Vocal Fold Morphology Research Articles

Laryngopharyngeal reflux leads to adverse short-term outcomes of vocal fold polyp patients after office-based transnasal vocal fold polypectomy.

This study aimed to explore the influence of laryngopharyngeal reflux on the features of vocal fold polyps and prognosis after office-based transnasal vocal fold polypectomy. Eighty-four vocal fold polyp patients were retrospectively analysed. Patients were assigned to laryngopharyngeal reflux or non-laryngopharyngeal reflux groups using pre-operative Reflux Symptom Score-12. The laryngopharyngeal reflux group had significantly higher pre-operative Reflux Sign Assessment scores, worse lifestyle and worse eating habits than the non-laryngopharyngeal reflux group. After office-based transnasal vocal fold polypectomy, the Reflux Symptom Score-12 and Reflux Sign Assessment score decreased in both groups, although the laryngopharyngeal reflux group still had higher values. The non-laryngopharyngeal reflux group had better vocal fold morphology recovery than the laryngopharyngeal reflux group. Multivariate logistic regression analysis demonstrated that smoking and a higher pre-operative Reflux Symptom Score-12 score were independent risk factors for poor prognosis. Laryngopharyngeal reflux is detrimental to vocal fold recovery of vocal fold polyp patients following office-based transnasal vocal fold polypectomy. For vocal fold polyp patients with laryngopharyngeal reflux, lifestyle and diet guidance should be focused.

Quantitative Evaluation of Vocal Bowing Following Bilateral Thyroplasty in Age-Related Vocal Atrophy.

Age-related vocal atrophy (ARVA) is associated with vocal fold bowing, persistent glottal gap during phonation, and dysphonia. Bilateral medialization thyroplasty is sometimes performed in patients with ARVA to improve vocal fold closure and voice. We set out to quantify stroboscopic changes in vocal fold bowing, glottal closure, and abduction angle following bilateral thyroplasty and determine how these changes affect voice quality among patients with ARVA. Fifteen individuals with ARVA who underwent bilateral medialization thyroplasty were included in this study. Two independent investigators calculated bowing index (BI), normalized glottal gap area (NGGA), and maximum abduction angle from laryngostroboscopic exams using ImageJ™. Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V) and patient-reported measures were collected before and after thyroplasty. Thyroplasty resulted in a 10-point improvement in overall CAPE-V (Mean dif -10; 95% CI -17, -3.3, p < 0.01) and VHI-10 (mean dif -3.8; 95% CI -9.8, 2.3, p = 0.19, n = 8). NGGA and BI significantly decreased following surgery (mean dif -78; 95% CI -155, -1.5, p = 0.05; and mean dif -2.1; 95% CI -2.4, -0.84, p < 0.01, respectively). BI correlated with CAPE-V scores (r = 0.66, 95% CI 0.22, 0.87, p < 0.01). When considering the normalized combined contributions of both NGGA and BI, there was a stronger correlation in CAPE-V scores (r = 0.87, 95% CI 0.50, 0.97, p < 0.01) compared with either measure alone. Thyroplasty resulted in a decrease in vocal fold bowing, glottal gap area, and CAPE-V scores in patients with ARVA. Correction of vocal bowing and glottal gap, following bilateral thyroplasty, improved voice measures following surgery. Quantitative evaluation of vocal fold morphology may be valuable when assessing the severity and treatment-response in patients with ARVA following bilateral thyroplasty. Laryngoscope, 134:835-841, 2024.

Normative data for certain vocal fold biomarkers among young normophonic adults using ultrasonography

PurposeThe current study aimed to profile vocal fold morphology, vocal fold symmetry, gender and task-specific data for vocal fold length (VFL) and vocal fold displacement velocity (VFDV) in young normophonic adults in the age range of 18–30 years using ultrasonography (USG).MethodsParticipants underwent USG across quiet breathing, /a/ phonation and /i/ phonation tasks, and acoustic analysis was conducted to explore the relationship between USG and acoustic measures.ResultsThe study found that males have longer vocal folds than females, and overall greater velocities were observed in /a/ phonation, followed by /i/ phonation, with the lowest velocity observed in the quiet breathing task.ConclusionsThe obtained norms can be used as a quantitative benchmark for analyzing the vocal fold behavior in young adults.

Gender in human phonation: Fluid–structure interaction and vocal fold morphology

This paper aims to examine the effects of variations in the vocal fold (VF) morphological features associated with gender on glottal aerodynamics and tissue deformation. Nine three-dimensional geometries of the VFs in the larynx are created with various VF lengths, thicknesses, and depths to perform a parametric analysis according to gender-related geometrical parameters. The computational model is incorporated in a fluid–structure interaction methodology by adopting the transient Navier–Stokes equations to model airflow through the larynx and considering a linear elasticity model for VF dynamics. The model predictions, such as aerodynamic data through the larynx, glottal airflow, and VF deformations, are analyzed. The comparison of the simulation results for the nine cases supports the hypothesis that gender differences in laryngeal dimensions remarkably influence the glottal airflow and deformation of the VFs. Decreasing VF thickness and increasing its length corresponds to a noticeable increase in maximum tissue displacement, while variations in depth affect the flow rate significantly in the small and large larynges. Conversely, we observed that the pressure drop at the glottis is nearly independent of the VF length. A comparison of the glottal area with published imaging data illustrated a direct correlation between the glottal configuration and the morphology of the VFs.

Effect of Controlled Muscle Activation in a Unilateral Vocal Fold Polyp Setting on Vocal Fold Vibration

Unilateral vocal fold polyps can lead to incomplete glottal closure and irregular vocal fold vibration. Depending on polyp size and resulting dysphonia severity, voice therapy or surgery may be recommended. As part of voice therapy, patients may learn how to optimize intrinsic and extrinsic laryngeal muscle use to mitigate benign lesion effects, increase vocal efficiency, and improve voice quality. In this study, we used a low-dimensional mass model with a simulated unilateral vocal fold polyp and varied intra-laryngeal muscle activity to simulate vocal fold vibration across varied conditions. Differing muscle activation has different effects on frequency, periodicity, and intensity. Accordingly, learning how to optimize muscle activity in a unilateral polyp setting may help patients achieve the best possible periodic and most efficiently produced voice in the context of abnormal vocal fold morphology.

Globus Sensation And Retching In A 21-year-old Male Football Player.

HISTORY: 21 year old male football player presents with a tightness in his throat and dry heaving during football activity. He had similar symptoms 4 years ago that resurfaced 5 months ago without inciting event. Symptoms occur with strenuous activity on the field and cause a sensation of throat tightness that makes him want to vomit. He immediately loses focus on the game when symptoms occur, negatively affecting his performance. Denies stridor, dysphagia, dysphonia, unsteady gait, history of psychological disorder or treatment. PHYSICAL EXAM: GEN: NAD, well-appearing. HEENT: Oropharynx clear, normal tongue protrusion and palate elevation. Neck: No lymphadenopathy, no thyromegaly. CV: RRR, no murmur. Lungs: CTAB.GI: Normal bowel sounds, nontender. NEURO: No focal deficits, CN II-XII grossly intact. PSYCH: Appropriate mood and affect. Appropriate insight and judgment. DIFFERENTIAL DIAGNOSIS: 1. GERD 2. Vocal cord dysfunction 3. Esophageal spasm 4. Exercise-induced bronchospasm 5. Anxiety disorder TEST AND RESULTS: Barium swallow study: Small transient sliding hiatal hernia. Laryngoscopy with stroboscopy: Mild edema of bilateral vocal cords. Normal vocal fold mobility and morphology bilaterally. Exercise bike test with fiberoptic laryngoscopy: No paradoxical motion of vocal cords at rest or with bike testing. No evidence of vocal cord dysfunction. Esophageal manometry: Normal manometry but ineffective esophageal motility with viscous/solid consistencies indicating minor disorder of esophageal motility not classifiable. FINAL/WORKING DIAGNOSIS: Mild esophageal spasm complicated by unspecified anxiety disorder. TREATMENT AND OUTCOMES: He was started on empiric PPI therapy, which was discontinued after one week given no response. He was referred to a sports psychologist and engaged in cognitive behavioral therapy including psychoeducation, cognitive restructuring, exposure therapy, and mindfulness training to assist with reduction of his physiological symptoms. He practiced swallowing exposures during physical exertion over 3 weeks. Following exposure therapy, he reported being able to distract himself and reduce his concern about the sensation. He had significant improvement in his symptoms and finished the season at a highly competitive level without any recurrence of episodes.

Correlation Between Detection Results of Pepsin in Vocal Fold Polyp Tissues and the Postoperative Efficacy

To explore the correlation between detection results of pepsin in vocal fold polyp tissues and the postoperative efficacy. The clinical data of 112 patients with vocal fold polyp who received surgical procedures in our hospital from June 2019 to March 2021 were retrospectively analyzed. The vocal fold morphology and vocal acoustic function were assessed at postoperative week 12. Using binary logistic regression, we explored whether the factors, ie, detection result of pepsin in vocal fold polyp tissue, microscopic suturing, the use of CO2 laser, and the history of smoking, affected the postoperative morphological repair of vocal fold polyps. Then, to observe and compare the influence of the detection results of pepsin on the recovery of vocal acoustic function, we divided the enrolled patients into the pepsin group and the pepsin-free group based on the postoperative detection results of pepsin in the polyp tissues by immunohistochemistry, RESULTS: In the 112 patients with vocal fold polyps, positive staining of pepsin in the postoperative samples was found in 76 patients (67.86%) and negative in 36 (32.14%). Totally 80 patients returned to normal in vocal fold morphology, among whom 32 (88.89%) were in pepsin-free group and 48 (63.16%) in pepsin group. Binary logistic regression showed that pepsin was a clinically significant indicator that affected the postoperative morphological recovery of the vocal fold (P = 0.003). Although hoarse voice was improved in all patients at postoperative week 12, the differences were statistically significant in the proportion of patients with grade, roughness, breathiness, asthenia, strain class G, voice handicap index, maximum phonation time, Jitter, Shimmer and noise-to-harmonic ratio between the pepsin group and the pepsin-free group (P < 0.05), with the pepsin-free group being superior to the pepsin group in the improvement of vocal acoustic function. Pepsin in vocal fold polyps is a clinically significant indicator affecting the postoperative morphological recovery and acoustic efficacy, and patients with negative pepsin are superior to those with positive pepsin in the postoperative recovery of vocal fold morphology and function.

Application of dynamic CT scan in the three-dimensional dynamic morphology changes of laryngeal soft tissue in unilateral vocal fold paralysis patients

Objective: To explore the dynamic changes of three-dimensional morphology of laryngeal soft tissue and its clinical value in the unilateral vocal fold paralysis (UVFP) patients through dynamic CT scanning during the process from inspiration to phonation. Methods: From October 2017 to July 2019, a retrospective study was performed in 18 patients with UVFP (10 males and 8 females with the range of age from 29 to 75 years old) and 10 normal subjects (5 males and 5 females with the range of age from 25 to 58 years old) in Department of Voice-Otolaryngology Head and Neck Surgery, Section Two, Zhongshan Hospital Xiamen University. The laryngeal dynamic computed tomography (CT) of cine mode was performed. Ten dynamic sequence images of vocal folds movements were obtained during the process from inspiration to phonation. Based on the dynamic changes of glottic area and the displacement of cricoid cartilage. The above dynamic sequence images were divided into inspiratory phase and phonation phase as well as open phase and closed phase. The soft tissue parameters were measured respectively, including vocal folds length, width, thickness and subglottal convergence angle. Independent-sample t test was used to analyze between UVFP group and control group. Results: During the process from inspiration to phonation, the morphology of vocal folds in control group was relatively stable at inspiratory phase and closed phase in phonation. When open phase and closed phase of phonation were switching, the morphology of vocal folds changed obviously. The length of vocal folds became longer (1.19±0.10) mm, the width became wider (2.19±0.17) mm, the thickness became thinner (2.66±0.56) mm, and the subglottal convergence angle decreased (31.45±4.78)°. Compared with the controll group, in the open phase, the thickness and width of the vocal fold on affected side in the UVFP group were thinner (t=10.25, P<0.001) and wider (t=5.25, P<0.001).While in the closed phase, the subglottal convergence angle was larger (t=4.41, P=0.001).The width of the healthy side vocal fold in the UVFP was wider (t=2.54, P=0.026) than that in the control group. The differences in other parameters were not statistically significant. Conclusions: Dynamic laryngeal CT scanning provides a simple and non-invasive method for the objective and quantitative measurement of the dynamic changes of laryngeal morphology from inspiration to phonation. Compared with the control group, the characteristic dynamic changes among UVFP were observed during this particular process, which included changes of subglottal convergence angle and thickness of vocal muscle due to denervation. In addition, in UVFP group, the width of the vocal fold healthy side in the closed phase may be used to assess its compensatory function.

Savannah roars: The vocal anatomy and the impressive rutting calls of male impala (Aepyceros melampus) - highlighting the acoustic correlates of a mobile larynx.

A retractable larynx and adaptations of the vocal folds in the males of several polygynous ruminants serve for the production of rutting calls that acoustically announce larger than actual body size to both rival males and potential female mates. Here, such features of the vocal tract and of the sound source are documented in another species. We investigated the vocal anatomy and laryngeal mobility including its acoustical effects during the rutting vocal display of free‐ranging male impala (Aepyceros melampus melampus) in Namibia. Male impala produced bouts of rutting calls (consisting of oral roars and interspersed explosive nasal snorts) in a low‐stretch posture while guarding a rutting territory or harem. For the duration of the roars, male impala retracted the larynx from its high resting position to a low mid‐neck position involving an extensible pharynx and a resilient connection between the hyoid apparatus and the larynx. Maximal larynx retraction was 108 mm based on estimates in video single frames. This was in good concordance with 91‐mm vocal tract elongation calculated on the basis of differences in formant dispersion between roar portions produced with the larynx still ascended and those produced with maximally retracted larynx. Judged by their morphological traits, the larynx‐retracting muscles of male impala are homologous to those of other larynx‐retracting ruminants. In contrast, the large and massive vocal keels are evolutionary novelties arising by fusion and linear arrangement of the arytenoid cartilage and the canonical vocal fold. These bulky and histologically complex vocal keels produced a low fundamental frequency of 50 Hz. Impala is another ruminant species in which the males are capable of larynx retraction. In addition, male impala vocal folds are spectacularly specialized compared with domestic bovids, allowing the production of impressive, low‐frequency roaring vocalizations as a significant part of their rutting behaviour. Our study expands knowledge on the evolutionary variation of vocal fold morphology in mammals, suggesting that the structure of the mammalian sound source is not always human‐like and should be considered in acoustic analysis and modelling.

Endoscopic Sealing With a Polyglycolic Acid Sheet for Restoration of Vocal Fold Mucosa in Dogs.

Voice outcomes of cordectomy for early glottic cancer are often poor due to vocal fold scarring and tissue defects. Improvements in this aspect could make cordectomy a more acceptable treatment option than radiotherapy. We hypothesized that a polyglycolic acid (PGA) sheet could be used to cover vocal fold defects. The present study aimed to prevent vocal fold scarring after cordectomy using the PGA sheet. Animal experiment. Nine male beagles were divided into three groups including a control group (n = 3). Following cordectomy, the vocal fold defect was covered with the PGA sheet plus fibrin glue (PGA group; n = 3) or with the PGA sheet plus fibrin glue containing basic fibroblast growth factor (bFGF; the PGA-bFGF group, n = 3). Vocal folds were chronologically observed, and larynges were removed 6 months after surgery. Mucosal amplitude was measured using a high-speed camera, and histological analysis was performed. The re-epithelialization process was delayed in the PGA and PGA-bFGF groups compared with the control group. The mucosal amplitude was significantly more normalized and the thickness ratio significantly higher in the PGA and PGA-bFGF groups compared with the control group. The PGA-bFGF group had the highest elastic fiber density, followed by the PGA group and then the control group, with a significant difference between the PGA-bFGF and control groups. The PGA sheet plus fibrin glue could serve as an effective regenerative scaffold for reconstructing vocal fold morphology and function after cordectomy, with the potential benefit of establishing an endoscopic sealing method for vocal fold defects. NA Laryngoscope, 130:E436-E443, 2020.

Synchronized, concurrent optical coherence tomography and videostroboscopy for monitoring vocal fold morphology and kinematics

Voice disorders affect a large number of adults in the United States, and their clinical evaluation heavily relies on laryngeal videostroboscopy, which captures the medial-lateral and anterior-posterior motion of the vocal folds using stroboscopic sampling. However, videostroboscopy does not provide direct visualization of the superior-inferior movement of the vocal folds, which yields important clinical insight. In this paper, we present a novel technology that complements videostroboscopic findings by adding the ability to image the coronal plane and visualize the superior-inferior movement of the vocal folds. The technology is based on optical coherence tomography, which is combined with videostroboscopy within the same endoscopic probe to provide spatially and temporally co-registered images of the mucosal wave motion, as well as vocal folds subsurface morphology. We demonstrate the capability of the rigid endoscopic probe, in a benchtop setting, to characterize the complex movement and subsurface structure of the aerodynamically driven excised larynx models within the 50 to 200 Hz phonation range. Our preliminary results encourage future development of this technology with the goal of its use for in vivo laryngeal imaging.

Dehydration and Estrous Staging in the Rat Larynx: an in vivo Prospective Investigation

This novel study sought to untangle the association between hydration state and the estrous cycle in the vocal folds, since the voice is reported to negatively change in speakers during the estrous cycle and with dehydration. We hypothesized that there would be alterations in vocal fold tissue morphology depending on hydration state and that these changes would vary with the estrous cycle. Prospective, in vivo study design. Female Sprague Dawley rats (n = 30) were used in this study. Sixteen rats were systemically dehydrated to an average of 10% reduction in body weight by withholding water (range of body weight loss: 8%-13%). Fourteen rats were assigned to euhydrated, control condition. Estrous stage of female Sprague Dawley rats (n = 30) was determined via cytological evaluation of vaginal smears. Following euthanization, larynges were prepared for histological staining with hematoxylin and eosin, Masson's trichrome and alcian blue (pH 2.5). To quantify hyaluronan, alcian blue staining was completed pre- and posthyaluronidase incubation. The change in staining percent was quantified with image analysis algorithms and reported as the hyaluronan quantity. Relative collagen distribution (index of dehydration), hyaluronan quantity, and tissue morphology were the outcome measures. Systemic dehydration was associated with changes in hyaluronan quantity in the rat vocal fold lamina propria. Dehydration did not significantly affect the collagen distribution nor the tissue morphology. Estrous stage alone does not impact the quantity of vocal fold hyaluronan, alter tissue morphology, or change collagen distribution. Decreases in hyaluronan quantity in the lamina propria of the rat vocal fold may play a role in tissue fluid balance during systemic dehydration. Future studies will expand this work to investigate additional components of the vocal fold extracellular matrix to fully elucidate the impact of hydration state on the vocal fold.

Evaluation of Voice Quality in Patients With Vocal Fold Polyps: The Size of a Polyp Matters or Does it?

ObjectiveThis study aimed to investigate the correlation between morphological features of vocal fold polyps (VFPs) and subjective/objective voice parameters. MethodsPerceptual evaluations, aerodynamic and acoustic tests were performed on 47 patients with VFPs. Still images were captured from video and the morphological features associated with the size of VFP were quantified. To reveal the correlation between size-related morphological features (length of polyp base, the ratio of polyp base to vocal fold length, glottal gap area) and objective/subjective parameters of voice, Pearson's and Spearman's tests were carried out. ResultsThis cohort was composed of 30 (63.8 %) male and 17 (36.2%) female patients with the mean age of 45.2 years and 41.3 years, respectively. No correlation was found between the morphological features of VFPs and any of perceptual, aerodynamic and acoustic voice parameters. ConclusionsOur findings indicated that controversies still exist regarding the role of vocal fold polyp morphology in clinical decision making.

Using intraoperative optical coherence tomography to image pediatric unilateral vocal fold paralysis

ObjectivesUnilateral vocal fold paralysis (UVFP) impairs communication and reduces academic performance and social interactions in children. Deciding between temporary, permanent, or potentially destructive surgical interventions can be challenging, as there currently exists no reliable means of predicting vocal fold recovery or assessing the presence of vocal fold atrophy. Regarding vocal fold atrophy, optical coherence tomography (OCT) has been shown to be an appealing non-invasive alternative for accessing vocal fold structures. This study describes UVFP microanatomy and identifies possible vocal fold atrophy using OCT. MethodsThree UVFP patients (ages 1, 11, and 17 years) underwent bilateral OCT imaging using a handheld probe while under general anesthesia for direct laryngoscopy, and the laryngoscopic images were compared with images obtained from OCT. Structural morphological features were extracted and compared to a healthy patients' cohort. ResultsWhile endoscopy showed no evidence of vocal fold atrophy in two of three cases, OCT images revealed distinct differences between the lamina propria of the paralyzed and functional vocal folds in all patients. In two cases, the paralyzed vocal fold morphology was similar to a healthy patient at the age of nerve injury. The third case exhibited extensive scarring in the lamina propria of the paralyzed vocal fold. ConclusionThis pilot study characterizes and compares vocal fold microanatomy in three UVFP patients. In most cases, lamina propria development halted at the age of paralysis, suggesting that lamina propria maturation may be dependent on vocal fold functionality. OCT shows potential to aid UVFP assessment and treatment decisions by evaluating the presence of atrophy.

Changes in Vocal Fold Morphology During Singing Over Two Octaves

ObjectiveVocal folds are widely assumed to only elongate to raise vocal pitch. However, the mechanisms seem to be more complex and involve both elongation and tensioning of the vocal folds in series. The aim of the present study was to show that changes in vocal fold morphology depend on vocal fold elongation and tensioning during singing. Study designThis was a prospective study. MethodsForty-nine professional female singers (25 sopranos, 24 altos) were recruited and three-dimensional laryngeal images analyzed in a coronal view derived from high-resolution computed tomography scans obtained at the mean speaking fundamental frequency (ƒ0) and one (2ƒ0) and two octaves (4ƒ0) above ƒ0. ResultsThe vocal fold angle, defined by a tangent above and below the vocal folds, was 58° at ƒ0, 47° at 2ƒ0, and 59° at 4ƒ0. ConclusionThe decreased caudomedial angle of the vocal fold from ƒ0 to 2ƒ0 (change in muscle belly from “;fat” to “thin”) and increased angle from 2ƒ0 to 4ƒ0 (from “thin” to “fat”) strongly supports the hypothesis that the vocal folds elongate and then tension when singing from ƒ0 to 4ƒ0. This is the first study to show this relationship in vivo.

Effect of saline inhalation on vocal fold epithelial morphology evaluated by optical coherence tomography.

Examination of tissue structures by optical coherence tomography (OCT) has been shown to be useful on mucous membranes of the vocal folds, but so far its application to the human larynx has been limited because it is technically cumbersome and usually needs to be performed with sedation. Here a newly developed, noninvasive combined laryngoscopy and OCT procedure is described and its suitability for ambulatory OCT studies evaluated. Because inhalation therapies utilizing saline solutions are commonly used as a treatment option for disorders of the airways, and vocal fold epithelium is most likely to be affected due to its superficial positioning, epithelial thickness was chosen as a relevant test parameter and evaluated before and after saline inhalation. Seven vocally healthy participants performed a 10-minute inhalation of saline solution and underwent a combined laryngoscopy and OCT before and after the inhalation therapy. Endoscopy was performed using a newly developed combined laryngoscopy and OCT device. The OCT images were used to estimate the epithelial thickness of the vocal folds. Epithelial thickness measured in all participants before treatment was comparable in size reported in previous studies. Statistical differences before and after inhalation were not detected. The newly developed combined laryngoscopy and OCT procedure enables rapid investigation of the vocal fold epithelium. Inhalation of saline solution did not appear to affect the thickness of the epithelium of the vocal folds in vocally healthy subjects, as evaluated by OCT. N/A. Laryngoscope, 126:E332-E336, 2016.

In vivo investigation of acidified pepsin exposure to porcine vocal fold epithelia.

The study objective was to investigate epithelial changes in response to direct, repeated, acidified pepsin exposures in an in vivo porcine model. We hypothesized that 12 acidified pepsin applications to simulate reflux would elicit a vocal fold response characterized by inflammation, epithelial proliferation, and increased intercellular space, as well as changes in the gene expression of epithelial junctional proteins, ion transporter proteins, and proinflammatory cytokines. Prospective, in vivo study. Pigs received acidified pepsin (pH = 4) or saline (sham) applied directly to vocal folds. Larynges were collected following three exposures per week for 4 weeks. Vocal fold tissue morphology, collagen, and elastin were evaluated histologically. Gene expression of E-cadherin, zona occludens-1, cystic fibrosis transmembrane conductance regulator, epithelial sodium channel, interleukin-1β, tumor necrosis factor-α, and interferon-γ were measured. Ultrastructural alterations, epithelial intercellular space diameter, and microridge height were measured using transmission electron microscopy. There were no significant differences in histology, gene transcripts, epithelial ultrastructure, intercellular space, and microridge height after acidified pepsin exposure. Twelve simulated reflux challenges were insufficient to elicit epithelial changes, demonstrating the resistance of healthy vocal folds to direct, repeated acidified pepsin exposures. These data increase our understanding of healthy vocal fold defenses and lay the groundwork for a prospective, uninjured, nonsurgical, laryngopharyngeal reflux model where pigs can be exposed directly to acidified pepsin.

Functional and Histological Evaluation following Canine Vocal Fold Reconstruction Using Composite Thyroid Ala Perichondrium Flaps.

We evaluated the effects of vocal fold reconstruction using a composite thyroid ala perichondrium flap (CTAP) after unilateral vocal fold stripping in beagles. We hypothesized that CTAP would improve glottic closure, decrease phonation threshold pressure, and decrease perturbation. In addition, vocal folds with CTAP would exhibit neovascularization and fat with increased von Willebrand factor (vWF) and smooth muscle actin (SMA), reflecting neoangiogenesis and flap viability. Randomized controlled trial using beagles. University laboratory. Ten beagles underwent unilateral vocal fold stripping. Dogs in the scar-only group (n = 5) were sacrificed at 1 month. Dogs in the CTAP group (n = 5) underwent ipsilateral reconstruction with CTAP at 1 month and were sacrificed at 2 months. Excised larynx experiments evaluated vocal fold vibration using aerodynamic, acoustic, and mucosal wave measurements. Qualitative evaluation of vocal fold morphology and quantitative analysis of elastin, collagen, glycosaminoglycans, vWF, SMA, and hyaluronic acid were performed. Phonation threshold pressure (P = .005), percent jitter (P = .010), percent shimmer (P = .007), and open quotient (P = .007) were lower in the CTAP group. Neovascularization (P = .0079) and fat (P = .1667) occurred more with CTAP, although the difference in fat was not significant. von Willebrand factor was higher with CTAP vs contralateral normal fold (P = .110), although not statistically significant. Smooth muscle actin was higher with CTAP vs contralateral normal fold (P = .038) and scarred vocal folds (P = .022). Composite thyroid ala perichondrium flap restored glottic closure and vibratory periodicity following vocal fold scarring. Additional investigation on biologic response is warranted. Composite thyroid ala perichondrium flap offers an autologous, vascularized implant that can improve both vocal fold structure and function.

Functional morphology of the Alligator mississippiensis larynx with implications for vocal production.

Sauropsid vocalization is mediated by the syrinx in birds and the larynx in extant reptiles; but whereas avian vocal production has received much attention, the vocal mechanism of basal reptilians is poorly understood. The American alligator (Alligator mississippiensis) displays a large vocal repertoire during mating and in parent-offspring interactions. Although vocal outputs of these behaviors have received some attention, the underlying mechanism of sound production remains speculative. Here, we investigate the laryngeal anatomy of juvenile and adult animals by macroscopic and histological methods. Observations of the cartilaginous framework and associated muscles largely corroborate earlier findings, but one muscle, the cricoarytenoideus, exhibits a heretofore unknown extrinsic insertion that has important implications for effective regulation of vocal fold length and tension. Histological investigation of the larynx revealed a layered vocal fold morphology. The thick lamina propria consists of non-homogenous extracellular matrix containing collagen fibers that are tightly packed below the epithelium but loosely organized deep inside the vocal fold. We found few elastic fibers but comparatively high proportions of hyaluronan. Similar organizational complexity is also seen in mammalian vocal folds and the labia of the avian syrinx: convergent morphologies that suggest analogous mechanisms for sound production. In tensile tests, alligator vocal folds demonstrated a linear stress-strain behavior in the low strain region and nonlinear stress responses at strains larger than 15%, which is similar to mammalian vocal fold tissue. We have integrated morphological and physiological data in a two-mass vocal fold model, providing a systematic description of the possible acoustic space that could be available to an alligator larynx. Mapping actual call production onto possible acoustic space validates the model's predictions.

Biocompatibility and efficacy of collagen/gelatin sponge scaffold with sustained release of basic fibroblast growth factor on vocal fold fibroblasts in 3-dimensional culture.

Treatment of vocal fold scarring remains challenging. We have previously reported the therapeutic effects of local injection of basic fibroblast growth factor (bFGF) in animal models and humans. A novel collagen/gelatin sponge (CGS) is capable of sustained release of bFGF, which compensates for its quick absorption in vivo, avoiding multiple injections. This study aimed to evaluate the biocompatibility and efficacy of the CGS in rat vocal fold fibroblasts prior to human trials. Fibroblasts extracted from Sprague-Dawley rat vocal folds were seeded onto a CGS and then cultivated with bFGF at concentrations of 0, 10, and 100 ng/mL. Vocal fold fibroblast morphology, adhesion, proliferation, and gene expression were measured under these 3-dimensional conditions. Cells adhered to the CGS from day 1. Although no significant differences in cell morphology were detected, cell proliferation was accelerated by bFGF administration. Expression of endogenous bFGF and hepatocyte growth factor was significantly up-regulated at 10 ng/mL bFGF. The expression of procollagen I and procollagen III was significantly suppressed, whereas HAS-1 and HAS-2 were up-regulated at 10 and 100 ng/mL bFGF. The collagen/gelatin sponge is biocompatible with vocal fold fibroblasts and may be useful as a bFGF drug delivery system for the treatment of scarred vocal folds.