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.

Ingredients in the Visual Perception of Hypomobile Vocal Fold Motion Impairment.

OBJECTIVES: The clinical determination of vocal fold (VF) hypomobility based on laryngoscopy is subjective. Previous studies point to VF motion anomaly as the most commonly reported factor in the diagnosis of hypomobility. This study tested the hypotheses that VF angular velocities and angular range of motion (ROM) differ between the two VFs in cases of unilateral VF hypomobility. STUDY DESIGN: Retrospective. METHODS: Semi-automated analysis of laryngoscopic videos of 18 subjects diagnosed with unilateral VF hypomobility and 13 subjects with normal VF mobility was performed to quantify/compare the VF angular velocity and ROM between the two VFs during /i/-sniff and laugh. RESULTS: In the hypomobile VF group, 7 out of 15 (47%) videos with /i/-sniff and 5 out of 8 (63%) with laugh had a statistically significant difference in the angular velocities between the VFs in either abduction or adduction. For VF ROM, 8 out of 15 (53%) /i/-sniff videos and 4 out of 8 (50%) with laughter had a statistically significant difference between VFs. In the group without the diagnosis of VF hypomobility, 9 out of 13 subjects (69%) had no difference in VF angular velocity and ROM during either /i/-sniff or laugh. CONCLUSIONS: Differences in VF angular velocity or ROM are measurable in a substantial subset of subjects diagnosed with unilateral VF hypomobility. Clinicians' ability to gauge VF motion goes beyond what can be extracted from frame-by-frame analysis. Other visual cues, in addition to VF angular velocity and ROM, likely contribute to the perception of unilateral VF hypomobility. LEVEL OF EVIDENCE: 3 Laryngoscope, 133:866-874, 2023.

Bisulfite-independent analysis of CpG island methylation enables genome-scale stratification of single cells.

Conventional DNA bisulfite sequencing has been extended to single cell level, but the coverage consistency is insufficient for parallel comparison. Here we report a novel method for genome-wide CpG island (CGI) methylation sequencing for single cells (scCGI-seq), combining methylation-sensitive restriction enzyme digestion and multiple displacement amplification for selective detection of methylated CGIs. We applied this method to analyzing single cells from two types of hematopoietic cells, K562 and GM12878 and small populations of fibroblasts and induced pluripotent stem cells. The method detected 21 798 CGIs (76% of all CGIs) per cell, and the number of CGIs consistently detected from all 16 profiled single cells was 20 864 (72.7%), with 12 961 promoters covered. This coverage represents a substantial improvement over results obtained using single cell reduced representation bisulfite sequencing, with a 66-fold increase in the fraction of consistently profiled CGIs across individual cells. Single cells of the same type were more similar to each other than to other types, but also displayed epigenetic heterogeneity. The method was further validated by comparing the CpG methylation pattern, methylation profile of CGIs/promoters and repeat regions and 41 classes of known regulatory markers to the ENCODE data. Although not every minor methylation differences between cells are detectable, scCGI-seq provides a solid tool for unsupervised stratification of a heterogeneous cell population.