stimulated to determine the compound muscle action potential (CMAP). Three consecutive trials were averaged. RESULTS: The mean stimulating threshold to the RLN to achieve a CMAP from the thyroarytenoid was 1.7 ± 0.6 mA. RLN stimulation caused a visible adductor twitch of the vocal fold in all animals. The mean negative amplitude was 2.0 ± 0.8 mV, and the total area was 1.0 ± 0.4 mV ms. The CMAP latency and negative duration were 1.0 ± 0.1 ms and 0.9 ± 0.2 ms, respectively. DISCUSSION: rlMNCS are feasible and may be useful in understanding laryngeal neurophysiology with disease or injury. This work could provide a tractable animal model for studying and monitoring treatment of neuromuscular conditions affecting voice, breathing, and swallowing.
Assuntos
Estudos de Condução Nervosa , Traumatismos do Nervo Laríngeo Recorrente , Ratos , Animais , Músculos Laríngeos/inervação , Prega Vocal , Nervo Laríngeo Recorrente , EletromiografiaRESUMO
OBJECTIVES: Recurrent laryngeal nerve (RLN) injury results in synkinetic reinnervation and vocal fold paralysis. Investigation of cues expressed in the developing brainstem that influence correct selective targeting of intrinsic laryngeal muscles may elucidate post-injury abnormalities contributing to non-functional reinnervation. Primary targets of interest were Hoxb1 and Hoxb2, members of the Hox family that create overlapping gradients in the developing brain, and their target Phox2b, a transcription factor necessary for cranial nerve branchio- and visceromotoneuron survival. METHODS: Rat embryos at developmental days E14, E16, E18, and E20 (4 animals/age) were sectioned for RNA in situ hybridization to detect Hoxb1, Hoxb2, and Phox2b mRNA within the brainstem. Slides were costained with Islet1 antibody for identification of the nucleus ambiguus. Results were confirmed using immunohistochemistry. Sections were imaged on a confocal microscope. RNA and protein expressions were quantified using QuPath. Statistical analyses were performed using R. RESULTS: Hoxb1, Hoxb2, and Phox2b expressions varied according to embryologic age. Hoxb1 and Hoxb2 expression peaked at E16, with significant decreases at E18 and E20 (one-way ANOVA p = 0.001 for both). Phox2b expression was highest at E14 and trended downward with increased embryologic age (one-way ANOVA p = 0.005). CONCLUSION: Peak expression of Hoxb1 and Hoxb2 is observed at time points when the RLN arrives at the larynx and begins to branch toward individual muscles, positioning these gene products to be involved in cueing laryngeal motoneuron identity and target identification. Higher expression of Phox2b earlier in development suggests a role in laryngeal motoneuron formation. LEVEL OF EVIDENCE: NA Laryngoscope, 133:3462-3471, 2023.
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Genes Homeobox , Traumatismos do Nervo Laríngeo Recorrente , Ratos , Animais , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Bulbo , Músculos Laríngeos/inervação , RNA , Nervo Laríngeo RecorrenteRESUMO
BACKGROUND: Little is known about potential differences in the left recurrent laryngeal nerve (Lrln) and left cricoarytenoideus dorsalis (LCAD) muscle between domestic and feral horse populations. If a difference exists, feral horses may provide a useful control population for research related to recurrent laryngeal neuropathy (RLN) and increase our understanding of potential population pressures influencing the incidence RLN. OBJECTIVES: The objective of this study was to compare the Lrln and LCAD of domestic and feral horses using histological and immunohistochemical techniques (IHC). METHODS: Sixteen horses, domestic (n = 8) and feral (n = 8), without clinical or ancillary examinations that were processed at an abattoir had the Lrln and LCAD muscle harvested immediately following death. Carcass weights were recorded. Subjective and morphometric histologic assessment were performed on Lrln sections. The LCAD was assessed for myosin heavy chain (fibre type proportion, diameter and grouping using IHC. RESULTS: Fibre-type grouping consistent with RLN was seen in both groups. Regenerating fibre clusters were more common in domestic compared to feral horses (p = 0.04). No other histologic differences occurred between groups. Muscle fibre typing demonstrated a lower mean percentage of type IIX fibres in the feral group compared to the domestic group (p = 0.03). There was no difference in type I or IIA proportions or mean diameter of any fibre type between the groups. CONCLUSIONS: The domestic population showed evidence of nerve regeneration suggesting RLN in this group, yet this was not supported by the higher proportion of type IIX muscle fibres compared to the feral population. Further evaluation to clarify the significance and wider occurrence of the differences is indicated.
Assuntos
Doenças dos Cavalos , Cavalos , Animais , Projetos Piloto , Doenças dos Cavalos/epidemiologia , Doenças dos Cavalos/patologia , Músculos Laríngeos/inervação , Músculos Laríngeos/patologia , Músculos , AustráliaRESUMO
PURPOSE: Laryngeal sensory neuropathy (LSN) is caused by a disorder of the superior laryngeal nerve or the recurrent laryngeal nerve. A diagnosis of LSN should include laryngeal electromyography (LEMG) and laryngovideostroboscopy (LVS). The aim of this study was to characterize the physical and subjective symptoms of neuropathy in patients diagnosed with LSN following COVID-19. MATERIAL AND METHODS: Since the beginning of the COVID-19 pandemic, 6 patients who had recovered from the disease presented to us with LSN symptoms. All patients underwent laryngological and phoniatric examination, objective and subjective voice assessment, and LEMG. RESULTS: The most common LSN symptom reported by patients was periodic hoarseness of varying severity. Other common symptoms were the sensation of a foreign body in the throat and voice fatigue. Endoscopy often showed functional abnormalities. The LSN patients could be characterized by LEMG recordings, and all showed abnormal activity of the cricothyroid (CT) muscle. The degree of EMG changes in the CT correlated moderately with the severity of dysphonia. CONCLUSIONS: Sensory neuropathy of the larynx may be a long-lasting complication of SARS-COV-2 infection. The severity of EMG neuropathic changes in the CT muscle broadly corresponds to the severity of dysphonia.
Assuntos
COVID-19 , Disfonia , Doenças do Sistema Nervoso Periférico , Humanos , Eletromiografia , Disfonia/diagnóstico , Disfonia/etiologia , Pandemias , COVID-19/complicações , SARS-CoV-2 , Músculos Laríngeos/inervaçãoRESUMO
OBJECTIVE: The objective of this study is to describe an in vivo rabbit phonation model for glottic insufficiency that is simple and reproducible by means of unilateral transcricothyroid laryngeal muscle stimulation and high-speed video recordings of evoked phonation. STUDY DESIGN: Nonrandomized controlled animal trial. SETTING: Academic medical center. METHODS: A single operation including evoked phonation with bilateral and unilateral transcricothyroid laryngeal muscle stimulation conditions was modeled using 6 New Zealand white rabbits. The effect of stimulation method on glottic cycle, pitch, and loudness was compared. Endoscopic recordings using 5000 frames-per-second image capture technology and audiologic recordings were obtained for all phonation conditions. Primary outcome measures included means of maximum glottal area (MGA)/length pixel ratio, right and left amplitude/length pixel ratios, calculated cycle frequency, auditory recorded frequency, and maximum auditory intensity. Measurements were obtained via pixel counts using ImageJ. RESULTS: Mean MGA/length was significantly greater with unilateral, 20.30, vs bilateral, 9.62, stimulation (P = .043). Mean frequency of 479.92 Hz vs 683.46 Hz (P = .027) and mean maximum intensity of 76.3 dB vs 83.5 dB (P = .013) were significantly increased from unilateral to bilateral stimulation. There was no significant difference in mean right amplitude/length between unilateral and bilateral. CONCLUSION: The described model demonstrates a simple and reproducible means of producing glottic insufficiency due to unilateral vocal fold bowing and represents a pathway for better understanding the biomechanics and pathophysiology of glottic insufficiency due to superior laryngeal nerve injury and vocal fold immobility and offers the potential to compare treatment modalities through in vivo study.
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Disfonia , Glote , Animais , Coelhos , Glote/cirurgia , Músculos Laríngeos/inervação , Fonação/fisiologia , Prega Vocal/cirurgiaRESUMO
BACKGROUND: Selective laryngeal reinnervation using the first and second cervical nerve (C1C2) is a treatment option for recurrent laryngeal neuropathy that aims to restore the function of the cricoarytenoideus dorsalis (CAD) muscle. Despite the technique's satisfying success rate, it has several limitations. These triggered the search for another potential donor nerve that could reduce CAD muscle fatigue and shorten rehabilitation. The ventral branch of the spinal accessory nerve, providing motor innervation to the sternomandibularis (SM) muscle, was identified as a potentially well-adapted nerve. OBJECTIVES: To gather normative data from SM muscle activity induced by physiological spinal accessory nerve stimulation at rest and during exercise, and to determine SM muscle activity and fibre type recruitment relative to posture, gait and respiratory cycle. STUDY DESIGN: Clinical observational study. METHODS: Surface electromyography (EMG) of the SM muscle was performed in nine horses: trained warmbloods, Thoroughbreds and Standardbreds. Signals were recorded in different feeding postures and at exercise, which included standardised treadmill exercise tests, lungeing and ridden work. RESULTS: Timing of the SM muscle contraction coincided with inspiration at gallop. Intra-individual mean SM muscle activity increased with exercising speed (four times higher in Thoroughbreds at gallop than walk and seven times higher in Standardbreds at high-speed trot than walk). Moreover, the SM muscle was strongly activated at rest when the horse was grazing (seven times more than when it was eating out of a hay net or stable feeder). Frequency domain analysis revealed a predominant type I muscle fibre recruitment during feeding and at exercise (type I muscle fibre activity was at least 2.5 times higher than type II muscle fibre activity). MAIN LIMITATIONS: Lack of reference data on equine EMG. CONCLUSIONS: This study confirmed the potentially advantageous properties of the spinal accessory nerve for laryngeal reinnervation.
Assuntos
Nervo Acessório , Músculos Laríngeos , Animais , Cavalos , Músculos Laríngeos/inervação , Músculos , Eletromiografia/veterinária , MarchaRESUMO
The spinal accessory nerve innervates the sternocleidomastoid and trapezius muscles, but the internal branch from the spinal accessory nerve is also contributing to the motor innervation of the larynx. For the first time, we report a case of an impairment of sternocleidomastoid, trapezius, and thyroarytenoid muscles from the same side. In our case, the anatomical variant that can explain this situation implies the cranial roots and some fibers from the spinal roots of the spinal accessory nerve to form the internal branch. In the case of agenesis of these spinal roots, the muscles reliant on it would be missing. For this reason, it is advisable to rule out laryngeal problems in patients with sternocleidomastoid and/or trapezius muscles impairment.
Assuntos
Nervo Acessório , Prega Vocal , Humanos , Nervo Acessório/fisiologia , Músculos do Pescoço , Músculos Laríngeos/inervaçãoRESUMO
PURPOSE: Spasmodic dysphonia (SD) or laryngeal dystonia is as a rare vocal disorder characterized by involuntary action-induced endolaryngeal contraction. In the last decade, botulin toxin injection has become the standard treatment in adductor spasmodic dysphonia necessitating repetitive injections. The purpose of this study is to analyze retrospectively data from patients treated with the minimal-invasive transoral radiofrequency-induced thermotherapy (RFITT) of the terminal branches of the recurrent nerve. METHODS: Between 2009 and 2015, 11 patients (six females and five males aged from 32 to 91 years) with adductor SD were treated with RFITT. Pre-operative and post-operative vocal assessments (VHI-30, GRBASI, and acoustic-aerodynamics measurements), number of surgical revisions, delay between procedures, and post-operative complications were recorded. Statistical analyses were carried out on the first vocal assessment performed 2-8 weeks after the first procedure. RESULTS: Based on available data from ten patients, voice handicap index (VHI) showed improvement with a mean value of -17.7 points (p-value (pval) = 0.014, adjusted p-value (adj pval) = 0.21); instability has also revealed improvement in six patients (pval = 0.05, adj pval = 0.31). Four patients underwent only one procedure including one patient showing still long-term beneficial results after 5 years of follow-up. Other patients required one to three new procedures with an average time between procedures of 15.3 months. Over 24 surgeries performed on a total of 11 patients, one definitive treatment-related severe adverse event was reported. CONCLUSION: Thanks to long-lasting effect, repetitive treatments are less frequent compared to botulin toxin therapy. In our opinion, RFITT is a promising alternative to botulin toxin as a second-step procedure in case of toxin resistance or patient's lack of compliance.
Assuntos
Toxinas Botulínicas , Disfonia , Voz , Adulto , Idoso , Idoso de 80 Anos ou mais , Disfonia/cirurgia , Feminino , Humanos , Músculos Laríngeos/inervação , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Resultado do TratamentoRESUMO
Laminin-111 is a basement membrane protein that participates in motor innervation and reinnervation. During axonal pathfinding, laminin-111 interacts with netrin-1 (NTN1) and changes its attractant growth cone properties into repulsion. While previous models of recurrent laryngeal nerve (RLN) transection show increased Laminin-111 and NTN1 production after injury, developmental expression in the larynx has not been defined. This study investigates the expression of laminin-111 in laryngeal muscles during primary laryngeal innervation of Sprague Dawley rats. Adult larynges and embryos were sectioned for immunohistochemistry with ßIII-Tubulin, laminin subunit α-1 (LAMA1), NTN1, and α-bungarotoxin. Sections were processed for single-molecule inexpensive RNA fluorescence in situ hybridization analysis of LAMA1 mRNA. LAMA1 expression increased in all intrinsic laryngeal muscles, except the medial thyroarytenoid (MTA), at E20.5. At E20.5 there was increased expression in the lateral thyroarytenoid (LTA) and posterior cricoarytenoid (PCA) compared to the MTA. NTN1 upregulation was limited to the LTA and lateral cricoarytenoid (LCA) at E16.5 without any increase in the MTA or PCA. LAMA1 and NTN1 expression did not strictly follow expected patterns relative to the known timing of innervation and does not appear to be acting similarly to its role following RLN injury. These differences between developmental and post-injury innervation provide targets for investigations of therapeutics after nerve injury.
Assuntos
Laminina , Músculos Laríngeos , Traumatismos do Nervo Laríngeo Recorrente , Animais , Ratos , Modelos Animais de Doenças , Hibridização in Situ Fluorescente , Laminina/biossíntese , Laminina/metabolismo , Músculos Laríngeos/crescimento & desenvolvimento , Músculos Laríngeos/inervação , Músculos Laríngeos/metabolismo , Regeneração Nervosa/fisiologia , Netrina-1/metabolismo , Ratos Sprague-Dawley , Traumatismos do Nervo Laríngeo Recorrente/metabolismo , Traumatismos do Nervo Laríngeo Recorrente/patologiaRESUMO
BACKGROUND: Vagus nerve stimulation (VNS) is an adjunctive therapy for drug-resistant epilepsy. Noninvasive evoked potential recordings in laryngeal muscles (LMEPs) innervated by vagal branches may provide a marker to assess effective vagal nerve fiber activation. We investigated VNS-induced LMEPs in patients with epilepsy in acute and chronic settings. MATERIALS AND METHODS: A total of 17 of 25 patients underwent LMEP recordings at initiation of therapy (acute group); 15 of 25 patients after one year of VNS (chronic group); and 7 of 25 patients were tested at both time points (acute + chronic group). VNS-induced LMEPs were recorded following different pulse widths and output currents using six surface laryngeal EMG electrodes to calculate input/output curves and estimate LMEP latency, threshold current for minimal (Ithreshold), half-maximal (I50), and 95% of maximal (I95) response induction and amplitude of maximal response (Vmax). These were compared with the acute + chronic group and between responders and nonresponders in the acute and chronic group. RESULTS: VNS-induced LMEPs were present in all patients. Ithreshold and I95 values ranged from 0.25 to 1.00 mA and from 0.42 to 1.77 mA, respectively. Estimated mean LMEP latencies were 10 ± 0.1 milliseconds. No significant differences between responders and nonresponders were observed. In the acute + chronic group, Ithreshold values remained stable over time. However, at the individual level in this group, Vmax was lower in all patients after one year compared with baseline. CONCLUSIONS: Noninvasive VNS-induced LMEP recording is feasible both at initiation of VNS therapy and after one year. Low output currents (0.25-1.00 mA) may be sufficient to activate vagal Aα-motor fibers. Maximal LMEP amplitudes seemed to decrease after chronic VNS therapy in patients.