Vocal fold electromyography in patients with endoscopic features of unilateral laryngeal paralysis.

<b><br>Introduction:</b> Electromyography (EMG) of the larynx provides information on the electrophysiological condition of laryngeal muscles and innervation. Integration of information obtained from the EMG exams with the clinical parameters as obtained by other methods for laryngeal assessment (endoscopy, perceptual and acoustic analysis, voice self-assessment) provides a multidimensional picture of dysphonia, which is of particular importance in patients with vocal fold (VF) mobility disorders accompanied by glottic insufficiency.</br> <b><br>Aim:</b> The aim of this study was to evaluate laryngeal EMG records acquired in subjects with unilateral vocal fold immobilization with signs of atrophy and glottic insufficiency.</br> <b><br>Material and methods:</b> From the available material of 74 EMG records of patients referred for the exam due to unilateral laryngeal paralysis, records of 17 patients with endoscopic features suggestive of complete laryngeal muscle denervation were selected. The EMG study of thyroarytenoid muscles of mobile and immobile VFs was evaluated qualitatively and quantitatively at rest and during volitional activity involving free phonation of vowel /e/ [ε].</br> <b><br>Results:</b> In all patients, the EMG records from mobile VFs were significantly different from those from immobile VFs. Despite endoscopic features of paralysis, no VF activity whatsoever was observed in as few as 2 patients so as to meet the neurophysiological definition of paralysis. In 88% of cases, electromyographic activity of the thyroarytenoid muscle was observed despite immobilization and atrophy of the vocal fold. In these patients, neurogenic type of record was observed with numerous high- -amplitude mobility units. On the basis of the results, quantitative features of EMG records indicative of paralysis and residual activity of the thyroarytenoid muscle were determined.</br> <b><br>Conclusions:</b> Qualitative and quantitative analysis of laryngeal EMG records provides detailed information on the condition of vocal fold muscles and innervation. EMG records of mobile vs immobile VFs differ significantly from each other. Endoscopic evaluation does not provide sufficient basis for the diagnosis of complete laryngeal muscle denervation.</br>.

Key points for protecting the external branch of the superior laryngeal nerve in open thyroidectomy: A possible exploration technique.

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.

Register transitions in an in vivo canine model as a function of intrinsic laryngeal muscle stimulation, fundamental frequency, and sound pressure level.

Phonatory instabilities and involuntary register transitions can occur during singing. However, little is known regarding the mechanisms which govern such transitions. To investigate this phenomenon, we systematically varied laryngeal muscle activation and airflow in an in vivo canine larynx model during phonation. We calculated voice range profiles showing average nerve activations for all combinations of fundamental frequency (F0) and sound pressure level (SPL). Further, we determined closed-quotient (CQ) and minimum-posterior-area (MPA) based on high-speed video recordings. While different combinations of muscle activation favored different combinations of F0 and SPL, in the investigated larynx there was a consistent region of instability at about 400 Hz which essentially precluded phonation. An explanation for this region may be a larynx specific coupling between sound source and subglottal tract or an effect based purely on larynx morphology. Register transitions crossed this region, with different combinations of cricothyroid and thyroarytenoid muscle (TA) activation stabilizing higher or lower neighboring frequencies. Observed patterns in CQ and MPA dependent on TA activation reproduced patterns found in singers in previous work. Lack of control of TA stimulation may result in phonation instabilities, and enhanced control of TA stimulation may help to avoid involuntary register transitions, especially in the singing voice.

Machine Learning-Assisted Speech Analysis for Early Detection of Parkinson's Disease: A Study on Speaker Diarization and Classification Techniques.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by a range of motor and non-motor symptoms. One of the notable non-motor symptoms of PD is the presence of vocal disorders, attributed to the underlying pathophysiological changes in the neural control of the laryngeal and vocal tract musculature. From this perspective, the integration of machine learning (ML) techniques in the analysis of speech signals has significantly contributed to the detection and diagnosis of PD. Particularly, MEL Frequency Cepstral Coefficients (MFCCs) and Gammatone Frequency Cepstral Coefficients (GTCCs) are both feature extraction techniques commonly used in the field of speech and audio signal processing that could exhibit great potential for vocal disorder identification. This study presents a novel approach to the early detection of PD through ML applied to speech analysis, leveraging both MFCCs and GTCCs. The recordings contained in the Mobile Device Voice Recordings at King's College London (MDVR-KCL) dataset were used. These recordings were collected from healthy individuals and PD patients while they read a passage and during a spontaneous conversation on the phone. Particularly, the speech data regarding the spontaneous dialogue task were processed through speaker diarization, a technique that partitions an audio stream into homogeneous segments according to speaker identity. The ML applied to MFCCS and GTCCs allowed us to classify PD patients with a test accuracy of 92.3%. This research further demonstrates the potential to employ mobile phones as a non-invasive, cost-effective tool for the early detection of PD, significantly improving patient prognosis and quality of life.

Twin vocal folds as a novel evolutionary adaptation for vocal communications in lemurs.

Primates have varied vocal repertoires to communicate with conspecifics and sometimes other species. The larynx has a central role in vocal source generation, where a pair of vocal folds vibrates to modify the air flow. Here, we show that Madagascan lemurs have a unique additional pair of folds in the vestibular region, parallel to the vocal folds. The additional fold has a rigid body of a vocal muscle branch and it is covered by a stratified squamous epithelium, equal to those of the vocal fold. Such anatomical features support the hypothesis that it also vibrates in a manner like the vibrations that occur in the vocal folds. To examine the acoustic function of the two pairs of folds, we made a silicone compound model to demonstrate that they can simultaneously vibrate to lower the fundamental frequency and increase vocal efficiency. Similar acoustic effects are achieved using different features of the larynx for the other primates, e.g., by vibrating multiple sets of ventricular folds in several species and further by an evolutionary modification of enlarged larynx in howler monkeys. Our multidisciplinary approaches found that these functions were acquired through a unique evolutionary adaptation of the twin vocal folds in Madagascan lemurs.

Virtual reality cricothyrotomy - a case-control study on gamification in emergency education.

BACKGROUND: Cricothyrotomy is an invasive and rare emergency intervention to secure the airway in a "cannot intubate, cannot ventilate" situation. This leads to lack of routine. Cricothyrotomy is performed only hesitantly. Therefore, we aim to improve teaching by including a virtual reality (VR) cricothyrotomy as a learning tool. METHODS: We programmed the VR cricothyrotomy in the C# programming language on the open-source Unity platform. We could include 149 students that we randomly assigned to either a study group (VR cricothyrotomy) or control group (educational video). We asked the study group to subjectively rate the VR cricothyrotomy. To evaluate our intervention (VR cricothyrotomy) we took the time participants needed to perform a cricothyrotomy on a plastic model of a trachea and evaluated the correct procedural steps. RESULTS: The majority of students that performed the VR simulation agreed that they improved in speed (81%) and procedural steps (92%). All participants completed the cricothyrotomy in 47s ± 16s and reached a total score of 8.7 ± 0.7 of 9 possible points. We saw no significant difference in time needed to perform a cricothyrotomy between study and control group (p > 0.05). However, the total score of correct procedural steps was significantly higher in the study group than in the control group (p < 0.05). CONCLUSIONS: Virtual reality is an innovative learning tool to improve teaching of emergency procedures. The VR cricothyrotomy subjectively and objectively improved correct procedural steps. Digitized education fills an educational gap between pure haptic experience and theoretical knowledge. This is of great value when focusing on extension of factual knowledge. TRIAL REGISTRATION: DRKS00031736, registered on the 20th April 2023.

Changes in vocal fold gene expression and histology after injection augmentation in a recurrent laryngeal nerve injury model.

OBJECTIVE: To investigate changes in neuroregenerative pathways with vocal fold denervation in response to vocal fold augmentation. METHODS: Eighteen Yorkshire crossbreed swine underwent left recurrent laryngeal nerve transection, followed by observation or augmentation with carboxymethylcellulose or calcium hydroxyapatite at two weeks. Polymerase chain reaction expression of genes regulating muscle growth (MyoD1, MyoG and FoxO1) and atrophy (FBXO32) were analysed at 4 and 12 weeks post-injection. Thyroarytenoid neuromuscular junction density was quantified using immunohistochemistry. RESULTS: Denervated vocal folds demonstrated reduced expression of MyoD1, MyoG, FoxO1 and FBXO32, but overexpression after augmentation. Healthy vocal folds showed increased early and late MyoD1, MyoG, FoxO1 and FBXO32 expression in all animals. Neuromuscular junction density had a slower decline in augmented compared to untreated denervated vocal folds, and was significantly reduced in healthy vocal folds contralateral to augmentation. CONCLUSION: Injection augmentation may slow neuromuscular degeneration pathways in denervated vocal folds and reduce compensatory remodelling in contralateral healthy vocal folds.

Training for Awake, Office-Based Laryngeal Procedures-The Laryngology Fellow's Perspective.

OBJECTIVE: The aim was to explore recent laryngology graduates' perspectives on their experience, competency, and challenges learning office-based procedures during fellowship training in the United States and Canada. METHODS: Anonymous 22-item questionnaire survey was distributed electronically to fellowship-trained laryngologists having completed fellowship within past 5 years. RESULTS: Ninety fellowship-trained laryngologists between 2018 and 2022 were surveyed. Response rate was 48.9% (n = 44), 1 declined participation, with 20 different fellowship programs represented. Fellows were frequently provided the opportunity to act as primary surgeon for most procedures, except for laryngeal botulinum toxin injection, diagnostic laryngeal electromyography, trans-nasal esophagoscopy, secondary tracheoesophageal puncture, and high-resolution pharyngeal manometry. A majority reported high (n = 27, 62.8%) or moderate (n = 12, 27.9%) confidence with vocal fold injection augmentation. Various techniques were taught: transoral (74.4%), cricothyroid (74.4%), thyrohyoid (69.8%), transcartilagenous (14.0%), and catheter-needle (25.6%). Numerous statistically significant associations with independent procedure involvement and competence were identified. Laryngeal botulinum toxin injection was a procedure performed with high frequency but low volume of independent fellow involvement, and the procedure with which fellows reported wanting more practice learning. Most common training barriers included patient being awake, patient consenting to trainee performing the procedure, and the technical challenge/complexity of the procedure. Teaching methods/tools largely focused on informal debriefing (97.3%) and case by case troubleshooting (81.1%). CONCLUSIONS: Laryngology fellows are well trained with favorable perceived levels of competence for numerous office-based procedures, particularly vocal fold injection augmentation. Procedures for which fellows reported a low level of independent participation trended towards lower perceived competency. LEVEL OF EVIDENCE: 5 Laryngoscope, 134:873-881, 2024.

Technical Challenges for Laryngeal Electromyography.

BACKGROUND/OBJECTIVE: Laryngeal electromyography (LEMG) is a useful diagnostic test in the evaluation of vocal fold paralysis (VFP). This study investigates factors that can make LEMG challenging to perform. METHODS: Patients with subacute unilateral VFP presented for LEMG were prospectively enrolled. Demographic data including BMI, previous neck surgery, and anatomic factors were collected. Patient-reported pain related to the procedure was recorded on a visual analogue scale (VAS). Electromyographer and otolaryngologist recorded a consensus rating of the perceived difficulty in performing the test and confidence in using the results for clinical decision-making. RESULTS: A total of 111 patients (56.8% female) were enrolled between August 2015 and August 2018. The mean age was 55 ± 14 years, and the average body mass index (BMI) was 28.5 ± 6.4. The mean patient-reported VAS score for pain was 35 ± 24. Notably, 31.2% of the tests were considered "very easy," 32.1% were considered "mildly challenging" and 23.9% and 12.8% were considered "moderately challenging" and "extremely challenging," respectively, by the clinicians. Common factors affecting LEMG difficulty included poorly palpable surface anatomy (50.5%) and patient intolerance (15.6%). Clinicians felt confident in 76.1% of the test findings. Bivariate analyses showed that prior neck surgery is associated with elevated VAS (p = 0.02), but clinician-perceived difficulty of performing the test is not associated with elevated VAS scores (p = 0.55). CONCLUSIONS: Majority of LEMG tests are well tolerated by patients. Physicians reported more confidence using LEMG for clinical decision-making when the test was easier to perform. Difficult surface anatomy and patient intolerance affects clinician confidence in integrating the test results with clinical care. LEVEL OF EVIDENCE: 3 Laryngoscope, 134:831-834, 2024.

Enhanced Abductor Function in Bilateral Vocal Fold Paralysis with Muscle Stem Cells.

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.

Bilateral Functional Electrical Stimulation for the Treatment of Presbyphonia in a Sheep Model.

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.

Acute Effects of Systemic Glucocorticoids on the Vocal Folds in a Pre-Clinical Model.

OBJECTIVES/HYPOTHESIS: Systemic glucocorticoids (GC)s are employed to treat various voice disorders. However, GCs have varying pharmacodynamic properties with adverse effects ranging from changes in epithelial integrity, skeletal muscle catabolism, and altered body weight. We sought to characterize the acute temporal effects of systemic dexamethasone and methylprednisolone on vocal fold (VF) epithelial glucocorticoid receptor (GR) nuclear translocation, epithelial tight junction (ZO-1) expression, thyroarytenoid (TA) muscle fiber morphology, and body weight using an established pre-clinical model. We hypothesized dexamethasone and methylprednisolone will elicit changes in VF epithelial GR nuclear translocation, epithelial ZO-1 expression, TA muscle morphology, and body weight compared to placebo-treated controls. METHODS: Forty-five New Zealand white rabbits received intramuscular injections of methylprednisolone (4.5 mg; n = 15), dexamethasone (450 µg; n = 15), or volume matched saline (n = 15) into the iliocostalis/longissimus muscle for 6 consecutive days. Vocal folds from 5 rabbits from each treatment group were harvested at 1-, 3-, or 7 days following the final injection and subjected to immunohistochemistry for ZO-1 and GR as well as TA muscle fiber cross-sectional area (CSA) measures. RESULTS: Dexamethasone increased epithelial GR nuclear translocation and ZO-1 expression 1-day following injections compared to methylprednisolone (P = .024; P = .012). Dexamethasone and methylprednisolone increased TA CSA 1-day following injections (P = .011). Methylprednisolone decreased body weight 7 days following injections compared to controls (P = .004). CONCLUSIONS: Systemic dexamethasone may more efficiently activate GR in the VF epithelium with a lower risk of body weight loss, suggesting a role for more refined approaches to GC selection for laryngeal pathology.

Risk of fibromyalgia in patients with primary muscle tension dysphonia: a possible local manifestation of a musculoskeletal systemic disorder.

OBJECTIVE: To investigate the risk of fibromyalgia in patients with primary muscle tension dysphonia. METHODS: A retrospective review was conducted of patients with primary muscle tension dysphonia, diagnosed based on history of dysphonia with evidence of laryngeal muscle tension on examination. Fibromyalgia was assessed using the Fibromyalgia Rapid Screening Tool ('FiRST'). RESULTS: Fifty patients were enrolled: 25 with primary muscle tension dysphonia (study group) and 25 matched controls. The mean age of the study group was 50.7 ± 15.2 years versus 49.5 ± 18.6 years for the controls, with a male to female ratio of 3:2 for both groups. Fifty-six per cent tested positive for fibromyalgia in the study group versus 4 per cent in the controls (p < 0.001). The mean Voice Handicap Index 10 score in the study group was significantly higher for those who screened positive for fibromyalgia compared to those who screened negative. There was a positive, strong point-biserial correlation between Fibromyalgia Rapid Screening Tool and Voice Handicap Index 10 scores (r = 0.39; p = 0.09). CONCLUSION: These results suggest that fibromyalgia is a significant co-morbid condition in primary muscle tension dysphonia.

Spasmodic Dysphonia Patients' Perception of Pain with Botulinum Toxin Injections.

OBJECTIVES: To evaluate spasmodic dysphonia patients' perception of pain associated with laryngeal botulinum toxin (BTX) injections and to determine factors associated with higher pain scores relative to other included patients. METHODS: Prospective cohort study. Adult patients with adductor spasmodic dysphonia that presented to a tertiary laryngology practice for BTX injections were recruited from March to July 2022. Patients completed the visual analog scale (VAS) pre-procedure to quantify predicted pain. Ten minutes post-procedure they completed VAS and the short form McGill Pain Questionnaire (SF-MPQ). Factors that may affect pain were extracted from charts. Descriptive statistics, univariate, and multivariate analyses were conducted (alpha = 0.05). RESULTS: One hundred and nineteen patients were included (63 ± 14 yo, 26% Male). SF-MPQ reported mild pain (4.12 ± 4.05 out of 45) with a pain intensity of none to mild (0.70 ± 0.89 out of 5). Bilateral injections yielded significantly higher SF-MPQ scores (5.19 ± 4.66) than unilateral injections (3.30 ± 3.30) (p = 0.012). There was a significant VAS reduction from pre 28.9 ± 24.6 mm (out of 10 mm) to post 24.5 ± 22.3 (p < 0.001). On multiple regression analyses, receiving a bilateral injection significantly (p < 0.05) contributed to a model that predicted higher pre-VAS (p = 0.013). Bilateral injections (p < 0.05) and higher VHI-10 (p < 0.05) contributed to a model that predicted higher total SF-MPQ (p = 0.001) and affective SF-MPQ (p = 0.001) scores. Not being a professional voice user (PVU) significantly (p < 0.05) contributed to a model that predicted higher post-VAS (p = 0.008) scores. CONCLUSIONS: BTX injections were well tolerated with low pain scores. Factors associated with higher relative predicted or experienced pain included bilateral versus unilateral injection, PVU status, and higher VHI-10. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:240-246, 2024.

Early Changes in Porcine Larynges Following Injection of Motor-Endplate Expressing Muscle Cells for the Treatment of Unilateral Vocal Fold Paralysis.

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.

MuRF-1 is Involved in Laryngeal Muscle Denervation Atrophy by Regulating G-Actin Ubiquitination.

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.

Comparison of the efficacy and adverse effects of unilateral or bilateral botulinum toxin injections for adductor spasmodic dysphonia: a systematic review and meta-analysis.

PURPOSE: This study aims to aggregate and analyze existing clinical evidence to compare the efficacy and adverse effects of unilateral or bilateral botulinum toxin injections for the treatment of adductor spasmodic dysphonia (ADSD). METHODS: Reports from non-randomized controlled trials and cohort studies pertaining to the efficacy and adverse effects of unilateral and bilateral botulinum toxin injections for ADSD were identified and retrieved from four electronic databases from inception to July 2023. The meta-analysis employed fixed or random effects models to assess pooled relative risks (RR), mean differences (MDs), and standard mean differences (SMDs) with their corresponding 95% confidence intervals (CIs). RESULTS: We included two non-randomized controlled trials and seven cohort studies comprising 854 total patients. Meta-analysis of the included studies showed that bilateral botulinum toxin injections associated with a longer duration of vocal improvement (MD = - 2.89, 95% CI - 3.13 to - 2.65, I2 = 0%, P < 0.00001). However, bilateral botulinum toxin injections associated with an increase in adverse effects, including a longer duration of breathy voice quality (SMD = - 0.51, 95% CI - 0.79 to - 0.22, I2 = 35%, P = 0.0005) and a higher occurrence of swallowing difficulties (RR = 0.46, 95% CI 0.35 to 0.11, I2 = 0%, P < 0.00001). CONCLUSION: Bilateral botulinum toxin injections for ADSD showed a longer duration of vocal improvement, a longer breathy voice duration and a higher dysphagia occurrence and duration than unilateral injections.

Analgesia in Transcutaneous Laryngeal Botulinum Toxin Injections: A Randomized Crossover Trial.

OBJECTIVES: There is an absence of data in the literature regarding methods to improve the patient experience during the performance of awake in-office laryngeal injections. This study sought to evaluate whether the use of local anesthetic or a vibrating instrument decreased overall pain experienced by patients with laryngeal dystonia, frequently referred to as spasmodic dysphonia (SD), undergoing transcervical botulinum toxin injections. METHODS: This was an unblinded, prospective randomized control trial with a crossover design where each patient received transcutaneous transcricothyroid injection of botulinum toxin with alternating use of no anesthesia, local anesthesia (2% lidocaine in 1:100,000 epinephrine), and vibrating instrument in three consecutive laryngeal injections to treat adductor SD. Patients were randomized to the order they received these treatments. Patients measured pain on a 0-10 visual analogue scale (VAS) and selected their preferred technique after receiving all three analgesic modalities. RESULTS: Thirty-two patients completed the study. There was no statistically significant difference in pain between the three analgesic techniques (p = 0.38). The most preferred analgesic technique was the vibrating wand (44% (14/32)). Lidocaine was the second most preferred (37% (12/32)) and 19% (6/32) of patients preferred nothing. When combining the wand and nothing groups, 63% of patients preferred one of these two methods (95% exact CI: 44%-79%). CONCLUSION: There was no statistically significant difference in median pain experienced by patients during laryngeal botulinum toxin injection between these different analgesic modalities. More than half of the patients selected a preference for a technique that did not include lidocaine. This data supports individualization of analgesia during transcutaneous laryngeal injections. LEVEL OF EVIDENCE: 2 Laryngoscope, 134:2277-2281, 2024.

Intraoperative cricothyroid muscle electromyography may contribute to the monitorization of the external branch of the superior laryngeal nerve during thyroidectomy.

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.