Effects of stretching exercises on muscle tension, fatigue, strength, and lactic acid accumulation: A pre-experimental study among fish transport workers.

Fish transport workers in Indonesia lift loads more than the specified limits, both in weight and frequency. This could cause lactic acid accumulation, fatigue and reduced physical performance. The aim of this study was to assess the effect of stretching intervention on muscle tension, fatigue, strength, and lactic acid level in fish transport workers in Indonesia. A pre-experimental study design with one group (pre- and post-test) design was conducted among male fish transport workers at the Tawang fish auction, Weleri, Central Java, Indonesia, in June 2022 for two weeks. We created a 1.5-minute stretching exercise video based on the University of New Castle's Manual Handling guideline, involving hand, feet, and shoulder movements. Participants performed these exercises independently before and during work every two hours, guided by the video. Data on lactic acid, muscle tension, fatigue, and strength were collected before and after the 2-week intervention. Data analysis was performed using Wilcoxon and paired Student t-tests to compare the outcome between post- and pre-intervention. A total of 18 fish transport workers were included in the study. The results showed a statistically significant increase in lactic acid levels following the intervention (p=0.016). However, the increase in muscle tension was not statistically significant (p=0.292). There was a significant increase in fatigue levels after the intervention (p=0.000). This could suggest that the stretching intervention may have had an unintended effect of increasing fatigue among the participants. On the other hand, there was a statistically significant decrease in muscle strength after the intervention (p=0.003). In conclusion, this study suggests that while stretching exercises can affect lactic acid accumulation, fatigue, and muscle strength, they do not influence muscle tension. Therefore, it is advised for workers to incorporate stretching exercises into their daily routine to mitigate potential injury risks.

Chloroquine and cinchonine affect rat vascular smooth muscle tonus through calcium channels - in silico and in vitro approaches.

BACKGROUND: In the present study, two structurally similar alkaloids from trees of Cinchona genus, chloroquine and cinchonine, were examined for their vasorelaxant effects in a model of phenylephrine-induced smooth muscle contractions. METHODS: Potential mechanisms of action associated with endothelial vasorelaxant compounds, voltage-gated Ca2+ channels (LTCCs), and inositol triphosphate receptors were examined in isolated rat aortic rings. Also, an in silico approach was used to predict the activity of the two test compounds. RESULTS: Experimental results revealed that both chloroquine and cinchonine significantly decrease phenylephrine-induced smooth muscle contractions, although to a different extent. Evaluated mechanisms of action indicate that endothelium is not involved in the vasorelaxant action of the two tested alkaloids. On the other hand, voltage-gated Ca2+ channels were found to be the dominant way of action associated with the vasorelaxant action of chloroquine and cinchonine. Finally, IP3R is found to have only a small impact on the observed activity of the tested compounds. CONCLUSION: Molecular docking studies predicted that chloroquine possesses a significant activity toward a suitable model of LTCCs, while cinchonine does not. The results of the present study point to the fact that great caution should be paid while administering chloroquine to vulnerable patients, especially those with cardiovascular disorders (Tab. 3, Fig. 3, Ref. 28).

Is sleep bruxism in obstructive sleep apnea only an oral health related problem?

BACKGROUND: The etiology of sleep bruxism in obstructive sleep apnea (OSA) patients is not yet fully clarified. This prospective clinical study aimed to investigate the connection between probable sleep bruxism, electromyographic muscle tone, and respiratory sleep patterns recorded during polysomnography. METHODS: 106 patients with OSA (74 males, 31 females, mean age: 56.1 ± 11.4 years) were divided into two groups (sleep bruxism: SB; no sleep bruxism: NSB). Probable SB were based on the AASM criteria: self-report of clenching/grinding, orofacial symptoms upon awakening, abnormal tooth wear and hypertrophy of the masseter muscle. Both groups underwent clinical examination for painful muscle symptoms aligned with Temporomandibular Disorders Diagnostic Criteria (DC/TMD), such as myalgia, myofascial pain, and headache attributed to temporomandibular disorder. Additionally, non-complaint positive muscle palpation and orofacial-related limitations (Jaw Functional Limited Scale-20: JFLS-20) were assessed. A one-night polysomnography with electromyographic masseter muscle tone (EMG) measurement was performed. Descriptive data, inter-group comparisons and multivariate logistic regression were calculated. RESULTS: OSA patients had a 37.1% prevalence of SB. EMG muscle tone (N1-N3, REM; P = 0.001) and the number of hypopneas (P = 0.042) were significantly higher in the sleep bruxism group. While measures like apnea-hypopnea-index (AHI), respiratory-disturbance-index (RDI), apnea index (AI), hypopnea-index (HI), number of arousals, and heart rate (1/min) were elevated in sleep bruxers, the differences were not statistically significant. There was no difference in sleep efficiency (SE; P = 0.403). Non-complaint masseter muscle palpation (61.5%; P = 0.015) and myalgia (41%; P = 0.010) were significant higher in SB patients. Multivariate logistic regression showed a significant contribution of EMG muscle tone and JFLS-20 to bruxism risk. CONCLUSION: Increased EMG muscle tone and orofacial limitations can predict sleep bruxism in OSA patients. Besides, SB patients suffer more from sleep disorder breathing. Thus, sleep bruxism seems to be not only an oral health related problem in obstructive apnea. Consequently, interdisciplinary interventions are crucial for effectively treating these patients. TRIAL REGISTRATION: The study was approved by the Ethics Committee of Philipps-University Marburg (reg. no. 13/22-2022) and registered at the "German Clinical Trial Register, DRKS" (DRKS0002959).

[Rehabilitation of patients with facial nerve neuropathy in cases of increased muscle tone on the healthy side of the face]. / Reabilitatsiya patsientov s neiropatiei litsevogo nerva pri povyshenii tonusa myshts na zdorovoi storone litsa.

OBJECTIVE: To evaluate the effectiveness of physical rehabilitation (PR) and injections of botulinum toxin type A (BTA) in the correction of muscles hypertonicity ty of the healthy side of the face or its prevention in patients with facial nerve neuropathy (FNN). MATERIAL AND METHODS: One hundred and forty-six patients with FNN of various etiologies with muscles hypertonicity of the healthy side or the risk of its development were studied. The term of treatment was 33 [10; 99] days. There are 88 women and 58 men aged 42 [34; 56] years. Diagnosis included clinical examination and stimulation electroneuromyography (ENMG, n=113; 77.4%) with assessment of M-wave amplitude asymmetry. All patients were prescribed a standard PR complex, in addition - relaxation of the muscles of the healthy side by injections of BTA (Incobotulinumtoxin A) - BTA group (n=38) or by special PR techniques - physiotherapy group (n=108). RESULTS: In both groups, patients were comparable in age, sex and severity of FNN at clinical assessment. But objectively, in the BTA group there were more symptomatic forms (63.2% vs 43.5%; p=0.038), cases of M-wave amplitude asymmetry over 90% in ≥2 branches (52.6% vs 18.5%; p=0.032). Displacement of the face midline was a factor limiting recovery (68.4% and 62%; χ2=0.495; p=0.482) in two groups. With amplitude asymmetry of more than 90% in ≥2 branches (a predictor of the risk of unfavorable outcome), a favorable outcome occurred more often in the BTA group (80% versus 45%; χ2=5.227; p=0.023). In case of amplitude asymmetry of less than 90% in all branches, a favorable outcome was observed in two groups. CONCLUSION: Indications for botulinum therapy in patients with FNN are deep prosoparesis or prosoplegia, muscles hypertonicity of the healthy side, displacement of the face midline, ENMG predictors of the risk of unfavorable outcome. PR is an effective method of prevention in patients with a favorable prognosis of outcome or treatment of mild forms.

Tirasemtiv enhances submaximal muscle tension in an Acta1:p.Asp286Gly mouse model of nemaline myopathy.

Nemaline myopathies are the most common form of congenital myopathies. Variants in ACTA1 (NEM3) comprise 15-25% of all nemaline myopathy cases. Patients harboring variants in ACTA1 present with a heterogeneous disease course characterized by stable or progressive muscle weakness and, in severe cases, respiratory failure and death. To date, no specific treatments are available. Since NEM3 is an actin-based thin filament disease, we tested the ability of tirasemtiv, a fast skeletal muscle troponin activator, to improve skeletal muscle function in a mouse model of NEM3, harboring the patient-based p.Asp286Gly variant in Acta1. Acute and long-term tirasemtiv treatment significantly increased muscle contractile capacity at submaximal stimulation frequencies in both fast-twitch extensor digitorum longus and gastrocnemius muscle, and intermediate-twitch diaphragm muscle in vitro and in vivo. Additionally, long-term tirasemtiv treatment in NEM3 mice resulted in a decreased respiratory rate with preserved minute volume, suggesting more efficient respiration. Altogether, our data support the therapeutic potential of fast skeletal muscle troponin activators in alleviating skeletal muscle weakness in a mouse model of NEM3 caused by the Acta1:p.Asp286Gly variant.

The mechanism of action for laryngeal manual therapies: the need for an update.

PURPOSE OF REVIEW: To propose a pathway for expanding the understanding of potential mechanisms of action with laryngeal-based manual therapy (LMT) for muscle tension dysphonia (MTD). This review may help determine if current LMT literature has kept up with advances in the more general manual therapy (MT) findings. RECENT FINDINGS: Studies over the past thirty years, including recently published articles, have confirmed the efficacy of various manual therapy interventions in treating MTD. However, gaps exist between current LMT literature and that being presented in the more general MT field. Instead of viewing peripheral manipulation's influences as a local cause/effect process, the MT literature paints a richer tapestry of centrally mediated impacts. SUMMARY: Evidence from outside the LMT field has introduced a broad tapestry of factors that may contribute to the efficacy of MT, extending beyond the local effects reported in LMT literature. To better understand the effect and mechanism of action touch-based interventions have on a patient's voice and to potentially improve outcomes, it is necessary to broaden investigations to include a broader range of perspectives.

Acute effects of muscle mechanical properties after 2000-m rowing in young male rowers.

Background: The mechanical properties of muscles, such as changes in muscle tone and stiffness, are related to sports performance and injuries. Rowers are at increased risk of muscle fatigue and injury during high-repetition and heavy-load cyclic muscle actions. In view of this, the aim of the present study was to investigate the acute effect on muscle tone and stiffness, as well as bilateral muscle asymmetry, in high school rowers after a 2000-meter rowing ergometer test. Methods: Twelve young male rowers (age = 17.1 ± 0.9 years, body weight = 73.5 ± 9.7 kg) were included in the study. The data of muscle tone (frequency) and stiffness of the posterior deltoids (PD), latissimus dorsi (LD), and rectus femoris (RF) (dominant and non-dominant side) before and after a 2000-m rowing ergometer test were collected using a handheld MyotonPRO device. Results: After the rowing ergometer test, the muscle tone of dominant side PD, LD, and RF were significantly increased (p < 0.05). On the other hand, the muscle stiffness of the non-dominant side LD and RF, as well as the dominant side PD, LD, and RF were significantly increased after the rowing ergometer test (p < 0.05). The muscle tone and stiffness results showed that the dominant side PD, LD, and RF were all significantly higher than the non-dominant side after the rowing ergometer test (p < 0.05), where bilateral PD and RF exhibits moderate asymmetry (5% < symmetry index < 10%). Conclusions: After a high-intensity and high-load 2000-m rowing ergometer test, PD, LD, and RF showed increases in muscle tone and stiffness, as well as changes in the symmetry of bilateral muscle mechanical properties.

The Efficacy of the Manual Circumlaryngeal Therapy for Muscle Tension Dysphonia: A Systematic Review and Meta-analysis.

OBJECTIVE: Muscle tension dysphonia (MTD) is the most common functional voice disorder. Behavioral voice therapy is the front-line treatment for MTD, and laryngeal manual therapy may be a part of this treatment. The objective of this study was to investigate the effect of manual circumlaryngeal therapy (MCT) on acoustic markers of voice quality (jitter, shimmer, and harmonics-to-noise ratio) and vocal function (fundamental frequency) through a systematic review with meta-analysis. DATA SOURCES: Four databases were searched from inception to December 2022, and a manual search was performed. REVIEW METHODS: The PRISMA extension statement for reporting systematic reviews incorporating a meta-analysis of health care interventions was applied, and a random effects model was used for the meta-analyses. RESULTS: We identified 6 eligible studies from 30 studies (without duplicates). The MCT approach was highly effective on acoustics with large effect sizes (Cohen's d > 0.8). Significant improvements were obtained in jitter in percent (mean difference of -.58; 95% CI -1.00 to 0.16), shimmer in percent (mean difference of -5.66; 95% CI -8.16 to 3.17), and harmonics-to-noise ratio in dB (mean difference of 4.65; 95% CI 1.90-7.41), with the latter two measurements continuing to be significantly improved by MCT when measurement variability is considered. CONCLUSION: The efficacy of MCT for MTD was confirmed in most clinical studies by assessing jitter, shimmer, and harmonics-to-noise ratio related to voice quality. The effects of MCT on the fundamental frequency changes could not be verified. Further contributions of high-quality randomized control trials are needed to support evidence-based practice in laryngology. Laryngoscope, 134:18-26, 2024.

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.

Acoustic and Physiologic Correlates of Vocal Effort in Individuals With and Without Primary Muscle Tension Dysphonia.

OBJECTIVES: The aims of this study were to determine relationships between vocal effort and (a) acoustic correlates of vocal output and (b) supraglottic compression in individuals with primary muscle tension dysphonia (pMTD) and without voice disorders (controls) in the context of a vocal load challenge. METHOD: Twenty-six individuals with pMTD and 35 vocally healthy controls participated in a 30-min vocal load challenge. The pre- and postload relationships among self-ratings of vocal effort, various acoustic voice measures, and supraglottic compression (mediolateral and anteroposterior) were tested with multiple regression models and post hoc Pearson's correlations. Acoustic measures included cepstral peak prominence (CPP), low-to-high spectral ratio, difference in intensity between the first two harmonics, fundamental frequency, and sound pressure level (dB SPL). RESULTS: Regression models for CPP and mediolateral compression were statistically significant. Vocal effort, diagnosis of pMTD, and vocal demand were each significant variables influencing CPP measures. CPP was lower in the pMTD group across stages. There was no statistical change in CPP following the vocal load challenge within either group, but both groups had an increase in vocal effort postload. Vocal effort and diagnosis influenced the mediolateral compression model. Mediolateral compression was higher in the pMTD group across stages and had a negative relationship with vocal effort, but it did not differ after vocal loading. CONCLUSIONS: CPP and mediolateral supraglottic compression were influenced by vocal effort and diagnosis of pMTD. Increased vocal effort was associated with lower CPP, particularly after vocal load, and decreased mediolateral supraglottic compression in the pMTD group.

Validity of Accelerometer-Based Sensor System for Muscle Tightness Estimation through Vibration on the Upper Limb.

Spasticity is a condition that profoundly impacts the ability to perform everyday tasks. However, its diagnosis requires trained physicians and subjective evaluations that may vary depending on the evaluator. Focal vibration of spastic muscles has been proposed as a non-invasive, pain-free alternative for spasticity modulation. We propose a system to estimate muscular tightness based on the propagation of elastic waves in the skin generated by focal vibration of the upper limb. The developed system generates focalized displacements on the biceps muscle at frequencies from 50 to 200 Hz, measures the vibration acceleration on the vibration source (input) and the distant location (output), and extracts features of ratios between input and output. The system was tested on 5 healthy volunteers while lifting 1.25 - 11.25 kg weights to increase muscle tone resembling spastic conditions, where the vibration frequency and weight were selected as explanatory variables. An increase in the ratio of the root mean squares proportional to the weight was found, validating the feasibility of the current approach to estimating muscle tightness.Clinical Relevance- This work presents the feasibility of a vibration-based system as an alternative method to objectively diagnose the degree of spasticity.

Between-sexes differences in lumbopelvic muscle mechanical properties of non-climacteric adults: a cross-sectional design.

The lumbopelvic muscle mechanical properties (MMPs) are clinically relevant, but their dependence on sex remains unknown. Therefore, this study aimed to identify if lumbopelvic MMPs depend on the sex in a young adult population. Thirty-five healthy nulliparous women and 35 healthy men were analyzed (age range: 18-50). Lumbopelvic MMPs, that is, tone, stiffness, elasticity, relaxation and creep, assessed with MyotonPRO®, and pelvic floor (PF) health questionnaires were compared between-sexes. Intra-group correlations between sociodemographic and clinical data, and MMPs were also determined. The MMPs of PF were different between healthy non-climacteric adults of both sexes, with women showing higher values of tone and stiffness and lower values of elasticity and viscoelastic properties than men (in all cases, p < 0.03). At lumbar level, tone and stiffness were higher for men at both sides (in all cases, p < 0.04), and relaxation was lower at left side (p = 0.02). The MMPs showed few correlations with sociodemographic data within women. However, within males, there were positive correlations for PF stiffness and viscoelastic parameters with age, BMI and function (0.334 < r < 0.591) and, at lumbar level, negative correlations for tone and stiffness ( - 0.385 < r < -0.590) and positive correlations for viscoelastic properties (0.564 < r < 0.719), with BMI. This indicated that between-sexes differences of lumbopelvic MMPs depend on the specific location of assessment in healthy non-obese young individuals. Women show higher tone and stiffness and lower elasticity and viscoelasticity than men, at PF level.

Analysis of the Relationship Between Muscle Tones and Abnormal Postures in a Computational Model.

Patients with Parkinson's disease (PD), a neurodegenerative disorder, exhibit a characteristic posture known as a forward flexed posture. Increased muscle tone is suggested as a possible cause of this abnormal posture. For further analysis, it is necessary to measure muscle tone, but the experimental measurement of muscle tone during standing is challenging. The aim of this study was to examine the hypothesis that "In patients with PD, abnormal postures are those with a small sway at increased muscle tones" using a computational model. The muscle tones of various magnitudes were estimated using the computational model and standing data of patients with PD. The postures with small sway at the estimated muscle tones were then calculated through an optimization method. The postures and sway calculated using the computational model were compared to those of patients with PD. The results showed that the differences in posture and sway between the simulation and experimental results were small at higher muscle tones compared to those considered plausible in healthy subjects by the simulations. This simulation result indicates that the reproduced sway at high muscle tones is similar to that of actual patients with PD and that the reproduced postures with small sway locally at high muscle tones in the simulations are similar to those of patients with PD. The result is consistent with the hypothesis, reinforcing the hypothesis.Clinical relevance- This study implies that improving the increased muscle tone in patients with PD may lead to an improved abnormal posture.

Quantification of muscle tone by using shear wave velocity during an anaesthetic induction: a prospective observational study.

OBJECTIVES: The quantitative assessment of muscle stiffness or weakness is essential for medical care. Shear wave elastography is non-invasive ultrasound method and provides quantitative information on the elasticity of soft tissue. However, the universal velocity scale for quantification has not been developed. The aim of the study is to determine the shear wave velocities of abdominal muscle during anesthetic induction and to identify methods to cancel the effects of confounders for future development in the quantitative assessment of muscle tone using the universal scale. METHODS: We enrolled 75 adult patients undergoing elective surgery with ASA-PS I - III in the period between December 2018 and March 2021. We measured and calculated the shear wave velocity (SWV) before and after opioid administration (i.e., the baseline at rest and opioid-induced rigidity condition), and after muscle relaxant administration (i.e., zero reference condition). The SWV value was adjusted for the subcutaneous fat thickness by our proposed corrections. The SWVs after the adjustment were compared among the values in baseline, rigidity, and relaxation using one-way repeated-measures ANOVA and post hoc Tukey-Kramer test. A p-value of < 0.05 was considered to be statistically significant. UMIN Clinical Trials Registry identifier UMIN000034692, registered on October 30, 2018. RESULTS: The SWVs in the baseline, opioid-induced rigidity, and muscle relaxation conditions after the adjustment were 2.08 ± 0.48, 2.41 ± 0.60, and 1.79 ± 0.30 m/s, respectively (p < 0.001 at all comparisons). CONCLUSION: The present study suggested that the SWV as reference was 1.79 m/s and that the SWVs at rest and opioid-induced rigidity were ~ 10% and ~ 30% increase from the reference, respectively. The SWV adjusted for the subcutaneous fat thickness may be scale points for the assessment of muscle tone.

Objective Methods of Muscle Tone Diagnosis and Their Application-A Critical Review.

"Muscle tone" is a clinically important and widely used term and palpation is a crucial skill for its diagnosis. However, the term is defined rather vaguely, and palpation is not measurable objectively. Therefore, several methods have been developed to measure muscle tone objectively, in terms of biomechanical properties of the muscle. This article aims to summarize these approaches. Through database searches, we identified those studies related to objective muscle tone measurement in vivo, in situ. Based on them, we described existing methods and devices and compared their reliability. Furthermore, we presented an extensive list of the use of these methods in different fields of research. Although it is believed by some authors that palpation cannot be replaced by a mechanical device, several methods have already proved their utility in muscle biomechanical property diagnosis. There appear to be two issues preventing wider usage of these objective methods in clinical practice. Firstly, a high variability of their reliability, and secondly, a lack of valid mathematical models that would provide the observed mechanical characteristics with a clear physical significance and allow the results to be compared with each other.

Are pelvic pain and increased pelvic floor muscle tone associated in women with persistent noncancer pelvic pain? A systematic review and meta-analysis.

BACKGROUND: The association between pelvic pain and pelvic floor muscle (PFM) tone in women with persistent noncancer pelvic pain (PNCPP) is unclear. AIM: To synthesize the evidence of the association between pelvic pain and PFM tone in women with PNCPP. METHODS: A systematic review was conducted via MEDLINE, Emcare, Embase, CINAHL, PsycINFO, and Scopus to identify relevant studies. Studies were eligible if pelvic pain and PFM tone outcome measures were reported among women aged >18 years. The National Heart, Lung, and Blood Institute's Quality Assessment Tool for Observational Cohort and Cross-sectional Studies was used to assess study quality. Studies were pooled by assessment of PFM tone via a random effects model. Associations between the presence of pelvic pain and PFM tone were assessed with odds ratio (OR), while linear associations were assessed with Pearson or Spearman correlation. OUTCOMES: Pelvic pain measures (intensity, threshold, and frequency) and resting PFM tone in women with PNCPP, as evaluated by any clinical assessment method or tool. RESULTS: Twenty-four studies were included in this review. The presence of pelvic pain was significantly associated with increased PFM tone as assessed by digital palpation (OR, 2.85; 95% CI, 1.66-4.89). Pelvic pain intensity was inversely but weakly associated with PFM flexibility when evaluated through dynamometry (r = -0.29; 95% CI, -0.42 to -0.17). However, no significant associations were found between pelvic pain and PFM tone when measured with other objective assessment methods. CLINICAL IMPLICATIONS: Pelvic pain and increased PFM tone may not be directly associated; alternatively, a nonlinear association may exist. A range of biopsychosocial factors may mediate or moderate the association, and clinicians may need to consider these factors when assessing women with PNCPP. STRENGTHS AND LIMITATIONS: This review was reported according to the PRISMA guidelines. All possible findings from relevant theses and conference abstracts were considered in our search. However, nonlinear associations between pelvic pain and increased PFM tone were not assessed as part of this review. CONCLUSION: Pelvic pain may be linearly associated with increased PFM tone and decreased PFM flexibility when measured with digital palpation or dynamometry; however, this association was not observed when other aspects of PFM tone were assessed through objective methods. Future studies are required using robust assessment methods to measure PFM tone and analyses that account for other biopsychosocial factors that may influence the association.

Quantification of False Vocal Fold Hyperfunction During Quiet Breathing in Muscle Tension Dysphonia.

BACKGROUND/OBJECTIVES: False vocal fold (FVF) hyperfunction during phonation is thought to be a diagnostic sign of primary muscle tension dysphonia (pMTD). However, hyperfunctional patterns with phonation are also observed in typical speakers. This study tested the hypothesis that FVF posturing during quiet breathing, as measured by the curvature of FVF, could differentiate patients with pMTD from typical speakers. METHODS: Laryngoscopic images were collected prospectively in 30 subjects with pMTD and 33 typical speakers. Images were acquired at the end of expiration and maximal inspiration during quiet breathing, during sustained /i/, and during loud phonation before and after a 30-min vocal loading task. The FVF curvature (degree of concavity/convexity) was quantified using a novel curvature index (CI, >0 for hyperfunctional/convex, <0 for "relaxed"/concave) and compared between the two groups. RESULTS: At end-expiration, the pMTD group adopted a convex FVF contour, whereas the control group adopted a concave FVF contour (mean CI 0.123 [SEM 0.046] vs. -0.093 [SEM 0.030], p = 0.0002) before vocal loading. At maximal inspiration, the pMTD group had a neutral/straight FVF contour, whereas the control group had a concave FVF contour (mean CI 0.012 [SEM 0.038] vs. -0.155 [SEM 0.018], p = 0.0002). There were no statistically significant differences in FVF curvature between groups in either the sustained voiced or loud conditions. Vocal loading did not change any of these relationships. CONCLUSIONS: A hyperfunctional posture of the FVFs during quiet breathing especially at end-expiration may be more indicative of a hyperfunctional voice disorder than supraglottic constriction during voicing. LEVEL OF EVIDENCE: 3 Laryngoscope, 133:3449-3454, 2023.

Extrinsic Laryngeal Muscle Tension in Primary Muscle Tension Dysphonia with Shear Wave Elastography.

OBJECTIVES: It has been assumed that patients with primary muscle tension dysphonia (pMTD) have more extrinsic laryngeal muscle (ELM) tension, but tools to study this phenomenon lack. Shear wave elastography (SWE) is a potential method to address these shortcomings. The objectives of this study were to apply SWE to the ELMs, compare SWE measures to standard clinical metrics, and determine group differences in pMTD and typical voice users before and after vocal load. METHODS: SWE measurements of the ELMs from ultrasound examinations of the anterior neck, supraglottic compression severities from laryngoscopic images, cepstral peak prominences (CPP) from voice recordings, and self-perceptual ratings of vocal effort and discomfort were obtained in voice users with (N = 30) and without (N = 35) pMTD, before and after a vocal load challenge. RESULTS: ELM tension significantly increased from rest-to-voiced conditions in both groups. However, the groups were similar in their ELM stiffness levels at SWE at baseline, during vocalization, and post-vocal load. Levels of vocal effort and discomfort and supraglottic compression were significantly higher and CPP was significantly lower in the pMTD group. Vocal load had a significant effect on vocal effort and discomfort but not on laryngeal or acoustic patterns. CONCLUSION: SWE can be used to quantify ELM tension with voicing. Although the pMTD group reported significantly higher levels of vocal effort and vocal tract discomfort and, on average, exhibited significantly more severe supraglottic compression and lower CPP values, there were no group differences in levels of ELM tension using SWE. LEVEL OF EVIDENCE: 2 Laryngoscope, 133:3482-3491, 2023.

[Effect of "Tiaoshen Tongluo" acupuncture on nerve function injury, muscle tension and neurotransmitters through Nrf2/ROS pathway in spastic rats after stroke].

OBJECTIVE: To observe the effect of "Tiaoshen Tongluo" acupuncture (TTA) at "Dingzhongxian" (MS5) and right "Dingpangxian" (MS8) on neurological injury, muscle tension and neurotransmitters through nuclear transcription factor E2 related factor 2 (Nrf2)/reactive oxygen species (ROS) signaling pathway in spastic rats after stroke, so as to explore its mechanisms underlying relief of post-stroke spasm (PSS). METHODS: A total of 90 male SD rats were randomly divided into 6 groups, i.e. sham operation, PSS model, medication, non-acupoint acupuncture, TTA, TTA+ML385 groups, with 15 rats in each group. The PSS model was established by middle cerebral artery occlusion. After modeling, rats of the medication group were treated by gavage of baclofen (0.4 mg/kg), once daily for 7 days. For rats of the non-acupoint acupuncture group, the spot about 10 mm above the iliac crest and below the armpit of the affected side was needled, and for those of the TTA group and TTA+ML385 group, EA stimulation (1 mA, 2 Hz/15 Hz) was applied to MS5 and right MS8 for 10 min, once daily for 7 consecutive days. Intraperitoneal injection of ML385 ［ a specific nuclear factor erythroid 2-related factor 2 (Nrf2) inhibitor, 30 mg/kg］ was given to rats of the TTA+ML385 group before TTA was performed. The rats' neurological deficit score (0-4 points) was evaluated by referring to Zea Longa's methods and the muscular spasm degree of the quadriceps femoris of the left hindlimb (0-4 points) assessed by using Ashworth scale (MAS). The muscular tension of the left quadriceps femoris was measured by using a tension sensor, and Hoffman (H)-reflex response and M and H waves of electromyogram of the muscle between the metatarsals of the left foot were measured using an electrophysiological recorder. The cerebral infarction volume was measured after 2,3,5-triphenyltetrazolium chloride (TTC) staining. The contents of γ-aminobutyric acid (GABA), glycine (Gly), glutamic acid (Glu) and aspartic acid (Asp) of the right cortical infarct area were detected by using high performance capillary electrophoresis, and the contents of 5-hydroxytryptamine (5-HT), dopamine (DA) and norepinephrine (NE) were detected by fluorescence spectrophoto-metry, as well as the level of ROS in the right cerebral cortical infarction tissues was detected by dihydroethidium staining. The expression levels of Nrf2 and heme oxygenase-1 (HO-1) proteins in the infarcted cerebral area were detected using Western blot. RESULTS: Compared with the sham operation group, the neurological deficit score, MAS score, percentage of cerebral infarction volume, Hmax/Mmax ratio, contents of Glu and Asp and ROS level were significantly increased (P<0.001), whereas the muscle tone, stimulation threshold for inducing H-reflex, GABA, Gly, 5-HT, DA and NE contents, cerebral Nrf2 and HO-1 protein expression levels were apparently decreased (P<0.001) in the model group. In comparison with the model group, the neurological deficit score, MAS score, percentage of cerebral infarction volume, Hmax/Mmax ratio, contents of Glu, Asp and ROS levels were decreased (P<0.001), and the muscle tone, stimulation threshold for inducing H-reflex, GABA, Gly, 5-HT, DA and NE contents, Nrf2 and HO-1 protein expressions were increased (P<0.001, P<0.01) in both the medication and TTA groups. No significant differences were found between the non-acupoint group and model group, and between the medication and TTA groups in all the indexes mentioned above (P>0.05). After administration of ML385, the effects of TTA in reducing neurological deficit score, MAS score, Hmax/Mmax, percentage of cerebral infarct volume, Glu, Asp, ROS, and up-regulating H-reflex threshold, GABA, Gly, 5-HT, DA, NE, Nrf2 and HO-1 levels were eliminated (P<0.001，P<0.05,P<0.01). CONCLUSION: TTA can improve neurological behavior and muscle spasm in rats with PSS, which may be associated with its functions in regulating the levels of neurotransmitters in the cortical infarcted area by activating the Nrf2/ROS signaling pathway.

Use of Motion Capture Technology to Study Extrinsic Laryngeal Muscle Tension and Hyperfunction.

OBJECTIVES: Patients with primary muscle tension dysphonia (pMTD) commonly report paralaryngeal pain and discomfort, and extrinsic laryngeal muscle (ELM) tension and hyperfunction are commonly implicated. However, quantitative physiological metrics to study ELM movement patterns for the characterization of pMTD diagnosis and monitoring of treatment progress are lacking. The objectives of this study were to validate motion capture (MoCap) technology to study ELM kinematics, determine whether MoCap could distinguish ELM tension and hyperfunction between individuals with and without pMTD, and investigate relationships between common clinical voice metrics and ELM kinematics. METHODS: Thirty subjects (15 with pMTD and 15 controls) were recruited for the study. Sixteen markers were placed on different anatomical landmarks on the chin and anterior neck. Movements across these regions were tracked during four voice and speech tasks using two three-dimensional cameras. Movement displacement and variability were determined based on 16 key-points and 53 edges. RESULTS: Intraclass correlation coefficients demonstrated high intra- and inter-rater reliability (p's < 0.001). Other than greater movement displacements around the thyrohyoid space during longer phrasing (reading passage, 30-s diadochokinetics) and more movement variability in patients with pMTD, kinematic patterns between groups were similar across the 53 edges for the four voice and speech tasks. There were also no significant correlations between ELM kinematics and standard voice metrics. CONCLUSION: Results demonstrate the feasibility and reliability of MoCap for the study of ELM kinematics. LEVEL OF EVIDENCE: 3 Laryngoscope, 133:3472-3481, 2023.