The laryngeal neuromuscular mechanisms for modulating glottal posture and fundamental frequency are of interest in understanding normal laryngeal physiology and treating vocal pathology. The intrinsic laryngeal muscles in an in vivo canine model were electrically activated in a graded fashion to investigate their effects on onset frequency, phonation onset pressure, vocal fold strain, and glottal distance at the vocal processes. Muscle activation plots for these laryngeal parameters were evaluated for the interaction of following pairs of muscle activation conditions: (1) cricothyroid (CT) versus all laryngeal adductors (TA/LCA/IA), (2) CT versus LCA/IA, (3) CT versus thyroarytenoid (TA) and, (4) TA versus LCA/IA (LCA: lateral cricoarytenoid muscle, IA: interarytenoid). Increases in onset frequency and strain were primarily affected by CT activation. Onset pressure correlated with activation of all adductors in activation condition 1, but primarily with CT activation in conditions 2 and 3. TA and CT were antagonistic for strain. LCA/IA activation primarily closed the cartilaginous glottis while TA activation closed the mid-membranous glottis.

Objectives-To assess accuracy of the indentation method for stiffness measurements and to estimate the Young's modulus of the vocal fold using this technique. Study Design-Basic science.Methods-Indentation tests were performed using a range of indenter diameters and indentation depths on single and double layer silicone rubber models with a range of cover layer thicknesses with known geometry and Young's moduli. Measurements were repeated on intact vocal folds and isolated muscle and cover layer samples from three cadaveric human larynges.Results-Indentation on single-layer rubber models yielded Young's moduli with acceptable accuracy when the indentation depth was equal to or smaller than the indenter diameter, and both were smaller than the physical dimensions of the material sample. On two-layer models the stiffness estimation was similarly influenced by indenter diameter and indentation depth, and acceptable accuracy was reached when indentation depth was much smaller than the height of the top cover layer. Measurements on mid-membranous vocal fold tissue revealed location-dependent Young's moduli (in kPa) as follows: intact hemilarynx 8.6 (range 5.3 -13.1), isolated inferior medial surface cover 7.5 (range 7 -7.9), isolated medial surface cover 4.8 (range 3.9-5.7), isolated superior surface cover 2.9 (range 2.7 -3.2), and isolated thyroarytenoid muscle 2.0 (range 1.3 -2.7).Conclusions-Indenter diameter, indentation depth, and material thickness are important parameters in measurement of vocal fold stiffness using the indentation technique. Measurements on human larynges showed location-dependent differences in stiffness. The stiffness of the vocal folds was also found to be higher when the vocal fold structure was still attached to the laryngeal framework as compared to when the vocal fold was separated from the framework.

Objectives/Hypothesis: One potential treatment option for severe vocal fold scarring is to replace the vocal fold cover layer with a tissue-engineered structure containing autologous cells. As a first step toward that goal, we sought to develop a three-dimensional cell-populated matrix resembling the vocal fold layers of lamina propria and epithelium.Study Design: Basic science investigation. Methods: Adipose-derived stem cells were cultured in fibrin hydrogels with various growth factors. At the end of the culture period, matrices were sectioned and labeled with immunomarkers to identify cell phenotype.Results: Adipose-derived stem cells survived, attached, and populated three-dimensional fibrin matrices. Under select conditions, a superficial layer of cells expressing epithelial marker proteins overlay a deeper mesenchymal cell layer.Conclusions: A three-dimensional structure of fibrin and adipose-derived stem cells was created as a prototype vocal fold replacement. Two segregated cell phenotypes occurred, producing a bilayered structure resembling epithelium over lamina propria. This preliminary work demonstrates the feasibility of tissue engineering to produce structures for vocal fold replacement.

Objective To compile current best practices regarding tracheostomy decision making, care, and technical performance during the global COVID-19 pandemic. Data Sources Articles listed in PubMed and Google sources for up-to-date information. Review Methods All sources presenting objective evidence related to the topic were reviewed and distilled. Conclusions Tracheostomy in patients with coronavirus disease should be a rare event yet one that requires significant decision making and procedural deliberation. Indications for surgery must be balanced by risk of disease transmission to health care workers. Considerations are given to personal protective equipment, viral testing, and alternatives. Implications for Practice Otolaryngologists worldwide must be aware of these considerations to provide safe patient care without undue risk to themselves or their hospital coworkers.

Endoscopic surgery for subglottic stenosis is a critical aspect of patient management. Neither surgical technique nor grade of stenosis was seen to alter the surgical intervals. Mitomycin application was associated with an extended time interval between endoscopic treatments.