Search

Objective: The laryngeal adductor reflex (LAR) is an important mechanism to secure the airways from potential foreign body aspiration. An involvement of the upper esophageal sphincter (UES) in terms of a laryngo-UES contractile reflex has been identified after laryngeal mucosa stimulation. However, the LAR-UES relationship has not yet been fully explained. This study aimed to determine the magnitude, latency, and occurrence rate of the UES pressure response when the LAR is triggered in order to elucidate the functional relationship between the larynx and the UES., Methods: This prospective study included seven healthy volunteers (5 female, 2 male, age 22-34 years). Laryngeal penetration was simulated by eliciting the LAR 20 times in each individual by applying water-based microdroplets onto the laryngeal mucosa. UES pressures were measured simultaneously using high-resolution manometry., Results: Two distinct pressure phases (P1, P2) associated with the LAR were identified. P1 corresponded with a short-term UES pressure decrease in two subjects and a pressure increase in five subjects occurring 200 to 500 ms after the stimulus. In P2, all subjects experienced an increase in UES pressure with a latency time of approximately 800 to 1700 ms and an average of 40 to 90 mmHg above the UES resting tone., Conclusion: Foreign bodies penetrating the laryngeal inlet lead to a reflex contraction of the UES. Phase P1 could be a result of vocal fold activity caused by the LAR, leading to pressure changes in the UES. The constriction during P2 could strengthen the barrier function of the UES in preparation to a subsequent cough that may be triggered to clear the airways., Level of Evidence: 4 Laryngoscope, 131:E1778-E1784, 2021., (© 2021 The Authors. The Laryngoscope published by Wiley Periodicals LLC on behalf of American Laryngological, Rhinological and Otological Society Inc, "The Triological Society" and American Laryngological Association (ALA).)

The sinonasal mucosa has an essential role in defense mechanisms of the upper respiratory tract. The innate immune system presents the primary defense against noxious microorganisms followed by induction of the adaptive immune mechanisms as a consequence of the presence of pathogens. This well-known activation of adaptive immune system in response to presence of the antigen on mucosal surfaces is now broadly applicated in vaccinology research. Prevention of infectious diseases belongs to substantial challenges in maintaining the population health. Non-invasive, easily applicable mucosal vaccination purposes various research opportunities that could be usable in daily practice. However, the existence of multiple limitations such as rapid clearance of vaccine from nasal mucosa by means of mucociliary transport represents a great challenge in development of safe and efficient vaccines. Here we give an updated view on nasal functions with focus on nasal mucosal immunity and its potential application in vaccination in nearly future.

Introduction: Mucosal impedance testing measures changes in resistance to alternating electrical current. The purpose of this study is to establish the feasibility of mucosal impedance (MI) measurement in the pediatric larynx., Methods: A flexible plastic catheter, whose tip contains paired 2 mm mucosal impedance, is directly applied to the larynx under suspension microlaryngoscopy. Milliohms of resistance is relayed real-time from the catheter and output onto a PC. Results were obtained safely over the course of 5 min of intraoperative time for all 49 patients undergoing routine microlaryngoscopy at a tertiary care pediatric hospital., Results: The technique was successful in identifying MI values with reliable and reproducible results. The risk was minimal with no adverse events occurring. Impedance noise reduction was improved by the use of an aqueous gel coating on the probe and an emphasis on measurements of the interarytenoid space, which enabled the sensor rings to contact 360° of the mucosa., Conclusion: Laryngeal MI can be safely and reliably performed with reproducible measurements and minimal added procedure time., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The upper airways play important roles in respiratory defensive reflexes. Although solitary chemosensory cells and chemosensory cell clusters have been reported in the laryngeal mucosa of mammalian species, the distribution and cellular morphology of chemosensory cells remain unclear. In the present study, the distribution and morphology of solitary chemosensory cells and chemosensory cell clusters were examined by immunofluorescence for GNAT3 on whole-mount preparations of the rat laryngeal mucosa. Electrophysiological experiments were performed to analyze the respiratory reflexes evoked by bitter stimuli to the laryngeal cavity. In the whole area of the laryngeal mucosa, the numbers of GNAT3-immunoreactive solitary chemosensory cells and chemosensory clusters were 421.0 ± 20.3 and 62.7 ± 6.9, respectively. GNAT3-immunoreactive solitary chemosensory cells were mainly distributed in the mucosa overlying epiglottic and arytenoid cartilage, and chemosensory clusters were mainly distributed on the edge of the epiglottis and aryepiglottic fold. GNAT3-immunoreactive solitary chemosensory cells were slender with elongated processes or had a flask-like/columnar shape. The number of GNAT3-immunoreactive cells in chemosensory clusters was 6.1 ± 0.4, ranging between 2 and 14 cells. GNAT3-immunoreactive cells in the cluster were variform and the tips of apical processes gathered at one point at the surface of the epithelium. The tips of apical cytoplasmic processes in solitary chemosensory cells and cells in the cluster were immunoreactive for espin, and faced the laryngeal cavity. Physiological experiments showed that the application of 10 mm quinine hydrochloride to the laryngeal cavity decreased respiratory frequency. The present results revealed the chemosensory field of the larynx and the morphological characteristics of the laryngeal chemosensory system for respiratory depression., (© 2018 Anatomical Society.)

Objective: The purpose of this study was to quantify the viscoelastic shear properties of the human ventricular fold (or false vocal fold) mucosa and aryepiglottic fold mucosa at frequencies of phonation., Methods: Linear viscoelastic shear properties of the mucosa of false vocal fold and aryepiglottic fold specimens from seven cadaveric subjects were determined as functions of frequency (5-250 Hz) and compared to those of the true vocal fold cover. Measurements of elastic shear modulus (G') and dynamic viscosity (η') were made with a controlled-strain simple-shear rheometer. Linear least-squares regression was conducted to curve-fit log G' and log η' versus log frequency, and statistical analysis was performed with one-way analysis of variance., Results: All specimens showed similar frequency dependence of the viscoelastic functions G' and η', with G' gradually increasing with frequency and η' monotonically decreasing with frequency. The magnitudes of G' and η' of the false fold mucosa were generally higher than those of the aryepiglottic fold mucosa and true vocal fold cover, but there were no significant differences in G' and η' among the false fold, aryepiglottic fold, and true vocal fold., Conclusion: The false vocal fold and aryepiglottic fold mucosa showed similar frequency dependence and a similar range of tissue viscoelastic behavior as the true vocal fold. These preliminary findings suggested that such tissues could become candidates for the replacement of the true vocal fold lamina propria in patients with significant tissue loss and deficiencies, for those requiring laryngeal reconstruction following partial laryngectomy or airway reconstruction., Level of Evidence: NA. Laryngoscope, E296-E301, 2018., (© 2017 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives: In this paper, a nonlinear least squares fitting method was proposed to quantify subharmonic mucosal waves., Study Design and Methods: Subharmonic mucosal waves from 10 excised canine larynges were recorded using digital kymography and analyzed using nonlinear least squares and linear least squares methods. Amplitudes of fundamental and subharmonic mucosal wave components of right-upper, right-lower, left-upper, and left-lower vocal fold lips were calculated. Lastly, phase differences of fundamental and subharmonic components of the left and right vocal folds were compared., Results: The results showed that the nonlinear least squares analysis method provides a more effective complement to the linear fitting method for subharmonic mucosal wave extraction. There was a significant difference in amplitudes between the subharmonic and the fundamental components of mucosal waves (P < 0.05). The phase differences of the fundamental and the subharmonic components of the right and left vocal folds were not significantly different., Conclusions: The application of the nonlinear least squares analysis method in digital kymography is useful for the characterization of subharmonic mucosal waves., (Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.)

1. There is growing evidence to suggest that the cells in the maculae flavae are tissue stem cells of the human vocal fold and maculae flavae are a candidate for a stem cell niche. 2. The latest research shows that the cells in the human maculae flavae are involved in the metabolism of extracellular matrices that are essential for the viscoelasticity in the human vocal fold mucosa as a vibrating tissue, and considered to be important cells in the growth, development, and aging of the human vocal fold mucosa. 3. The cells in the human maculae flavae possess proteins of all three germ layers, indicating they are undifferentiated and have the ability of multipotency. 4. The cell division in the human adult maculae flavae is reflective of asymmetric self-renewal and cultured cells form a colony-forming unit. Therefore, the phenomenon gives rise to the strong possibility that the cells in the human maculae flavae are tissue stem cells. 5. Recent research suggests that the cells in the human maculae flavae arise from the differentiation of bone marrow cells via peripheral circulation. 6. The hyaluronan concentration in the maculae flavae is high and contains cells which possess hyaluronan receptors, indicating that the maculae flavae are hyaluronan-rich matrix, which is required for a stem cell niche. 7. A proper microenvironment in the maculae flavae of the human vocal fold mucosa is necessary to be effective as a stem cell niche maintaining the stemness of the contained tissue stem cells.

Objective: To study the wound healing following CO2 laser microsurgery for early glottic cancer, and to evaluate the treatment outcomes and cost-effectiveness of microsurgery, open surgery and radiotherapy for early glottic cancer., Methods: Thirty-six patients with early glottic carcinoma (T1-T2) treated by transoral CO2 laser microsurgery from January 2011 to June 2014 were observed, and 112 patients undergoing open approach and 27 receiving radiotherapy from January 2008 to June 2014 in our hospital were used as control. The wound healing process, the hospital stay, the cost, the oncologic and functional results were evaluated., Results: The mean time of laryngeal mucous membrane stabilization in morphology was 93 days, less than 120 days in 91% cases. The average score of VHI-10 was 5.9, which was better in the cases with T1 than the cases with T2, and was worse in cases with the anterior commissure involvement. Transoral CO2 laser microsurgery offered a similar oncologic result, shorter hospital stay and lower cost compared with open surgery or radiotherapy., Conclusion: The transoral laser surgery could be a better choice for early glottic carcinoma because of good oncologic and functional results and less cost.

This study investigated the impact of selective epithelial injury on phonation in an excised human larynx apparatus. With intact epithelium, the vocal folds exhibited a symmetrical vibration pattern with complete glottal closure during vibration. The epithelium was then enzymatically removed from one, then both vocal folds, which led to left-right asymmetric vibration and a decreased closed quotient. Although the mechanisms underlying these vibratory changes are unclear, these results demonstrate that some component of an intact surface layer may play an important role in achieving normal symmetric vibration and glottal closure.

Objectives: From the perspective of the glottal area and mucosal wave, quantitatively estimate the differences of vocal fold on laryngeal activity during phonation at three different dehydration levels., Study Design: Controlled three sets of tests., Methods: A dehydration experiment for 10 excised canine larynges was conducted at 16 cm H2O. According to the dehydration cycle time (H), dehydration levels were divided into three degrees (0% H, 50% H, 75% H). The glottal area and mucosal wave under three dehydration levels were extracted from high-speed images and digital videokymography (DKG) image sequences. Direct and non-direct amplitude components were derived from glottal areas. The amplitude and frequency of mucosal wave were calculated from DKG image sequences. These parameters in condition of three dehydration levels were compared for statistical analysis., Results and Discussions: The results showed a significant difference in direct (P = 0.001; P = 0.005) and non-direct (P = 0.005; P = 0.016) components of glottal areas between every two different dehydration levels. Considering the right-upper, right-lower, left-upper, and left-lower of vocal fold, the amplitudes of mucosal waves consistently decreased with increasing of dehydration levels. But, there was no significant difference in frequency., Conclusions: Surface dehydration could give rise to complex variation of vocal fold on tissues and vibratory mechanism, which should need analyzing from multiple perspectives. The results suggested that the combination of glottal area and mucosal wave could be better to research the change of vocal fold at different dehydrations. It would become a better crucial research tool for the clinical treatment of dehydration-induced laryngeal pathologies., (Copyright © 2015 The Voice Foundation. Published by Elsevier Inc. All rights reserved.)

Background: The goal of vocal fold wound healing is the reconstitution of functional tissue, including a structurally and functionally intact epithelium. Mechanisms underlying reepithelialization in vocal folds are not known, although it is suspected that healing involves the interplay between several growth factors. We used a three-dimensional human embryonic stem cell-derived model of vocal fold mucosa to examine the effects of one growth factor, exogenous epidermal growth factor (EGF), on wound healing., Materials and Methods: A scratch wound was created in the in vitro model. Rate of wound healing, epidermal growth factor receptor (EGFR) activation, and cell proliferation after injury were analyzed with and without application of both exogenous EGF and an EGFR inhibitor, gefitinib., Results: Wound repair after injury was significantly hastened by application of exogenous EGF (13.3 μm/h, ± 2.63) compared with absence of exogenous EGF (7.1 μm/h ± 2.84), but inhibited with concurrent addition of Gefitinib (5.2 μm/h, ± 2.23), indicating that EGF mediates wound healing in an EGFR-dependent manner. Immunohistochemistry revealed that EGFR activation occurred only in the presence of exogenous EGF. Although not statistically significant, increased density of Ki67 staining in the epithelium adjacent to the scratch wound was observed after treatment with EGF, suggesting a tendency for exogenous EGF to increase epithelial cell proliferation., Conclusions: Exogenous EGF increases the rate of wound healing in an EGFR-dependent manner in a three-dimensional stem cell-derived model of vocal fold mucosa. This model of wound healing can be used to gain insight into the mechanisms that regulate vocal fold epithelial repair after injury., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Laryngeal sensitivity is crucial for maintaining safe swallowing, thus avoiding silent aspiration. The sensitivity test, carried out by fiberoptic endoscopic examination of swallowing, plays an important role in the assessment of dysphagic patients. The ventricular folds appear to be more sensitive than the epiglottis during the sensitivity test. Therefore, this study aimed to investigate the mechanical sensitivity of the supraglottic larynx. In seven healthy adults undergoing microlaryngoscopy to remove vocal cord polyps, we excised mucosal samples from the epiglottis and ventricular folds. We measured afferent nerve fiber density by immunoelectron microscopy. All of the subjects underwent an endoscopic sensitivity test based on lightly touching the laryngeal surface of the epiglottis and ventricular folds. The discomfort level was self-rated by the subjects on the visual analog scale. Samples were fixed and stored in cryoprotectant solution at 4 °C. Sections were stained with the protein gene product 9.5, a pan-neuronal selective marker. Nerve fiber density was calculated as the number of fibers per millimeter length of section. The mean nerve fiber density was higher in ventricular samples than in epiglottis samples (2.96 ± 2.05 vs 0.83 ± 0.51; two-sided p = 0.018). The mean visual analog scale scores were significantly higher for touching the ventricular folds than for touching the epiglottis (8.28 ± 1.11 vs 4.14 ± 1.21; two-sided p = 0.017). The higher sensitivity of the ventricular region should be considered for further refining clinical endoscopic evaluation of laryngeal sensitivity.

An experimental method based on Rayleigh wave propagation was developed for quantifying the frequency-dependent viscoelastic properties of a small volume of expensive biomaterials over a broad frequency range. Synthetic silicone rubber and gelatin materials were fabricated and tested to evaluate the proposed method. Planar harmonic Rayleigh waves at different frequencies, from 80 to 4000 Hz, were launched on the surface of a sample composed of a substrate with known material properties coated with a thin layer of the soft material to be characterized. A transfer function method was used to obtain the complex Rayleigh wavenumber. An inverse wave propagation problem was solved and a complex nonlinear dispersion equation was obtained. The complex shear and elastic moduli of the sample materials were then calculated through the numerical solution of the obtained dispersion equation using the measured wavenumbers. The results were in good agreement with those of a previous independent study. The proposed method was found to be reliable and cost effective for the measurement of viscoelastic properties of a thin layer of expensive biomaterials, such as phonosurgical biomaterials, over a wide frequency range.

Organized vibration of the vocal folds is critical for high-quality voice production. When the vocal folds oscillate, the superficial tissue of the vocal fold is displaced in a wave-like fashion, creating the so-called "mucosal wave." Because the mucosal wave is dependent on vocal fold structure, physical alterations of that structure cause mucosal wave abnormalities. Visualization and quantification of mucosal wave properties have become useful parameters in diagnosing and managing vocal fold pathology. Mucosal wave measurement provides information about vocal fold characteristics that cannot be determined with other assessment techniques. Here, we discuss the benefits, disadvantages, and clinical applicability of the different mucosal wave measurement techniques, such as electroglottography, photoglottography, and ultrasound and visualization techniques that include videokymography, stroboscopy, and high-speed digital imaging. The various techniques and their specific uses are reviewed with the intention of helping researchers and clinicians choose a method for a given situation and understand its limitations and its potential applications. Recent applications of these techniques for quantitative assessment demonstrate that additional research must be conducted to realize the full potential of these tools. Evaluations of existing research and recommendations for future research are given to promote both the quantitative study of the mucosal wave through accurate and standardized measurement of mucosal wave parameters and the development of reliable methods with which physicians can diagnose vocal disorders., (Copyright © 2011 The Voice Foundation. Published by Mosby, Inc. All rights reserved.)

Objectives: Tracheal mucosal perfusion is compromised at an endotracheal tube (ETT) cuff pressure of 30 cm H(2)O, and blood flow is obstructed at a pressure of 50 cm H(2)O., Methods: We measured the change in pressure of air-filled cuffs of 6.0 and 7.5 ETTs and a size 4 laryngeal mask airway (LMA) from sea level to 2400 m. The ETTs and LMA cuff measurements were done with the devices uncontained, and an additional 6.0 ETT was placed in a 10-mL syringe barrel to mimic placement in a trachea. This restricted cuff expansion simulating what would occur when it is placed within the trachea. The pressure of fluid-filled 6.0 ETT cuffs was also measured., Results: Intracuff pressure increases linearly with increasing altitude, in all air-filled ETT and LMAs. Water-filled cuffs demonstrated no significant change in pressure with changes in altitude. The rate of ETT cuff pressure increase was greater for the ETT restricted within the syringe barrel compared with the unrestricted ETT cuff. The rate of LMA cuff pressure increase was greater than the rate of increase for all the ETTs (restricted and unrestricted)., Conclusions: This model indicates that ETT cuffs inflated before air transport are likely to exceed critical pressure levels rapidly during flight. In addition, there will be loss of ETT cuff pressure, with loss of a good seal, during descent if a cuff is initially inflated at peak altitudes. Therefore, we suggest ETT cuff pressures should be monitored and adjusted continuously during ascent and decent.

Objective: Evaluate the effect of vocal fold surface dehydration on mucosal wave amplitude and frequency., Study Design: Controlled test-retest., Setting: Larynges were mounted on an excised larynx phonation system and attached to a pseudolung in a triple-walled sound-attenuated room that eliminated background noise and maintained a stabilized room temperature and humidity level., Subjects and Methods: High-speed video was recorded for 8 excised canine larynges during exposure to dehumidified air at 20 cm H(2)O. Control trials consisted of high-speed videos recorded for 2 excised canine larynges during exposure to humidified air at the same pressure., Results: In the majority of larynges, increased levels of dehydration were correlated with decreased amplitude and frequency. The slope of the linear regression fitted to the change in amplitude (P = .003) and the percent change (P < .001) between the initial and final trials were significantly decreased in dehydrated larynges. These measurements with respect to the change in frequency were also significantly decreased in dehydrated larynges (P < .001; P = .027)., Conclusion: Vocal fold surface dehydration caused a decrease in mucosal wave amplitude and frequency. This study provides objective, quantitative support for the mechanism of voice deterioration observed after extreme surface dehydration.

Objectives: This study aimed to analyse vocal performance and to investigate the nature of the neoglottal sound source in patients who had undergone supracricoid laryngectomy with cricohyoidoepiglottopexy, using a high-speed digital imaging system., Methods: High-speed digital imaging analysis of neoglottal kinetics was performed in two patients who had undergone supracricoid laryngectomy with cricohyoidoepiglottopexy; laryngotopography, inverse filtering analysis and multiline kymography were also undertaken., Results: In case one, laryngotopography demonstrated two vibrating areas: one matched with the primary (i.e. fundamental) frequency (75 Hz) and the other with the secondary frequency (150 Hz) at the neoglottis. In case two, laryngotopography showed two vibrating areas matched with the fundamental frequency (172 Hz) at the neoglottis. The interaction between the two areas was considered to be the sound source in both patients. The waveform of the estimated volume flow at the neoglottis, obtained by inverse filtering analysis, corresponded well to the neoglottal vibration patterns derived by multiline kymography. These findings indicated that the specific sites identified at the neoglottis by the present method were likely to be the sound source in each patient., Conclusions: High-speed digital imaging analysis is effective in locating the sites responsible for voice production in patients who have undergone supracricoid laryngectomy with cricohyoidoepiglottopexy. This is the first study to clearly identify the neoglottal sound source in such patients, using a high-speed digital imaging system.

In this work a detection algorithm for mucosal wave propagation is presented. By incorporating physiological knowledge of mucosal wave properties and taking the segmented lateral movement of both vocal fold edges as a basis, the spatio-temporal position of the traveling mucosal wave is identified and quantitatively captured. The course of mucosal wave propagation can be successfully detected and analyzed with regard to discriminating different types of mucosal wave activity (in terms of spread velocity and symmetry). The preliminary results obtained for six exemplary laryngeal high-speed recordings are promising and demonstrate the potential of the proposed detection and objective description approach.

Background: Early postnatal abnormalities of autonomic nervous system (ANS) activity, including at baseline and following cardiorespiratory challenge, are involved in apneas-bradycardias of prematurity, apparent life-threatening events of infancy and sudden infant death syndrome. Literature data suggest that baseline ANS activity does not mature normally after premature birth., Objectives: This study performed in preterm lambs was aimed at assessing ANS maturation at baseline and following laryngeal chemoreflexes (LCR), a group of reflexes triggered by the contact of liquids with the laryngeal mucosa., Methods: Heart rate variability (HRV) and baroreflex sensitivity (BRs) were measured at baseline and after LCR during polysomnographic recordings performed in five non-sedated lambs born 15 days prematurely. Laryngeal chemoreflexes were induced by distilled water or acid (pH 2) during sleep and wakefulness on postnatal days 7 (D7) and 14 (D14, full-term equivalence)., Results: While the life-threatening cardiorespiratory events of the LCR observed at D7 were no longer present at D14, baseline and post-LCR HRV and BRs indices were significantly lower at D14 compared to D7 (up to p<0.001). These results suggest that an initial autonomic overactivity was present at D7 and normalized at D14., Conclusion: The autonomic cardiac and baroreflex control appears to follow a specific evolution in the preterm compared to the full-term newborn lamb, with an important initial autonomic stress, which normalizes at an age equivalent to full-term. Potential relevance of these findings in relation to anomalies of cardiac control in the early postnatal period, such as apneas-bradycardias of prematurity, apparent life-threatening events of infancy and sudden infant death syndrome, awaits further studies., (2010 Elsevier Ltd. All rights reserved.)

During phonation, energy is transferred from the subglottal airflow through the air/mucosa interface that results in the propagation of the mucosal wave in the vocal fold. The vocal fold is soft, and the subglottal mucosa is stiff. We hypothesize that it is highly improbable that there is a rigid boundary between the tissue structures, with a sudden drop in stiffness; and that a gradual change would be more likely to support the efficient transfer of energy from the airflow to the mucosal wave. Our objective was to test this hypothesis by quantifying the change in mucosa stiffness with respect to anatomical position. In this initial study, using five pig larynges, a series of point-specific measurements of mucosa stiffness were taken in a line from the midpoint of the vocal fold toward the trachea. A modified linear skin rheometer adapted for laryngeal elasticity measurement applied shear stress to a series of seven positions at 2-mm intervals starting from the midmembranous vocal fold medial surface. A sinusoidal shear force of 1g was applied at each point, and resultant displacement curve logged. Using a regression algorithm, the stiffness of the tissue was derived in units of grams force per millimeter displacement. Five readings were taken at each position. The results indicate that there is a linear increase in stiffness with respect to position, increasing as the measurements are taken further from the vocal fold. There is a gradual change in stiffness of the subglottal mucosa of a pig larynx., ((c) 2010 The Voice Foundation. Published by Mosby, Inc. All rights reserved.)

The human vocal fold is treated as a continuous, transversally isotropic, porous solid saturated with liquid. A set of mathematical equations, based on the theory of fluid-saturated porous solids, is developed to formulate the vibration of the vocal fold tissue. As the fluid-saturated porous tissue model degenerates to the continuous elastic tissue model when the relative movement of liquid in the porous tissue is ignored, it can be considered a more general description of vocal fold tissue than the continuous, elastic model. Using the fluid-saturated porous tissue model, the vibration of a bunch of one-dimensional fibers in the vocal fold is analytically solved based on the small-amplitude assumption. It is found that the vibration of the tissue will lead to the accumulation of excess liquid in the midmembranous vocal fold. The degree of liquid accumulation is positively proportional to the vibratory amplitude and frequency. The correspondence between the liquid distribution predicted by the porous tissue theory and the location of vocal nodules observed in clinical practice, provides theoretical evidence for the liquid accumulation hypothesis of vocal nodule formation (Jiang, Ph.D., dissertation, 1991, University of Iowa)., ((c) 2010 The Voice Foundation. Published by Mosby, Inc. All rights reserved.)

Objectives/hypothesis: The purpose of this study was to examine the functional biomechanical properties of several injectable biomaterials currently or potentially used for vocal fold augmentation., Study Design: Rheometric investigation of phonosurgical materials in vitro., Methods: Linear viscoelastic shear properties of 3% bovine collagen (atelocollagen), micronized AlloDerm (Cymetra; LifeCell Corp., Branchburg, NJ), calcium hydroxylapatite (CaHA) (Radiesse; BioForm Medical, San Mateo, CA), and 2.4% cross-linked hyaluronic acid (HA) gel (Juvéderm; Allergan, Inc., Irvine, CA) were quantified as functions of frequency covering the phonatory range, and compared to those of the human vocal fold cover. Measurements of elastic shear modulus (G') and dynamic viscosity (eta') were made at up to 250 Hz with a controlled-strain simple-shear rheometer. Linear least-squares regression was conducted to curve-fit log G' and log eta' versus log frequency, and statistical analysis was performed with one-way analysis of variance., Results: Radiesse and Cymetra were found to be the stiffest and the most viscous materials, followed by Juvéderm and atelocollagen. There were significant differences in the magnitudes of G' and eta' among the phonosurgical materials and the normal human vocal fold cover (p < .001), whereas there was no significant difference in the frequency dependence of G' and eta' among the materials. Post hoc Tukey tests revealed significant differences (p < .05) in pairwise comparisons of the magnitudes of G' and eta' among all materials and the vocal fold cover., Conclusions: These findings suggested that although these biomaterials may be injected lateral to the lamina propria for the treatment of glottic insufficiency, none of them are rheologically optimal for the functional reconstruction of the vocal fold lamina propria.

Laryngopharyngeal reflux is commonly encountered in the ENT out-patient setting. It leads to impaired sensory capacity of the laryngeal mucosa. The sensory integrity of the laryngopharynx can be evaluated through endoscopic administration of pulsed air, which stimulates the laryngeal adductor reflex. The pressure of air needed to elicit this reflex indicates the degree of sensory impairment. Such laryngeal sensory testing gives a quantifiable means of assessment in patients with laryngopharyngeal reflux, and can be used to measure the response to treatment. Laryngeal sensory testing is safe and well tolerated by patients.

Adenovirus infection can cause various illnesses depending on the infecting serotype, such as gastroenteritis, conjunctivitis, cystitis, and rash illness, but the infection mechanism is still unknown. MicroRNAs (miRNA) have been reported to play essential roles in cell proliferation, cell differentiation, and pathogenesis of human diseases including viral infections. We analyzed the miRNA expression profiles from adenovirus type 3 (AD3) infected Human laryngeal epithelial (Hep2) cells using a SOLiD deep sequencing. 492 precursor miRNAs were identified in the AD3 infected Hep2 cells, and 540 precursor miRNAs were identified in the control. A total of 44 miRNAs demonstrated high expression and 36 miRNAs showed lower expression in the AD3 infected cells than control. The biogenesis of miRNAs has been analyzed, and some of the SOLiD results were confirmed by Quantitative PCR analysis. The present studies may provide a useful clue for the biological function research into AD3 infection.

Vocal fold surface liquid homeostasis contributes to optimal vocal physiology. In this paper we review emerging evidence that vocal fold surface liquid is maintained in part by salt and water fluxes across the epithelium. Based on recent immunolocalization and electrophysiological findings, we describe a transcellular pathway as one mechanism for regulating superficial vocal fold hydration. We propose that the pathway includes the sodium-potassium pump, sodium-potassium-chloride cotransporter, epithelial sodium channels, cystic fibrosis transmembrane regulator chloride channels, and aquaporin water channels. By integrating knowledge of the regulating mechanisms underlying ion and fluid transport with observations from hydration challenges and treatments using in vitro and in vivo studies, we provide a theoretical basis for understanding how environmental and behavioral challenges and clinical interventions may modify vocal fold surface liquid composition. We present converging evidence that clinical protocols directed at facilitating vocal fold epithelial ion and fluid transport may benefit healthy speakers, those with voice disorders, and those at risk for voice disorders.

A chain model was proposed in this study to examine the effects of mucosal loading on vocal fold vibration. Mucosal loading was defined as the loading caused by the interaction between the vocal folds and the surrounding tissue. In the proposed model, the vocal folds and the surrounding tissue were represented by a series of oscillators connected by a coupling spring. The lumped masses, springs, and dampers of the oscillators modeled the tissue properties of mass, stiffness, and viscosity, respectively. The coupling spring exemplified the tissue interactions. By numerically solving this chain model, the effects of mucosal loading on the phonation threshold pressure, phonation instability pressure, and energy distribution in a voice production system were studied. It was found that when mucosal loading is small, phonation threshold pressure increases with the damping constant R(r), the mass constant R(m), and the coupling constant R(mu) of mucosal loading but decreases with the stiffness constant R(k). Phonation instability pressure is also related to mucosal loading. It was found that phonation instability pressure increases with the coupling constant R(mu) but decreases with the stiffness constant R(k) of mucosal loading. Therefore, it was concluded that mucosal loading directly affects voice production.

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(-) channels are present in vocal fold epithelial cells and that transepithelial Cl(-) fluxes can be manipulated pharmacologically., Method: Immunohistochemical assays were used to identify cystic fibrosis transmembrane regulator Cl(-) channels in ovine vocal fold mucosae (n = 2). Electrophysiological responses of vocal fold mucosae (n = 80) to Cl(-) 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(-) transport inhibitor, diphenylamine-2-carboxylate, elicited a 30% decrease in mean short-circuit current (I(sc); n = 10). The secretagogue, isobutylmethylxanthine, yielded a 31.7% increase in mean I(sc) (n = 10). Another secretagogue, uridine triphosphate, elicited a 48.8% immediate and 17.3% sustained increase in mean I(sc) (n = 10). No sustained increases occurred following application of secretagogues to mucosae bathed in a low Cl(-) environment (n = 10), suggesting that responses were Cl(-) dependent., Conclusions: The authors provide structural and functional evidence for the presence of a transepithelial pathway for Cl(-) fluxes. Pharmacological manipulation of this pathway may offer a mechanism for maintaining superficial vocal fold hydration.

Vocal fold injury commonly leads to reduced vocal quality due to scarring-induced alterations in matrix composition and tissue biomechanics. The long-term hypothesis motivating our work is that rapid restoration of phonation and the associated dynamic mechanical environment will reduce scarring and promote regenerative healing. Toward this end, the objective of this study was to develop mechanomimetic, degradable hydrogels approximating the viscoelastic properties of the vocal ligament and mucosa that may be photopolymerized in situ to restore structural integrity to vocal fold tissues. The tensile and rheological properties of hydrogels (targeting the vocal ligament and mucosa, respectively) were varied as a function of macromer concentration. PEG diacrylate-based hydrogels exhibited linear stress-strain response and elastic modulus consistent with the properties of the vocal ligament at low strains (0-15%), but did not replicate the non-linear behavior observed in native tissue at higher strains. Methacrylated hyaluronic acid hydrogels displayed dynamic viscosity consistent with native vocal mucosa, while elastic shear moduli values were several-fold higher. Cell culture studies indicated that both hydrogels supported spreading, proliferation and collagen/proteoglycan matrix deposition by encapsulated fibroblasts throughout the 3D network.

Previous studies reporting the linear viscoelastic shear properties of the human vocal fold cover or mucosa have been based on torsional rheometry, with measurements limited to low audio frequencies, up to around 80 Hz. This paper describes the design and validation of a custom-built, controlled-strain, linear, simple-shear rheometer system capable of direct empirical measurements of viscoelastic shear properties at phonatory frequencies. A tissue specimen was subjected to simple shear between two parallel, rigid acrylic plates, with a linear motor creating a translational sinusoidal displacement of the specimen via the upper plate, and the lower plate transmitting the harmonic shear force resulting from the viscoelastic response of the specimen. The displacement of the specimen was measured by a linear variable differential transformer whereas the shear force was detected by a piezoelectric transducer. The frequency response characteristics of these system components were assessed by vibration experiments with accelerometers. Measurements of the viscoelastic shear moduli (G' and G") of a standard ANSI S2.21 polyurethane material and those of human vocal fold cover specimens were made, along with estimation of the system signal and noise levels. Preliminary results showed that the rheometer can provide valid and reliable rheometric data of vocal fold lamina propria specimens at frequencies of up to around 250 Hz, well into the phonatory range.

Objective/hypothesis: Vocal fold vibration is associated with four distinct vibratory patterns: those of the right-upper, right-lower, left-upper, and left-lower vocal fold lips. The purpose of this study was to propose a least squares method to quantify the vibratory properties of each of the four vocal fold lips via videokymography (VKG)., Study Design: This was a methodological study designed to examine the impact of subglottal pressure and line-scan position on mucosal wave parameters., Methods: VKG, a line-scan imaging technique, has proven to be an effective method for studying vocal fold vibratory patterns. This study used VKG images and an automatic mucosal wave extraction method to examine the vibration of each individual vocal fold lip of 17 excised canine larynges under differing subglottal pressures and line-scan positions., Results: Varying subglottal pressure led to results consistent with previous studies. Examination of the vocal folds at different line-scan positions along its length revealed that amplitude is greatest at the midpoint of the vocal fold, followed by the anterior portion of the vocal fold, with the posterior portion having the lowest amplitude (P < .001). Frequency and phase delay did not change significantly throughout the length of the vocal fold., Conclusions: The method used in this study allows for easy determination of four sets of vibratory parameters, and examination of the effect of biomechanical parameters on vocal fold vibrations.

The objective of this study was to investigate the underlying laryngeal mechanisms during the specific human 4-kHz vocalization. The laryngeal configuration during this vocalization was measured using high-resolution computerized tomographic scan and videostrobolaryngoscopy. The color Doppler imaging (CDI) of medical ultrasound was used to detect the vibrations of glottal and supraglottal mucosa. During the 4-kHz vocalization, the ventricular folds were adducted in the shape of a bimodal chink and the vocal folds were shaped as a "V" with an opening at the posterior glottis. In the coronal view, the laryngeal ventricles had collapsed and a divergent shaped conduit was observed at the posterior portion of the larynx. The surface mucosa vibration detected by CDI was noted over the bilateral ventricular folds and aryepiglottic folds. The vibration displacement was estimated to be on the order of 0.1mm. This vibration amplitude was too small to be detected in videostrobolaryngoscopy. The laryngeal configuration and CDI data suggested a diffuser jet with periodic vorticity bursts in the larynx producing 4 kHz voice.

The nonlinear viscoelastic passive properties of three canine intrinsic laryngeal muscles, the lateral cricoarytenoid (LCA), the posterior cricoarytenoid (PCA), and the interarytenoid (IA), were fit to the parameters of a modified Kelvin model. These properties were compared with those of the thyroarytenoid (TA) and cricothyroid (CT) muscles, as well as previously unpublished viscoelastic characteristics of the human vocal ligament. Passive parameters of the modified Kelvin model were summarized for the vocal ligament, mucosa, and all five laryngeal muscles. Results suggest that the LCA, PCA, and IA muscles are functionally different from the TA and CT muscles in their load-bearing capacity. Furthermore, the LCA, PCA, and IA have a much larger stress-strain hysteresis effect than has been previously reported for the TA and CT or the vocal ligament. The variation in this effect suggests that the connective tissue within the TA and CT muscles is somehow similar to the vocal ligament but different from the LCA, PCA, or IA muscles. Further demonstrating the potential significance of grouping tissues in the laryngeal system by functional groups in the laryngeal system was the unique finding that, over their working elongation range, the LCA and PCA were nearly as exponentially stiff as the vocal ligament. This paper was written in conjunction with an online technical report (http://www.ncvs.org/ncvs/library/tech) in which comprehensive muscle data and sensitivity analysis, as well as downloadable data files and computer scripts, are made available.

Objective: The linear skin rheometer (LSR), which measures skin visco-elasticity, was adapted for measurements of vocal fold properties. A series of studies was performed on animal and human excised larynges to determine if the LSR technique can be applied to the vocal fold., Methods: In excised larynges, small patches of mucosa were driven sinusoidally at 0.3 Hz over distances of 1-2 mm using a small probe. Forces in the order of 1 g equivalent gave optimal measurements. Stiffness and viscosity values were derived from stress/strain data., Results: The instrument was able to measure the visco-elasticity of the tissue in a repeatable manner and it could detect areas where the tissue was artificially stiffened. Two-dimensional maps of the mechanical properties of the laryngeal mucosa were obtained showing local variations in elasticity both parallel and perpendicular to the vocal fold edge. Initial studies were undertaken using animal tissue; more recently, the LSR has been successfully used to obtain similar data from human tissue., Conclusion: The LSR was been demonstrated to be capable of measuring the elastic properties of the vocal fold in a repeatable and reliable manner. Further studies will now be undertaken to obtain data from a larger sample of human tissue.

Repeated stimulation of the laryngeal mucosa occurs during speech. Single stimuli, however, can elicit the laryngeal adductor response (LAR). Our hypothesis was that the LAR to repeated rapid air pressure stimuli is centrally suppressed in humans. Hooked-wire electrodes were inserted into the thyroarytenoid and cricothyroid muscles on both sides and into the posterior cricoarytenoid muscle on one side. Pairs of air puff stimuli were presented to the mucosa over the arytenoids at pressure levels three times threshold with interstimulus intervals from 250 to 5,000 ms. Bilateral thyroarytenoid responses occurred at around 150 ms to more than 70% of the initial stimuli. With repeated presentation at intervals of 2 seconds or less, the percent occurrence decreased to less than 40% and response amplitudes were reduced by 50%. Central suppression of adductor responses to repeated air puff stimuli may allow speakers to produce voice without eliciting reflexive spasms that could disrupt speech.

Viscoelastic shear properties of human vocal fold tissues have been reported previously. However, data have only been obtained at very low frequencies (< or = 15 Hz). This necessitates data extrapolation to the frequency range of phonation based on constitutive modeling and time-temperature superposition. This study attempted to obtain empirical measurements at higher frequencies with the use of a controlled strain torsional rheometer, with a design of directly controlling input strain that introduced significantly smaller system inertial errors compared to controlled stress rheometry. Linear viscoelastic shear properties of the vocal fold mucosa (cover) from 17 canine larynges were quantified at frequencies of up to 50 Hz. Consistent with previous data, results showed that the elastic shear modulus (G'), viscous shear modulus (G"), and damping ratio (zeta) of the vocal fold mucosa were relatively constant across 0.016-50 Hz, whereas the dynamic viscosity (eta') decreased monotonically with frequency. Constitutive characterization of the empirical data by a quasilinear viscoelastic model and a statistical network model demonstrated trends of viscoelastic behavior at higher frequencies generally following those observed at lower frequencies. These findings supported the use of controlled strain rheometry for future investigations of the viscoelasticity of vocal fold tissues and phonosurgical biomaterials at phonatory frequencies.

Respiratory control in the fetus and neonate is quite immature when compared to that of adults. This immaturity involves all facets of respiration including respiratory responses to hypoxia, hypercapnia, an exaggerated apnoeic response to laryngeal stimulation and immature responses to activation of pulmonary afferents. The net result of this immaturity of breathing responses is the vulnerability of neonates and especially preterm infants to apnoea and respiratory pauses. The mechanisms behind immature control of breathing are not fully understood, but seem to originate from a predominance of inhibitory input early in life on respiratory centres. The relative contribution of up-regulation of inhibitory pathways versus down-regulation of excitatory ones is not clear. Multiple neurotransmitters have been implicated in the regulation of breathing in mammals and some of them are discussed in this chapter.

Objective: Under normal conditions, the vocal fold mucus layer is too thin to permit observation using videolaryngostroboscopy (VLS) during phonation. However, vocal nodules (VNs) typically cause congealed and sticky mucus to appear on the vocal fold. Reports in the literature regarding this phenomenon are limited. The aim of this study was to review VLS recordings of VN patients, analyzing changes that occurred in the mucus layer that covers the vocal fold during vibration following VN surgery., Material and Methods: Using VLS, we studied the occurrence of, and changes in, vocal fold mucus layers in 160 VN patients before and after surgery., Results: Eighty-eight patients (55%) were found to have a mucus layer during preoperative examinations. Of these mucus layers, 21 (13%) were located on the anterior commissure or anterior third of the vocal fold (A), 58 (36.3%) on the junction of the anterior and middle thirds (M), 1 (0.6%) on the posterior third (P), 5 (3.1%) on both A and M and 3 (1.9%) on both M and P. Fifty-six (35%) cases were found to have a mucus layer during postoperative examinations. Of these, 44 (27.5%) were located on A, 8 (5%) on M, 1 (0.6%) on P and 3 (1.9%) on both A and M. These results indicate that changes in the mechanical force on the vocal fold, alteration of the laryngeal secretory gland and improper aerodynamic airflow result in increased mucus viscosity and aggregation in VN patients and that the combination of these factors further increases the severity of dysphonia., Conclusions: Surgery to remove vocal nodes may be an effective method to eliminate both vocal bumps and aggregated mucus. Based on the present results, it is recommended that future research should compare surgery to remove VN against other mucus layer reduction methods in order to determine which is the most effective.

Numerous clinical findings indicate that viscosity of laryngeal mucosa is a crucial factor in glottal perfomance. Experience using experimental test benches has shown the importance of humidifying air stream used to induce vibration in excised larynges. Nevertheless, there is a lack of knowledge particularly regarding the physicochemical properties of laryngeal mucus. The purpose of this study was to research vocal fold vibration in excised larynges using artificial mucus of precisely known viscosity. Eight freshly harvested porcine larynges were examined. Parameters measured were Fo and vocal fold contact time. Measurements were performed under three conditions: basal (no fluid application on vocal cord surface), after application of a fluid of 60cP viscosity (Visc60), and after application of a fluid of 100cP viscosity (Visc100). Electroglottographic measurements were performed at two different times for each condition: 1 s after airflow onset (T1) and 6 seconds after airflow onset (T2). Statistical analysis consisted of comparing data obtained under each condition at T1 and T2. The results showed a significant decrease in Fo after application of Visc60 and Visc100 fluids and a decrease in Fo at T2. Closure time was significantly higher under Visc60 conditions and under Visc100 conditions than under basal conditions. Application of artificial mucus to the mucosa of the vocal folds lowered vibratory frequency and prolonged the contact phase. Our interpretation of this data is that the presence of mucus on the surface of the vocal folds generated superficial tension and caused adhesion, which is a source of nonlinearity in vocal vibration.

We conducted a retrospective study to analyze the videostroboscopic findings in a group of 21 patients who underwent vertical frontolateral laryngectomy with reconstruction by use of the sternohyoid muscle flap. They had T1b and T2 glottic tumors and a follow-up of more than 1 year. Three observers analyzed the recorded videostroboscopic data. The cases in which the stroboscopic evaluation of the vocal folds was incomplete were studied in regard to the clinical staging, the supraglottic hyperfunction, and the vibratory site; the Fisher exact test was applied. The glottic closure was complete in 15 individuals, and 6 had irregular vocal gaps. The site of vibration was glottic in 10 cases, supraglottic in 7, and mixed in 4. The amplitude was normal on 4 and slightly diminished on 9 preserved sides, whereas it was moderately or severely diminished on 16 and absent on 5 reconstructed sides. The mucosal wave vibratory pattern was always totally present on 15 preserved and 5 reconstructed sides: normal or slightly diminished in the preserved vocal folds, and moderately or severely diminished in the reconstructed ones. The reconstructed vocal folds had a nonvibrating portion in 5 cases. The movement extent of the preserved side was larger than that of the other side in 8 cases, and the sides were similar in 13 cases. The symmetry was regular in 18 cases. The periodicity was always or generally regular in 9 cases. There was supraglottic hyperadduction in 16 cases, with a lateral constriction predominance. The mucosal appearance was normal in 15 patients and wet in 6 patients. The epiglottis was straight in 14 cases and crescent in 7. Mucus formation was observed in 1 patient in the posterior vibratory portion. Videolaryngostroboscopy allowed thorough evaluation of the vibratory pattern of the vocal folds in 52.4% of the patients. The supraglottic hyperadduction component and the supraglottic vocal source presented difficulty for this evaluation. The site of vibration was glottic in 47.6%, supraglottic in 33.3%, and mixed in 19.1% of the cases. The vibratory pattern was diminished on both sides, but mainly on the reconstructed one.

Stimulation of laryngeal receptors is the natural starting point of defensive airway reflexes including the cough reflex, expiration reflex, spasmodic panting, and apnoea with laryngospasm. Although several different types of laryngeal receptors have been reported, the laryngeal irritant receptors are considered to play the most essential role in elicitation of defensive airway reflexes. Based on the knowledge that the laryngeal irritant receptors are stimulated by water solutions lacking chloride anions, we have developed an experimental method to elicit defensive airway reflexes with a direct instillation of distilled water onto the laryngeal mucosa in humans. Using this experimental method, we studied the characteristics of defensive airway reflexes in lightly anaesthetized patients with multiple system atrophy (MSA). The reflex responses to water stimulation observed in these patients were characterized by apnoea with laryngospasm while the cough reflex was never elicited. Endoscopic images of the larynx in these patients were also characterized by laryngeal oedema. Considering the pathological changes occurring in the central nervous system and the laryngeal mucosa, it is possible that the defensive airway reflexes may be modified by central and/or peripheral mechanisms in patients with MSA.

Vocal folds undergo osmotic challenge by mouth breathing during singing, exercising, and loud speaking. Just 15 min of obligatory oral breathing, to dry the vocal folds, increases phonation threshold pressure (Pth) and expiratory vocal effort in healthy speakers (M. Sivasankar & K. Fisher, 2002). We questioned whether oral breathing is more detrimental to phonation in healthy participants with a history of temporary vocal attrition. The effects of a 15-min oral or nasal breathing challenge on Pth and perceived expiratory vocal effort were compared for participants reporting symptoms of vocal attrition (N = 18, ages 19-38 years) and normal controls (N = 20, ages 19-33 years). Post-challenge-prechallenge differences in Pth (deltaPth) and effort (deltaEffort) revealed that oral breathing, but not nasal breathing, increased Pth (p < .001 ) and effort (p < .001) at low, comfortable, and high pitch. deltaPth was significantly greater in participants with vocal attrition than in normal controls (p < .001). Nasal breathing reduced Pth for all controls but not for all participants reporting vocal attrition. deltaPth was significantly and linearly correlated with deltaEffort (rvocal attrition = .81, p < .001; rcontrol = .84, p < .001). We speculate that the greater increases in Pth in participants reporting vocal attrition may result from delayed or inadequate compensatory response to superficial laryngeal dehydration. Obligatory oral breathing may place voice users at risk for exacerbating vocal attrition. That sol layer depletion by obligatory oral breathing increased Pth and vocal effort provides support for the role of superficial hydration in maintaining ease of phonation.

Objectives: This investigation compared speech and deglutition functions after alternative surgical treatments for advanced stage laryngeal carcinoma: the supracricoid laryngectomy (SCL) versus the total laryngectomy (TL). Study design and setting Cohort investigation at Wayne State University School of Medicine., Methods: Quantitative studies of laryngeal biomechanics, acoustic and speech aerodynamic features, and deglutition skills of these individuals were coupled to listener and patient self-impressions of speech and voice characteristics for group comparative analyses., Results: Results revealed that patients from each subgroup performed comparably relative to speech intelligibility and voice quality disturbances. Videostroboscopy of the neoglottal mechanisms in these two populations helped to explain these outcomes. Acoustic and speech aerodynamic testing demonstrated variably abnormal features in both surgical subgroups. Whereas the SCL patients eventually achieved full oral diets, they required many sessions of swallowing therapy to obtain this objective and eliminate tube feeding supplementation. The TL patients did not evidence protracted swallowing difficulties or the need for specific exercises in order to remove their feeding tubes postoperatively. References to organ preservation strategies in lieu of surgical management are included for completeness purposes., Conclusions: The SCL and TL surgical procedures for advanced stage laryngeal carcinoma resulted in equivalent speech and swallowing functional outcomes.

The mucosal waves on the vibrating vocal folds may move in anterior-posterior, mediolateral and in caudal-cranial direction. This article discusses the possible significance of the vertical movement from the point of view of mechanical stress in phonation and the formation of vocal fold traumas. It is hypothesized that in certain conditions the vocal folds may behave in cranial direction like a quasi-free end of a long lash producing very rapid vibratory waves (e.g. the waves in a whiplash). This could be detrimental to the tissue structure. The role of phonation type in enhancing/diminishing this effect will also be discussed., (Copyright 2003 S. Karger AG, Basel)

We tested the hypothesis that mucosal pressures are higher for the laryngeal tube airway trade mark than the ProSeal laryngeal mask airway. Fifteen fresh cadavers were studied. Microchip pressure sensors were attached to the laryngeal tube airway and ProSeal laryngeal mask airway at four similar anatomical locations (base of tongue, lateral pharynx, posterior pharynx and posterior hypopharynx) and three dissimilar locations (laryngeal tube airway trade mark, anterior and lateral hypopharynx; ProSeal laryngeal mask airway, pyriform fossa). The cuff volume (laryngeal tube airway, < or = 140 ml; ProSeal laryngeal mask airway, < or = 30 ml) was adjusted until the oropharyngeal leak pressure was 15 cm H2O and the mucosal pressures recorded. This was repeated at an oropharyngeal leak pressure of 20, 25 and 30 cm H2O. Mucosal pressures in the lateral pharynx were always similar. Mucosal pressures at the base of tongue and posterior pharynx were similar for the laryngeal tube airway and ProSeal laryngeal mask airway at 15 and 20 cm H2O, but were higher for the laryngeal tube airway at 25 cm H2O at 30 cm H2O. Mucosal pressures in the posterior hypopharynx were always higher for the laryngeal tube airway (all: p < 0.03). Mean mucosal pressures for the laryngeal tube airway ranged from 8-31, 2-13 and 15-41 cm H2O for the base of tongue, lateral pharynx and posterior pharynx (proximal cuff) respectively and 3-7, 3-7 and 7-18 cm H2O for the anterior, lateral and posterior hypopharynx (distal cuff) respectively. Mean mucosal pressures for the ProSeal laryngeal mask airway ranged from 6-23, 3-10, 8-25, 6-17 and 2-8 cm H2O for the base of tongue, lateral pharynx, posterior pharynx, pyriform fossa and posterior hypopharynx respectively. We conclude that mucosal pressures are higher for the laryngeal tube airway, particularly when oropharyngeal leak pressure greater than 25 cm H2O. This suggests that mucosal ischemic injury will be more common with the LTA than the PLMA.

It is common practice in laryngeal research laboratories to store excised larynges and vocal fold tissue specimens frozen, presumably to preserve viability and structural integrity of the specimens for physiologic and biomechanical experiments. However, little is known about the biomechanical effects of postmortem changes and frozen storage in vocal fold tissues. This study attempted to quantify the effects of postmortem changes and freezing on the viscoelastic shear properties of the canine vocal fold mucosa. Sixteen larynges were excised from adult dogs immediately postmortem in a viable state. Using a torsional rheometer, the complex shear modulus (G*) of the mucosal tissue from one vocal fold of each larynx was measured as a function of frequency (0.01-15 Hz) by linear small-amplitude oscillation experiments. Measurement was repeated for ten mucosal specimens after 24 h of postmortem storage in saline solution at room temperature. Eleven of the 16 larynges were frozen and stored at -20 degrees C, six of them at a slow rate of cooling (storage in a regular freezer) and five others by quick freezing (chilling by liquid nitrogen prior to frozen storage). The larynges were thawed slowly overnight after one month and the viscoelastic shear properties of the contralateral vocal fold mucosa were measured. Results showed that the elastic shear modulus (G') and dynamic viscosity (eta') of the vocal fold mucosa did not seem to change significantly after 24 h of storage in saline at room temperature, nor after one month of frozen storage following quick freezing, whereas both G' and eta' decreased significantly for tissues that were slowly frozen. These findings supported the feasibility of using quick freezing to preserve laryngeal tissues for in vitro biomechanical testing, for excised larynx experiments, and for tissue engineering applications.

Objective: Anecdotally, it has been observed that in some healthy middle-aged men, who have neither vocal complaints nor known vocal pathology, asymmetries of the mucosal wave exist when examined videostroboscopically. This may cause concern on the part of the otolaryngologist, who might consider mucosal wave asymmetries to be a forewarning of subclinical pathology and subject the patient to unnecessary, expensive, and anxiety-provoking investigations or interventions. The purpose of this study is to establish the presence of mucosal wave asymmetries in a healthy, asymptomatic subpopulation. Acoustic spectral analysis is also used to determine if the presence of subharmonics might be associated., Study Design: A prospective, cohort study design was used. The population was randomly selected, healthy, asymptomatic, nonsmoking men aged 35 to 50 years. Each subject completed acoustic spectral analysis and a medical questionnaire, followed by videostroboscopic laryngeal examination., Results: Thirty-seven percent of the subjects exhibited mucosal wave variations at stroboscopy, characterized as periodic lateral phase asymmetries. There was no association with the acoustic spectral parameters chosen., Conclusion: Mucosal wave asymmetries may be a variance of normal. The 37% found here is expected to be very significant. Mucosal wave asymmetries are likely to be far more common in the general population than previously believed. There have been few normative data published for variations of the mucosal wave specifically for epidemiologic purposes. These results establish a starting point and justification for the normative population studies under way at our institution. Clinically, in the absence of such data, otolaryngologists may overinterpret videostroboscopic findings, leading to unnecessary investigations or interventions.

Background: The authors determined the influence of cuff volume and anatomic location on pharyngeal, esophageal, and tracheal mucosal pressures for the esophageal tracheal combitube., Methods: Twenty fresh cadavers were studied. Microchip sensors were attached to the anterior, lateral, and posterior surfaces of the distal and proximal cuffs of the small adult esophageal tracheal combitube. Mucosal pressure for the proximal cuff in the pharynx was measured at 0- to 100-ml cuff volume in 10-ml increments, and for the distal cuff in the esophagus and trachea were measured at 0- to 20-ml cuff volume in 2-ml increments. The proximal cuff volume to form an oropharyngeal seal of 30 cm H2O was determined. In addition, mucosal pressures for the proximal cuff in the pharynx were measured in four awake volunteers with topical anesthesia., Results: There was an increase in mucosal pressure in the trachea, esophagus, and pharynx at all cuff locations with increasing volume (all: P < 0.001). Pharyngeal mucosal pressures were highest posteriorly (50-ml cuff volume: 99 +/- 62 cm H2O; 100-ml cuff volume: 255 +/- 161 cm H2O). Esophageal mucosal pressures were highest posteriorly (10-ml cuff volume: 108 +/- 55 cm H2O; 20-ml cuff volume: 269 +/- 133 cm H2O). Tracheal mucosal pressures were highest anteriorly (10-ml cuff volume: 98 +/- 53 cm H2O; 20-ml cuff volume: 236 +/- 139 cm H2O). The proximal cuff volume to obtain an oropharyngeal seal of 30 cm H2O was 47 +/- 12 ml. Pharyngeal mucosal pressures were similar for cadavers and awake volunteers., Conclusion: We conclude that mucosal pressures for the esophageal tracheal combitube increase with cuff volume, are highest where the cuff is adjacent to rigid anatomic structures, and potentially exceed mucosal perfusion pressure even when cuff volumes are limited to achieving an oropharyngeal seal of 30 cm H2O.