Immunohistochemical characterization of benign laryngeal lesions

Histopathologic changes in human true vocal folds: a postmortem study

Several articles describe the gross pathology alterations of the true vocal cords (TVC), but the histopathology descriptions in adults are rare in the literature and are normally associated with neoplasia. The aim of this study is to identify the TVC morphological lesions in adult autopsies. This was a cross-sectional study of 266 adults' larynxes consecutively autopsied from 1993 to 2003. Histochemical and immunohistochemical methods were used for morphological analysis. Considering the morphological analysis, 97 TVC (36.5%) were considered normal. The following lesions were found in the TVC: thickening of the basal membrane of the TVC in 81 patients (30.5%), inflammatory reaction in 66 patients (24.8%), hemorrhage in 19 patients (7.1%), and ulceration in 3 patients (1.1%). Our study demonstrated that the TVC microscopic lesions are frequent, present different morphological patterns, and showed different causes from what had been described until nowadays by the literature. Despite this difference in the morphological pattern, we were able to identify a common lesion pathway for ethiological different diseases.

Vocal Fold Wound Healing: A Review for Clinicians

SUMMARY

The basic science of wound healing is largely omitted from the curriculum of many voice clinicians. This fact is relatively disheartening as most therapeutic manipulation in the realm of laryngology and voice disorders deals with injured tissue. Therefore, the selection of therapeutic tasks for persons with vocal injury should ideally be informed by basic science in wound healing. Recently, several investigators have initiated lines of research to determine the course of vocal fold wound healing and the potential role of therapeutic agents, including behavioral agents. The current review seeks to provide a foundation of basic wound healing science and present the most current data regarding the wound healing process in the vocal folds.

Simulated effects of cricothyroid and thyroarytenoid muscle activation on adult-male vocal fold vibration

Adjustments to cricothyroid and thyroarytenoid muscle activation are critical to the control of fundamental frequency and aerodynamic aspects of vocal fold vibration in humans. The aerodynamic and physical effects of these muscles are not well understood and are difficult to study in vivo. Knowledge of the contributions of these two muscles is essential to understanding both normal and disordered voice physiology. In this study, a three-mass model for voice simulation in adult males was used to produce systematic changes to cricothyroid and thyroarytenoid muscle activation levels. Predicted effects on fundamental frequency, aerodynamic quantities, and physical quantities of vocal fold vibration were assessed. Certain combinations of these muscle activations resulted in aerodynamic and physical characteristics of vibration that might increase the mechanical stress placed on the vocal fold tissue.

Differential cell adhesion to vocal fold extracellular matrix constituents

The human vocal folds are a complex layering of cells and extracellular matrix. Vocal fold extracellular matrix uniquely contributes to the biomechanical viscoelasticity required for human phonation. We investigated the adhesion of vocal fold stellate cells, a novel cell type first cultured by our laboratory, and fibroblasts to eight vocal fold extracellular matrix components: elastin, decorin, fibronectin, hyaluronic acid, laminin and collagen types I, III and IV. Our data demonstrate that these cells adhere differentially to said substrates at 5 to 120 min. Cells were treated with hyaluronidase and Y-27632, a p160ROCK-specific inhibitor, to test the role of pericellular hyaluronan and Rho-ROCK activation in early and mature adhesion. Reduced adhesion resulted; greater inhibition of fibroblast adhesion was observed. We modulated the fibronectin affinity exhibited by both cell types using Nimesulide, an inhibitor of fibronectin integrin receptors alpha5beta1 and alphavbeta3. Our results are important in understanding vocal fold pathologies, wound healing, scarring, and in developing an accurate organotypic model of the vocal folds.

Vestibular folds configuration in vocal nodule

Vocal nodules are among the most common laryngopathies that cause vocal functional disorders. The voice production mechanism is complex and demand interaction of different systems of the human body. The physiological role of the vocal folds as the glottic sound source is evident, however, there is no consensus regarding the vestibular folds' participation/influence in phonation.

AIM

To verify if there is difference in the bidimensional configuration of the vestibular folds between two distinct groups of women, one with the diagnosis of vocal nodules and the other without vocal complaints and vocal fold lesions.

STUDY DESIGN

Clinical with transversal cohort.

MATERIAL AND METHOD

Ninety-six laryngeal images were evaluated, 48 from individuals without vocal complaints and 48 from patients with the diagnosis of vocal nodules. Angles were obtained and bilaterally measured in single frames of the vestibular folds during sustained phonation and those structures were morphologically classified as concave, linear or convex.

RESULTS

Among the 96 vestibular folds evaluated in each group, there was predominance of the concave form, followed by the linear and the convex ones. In the control group, there was a single convex vestibular fold, 27 were linear and 68 were concave folds. In the group of vocal nodules, 8 were convex, 15 were linear and 73 were concave folds. However, the differences among groups were not statistically significant as well as those among the angles, whose average measures were proven quite similar.

CONCLUSION

In the female gender, the vestibular folds presented similar behavior regarding the morphology in both patients with vocal nodules and women without vocal complaints.

Description of microscopic lesions of vestibular folds of autopsied adults and their relationship with cause of death and underlying disease

The increase in invasive methods currently applied to diagnosis airway upper tract infection leads to a possible increase in vestibular folds (VF) lesions. Besides, VF importance in the prevention of the organism against infection pathogens had been stressed and few studies had addressed the microscopic lesions of the VF in autopsied patients because there is no routine VF examination in the postmortem exam.

Aim

The aim of this study is morphological microscopic analyses of the VF from autopsied patients and its correlation with basic disease and cause of death.

Study design

transversal cohort.

Material and Method

We studied 82 larynges collected during the autopsy exam and performed the Hematoxylin -eosin method for morphological analyses.

Results

From the 82 vestibular folds analyzed we observe that 42 (51%) showed an inflammatory reaction. In fifteen (18.3%) vestibular folds we found lymphoid follicular hyperplasia, in eleven (13.4%) diffuse inflammatory infiltrate and in sixteen (19.5%) acute inflammatory reactions. Circulatory diseases were the most frequently underlying diseases found, 31 (37.8%) and from these 20 (67.8%) presented associated vestibular folds inflammatory reaction. The infection diseases were the most frequently cause of death among the patients with inflammatory reaction of the VF.

Conclusion

Besides the anatomic function, VF seem to have a immunological function preventing lower airway infections. Our study demonstrated inflammatory PV reactions in patients with infections diseases as cause of death; this finding could be a consequence of the sepses that leads the patient to death or a different way used by the organism to prevent infection.

Current understanding and review of the literature: vocal fold scarring

Vocal fold scarring is the greatest cause of poor voice after vocal fold injury. Scarring causes a disruption of the viscoelastic layered structure of the lamina propria, an increase in stiffness of the vibratory structure, and glottic incompetence. Current treatments for this complex condition are inconsistent and often produce suboptimal results. Research investigating this condition has dramatically increased over the last several years. The literature has been directed toward understanding vocal fold scarring at the biological level and translating this to the clinical forum. We present an up-to-date, thorough, and scholarly review of the literature in vocal fold scarring since 1996.

Acute histologic effects of extraesophageal reflux on vocal fold healing

This study evaluates how extraesophageal reflux affects membranous vocal fold healing in a canine model. We created membranous vocal fold injuries in the animals and randomly assigned them to topical application of acid and pepsin at pH 2 or pH 6 or of normal saline solution every other day for 12 days. The experimental vocal folds were compared to uninjured, control vocal folds from animals painlessly sacrificed for other reasons. Hematoxylin and eosin, fibronectin, and procollagen I staining were performed for histologic analysis. The injured specimens had three times greater cellular infiltrate (p < or = .001, analysis of variance) and twice as much fibronectin and procollagen I (p < or = .001, analysis of variance) as did the specimens from the control animals. No significant differences or trends were identified for cellular infiltrate, fibronectin, or procollagen I within the injured groups (p > .05, Bonferroni t-test). Acute wound healing did not appear to be influenced by the presence of acid and pepsin at pH 2 or 6 as compared to saline solution.

Advances in our understanding of the Reinke space

PURPOSE OF REVIEW

Normal vocal fold vibration depends critically upon the composition of the Reinke space or the lamina propria extracellular matrix. Alterations in the normal composition of the extracellular matrix result in a loss of normal vibratory function. In this article, the present literature on the Reinke space in normal and disease states is reviewed including publications in the multidisciplinary fields of biomechanics, histology, molecular biology, and tissue engineering.

RECENT FINDINGS

With recent technology advances, the etiology for benign lesions has been investigated with computer models and bioreactors. Particular extracellular matrix constituents in various benign vocal fold lesions--fibronectin, fibromodulin and hyaluronan--appear to be involved in altering the viscoelastic properties of the Reinke space. Significant basic science approaches to the investigation of the characterization of the Reinke space in vocal fold scarring has produced several potential future treatment avenues. Tissue-engineering approaches for regeneration of the Reinke space are the most recent addition to the literature showing promising research directions.

SUMMARY

Voice disorders represent a significant clinical problem. Research attempting to discover the underlying molecular and genetic regulation and homeostasis of the extracellular matrix of the Reinke space are essential. Effective future clinical interventions must be based upon the knowledge of how genetic and biologic features are disturbed in vocal diseases and how they relate to vocal symptoms.

Neto J, Pontes P. Diferenciação histopatológica e imunoistoquímica das alterações epiteliais no nódulo vocal em relação aos pólipos e ao edema de laringe

OBJETIVO: Avaliar, por meio de técnicas histológicas e imunoistoquímicas, o epitélio nos nódulos vocais em relação aos pólipos, ao edema de laringe e às pregas vocais sem lesões macroscópicas. FORMA DE ESTUDO: Clínico retrospectivo. MATERIAL E MÉTODO: Por meio de levantamento de prontuário, foram identificados vinte e seis pacientes com lesões laríngeas inflamatórias (nódulos, pólipos e edema de laringe), que haviam sido submetidos à cirurgia. Pregas vocais sem alterações macroscópicas foram obtidas a partir de autópsia de cadáveres. Para análise do epitélio, foram realizadas colorações pela técnica da hematoxilina-eosina e do ácido periódico de Schiff e técnicas de imunoistoquímica com anticorpos dirigidos contra laminina e colágeno IV. A leitura das lâminas foi realizada por meio de microscopia óptica. RESULTADOS: Houve maior imunoexpressão de laminina e colágeno IV nos nódulos quando comparados aos pólipos (p=0,034 e p=0, 036, respectivamente), assim como quando comparados às pregas vocais sem lesões macroscópicas (p=0,019 e p=0, 021, respectivamente). Nódulos tendem a apresentar maior espessura da membrana basal, quando utilizamos coloração pela técnica do PAS, em relação aos pólipos (p=0,102). O edema de laringe não se diferenciou das demais nas técnicas utilizadas (p> 0,10). CONCLUSÕES: O Nódulo Vocal diferencia-se dos pólipos, nas três técnicas utilizadas para detecção da membrana basal (PAS, laminina, colágeno IV), e das pregas vocais sem lesões macroscópicas em duas das técnicas utilizadas (laminina e colágeno IV). Edema de laringe não se diferencia das demais lesões, nem de pregas vocais sem lesões macroscópicas, quando utilizadas as técnicas anteriormente descritas, para estudo da membrana basal.

Relationship between the morphologic alterations of vocal cords from adult autopsies and the cause of death

PURPOSE

The purpose of this study was to identify the possible alteration in the thickness of the epithelium basal membrane of the vocal cords and correlate it with the cause of death.

METHOD

Larynxes collected from adult autopsies during the period of 1993 to 2001 were utilized. We used the hematoxylin-eosin and periodic acid-Schiff staining methods for the morphological and morphometric analysis.

RESULTS

Sixty-six vocal cords were analysed; increased thickness was identified in 14 cases (21.2%), with equal proportions between the genders. Increased vocal-cord thickness was more frequent in patients of the white ethnicity (12 cases, 85.7%). Respiratory alterations were found in 10 (71.4%) of the cases with increased vocal-cord thickness. Of the patients that were maintained with mechanical ventilation before death, 7 (18.4%) had thickening of the basal membrane. Among the smokers, 9 (19.63%) had basal membrane thickening.

CONCLUSION

No statistically significant differences were found between the cases in which the cause of death was related to respiratory diseases as compared to non-respiratory diseases and the thickening of the basal membrane of the vocal cords. However, new studies are needed in order to verify the etiopathogenesis of this thickening.

Interstitial protein alterations in rabbit vocal fold with scar

Fibrous and interstitial proteins compose the extracellular matrix of the vocal fold lamina propria and account for its biomechanic properties. Vocal fold scarring is characterized by altered biomechanical properties, which create dysphonia. Although alterations of the fibrous proteins have been confirmed in the rabbit vocal fold scar, interstitial proteins, which are known to be important in wound repair, have not been investigated to date. Using a rabbit model, interstitial proteins decorin, fibromodulin, and fibronectin were examined immunohistologically, two months postinduction of vocal fold scar by means of forcep biopsy. Significantly decreased decorin and fibromodulin with significantly increased fibronectin characterized scarred vocal fold tissue. The implications of altered interstitial proteins levels and their affect on the fibrous proteins will be discussed in relation to increased vocal fold stiffness and viscosity, which characterizes vocal fold scar.

Update on the etiology, diagnosis, and treatment of vocal fold nodules, polyps, and cysts

PURPOSE OF REVIEW

Innovative otolaryngologists, speech language pathologists, and voice scientists have continued to advance our understanding of the etiology, diagnosis, and treatment of vocal fold nodules, polyps, and cysts. This article reviews the recent publications over the past 3 years with respect to these advances.

RECENT FINDINGS

Support for the notion that benign vocal fold lesions arise from phonatory trauma and vocal misuse continues to become evident. Changes in the molecular characteristics of the lamina propria in these lesions are beginning to be understood. For diagnostic purposes, the use of innovative technology such as ultrasonography and virtual laryngoscopy is being explored. Continued support for behavior modification as a primary treatment modality for benign vocal fold lesions has been published, and refinements in technical aspects of laryngeal microsurgery persist. Finally, outcomes studies have demonstrated improvements in vocal disability with both behavioral and surgical interventions.

SUMMARY

Clinical and basic research has furthered our understanding of benign vocal fold lesions and has expanded our diagnostic and therapeutic armamentarium for patients with dysphonia arising from these lesions.

Fibronectin and adhesion molecules on canine scarred vocal folds

OBJECTIVE

To examine the expressions of fibronectin and other adhesion molecules on the scarred vocal folds in a short- and long-term animal model.

STUDY DESIGN

Animal model.

METHODS

Six beagles' vocal folds were stripped unilaterally and left untreated. After wounding the vocal folds were harvested from three dogs at 2 months and three dogs at 6 months. The untouched vocal fold was used as a control, and the stripped vocal fold as scarred. Subsequently, the expressions of fibronectin, cadherin, syndecan-1 and syndecan-4 on both vocal folds were examined by immunohistochemical and image analysis.

RESULTS

Compared with the control vocal folds, fibronectin significantly increased in the superficial layer of the lamina propria on the scarred vocal folds at both 2 and 6 months. Co-deposition of collagen was observed only at 6 months. Syndecan-4 was significantly overexpressed at the basal layer cells of the epithelium at both 2 and 6 months. No significant expression of either cadherin or syndecan-1 was detected.

CONCLUSIONS

Scar characteristics at 2 and 6 months are not identical, suggesting that a 2-month period may not be a sufficient to study vocal fold scarring. Adhesion molecules are important in reorganization of extracellular matrix during wound healing because of their binding and adhesion characteristics. The results indicate that fibronectin might be important in providing a scaffold for the deposition of other proteins such as collagen, and the binding characteristics might affect the stiffness of the scarred vocal fold. Prolonged expression of syndecan-4 may reflect the role of focal adhesion during the assembly of scar structure. Ultimately, better understanding of the histological features of the scarred vocal fold might lead to new approaches to treatment.

DNA microarray gene expression analysis of a vocal fold polyp and granuloma

Genome-wide transcriptional profiling has important applications in advancing knowledge of vocal fold biology. With the use of DNA microarray technology, analysis of global patterns of gene expression can reveal unexpected networks of coordinated regulation in the extracellular matrix of the lamina propria. Transcriptional gene expression patterns for 2 vocal fold pathologies--vocal fold polyp (VP; N = 1) and vocal fold granuloma (VG; N = 1) were analyzed by means of DNA microarray analysis for 4,632 human genes using another patient's true vocal fold (TVF; N = 1) as a control. Twenty-four and 29 genes for VG and VP, respectively, were established to be either over- or underexpressed compared to that of TVF. Five-way cluster analysis revealed broad patterns that suggest a potential degree of organization underlying gene expression in these tissues. For the 1 VG, genes involved represent inflammation and wound healing; for the 1 VP, involved genes demonstrate a tempered wound repair response and increased epithelial manifestations. These results successfully demonstrate the use of DNA microarray technology as a new approach for further investigations dissecting vocal fold disease. Further investigation is needed on larger sample sizes to establish transcriptional gene expression patterns for VP and VG.

Fibronectin: an interesting vocal fold protein

A great deal of information is accruing regarding the function of the extracellular matrix. Once thought to be simply a structural entity to surround cells, it is now known to do much more. Fibronectin in particular has received specific attention. Fibronectin is a ubiquitous glycoprotein found most abundantly in the extracellular matrix of regenerating, healing, and embryonic tissue. Vast evidence supports the fact that fibronectin participates in many diverse functions throughout the body that are relevant to vocal fold biology. This article introduces the structure of fibronectin and its isoforms and provides an introduction to some of the many functions it plays. It also reviews the evidence about fibronectin's place in vocal folds and vocal fold pathology. It discusses fibronectin's presence in vocal nodules, vocal polyps, vocal scarring, and Reinke's edema, and reviews the data on its role in mucosal wave impairment. Lastly, it discusses preliminary microarray data that show gene expression for fibronectin to be upregulated in true vocal folds when compared to false vocal folds.

Diversity in voice characteristics--interaction between genes and environment, use of microarray analysis

Genetic information is used by the cells to make proteins. These proteins are then used to perform cellular and tissue functions. This process is briefly reviewed. Research to identify genes and their expression patterns is a fruitful field in the area of voice disorders. Gene expression studies of vocal lesions illustrates why this type of research is important. The role of microarray analysis (MA) to find genes of interest is discussed. Gene expression may be influenced by various environmental factors. This interaction between environment and genes is constantly manifested in many vocal characteristics and disorders. Since the end result of the gene-environment interaction is the production of cellular and tissue proteins, the field of proteomics is relevant to voice disorders. Some voice disorders have been treated successfully through using proteomic approaches.

LEARNING OUTCOMES

(a) Understand the factors that influence genetic expression; (b) display a knowledge of why the study of proteins is important to understand voice characteristics; (c) become familiar with MA, a powerful tool for the study of gene expression; and (d) describe the interaction between genes and environment.

Genotypic and phenotypic expression of vocal fold polyps and Reinke's edema: a preliminary study

Although a great deal of research exists regarding lamina propria composition, no report exists that relates gene expression in benign laryngeal lesions to phenotypic markers. In this study, messenger RNA profiles for extracellular matrix proteins--procollagen I, collagenase, elastase, fibronectin, fibromodulin, decorin, hyaluronic acid synthase 2, and hyaluronidase--were completed on 5 polyps and 4 Reinke's edema specimens. These genotypic profiles were correlated to a videostroboscopic parameter of mucosal wave stiffness, which was used as a measurement of phenotypic expression. Polyps, characterized by stiffer mucosal waves, had higher levels of gene expression, whereas stiffer mucosal wave scores for Reinke's edema were associated with lower gene activity levels. This study supports the hypothesis that there is a relationship between genotypic expression found in polyps and Reinke's edema and phenotype as defined by a loss of or a decreased mucosal wave. The study also gives clues as to the proteins responsible for the phenotype.

Instability of extracellular matrix gene expression in primary cell culture of fibroblasts from human vocal fold lamina propria and tracheal scar

Primary fibroblast cell cultures were established from lamina propria of human vocal fold and tracheal scar. There exists a crucial need to provide new tools for studying voice biology, and one of the first steps is the development of a human primary laryngeal cell culture bank. Because cell lines can lose their differentiated phenotype in culture across passages, documentation of gene expression must be determined for passage populations, for us to have knowledge of cell behavior in vitro. Comparison of messenger RNA gene expression of extracellular matrix proteins (procollagen I, collagenase, elastin, hyaluronic acid synthase 2, hyaluronidase, fibronectin, cd44, fibromodulin, and decorin) across cell passages (3, 4, 5, 6, 10, and 12 fornormal laminapropria and 3, 4, 5, 6, and 10 for tracheal scar) revealed varied growth patterns. Cytogenetic analysis demonstrated relative stability of the karyotypes across passages for the tracheal scar cell cultures, whereas the karyotypes of the normal lamina propria fibroblasts showed instability in in vitro cultures. Recommendations for use of primary cell cultures for further studies of gene expression are made.

Effect of mitomycin-C on vocal fold healing in a canine model

For evaluation of the effect of topical mitomycin-C on vocal fold healing and return of function after surgical excision of mucosa, 6 dogs underwent suspension microlaryngoscopy with bilateral microflap excision of vocal fold mucosa. Topical mitomycin-C, a chemotherapeutic agent and a fibroblast inhibitor, was applied randomly to one side, with the contralateral side serving as the control. Laryngeal videostroboscopy (LVS) was performed on each animal before the operation, at 2 weeks, and before sacrifice at 4 weeks. Both functional analysis with LVS and histologic analysis were performed in a blinded fashion to determine the effect of mitomycin-C on healing. Histologic analysis was augmented with computer morphometrics. The LVS revealed diminished mucosal wave vibration in the vocal folds treated with mitomycin-C, as well as a more atrophic appearance to the vibratory surface. The vocal folds treated with mitomycin-C showed fewer fibroblasts and less collagen within the superficial layer of the lamina propria than the control vocal folds (p < .05, Student's t-test, paired analysis). Inflammatory infiltrate was not significantly different between the two sides. Consistent with the known suppression of fibroblast proliferation by mitomycin-C, the treated vocal folds showed less connective tissue response to the surgical injury. In contrast to the reported positive effects of mitomycin-C on tracheal and glottic stenosis, the observed decrease in the healing response in the present study had negative consequences on the vocal fold vibratory pattern.

Nomenclature of voice disorders and vocal pathology

An improved nomenclature framework is crucial to improve communication regarding voice problems and to advance the field of voice disorders. The subjective nature of the voice evaluation process does not lend itself readily to uniformity and most voice-disordered patients demonstrate multiple pathologic processes. In this article, the authors offer a broad-based nomenclature paradigm for the classification of voice disorders and vocal pathology. Four major categories of voice disorders are identified based on pathophysiology and auditory-perceptual and visual-perceptual observations. As the understanding of vocal fold biomechanics and pathophysiology evolves, it is expected that this nomenclature system will also increase in specificity.

Phonomicrosurgery II: surgical techniques

Optimal vocal outcome is the major goal of treatment of benign non-neoplastic vocal fold lesions. Current phonomicrosurgery techniques are based on a complete understanding of vocal fold anatomy and the physiology of vocal fold vibration. With the knowledge that these lesions typically involve the superficial layer of the lamina propria and not the overlying epithelium, dissection and excision should be limited to this layer. Vocal fold microflap techniques leave the overlying epithelium and the mucosal cover intact to minimize postoperative scarring and possible tethering to the underlying vocal ligament. Surgical excision is followed by a program of vocal rehabilitation.

Cellular physiology of the vocal folds

This article discusses cellular architecture and physiology relevant to phonation biology. The mucociliary blanket and its role in external vocal fold lubrication are presented. The epithelium, basement membrane zone, and lamina propria all have specific roles in oscillating tissue. Three cell types, fibroblast, myofibroblast, and macrophage, maintain important and unique roles. Protein turnover in the lamina propria is important, and slowing matrix turnover may be a leading factor in creating some of the characteristics associated with vocal senescence. Lastly, aspects of cellular health and cellular pathology are discussed.

Comparative histology and vibration of the vocal folds: implications for experimental studies in microlaryngeal surgery

OBJECTIVES/HYPOTHESIS

To determine the most suitable animal model for experimental studies on vocal fold surgery and function by a histological comparison of the microflap surgical plane and laryngeal videostroboscopy (LVS) in different species of animals. A second goal was to determine how the layered vocal fold structure in humans and three different animal species affects surgical dissection within the lamina propria.

STUDY DESIGN

Prospective laboratory.

METHODS

Three larynges each from dogs, monkeys, and pigs were compared with three ex vivo human larynges. Microflap surgery was performed on one vocal fold from each larynx. Both the operated and nonoperated vocal folds were examined histologically using stains specific for elastin, mature collagen, and ground substance. Based on the histological results, LVS was performed on two dogs and two pigs after first performing a tracheotomy for ventilation and airflow through the glottis. Arytenoid adduction sutures were placed to facilitate vocal fold adduction.

RESULTS

The distributions of the collagen and elastin fibers were found to differ among the species with concentrations varying within species. Unlike the human vocal fold, which has a higher elastin concentration in the deeper layers of the lamina propria, both the pig and the dog had a thin band of elastin concentrated just deep to the basement membrane zone in the superficial layer. Just deep to this thin band, the collagen and the elastin were less concentrated. The monkey vocal fold had a very thin mucosal layer with less elastin throughout the mucosa. The microflap dissections in each of the dog, pig, and human vocal folds were similar, being located within that portion of the superficial lamina propria where the elastin and mature collagen are less concentrated. The microflap plane in the monkey vocal fold was more deeply located near the vocalis fibers. Despite the differences in elastin concentration, the microflap plane in both the dog and the pig was found to be similar to that in humans. The dog anatomy was much more suitable for microsuspension laryngoscopy and stroboscopic examination. The dog vocal folds vibrated in a similar fashion to human vocal folds with mucosal waves and vertical phase differences, features not seen in the pig vocal folds.

CONCLUSIONS

Based on both the histological and stroboscopic results, the dog was believed to be a more suitable animal model for studies on vocal fold surgery, acknowledging that no animal's laryngeal anatomy is identical to that of the human. The dog LVS model presented allows for longitudinal laryngeal studies requiring repeated examinations at multiple time periods with histological correlation applied at sacrifice.

Clinicopathologic study and classification of vocal cord cysts

Cysts of the true vocal cords are less common than other laryngeal cysts. They are usually easily recognized and managed. Patients present with complaints of hoarseness and/or dyspnea. We report our experience with 41 cases of cysts located in the true vocal cords. Clinical and histological aspects are reviewed and discussed. A new histological classification is proposed: A: cysts lined by columnar epithelium with mucous content; B: lined by columnar epithelium with cilia; C: lined b squamous epithelium without keratinization; D: lined by squamous epithelium with keratinization.

Biomechanical and histologic observations of vocal fold fibrous proteins

This article discusses the molecular composition of the vocal fold and the relationship of fibrous molecules to the biomechanical and physiological performance of the tissue. The components of the extracellular matrix may be divided into fibrous proteins and interstitial proteins. The fibrous proteins, consisting of collagens and elastins, are the focus of this report. Elastin concentration varies by tissue depth in the vocal folds. Variation of elastin by age is reported, but some controversy exists. The biomechanical terms of stress and strain (and stress-strain curves of human vocal folds) are related to the fibrous proteins of the vocal folds. The fibrous proteins, their role in stress, and their effect on the dynamic range of vocal pitch are presented.

Vocal fold proteoglycans and their influence on biomechanics

OBJECTIVE/HYPOTHESIS

To examine the interstitial proteins of the vocal fold and their influence on the biomechanical properties of that tissue.

STUDY DESIGN

Anatomic study of the lamina propria of human cadaveric vocal folds combined with some viscosity testing.

METHODS

Identification of proteoglycans is performed with histochemical staining. Quantitative analysis is performed using an image analysis system. A rheometer is used for viscosity testing. Three-dimensional rendering program is used for the computer images.

RESULTS

Proteoglycans play an important role in tissue biomechanics. Hyaluronic acid is a key molecule that affects viscosity.

DISCUSSION

The proteoglycans of the lamina propria have important biological and biomechanical effects. The role of hyaluronic acid in determining tissue viscosity is emphasized. Viscosity, its effect on phonatory threshold pressure and energy expended due to phonation is discussed.

CONCLUSION

Proteoglycans, particularly hyaluronic acid, play important roles in determining biomechanical properties of tissue oscillation. Future research will likely make these proteins of important therapeutic interest.

Histomorphometric and laryngeal videostroboscopic analysis of the effects of corticosteroids on microflap healing in the dog larynx

The histologic and functional effects of unilateral, layered corticosteroids on lateral microflap healing in 15 dogs were analyzed. Histologic sections of steroid-treated vocal folds (VFs) were studied with computer morphometry to examine differences in the tissue healing response. Paired analysis revealed increases in the inflammatory infiltrate around the microflap in the steroid-treated VFs at 2, 4, and 6 weeks (6.3%, 30.6%, and 34.9%, all with p < .02). The neovascular response in the steroid-treated VFs was less at 2 weeks (-20.9%, p < .005) but greater at 4 and 6 weeks (16.3% and 4.3%, p < .005). To better characterize the effect of steroids on the healing process, a normal, time-dependent distribution was applied to the histologic data and demonstrated a delay in the steroid-treated VF tissue response of 12 days for the inflammatory infiltrate and 21 days for the neovascular response. Qualitative and quantitative analysis of in vivo laryngeal videostroboscopy (LVS) samples taken preoperatively and at sacrifice could not identify significant differences in appearance, amplitude, mucosal wave, or suppleness between the 2 VFs. Therefore, although corticosteroids cause a delay in wound healing, LVS does not discern differences in microflap characteristics between healing steroid-treated and control VFs at 2, 4, or 6 weeks. If steroids are used, the surgeon should account for a probable delay in wound healing, but should not expect an overall difference in functional outcome.

Medial microflap for excision of benign vocal fold lesions

The goal of microlaryngeal surgery is to treat the pathology while preserving or improving vocal function. The medial microflap technique was thus developed. An incision is made over or abutting the lesion, which is then dissected from the vocal ligament and overlying mucosa. Seventeen patients underwent medial microflap excision of their lesions. Postoperative videostroboscopic examinations revealed the presence of mucosal wave and improved glottic closure in 15 of the 17 patients. Acoustic and perceptual analyses revealed improved voice quality. The medial technique is a modification of the previously described lateral microflap technique. Patients whose stroboscopic examination implies lack of involvement of the vocal ligament are candidates for this technique. By identifying normal histologic planes without extensive dissection, lesions can be excised with minimal interruption of vibratory mechanics.