Optical Flow Analysis of Paralaryngeal Muscle Movement.

OBJECTIVES: The paralaryngeal muscles are thought to be hyperfunctional with phonation in patients with primary muscle tension dysphonia (pMTD). However, objective, quantitative tools to assess paralaryngeal movement patterns lack. The objectives of this study were to (1) validate the use of optical flow to characterize paralaryngeal movement patterns with phonation, (2) characterize phonatory optical flow velocities and variability of the paralaryngeal muscles before and after a vocal load challenge, and (3) compare phonatory optical flow measures to standard laryngoscopic, acoustic, and self-perceptual assessments. METHODS: Phonatory movement velocities and variability of the paralaryngeal muscles at vocal onsets and offsets were quantified from ultrasound videos and optical flow methods across 42 subjects with and without a diagnosis of pMTD, before and after a vocal load challenge. Severity of laryngoscopic mediolateral supraglottic compression, acoustic perturbation, and ratings of vocal effort and discomfort were also obtained at both time points. RESULTS: There were no significant differences in optical flow measures of the paralaryngeal muscles with phonation between patients with pMTD and controls. Patients with pMTD had significantly more supraglottic compression, higher acoustic perturbations, and higher vocal effort and vocal tract discomfort ratings. Vocal load had a significant effect on vocal effort and discomfort but not on supraglottic compression, acoustics, or optical flow measures of the paralaryngeal muscles. CONCLUSION: Optical flow methods can be used to study paralaryngeal muscle movement velocity and variability patterns during vocal productions, although the role of the paralaryngeal in pMTD diagnostics (e.g., vocal hyperfunction) remains suspect. LEVEL OF EVIDENCE: 2 Laryngoscope, 134:1792-1801, 2024.

Relationships Between Laryngoscopic Analysis Metrics of Supraglottic Compression and Vocal Effort in Primary Muscle Tension Dysphonia.

PURPOSE: Supraglottic compression is thought to underlie vocal effort in patients with primary muscle tension dysphonia (pMTD). However, the relationship between supraglottic compression and vocal effort in this clinical population remains unclear. Gold standard laryngoscopic assessment metrics for supraglottic compression are also lacking. The goals of this study were to identify metrics proposed in the literature that could distinguish patients diagnosed with pMTD from typical voice users and determine their relationships to the vocal effort. METHODS: Flexible laryngeal endoscopy was performed on 50 participants (25 pMTD, 25 controls). The presence of supraglottic compression was characterized using a categorical (nominal) scale and severity was quantified on ordinal and continuous scales. The three laryngoscopic metrics were correlated with self-perceived ratings of vocal effort on a 100 mm visual analog scale. RESULTS: Inter-rater reliability was strongest for the continuous scale (P's < 0.0001) compared to categorical (P's < 0.001) and ordinal (P's < 0.001) scales. The presence of different supraglottic compression patterns varied in both groups, and there were no significant group differences on categorical (P's > 0.05) scales. Mediolateral (M-L) supraglottic compression was significantly greater in the pMTD group (P < 0.0001), and anteroposterior (A-P) compression was significantly greater in the control group (P = 0.001) using continuous scales. There were no significant relationships between any of the three laryngoscopic metric types and vocal effort ratings (P's > 0.05), except for a significantly positive relationship between anterior-posterior compression on the ordinal scale and vocal effort in the control group (P = 0.047). CONCLUSIONS: Continuous scales are reliable and valid for distinguishing individuals with pMTD from those without voice disorders, especially occupational voice users. M-L supraglottic compression may be a better indicator of pMTD than A-P compression. However, the poor correlation between supraglottic compression and vocal effort suggests that one may not influence the other. Future studies should focus on other mechanisms underlying vocal effort in patients with pMTD.

Patient Profiling: Determining the Effects of Patient Factors on Vocal Fatigue.

OBJECTIVES: The phenomenon of vocal fatigue and the types of patients that are at greatest risk for vocal fatigue are not fully understood. The goal was to investigate patient profiles such as voice disorder type, demographics (age and gender), singing identity, interoceptive awareness, and psychosocial impacts on the severity of vocal fatigue. STUDY DESIGN: Prospective cohort study. METHODS: Ninety-five subjects with voice disorders were asked to complete Part 1 of the Vocal Fatigue Index (VFI-Part1), the Voice Handicap Index-10 (VHI-10), and the Multidimensional Assessment of Interoceptive Awareness, version 2 (MAIA-2). The effects of voice disorder type (structural, neurological, functional), psychosocial impact, age, gender, self-reported singing identity, and interoceptive awareness on self-perceived vocal fatigue (VFI-Part1) were determined using multivariate linear regression. RESULTS: Vocal fatigue had a significant psychosocial impact on patients with voice disorders, as measured by the VHI-10 (P < 0.001). However, there were no significant effects of vocal fatigue across any of the three voice disorder types (P's >0.05). Age (P = 0.220), gender (P = 0.430), and self-identified singing experience (P = 0.360) also did not have significant effects on vocal fatigue. Additionally, there were no significant relationships between interoceptive awareness MAIA-2 sum scores (P = 0.056) or any of the MAIA-2 sub-scores (P's > 0.05) and vocal fatigue severity (VFI-Part1). CONCLUSION: Vocal fatigue has a significant psychosocial impact on patients with voice disorders. However, patient profiles, including voice disorder type, patient age, gender, singing identity, and level of interoceptive awareness do not appear to play a major role in vocal fatigue symptom reporting. These findings suggest caution should be exercised when attributing patient profiles to vocal fatigue presentation and severity. Studying pathophysiological mechanisms underlying vocal fatigue may help better distinguish unconscious bias in patient profiling from the etiology and severity of vocal fatigue.

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.