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Purpose: Vocal fold epithelium is composed of layers of individual epithelial cells joined by junctional complexes constituting a unique interface with the external environment. This barrier provides structural stability to the vocal folds and protects underlying connective tissue from injury while being nearly continuously exposed to potentially hazardous insults, including environmental or systemic-based irritants such as pollutants and reflux, surgical procedures, and vibratory trauma. Small disruptions in the epithelial barrier may have a large impact on susceptibility to injury and overall vocal health. The purpose of this article is to provide a broad-based review of current knowledge of the vocal fold epithelial barrier. Method: A comprehensive review of the literature was conducted. Details of the structure of the vocal fold epithelial barrier are presented and evaluated in the context of function in injury and pathology. The importance of the epithelial-associated vocal fold mucus barrier is also introduced. Results/Conclusions: Information presented in this review is valuable for clinicians and researchers as it highlights the importance of this understudied portion of the vocal folds to overall vocal health and disease. Prevention and treatment of injury to the epithelial barrier is a significant area awaiting further investigation.

Purpose: Epithelial homeostasis is critical for vocal fold health, yet little is known about the cells that support epithelial self-renewal. As a known characteristic of stem cells is that they are slow-cycling in vivo, the purpose of this prospective controlled study was to identify and quantify slow-cycling cells or putative stem cells in murine vocal fold epithelium. Method: Twelve mice were administered daily intraperitoneal injections of a nucleotide dye, bromodeoxyuridine (BrdU), over 7 consecutive days. Under this pulse-chase paradigm, slow-cycling cells retain the dye (label-retaining cells; LRCs) while more rapidly cycling cells lose dye to dilution during multiple cell divisions. The percentage of label-retaining cells (%LRCs) was calculated following a chase period of 2, 4, and 8 weeks postinjections. Results: The %LRCs decreased significantly from 9.4% at 2 weeks to 3.1% at 8 weeks following injections (p less than 0.05). No statistically significant differences in the quantity of BrdU-positive cells were measured between the anterior, mid-membranous, or cartilaginous regions of the vocal fold (p greater than 0.05). Conclusion: These findings are consistent with the presence and first report of a small population of putative stem cells along the length of murine vocal fold epithelium.

Purpose: Ion-driven transepithelial water fluxes participate in maintaining superficial vocal fold hydration, which is necessary for normal voice production. The authors hypothesized that Cl[superscript -] channels are present in vocal fold epithelial cells and that transepithelial Cl[superscript -] fluxes can be manipulated pharmacologically. Method: Immunohistochemical assays were used to identify cystic fibrosis transmembrane regulator Cl[superscript -] channels in ovine vocal fold mucosae (n = 2). Electrophysiological responses of vocal fold mucosae (n = 80) to Cl[superscript -] channel inhibitors and secretagogues were evaluated in an ovine model using a randomized controlled experimental design. Results: Cystic fibrosis transmembrane regulator channels were localized to the plasma membranes of epithelial cells. The Cl[superscript -] transport inhibitor, diphenylamine-2-carboxylate, elicited a 30% decrease in mean short-circuit current (I[subscript sc]; n = 10). The secretagogue, isobutylmethylxanthine, yielded a 31.7% increase in mean I[subscript sc] (n = 10). Another secretagogue, uridine triphosphate, elicited a 48.8% immediate and 17.3% sustained increase in mean I[subscript sc] (n = 10). No sustained increases occurred following application of secretagogues to mucosae bathed in a low Cl[superscript -] environment (n = 10), suggesting that responses were Cl[superscript -] dependent. Conclusions: The authors provide structural and functional evidence for the presence of a transepithelial pathway for Cl[superscript -] fluxes. Pharmacological manipulation of this pathway may offer a mechanism for maintaining superficial vocal fold hydration.

This study used visual analog scales to obtain perceptual ratings of features of voice production in subjects with unilateral vocal fold paralysis (UVFP), including clarity of laryngeal articulation, consistency of loudness across the utterance and the voiced/voiceless distinction. Recordings of repeated /i/, /isi/, and /izi/ from subjects diagnosed with UVFP and control subjects were randomly re-recorded, and then rated by five listeners. Significant differences in ratings (Smirnov test, p is less than 0.01) were found between groups for ''aphonia'', ''severity'', ''clarity of articulation'', ''overall loudness'', ''consistency of loudness'' and ''amount of effort''. Four of five raters agreed on the accuracy of /s/ or /z/ productions for only 54% of the samples from the subjects with UVFP. Voiceless and voiced cognates were equally likely to be rated as inaccurate. Results suggested that these variables were sensitive to changes in voice production resulting from paralysis, and may be useful in measuring treatment outcomes and spontaneous recovery of function. Learning outcomes: As a result of reading this manuscript the reader will (1) gain an understanding of types of perceptual scales and how to develop the set of vocal characteristics to be used in distinguishing patients with UVFP and those without, (2) learn which vocal characteristics listeners are able to use to successfully distinguish between patients with UVFP and those without and (3) understand the possible role for perceptual ratings in tracking changes in vocal characteristics in subjects over time following treatment or spontaneous recovery of function.

Summary: Vocal warm-up is thought to optimize singing performance. We compared effects of short-term, submaximal, vocal warm-up exercise with those of vocal rest on the soprano voice (n = 10, [...]

Objectives/hypothesis: Vocal impairments are early and debilitating symptoms of Parkinson's disease (PD). Glottal insufficiency is a contributor to PD-related dysphonia. Vocal fold injection laryngoplasty (IL) and medialization thyroplasty (MT) are well-established techniques used to restore glottal closure for a range of causes. While use of these interventions to improve vocal function in people with Parkinson's disease (PWPD) has been described in literature, a scoping review of the nature, extent, and duration of benefits of procedural intervention to improve vocal fold closure is warranted to provide insight into patient candidacy for vocal fold medialization procedures in addition to standard PD-specific speech therapy protocols., Study Design: Scoping review., Methods: Seven biomedical databases and two gray literature resources were searched to retrieve English-language publications, without restrictions on publication type. Eligibility criteria were diagnosis of participants with PD in adults, presence of a voice concern (eg, dysphonia or glottal insufficiency), and intervention using IL or MT., Results: The search yielded 174 sources of evidence, 18 of which met inclusionary criteria. In total, 13 publications were research studies, three were reviews, one was a conference proceeding, and one was a book chapter. All available auditory-perceptual, quality of life, acoustic, endoscopic, and safety outcomes were tabulated for case studies and case reports. Studies revealed feasibility, and positive, yet varied, short-term outcomes of IL or MT. The quality of research articles was critically appraised using Joanna Briggs Institute checklists revealing trends of incomplete description of participant demographics, nonconsecutive enrollment of participants, absence of control participants, and lack of validity of several outcome measures., Conclusions: Further research, using a rigorous, controlled, blinded, prospective research design to reduce potential bias and improve generalizability of findings is warranted to clarify the benefit of IL and MT, with or without speech therapy, to improve vocal function for PWPD and guide patient selection for vocal fold medialization procedures., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Voice Foundation. Published by Elsevier Inc. All rights reserved.)

Vocal fold epithelial cells are very difficult to study as the vocal fold epithelial cell lines do not exist and they cannot be removed from the healthy larynx without engendering a significant and unacceptable risk to vocal fold function. Here, we describe the procedure to create an engineered vocal fold tissue construct consisting of the scaffold composed of the collagen 1 gel seeded with human fibroblasts and simple epithelial progenitors seeded on the scaffold and cultivated at air-liquid interface for 19-21 days to derive the stratified squamous epithelium. This model of vocal fold mucosa is very similar in morphology, gene expression, and phenotypic characteristics to native vocal fold epithelial cells and the underlying lamina propria and, therefore, offers a promising approach to studying vocal fold biology and biomechanics in health and disease.