Faculty Bibliography

OBJECTIVES/HYPOTHESIS: Inhalation injury significantly increases morbidity and mortality in burn patients. Approximately one in five burn patients have acute injury to the larynx, trachea, and/or lungs-and as many as 70% have long-term laryngeal abnormalities. Although inhalation injury to the lung has been studied extensively, no models exist to study these insults to the larynx. As such, we developed an in vivo rabbit model to create precise and reproducible laryngeal burn with resultant tissue damage as a foundation for interventional studies. METHODS: Following tubeless tracheotomy, a custom temperature-control device was employed to apply heated air (70 degrees C-80 degrees C, 150 degrees C-160 degrees C, or 310 degrees C-320 degrees C) +/- smoke derived from unbleached cotton to the larynx, endoscopically, minimizing adjacent tissue damage in six rabbits. Pain, nutrition, and level of activity were monitored. Direct laryngoscopy and histological examination were performed 24 hours following insult. RESULTS: All animals survived injury with appropriate pain control; oral intake was initiated and all were adequately ventilating via tracheostomy. Burn sequelae were noted under direct visualization 24 hours after injury, and graded levels of edema and tissue damage were observed as a function of temperature. Edema obstructed true vocal fold visualization at increased temperatures. These injury patterns correlated with graded tissue damage on histology. CONCLUSION: We created an in vivo model of laryngeal burn injury employing a custom burn device resulting in graded tissue injury. This model is critical for investigation of the mechanisms underlying burn injury, and ultimately, the development and evaluation of therapies for this challenging population. LEVEL OF EVIDENCE: N/A. Laryngoscope, 2016.

The vocal folds (VFs) are exposed to a number of injurious stimuli that frequently lead to aberrant structural alterations and altered biomechanical properties that clinically manifest as voice disorders. Therapies to restore both structure and function of this delicate tissue are ideal. However, such methods have not been adequately developed. Our group and others hypothesize that tissue engineering and regenerative medicine approaches, previously described for other tissue systems, hold significant promise for the VFs. In the current review, we explore the concept of tissue engineering as it relates to the VFs as well as recent studies employing both naturally- and synthetically-derived biomaterials, including those from laryngeal and non-laryngeal sources, in combination with stem cells for a tissue-engineered approach to VF repair.

OBJECTIVE: To determine the prevalence and also accuracy of the laryngopharyngeal reflux (LPR) referring diagnosis and to determine the most useful clinical tool in arriving at the final diagnosis in a tertiary laryngology practice. STUDY DESIGN: Case series with planned data collection. SETTING: Six tertiary academic laryngology practices. SUBJECTS AND METHODS: We collected referring diagnosis and demographic information, including age, sex, ethnicity, referring physician, and whether or not patients had prior flexible laryngoscopy for 1077 patients presenting with laryngologic complaints from January 2010 and June 2013. Final diagnosis after the referred laryngologist's examination and the key diagnostic test used was then recorded. RESULTS: Of 1077 patients, 132 had a singular referring diagnosis of LPR. Only 47 of 132 patients (35.6%) had LPR confirmed on final primary diagnosis. Transnasal flexible laryngoscopy confirmed this in 27 of 47 (57.4%) patients. Eighty-five of 132 (64.4%) had a different final diagnosis than LPR. Sixty-five of 85 (76.5%) of these alternative pathologies were diagnosed with the aid of laryngeal stroboscopy. CONCLUSIONS: LPR appears to be an overused diagnosis for laryngologic complaints. For patients who have already had transnasal flexible laryngoscopic exams prior to their referral, laryngeal stroboscopy is the key diagnostic tool in arriving at the correct diagnosis.

The human vocal folds are complex structures made up of distinct layers that vary in cellular and extracellular composition. The mechanical properties of vocal fold tissue are fundamental to the study of both the acoustics and biomechanics of voice production. To date, quantitative methods have been applied to characterize the vocal fold tissue in both normal and pathologic conditions. This review describes, summarizes, and discusses the most commonly employed methods for vocal fold biomechanical testing. Force-elongation, torsional parallel plate rheometry, simple-shear parallel plate rheometry, linear skin rheometry, and indentation are the most frequently employed biomechanical tests for vocal fold tissues and each provide material properties data that can be used to compare native tissue to diseased or treated tissue. Force-elongation testing is clinically useful, as it allows for functional unit testing, while rheometry provides physiologically relevant shear data, and nanoindentation permits micrometer scale testing across different areas of the vocal fold as well as whole organ testing. Thoughtful selection of the testing technique during experimental design to evaluate a hypothesis is critical to optimize biomechanical testing of vocal fold tissues.

OBJECTIVES/HYPOTHESIS: To investigate the role of Smad3 as a regulator of transforming growth factor (TGF)-beta1-mediated cell activities associated with fibrosis in normal human vocal fold fibroblasts. We also sought to confirm the temporal stability of Smad3 knockdown via small inhibitor ribonucleic acid (siRNA). Vocal fold fibroblasts were employed to determine the effects of Smad3 knockdown on TGF-beta1-mediated migration and contraction, as well as regulation of connective tissue growth factor (CTGF). We hypothesized that Smad3 is an ideal candidate for therapeutic manipulation in vivo based on its role in fibrosis. STUDY DESIGN: In vitro. METHODS: Knockdown of Smad3 via siRNA was performed in our normal human vocal fold cell line. Three-dimensional collagen gel contraction and scratch assays were employed to determine the role of Smad3 on TGF-beta1-mediated contraction and migration, respectively. The role Smad3 in the induction of CTGF was characterized via sodium dodecyl sulfate polyacrylamide gel electrophoresis. The effects of Smad3 signaling on Smad7 messenger (m)RNA and protein were also quantified. RESULTS: Smad3 knockdown was temporally-stable up to 72 hours (P < 0.001), diminished TGF-beta1-mediated collagen gel contraction and migration, and blunted induction of CTGF, but it had no effect on TGF-beta1-mediated Smad7 mRNA or protein induction. CONCLUSION: Transforming growth factor-beta1 stimulated profibrotic cell activities in our cell line and these actions were largely reduced with Smad3 knockdown. These data provide continued support for therapeutic targeting of Smad3 for vocal fold fibrosis because it appears to regulate the fibrotic phenotype. LEVEL OF EVIDENCE: N/A. Laryngoscope, 2015.

OBJECTIVES/HYPOTHESIS: To optimize decellularization of porcine vocal folds (VF) and quantify human bone marrow-derived mesenchymal stem cell (BM-MSC) interactions with this matrix to provide a foundation for regenerative approaches to VF repair. STUDY DESIGN AND METHODS: Vocal folds were dissected from porcine larynges and three decellularization protocols were compared, each consisting of washes and mechanical agitations with different combinations of reagents. DNA content was analyzed via Quant-iT Picogreen assay and hematoxylin and eosin staining. Bone marrow-derived MSCs were then seeded onto the decellularized VF matrices. Morphology, metabolic activity, DNA content, and gene expression were assessed using LIVE/DEAD Cell Viability, alamarBlue Cell Viability Assay, Quant-iT Picogreen assay, and, respectively. RESULTS: The most successful decellularization protocol removed 95% DNA content within 1 day, compared to several days required for previously described protocols. Histology confirmed the retention of extracellular matrix (ECM) and its components, including glycosaminoglycans, collagen, and fibrin, while void of nuclear/cellular content. Decellularized scaffolds were then seeded with BM-MSCs. Similar DNA quantities were observed after 24 hours of seeding within the VF-ECM scaffold when compared to cells on tissue culture plastic (TCP). LIVE/DEAD staining of the seeded VF-ECM confirmed excellent cell viability, and the metabolic activity of BM-MSCs increased significantly on VF-ECM compared to TCP. Endoglin gene expression decreased, suggestive of differentiation. CONCLUSION: Porcine VFs can be efficiently decellularized within 5 hours using a combination of sodium deoxycholate and peracetic acid. Decellularized VF-ECM supported attachment and growth of human BM-MSCs, with evidence of differentiation. LEVEL OF EVIDENCE: N/A Laryngoscope, 2015.

We report a case of unilateral vocal fold immobility in a 57-year-old woman that occurred subsequent to a choking episode, which she resolved by removing impacted food with a finger sweep. Other than the unilateral immobility, no abnormality of the laryngeal mucosa or framework was detected on physical examination, laryngoscopy, and computed tomography. Weeks later, the patient underwent an unrelated surgical procedure necessitating laryngeal mask airway ventilation. When she emerged from the procedure, she noted full resolution of her voice symptoms. Office laryngoscopy confirmed the full return of vocal fold function. We discuss possible explanations for the return of function in the context of this unusual onset and resolution. We also review the literature regarding unilateral vocal fold immobility, including its etiology, presentation, workup, and treatment.

INTRODUCTION: In-office laryngeal procedures present an alternative to the risks and costs associated with general anesthesia. However, the inherent control afforded by the operative theater is decreased potentially increasing the risk of complications. Many patients undergoing these procedures have traditional surgical risk factors, such as antithrombotic (AT) medical therapy. We sought to quantify complication rates for in-office procedures as a function of AT therapy. METHODS: A retrospective review of 127 diverse, in-office laryngeal procedures was performed and patients were then stratified based on AT medication status and type of procedure. The primary dependent variables were intraoperative and postoperative complications. Additionally, in those patients undergoing procedures with the goal of voice improvement, Voice Handicap Index (VHI)-10 scores were used to quantify the success of the procedure as a function of AT therapy. RESULTS: Of the 127 procedures, 27 procedures (21.2%) involved patients on some form of AT agent that was not ceased for the procedure. Across all patients, no intraoperative complications were encountered, irrespective of therapeutic status. Three postoperative complications were noted; all in patients not on AT therapy. A statistically significant improvement in VHI-10 scores was noted across all patients, irrespective of AT status. CONCLUSIONS: AT medications do not appear to increase the risk of complications associated with in-office laryngeal procedures. Furthermore, AT therapy seemed to have no negative impact on the voice outcomes of patients undergoing procedures for voice improvement.

Flexible laryngoscopes are common outpatient surveillance tools. Cleansing of these scopes between patients must be quick, effective, and safe. One sterilant that largely meets these criteria is ortho-phthalaldehyde (OPA); however, infrequently, patients may develop allergic reactions to it. We present three cases of patients who developed significant allergic reactions following repeated laryngoscopic examinations. Subsequent intradermal allergy testing confirmed sensitivity to OPA. In addition, we reviewed the current literature, which includes 17 similar reactions reported in nine patients across disciplines. Allergic reaction to OPA is uncommon, but a potentially under-reported severe complication of repeated endoscopy. LEVEL OF EVIDENCE: NA Laryngoscope, 2015.