Diagnosis and treatment of persistent dysphonia after laryngeal surgery: a retrospective analysis of 62 patients

Versatile fiber-reinforced hydrogels to mimic the microstructure and mechanics of human vocal-fold upper layers

Human vocal folds are remarkable soft laryngeal structures that enable phonation due to their unique vibro-mechanical performances. These properties are tied to their specific fibrous architecture, especially in the upper layers, which comprise a gel-like composite called lamina propria. The lamina propria can withstand large and reversible deformations under various multiaxial loadings. Despite their importance, the relationships between the microstructure of vocal folds and their resulting macroscopic properties remain poorly understood. There is a need for versatile models that encompass their structural complexity while mimicking their mechanical features. In this study, we present a candidate model inspired by histological measurements of the upper layers of human vocal folds. Bi-photonic observations were used to quantify the distribution, orientation, width, and volume fraction of collagen and elastin fibers between histological layers. Using established biomaterials, polymer fiber-reinforced hydrogels were developed to replicate the fibrillar network and ground substance of native vocal fold tissue. To achieve this, jet-sprayed poly(ε-caprolactone) fibrillar mats were successfully impregnated with poly(L-lysine) dendrimers/polyethylene glycol hydrogels. The resulting composites exhibited versatile structural, physical and mechanical properties that could be customized through variations in the chemical formulation of their hydrogel matrix, the microstructural architecture of their fibrous networks (i.e., fiber diameter, orientation and volume fraction) and their assembly process. By mimicking the collagen network of the lamina propria with polymer fibers and the elastin/ground substance with the hydrogel composition, we successfully replicated the non-linear, anisotropic, and viscoelastic mechanical behavior of the vocal-fold upper layers, accounting for inter/intra-individual variations. The development of this mimetic model offers promising avenues for a better understanding of the complex mechanisms involved in voice production. STATEMENT OF SIGNIFICANCE: Human vocal folds are outstanding vibrating soft living tissues allowing phonation. Simple physical models that take into account the histological structure of the vocal fold and recapitulate its mechanical features are scarce. As a result, the relations between tissue components, organisation and vibro-mechanical performances still remain an open question. We describe here the development and the characterization of fiber-reinforced hydrogels inspired from the vocal-fold microstructure. These systems are able to reproduce the mechanics of vocal-fold tissues upon realistic cyclic and large strains under various multi-axial loadings, thus providing a mimetic model to further understand the impact of the fibrous network microstructure in phonation.

Risk factors for postoperative vocal fold fibrosis following microlaryngeal surgery

Objective

To analyze the risk factors for postoperative vocal fold fibrosis (PVF) in patients undergoing microlaryngeal surgery (MLS) for benign vocal fold lesions.

Study Design

Retrospective study.

Methods

We retrospectively included patients who had undergone MLS for vocal polyps, nodules, mucus retention cysts, fibrous mass, or Reinke's edema. Data on the patients' clinicodemographic characteristics and intraoperative findings were obtained by reviewing their clinical records. PVF was defined by the presence of an adynamic segment of membranous vocal folds or a marked reduction in mucosal wave amplitude on post-MLS (6 weeks) videolaryngostroboscopy. The risk factors for PVF were analyzed through univariate and multivariate logistic regressions.

Results

This study included 89 patients, of whom 16 (18%) were given a diagnosis of PVF. A significantly increased incidence of PVF was noted in patients with fibrous mass (p < .01). The univariate analysis indicated that lesion attachment to the vocal ligament, prolonged surgical duration (>60 min), and symptom duration (>12 months) were significantly correlated with PVF (p < .05). The multivariate analysis confirmed that diagnosis of fibrous masses, lesion attachment to the vocal ligament and symptom duration are significant risk factors for PVF.

Conclusion

PVF is more common in patients with fibrous masses. Lesions attachment to the vocal ligament and prolonged symptom duration appear to be other significant risk factors for PVF.

Level of Evidence

4.

Duration of Clinical Response After In-Office Steroid Injection for Vocal Fold Scar

OBJECTIVE

To assess the duration of clinical response after in-office vocal fold steroid injection (VFSI) for vocal fold (VF) scar.

METHODS

Demographic and clinical data for in-office VFSI occurring from 2017 to 2020 were collected. Two Speech-Language Pathologists (SLPs) used perceptual evaluation of voice and functional scales to evaluate blinded voice and laryngovideostroboscopy (LVS) samples collected pre- and post-injection across multiple timepoints.

RESULTS

Blinded SLP ratings were used for 30 individual VFs undergoing initial injection in 18 patients. Persistent improvement in voice past 6 months was seen in 57% of patients after VFSI. Multiple measures of voice and amplitude, percent vibrating tissue, and closed phase predominance significantly improved at various follow-up timepoints on average.

CONCLUSION

Accounting for patient heterogeneity and disease progression, in-office VFSI for VF scar is associated with sustained improvement in a subset of patients. Approximately half of patients can expect to experience a lasting improvement in voice. Future studies of larger scale are required to identify patient factors associated with long-term benefit.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:2333-2339, 2023.

Cryotherapy Modifies Extracellular Matrix Expression of Vocal Fold in Rat Models

OBJECTIVES

Vocal fold (VF) scarring is the major cause of voice disorders. Cryotherapy is an effective anti-scarring therapy for skin lesions. The aim of this study was to explore the anti-scarring potential of cryotherapy in vocal folds.

METHODS

The extracellular matrix (ECM) mRNA expression of cryotherapy on normal VF tissue and the histologic results of cryotherapy on vocal fold healing were studied. Fifteen rats were introduced cryotherapy on the normal VF bilaterally and were harvested for real-time polymerase chain reaction (RT-PCR) analysis for collagen I, collagen III, TGFβ1, decorin, fibronectin and HAS1 at 1 day, 3 days and 7 days. Ten rats were unilaterally injured by stripping lamina propria and immediately treated with or without cryotherapy and were harvested at 2 months for histological and immunohistochemical analysis.

RESULTS

Regenerative effect of cryotherapy was validated of ECM gene expression. Histological and immunohistochemical analysis showed significantly increased hyaluronan, decreased collagen, and increased decorin deposition in injury-cryotherapy cohort compared with injury control cohort and normal control cohort.

CONCLUSIONS

Cryotherapy may provide an optimal environment for vocal fold tissue regeneration. The results of the present investigation suggest that cryotherapy has therapeutic potential in prevention and treatment of vocal fold scarring.

Peroxisome Proliferator-Activated Receptor-γ Agonist Attenuates Vocal Fold Fibrosis in Rats via Regulation of Macrophage Activation

Macrophages aid in wound healing by changing their phenotype and can be a key driver of fibrosis. However, the contribution of macrophage phenotype to fibrosis following vocal fold injury remains unclear. Peroxisome proliferator-activated receptor-γ (PPARγ) is expressed mainly by macrophages during early wound healing and regulates the macrophage phenotype. This study aimed to evaluate the effects of pioglitazone (PIO), a PPARγ agonist, on the macrophage phenotype and fibrosis following vocal fold injury in rats. PIO was injected into the rat vocal folds on days 1, 3, 5, and 7 after injury, and the vocal fold lamina propria was evaluated on days 4 and 56 after injury. Moreover, THP-1-derived macrophages were treated with PIO, and the expression of proinflammatory cytokines under lipopolysaccharide/interferon-γ stimulation was analyzed. PIO reduced the expression of Ccl2 both in vivo and in vitro. Furthermore, PIO decreased the density of inducible nitric oxide synthase⁺ CD68⁺ macrophages and inhibited the expression of fibrosis-related factors on day 4 after injury. On day 56 after injury, PIO inhibited fibrosis, tissue contracture, and hyaluronic acid loss in a PPARγ-dependent manner. These results indicate that PPARγ activation could inhibit accumulation of inflammatory macrophages and improve tissue repair. Taken together, these findings imply that inflammatory macrophages play a key role in vocal fold fibrosis.

Effect of Proton Pump Inhibitor on the Outcome of Laryngeal Microsurgery in Patients With Vocal Fold Mucosal Disease With Reflux Symptoms

OBJECTIVES

To evaluate the effect of proton pump inhibitor (PPI) after laryngeal microsurgery (LMS) in patients with benign vocal fold (VF) mucosal disease and in patients with overt reflux symptom according to subjective and objective voice assessment.

METHODS

The improvement of voice handicap index-10 (VHI-10) score, reflux symptom index (RSI) score, grade, roughness, breathiness, asthenia, and strain (GRBAS) score, Jitter, Shimmer, noise to harmonics ratio (NHR), maximum phonation time of acoustic voice analysis RESULTS: A total of 47 patients (PPI group [n = 24] and non-PPI group [n = 23]) completed the study. The scores for VHI-10, RSI, GRBAS, and acoustic parameters significantly improved in both groups after surgery. In the subgroup analysis of patients with overt reflux symptoms (RSI ≥ 13; non-PPI group [n = 12], PPI group [n = 15]), significant between-group differences were observed in terms of the improvement in NHR and the strain factor.

CONCLUSION

Postoperative PPI administration in patients with VF benign mucosal disease with reflux symptoms might improve subjective and objective voice outcomes after LMS.

Development and validation of a 3D laryngeal model in surgical skills training

OBJECTIVE

To present and validate a new simulation model for endoscopic phonomicrosurgery training as an improved teaching method.

METHODS

A low-cost artificial model was assembled using 3D printing, silicone, and gelatin. The study was designed to test the model's ability to carry out training and teaching of endoscopic phonomicrosurgery. The synthetic model was built to simulate normal and pathological vocal folds such as polyps, intracordal cysts and keratoses, made of silicone and gelatin and embedded in a larynx framework made by 3D printing. Simulations of endoscopic surgical procedures were performed and documented through photographs and videos and the images were submitted to the evaluation of a group of 17 otorhinolaryngologists who used a Likert scale questionnaire. The responses were submitted to an agreement analysis using the sum of the scores obtained for the responses as an appropriate level of validation. Cronbach's alpha index was calculated to measure the degree of the questionnaire internal consistency.

RESULT

The evaluations indicated maximum approval for the model adequacy for use in practical classes and for the teaching of the procedures, as well as in the overall satisfaction with the model in the use of surgical training.

CONCLUSION

The present proposal for training laryngeal endoscopic surgery in a 3D synthetic model is a viable option according to the validation methodology used in the present study.

First-line treatment of exudative vocal fold-lesions by in-office local corticosteroid injection: A literature review

OBJECTIVES

There are emerging reports of the effectiveness of in-office awake vocal-fold corticosteroid injection in the treatment of exudative vocal-fold lesions. The aim of this study was to review this therapy and specify indications, practical modalities and outcomes.

STUDY DESIGN

Systematic review of the literature without meta-analysis.

METHODS

A systematic review by PubMed search for the period January 2000 to December 2018 was carried out.

RESULTS

Nine articles were included, for a total of 502 lesions: nodules (46.4%), polyps (31.7%), and Reinke's edema (21.9%). Submucosal injection of low-dose triamcinolone acetonide (0.1 to 0.3mL) was transoral, transcutaneous or transnasal via flexible endoscope with operating channel. Lesion volume was significantly reduced in more than 90% of cases, with significant vocal improvement in all studies. Relapse rates ranged between 4% and 31%, with time to relapse of 1 to 40 months.

CONCLUSIONS

First-line treatment of exudative glottic lesions by submucosal corticosteroid injection provides at least transient significant reduction in lesion volume and vocal improvement. It is consensually reserved to moderate-sized mainly exudative lesions without fibrosis. In-office injection provides an immediate therapeutic response in case of vocal impairment, enabling surgery under general anesthesia to be postponed.

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

OBJECTIVES/HYPOTHESIS

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.

STUDY DESIGN

Animal experiment.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:E436-E443, 2020.

Regenerative potential of basic fibroblast growth factor contained in biodegradable gelatin hydrogel microspheres applied following vocal fold injury: Early effect on tissue repair in a rabbit model

Introduction

Postoperative dysphonia is mostly caused by vocal fold scarring, and careful management of vocal fold surgery has been reported to reduce the risk of scar formation. However, depending on the vocal fold injury, treatment of postoperative dysphonia can be challenging.

Objective

The goal of the current study was to develop a novel prophylactic regenerative approach for the treatment of injured vocal folds after surgery, using biodegradable gelatin hydrogel microspheres as a drug delivery system for basic fibroblast growth factor.

Methods

Videoendoscopic laryngeal surgery was performed to create vocal fold injury in 14 rabbits. Immediately following this procedure, biodegradable gelatin hydrogel microspheres with basic fibroblast growth factor were injected in the vocal fold. Two weeks after injection, larynges were excised for evaluation of vocal fold histology and mucosal movement.

Results

The presence of poor vibratory function was confirmed in the injured vocal folds. Histology and digital image analysis demonstrated that the injured vocal folds injected with gelatin hydrogel microspheres with basic fibroblast growth factor showed less scar formation, compared to the injured vocal folds injected with gelatin hydrogel microspheres only, or those without any injection.

Conclusion

A prophylactic injection of basic fibroblast growth factor -containing biodegradable gelatin hydrogel microspheres demonstrates a regenerative potential for injured vocal folds in a rabbit model.

Assessment of Patient Outcomes After Adjuvant Vocal Fold Steroid Injection for Fibrosis After Microlaryngeal Surgery

Importance

Microlaryngeal surgery (MLS) is one of the most common procedures in laryngology; however, in cases of postoperative fibrosis, few remedial options are available.

Objective

To investigate the outcomes of vocal fold steroid injection (VFSI) as an adjuvant treatment for fibrosis after MLS.

Design, Setting, and Participants

Case series of 228 consecutive patients who underwent MLS for benign vocal lesions between January 2014 and December 2016 at a tertiary medical center. Adjuvant VFSI was performed in 25 patients (11%) with postoperative fibrosis, defined as severely decreased or absent mucosal wave on videolaryngostroboscopy (VLS) lasting for longer than 1 month postoperatively. Data were analyzed from July 1, 2018 to April 30, 2019.

Intervention

All adjuvant VFSIs were performed in the office under local anesthesia and were repeated monthly if the status of the mucosal wave did not return to normal or mildly decreased on the follow-up VLS.

Main Outcomes and Measures

The outcome parameters, namely, the 10-item Voice Handicap Index (VHI-10), smoothed cepstral peak prominence (CPP) of recorded voice samples, and mucosal wave status on VLS, were measured before and after MLS and after adjuvant VFSI.

Results

In this case series of 228 patients (72 men and 156 women; mean [SD] age, 42.8 [12.3] years), 25 had a decreased or absent mucosal wave after MLS, indicating postoperative fibrosis. Of these patients, 22 presented with deep-seated lesions that were removed using a microflap approach. After 1 course of adjuvant VFSI in 17 patients and 2 serial monthly injections in 8 patients, VFSI was associated with improved VHI-10 scores (mean, 24.4 points preoperatively, 22.1 points postoperatively, and 12.9 points after VFSI) that were comparable to the scores of the other 203 patients without vocal fold fibrosis after MLS (mean, 24.8 points preoperatively, 11.7 points postoperatively). Adjuvant VFSI was also associated with improved CPP (mean, 4.04 preoperatively, 4.23 postoperatively, and 5.11 after VFSI) that was comparable to the CPP of the other patients without postoperative fibrosis (mean, 4.33 preoperatively and 5.15 postoperatively). Overall, 19 (76%) of 25 patients with vocal fold fibrosis after MLS had normal (n = 11) or mildly decreased (n = 8) mucosal wave after adjuvant VFSI.

Conclusions and Relevance

Adjuvant VFSI appeared to be associated with improvements in mucosal wave, voice quality, and subjective perception of dysphonia in patients with fibrosis after MLS, with outcomes comparable to those of the other patients without fibrosis. Adjuvant VFSI may be considered a rescue technique, reducing the rate of fibrosis after MLS from 11% to 3%.

Towards a Physiological Scale of Vocal Fold Agent-Based Models of Surgical Injury and Repair: Sensitivity Analysis, Calibration and Verification

Agent based models (ABM) were developed to numerically simulate the biological response to surgical vocal fold injury and repair at the physiological level. This study aimed to improve the representation of existing ABM through a combination of empirical and computational experiments. Empirical data of vocal fold cell populations including neutrophils, macrophages and fibroblasts were obtained using flow cytometry up to four weeks following surgical injury. Random Forests were used as a sensitivity analysis method to identify model parameters that were most influential to ABM outputs. Statistical Parameter Optimization Tool for Python was used to calibrate those parameter values to match the ABM-simulation data with the corresponding empirical data from Day 1 to Day 5 following surgery. Model performance was evaluated by verifying if the empirical data fell within the 95% confidence intervals of ABM outputs of cell quantities at Day 7, Week 2 and Week 4. For Day 7, all empirical data were within the ABM output ranges. The trends of ABM-simulated cell populations were also qualitatively comparable to those of the empirical data beyond Day 7. Exact values, however, fell outside of the 95% statistical confidence intervals. Parameters related to fibroblast proliferation were indicative to the ABM-simulation of fibroblast dynamics in final stages of wound healing.

Vocal fold scars: a common classification proposal by the American Laryngological Association and European Laryngological Society

PURPOSE

Vocal fold scar is one the most challenging benign laryngeal pathologies. The purpose of this paper is to propose a classification that will allow for a common description of this entity between laryngologists, prevent discrepancies in interpretation, allow for comparison of related studies, and offer a training tool for young laryngologists.

METHODS/RESULTS

Based on the depth and laterality of scarring, we propose 4 types: type I, characterized by atrophy of lamina propria with/without affected epithelium; type II, where the epithelium, lamina propria, and muscle are affected; type III, where the scar is located on the anterior commissure; type IV, which includes extended scar formation in both anteroposterior and rostro-caudal axis with significant loss of vocal fold mass.

CONCLUSION

We believe that our proposal is comprehensive and encompasses all existing iatrogenic and non-iatrogenic etiologies in a simple and concise manner. It also serves its purpose as a descriptive, comparative, and training tool.

Pathophysiology of Fibrosis in the Vocal Fold: Current Research, Future Treatment Strategies, and Obstacles to Restoring Vocal Fold Pliability

Communication by voice depends on symmetrical vibrations within the vocal folds (VFs) and is indispensable for various occupations. VF scarring is one of the main reasons for permanent dysphonia and results from injury to the unique layered structure of the VFs. The increased collagen and decreased hyaluronic acid within VF scars lead to a loss of pliability of the VFs and significantly decreases their capacity to vibrate. As there is currently no definitive treatment for VF scarring, regenerative medicine and tissue engineering have become increasingly important research areas within otolaryngology. Several recent reviews have described the problem of VF scarring and various possible solutions, including tissue engineered cells and tissues, biomaterial implants, stem cells, growth factors, anti-inflammatory cytokines antifibrotic agents. Despite considerable research progress, these technical advances have not been established as routine clinical procedures. This review focuses on emerging techniques for restoring VF pliability using various approaches. We discuss our studies on interactions among adipose-derived stem/stromal cells, antifibrotic agents, and VF fibroblasts using an in vitro model. We also identify some obstacles to advances in research.

Paired versus two-group experimental design for rheological studies of vocal fold tissues

Vibratory function of the vocal folds is largely determined by the rheological properties or viscoelastic shear properties of the vocal fold lamina propria. To date, investigation of the sample size estimation and statistical experimental design for vocal fold rheological studies is nonexistent. The current work provides the closed-form sample size formulas for two major study designs (i.e. paired and two-group designs) in vocal fold research. Our results demonstrated that the paired design could greatly increase the statistical power compared to the two-group design. By comparing the variance of estimated treatment effect, this study also confirms that ignoring within-subject and within-vocal fold correlations during rheological data analysis will likely increase type I errors. Finally, viscoelastic shear properties of intact and scarred rabbit vocal fold lamina propria were measured and used to illustrate theoretical findings in a realistic scenario and project sample size requirement for future studies.

Application of a Landmark-Based Method for Acoustic Analysis of Dysphonic Speech

AIM

Speakers with dysphonia often report difficulty with maintaining intelligibility in noisy environments; however, there is no objective method for characterizing this difficulty. Landmark-based analysis is a linguistically-motived, knowledge-based speech analysis technique, which may serve as the basis of acoustic tool for describing the intelligibility deficit. As the first step toward development of such a tool, this study examined whether Landmark-based analysis could describe acoustic differences between normal and dysphonic speech.

METHOD

The recordings subjected to the Landmark-based analysis were the first sentence of the Rainbow Passage from 33 speakers with normal voice and 36 speakers with dysphonia. These recordings were selected from the Kay Elemetrics Database of Disordered Voice. The between-group difference was evaluated based on counts of certain Landmarks (LM).

RESULTS

The average counts of all LMs were significantly greater in normal speech, t(66.85) = 2.36, P = 0.02. When the group-difference was examined for each LM, dysphonic speech had more [g] and [b] LMs and fewer [s] LMs than normal speech (P < 0.01 for all cases). A classification tree model identified [+s] and [+b] LMs are the primary predictors for the dysphonic speech. The model's misclassification rate was 7.24%.

CONCLUSIONS

This preliminary investigation demonstrates that LM-based analysis is capable of differentiating dysphonic speech from normal speech. This encouraging result rationalizes future examinations of LM analysis in other areas of interest. For example, LM-based measures could conceivably be used as to quantify general intelligibility, and/or provide insight into underlying mechanisms of intelligibility deficits.

The effects of cryotherapy on vocal fold healing in a rabbit model

OBJECTIVES/HYPOTHESIS

Cryotherapy has been shown to be a scarless treatment modality for dermal lesions; however, there are limited data addressing the effect of cryotherapy on vocal fold tissue. The aim of this study was to clarify the effectiveness of cryotherapy for prevention of postsurgical vocal fold scarring.

STUDY DESIGN

Prospective animal study in rabbits.

METHODS

The lamina propria of 20 rabbit vocal folds was bilaterally stripped, followed by randomized unilateral cryotherapy. Five larynges were harvested for real-time polymerase chain reaction (RT-PCR) analysis at 1 day, 3 days, and 7 days postinjury. The remaining five were harvested for histologic analysis at 3 months. Images of the healing phase were recorded by laryngoscopy. Analyses of RT-PCR for cyclooxygenase (COX)-2, interleukin (IL)-6, collagen I, collagen III, matrix metallopeptidase 1 (MMP1), transforming growth factor β (TGFβ1), α smooth muscle actin (α-SMA), and hyaluronan synthase 1 (HAS1) were completed. Histological samples were completed for collagen and hyaluronic acid analysis.

RESULTS

RT-PCR results revealed that higher expressions of HAS1 and MMP1 and lower expressions of COX-2, IL-6, collagen I, collagen III, TGFβ1, and α-SMA were observed, and histological examination showed significantly increased hyaluronic acid, decreased deposition, and more organized configuration of collagen in injury with the cryotherapy cohort compared with the injury cohort.

CONCLUSIONS

Cryotherapy can inhibit the inflammatory reaction and simulate a fetal healing environment in extracellular matrix synthesis to regenerate vocal fold tissue with less fibrosis. Histological results showed that cryotherapy achieves a mature healing result with less scar, which tends to return to normal. In summary, the findings of this study suggest that administration of cryotherapy at the time of injury has the potential to minimize vocal fold scarring.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:E151-E157, 2019.

Background Factors and Subjective Voice Symptoms in Patients with Acquired Vocal Fold Scarring and Sulcus Vocalis

OBJECTIVE

Vocal fold scarring (VFS) and sulcus vocalis (SV) often result in severe and chronic voice disorders. This study compares subjective voice complaints as rated with the Voice Handicap Index and etiological factors for patients with VFS and SV.

PATIENTS AND METHODS

Data were collected from the medical records at the Department of Otorhinolaryngology, Karolinska University Hospital, for 27 VFS patients and 27 SV patients. Descriptive background factors were compared between the groups and data were compared from the Swedish Voice Handicap Index (Sw-VHI) questionnaires.

RESULTS

Previous laryngeal surgery/trauma was significantly more common for the patients with VFS. The SV group had significantly more persistent dysphonia since childhood. It was significantly more common to have a non-Germanic language origin among the SV patients. VFS and SV rated high for the total median Sw-VHI scores. The VFS group's total Sw-VHI and the three domain scores were significantly higher compared to the SV group. The physical domain showed a significantly higher score when compared to the functional and emotional domains in the SV cohort and when compared to the emotional domain in the VFS cohort.

CONCLUSION

There are significant differences between the VFS group and SV group regarding etiological factors as well as the Sw-VHI. The degree and profile of VHI should be considered when selecting patients and evaluating the result of new treatments for this group of patients.

Macrophage Response to Allogeneic Adipose Tissue-Derived Stromal Cells in Hyaluronan-Based Hydrogel in a Porcine Vocal Fold Injury Model

OBJECTIVE

Adipose tissue-derived stromal cells (ASC) embedded in hyaluronan scaffold is a beneficial prophylactic treatment for vocal fold (VF) surgical scar. Here, we investigated the macrophage inflammatory response to allogeneic ASC-constructs and identified changes in lamina propria extracellular matrix.

METHOD

Pig ASC were characterized and transfected with GFP+ lentivirus. Thirty-three pigs underwent VF biopsies, and after 3 days, gel alone, gel+pASC, placebo, or pASC alone was injected into wound bed. Animals were sacrificed 3, 7, or 26 days post-injection. Flow cytometry; qPCR for NF-α, TGFβ, IL-10, IL-4, IFNγ, IL-12, FGF2, Col1A1, and HGF; and immunohistochemistry for collagen, elastin, HA, and fibronectin were performed to characterize macrophage phenotype, quantify cytokine transcription, analyze extracellular matrix remodeling, and track GFP+ cells.

RESULTS

No significant differences were found in SWC3+/SWC9+ phenotype or mRNA expression between cells+gel, gel, or placebo. The ASC alone exhibited significantly greater collagen, gel alone resulted in significantly less hyaluronan, and gel+pASC significantly more fibronectin (all P < .05). The pASC-GFP+ were detected 26 days post-injection.

CONCLUSIONS

The ASC-constructs were biocompatible; they did not influence the macrophage inflammatory response or provoke increases in collagen expression. Long-term engraftment was confirmed.

Practice variations in voice treatment selection following vocal fold mucosal resection

OBJECTIVES/HYPOTHESIS

To characterize initial voice treatment selection following vocal fold mucosal resection in a Medicare population.

STUDY DESIGN

Retrospective analysis of a large, nationally representative Medicare claims database.

METHODS

Patients with > 12 months of continuous Medicare coverage who underwent a leukoplakia- or cancer-related vocal fold mucosal resection (index) procedure during calendar years 2004 to 2009 were studied. The primary outcome of interest was receipt of initial voice treatment (thyroplasty, vocal fold injection, or speech therapy) following the index procedure. We evaluated the cumulative incidence of each postindex treatment type, treating the other treatment types as competing risks, and further evaluated postindex treatment utilization using the proportional hazards model for the subdistribution of a competing risk. Patient age, sex, and Medicaid eligibility were used as predictors.

RESULTS

A total of 2,041 patients underwent 2,427 index procedures during the study period. In 14% of cases, an initial voice treatment event was identified. Women were significantly less likely to receive surgical or behavioral treatment compared to men. From age 65 to 75 years, the likelihood of undergoing surgical treatment increased significantly with each 5-year age increase; after age 75 years, the likelihood of undergoing either surgical or behavioral treatment decreased significantly every 5 years. Patients with low socioeconomic status were significantly less likely to undergo speech therapy.

CONCLUSION

The majority of Medicare patients do not undergo voice treatment following vocal fold mucosal resection. Further, the treatments analyzed here appear disproportionally utilized based on patient sex, age, and socioeconomic status. Additional research is needed to determine whether these observations reflect clinically explainable differences or disparities in care.

LEVEL OF EVIDENCE

2c. Laryngoscope, 126:2505-2512, 2016.

Quantitative differentiation of normal and scarred tissues using second-harmonic generation microscopy

The aim of this study was to differentiate normal and scarred hamster cheek pouch samples by applying a quantitative image analysis technique for determining collagen fiber direction and density in second-harmonic generation microscopy images. This paper presents a collagen tissue analysis of scarred cheek pouches of four adult male Golden Syrian hamsters as an animal model for vocal fold scarring. One cheek pouch was scarred using an electrocautery unit and the other cheek was used as a control for each hamster. A home-built upright microscope and a compact ultrafast fiber laser were used to acquire depth resolved epi-collected second-harmonic generation images of collagen fibers. To quantify the average fiber direction and fiber density in each image, we applied two-dimensional Fourier analysis and intensity thresholding at five different locations for each control and scarred tissue sample, respectively. The resultant depth-resolved average fiber direction variance for scarred hamster cheek pouches (0.61 ± 0.03) was significantly lower (p < 0.05) than control tissue (0.73 ± 0.04), indicating increased fiber alignment within the scar. Depth-resolved average voxel density measurements indicated scarred tissues contained greater (p < 0.005) fiber density (0.72 ± 0.09) compared to controls (0.18 ± 0.03). In the present study, image analysis of both fiber alignment and density from depth-resolved second-harmonic generation images in epi-detection mode enabled the quantification of the increased collagen fiber deposition and alignment typically observed in fibrosis. The epi-detection geometry is the only viable method for in vivo imaging as well as imaging thick turbid tissues. These quantitative endpoints, clearly differentiating between control and scarred hamster cheek pouches, provide an objective means to characterize the extent of vocal fold scarring in vivo in preclinical and clinical research. In particular, this non-invasive method offers advantages for monitoring scar treatments in live animals and following the effects of scarring-related treatments such as application of steroids or drugs targeting pathways involved in fibrosis. SCANNING 38:684-693, 2016. © 2016 Wiley Periodicals, Inc.

The use of injectable calcium hydroxylapatite in the surgically pretreated larynx with glottal insufficiency

OBJECTIVES/HYPOTHESIS

To evaluate the efficacy of vocal fold (VF) augmentation with calcium hydroxylapatite (CaHA) microspheres in the surgically pretreated larynx with glottal insufficiency.

STUDY DESIGN

Prospective clinical pilot study.

METHODS

After several prior reconstructive attempts (following tumor resection, VF paralysis, in sulcus vocalis, and VF scarring), CaHA was injected under general anaesthesia using a transoral microlaryngoscopic approach in 10 patients with residual glottal insufficiency ≤1.5 mm. The postinterventional result was assessed after 1 day, and 1 and 3 months. Evaluation of augmentation comprised intraoperative video/photo documentation, pre-/postoperative videolaryngostroboscopy, as well as established subjective and objective voice function diagnostics (Grade, Roughness, Breathiness [GRB] Scale; Voice Handicap Index; voice range profile; and acoustic-aerodynamic analysis).

RESULTS

In the pretreated VF with no or minimal lamina propria remaining, the exact placement of CaHA was not possible due to unpredictable propagation into the scarred tissue. The results showed an insufficient postoperative augmentation. Accordingly, the voice function did not improve. However, a significant increase of the vocal range from 6.2 ± 3.2 to 8.7 ± 3.9 semitones was observed in the speaking voice profile (P =.02). All other acoustic and aerodynamic parameters remained on the whole unchanged; the slight differences between pre- and postoperative findings were not significant.

CONCLUSIONS

The application of CaHA in the surgically pretreated scarred larynx is not reliable to achieve a sufficient glottal closure and a satisfactory improvement of voice. Though CaHA is a welcome addition to our armamentarium against glottal insufficiency, the suitability for augmentation of scar tissue in the larynx must be considered carefully in each individual case.

LEVEL OF EVIDENCE

4 Laryngoscope, 127:1125-1130, 2017.

Is Acupuncture Efficacious for Treating Phonotraumatic Vocal Pathologies? A Randomized Control Trial

OBJECTIVES

To investigate the effectiveness of acupuncture in treating phonotraumatic vocal fold lesions.

STUDY DESIGN/METHODS

A total of 123 dysphonic individuals with benign vocal pathologies were recruited. They were given either genuine acupuncture (n = 40), sham acupuncture (n = 44), or no treatment (n = 39) for 6 weeks (two 30-minute sessions/wk). The genuine acupuncture group received needles puncturing nine voice-related acupoints for 30 minutes, two times a week for 6 weeks, whereas the sham acupuncture group received blunted needles stimulating the skin surface of the nine acupoints for the same frequency and duration. The no-treatment group did not receive any intervention but attended just the assessment sessions. One-hundred seventeen subjects completed the study (genuine acupuncture = 40; sham acupuncture = 43; and no treatment = 34), but only 84 of them had a complete set of vocal functions and quality of life measures (genuine acupuncture = 29; sham acupuncture = 33; and no-treatment = 22) and 42 of them with a complete set of endoscopic data (genuine acupuncture = 16; sham acupuncture = 15; and no treatment = 11).

RESULTS

Significant improvement in vocal function, as indicated by the maximum fundamental frequency produced, and also perceived quality of life, were found in both the genuine and sham acupuncture groups, but not in the no-treatment group. Structural (morphological) improvements were, however, only noticed in the genuine acupuncture group, which demonstrated a significant reduction in the size of the vocal fold lesions.

CONCLUSIONS

The findings showed that acupuncture of voice-related acupoints could bring about improvement in vocal function and healing of vocal fold lesions.

Cell Production in Injured Vocal Folds: A Rat Study

Objectives:

Fibroblasts are reported to play an important role in producing the extracellular matrix of the vocal fold. However, no reports have focused on how and where these cells are generated in the vocal fold after injury. To reveal the characteristics of vocal fold cell production, we investigated cell proliferation in the acute phase of wound healing.

Methods:

Using a telescope for guidance, we made an incision in the middle region of the vocal fold tissue in 24 rats and performed immunohistochemical staining for vimentin, α-smooth muscle actin, and 5-bromo-2-deoxyuridine.

Results:

After injury, epithelialization occurred with a peak at day 1, and fibroblasts proliferated in the lamina propria with a peak at day 3, whereas those in the macula flava did not show any increased proliferation.

Conclusions:

It is suggested that the fibroblasts in the macula flava have functions different from those of fibroblasts in the lamina propria and that the macula flava does not serve as a cell source for the vocal fold in response to injury.

Histological Effect of Basic Fibroblast Growth Factor on Chronic Vocal Fold Scarring in a Rat Model

OBJECTIVES

Vocal fold scarring is one of the most challenging laryngeal disorders to treat and there are currently no consistently effective treatments available. Our previous studies have shown the therapeutic potential of basic fibroblast growth factor (bFGF) for vocal fold scarring. However, the histological effects of bFGF on scarred vocal fold have not been elucidated. The aim of this study was to examine the histological effects of bFGF on chronic vocal fold scarring.

METHODS

Sprague-Dawley rats were divided into phosphate buffered saline (sham) and bFGF groups. Unilateral vocal fold stripping was performed and the drug was injected into the scarred vocal fold for each group 2 months postoperatively. Injections were performed weekly for 4 weeks. Two months after the last injection, larynges were harvested and histologically analyzed.

RESULTS

A significant increase of hyaluronic acid was observed in the vocal fold of the bFGF group compared with that of the sham group. However, there was no remarkable change in collagen expression nor in vocal fold contraction.

CONCLUSION

Significant increase of hyaluronic acid by local bFGF injection was thought to contribute to the therapeutic effects on chronic vocal fold scarring.

Biomechanical Screening of Cell Therapies for Vocal Fold Scar

Candidate cell sources for vocal fold scar treatment include mesenchymal stromal cells from bone marrow (BM-MSC) and adipose tissue (AT-MSC). Mechanosensitivity of MSC can alter highly relevant aspects of their behavior, yet virtually nothing is known about how MSC might respond to the dynamic mechanical environment of the larynx. Our objective was to evaluate MSC as a potential cell source for vocal fold tissue engineering in a mechanically relevant context. A vibratory strain bioreactor and cDNA microarray were used to evaluate the similarity of AT-MSC and BM-MSC to the native cell source, vocal fold fibroblasts (VFF). Posterior probabilities for each of the microarray transcripts fitting into specific expression patterns were calculated, and the data were analyzed for Gene Ontology (GO) enrichment. Significant wound healing and cell differentiation GO terms are reported. In addition, proliferation and apoptosis were evaluated with immunohistochemistry. Results revealed that VFF shared more GO terms related to epithelial development, extracellular matrix (ECM) remodeling, growth factor activity, and immune response with BM-MSC than with AT-MSC. Similarity in glycosaminoglycan and proteoglycan activity dominated the ECM analysis. Analysis of GO terms relating to MSC differentiation toward osteogenic, adipogenic, and chondrogenic lineages revealed that BM-MSC expressed fewer osteogenesis GO terms in the vibrated and scaffold-only conditions compared to polystyrene. We did not evaluate if vibrated BM-MSC recover osteogenic expression markers when returned to polystyrene culture. Immunostaining for Ki67 and cleaved caspase 3 did not vary with cell type or mechanical condition. We conclude that VFF may have a more similar wound healing capacity to BM-MSC than to AT-MSC in response to short-term vibratory strain. Furthermore, BM-MSC appear to lose osteogenic potential in the vibrated and scaffold-only conditions compared to polystyrene, potentially attenuating the risk of osteogenesis for in vivo applications.

Reinke Edema: Watch For Vocal Fold Cysts

Reinke edema is one of the common cause of dysphonia middle-aged population, and severe thickening of vocal folds require surgical treatment. Smoking plays a major role on etiology. Vocal fold cysts are also benign lesions and vocal trauma blamed for acquired cysts. We would like to present 3 cases with vocal fold cyst related with Reinke edema. First case had a subepidermal epidermoid cyst with Reinke edema, which could be easily observed before surgery during laryngostroboscopy. Second case had a mucous retention cyst into the edematous Reinke tissue, which was detected during surgical intervention, and third case had a epidermoid cyst that occurred 2 months after before microlaryngeal operation regarding Reinke edema reduction. These 3 cases revealed that surgical management of Reinke edema needs a careful dissection and close follow-up after surgery for presence of vocal fold cysts.

Change in diagnosis and treatment following specialty voice evaluation: A national database analysis

OBJECTIVE

We evaluated the association between specialty voice evaluation and changes in laryngeal diagnosis and treatment in patients with laryngeal/voice disorders.

STUDY DESIGN

Retrospective analysis of a large, national administrative U.S. claims database.

METHODS

Patients included were identified with a laryngeal disorder based on International Classification of Diseases, Ninth Revision, Clinical Modification codes, from January 1, 2004, to December 31, 2008, and had been seen by an otolaryngologist as an outpatient and had a specialty voice evaluation designated by videolaryngostroboscopy (VLS) within 90 days of the last laryngoscopy. Patient diagnosis at the last laryngoscopy visit and the subsequent initial VLS visit were collected. Specific treatment modalities were tabulated for the 30-day period after the last laryngoscopy and for 30 days after the VLS.

RESULTS

A total of 168,444 unique patients saw an otolaryngologist for 273,616 outpatient visits. Of those, 6.1% had a VLS performed, of which 4,000 (23.8%) occurred within 90 days of the last laryngoscopy, with a median interval of 30 days (interquartile range 15-50 days). Half of the patient visits had a change in laryngeal diagnosis. Changes in use of antibiotics, proton pump inhibitors, voice therapy, and surgical intervention were seen after specialty voice evaluation.

CONCLUSIONS

Specialty voice evaluation was associated with changes in laryngeal diagnosis and treatment. Further study is needed to assess the impact on health care costs and patient outcomes.

Homeostasis of hyaluronic acid in normal and scarred vocal folds

OBJECTIVES/HYPOTHESIS

Vocal fold scarring is one of the most challenging laryngeal disorders to treat. Hyaluronic acid (HA) is the main component of lamina propria, and it plays an important role in proper vocal fold vibration and is also thought to be important in fetal wound healing without scarring. Although several animal models of vocal fold scarring have been reported, little is known about the way in which HA is maintained in vocal folds. The purpose of this study was to clarify the homeostasis of HA by examining the expression of hyaluronan synthase (Has) and hyaluronidase (Hyal), which produce and digest HA, respectively.

STUDY DESIGN

Experimental prospective animal study.

METHODS

Vocal fold stripping was performed on 38 Sprague-Dawley rats. Vocal fold tissue was collected at five time points (3 days-2 months). Expression of HA was examined by immunohistochemistry, and messenger RNA (mRNA) expression of Has and Hyal was examined by real-time polymerase chain reaction and in-situ hybridization.

RESULTS

In scarred vocal folds, expression of Has1 and Has2 increased at day 3 together with expression of HA and returned to normal at 2 weeks. At 2 months, Has3 and Hyal3 mRNA showed higher expressions than normal.

CONCLUSIONS

Expression patterns of Has and Hyal genes differed between normal, acute-scarred, and chronic-scarred vocal folds, indicating the distinct roles of each enzyme in maintaining HA. Continuous upregulation of Has genes in the acute phase may be necessary to achieve scarless healing of vocal folds.

Structural and functional vocal fold epithelial integrity following injury

OBJECTIVES/HYPOTHESIS

An intact epithelium is an important part of vocal fold defense. Damage to the epithelium can compromise vocal fold homeostasis and protection of the host tissue from viral and bacterial invasion. Elucidating the effects of damage on epithelial architectural and barrier integrity provides insight into the role of epithelium in protecting vocal folds. Using an animal model, we evaluated the time course of structural and functional epithelial restoration following injury.

STUDY DESIGN

Prospective, controlled animal study.

METHODS

Forty rats underwent surgery to remove vocal fold mucosa unilaterally. Larynges were harvested at five time intervals between 3 to 90 days postinjury and were prepared for histological and permeability analyses.

RESULTS

Rapid restoration of structural integrity was demonstrated by return of a multilayerd epithelium, intercellular junctions, and basement membrane at 5 days postinjury. Atypical epithelial permeability was observed up to 5 weeks postinjury.

CONCLUSION

Restoration of epithelial barrier integrity lags epithelial structural restoration. Consequently, epithelial regeneration cannot be equated with return of functional barrier integrity. Rather, ongoing leakiness of regenerated epithelium indicates that vocal folds remain at risk for damage, pathogen invasion, and remodeling postinjury.

LEVEL OF EVIDENCE

N/A. Laryngoscope, 124:2764-2769, 2014.

Aerodynamic and acoustic effects of ventricular gap

PURPOSE

Supraglottic compression is frequently observed in individuals with dysphonia. It is commonly interpreted as an indication of excessive circumlaryngeal muscular tension and ventricular medialization. The purpose of this study was to describe the aerodynamic and acoustic impact of varying ventricular medialization in a canine model.

METHODS

Subglottal air pressure, glottal airflow, electroglottograph, acoustic signals, and high-speed video images were recorded in seven excised canine larynges mounted in vitro for laryngeal vibratory experimentation. The degree of gap between the ventricular folds was adjusted and measured using sutures and weights. Data were recorded during phonation when the ventricular gap was narrow, neutral, and large. Glottal resistance was estimated by measures of subglottal pressure and glottal flow.

RESULTS

Glottal resistance increased systematically as ventricular gap became smaller. Wide ventricular gaps were associated with increases in fundamental frequency and decreases in glottal resistance. Sound pressure level did not appear to be impacted by the adjustments in ventricular gap used in this research.

CONCLUSIONS

Increases in supraglottic compression and associated reduced ventricular width may be observed in a variety of disorders that affect voice quality. Ventricular compression may interact with true vocal fold posture and vibration resulting in predictable changes in aerodynamic, physiological, acoustic, and perceptual measures of phonation. The data from this report supports the theory that narrow ventricular gaps may be associated with disordered phonation. In vitro and in vivo human data are needed to further test this association.

Human embryonic stem cell-derived epithelial cells in a novel in vitro model of vocal mucosa

A satisfactory in vitro model of vocal fold mucosa does not exist, thus precluding a systematic, controlled study of vocal fold biology and biomechanics. We sought to create a valid, reproducible three-dimensional (3D) in vitro model of human origin of vocal fold mucosa of human origin. We hypothesized that coculture of human embryonic stem cell (hESC)-derived simple epithelial cells with primary vocal fold fibroblasts under appropriate conditions would elicit morphogenesis of progenitor cells into vocal fold epithelial-like cells and creation of a basement membrane. Using an in vitro prospective study design, hESCs were differentiated into cells that coexpressed the simple epithelial cell marker, keratin 18 (K18), and the transcription factor, p63. These simple epithelial cells were cocultured with primary vocal fold fibroblasts seeded in a collagen gel scaffold. The cells were cultured for 3 weeks in a keratinocyte medium at an air-liquid interface. After that time, the engineered mucosa demonstrated a stratified, squamous epithelium and a continuous basement membrane recapitulating the key morphologic and phenotypic characteristics of native vocal fold mucosa. hESC-derived epithelial cells exhibited positive staining for vocal fold stratified, squamous epithelial markers, keratin 13 (K13) and 14 (K14), as well as tight junctions, adherens junctions, gap junctions, and desmosomes. Despite the presence of components critical for epithelial structural integrity, the epithelium demonstrated greater permeability than native tissue indicating compromised functional integrity. While further work is warranted to improve functional barrier integrity, this study demonstrates that hESC-derived epithelial progenitor cells can be engineered to create a replicable 3D in vitro model of vocal fold mucosa featuring a multilayered, terminally differentiated epithelium.

[Treatment of glottal gap]

Glottal gaps can be either physiological or pathological. The latter are multifactorial, predominantly organic in origin and occasionally functional. Organic causes include vocal fold paralysis or scarring, as well as a deficiency or excess of tissue. In addition to loss of the mucosal wave, the degree of hoarseness is primarily determined by the circumferential area of the glottal gap. It is thus important to quantify the extent of glottal insufficiency. Although a patient's symptoms form the basis for treatment decisions, these may be subjective and inadequately reflected by the results of auditory-perceptual evaluation, voice analysis and voice performance tests. The therapeutic approach should always combine phonosurgery with conventional voice therapy methods. Voice therapy utilises all the resources made available by the sphincter model of the aerodigestive tract and knowledge on the mechanism of voice production. The aim of phonosurgery is medialization, reconstruction or reinnervation by injection laryngoplasty or larynx framework surgery. These different methods can be combined and often applied directly after vocal fold surgery (primary reconstruction). In conclusion, the techniques described here can be effectively employed to compensate for glottal gaps.

Laryngoscopy, stroboscopy and other tools for the evaluation of voice disorders

This article discusses and analyzes the diagnosis and management of voice disorders. Beginning with an insightful description of dysphonia as a sign and symptom rather than diagnosis, and an analysis of its unifying principles, the discussion continues with a review of evaluation, laryngoscopy, stroboscopy, and their respective advantages and disadvantages.

Local vascularized flaps for augmentation of Reinke's space

OBJECTIVES/HYPOTHESIS

The purpose of this study is to describe and test a novel surgical strategy for augmentation of Reinke's space using vascularized flaps: a thyroid ala perichondrium flap (TAP) and a composite thyroid ala perichondrium flap (CTAP) from the anterior larynx. We hypothesized that these specially designed vascularized flaps would remain viable once inset into the lamina propria, and that they would not disrupt rheologic, biomechanical, and histologic properties of the native vocal fold.

STUDY DESIGN

Experimental. In vivo canine model.

METHODS

The length and volume of test flaps harvested in six adult human cadaveric larynges were analyzed to determine suitability for use in augmentation in the lamina propria. Also, 12 beagles randomly underwent unilateral placement of either TAP or CTAP, which were designed in accordance with the human adult cadaveric experiments. Flap perfusion was measured before and after harvest with laser Doppler. After 1 month, the beagles were humanely sacrificed and their larynges subjected to aerodynamic and acoustic evaluation using an excised larynx apparatus. The vocal fold lamina propria of four larynges--two TAP and two CTAP--underwent rheologic evaluation using a simple-shear rheometer. The remaining eight larynges underwent quantitative histologic and immunohistochemical evaluation. The survival and complication (swallowing, airway, local wound) rates of all dogs were noted.

RESULTS

Initial studies with adult human cadaveric larynges established that TAP and CTAP possessed length and volume greater than native lamina propria. In the canine experiments, the perfusion change in the flaps was similar between flap groups. The damping ratio (ζ), dynamic viscosity (η'), elastic shear modulus (G'), and viscous shear modulus (G″) of treated and untreated native vocal folds were not statistically different. The glottic function measures of vocal efficiency, laryngeal resistance, jitter, shimmer, and harmonics-to-noise ratio (HNR) of treated and normal larynges were not statistically different. Similarly, the values for collagen, elastin, and glycosaminoglycans (GAGs) in treated and untreated vocal folds were not statistically different. Also, neither neochrondrogenesis nor neoosteogenesis was detected in any treated vocal fold. The values for vascular and cellular proliferation in treated and untreated vocal folds were not statistically different. All test dogs survived and had no complications related to swallowing, airway distress, or the local wound.

CONCLUSIONS

The test flaps described and tested in this study appear to have conceptually attractive features for augmentation of Reinke's space. When placed in an in vivo setting TAP and CTAP did not reveal unfavorable vascular, rheologic, aerodynamic, acoustic, or histologic characteristics. There was no unanticipated morbidity or mortality to the test animals. Long-term viability of these flaps is unknown. TAP and CTAP may open novel pathways for correction of glottic defects and may offer crossover opportunities with tissue engineering techniques.

Effects of basic fibroblast growth factor on rat vocal fold fibroblasts

OBJECTIVES

The overarching goal of this line of research is to translate basic fibroblast growth factor (bFGF) treatment for vocal fold scarring into practical clinical use. In a previous canine investigation, we demonstrated that bFGF improves phonation threshold pressure, mucosal wave amplitude, and histologic measures in vocal folds treated after injury. In the present study, we studied the effects of bFGF on gene expression of the extracellular matrix and growth factors in rat vocal fold fibroblasts.

METHODS

Fibroblasts harvested from the vocal folds of 5 rats were treated with 3 concentrations of bFGF (0, 10, and 100 ng/mL). The fibroblasts were collected at 24 hours and 72 hours after bFGF administration. Quantitative polymerase chain reaction was then used to investigate the gene expression of the investigated growth factors and extracellular matrices.

RESULTS

The results revealed significantly down-regulated expression of procollagen I and significantly up-regulated expression of hyaluronic acid synthase (HAS) 2 and fibronectin in fibroblasts treated with bFGF. The administration of bFGF also resulted in the up-regulation of bFGF and hepatocyte growth factor (HGF). No changes in the expression of HAS-1, tropoelastin, or procollagen III were observed between the treatment and control conditions.

CONCLUSIONS

Treatment with bFGF induces the down-regulation of procollagen I and the up-regulation of HAS-2 in vocal fold fibroblast cell cultures. These gene expression alterations to key mediators of the wound healing process may translate into potential benefits in the remediation of vocal fold injury. The up-regulation of HGF, an antifibrotic effector molecule, may demonstrate additional benefits by optimizing the wound healing environment and by accelerating the wound repair cascade. These findings may provide fuel for additional discoveries into the development of growth factor therapy for the treatment of vocal fold scar.

Clinical applications of mesenchymal stem cells in laryngotracheal reconstruction

During the past several years, mesenchymal stem cells (MSCs) derived from adult tissue have rapidly moved from in vitro and animal studies into clinical trials as a therapeutic modality for a diverse group of clinical applications, including head and neck reconstruction. For many diseases, cell therapy could affect the underlying pathophysiologic processes through multiple pathways providing an advantage over current treatment modalities. There is an emerging body of evidence that MSCs have unique immunomodulatory properties in addition to the ability to differentiate into multiple tissue lineages which make them even more attractive for regenerative medicine. A variety of pre-clinical and clinical studies have shown that MSCs may have a useful role in tissue repair as well as engineering strategies in head and neck reconstructive surgery. Clinically, this has ranged from injection laryngoplasty to the implantation of a tracheal construct seeded with MSC-derived chondrocytes. Recent advances in stem cell immunobiology can offer insight to the multiple mechanisms through which MSCs could affect underlying pathophysiologic processes ranging from vocal fold scarring to composite tissue defects. Thorough evaluation of the current literature is necessary in understanding how MSCs could potentially revolutionize our approach to head and neck defects. The purpose of this review is to highlight the advances in MSC-based therapies in head and neck surgery, specifically laryngotracheal reconstruction. The clinical role of tissue-derived MSCs, though not well understood, holds promise for many therapeutic applications in regenerative medicine and reconstruction.