Predictors of injection laryngoplasty volume for glottic insufficiency.

PURPOSE: Volume injected for glottic insufficiency is paramount in achieving desired outcome. Factors that determine the required volume have not been thoroughly investigated and may correlate with outcome. The first objective of this investigation was to evaluate the association between injectable volume and various parameters, including lifestyle characteristics, pre-procedural factors, and voice measures, while the second aim assessed the correlation of volume to clinical outcomes in patients who underwent injection laryngoplasty. METHODS: For the first objective, a one-way ANOVA and univariate linear regression were used to analyze data from 124 patients (injected material, pre-operative diagnosis, previous voice therapy, age etc.). One-sample t-tests and Pearson correlational coefficients were employed for statistical analysis of aim 2 in a subgroup of 28 patients that had pre- and post-injection voice evaluations (e.g., acoustic and aerodynamic analysis, perceptual assessment, questionnaires). RESULTS: Average injection volume was 0.39 ± 0.062 mL (range: 0.1-1.6mL). No pre-procedural or lifestyle factor significantly affected injection volume (p > 0.05). There was no relationship between pre-procedural voice outcomes and injection volume (p > 0.05). Of the factors that were significantly improved post-injection laryngoplasty (GFI, VHI, and GRBAS), there were no significant correlations between the magnitude of improvement in these measures and injection volume (p > 0.05). CONCLUSION: Injection volume does not appear to be affected by pre-procedural or lifestyle factors. In addition, injection volume does not significantly impact clinical outcomes assessed through voice analysis or patient-reported questionnaires. Our results underscore the complexity of factors at play in injection laryngoplasty for glottic insufficiency.

Water Versus Electrolyte Rehydration on Vocal Fold Osmotic and Oxidative Stress Gene Expression.

OBJECTIVES: Systemic dehydration may induce osmotic and oxidative stress in the vocal folds, but our knowledge of the biology and mitigation with rehydration is limited. The purpose of this experiment was to evaluate whether systemic dehydration induces vocal fold oxidative and osmotic stress and to compare the impact of rehydration by water intake versus electrolyte intake on osmotic and oxidative stress-related gene expression. METHODS: Four-month-old male Sprague-Dawley rats (N = 32) underwent water restriction. Rehydration was achieved with ad libitum access to water or electrolytes for 24 hours. Rats were divided into four groups: euhydration control, dehydration-only, dehydration followed by either water or electrolyte rehydration (n = 8/group). Gene expression was assessed via RT2 Gene Expression Profiler arrays. RESULTS: With respect to oxidative stress, 10 genes were upregulated and 2 were downregulated after vocal fold dehydration compared with the euhydrated control. Concerning osmotic stress, six genes were upregulated with dehydration only, six genes were upregulated following rehydration with water, whereas a single gene was upregulated with electrolyte rehydration. All genes with significantly different expression between the rehydration groups showed lower expression with electrolytes compared with water. CONCLUSIONS: The results support a potential role of oxidative and osmotic stresses in vocal folds related to systemic dehydration. The differences in stress-related gene expression in vocal fold tissue between rehydration with electrolytes or water, albeit modest, suggest that both rehydration options offer clinical utility to subjects experiencing vocal fold dehydration with preliminary evidence that electrolytes may be more effective than water in resolving osmotic stress. LEVELS OF EVIDENCE: NA (prospective animal study) Laryngoscope, 2024.

Contribution of Streptococcus pseudopneumoniae and Streptococcus salivarius to vocal fold mucosal integrity and function.

Structural changes to the vocal fold (VF) epithelium, namely, loosened intercellular junctions, have been reported in VF benign lesions. The potential mechanisms responsible for the disruption of cell junctions do not address the contribution of resident microbial communities to this pathological phenomenon. In this study, we focused on determining the relationship between Streptococcus pseudopneumoniae (SP), a dominant bacterial species associated with benign lesions, and Streptococcus salivarius (SS), a commensal bacterium, with human VF epithelial cells in our three-dimensional model of the human VF mucosa. This experimental system enabled direct deposition of bacteria onto constructs at the air/liquid interface, allowing for the assessment of bacterium-host interactions at the cellular, molecular and ultrastructural levels. Our findings demonstrate that SP disrupts VF epithelial integrity and initiates inflammation via the exported products HtrA1 and pneumolysin. In contrast, SS attaches to the VF epithelium, reduces inflammation and induces Mmp2-mediated apical desquamation of infected cells to mitigate the impact of pathogens. In conclusion, this study highlights the complexity of microbial involvement in VF pathology and potential VF mucosal restoration in the presence of laryngeal commensals.

Age and sex-related variations in murine laryngeal microbiota.

The larynx undergoes significant age and sex-related changes in structure and function across the lifespan. Emerging evidence suggests that laryngeal microbiota influences immunological processes. Thus, there is a critical need to delineate microbial mechanisms that may underlie laryngeal physiological and immunological changes. As a first step, the present study explored potential age and sex-related changes in the laryngeal microbiota across the lifespan in a murine model. We compared laryngeal microbial profiles of mice across the lifespan (adolescents, young adults, older adults and elderly) to determine age and sex-related microbial variation on 16s rRNA gene sequencing. Measures of alpha diversity and beta diversity were obtained, along with differentially abundant taxa across age groups and biological sexes. There was relative stability of the laryngeal microbiota within each age group and no significant bacterial compositional shift in the laryngeal microbiome across the lifespan. There was an abundance of short-chain fatty acid producing bacteria in the adolescent group, unique to the laryngeal microbiota; taxonomic changes in the elderly resembled that of the aged gut microbiome. There were no significant changes in the laryngeal microbiota relating to biological sex. This is the first study to report age and sex-related variation in laryngeal microbiota. This data lays the groundwork for defining how age-related microbial mechanisms may govern laryngeal health and disease. Bacterial compositional changes, as a result of environmental or systemic stimuli, may not only be indicative of laryngeal-specific metabolic and immunoregulatory processes, but may precede structural and functional age-related changes in laryngeal physiology.

A Review of Factors Associated with Voice Problems in the Fitness Instructor Population.

There is a high prevalence of reported dysphonia symptomology in the fitness instructor population. This is concerning as these reported symptoms of dysphonia, aphonia, and vocal fatigue can significantly compromise quality of life. The purpose of this review is to explore key factors that may contribute to voice problems in the fitness instructor population. Voicing with concurrent phonation and exercise may be influenced by (1) the increased cardiovascular requirement during exercise, (2) the increased cognitive load associated with dual tasking, (3) the altered hydration state associated with prolonged exercise, and (4) the phonatory dose associated with continued voicing with loud background music. This manuscript will explore the literature on these key factors (ie, phonatory dose, dehydration, metabolic bioenergetics, cognitive load, and psychosocial stress) as they pertain to fitness instructors.

The role of systemic dehydration in vocal fold healing: Preliminary findings.

Rationale: Systemic dehydration negatively alters the expression of vocal fold inflammatory and cell junction markers. These biological changes can have downstream effects on the healing processes of injured vocal folds. In the dermis, reduced hydration prolongs inflammation and delays healing. It is unknown whether this biological effect is observed in vocal fold tissue. Objective: To investigate the effects of systemic dehydration on vocal fold healing outcomes following acute, bilateral vocal fold injury in a rodent model. Methods: Eighteen systemic dehydrated and 18 euhydrated adult male Sprague Dawley rats experienced bilateral vocal fold injuries or no injury (N = 9/group). Vocal fold gene expression levels of inflammatory mediators and epithelial cell junction markers were measured 24 h post-injury. Results: Pro-inflammatory gene markers (IL-1ß; TNF-α) were differentially expressed in response to systemic dehydration with vocal fold injury compared to non-injury. Epithelial cell junction markers (Cadherin-3, Desmoglein-1) also exhibited divergent trends following systemic dehydration, but these data were not statistically significant. Conclusions: Systemic dehydration may affect cellular vocal fold healing processes within 24 h. These findings lay the groundwork for further investigation of how hydration status can affect vocal fold tissue recovery and influence clinical care.

Eliciting and Characterizing Porcine Vocalizations: When Pigs Fly.

BACKGROUND/OBJECTIVES: While voice-related therapeutic interventions are often researched preclinically in the porcine model, there are no well-established methods to induce porcine glottic phonation. Described approaches, such as training animals to phonate for positive reinforcement are time-consuming and plagued by inherent variability in the type of phonation produced and contamination of background noise. Thus, a reliable method of assessing glottic phonation in the porcine model is needed. METHODS: In this study, we have created a novel pulley-based apparatus with harness for "pig-lifting" with surrounding acoustic insulation and high-directional microphone with digital recorder for recording phonation. Praat and Matlab were used to analyze all porcine vocalizations for fundamental frequency (F0), intensity, duration of phonation and cepstral peak prominence (CPP). Glottic phonation was detected using F0 (≥2000 hz), duration (≥3 seconds) and researcher perceptual judgment. Partial-glottic phonations were also analyzed. Reliability between researcher judgment and acoustic measures for glottic phonation detection was high. RESULTS: Acoustic analysis demonstrated that glottic and partial-glottic phonation was consistently elicited, with no formal training of the minipigs required. Glottic vocalizations increased with multiple lifts. Glottic phonation continued to be elicited after multiple days but became less frequent. Glottic and partial-glottic phonations had similar CPP values over the 6 experimental days. CONCLUSION: Our cost-effective, reliable method of inducing and recording glottic phonation in the porcine model may provide a cost effective, preclinical tool in voice research.

Are Indoor Cycling Instructors Riding Their Way to Vocal Injury? Acute Effects of a Single Class on Measures of Voice Production.

OBJECTIVE/HYPOTHESIS: There is an increased need for vocal education programs in group fitness instructors due to the reported risk of phonotraumatic injury in this population. Most research has focused on aerobics class instructors with limited research detailing the vocal demand response of cycling instruction, specifically. We hypothesized that instruction of a single indoor cycling class would produce evidence of acute vocal fold edema manifested by worsening of acoustic and self-perceptual voice measures and changes in ratings of laryngeal appearance. STUDY DESIGN: Prospective Cohort study. METHODS: Acoustic and self-perceptual voice measures that were potentially sensitive to laryngeal edema were collected from ten cycling instructors (Mean age: 31 ± 6.14 years, 3M and 7F) before and after instruction of a typical 45-minute cycling class. Two laryngologists then rated pairs of laryngeal exams from five instructors (Mean age: 30 ± 6.22 years, 1M and 4F) on the measure of vocal fold edema using a 10-inch Visual Analogue Scale. Paired t-test comparisons were completed on normalized data to compare pre- and postinstruction. RESULTS: Majority of acoustic and self-perceptual measures significantly worsened following cycling instruction but the magnitude of change in these measures were small. In terms of laryngeal appearance, no measurable change in vocal fold edema was observed at both time points. CONCLUSION: The vocal demand response to a single cycling class may be insufficient to cause significant vocal fold edema in our cycling instructors. Future research is required to determine the effects of repeated cycling instruction.

Determining the Underlying Relationship Between Swallowing and Maximum Vocal Pitch Elevation: A Preliminary Study of Their Hyoid Biomechanics in Healthy Adults.

Purpose Deficiencies in swallowing (aspiration) and in maximum vocal pitch elevation have been shown to correlate in dysphagia. However, the underlying mechanisms that may explain this relationship are not known. In this study, we compare hyoid kinematics between swallowing and maximum vocal pitch elevation in healthy adults. Method Ten young (M = 21 ± 1.33 years) and eight older (M = 72.85 ± 5.59 years) healthy adults completed trials of maximum vocal pitch elevation (vowels /a/ and /i/) and swallowing (thin liquid and pudding) under videofluoroscopy. Superior and anterior hyoid excursions were obtained using kinematic analysis. Two-way analyses of variance and Spearman rho correlations were used to examine differences and relationships between swallowing and maximum pitch elevation biomechanics. Results Superior hyoid excursion was significantly greater for liquid swallows compared to pitch elevation tasks (/a/ and /i/; p = .002; Cohen's d = 1.28; p = .0179, Cohen's d = 1.03, respectively) and for pudding swallows compared to pitch tasks (p = .000, Cohen's d = 1.64; p = .001, Cohen's d = 1.38, respectively). Anterior hyoid excursion was not significantly different between the two functions, but was overall reduced in the older group (p = .0231, Cohen's d = .90). Furthermore, there was a moderate positive correlation between the degree of superior excursion during liquid swallows and maximum pitch elevation for both vowels (r s = .601, p = .001; r s = .524, p = .003) in young adults, and between the degree of anterior excursion during liquid swallows and pitch elevation for both vowels (r s = .688, p = .001; r s = .530, p = .008) in older adults. Conclusions Swallowing and maximum pitch elevation require similar anterior, but not superior, hyoid excursion in healthy adults. Differential correlations between the two tasks for each age group may be associated with age-related muscle changes. We provide evidence of partially shared biomechanics between swallowing and maximum pitch elevation.

Body Mass Index and Age Affect Maximum Mouth Opening in a Contemporary American Population.

PURPOSE: Although a standard cutoff value of less than 35 mm in the maximum mouth opening (MMO) has been used to diagnose trismus, this value does not account for natural demographic variations. The present cross-sectional study investigated the effects of age, weight, height, body mass index (BMI), and gender on the MMO in a healthy, heterogeneous population. MATERIALS AND METHODS: A volunteer sample from multiple sites in Cincinnati, Ohio, without any reported head and neck pathologies or current dental prostheses and with intact natural incisors were included. The main outcome measure was the average MMO. Key demographic information was collected from each participant. Multivariate regression analysis was completed on the factors of age, gender, weight, and height. One-way analysis of variance was completed for binned categories of BMI. RESULTS: Data from 330 participants (age range, 18 to 86 years; mean, 42.13 ± 18.53 years; 171 men, 159 women) were collected. The range of MMO was 31 to 71 mm. Age, height, and weight were significant predictors of the MMO, and the final model accounted for ∼20% of the variation in the MMO [adjusted r2, 0.208; F(3,326) = 29.731; P = .001]. On average, individuals with a greater BMI had a greater MMO (BMI, ≤25 kg/m2, 50.57 ± 7.16 mm; BMI >25 but ≤30 kg/m2, 51.58 ± 7.13 mm; BMI >30 kg/m2, 53.53 ± 9.84 mm). CONCLUSIONS: In a heterogeneous population of healthy adults, natural variations in age, height, and weight significantly affected the MMO.

Continuous Vocal Fry Simulated in Laboratory Subjects: A Preliminary Report on Voice Production and Listener Ratings.

Purpose: Vocal fry is prevalent in everyday speech. However, whether the use of vocal fry is detrimental to voice production is unclear. This preliminary study assessed the effects of using continuous vocal fry on voice production measures and listener ratings. Method: Ten healthy individuals (equal male and female, mean age = 22.4 years) completed 2 counterbalanced sessions. In each session, participants read in continuous vocal fry or habitual voice quality for 30 min at a comfortable intensity. Continuous vocal fry was simulated. Phonation threshold pressure (PTP10 and PTP20), cepstral peak prominence, and vocal effort ratings were obtained before and after the production of each voice quality. Next, 10 inexperienced listeners (equal male and female, mean age = 24.1 years) used visual analog scales to rate paired samples of continuous vocal fry and habitual voice quality for naturalness, employability, and amount of listener concentration. Results: PTP10 and vocal effort ratings increased after 30 min of continuous vocal fry. Inexperienced listeners rated continuous vocal fry more negatively than the habitual voice quality. Conclusions: Thirty minutes of simulated, continuous vocal fry worsened some voice measures when compared with a habitual voice quality. Samples of continuous vocal fry were rated as significantly less employable, less natural, and requiring greater listener concentration as compared with samples of habitual voice quality. Future studies should include habitual users of vocal fry to investigate speech stimulability and adaptation with cueing to further understand pathogenesis of vocal fry.

Vocal Loading and Environmental Humidity Effects in Older Adults.

The goal of this study was to investigate the effects of a vocal loading challenge that combined prolonged speaking, in child-directed voice within a noisy environment, in older adults. An additional goal was to determine whether increased environmental humidity would attenuate the negative effects of this vocal loading challenge. METHOD: Thirteen healthy subjects (five males and eight females; >65 years) completed a vocal loading challenge. The challenge involved 45 minutes of child-directed speech in the presence of 65 dB multitalker babble background noise. Subjects completed this challenge in both low humidity and moderate humidity in counterbalanced order. Vocal function was assessed before and after the challenge using phonation threshold pressure (PTP), cepstral peak prominence (CPP), low/high spectral ratio (LHR), perceived phonatory effort (PPE), and perceived vocal tiredness. RESULTS: Negative changes were observed in the aging larynx following the 45-minute vocal loading challenge. Measures of PTP, PPE, and perceived vocal tiredness demonstrated statistically significant loading effects. Increased ambient humidity significantly alleviated the negative changes observed in PPE and perceived vocal tiredness. Increased humidity significantly improved CPP measures both before and after the vocal loading challenge. CONCLUSIONS: This study furthers our understanding of how older adults respond to a vocal loading challenge of prolonged nonhabitual speech in a noisy environment. Our data suggest that the aging voice is negatively affected by prolonged loud speaking and that humidification may be beneficial in reducing some of these negative effects.