Comparative Treatment Outcomes for Idiopathic Subglottic Stenosis: 5-Year Update.

The North American Airway Collaborative (NoAAC) previously published a 3-year multi-institutional prospective cohort study showing variation in treatment effectiveness between 3 primary surgical techniques for idiopathic subglottic stenosis (iSGS). In this report, we update these findings to include 5 years of data evaluating treatment effectiveness. Patients in the NoAAC cohort were re-enrolled for 2 additional years and followed using the prespecified published protocol. Consistent with prior data, prospective observation of 487 iSGS patients for 5 years showed treatment effectiveness differed by modality. Cricotracheal resection maintained the lowest rate of recurrent operation (5%), followed by endoscopic resection with adjuvant medical therapy (30%) and endoscopic dilation (50%). These data support the initial observations and continue to provide value to providers and patients navigating longitudinal decision-making. Level of evidence: 2-prospective cohort study.

Acoustic Screening of the "Wet voice": Proof of Concept in an ex vivo Canine Laryngeal Model.

BACKGROUND: Current protocols for bedside swallow evaluation have high rates of false negative results. Though experts are not consistently able to screen for aspiration risk by assessing vocal quality, there is emerging evidence that vocal acoustic parameters are significantly different in patients at risk of aspiration. Herein, we aimed to determine whether the presence of material on the vocal folds in an excised canine laryngeal model may have an impact on acoustic and aerodynamic measures. METHODS: Two ex vivo canine larynges were tested. Three liquids of different viscosities (1:100 diluted glycerin, pure glycerin, and honey-thick Varibar) were placed on the vocal folds at a constant volume. Acoustic and aerodynamic measures were obtained in both adducted and abducted vocal fold configurations. Intraglottal high-speed imaging was used to approximate the maximum divergence angle of the larynges in the studied conditions and examine its relationship to vocal efficiency (VE) and acoustic measures. RESULTS: In glottic insufficiency conditions only, we found that several acoustic parameters could predict the presence of material on the vocal folds. Based on the combination of the aerodynamic and acoustic data, we found that decreased spectral energy in the higher harmonics was associated with decreased VE in the presence of material on the vocal folds and/or glottic insufficiency. CONCLUSION: Decreased spectral energy in the higher harmonics of the voice was found to be a potential biomarker of swallowing dysfunction, as it correlates with decreased vocal efficiency due to material on the vocal folds and/or glottic insufficiency, both of which are known risk factors for aspiration. LEVEL OF EVIDENCE: NA Laryngoscope, 133:2517-2524, 2023.

Surgical Treatment of Acquired Velopharyngeal Insufficiency in Adults With Dysphagia and Dysphonia.

OBJECTIVES: Velopharyngeal insufficiency (VPI) is a form of velopharyngeal dysfunction caused by abnormal or insufficient anatomy. This process is known to be associated with dysphagia and dysphonia but surgical interventions for these complex patients have not been well studied. The current study characterized a small cohort of adult patients with acquired VPI, dysphonia, and dysphagia, as well as associated surgical interventions. METHODS: A retrospective descriptive case series of 22 (N = 22) adult patients over a 6-year period with acquired VPI and varying degrees of dysphagia and dysphonia was described from a multi-disciplinary voice and swallowing clinic. Perceptual assessment, nasopharyngoscopy, fluoroscopic swallowing assessment, and patient reported outcomes were reviewed to characterize the cohort. RESULTS: VPI etiologies included: stroke (n = 4), head and neck cancer (n = 5), brainstem lesions (n = 5), trauma (n = 5), and other/unknown (n = 3). All 22 patients underwent nasopharyngoscopy and were categorized as having unilateral (n = 13), central (n = 4), or no (n = 5) velopharyngeal deficits. Seventeen patients (77.2%) underwent modified barium swallow studies, revealing that soft palate elevation scored least impaired among patients with no VPI, and most impaired among patients with unilateral VPI deficits. All 22 patients underwent some form of surgical intervention for VPI, with 14 (63.6%) of those patients requiring additional surgical revision. CONCLUSION: This series is one of the first to the authors' knowledge to characterize a cohort of individuals with VPI, dysphagia, and dysphonia and associated surgical interventions.

Computational Modeling of Voice Production Using Excised Canine Larynx.

A combined experimental-numerical work was conducted to comprehensively validate a subject-specific continuum model of voice production in larynx using excised canine laryngeal experiments. The computational model is a coupling of the Navier-Stokes equations for glottal flow dynamics and a finite element model of vocal fold dynamics. The numerical simulations employed a cover-body vocal fold structure with the geometry reconstructed from magnetic resonance imaging scans and the material properties determined through an optimization-based inverse process of experimental indentation measurement. The results showed that the simulations predicted key features of the dynamics observed in the experiments, including the skewing of the glottal flow waveform, mucosal wave propagation, continuous increase of the divergent angle and intraglottal swirl strength during glottal closing, and flow recirculation between glottal jet and vocal fold. The simulations also predicted the increase of the divergent angle, glottal jet speed, and intraglottal flow swirl strength with the subglottal pressure, same as in the experiments. Quantitatively, the simulations over-predicted the frequency and jet speed and under-predicted the flow rate and divergent angle for the larynx under study. The limitations of the model and their implications were discussed.

Association of Social Determinants of Health with Time to Diagnosis and Treatment Outcomes in Idiopathic Subglottic Stenosis.

OBJECTIVES: To examine whether social determinants of health (SDH) factors are associated with time to diagnosis, treatment selection, and time to recurrent surgical intervention in idiopathic subglottic stenosis (iSGS) patients. METHODS: Adult patients with diagnosed iSGS were recruited prospectively (2015-2017) via clinical providers as part of the North American Airway Collaborative (NoAAC) and via an online iSGS support community on Facebook. Patient-specific SDH factors included highest educational attainment (self-reported), median household income (matched from home zip code via U.S. Census data), and number of close friends (self-reported) as a measure of social support. Main outcomes of interest were time to disease diagnosis (years from symptom onset), treatment selection (endoscopic dilation [ED] vs cricotracheal resection [CTR] vs endoscopic resection with adjuvant medical therapy [ERMT]), and time to recurrent surgical intervention (number of days from initial surgical procedure) as a surrogate for disease recurrence. RESULTS: The total 810 participants were 98.5% female, 97.2% Caucasian, and had a median age of 50 years (IQR, 43-58). The cohort had a median household income of $62 307 (IQR, $50 345-$79 773), a median of 7 close friends (IQR, 4-10), and 64.7% of patients completed college or graduate school. Education, income, and number of friends were not associated with time to diagnosis via multivariable linear regression modeling. Univariable multinominal logistic regression demonstrated an association between education and income for selecting ED versus ERMT, but no associations were noted for CTR. No associations were noted for time to recurrent surgical procedure via Kaplan Meier modeling and Cox proportional hazards regression. CONCLUSIONS: Patient education, income, and social support were not associated with time to diagnosis or time to disease recurrence. This suggests additional patient, procedure, or disease-specific factors contribute to the observed variations in iSGS surgical outcomes.

Medialization Laryngoplasty: A Review for Speech-Language Pathologists.

Purpose The purpose of this study is to familiarize speech-language-pathologists with the current state of the science regarding medialization laryngoplasty in the treatment of voice disorders, with emphasis on current evidence-based practice, voice outcomes, and future directions for research. Method A literature review was performed in PubMed and Embase using the keywords vocal fold/cord and laryngoplasty, thyroplasty, augmentation, or laryngeal framework. Articles published between 2010 and 2020 were reviewed for data about clinical applications, technical approach, voice-related outcomes, and basic science or clinical innovations with the potential to improve patient care. A synthesis of data was performed from articles meeting the outlined search criteria. Conclusions As key members in the multidisciplinary care of voice disorders, speech-language pathologists need to be informed of current research in medialization laryngoplasty, a procedure commonly used for patients with glottic insufficiency. Advances in anesthetic technique, office-based procedures, and the development of materials with increased bio-tolerability over the past decade have led to innovations in treatment and improved patient outcomes. Recent applications of computational and bioengineering approaches have the potential to provide new directions in the refinement of currently available techniques and the improvement of patient-based treatment outcomes.

Impact of Vertical Stiffness Gradient on the Maximum Divergence Angle.

INTRODUCTION: During vocal fold vibration, the medial surface of both folds forms a convergent shape during opening and a divergent shape during closing. A greater maximum divergence angle is associated with greater closing forces which will increase the closing speed of the glottis. An increased closing speed results in a greater acoustic intensity and greater vocal efficiency. Indentation testing showed that as the strain increases, the inferior aspect of the folds becomes stiffer than the superior aspect, resulting in the vertical stiffness gradient (VSG). We hypothesize that a reduction of the vertical stiffness gradient will reduce the maximum divergence angle. METHODS: Four excised canine larynges were tested. Stress-strain curves of the superior and inferior aspects of the fold in the mid membranous plane of the baseline larynges were taken using the indentation method. Calcium hydroxylapatite (CaHA) crystals were then injected into the superior aspect of the fold. The stress-strain tests were repeated. Particle imaging velocimetry (PIV) of the intraglottal velocity fields was performed in three larynges at different subglottal pressures in the mid coronal plane for the baseline and CaHA-injected larynges. RESULTS: CaHA injection reduced the inferior-superior stiffness gradient in all larynges. The maximal divergence angle was markedly reduced. In some cases, there was not a divergent angle. DISCUSSION: Marked reduction of the vertical stiffness gradient significantly reduces the maximum divergence angle. Clinical implications will be discussed. LEVEL OF EVIDENCE: NA Laryngoscope, 131:E1934-E1940, 2021.

Predicting No Show in Voice therapy: Avoiding the Missed Appointment Cycle.

INTRODUCTION: Voice therapy plays a critical role in the treatment of voice disorders. Despite positive outcomes in patients who attend voice therapy, otolaryngologists, and speech-language pathologists continue to struggle with patient compliance. Previous studies evaluating the multidisciplinary clinic model have shown better completion, VHI-10 scores, and fewer cancelation and no-shows (NS). We sought to review our own patient experience to better identify factors that predict NS rates in voice therapy. METHODS: A retrospective chart review of patients at a tertiary medical center were included if they had a scheduled appointment during a 6-month period that was cancelled or a NS. Charts were reviewed for age, gender, race, diagnosis, number of sessions attended, reason for discharge, and attending physician. NS percentage is calculated as a ratio of number cancellations to total number sessions scheduled. A multivariable general linear model was used to examine the association between NS and the listed covariates. FINDINGS: The study included 146 patients mean (SD) age 52.7 (16.6), where 62% were female and 72.6% were white. There is evidence that not being seen in a multidisciplinary clinic is significantly associated with NS rates in voice therapy (χ2 = 4.09, P = 0.0431). There is also evidence that non-white race is significantly associated with NS rates in voice therapy (χ2 = 11.76, P = 0.0006). CONCLUSIONS: Data presented in this study further support the use of a multidisciplinary model to improve NS rates in voice therapy. The relationship between nonwhite patients and lower NS suggests another determining factor in nonadherence to voice therapy.

Quantification of the Intraglottal Pressure Induced by Flow Separation Vortices Using Large Eddy Simulation.

The greatest rate of change in the glottal flow rate during phonation is a rapid decrease that occurs during the latter part of the glottal closing. Previous works showed that intraglottal flow separation vortices form in a divergent glottis, produce negative gauge pressures (below atmospheric) during closing. It is hypothesized here that flow separation vortices contribute to the rapid closing mechanism of the true vocal folds during phonation. Four idealized static models (M5) of the human larynx were investigated using large eddy simulation: 2 models featured parallel folds that did not enable flow separation in the glottis and 2 models involved a divergent glottis. The influence of the ventricular gap (narrow/wide) is evaluated. An unsteady pressure inlet representing a voicing cycle was applied to the sub-glottal region to mimic the time-varying glottal flow. Intraglottal vortex structures formed downstream of the separation point in a divergent glottis. Their existence caused a higher closing force that was applied onto the vocal folds. A narrow ventricular gap strengthens this effect. Strength of the intraglottal vortices increased with the maximum flow declination rate. Therefore, a more divergent shape of the glottis during glottal closing will be one of the main contributors to the voice quality.

Volume velocity in a canine larynx model using time­resolved tomographic particle image velocimetry.

In the classic source-filter theory, the source of sound is flow modulation. "Flow" is the flow rate (Q) and flow modulation is dQ/dt. Other investigators have argued, using theoretical, computational, and mechanical models of the larynx, that there are additional sources of sound. To determine the acoustic role of dQ/dt in a tissue model, Q needs to be accurately measured within a few millimeters of the glottal exit; however, no direct measures of Q currently exist. The goal of this study is to obtain this waveform in an excised canine larynx model using time-resolved tomographic particle image velocimetry. The flow rate data are captured simultaneously with acoustic measurements to determine relations with vocal characteristics. The results show that glottal waveform characteristics such as maximum flow declination rate are proportional to the subglottal pressure, fundamental frequency, and acoustic intensity. These findings are important as they use direct measurements of the volume flow at the glottal exit to validate some of the assumptions used in the source-filter theory. In addition, future work will address the accuracy of indirect clinical measurement techniques, such as the Rothenberg mask.

Comparative Treatment Outcomes for Patients With Idiopathic Subglottic Stenosis.

Importance: Surgical treatment comparisons in rare diseases are difficult secondary to the geographic distribution of patients. Fortunately, emerging technologies offer promise to reduce these barriers for research. Objective: To prospectively compare the outcomes of the 3 most common surgical approaches for idiopathic subglottic stenosis (iSGS), a rare airway disease. Design, Setting, and Participants: In this international, prospective, 3-year multicenter cohort study, 810 patients with untreated, newly diagnosed, or previously treated iSGS were enrolled after undergoing a surgical procedure (endoscopic dilation [ED], endoscopic resection with adjuvant medical therapy [ERMT], or cricotracheal resection [CTR]). Patients were recruited from clinician practices in the North American Airway Collaborative and an online iSGS community on Facebook. Main Outcomes and Measures: The primary end point was days from initial surgical procedure to recurrent surgical procedure. Secondary end points included quality of life using the Clinical COPD (chronic obstructive pulmonary disease) Questionnaire (CCQ), Voice Handicap Index-10 (VHI-10), Eating Assessment Test-10 (EAT-10), the 12-Item Short-Form Version 2 (SF-12v2), and postoperative complications. Results: Of 810 patients in this cohort, 798 (98.5%) were female and 787 (97.2%) were white, with a median age of 50 years (interquartile range, 43-58 years). Index surgical procedures were ED (n = 603; 74.4%), ERMT (n = 121; 14.9%), and CTR (n = 86; 10.6%). Overall, 185 patients (22.8%) had a recurrent surgical procedure during the 3-year study, but recurrence differed by modality (CTR, 1 patient [1.2%]; ERMT, 15 [12.4%]; and ED, 169 [28.0%]). Weighted, propensity score-matched, Cox proportional hazards regression models showed ED was inferior to ERMT (hazard ratio [HR], 3.16; 95% CI, 1.8-5.5). Among successfully treated patients without recurrence, those treated with CTR had the best CCQ (0.75 points) and SF-12v2 (54 points) scores and worst VHI-10 score (13 points) 360 days after enrollment as well as the greatest perioperative risk. Conclusions and Relevance: In this cohort study of 810 patients with iSGS, endoscopic dilation, the most popular surgical approach for iSGS, was associated with a higher recurrence rate compared with other procedures. Cricotracheal resection offered the most durable results but showed the greatest perioperative risk and the worst long-term voice outcomes. Endoscopic resection with medical therapy was associated with better disease control compared with ED and had minimal association with vocal function. These results may be used to inform individual patient treatment decision-making.

Cervical slide tracheoplasty in adults with laryngotracheal stenosis.

OBJECTIVES: 1) Evaluate success rates for adults undergoing cervical slide tracheoplasty. 2) Examine complication rates of slide tracheoplasty in adults. METHODS: A retrospective cohort of adults > 21 years of age undergoing cervical slide tracheoplasty for tracheal stenosis between October 2011 and August 2017 was reviewed. Comorbidities, stenosis grade, etiology of stenosis, primary versus revision surgery, complications, and number of adjunct endoscopic procedures required postoperatively were evaluated. RESULTS: Nineteen patients (63% female) underwent cervical slide tracheoplasty during the study period (median age 30 years, range 21-70). The most common etiology of stenosis was iatrogenic (68%), followed by congenital etiologies (26%). Fifty-eight percent of patients had undergone a previous open airway procedure. Thirty-nine percent were tracheostomy-dependent prior to surgery, and the remainder had severe exercise intolerance. Sixty-three percent were successfully extubated on the operating room table at the end of the procedure. Six (32%) patients experienced surgical complications, including one anastomotic dehiscence, three neck abscesses requiring incision and drainage (I&D), and replacement of adjunctive airway device in two patients. Seventy percent of the patients required ≥ 1 endoscopic dilation in the first 12 months following surgery, with a median of one (range 1-8) procedure. At most recent follow-up (median 8 months, range 4-64 months), 18 of 19 (95%) of patients had minimal airway symptoms without need for tracheostomy. The one patient who was not decannulated expired of a presumed cardiac event prior to decannulation. CONCLUSION: Cervical slide tracheoplasty is an excellent reconstructive option for adult patients with tracheal stenosis, including those with history of previous airway reconstruction. LEVEL OF EVIDENCE: 4 Laryngoscope, 129:818-822, 2019.

Office-based esophageal dilation in head and neck cancer: Safety, feasibility, and cost analysis.

OBJECTIVE: To review experience, safety, and cost of office-based esophageal dilation in patients with history of head and neck cancer (HNCA). METHODS: The medical records of patients undergoing esophageal dilation in the office were retrospectively reviewed between August 2015 and May 2017. Patients were given nasal topical anesthesia. Next, a transnasal esophagoscopy (TNE) was performed. If the patient tolerated TNE, we proceeded with esophageal dilation using Seldinger technique with the CRE™ Boston Scientific (Boston Scientific Corp., Marlborough, MA) balloon system. Patients were discharged directly from the outpatient clinic. RESULTS: Forty-seven dilations were performed in 22 patients with an average of 2.1 dilations/patient (range 1-10, standard deviation [SD] ± 2.2). Seventeen patients (77%) were male. The average age was 67 years (range 35-78 years, SD ± 8.5). The most common primary site of cancer was oral cavity/oropharynx (n = 10), followed by larynx (n = 6). All patients (100%) had history of radiation treatment. Four patients were postlaryngectomy. The indication for esophageal dilation was esophageal stricture and progressive dysphagia. All dilations occurred in the proximal esophagus. There were no major complications. Three focal, superficial lacerations occurred. Two patients experienced mild, self-limited epistaxis. One dilation was poorly tolerated due to discomfort. One patient required pain medication postprocedure. Office-based esophageal dilation generated $15,000 less in health system charges compared to traditional operating room dilation on average per episode of care. CONCLUSION: In patients with history of HNCA and radiation, office-based TNE with esophageal dilation appears safe, well-tolerated, and cost-effective. In a small cohort, the technique has low complication rate and is feasible in an otolaryngology outpatient office setting. LEVEL OF EVIDENCE: 4. Laryngoscope, 128:2261-2267, 2018.

Computational study of false vocal folds effects on unsteady airflows through static models of the human larynx.

Compressible large eddy simulation is employed to numerically investigate the laryngeal flow. Symmetric static models of the human larynx with a divergent glottis are considered, with the presence of false vocal folds (FVFs). The compressible study agrees well with that of the incompressible study. Due to the high enough Reynolds number, the flow is unsteady and develops asymmetric states downstream of the glottis. The glottal jet curvature decreases with the presence of FVFs or the ventricular folds. The gap between the FVFs stretches the flow structure and reduces the jet curvature. The presence of FVFs has a significant effect on the laryngeal flow resistance. The intra-glottal vortex structures are formed on the divergent wall of the glottis, immediately downstream of the separation point. The vortices are then convected downstream and characterized by a significant negative static pressure. The FVFs are a main factor in the generation of stronger vortices, and thus on the closure of the TVFs. The direct link between the FVFs geometry and the motion of the TVFs, and by extension to the voice production, is of interest for medical applications as well as future research works. The presence of the FVFs also changes the dominant frequencies in the velocity and pressure spectra.

Gender and age in benign vocal fold lesions.

OBJECTIVE/HYPOTHESIS: Certain lesions appear to occur predominantly in one gender or in younger or older patients. We examined a large sample from a treatment-seeking population to describe gender and age associations of an array of benign vocal fold lesions. STUDY DESIGN: Retrospective review. METHODS: The medical records and evaluations of all adult patients presenting for care over a 5-year period were examined for demographic characteristics and lesion type. A total of 641 lesions in 602 patients were grouped into 13 broad categories, and prevalence was compared between male and female patients and three age groups. RESULTS: Pseudocysts and bilateral midfold lesions occurred principally in young (18-39 years old) females (P < 0.0001). Reinke's edema was found in older (> 39 years old) women (P < 0.012). Polyps, contact lesions, leukoplakia (all P < 0.0001), and sulcus (P < 0.0002) were found predominantly in men. CONCLUSION: Certain benign mucosal lesions are strongly associated with age and especially with gender. These differences may be explained by intrinsic differences in laryngeal anatomy and phonatory physiology in these groups, including differences in phonatory frequency and air pressure, and in the ability of the membranous vocal fold to withstand phonotrauma. Such inherent differences have implications for treatment expectations and approaches.

Unsteady laryngeal airflow simulations of the intra-glottal vortical structures.

The intra-glottal vortical structures developed in a static divergent glottis with continuous flow entering the glottis are characterized. Laryngeal airflow calculations are performed using the Large Eddy Simulation approach. It has been shown that intra-glottal vortices are formed on the divergent wall of the glottis, immediately downstream of the separation point. Even with non-pulsatile flow entering the glottis, the vortices are intermittently shed, producing unsteady flow at the glottal exit. The vortical structures are characterized by significant negative static pressure relative to the ambient pressure. These vortices increase in size and strength as they are convected downstream by the flow due to the entrained air from the supra-glottal region. The negative static pressures associated with the intra-glottal vortical structures suggest that the closing phase during phonation may be accelerated by such vortices. The intra-glottal negative pressures can affect both vocal fold vibration and voice production.