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.

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.

Indirect vs Direct Voice Therapy for Children With Vocal Nodules: A Randomized Clinical Trial

Importance

Benign vocal fold nodules affect 12% to 22% of the pediatric population, and 95% of otolaryngologists recommend voice therapy as treatment. However, no randomized clinical trials that we are aware of have shown its benefits.

Objective

To determine the impact of voice therapy in children with vocal fold nodules according to pretherapy and posttherapy scores on the Pediatric Voice-Related Quality of Life (PVRQOL) survey; secondary objectives included changes in phonatory parameters.

Design, Setting, and Participants

For this multicenter randomized clinical trial, 114 children ages 6 to 10 years with vocal fold nodules, PVRQOL scores less than 87.5, and dysphonia for longer than 12 weeks were recruited from outpatient voice and speech clinics. This age range was identified because these patients have not experienced pubertal changes of the larynx, tolerate stroboscopy, and cooperate with voice therapy. Participants were blinded to treatment arm.

Interventions

Participants received either indirect or direct therapy for 8 to 12 weeks. Indirect therapy focused on education and discussion of voice principles, while direct treatment used the stimulus, response, antecedent paradigm.

Main Outcomes and Measures

The primary outcome measure was PVRQOL score change before and after treatment. Secondary phonatory measures were also compared.

Results

Overall, 114 children were recruited for study (mean [SD] age, 8 [1.4] years; 83 males [73%]); with 57 randomized to receive either indirect or direct therapy. Both direct and indirect therapy approaches showed significant differences in PVRQOL scores pretherapy to posttherapy. The mean increase in PVRQOL score for direct therapy was 19.2, and 14.7 for indirect therapy (difference, 4.5; 95.3% CI, -10.8 to 19.8). Of 44 participants in the direct therapy group, 27 (61%) achieved a clinically meaningful PVRQOL improvement, compared with 26 of 49 (53%) for indirect therapy (difference, 8%; 95% CI, -12 to 28). Post hoc stratification showed robust effects in the direct therapy group for older children (Cohen d = 0.50) and the latter two-thirds of participants (Cohen d = 0.46). Vocal fold nodules reduced in size in 31% (22 of 70) and completely resolved in 11% (8 of 70) of participants who consented to a second set of images after going through the recruitment process.

Conclusions and Relevance

Both direct and indirect voice therapy improved voice-related quality of life in children with vocal fold nodules, although there was no significant difference between approaches. Future studies may focus upon which voice therapy approaches are effective in treating age-defined populations.

Trial Registration

clinicaltrials.gov Identifier: NCT01255735.

Retrospective Studies: A Fresh Look

PURPOSE

A first objective was to provide an overview of advantages and cautions around so-called retrospective clinical studies. A second objective was to provide guidelines for strong studies that can make a valid contribution to the clinical literature, whether these studies are prospective, retrospective, experimental, or observational.

METHOD

Invited commentaries were solicited from statistical and study design experts.

RESULTS

The strength of a clinical study does not lie so much with its point in time relative to data generation, as it lies with study design. In fact, quite surprisingly, data collected in the past can be modeled to create a prospective study, if appropriate. One distinctive strength of observational studies-which are sometimes but not always retrospective-is the ability to obtain a large corpus of data from medical databases rapidly, as sometimes warranted by pressing health care policy and practice issues.

CONCLUSION

Retrospective studies, often considered inferior to prospective, randomized, and controlled clinical trials, can have strength and validity often not recognized in the hierarchy of clinical data.