Posterior Cricoarytenoid Research Articles

Neurophysiological Assessment in Children with Vocal Fold Paralysis: A Tertiary Center Experience.

The aim of this study is to report on experience acquired during the laryngeal electrophysiological assessment with Co-MEP and L-EMG in pediatric patients with acquired, congenital, and syndromic vocal fold paralysis (VFP), and correlate our findings with patients' characteristics, their comorbidities, and VFP etiology. Pediatric patients with suspected or previously diagnosed unilateral or bilateral VFP underwent electrophysiological records under general anesthesia; corticobulbar motor-evoked potentials (Co-MEPs) and laryngeal electromyography (L-EMG) of thyroarytenoid (TA) and posterior cricoarytenoid (PCA) muscles were recorded. Statistical analysis revealed a statistically significant correlation between early gestational age at childbirth and TA muscle intensity (p = 0.002) and PCA muscle intensity (p = 0.002); tracheostomy presence and TA muscle intensity (p = 0.002) and PCA muscle intensity (p = 0.002); presence of genetic anomalies with intensity and latency for TA muscle and latency for PCA muscle (TA latency p = 0.015, TA intensity p = 0.021, PCA latency p = 0.035); congenital presentation of VFP and an increased intensity for TA muscle (p = 0.04); latency and intensity for TA muscle (p = 0.024); TA muscle intensity and PCA intensity (p = 0.005). Intraoperative Co-MEPs and L-EMG are two complementary tools for evaluating the functional integrity of the structures involved in conveying signals from the motor cortex to TA and PCA muscles in children with vocal fold paralysis. Further studies are needed to establish their ability to predict the recovery of VF mobility, which could potentially lead to decannulation. Level 4 Laryngoscope, 2024.

Impact of functional electrical stimulation on nerve-damaged muscles by quantifying fat infiltration using deep learning.

Quantitative imaging in life sciences has evolved into a powerful approach combining advanced microscopy acquisition and automated analysis of image data. The focus of the present study is on the imaging-based evaluation of the posterior cricoarytenoid muscle (PCA) influenced by long-term functional electrical stimulation (FES), which may assist the inspiration of patients with bilateral vocal fold paresis. To this end, muscle cross-sections of the PCA of sheep were examined by quantitative image analysis. Previous investigations of the muscle fibers and the collagen amount have not revealed signs of atrophy and fibrosis due to FES by a laryngeal pacemaker. It was therefore hypothesized that regardless of the stimulation parameters the fat in the muscle cross-sections would not be significantly altered. We here extending our previous investigations using quantitative imaging of intramuscular fat in cross-sections. In order to perform this analysis both reliably and faster than a qualitative evaluation and time-consuming manual annotation, the selection of the automated method was of crucial importance. To this end, our recently established deep neural network IMFSegNet, which provides more accurate results compared to standard machine learning approaches, was applied to more than 300 H&E stained muscle cross-sections from 22 sheep. It was found that there were no significant differences in the amount of intramuscular fat between the PCA with and without long-term FES, nor were any significant differences found between the low and high duty cycle stimulated groups. This study on a human-like animal model not only confirms the hypothesis that FES with the selected parameters has no negative impact on the PCA, but also demonstrates that objective and automated deep learning-based quantitative imaging is a powerful tool for such a challenging analysis.

Transcriptome Analysis of Left Versus Right Intrinsic Laryngeal Muscles Associated with Innervation.

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. Laboratory experiment. 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. 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. Bioinformatics analysis confirmed divergent transcriptome profiles between the left-right ILMs. This preliminary study identifies putative gene targets that will characterize ILM laterality. N/A Laryngoscope, 134:3741-3753, 2024.

Long-term stimulation by implanted pacemaker enables non-atrophic treatment of bilateral vocal fold paresis in a human-like animal model

A wide variety of treatments have been developed to improve respiratory function and quality of life in patients with bilateral vocal fold paresis (BVFP). One experimental method is the electrical activation of the posterior cricoarytenoid (PCA) muscle with a laryngeal pacemaker (LP) to open the vocal folds. We used an ovine (sheep) model of unilateral VFP to study the long-term effects of functional electrical stimulation on the PCA muscles. The left recurrent laryngeal nerve was cryo-damaged in all animals and an LP was implanted except for the controls. After a reinnervation phase of six months, animals were pooled into groups that received either no treatment, implantation of an LP only, or implantation of an LP and six months of stimulation with different duty cycles. Automated image analysis of fluorescently stained PCA cross-sections was performed to assess relevant muscle characteristics. We observed a fast-to-slow fibre type shift in response to nerve damage and stimulation, but no complete conversion to a slow-twitch-muscle. Fibre size, proportion of hybrid fibres, and intramuscular collagen content were not substantially altered by the stimulation. These results demonstrate that 30 Hz burst stimulation with duty cycles of 40% and 70% did not induce PCA atrophy or fibrosis. Thus, long-term stimulation with an LP is a promising approach for treating BVFP in humans without compromising muscle conditions.

Analysis of vocal fold movement characteristics in patients with laryngeal neurogenic injury

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 group（P<0.05）, the composition of normal and reduced vocal fold motion in bilateral vocal fold paralysis group（47.70%） was significantly greater than that in unilateral vocal fold paralysis group（12.27%）. 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 group（P<0.05）. The proportion of decreased vocal fold motion in superior laryngeal nerve paralysis group（50.00%） was higher than that in recurrent laryngeal nerve paralysis group（9.32%） and vagal nerve paralysis group（9.00%）. 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 significant（P<0.05）.There was no significant difference in glottic closure among the three groups（P<0.05）. 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.

Influence of Microinjection of Kynurenic acid into the Pre-Botzinger Complex on Swallowing in the Cat

Recent evidence supports the involvement of the pre-BÖtzinger complex (pre-BOT) in spatiotemporal features of swallowing and swallowing-breathing coordination in mice. We hypothesized that pharmacological disruption of glutamate neurotransmission in this brainstem region would perturb the swallow motor pattern in anesthetized cats. Electromyograms (EMGs) of upper airway muscles were recorded in anesthetized, spontaneously breathing cats (n=5). Swallowing was induced by injection of 3 cc of water into the oropharynx. Multi-barrel micropipettes were employed to inject artificial cerebrospinal fluid or kynurenic acid (KYN; 50 mM, 44±3 nL per injection) bilaterally into the region of the pre-BOT. Microinjection sites were confirmed histologically by detection of fluorescent beads that were suspended in the microinjectate. Blocking glutamate-related neuronal excitation by bilateral microinjections of the nonspecific glutamate receptor antagonist kynurenic acid had no effect on the number of swallows induced by water injection (control 2.3±0.3; KYN 3.0±0.7; P&lt;0.32). Swallow durations were significantly increased following microinjections of KYN from 691±54 ms to 812±81 ms (p&lt;0.04). KYN significantly reduced the magnitudes of geniohyoid (control 97±3 % of median; Kyn 47±12% of control median, p&lt;0.02), thyrohyoid (control 100±3% of median; KYN 69±8% of control median, p&lt;0.01), and posterior cricoarytenoid (control 103±2% of median; KYN 74±8% of control median, p&lt;0.04) muscle EMGs during swallowing. There was no significant effect of microinjection of KYN on the magnitudes of thyroartytenoid, mylohyoid, or thyropharyngeus electromyograms during swallowing. The results suggest that disruption of glutamate neurotransmission in the preBOT has preferential effects consistent with actions on motor drive to hypoglossal and ventrolateral motoneuron pools that participate in swallowing. Lengthening of swallow duration induced by KYN supports a role for the preBOT in modulating the excitability of the swallow oscillatory circuit. NIH HL163008; NIH HL 131716; HL 155721. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Current opinion on laryngeal electromyography

PurposeThis study evaluates expert opinion on laryngeal electromyography (LEMG). MethodsA cross-sectional design was used to conduct an online survey of LEMG experts in 2021. They were questioned about the number LEMG performed annually, type of electrodes used, sector worked in, pain during the test, placement of the needle electrodes, interpretation of electrical muscle parameters, diagnosis of neuromuscular injury, prognostic sensitivity in vocal fold paralysis (VFP), laryngeal dystonia, tremor and synkinesis and quantifying LEMG. ResultsThirty-seven professionals answered (23 Spanish and 14 from other countries), with a response rate of 21.56%. All physicians used LEMG. 91.9% had one- or two-years’ experience and 56.8% performed 10–40 LEMG per year. 70.3% were otolaryngologists and 27%, neurologists. In 89.1% of cases, a team of electrodiagnostic physician and otolaryngologist performed LEMG. 91.3% of Spanish respondents worked in Public Health, 7.14% of other nationalities; 37.8% in a university department. Bipolar concentric needles electrodes were used by 45.9% and monopolar concentric by 40.5%. 57% professionals considered good patients’ tolerance to the test. LEMG sensitivity was regarded as strong, median and interquartile range were 80.0 [60.0;90.0] to diagnose peripheral nerve injuries, less for other levels of lesions, and strong to evaluate prognosis, 70.0 [50.0;80.0]. Respondents believe locate the thyroarytenoid and the cricothyroid muscles with the needle, 80.0 [70.0;90.0], as opposed to 20.0 [0.00;60.0] the posterior cricoarytenoid. The interpretation of the electrical parts of the LEMG was strong, 80.0 [60.0;90.0]. LEMG identify movements disorders, 60.0 [20.0;80.0], and synkinesis, 70.0 [30.0;80.0]. The professionals prefer quantitative LEMG, 90.0 [60.0;90.0]. ConclusionsThe experts surveyed consider LEMG that is well tolerated by patients. The insertional and spontaneous activity, recruitment and waveform morphology can be assessed easily. LEMG is mainly useful in the study of peripheral nerve injuries, and its value in VFP prognosis is considered strong.

Serotonin therapies for opioid-induced disordered swallow and respiratory depression.

Opioids are well-known to cause respiratory depression, but despite clinical evidence of dysphagia, the effects of opioids on swallow excitability and motor pattern are unknown. We tested the effects of the clinically relevant opioid buprenorphine on pharyngeal swallow and respiratory drive in male and female rats. We also evaluated the utility of 5-HT1A agonists (8-OH-DPAT and buspirone) to improve swallowing and breathing following buprenorphine administration. Experiments were performed on 44 freely breathing Sprague-Dawley rats anesthetized with sodium pentobarbital. Bipolar fine wire electrodes were inserted into the mylohyoid, thyroarytenoid, posterior cricoarytenoid, thyropharyngeus, and diaphragm muscles to measure electromyographic (EMG) activity of swallowing and breathing. We evaluated the hypotheses that swallowing varies by stimulus, opioids depress swallowing and breathing, and that 5-HT1A agonists improve these depressions. Our results largely confirmed the following hypotheses: 1) swallow-related EMG activity was larger during swallows elicited by esophageal distension plus oral water infusion than by either stimulus alone. 2) Buprenorphine depressed swallow in both sexes, but females were more susceptible to total swallow suppression. 3) Female animals were also more vulnerable to opioid-induced respiratory depression. 4) 8-OH-DPAT rescued breathing following buprenorphine-induced respiratory arrest, and pretreatment with the partial 5-HT1A agonist buspirone prevented buprenorphine-induced respiratory arrest in female animals. 5) 8-OH-DPAT enhanced mylohyoid and thyropharyngeus EMG amplitude during swallow but did not restore excitability of the swallow pattern generator following total suppression by buprenorphine. Our results highlight sex-specific and behavior-specific effects of buprenorphine and provide preclinical evidence of a 5HT1A agonist for the treatment of respiratory depression and dysphagia.NEW & NOTEWORTHY This is the first study, to our knowledge, to evaluate sex-specific effects of opioid administration on pharyngeal swallow. We expand on a small but growing number of studies that report a lower threshold for opioid-induced respiratory depression in females compared with males, and we are the first to produce this effect with the partial μ-opioid-receptor agonist buprenorphine. This is the first demonstration, to our knowledge, that activation of 5-HT1A receptors can improve swallow and breathing outcomes following systemic buprenorphine administration.

Vocal Fold Paresis and Voice Outcomes following Vocal Fold Mass Excision.

To correlate the surgical results of vocal fold mass excision with pre-operative existence of vocal fold paresis. Data were collected on 66 patients who underwent excision of benign vocal fold masses from 2015 to 2020. The pre- and post-operative strobovideolaryngoscopy (SVL) examinations for all patients included were evaluated blindly by three otolaryngologists using THE Voice-Vibratory Assessment with Laryngeal Imaging (VALI) Form for scar severity, mucosal wave, free edge contour, glottal closure, and phase closure. The success of mass excision surgery was determined based on the presence of the following criteria post-operatively: 1) improved mucosal wave motion 2) improved phase closure or glottic closure 3) improved free edge contour and 4) lack of worsening of vocal fold scar severity. Surgery was considered successful if 3 or 4 criteria were met, partially successful if 1 or 2 criteria were met, and unsuccessful if no criteria were met. The percent recruitment of the thyroarytenoid, posterior cricoarytenoid (PCA), and cricothyroid muscles were used evaluated the severity of paresis as mild (70-99% recruitment), moderate (40-60% recruitment), or severe (0-39% recruitment). VHI-10 scores were used as subjective measures of pre- and post-operative voice. Sixty-six patients (26 male, 40 female) were included in this study, with a mean age of 37.25 ± 16.6 (range 18-78). Twelve patients had no evidence of VF paresis noted during the initial clinical evaluation; and 52 patients had paresis and had undergone laryngeal EMG. 81% of these patients had mild paresis, 12.8% had moderate paresis, and 5.8% had severe paresis. Based on pre- and post-operative strobovideolaryngoscopy, there was improvement in mucosal wave in 44.9% of cases, improvement of phase or glottic closure in 85.4% of cases, improved free edge contour in 95.5% of cases, and worsening of scar in 38.5% of cases. 39.6% of surgeries were fully successful, 33.3% of surgeries were partially successful, and 27.1% were not successful. There was a significant correlation between female gender and vocal fold paresis (P=0.048). Paresis severity did not correlate with complete or partial surgical success (P=0.956), pre-operative VHI-10 scores (P=0.519), post-operative VHI-10 scores (P=0.563), or strobovideolaryngoscopy parameters. Unilateral and bilateral paresis did not correlate with any other parameter of surgical success (P >0.05). This study suggests that there is no correlation between pre-operative vocal fold paresis and voice outcomes after mass excision surgery, that the majority of mass excision surgeries (72.9%) are successful based on improvement in stroboscopic parameters, and that the proportion of patients with moderate and severe paresis is consistent across all laryngeal nerves.

Use of a rigid curved laryngoscope for observation and debridement of degenerated cricoid cartilage in nasogastric tube syndrome: A case report.

Nasogastric tube syndrome (NGTS) is a complication of NGT placement that can cause sore throat, bilateral vocal cord paralysis, and airway constriction. Although rare, this condition should be known by all physicians because it is sometimes fatal. We report a case of NGTS that was successfully diagnosed and debrided with a rigid curved laryngoscope. A 79-year-old man was referred to our department for evaluation of persistent pharyngeal pain and dysphagia after thoracic aortic aneurysm surgery. He had restricted bilateral vocal fold abduction, and the NGT had been placed for nearly 120 days. After induction of general anesthesia, the patient underwent laryngeal examination using a rigid curved laryngoscope, which revealed ossified cricoid cartilage in the postcricoid area, leading to confirmation of NGTS. The NGT was removed, and the protruding bony lesion was debrided. Subsequently, the patient underwent gastrostomy to improve his nutritional status. One month later, the postcricoid lesion improved, and the patient was able to tolerate an oral diet. The pathophysiology of NGTS is thought to involve ulceration of the postcricoid mucosa and injury of the posterior cricoarytenoid muscle by contact with the NGT. Although the treatment has not been established, early removal of the NGT is important. In the present case, the rigid curved laryngoscope was useful for resection of the bony lesion, which contributed to early epithelialization and symptom improvement.

Current opinion on laryngeal electromyography

PurposeThis study evaluates expert opinion on laryngeal electromyography (LEMG). MethodsA cross-sectional design was used to conduct an online survey of LEMG experts in 2021. They were questioned about the number LEMG performed annually, type of electrodes used, sector worked in, pain during the test, placement of the needle electrodes, interpretation of electrical muscle parameters, diagnosis of neuromuscular injury, prognostic sensitivity in vocal fold paralysis (VFP), laryngeal dystonia, tremor and synkinesis and quantifying LEMG. ResultsThirty-seven professionals answered (23 Spanish and 14 from other countries), with a response rate of 21.56%. All physicians used LEMG. 91.9% had one- or two-years’ experience and 56.8% performed 10–40 LEMG per year. 70.3% were otolaryngologists and 27%, neurologists. In 89.1% of cases, a team of electrodiagnostic physician and otolaryngologist performed LEMG. 91.3% of Spanish respondents worked in Public Health, 7.14% of other nationalities; 37.8% in a university department. Bipolar concentric needles electrodes were used by 45.9% and monopolar concentric by 40.5%. 57% professionals considered good patients’ tolerance to the test. LEMG sensitivity was regarded as strong, median and interquartile range were 80.0 [60.0;90.0] to diagnose peripheral nerve injuries, less for other levels of lesions, and strong to evaluate prognosis, 70.0 [50.0;80.0]. Respondents believe locate the thyroarytenoid and the cricothyroid muscles with the needle, 80.0 [70.0;90.0], as opposed to 20.0 [0.00;60.0] the posterior cricoarytenoid. The interpretation of the electrical parts of the LEMG was strong, 80.0 [60.0;90.0]. LEMG identify movements disorders, 60.0 [20.0;80.0], and synkinesis, 70.0 [30.0;80.0]. The professionals prefer quantitative LEMG, 90.0 [60.0;90.0]. ConclusionsThe experts surveyed consider LEMG that is well tolerated by patients. The insertional and spontaneous activity, recruitment and waveform morphology can be assessed easily. LEMG is mainly useful in the study of peripheral nerve injuries, and its value in VFP prognosis is considered strong.

An Euler–Bernoulli-type beam model of the vocal folds for describing curved and incomplete glottal closure patterns

Incomplete glottal closure is a laryngeal configuration wherein the glottis is not fully obstructed prior to phonation. It has been linked to inefficient voice production and voice disorders. Various incomplete glottal closure patterns can arise and the mechanisms driving them are not well understood. In this work, we introduce an Euler–Bernoulli composite beam vocal fold (VF) model that produces qualitatively similar incomplete glottal closure patterns as those observed in experimental and high-fidelity numerical studies, thus offering insights into the potential underlying physical mechanisms. Refined physiological insights are pursued by incorporating the beam model into a VF posturing model that embeds the five intrinsic laryngeal muscles. Analysis of the combined model shows that co-activating the lateral cricoarytenoid (LCA) and interarytenoid (IA) muscles without activating the thyroarytenoid (TA) muscle results in a bowed (convex) VF geometry with closure at the posterior margin only; this is primarily attributed to the reactive moments at the anterior VF margin. This bowed pattern can also arise during VF compression (due to extrinsic laryngeal muscle activation for example), wherein the internal moment induced passively by the TA muscle tissue is the predominant mechanism. On the other hand, activating the TA muscle without incorporating other adductory muscles results in anterior and mid-membranous glottal closure, a concave VF geometry, and a posterior glottal opening driven by internal moments induced by TA muscle activation. In the case of initial full glottal closure, the posterior cricoarytenoid (PCA) muscle activation cancels the adductory effects of the LCA and IA muscles, resulting in a concave VF geometry and posterior glottal opening. Furthermore, certain maneuvers involving co-activation of all adductory muscles result in an hourglass glottal shape due to a reactive moment at the anterior VF margin and moderate internal moment induced by TA muscle activation. These findings have implications regarding potential laryngeal maneuvers in patients with voice disorders involving imbalances or excessive tension in the laryngeal muscles such as muscle tension dysphonia.

Atrophy of the Posterior Cricoarytenoid Muscle as an Indicator of a Recurrent Laryngeal Nerve Injury History Before Revision Anterior Cervical Spine Surgery.

Retrospective study. In our recent study, we observed some cases of symptomatic normal vocal cord motility instead of asymptomatic vocal cord palsy (VCP) in preoperative laryngoscopy of a revision anterior cervical spine surgery (ACSS) cohort. We assumed the intrinsic muscle atrophy caused by recurrent laryngeal nerve injury could cause vocal cord-related symptoms. Thus, radiological examinations were reviewed in relation to the posterior cricoarytenoid (PCA) muscle, one of the intrinsic muscles. We retrospectively analyzed 64 patients who underwent a revision ACSS. Patients with vocal cord-related symptoms were classified as symptomatic group (group S, n = 11), and those without symptoms as asymptomatic group (group AS, n = 53). The bilateral size and signal intensity of the PCA muscles in these patients were measured in the axial view with preoperative computed tomography (CT) and magnetic resonance imaging (MRI) evaluations. Since the size and signal intensity values were different on each image, the ratios of the contralateral and ipsilateral muscle values were analyzed for each modality. There was no VCP on laryngoscopy study. However, the mean ratio of the PCA muscle size on CT was 1.40 ± .37 in group S and 1.02 ± .12 in group AS (P = .007). These values on the MRI were 1.49 ± .45 in group S and 1.02 ± .14 in group AS, which was also a significant difference (P = .008). Evaluating the size of the PCA muscle before revision ACSS may predict a previous recurrent laryngeal nerve injury. Careful planning for the appropriate approach should be undertaken if vocal cord-related symptoms and atrophy of PCA muscle are evident.

Laryngeal dystonia: Phenomenology, genetics, and management

Laryngeal dystonia is a task-specific movement disorder causing abnormal movement of the adductor or abductor muscles of the vocal folds. In 1984, Blitzer pioneered the first use of onabotulinum toxin A to treat this disorder. Over 1400 patients were diagnosed with laryngeal dystonia in the last thirty years. In this paper, we summarize their clinical and endoscopic findings as well as treatment results. We also summarize the underlying genetics of the disorder.82% of patients were diagnosed with adductor type laryngeal dystonia and 17% of patients manifested an abductor laryngeal dystonia. Patients with adductor dystonia were treated with toxin to the thyroarytenoid muscles and those with abductor dystonia were treated with toxin to the posterior cricoarytenoid muscle. All patient achieved greater than 70% improvement in percent normal function. Laryngeal dystonia is a rare movement disorder of the larynx with an incidence of approximately 35.1 per 100,000 individuals (Simonyan et al., 2021). Presently, there is no cure for laryngeal dystonia, but botulinum toxin has shown significant success in treating the symptoms of the disorder.

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

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. Animal study. 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. 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. 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. NA (animal study) Laryngoscope, 134:324-328, 2024.

Dynamic CT Study on the Morphology and the Motor Ability of Unilateral Vocal Fold Paralysis

To investigate the morphological changes and motor functions of the larynx in unilateral vocal fold paralysis by using dynamic three-dimensional CT, and to explore the differences between vocal fold paralysis with different nerves involved. Twenty-five patients with unilateral vocal fold paralysis and 10 healthy subjects were selected as the paralytic group and the normal group, respectively. Tendynamic sequence images of laryngeal movement from inhalation to phonation were reviewed, and the glottic morphology at the coronal position, the minimum glottic area at the horizontal position, and the overall activity of the two groups were compared. The 25 patients with unilateral vocal fold paralysis were divided into the thyroarytenoid (TA)musclegroup, the TAand posterior cricoarytenoid (PCA) (TA+PCA) musclegroup, and the PCA musclegroup. The coronal and horizontal parameters of the three types were compared as noted above and the dynamic parameter changes were also compared between the groups. The height and thickness of bilateral vocal cords, the minimum glottic area, and the whole glottic activity were different in the paralysis group and were significantly different from those of the normal group (P<0.05). The value of the glottic gap ratio and its decrease rate in the TA+PCA group was smaller than those in the TA and PCA group, and the glottic gap ratio was the largest in the PCA group. Dynamic CT can provide a qualitative evaluation of laryngeal morphology and quantitative evaluation of motor function in vocal fold paralysis.

Motor neuron involvement threatens survival in spinocerebellar ataxia type 1.

Motor neuron involvement threatens survival in spinocerebellar ataxia type 1.

High Tracheal Resection With Intralaryngeal Extension as an Alternative to Cricotracheal Resection for Treatment of Subglottic Stenosis.

Some patients with subglottic stenosis (SGS) require open airway reconstruction, which traditionally involves resection of the anterior cricoid cartilage. As an alternative, we present a novel technique: cricoid-sparing high tracheal resection with excision of subglottic stenotic tissue from below. A novel set of posterior circumferential cricoid sutures is used to reline the exposed cricoid plate. Retrospective chart review. Single tertiary care center. The surgical technique is described and illustrated. A chart review was performed for all patients who underwent surgery between January 1, 2016, and June 30, 2021. Fourteen patients (100% female) underwent this airway resection and reconstruction surgery during the study time period. After a mean follow-up of 12 months, no patients required tracheostomy. Twelve of 14 patients (86%) had durable airways. Two patients (14%) have required repeated endoscopic procedures for recurrent stenosis and are considered treatment failures. None exhibited postoperative dysfunction to suggest posterior cricoarytenoid muscle injury. Thirteen patients (93%) had a postoperative normal voice or only transient dysphonia. One patient had permanent unilateral vocal fold paralysis. Cricoid-sparing high tracheal resection is a safe and effective alternative to cricotracheal resection, especially for predominantly posterior SGS. The cricoid cartilage and cricothyroid muscles are left undisturbed, potentially decreasing the risk of postoperative dysphonia, namely lowered fundamental frequency. This is especially meaningful in the setting of a predominantly female patient population.

Spasmodic Dysphonia

Spasmodic dysphonia (SD) is a chronic voice disorder characterized by excessive or inappropriate contraction of laryngeal muscles during speech. SD manifests as excessive glottic closure (adductor type) or sudden opening of the vocal folds (abductor type). Strained or strangled voice is the main symptom of adductor type SD, while abductor type SD presents with a breathy or absent voice. Adductor type SD accounts for 97% of all SD cases and 70% display abnormal contractions of extra laryngeal muscles. SD is currently understood to be a focal dystonia of inner laryngeal muscle during speech. Injection of botulinum toxin into laryngeal muscles is the primary treatment for SD, similar to other dystonia diseases. As the effects of botulinum toxin last for around three months, patients need repeated injections. There are two kind of surgical procedures which aim to achieve permanent emission, namely type 2 thyroplasty (TP2) and bilateral thyroarytenoid muscle myectomy (TAM). Both of these are effective and over 50% of patients can become symptom-free. However, in some cases, patient voices can become breathy and pitch ranges are reduced. For abductor type SD, there are no effective treatments apart from botulinum toxin injections into posterior cricoarytenoid muscles which open the vocal folds.

NERVE MONITORING IN THYROID SURGERY: A RETROSPECTIVE COHORT STUDY

Background:The proximity of the Recurrent Laryngeal and External Branch of Superior Laryngeal Nerve to the Thyroid Gland has been a key factor for a profound interest of surgeons and clinicians in the clinical outcomes and Vocal changes in the post operative period in the patients undergoing thyroid surgery. The presence of Recurrent Laryngeal nerve in proximity of Thyroid poses a significant risk of damage to the nerve during surgery. The Recurrent Laryngeal Nerve SuppliesLarynx below the level of vocal cords and all the muscles except Cricothyroid. Posterior Cricoarytenoid, the only abductor of vocal cord is also supplied by this nerve. So, any damage to the nerve during surgery causes significant changes in pitch and texture of voice, commonly referred to as hoarseness.Intra-operative Nerve Monitoringwas introduced about 50 years ago and various neuromonitoring methods (glottis pressure method, glottic monitoring method, insertion of needle electrodes invocal cords endoscopically or through cricothyroid membrane, laryngeal palpationmethod, and monitoring via endotracheal tube with surface electrodes) have been utilized. We present a retrospective cohort study to surmise the effect of the use of Intraoperative nerve monitoring devices during Thyroid surgery and compare the clinical outcome in two cohorts. First, the study group where the nerve monitoring was used intraoperatively and the Second, where no intraoperative nerve monitoring was used. All the Patients included in the study underwent Thyroid surgery in the Department of Otorhinolaryngology-Head and Neck Surgery, MBS Hospital, Kota. Methods:This retrospective cohort study includes 100 patients as per the inclusion criteria specified in this article and all the included patients were studied after dividing them into two groups with one group where intraoperative nerve monitoring was used and the other group where no nerve monitoring was used. Each group had 50 patients each. All the patients are regularly documented for with Video Laryngoscopic Examination as a standard. All the data collected from the archives and put to statistical evaluation to analyse the data Age wise, Sex wise, Residential address wise, according to mean Thyroid volume, according to presenting complaints, according to history, according to mean operative time, according to the type of Nerve Injury, according to duration of hospital stay and other parameters as followed in the study. Results: On appropriate statistical analysis of the data, it was seen that there were no demographic variables within groups that ensured statistical similarity in the groups, there was also no statistical correlation of functional preservation attributable to mean Thyroid volume. The incidence of nerve injury was higher in the patients who got themselves operated for the malignancy of thyroid and the revision surgeries. The patients being operated for controlled toxic goitre reported ni nerve injury in the post operative period. The intraoperative nerve monitoring reported lower mean time required to do the surgery. There was a similar incidence of permanent and transient nerve injury in both the cohort groups.