Outcome of a multimodality approach to the management of idiopathic subglottic stenosis

PD-L1 Acts Independently of PD-1 as a Marker of Pathologic Fibroblasts in Laryngotracheal Stenosis

OBJECTIVE

Laryngotracheal stenosis (LTS) describes fibrotic airway obstruction that is life-threatening without treatment. Targeted therapies are needed as an adjunct to surgical management. We have previously observed the upregulation of immune checkpoint programmed cell death (PD)-1 and its ligand, PD-L1, in patients with LTS. This study aims to determine whether PD-1 and PD-L1 play a role in the pathophysiology of LTS.

STUDY DESIGN

Basic science.

SETTING

Laboratory.

METHODS

Fibroblasts derived from the subglottic scar of 5 iSGS patients were cultured ex vivo with transforming growth factor β (TGFβ), PD-L1 agonist (PD-1), and PD-L1 blockade (anti-PD-L1). PD-L1, TGFβ receptor II (TGFβRII), and Collagen-1 expression were quantified by flow cytometry. A validated chemomechanical injury model of subglottic stenosis was applied in PD-1 knockout and wild-type (WT) mice, and subglottic thickening was assessed by histologic analysis.

RESULTS

TGFβ significantly increased the expression of PD-L1 and Collagen-1 in human airway scar fibroblasts (P < .05). PD-1 knockout mice demonstrated no significant difference in subglottic airway fibrosis compared to WT mice. Ex vivo PD-L1 modulation had no impact on fibroblast Collagen-1 expression. PD-L1 high-intensity fibroblasts expressed greater Collagen-1 and TGFβRII compared to PD-L1 low-intensity fibroblasts.

CONCLUSION

PD-1 knockout does not protect mice from the development of laryngotracheal fibrosis. However, its ligand, PD-L1 is highly expressed on pathologic fibroblasts unique to scar, characterized by high Collagen-1 and TGFβRII expression. PD-L1 is also upregulated in conjunction with Collagen-1 by TGFβ stimulation. PD-L1 may act independently of PD-1 to sensitize fibroblasts to TGFβ, suggesting direct targeting of PD-L1 may have therapeutic potential in LTS.

Symptom-Free Intervals Following Laser Wedge Excision for Recurrent Idiopathic Subglottic Stenosis

OBJECTIVE

Analyze the duration of symptom-free intervals following laser wedge excision (LWE) for recurrent idiopathic subglottic stenosis (iSGS). Secondary aim includes evaluating the influence of patient-related or disease factors.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary center.

METHODS

Review of iSGS patients who underwent LWE between 2002 and 2021. LWE patients without prior airway surgery were labeled LWE primary (LWEP) and those with prior history of dilation were labeled LWE secondary (LWES). A conditional frailty repeated events model was used to analyze the median time to recurrence (MTR) for each nth recurrence. Secondary analysis included stratification by use of medical therapy and initial preoperative characteristics of scar (Myer-Cotton grade, distance between the glottis and superior-most aspect of scar, DGS; length of scar, DL).

RESULTS

Two hundred and ten iSGS patients underwent LWE (131 LWEP, 79 LWES). The proportion of patients experiencing at least 1, 3, 6, and 12 recurrences, respectively, was 68.0% (n = 143), 40.7% (n = 85), 20.0% (n = 42), and 5.2% (n = 11). There was exponential time-shortening from the 1st to 12th recurrence (P < .0001). While MTR was 4.1 years after the first LWE, this fell to 2.8, 1.7, 1.0, and 0.7 years for the 2nd, 3rd, 6th, and 12th recurrences. Furthermore, LWEP patients experienced longer MTR than LWES counterparts within the first 6 recurrences (P < .01). There was no significant relationship between intersurgical interval and medication adherence, DL, DGS, or grade for recurrences beyond the first (P = .207, P = .20, P = .43, P = .16).

CONCLUSION

Symptom-free intervals in iSGS shorten with each subsequent recurrence and LWE. The difference in MTR between LWEP and LWES groups was significant within the first 6 recurrences with LWEP having longer MTR.

LEVEL OF EVIDENCE: 3

Idiopathic Subglottic Stenosis in Non-Caucasian Women

Objective

To characterize presentation, disease course, and treatment of idiopathic subglottic stenosis (iSGS) in non-Caucasian women and compare this cohort to the predominantly female, Caucasian patient cohorts identified in the literature.

Study Design

Retrospective review. Results are compared to systematic review of demographics.

Setting

Multiple California institutions from 2008 to 2021.

Methods

Patients with intubation within 2 years of disease or who met exclusion criteria listed in prior publications were excluded. A systematic review of iSGS patient demographics was also completed for comparison.

Results

Of 421 patients with iSGS, 58 self-identified as non-Caucasian women, with 50 ultimately included. Mean age of onset was 45.1 years old (95% confidence interval [CI], 41.5-48.8), and mean age at diagnosis was 47.2 years (95% CI, 43.6-50.7). Mean Charlson comorbidity index was 1.06 (n = 49, 95% CI, 0.69-1.44). At diagnosis, Cotton-Meyer severity scores (documented in n = 45) were Cotton-Myer (CM) I (28.9%), CM II (40%), and CM III (31.1%). Mean age at first endoscopic surgery was 47.7 (95% CI, 44.2-51.3) years. 64% experienced disease recurrence with a median of 11 months between their first and second surgery. Our systematic review identified 60 studies that reported demographic features in patients with iSGS. 95% of pooled patients were Caucasian, while other demographic features were similar to the current cohort.

Conclusion

The non-Caucasian population, almost 14% of this Californian cohort, does not differ from the majority Caucasian population detailed in contemporary literature. This cohort supports the presence of some racial and ethnic heterogeneity in this disease population.

Similarity Network Analysis of the Adaptive Immune Response in the Proximal Airway

OBJECTIVES

Recent immunologic study of the adaptive immune repertoire in the subglottic airway demonstrated high-frequency T cell clones that do not overlap between individuals. However, the anatomic distribution and antigenic target of the T cell repertoire in the proximal airway mucosa remain unresolved.

METHODS

Single-cell RNA sequencing of matched scar and unaffected mucosa from idiopathic subglottic stenosis patients (iSGS, n = 32) was performed and compared with airway mucosa from healthy controls (n = 10). T cell receptor (TCR) sequences were interrogated via similarity network analysis to explore antigenic targets using the published algorithm: Grouping of Lymphocyte Interactions by Paratope Hotspots (GLIPH2).

RESULTS

The mucosal T cell repertoire in healthy control airways consisted of highly expressed T cell clones conserved across anatomic subsites (trachea, bronchi, bronchioles, and lung). In iSGS, high-frequency clones were equally represented in both scar and adjacent non-scar tissue. Significant differences in repertoire structure between iSGS scar and unaffected mucosa was observed, driven by unique low-frequency clones. GLIPH2 results suggest low-frequency clones share targets between multiple iSGS patients.

CONCLUSION

Healthy airway mucosa has a highly conserved T cell repertoire across multiple anatomic subsites. Similarly, iSGS patients have highly expressed T cell clones present in both scar and unaffected mucosa. iSGS airway scar possesses an abundance of less highly expanded clones with predicted antigen targets shared between patients. Interrogation of these shared motifs suggests abundant adaptive immunity to viral targets in iSGS airway scar. These results provide insight into disease pathogenesis and illuminate new treatment strategies in iSGS.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:3245-3252, 2024.

Lipoaspirate Injection in Relapsing Idiopathic Subglottic Stenosis: Preliminary Results

OBJECTIVES

The management of idiopathic subglottic stenosis (iSGS) poses a clinical challenge due to high recurrence rates following both endoscopic and open approaches, often leading to tracheostomy. The activation of abnormal T-cells and cytokine pathways has been linked to iSGS pathogenesis. Autologous adipose tissue centrifugation yields lipoaspirate, offering optimal anti-inflammatory effects and biocompatibility widely utilized in various medical settings. This report presents the first 3 cases employing endoscopic dilation (ED) in combination with local lipoaspirate injection to address recurrent iSGS.

METHODS

A prospective observational study was conducted, involving multidisciplinary evaluation by the Tracheal Team at the University of Modena. Patients meeting specific criteria were directed to undergo ED + lipoaspirate injection.

RESULTS

Three patients fulfilled the inclusion criteria. The mean number of prior endoscopic procedures performed was 8. Endoscopic examination revealed 90% stenosis in patient A, 60% stenosis in patient B, and 60% stenosis in patient C. All patients presented inflammatory tissue or incipient granulations at the stenotic site, with an average time of 6 months between previous procedures. After 15 months, none of the patients required further procedures, and endoscopic examination revealed a significant reduction or disappearance of inflammatory tissue with a stable airway lumen.

CONCLUSIONS

The observed results are encouraging in terms of reducing local inflammation and halting stenosis progression, especially in cases of short-term relapsing iSGS.

In-depth analysis of pre- and postoperative functional outcome parameters in patients receiving laryngotracheal surgery

OBJECTIVES

Surgical treatment for airway stenosis necessitates personalized techniques based on the stenosis location and length, leading to favourable surgical outcomes. However, there is limited literature on functional outcomes following laryngotracheal surgery with an adequate number of patients.

METHODS

We conducted a retrospective analysis of patients who underwent laryngotracheal surgery at the Department of Thoracic Surgery, Medical University of Vienna, from January 2017 to June 2021. The study included standardized functional assessments before and after surgery, encompassing spirometry, voice measurements, swallowing evaluation and subjective patient perception.

RESULTS

The study comprised 45 patients with an average age of 51.9 ± 15.9 years, of whom 89% were female, with idiopathic being the most common aetiology (67%). Procedures included standard cricotracheal resection in 11%, cricotracheal resection with dorsal mucosal flap in 49%, cricotracheal resection with dorsal mucosal flap and lateral cricoplasty in 24% and single-stage laryngotracheal reconstruction in 16%. There were no in-hospital mortalities or restenosis cases during the mean follow-up period of 20.8 ± 13.2 months. Swallowing function remained intact in all patients. Voice evaluations showed a decrease in fundamental vocal pitch [203 (81-290) Hz vs 150 (73-364) Hz, P < 0.001] and dynamic voice range (23.5 ± 5.8 semitones vs 17.8 ± 6.7 semitones, P < 0.001). However, no differences in voice volume were observed (60.0 ± 4.1 dB vs 60.2 ± 4.8 dB, P = 0.788). The overall predicted voice profile changed from R0B0H0 to R1B0H1.

CONCLUSIONS

Laryngotracheal surgery proves effective in fully restoring breathing capacity while preserving vocal function. Even in cases of high-grade and complex airway stenosis necessitating laryngotracheal reconstruction, favourable functional outcomes can be achieved.

Reconstructive Surgery of the Laryngotracheal Junction

The laryngotracheal junction is an anatomical region with special pathophysiological features. This review presents clinical pictures and malformations that manifest pre-dilectively at this localisation in children and adolescents as well as in adults. The diagnostic procedure is discussed. The possibilities of surgical reconstruction are presented depending on the pathology and age of the patient.

Characterizing the T Cell Repertoire in the Proximal Airway in Health and Disease

OBJECTIVES

Recent translational scientific efforts in subglottic stenosis (SGS) support a disease model where epithelial alterations facilitate microbiome displacement, dysregulated immune activation, and localized fibrosis. Given the observed immune cell infiltrate in SGS, we sought to test the hypothesis that SGS cases possessed a low diversity (highly clonal) adaptive immune response when compared with healthy controls.

METHODS

Single cell RNA sequencing (scRNA-seq) of subglottic mucosal scar in iSGS (n = 24), iLTS (n = 8), and healthy controls (n = 7) was performed. T cell receptor (TCR) sequences were extracted, analyzed, and used to construct repertoire structure, compare diversity, interrogate overlap, and define antigenic targets using the Immunarch bioinformatics pipeline.

RESULTS

The proximal airway mucosa in health and disease are equally diverse via Hill framework quantitation (iSGS vs. iLTS vs. Control, p > 0.05). Repertoires do not significantly overlap between individuals (Morisita <0.02). Among iSGS patients, clonality of the TCR repertoire is driven by CD8+ T cells, and iSGS patients possess numerous TCRs targeting viral and intercellular pathogens. High frequency clonotypes do not map to known targets in public datasets.

CONCLUSION

SGS cases do not possess a lower diversity adaptive immune infiltrate when compared with healthy controls. Interestingly, the TCR repertoire in both health and disease contains a restricted number of high frequency clonotypes that do not significantly overlap between individuals. The target of the high frequency clonotypes in health and disease remain unresolved.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:1757-1764, 2024.

Bibliometric and visualized analysis of scientific publications on subglottic stenosis based on web of science core collection

BACKGROUND

Subglottic Stenosis (SGS), with increasing numbers of studies, is the most specific and common clinical type of Laryngotracheal Stenosis (LTS). There is rapid publication turnover with newer management introduced and expanding research field. To our knowledge, there is no bibliometric analysis of SGS yet.

METHODS

In August 2022, we performed a thorough search in the Web of Science Core Collection database using the word "subglottic stenosis," and "SGS." The 580 articles were arranged based on correlation. The collected articles were then analyzed with an assessment of relevant factors. Meanwhile, we analyzed the top 100 most-cited articles on SGS.

RESULTS

The frequency of publication on SGS has increased substantially over time. The USA has contributed the most articles (n = 301). Vanderbilt University published most of the articles among other institutions (n = 18). Laryngoscope topped the list of journals and has published 89 SGS-related articles. Research hotspots shift from surgical treatment to conservative management.

CONCLUSIONS

The SGS-related literature has grown rapidly in recent years. This study represents the first bibliometric analysis of scientific articles on SGS. Areas to improve in SGS research can be identified after this analysis of the most impactful articles on this topic.

The Evolution and Outcomes of the "Maddern Procedure" for the Treatment of Subglottic Stenosis

INTRODUCTION

A novel technique to treat subglottic stenosis, the "Maddern Procedure", has been gaining acceptance in academic centers. This study describes the technique in detail, as well as its evolution over the first 28 patients performed at an academic center.

METHODS

A prospective case-series, with descriptive technique modifications cataloged throughout the 6 years needed to accumulate the patient cohort with a minimum of 2 years of follow-up (11/2015-11/2021). Main outcomes examined included changes to surgical indications, complications, and post-operative outcomes as measured by validated measures of voice and breathing.

RESULTS

Complete resection of subglottic scaring was performed, at first transcervically (2 pts), then transorally (26 pts). Successful performance of the procedure occurred in all patients without complications, with either successful decannulation of previously existing tracheotomies, or removal of perioperative tracheotomies. Buccal grafts (8/26) replaced skin graft as the graft of choice. Although high subglottic disease was first thought to be a contraindication, superior results became evident in cases of high stenosis rather than disease that included the upper trachea, with 4/26 patients requiring subsequent tracheal resection or tracheal dilation. Of the 22 remaining patients, 19/22 had successful arresting of restenosis, with 2/22 undergoing subsequent cricotracheal resection, and 1/22 pts requiring subglottic dilation. Overall, 19/26 Maddern pts (73%) had objectively favorable outcomes, with 24/26 (92%) reporting that they would have undergone the procedure again.

CONCLUSION

Full-thickness mucosal resection and relining of the subglottis is a developing technique that is a safe, yet technically challenging procedure which addresses the recurrent nature of the disease.

LEVEL OF EVIDENCE

Level 4 (Case-series) Laryngoscope, 133:3100-3108, 2023.

Human Leukocyte Antigen Genotyping of Idiopathic Subglottic Stenosis

OBJECTIVE

Despite recent scientific inquiry, idiopathic subglottic stenosis (iSGS) remains an enigmatic disease. The consistent demographics of the affected population suggest genetic factors may contribute to disease susceptibility. Given the inflammation observed in the affected proximal airway mucosa, we interrogated disease association with human leukocyte antigen (HLA) polymorphisms. Polymorphisms in the HLA locus have previously been shown to influence individuals' susceptibility to distinct inflammatory diseases.

METHODS

High-resolution HLA typing of 37 iSGS patients was compared with 1,242,890 healthy Caucasian controls of European ancestry from the USA National Marrow Donor Program and 281 patients with granulomatosis with polyangiitis (GPA).

RESULTS

Complete HLA genotyping of an iSGS population showed no significant associations when compared to a North American Caucasian control population. Unlike GPA patients, iSGS was not associated with allele DPB1*04:01 nor did allele homozygosity correlate with disease severity.

CONCLUSIONS

There was not a detectable HLA association observed in iSGS. These results support the concept that iSGS possesses a distinct genetic architecture from GPA. If genetic susceptibility exists in iSGS, it likely lies outside the HLA locus.

LEVEL OF EVIDENCE

NA, basic science Laryngoscope, 133:2533-2539, 2023.

Laryngotracheal Reconstruction for Subglottic and Tracheal Stenosis

Laryngotracheal stenosis is the common endpoint for any process that results in the narrowing of the airway at the level of the glottis, subglottis, or trachea. Although endoscopic procedures are effective in opening the airway lumen, open resection and reconstruction can be necessary to reconstitute a functional airway. When resection and anastomosis are insufficient due to extensive length or location of the stenosis, autologous grafts can be used to expand the airway. Future directions in airway reconstruction include tissue engineering and allotransplantation.

Endoscopic management of adult subglottic stenosis: an alternative to open surgery

PURPOSE

Various surgical techniques could be used to treat subglottic stenosis (SGS). The aim of this study is to present our experience in endoscopic management of SGS and show the impact of symptoms' evaluation, clinical examination and spirometry in the therapeutic decision.

METHODS

Endoscopic treatment was performed in patients referred for SGS and consisted of CO₂ scar lysis associated with balloon dilation and concomitant steroids' injection for patients with grade II or higher on the mMRC (modified Medical Research Council) dyspnea scale associated with a DI (Dyspnea Index) score higher than 10/40 and objective stenosis equal or higher than grade II. The preoperative DI score, EDI (expiratory disproportion index) and voice parameters were compared to postoperative results. The mean interval between endoscopic procedures (IEP) was calculated and we looked for the evolution of the IEP during repeated procedures.

RESULTS

Nineteen patients were included. 35 dilations were performed. The mean IEP was 86 weeks. There was a significant decrease of the postoperative DI scores by 18.6 points ± 11 (SD). An important difference of 20.1 ± 13.5 (SD) was identified between the pre and postoperative EDI. Minimal changes occured in voice parameters.

CONCLUSIONS

Endoscopic treatment with CO₂ scar lysis associated with balloon dilation and concomitant steroids' injection is a safe, reliable and minimally invasive endoscopic procedure to treat SGS. Decision to treat has to be on an individual basis taking into account subjective symptoms including Dyspnea Index score and objective laryngoscopic findings and spirometry.

Comparison of Inhaled Drug Delivery in Patients With One- and Two-level Laryngotracheal Stenosis

OBJECTIVES/HYPOTHESIS

Laryngotracheal stenosis (LTS) is a functionally devastating condition with high respiratory morbidity and mortality. This preliminary study investigates airflow dynamics and stenotic drug delivery in patients with one- and two-level LTS.

STUDY DESIGN

A Computational Modeling Restropective Cohort Study.

METHODS

Computed tomography scans from seven LTS patients, five with one-level (three subglottic, two tracheal), and two with two-level (glottis + trachea, glottis + subglottis) were used to reconstruct patient-specific three-dimensional upper airway models. Airflow and orally inhaled drug particle transport were simulated using computational fluid dynamics modeling. Drug particle transport was simulated for 1-20 μm particles released into the mouth at velocities of 0 m/s, 1 m/s, 3 m/s, and 10 m/s for metered dose inhaler (MDI) and 0 m/s for dry powder inhaler (DPI) simulations. Airflow resistance and stenotic drug deposition in the patients' airway models were compared.

RESULTS

Overall, there was increased airflow resistance at stenotic sites in subjects with two-level versus one-level stenosis (0.136 Pa s/ml vs. 0.069 Pa s/ml averages). Subjects with two-level stenosis had greater particle deposition at sites of stenosis compared to subjects with one-level stenosis (average deposition 2.31% vs. 0.96%). One-level stenosis subjects, as well as one two-level stenosis subject, had the greatest deposition using MDI with a spacer (0 m/s): 2.59% and 4.34%, respectively. The second two-level stenosis subject had the greatest deposition using DPI (3.45%). Maximum deposition across all stenotic subtypes except one-level tracheal stenosis was achieved with particle sizes of 6-10 μm.

CONCLUSIONS

Our results suggest that patients with two-level LTS may experience a more constricted laryngotracheal airflow profile compared to patients with one-level LTS, which may enhance overall stenotic drug deposition.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:366-374, 2023.

The efficiency of endoscopic versus open surgical interventions in adult benign laryngotracheal stenosis: a meta-analysis

BACKGROUND

The optimal treatments for adult benign laryngotracheal stenosis presently remains controversial. The majority of the disadvantages of endoscopic interventions with high recurrence rate and open surgical therapy accompanied by sophisticated techniques, complication and mortality, highlights the dilemma of option for treatments.

PURPOSE

To compare endoscopic treatments with open surgical interventions in adult patients with benign laryngotracheal stenosis, analyze their clinical outcomes, recurrence, complication and mortality.

METHODS

In the meta-analysis, the databases including PubMed, Embase, Ovid and Web of Science were searched for studies reporting adult benign laryngotracheal stenosis, and clinical outcomes were compared. The duplicate publications, reviews, comments or letters, conference abstracts, case reports were excluded. The random effect model was used for calculating the pooled effect estimates.

RESULTS

Eight studies (1627 cases) referring to six retrospective and two prospective researches were ultimately included in the meta-analysis. The decreased risk estimates of recurrence rate in patients receiving open surgical interventions were detected, comparing with endoscopic interventions (P < 0.05). Subgroup analysis revealed that decreased risk estimates of restenosis rate were also observed in patients receiving open surgical interventions compared with endoscopic interventions (P < 0.05), based on prospective studies, Europe and America, < 2-year follow-up, laryngeal stenosis, stenotic length without inter-group difference or stenotic grade II alone. However, there were no statistically significant difference of recurrence rate between the two interventions (P > 0.05) based on retrospective studies, South Asia and Africa, ≥ 2-year follow-up, involving tracheal lesion, stenotic length with inter-group difference, or stenotic grades of I-IV. No notable difference in the incidence of complication or mortality were identified.

CONCLUSIONS

Open surgical interventions were more suitable for most laryngotracheal stenosis without contraindications. Endoscopic interventions are increasingly being used to treat simple laryngotracheal stenosis, as well as complex airway stenosis in carefully selected cases. Multi-center prospective randomized controlled trials should be conducted to search for the standard treatments for laryngotracheal stenosis.

Complications following laser wedge excision for idiopathic subglottic stenosis

OBJECTIVES

Endoscopic laser wedge excision (LWE) is an effective treatment option for idiopathic subglottic stenosis (iSGS); however, data regarding complications following LWE are limited. The aim of the following analysis was to provide a review of frequency and type of complications that occur with LWE in patients with iSGS.

STUDY DESIGN

Retrospective review.

METHODS

Patients with iSGS undergoing LWE between January 2002 and September 2021 were performed. Demographic data were recorded. Complications were stratified into major and minor categories. The frequency of these complications and the respective treatment for them was analyzed.

RESULTS

212 patients within the study period underwent a total of 573 LWE procedures. All but two patients were female, with a median age of 54 years at time of LWE. Of these patients, 43 (20 %) patients experienced a complication. Of these, only 7 (15 %) of the reported complications were considered major while the rest were minor in nature. Major complications included 3 cases of post-operative hemoptysis, 1 case of tracheitis, and 3 cases of reduced vocal fold hypomobility with concurrent glottic stenosis. Minor complications consisted of 2 cases of tooth fracture and 34 cases of tongue paresthesia post-operatively that was self-limited. There were no mortalities.

CONCLUSION

Major complications occur in <5 % of LWE procedures based off the analysis. All major complications were managed without significant long-term morbidity. Minor complications with the LWE are self-limited in nature. Our data supports the LWE as a safe treatment option for iSGS.

LEVEL OF EVIDENCE: 4

Delayed Diagnosis of Idiopathic Subglottic Stenosis

OBJECTIVE

Idiopathic subglottic stenosis (iSGS) is a rare disease, causing life-threatening dyspnea secondary to scarring. Perhaps because it is rarely encountered, there is often a delay in diagnosing iSGS. The objective of this study is to characterize diagnostic delay of iSGS, factors that prolong delay, and its impact on iSGS patients.

STUDY DESIGN

Retrospective chart review.

METHODS

A retrospective chart review of 124 iSGS patients was performed. Times of symptom onset, presentation to otolaryngologist, diagnosis, imaging, pulmonary function testing (PFTs), surgeries, emergency department (ED) visits, and hospitalizations were recorded and univariate analyses were used to identify risk factors for delay.

RESULTS

The median total time to diagnosis from symptom onset was 24.5 months, with time to first presentation of 6.3 months and healthcare delay of 17.8 months. 54.8% of patients were diagnosed with asthma. Earlier presentation to otolaryngologist was associated with shorter healthcare delay and total time to diagnosis (rho = 0.75, rho = 0.99, P < .0001). Earlier CT imaging was correlated to shorter healthcare delay (rho = 0.84, P < .0001) and total time to diagnosis (rho = 0.74, P < .001), while earlier PFTs were correlated to shorter total time to diagnosis alone (rho = 0.71, P = .01). During evaluation, 10.5% (n = 17/124) of patients had ED visits and 13.7% (n = 13/124) patients were hospitalized. Before diagnosis, 7% (9/124) of patients underwent surgeries (including 3% (n = 4) undergoing tracheostomy) and 8% (n = 10) of patients required unplanned urgent endoscopic surgery that may have been avoided with earlier diagnosis.

CONCLUSION

iSGS diagnosis is frequently delayed, resulting in additional surgeries (including tracheostomy), ED visits, and hospitalizations. Further, patients' symptoms are commonly attributed to asthma. Earlier otolaryngologist evaluation, PFTs, and CT imaging may expedite iSGS diagnosis.

LEVEL OF EVIDENCE

4 Laryngoscope, 132:413-418, 2022.

Endoscopic Resection and Mucosal Reconstitution With Epidermal Grafting: A Pilot Study in Idiopathic Subglottic Stenosis

OBJECTIVE

To describe technical aspects and surgical outcomes of endoscopic resection and mucosal reconstitution with epidermal grafting (ie, the Maddern procedure) in the treatment of idiopathic subglottic stenosis.

STUDY DESIGN

Medical record abstraction.

SETTING

Johns Hopkins Hospital.

METHODS

Retrospective series of 9 adults with idiopathic subglottic stenosis who underwent the Maddern procedure by a single surgeon over a 5-year period. Prespecified outcomes included (1) perioperative outcomes (Clavien-Dindo grade 4/5 complications, need for staged tracheostomy, hospital length of stay), (2) postoperative outcomes (peak expiratory flow rate [PEFR], need for subsequent airway surgery, tracheostomy at follow-up), and (3) patient-reported quality-of-life outcomes (Clinical COPD Questionnaire, Voice Handicap Index-10, Eating Assessment Tool-10, and 12-Item Short Form Version 2). Wilcoxon matched-pairs signed rank test and Kaplan-Meier analysis were performed.

RESULTS

There were no Clavien-Dindo grade 4/5 complications; 2 patients required unplanned staged tracheostomy; and the median length of stay was 3 days. Following endoscopic resection and stent removal, a median of 2 laser resurfacing procedures were required. Two patients developed recurrent stenosis requiring cricotracheal resection (CTR). There were significant improvements in PEFR, Clinical COPD Questionnaire, and Voice Handicap Index-10, without significant difference in Eating Assessment Tool-10. The 12-Item Short Form Version 2 approximated the population norm. Kaplan-Meier analysis demonstrated significant improvement in time to surgery after the final laser resurfacing.

CONCLUSION

The Maddern procedure has a low complication rate and offers durable physiologic improvement in PEFR, limiting need for additional procedures. Risks included need for CTR salvage, temporary tracheostomy, phlegm accumulation, and laryngospasm. It is a surgical option for patients with short dilation intervals who prefer to avoid the risks of CTR.

GMP compliant isolation of mucosal epithelial cells and fibroblasts from biopsy samples for clinical tissue engineering

Engineered epithelial cell sheets for clinical replacement of non-functional upper aerodigestive tract mucosa are regulated as medicinal products and should be manufactured to the standards of good manufacturing practice (GMP). The current gold standard for growth of epithelial cells for research utilises growth arrested murine 3T3 J2 feeder layers, which are not available for use as a GMP compliant raw material. Using porcine mucosal tissue, we demonstrate a new method for obtaining and growing non-keratinised squamous epithelial cells and fibroblast cells from a single biopsy, replacing the 3T3 J2 with a growth arrested primary fibroblast feeder layer and using pooled Human Platelet lysate (HPL) as the media serum supplement to replace foetal bovine serum (FBS). The initial isolation of the cells was semi-automated using an Octodissociator and the resultant cell suspension cryopreservation for future use. When compared to the gold standard of 3T3 J2 and FBS containing medium there was no reduction in growth, viability, stem cell population or ability to differentiate to mature epithelial cells. Furthermore, this method was replicated with Human buccal tissue, providing cells of sufficient quality and number to create a tissue engineered sheet.

The Proximal Airway Is a Reservoir for Adaptive Immunologic Memory in Idiopathic Subglottic Stenosis

OBJECTIVES/HYPOTHESIS

Characterization of the localized adaptive immune response in the airway scar of patients with idiopathic subglottic stenosis (iSGS).

STUDY DESIGN

Basic Science.

METHODS

Utilizing 36 patients with subglottic stenosis (25 idiopathic subglottic stenosis [iSGS], 10 iatrogenic post-intubation stenosis [iLTS], and one granulomatosis with polyangiitis [GPA]) we applied immunohistochemical and immunologic techniques coupled with RNA sequencing.

RESULTS

iSGS, iLTS, and GPA demonstrate a significant immune infiltrate in the subglottic scar consisting of adaptive cell subsets (T cells along with dendritic cells). Interrogation of T cell subtypes showed significantly more CD69+ CD103+ CD8+ tissue resident memory T cells (TRM ) in the iSGS airway scar than iLTS specimens (iSGS vs. iLTS; 50% vs. 28%, P = .0065). Additionally, subglottic CD8+ clones possessed T-cell receptor (TCR) sequences with known antigen specificity for viral and intracellular pathogens.

CONCLUSIONS

The human subglottis is significantly enriched for CD8+ tissue resident memory T cells in iSGS, which possess TCR sequences proven to recognize viral and intracellular pathogens. These results inform our understanding of iSGS, provide a direction for future discovery, and demonstrate immunologic function in the human proximal airway. Laryngoscope, 131:610-617, 2021.

Can the Expiratory Disproportion Index Distinguish PVFMD from Subglottic Stenosis in Obese Patients?

OBJECTIVES

Expiratory disproportion index (EDI) is the ratio of forced expiratory volume in 1 second (FEV1) divided by peak expiratory flow rate (PEFR) multiplied by 100. Prominent EDI (>50) values can differentiate subglottic stenosis (SGS) from paradoxical vocal fold movement disorder (PVFMD), but this has not been verified when considering body habitus. We hypothesize that the predictive value of elevated EDI in differentiating SGS from PVFMD will be lower in obese patients than non-obese patients.

METHODS

Patients ≥ 18 years old with recorded PFT values, BMI, and airway imaging were reviewed retrospectively from 01/2011 to 10/2018. EDI was recorded for 4 cohorts: non-obese/SGS, non-obese/ PVFMD, obese/SGS, and obese/ PVFMD, to determine the mean EDI and the sensitivity/specificity of an elevated EDI.

RESULTS

Mean EDI values were 69.32 and 48.38 in the non-obese SGS and PVFMD groups, respectively (P < .01). They were 58.89 and 47.67 in the obese SGS and PVFMD groups, respectively (P < .05). At a threshold of >50, EDI had a sensitivity of 90.0% and specificity of 51.6% in differentiating between SGS and PVFMD cases in non-obese patients and 51.6% and 63.6% in obese patients.

CONCLUSION

Prior literature has established that EDI can distinguish SGS from PVFMD in the general population. Our results show that the mean EDI values were significantly different in both cohorts, but an elevated EDI was not as sensitive at identifying SGS cases in obese patients. This suggests that the EDI should be used with caution in obese patients and should not be relied upon to rule out SGS.

LEVEL OF EVIDENCE

3.

Effect of inhaled fluticasone propionate on laryngotracheal stenosis after balloon dilation: a randomized controlled trial

PURPOSE

Laryngotracheal stenosis describes various airflow compromising conditions leading to laryngeal and tracheal narrowing, including subglottic and tracheal stenosis. Direct laryngobronchoscopy is the diagnostic gold standard for laryngotracheal stenosis. This study aimed to explore the effect of inhaled fluticasone propionate as adjuvant medical therapy in patients with laryngotracheal stenosis after balloon dilation.

METHODS

This prospective randomized controlled trial was conducted from April 2019 to April 2020. Fourteen adults (≥ 18 years) with laryngotracheal stenosis consented to participate. All patients underwent endoscopic balloon dilation. Seven patients were treated with inhaled fluticasone propionate, and seven acted as controls. Detailed documentation of operative findings and pre- and post-balloon dilation spirometry measurements were recorded. Basic demographic data and operative details, including information about the percentage of laryngotracheal stenosis, distance of laryngotracheal stenosis from the vocal cords, the stenotic segment vertical length, and the largest endotracheal tube used before and after dilation were noted.

RESULTS

Spirometry measurements were obtained on 34 occasions (17 before and 17 after balloon dilation). The two groups were similar in spirometry values after treatment. Both groups had significantly improved on most spirometry values after balloon dilation.

CONCLUSION

We found that using inhaled steroids after balloon dilatation in patients with laryngotracheal stenosis had no benefit over non-user patients in spirometry parameters during the short postoperative follow-up. To confirm this outcome, we recommend a large-scale double-blind study with a longer follow-up period.

Voice and Swallowing Outcomes Following Airway Reconstruction in Adults: A Systematic Review

OBJECTIVES

Laryngotracheal stenosis is a rare condition characterized by upper airway narrowing. Reconstructive surgical treatment aims to manage the area of stenosis to improve dyspnea and can impact voice and swallowing function. This article critically evaluates the literature about voice and swallowing outcomes in adults with laryngotracheal stenosis who undergo reconstructive surgery.

STUDY DESIGN

Systematic review.

METHODS

Six databases were searched for articles referring to voice and swallowing outcome measures following reconstruction procedures in adults with laryngotracheal stenosis. Screening was completed using predefined inclusion/exclusion criteria.

RESULTS

A total of 143 abstracts were reviewed, with 67 articles selected for full-text review. Twenty studies met the inclusion criteria. Data extraction was completed with the Strengthening Reporting of Observational Studies in Epidemiology checklist with Oxford Centre for Evidence-Based Medicine Level of Evidence used to indicate quality. Risk of bias was assessed using the Risk of Bias Assessment Tool for Non-Randomized Studies. All studies scored a high risk of bias in at least one of the domains. Selection and timing of outcome measures was heterogenous, and there was limited information provided about rationale or reliability.

CONCLUSIONS

The literature acknowledges the importance of voice and swallowing outcomes following airway reconstruction. Studies show correlation between reconstructive surgery and deterioration in vocal function; there are no consistent data about swallowing outcomes. The lack of a core outcome measures set for adults with laryngotracheal stenosis limits the findings of this review. Further research is needed to establish clear criteria for robust and clinically relevant outcome measurement. Laryngoscope, 131:146-157, 2021.

Development of a Bioinspired, Self-Adhering, and Drug-Eluting Laryngotracheal Patch

OBJECTIVES/HYPOTHESIS

Novel laryngotracheal wound coverage devices are limited by complex anatomy, smooth surfaces, and dynamic pressure changes and airflow during breathing. We hypothesize that a bioinspired mucoadhesive patch mimicking how geckos climb smooth surfaces will permit sutureless wound coverage and also allow drug delivery.

STUDY DESIGN

ex-vivo.

METHODS

Polycaprolactone (PCL) fibers were electrospun onto a substrate and polyethylene glycol (PEG) - acrylate flocks in varying densities were deposited to create a composite patch. Sample topography was assessed with laser profilometry, material stiffness with biaxial mechanical testing, and mucoadhesive testing determined cohesive material failure on porcine tracheal tissue. Degradation rate was measured over 21 days in vitro along with dexamethasone drug release profiles. Material handleability was evaluated via suture retention and in cadaveric larynges.

RESULTS

Increased flocking density was inversely related to cohesive failure in mucoadhesive testing, with a flocking density of PCL-PEG-2XFLK increasing failure strength to 6880 ± 1810 Pa compared to 3028 ± 791 in PCL-PEG-4XFLK density and 1182 ± 262 in PCL-PEG-6XFLK density. The PCL-PEG-2XFLK specimens had a higher failure strength than PCL alone (1404 ± 545 Pa) or PCL-PEG (2732 ± 840). Flocking progressively reduced composite stiffness from 1347 ± 15 to 763 ± 21 N/m. Degradation increased from 12% at 7 days to 16% after 10 days and 20% after 21 days. Cumulative dexamethasone release at 0.4 mg/cm² concentration was maintained over 21 days. Optimized PCL-PEG-2XFLK density flocked patches were easy to maneuver endoscopically in laryngeal evaluation.

CONCLUSIONS

This novel, sutureless, patch is a mucoadhesive platform suitable to laryngeal and tracheal anatomy with drug delivery capability.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:1958-1966, 2021.

Proteomic and Genomic Methylation Signatures of Idiopathic Subglottic Stenosis

OBJECTIVE

Idiopathic subglottic stenosis (iSGS) is a chronic inflammatory condition that causes dyspnea and affects middle-aged women of White race and non-Latino or Hispanic ethnicity. To better characterize its phenotype and pathogenesis, we assessed the proteomic and genomic methylation signatures of subglottic tissue collected from iSGS patients compared to controls.

STUDY DESIGN

Molecular analysis of clinical biospecimens.

METHODS

We collected subglottic tissue biopsies from 12 patients during direct laryngoscopy, immediately prior to surgical treatment of iSGS; as well as from 4 age-, sex-, and race/ethnicity-matched control patients undergoing other direct laryngoscopic procedures. We isolated protein and genomic DNA, acquired proteomic data using label-free quantitative mass spectrometry techniques, and acquired genome-wide methylation data using bisulfite conversion and a microarray platform. We compared molecular profiles across the iSGS and control groups, and with respect to clinical course in the iSGS group. Eight of the 12 iSGS patients underwent subsequent blood collection and plasma isolation for further assessment.

RESULTS

Proteomic analysis revealed 42 differentially abundant proteins in the iSGS biopsies compared to controls, inferring enrichment of biological pathways associated with early wound healing, innate immunity, matrix remodeling, and metabolism. Proteome-based hierarchical clustering organized patients into two iSGS and one control subgroups. Methylation analysis revealed five hypermethylated genes in the iSGS biopsies compared to controls, including the biotin recycling enzyme biotinidase (BTD). Follow-up analysis showed elevated plasma BTD activity in iSGS patients compared to both controls and published normative data.

CONCLUSION

iSGS exhibits distinct proteomic and genomic methylation signatures. These signatures expand current understanding of the iSGS phenotype, support the possibility of disease subgroups, and should inform the direction of future experimental studies.

LEVEL OF EVIDENCE

Not applicable Laryngoscope, 131:E540-E546, 2021.

Familial Aggregation in Idiopathic Subglottic Stenosis

OBJECTIVE

To evaluate inheritance patterns and define the familial clustering rate of idiopathic subglottic stenosis (iSGS).

STUDY DESIGN

Retrospective observational study.

SETTING

International multicenter collaborative of >30 tertiary care centers.

METHODS

Patients with a clinically confirmed iSGS diagnosis within the North American Airway Collaborative's iSGS¹⁰⁰⁰ cohort consented between 2014 and 2018 were eligible for enrollment. Patient demographics and disease severity were abstracted from the collaborative's iSGS longitudinal registry. Pedigrees of affected families were created.

RESULTS

A total of 810 patients with iSGS were identified. Positive family history for iSGS was reported in 44 patients in 20 families. The rate of familial clustering in iSGS is 2.5%. Mean age of disease onset is 42.6 years. Of the 44 patients with familial aggregation of iSGS, 42 were female and 2 were male; 13 were mother-daughter pairs and 2 were father-daughter pairs. There were 3 sister-sister pairs. There was 1 niece-aunt pair and 2 groups of 3 family members. One pedigree demonstrated 2 affected mother-daughter pairs, with the mothers being first-degree paternal cousins. Inheritance is non-Mendelian, and anticipation is present in 11 of 13 (84%) parent-offspring pairs. The mean age of onset between parents (48.4 years) and offspring (36.1 years) was significantly different (P = .016).

CONCLUSION

This study quantifies the rate of familial clustering of iSGS at 2.5%. Inheritance is non-Mendelian, and disease demonstrates anticipation. These data suggest that there may be a genetic contribution in iSGS.

Idiopathic subglottic stenosis: a review

Idiopathic subglottic stenosis (iSGS) is a fibrotic disease of unclear etiology that produces obstruction of the central airway in the anatomic region under the glottis. The diagnosis of this entity is difficult, usually delayed and confounded with other common respiratory diseases. No apparent etiology is identified even after a comprehensive workup that includes a complete history, physical examination, pulmonary function testing, auto-antibodies, imaging studies, and endoscopic procedures. This approach, however, helps to exclude other conditions such as granulomatosis with polyangiitis (GPA). It is also helpful to characterize the lesion and outline management strategies. Therapeutic endoscopic procedures and surgery are the most common management modalities, but medical therapy can also play a significant role in preventing or delaying recurrence. In this review, we describe the morphology, pathophysiology, clinical presentation, evaluation, management, and prognosis of iSGS.

Endoscopic Treatment of Idiopathic Subglottic Stenosis: A Systematic Review

Purpose: To identify different endoscopic techniques for treatment of idiopathic subglottic stenosis (iSGS) and evaluate treatment results.

Methods: Embase and Cochrane Library were searched for publications on endoscopically treated iSGS. Identified interventions included procedures with cold knife, dilation (rigid or balloon), or laser (CO₂ or Nd:YAG), used in several combinations and supplemented with mitomycin C and/or corticosteroids. Primary endpoint was time interval between successive endoscopic procedures. Secondary endpoints were stenosis recurrence rate, total number of interventions per patient during follow-up, tracheotomy rate, and rate of open surgery.

Results: Eighty-six abstracts were reviewed and 15 series were included in the analysis. Mean sample size was 57 subjects (range 10–384, σ 90.84) and mean age was 47 years (range 36–54, σ 4.45). Time interval ranged from 2 to 21 months [weighted mean (WM): 12]. Rate of stenosis recurrence ranged from 40 to 100% (WM: 68%). Mean amount of interventions per patient varied between 1.8 and 8.3 (WM: 3.7). Tracheotomy rate varied between 0 and 26% (WM: 7%) and rate of open surgery varied between 0 and 27% (WM: 10%). Single modality CO₂ lasering showed highest rate of recurrence, highest amount of interventions, and shortest time interval. Combined techniques generated overall better outcomes.

Conclusions: A multitude of endoscopic techniques are being used for treating iSGS, all with a considerable recurrence rate. In this review, no superior modality could be identified. Consequently, endoscopic management could be considered a valuable primary treatment option for iSGS, but open surgery still plays an important role.

Vocal fold fixation due to proximal stenosis progression complicating idiopathic subglottic stenosis

Purpose

This study examined the incidence and risk factors for vocal fold fixation due to proximal progression of idiopathic subglottic stenosis (ISS) over the course of serial treatments.

Methods

Records of 22 consecutive patients with ISS treated between 2004 and 2016 were retrospectively reviewed. Patient, stenosis, and treatment details were recorded. Cox regression was used to identify independent predictors of vocal fold fixation.

Results

All patients were female and mean age at diagnosis was 46 ± 7 years. In five patients, the stenosis was within 15 mm of the glottis at first treatment. Vocal fold fixation due to proximal stenosis progression occurred in seven (32%) patients. It led to permanent hoarseness due to unilateral vocal fold fixation in two patients and caused airway compromise due to bilateral vocal fixation in two other patients. No airway-related deaths occurred and no patient required a tracheostomy. Stenosis incision using coblation or potassium titanyl phosphate laser, and an initial glottis-to-stenosis (GtS) distance < 15 mm significantly increased the risk of proximal stenosis progression on univariable analysis.

Conclusion

Vocal fold fixation due to proximal stenosis progression is a significant complication of idiopathic subglottic stenosis and causes permanent voice and/or airway sequelae. It should be actively looked for and documented every time a patient is assessed. If a reduction in the GtS distance is observed, definitive surgery should be promptly considered before proximal stenosis progression compromises the efficacy and safety of definitive treatment or, worse, causes vocal fold fixation.

Predictors of recurrence after surgical treatment of idiopathic progressive subglottic stenosis

Idiopathic progressive subglottic stenosis is a rare cause of tracheal narrowing. Partial cricotracheal resection and anastomosis can cure idiopathic stenosis, even if some patients may require multiple interventions and experience voice and swallowing deterioration. We investigated risk factors for retreatment and assessed the impact of crico-tracheal resection on functional parameters. We conducted a retrospective multicentric study on 44 female patients (mean age 52.6 ± 13.1 years) affected by idiopathic stenosis and treated by crico-tracheal resection between 2002 and 2016. Functional outcomes after crico-tracheal resection were assessed by the airway-dyspnoea-voice-swallowing score (range 1-5, with “1” expressing normal and “5” completely altered function). Previous treatments, grade of stenosis, site, airway comorbidities, age and resection length were tested as predictors of postoperative complications and number of additional treatments, using bivariate and multivariate analysis. The overall decannulation rate was 97.3%. The dyspnoea score improved (mean variation 1.4 ± 1.0; p < 0.001), while voice and swallowing were negatively affected (mean variation 1.6 ± 0.9 and 0.5 ± 0.7, respectively; p < 0.001). Airway comorbidities were associated with a higher rate of complications (p < 0.05). Retreatments were more frequent in patients with postoperative complications (p < 0.05). The length of resection correlated with the number of subsequent treatments (R = 0.52; p < 0.01). At multivariate analysis, post-operative complications were predicted by comorbidities and disease stage (p < 0.05); number of retreatments was linked to the length of resection (p < 0.05) as well as with the application of mitomycin C (p < 0.001). Crico-tracheal resection for idiopathic progressive subglottic stenosis offers good functional results in terms of airway patency. These data suggest that a higher complication rate can be expected in patients affected by comorbidities. Moreover, more extensive surgical resection seems to be associated with the occurrence and number of subsequent retreatments. On the contrary, the local application of an anti-proliferative drug does not seem to be of use in preventing recurrences.

The role of pepsin in epithelia-mesenchymal transition in idiopathic subglottic stenosis

OBJECTIVES

Idiopathic subglottic stenosis (iSGS) is commonly characterized by laryngeal fibrosis thought to arise by epithelia-mesenchymal transition (EMT) induced by chronic inflammation. Pepsin is a potent inducer of inflammation in the airways during chronic laryngopharyngeal reflux and has been observed in the subglottic mucosa of patients with iSGS, absent in normal mucosa. The aim of this study was to examine the effect of pepsin on mechanisms of EMT in laryngeal cells with implications for iSGS.

STUDY DESIGN

In vitro translational research study.

METHODS

Human laryngeal epithelial cell cultures were exposed to 0.1 mg/mL or 1.0 mg/mL pepsin at pH7 for 24 and 48 hours, or media pH5 ± 0.1 mg/mL pepsin for 10 minutes and harvested after 24 and 48 hours. EMT marker expression was measured by qPCR and enzyme-linked immunosorbent assays. Wound-healing scratch assay was performed on immortalized human vocal fold fibroblasts pretreated with media pH5 ± 0.1 mg/mL pepsin (10 minutes) or continuously treated with media pH7 ± 0.1 to 1 mg/mL pepsin for 24 hours.

RESULTS

Pepsin yielded no effect on MMP1, MMP9, FN1, COL1A1, HAS2, or CDH1 gene expression or matrix metalloproteinase-9 or fibronectin protein expression, either alone or in the presence of weak acid. Pepsin and/or acid produced no effect on fibroblast migration.

CONCLUSION

Whereas pepsin has been shown to be present in the subglottic mucosa of patients with iSGS, this in vitro acute exposure investigation does not provide evidence of a direct causal role for development of fibrosis in subglottic epithelial cell cultures.

LEVELS OF EVIDENCE

NA. Laryngoscope, 130:154-158, 2020.

Health Care Costs and Cost-effectiveness in Laryngotracheal Stenosis

OBJECTIVE

Laryngotracheal stenosis (LTS) is resource-intensive disease. The cost-effectiveness of LTS treatments has not been adequately explored. We aimed to conduct a cost-effectiveness analysis comparing open reconstruction (cricotracheal/tracheal resection [CTR/TR]) with endoscopic dilation in the treatment of LTS.

STUDY DESIGN

Retrospective cohort.

SETTING

Tertiary referral center (2013-2017).

SUBJECTS AND METHODS

Thirty-four LTS patients were recruited. Annual costs were derived from the Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University. Cost-effectiveness analysis compared CTR/TR versus endoscopic dilation at a willingness-to-pay threshold of $50,000 per quality-adjusted life year (QALY) over 5- and 10-year time horizons. The incremental cost-effectiveness ratio (ICER) was calculated with deterministic analysis and tested for sensitivity with univariate and probabilistic sensitivity analysis.

RESULTS

Mean LTS costs were $4080.09 (SE, $569.29) annually for related health care visits. The major risk factor for increased cost was etiology of stenosis. As compared with idiopathic patients, patients with intubation-related stenosis had significantly higher annual costs ($5286.56 vs $2873.62, P = .03). The cost of CTR/TR was $8583.91 (SE, $2263.22). Over a 5-year time horizon, CTR/TR gained $896 per QALY over serial dilations and was cost-effective. Over a 10-year time horizon, CTR/TR dominated dilations with a lower cost and higher QALY.

CONCLUSION

The cost of treatment for LTS is significant. Patients with intubation-related stenosis have significantly higher annual costs than do idiopathic patients. CTR/TR contributes significantly to cost in LTS but is cost-effective versus endoscopic dilations for appropriately selected patients over a 5- and 10-year horizon.

T-Helper 2 Lymphocyte Immunophenotype Is Associated With Iatrogenic Laryngotracheal Stenosis

OBJECTIVE/HYPOTHESIS

This prospective controlled human and murine study assessed the presence of inflammatory cells and cytokines to test the hypothesis that immune cells are associated with fibroproliferation in iatrogenic laryngotracheal stenosis (iLTS).

METHODS

Inflammation was assessed by histology and immunofluorescence (IF), quantitative real-time polymerase chain reaction (qRT-PCR), and flow cytometry of cricotracheal resections of iLTS patients compared to normal controls. An iLTS murine model assessed the temporal relationship between inflammation and fibrosis.

RESULTS

iLTS specimens showed increased inflammation versus normal controls (159/high power field [hpf] vs. 119/hpf, P = 0.038), and increased CD3 + T-cells, CD4 + cells, and CD3+/CD4 + T-helper (T_H ) cells (all P < 0.05). The inflammatory infiltrate was located immediately adjacent to the epithelial surface in the superficial aspect of the thickened lamina propria. Human flow cytometry and qRT-PCR showed a significant increase in interleukin (IL)-4 gene expression, indicating a T_H 2 phenotype. Murine IF revealed a dense CD4 + T-cell inflammatory infiltrate on day 4 to 7 postinjury, which preceded the development of fibrosis. Murine flow cytometry and qRT-PCR studies mirrored the human ones, with increased T-helper cells and IL-4 in iLTS versus normal controls.

CONCLUSION

CD3/CD4 + T-helper lymphocytes and the proinflammatory cytokine IL-4 are associated with iLTS. The association of a T_H 2 immunophenotype with iLTS is consistent with findings in other fibroinflammatory disorders. The murine results reveal that the inflammatory infiltrate precedes the development of fibrosis. However, human iLTS specimens with well-developed fibrosis also contain a marked chronic inflammatory infiltrate, suggesting that the continued release of IL-4 by T-helper lymphocytes may continue to propagate iLTS.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:177-186, 2019.

Pathologic Fibroblasts in Idiopathic Subglottic Stenosis Amplify Local Inflammatory Signals

OBJECTIVE

To characterize the phenotype and function of fibroblasts derived from airway scar in idiopathic subglottic stenosis (iSGS) and to explore scar fibroblast response to interleukin 17A (IL-17A).

STUDY DESIGN

Basic science.

SETTING

Laboratory.

SUBJECTS AND METHODS

Primary fibroblast cell lines from iSGS subjects, idiopathic pulmonary fibrosis subjects, and normal control airways were utilized for analysis. Protein, molecular, and flow cytometric techniques were applied in vitro to assess the phenotype and functional response of disease fibroblasts to IL-17A.

RESULTS

Mechanistically, IL-17A drives iSGS scar fibroblast proliferation ( P < .01), synergizes with transforming growth factor ß1 to promote extracellular matrix production (collagen and fibronectin; P = .04), and directly stimulates scar fibroblasts to produce chemokines (chemokine ligand 2) and cytokines (IL-6 and granulocyte-macrophage colony-stimulating factor) critical to the recruitment and differentiation of myeloid cells ( P < .01). Glucocorticoids abrogated IL-17A-dependent iSGS scar fibroblast production of granulocyte-macrophage colony-stimulating factor ( P = .02).

CONCLUSION

IL-17A directly drives iSGS scar fibroblast proliferation, synergizes with transforming growth factor ß1 to promote extracellular matrix production, and amplifies local inflammatory signaling. Glucocorticoids appear to partially abrogate fibroblast-dependent inflammatory signaling. These results offer mechanistic support for future translational study of clinical reagents for manipulation of the IL-17A pathway in iSGS patients.

Treatment options in idiopathic subglottic stenosis: protocol for a prospective international multicentre pragmatic trial

INTRODUCTION

Idiopathic subglottic stenosis (iSGS) is an unexplained progressive obstruction of the upper airway that occurs almost exclusively in adult, Caucasian women. The disease is characterised by mucosal inflammation and localised fibrosis resulting in life-threatening blockage of the upper airway. Because of high recurrence rates, patients with iSGS will frequently require multiple procedures following their initial diagnosis. Both the disease and its therapies profoundly affect patients' ability to breathe, communicate and swallow. A variety of treatments have been advanced to manage this condition. However, comparative data on effectiveness and side effects of the unique approaches have never been systematically evaluated. This study will create an international, multi-institutional prospective cohort of patients with iSGS. It will compare three surgical approaches to determine how well the most commonly used treatments in iSGS 'work' and what quality of life (QOL) trade-offs are associated with each approach.

METHODS AND ANALYSIS

A prospective pragmatic trial comparing the 'Standard of Care' for iSGS at multiple international institutions. Patients with a diagnosis of iSGS without clinical or laboratory evidence of vasculitis or a history of endotracheal intubation 2 years prior to symptom onset will be included in the study. Prospective evaluation of disease recurrence requiring operative intervention, validated patient-reported outcome (PRO) measures as well as patient-generated health data (mobile peak flow recordings and daily steps taken) will be longitudinally tracked for 36 months. The primary endpoint is treatment effectiveness defined as time to recurrent operative procedure. Secondary endpoints relate to treatment side effects and include PRO measures in voice, swallowing, breathing and global QOL as well as patient-generated health data.

ETHICS AND DISSEMINATION

This protocol was approved by the local IRB Committee of the Vanderbilt University Medical Center in July 2015. The findings of the trial will be disseminated through peer-reviewed journals, national and international conference presentations and directly to patient with iSGS via social media-based support groups.

TRIAL REGISTRATION NUMBER

NCT02481817.

Quality-of-Life Metrics Correlate With Disease Severity in Idiopathic Subglottic Stenosis

OBJECTIVES

Idiopathic subglottic stenosis (ISGS) can have significant impacts on quality of life (QOL), but it remains unclear how patients' subjective responses correlate with objective measurement of disease severity. Peak expiratory flow percentage (PEF%) has been shown to be an effective measure of disease severity in subglottic stenosis. This study aims to identify the key QOL questions correlated with PEF% and proposes a statistical model for prediction of disease severity.

METHODS

Patients with ISGS presenting to an academic laryngologist were included retrospectively from 2012 to 2016. Peak expiratory flow percentage (age, sex, and height adjusted) was recorded for each visit, along with four validated QOL instruments (European QOL-Five Dimensions; RAND 36-Item Health Survey; Clinical COPD [Chronic Obstructive Pulmonary Disease] Questionnaire; and the Airway, Dyspnea, Voice, and Swallowing Summary Assessment). A stepwise multiple linear regression was used to identify statistically significant independent variables correlated with PEF%, and a model was built with these variables.

RESULTS

Thirty-two patients were included, with a total of 271 patient encounters. Overall scores from each of the four QOL instruments were correlated with PEF% values recorded each visit (P < 0.05). Question responses correlating most positively included overall breathlessness, difficulty catching breath, cough within the past week, dyspnea with moderate activity, perception that voice changes are restricting social life, and overall general health (all P < 0.01). A model constructed using six nonoverlapping questions yielded an adjusted R2 of 0.58.

CONCLUSION

Quality of life is correlated to PEF% in ISGS. Using a limited number of QOL questions, clinicians can predict objective worsening or improvement of disease severity, as measured by spirometry.

LEVEL OF EVIDENCE

2b. Laryngoscope, 2017.

Endoscopic management of tissue-engineered tracheal graft stenosis in an ovine model

OBJECTIVE

To evaluate the safety and efficacy of bronchoscopic interventions in the management of tissue-engineered tracheal graft (TETG) stenosis.

STUDY DESIGN

Animal research study.

METHODS

TETGs were constructed with seeded autologous bone marrow-derived mononuclear cells on a bioartificial graft. Eight sheep underwent tracheal resection and orthotopic implantation of this construct. Animals were monitored by bronchoscopy and fluoroscopy at 3 weeks, 6 weeks, 3 months, and 4 months. Bronchoscopic interventions, including dilation and stenting, were performed to manage graft stenosis. Postdilation measurements were obtained endoscopically and fluoroscopically.

RESULTS

Seven dilations were performed in six animals. At the point of maximal stenosis, the lumen measured 44.6 ± 8.4 mm² predilation and 50.7 ± 14.1 postdilation by bronchoscopy (P = 0.3517). By fluoroscopic imaging, the airway was 55.9 ± 12.9 mm² predilation and 65.9 ± 22.4 mm² postdilation (P = 0.1303). Stents were placed 17 times in six animals. Pre- and poststenting lumen sizes were 62.8 ± 38.8 mm² and 80.1 ± 54.5 mm² by bronchoscopy (P = 0.6169) and 77.1 ± 38.9 mm² and 104 ± 60.7 mm² by fluoroscopy (P = 0.0825). Mortality after intervention was 67% with dilation and 0% with stenting (P = 0.0004). The average days between bronchoscopy were 8 ± 2 for the dilation group and 26 ± 17 in the stenting group (P = 0.05). One hundred percent of dilations and 29% of stent placements required urgent follow-up bronchoscopy (P = 0.05).

CONCLUSION

Dilation has limited efficacy for managing TETG stenosis, whereas stenting has a more lasting clinical effect.

LEVEL OF EVIDENCE

NA. Laryngoscope, 127:2219-2224, 2017.

Idiopathic subglottic stenosis: an epidemiological single-center study

A retrospective epidemiological study of patients treated for idiopathic subglottic stenosis (ISS) during 2003-2013 at Oslo University Hospital, Rikshospitalet, was undertaken to assess its incidence, management and treatment outcomes. Out of a total of 123 patients with subglottic stenosis (84 female, 39 men), 38 patients were diagnosed with ISS, all of whom were female. Of these, 23 lived in the South-Eastern Norway Regional Health Authority, representing an incidence of 0.2 per 100,000 (95% CI 0.13-0.3) in this region of 2.9 million inhabitants. Mean age at diagnosis was 54 years (range 20-85 years), and the mean interval between symptom onset and diagnosis was 3.1 years. The 38 patients with ISS underwent a total of 132 operations between 2003 and 2013. All patients were managed endoscopically using laser surgery, with or without corticosteroids and Mitomycin C, with dilatation by balloon or bougie. Eight patients (21.1%) required only one procedure, while 30 patients (78.9%) had multiple operations. The median follow-up for all patients from the first operation was 5.3 years. The mean interval between procedures was 1 year for patients aged 20-48 years, 1.3 years for patients aged 49-61 years and 3.0 years for patients aged 62-85 years. No clinically significant complications were observed. In conclusion, the symptoms of ISS can be treated effectively with laser surgery and dilatation but the recurrence rate remains high and the time interval between operations does not increase with time, making ISS a continuing challenge.

Idiopathic subglottic stenosis is associated with activation of the inflammatory IL-17A/IL-23 axis

OBJECTIVES/HYPOTHESIS

Idiopathic subglottic stenosis (iSGS) is a rare and devastating extrathoracic obstruction involving the lower laryngeal and upper tracheal airway. It arises without known antecedent injury or associated disease process. Persistent mucosal inflammation and a localized fibrotic response are hallmarks of the disease. Despite the initial clinical description of iSGS more than 40 year ago, there have been no substantive investigations into the pathogenesis of this enigmatic and progressive airway obstruction. In these studies, we present the initial characterization of the molecular pathogenesis underlying the fibrosing phenotype of iSGS.

METHODS

Utilizing 20 human iSGS and healthy control specimens, we applied histologic, immunohistochemical, molecular, and immunologic techniques.

RESULTS

We demonstrate significant activation of the canonical IL-23/IL-17A pathway in the tracheal mucosa of iSGS patients, as well as identify γδ T cells as the primary cellular source of IL-17A.

CONCLUSION

Our results suggest that aberrant mucosal immune activation is a component in of the pathogenesis of iSGS. Most critically, our work offers new targets for future therapeutic intervention.

LEVEL OF EVIDENCE

NA Laryngoscope, 126:E356-E361, 2016.

Molecular analysis of idiopathic subglottic stenosis for Mycobacterium species

Objectives/Hypothesis

Idiopathic subglottic stenosis (iSGS) is an unexplained obstruction involving the lower laryngeal and upper tracheal airway. Persistent mucosal inflammation is a hallmark of the disease. Epithelial microbiota dysbiosis is found in other chronic inflammatory mucosal diseases; however, the relationship between tracheal microbiota composition and iSGS is unknown.

Given the critical role for host defense at mucosal barriers, we analyzed tissue specimens from iSGS patients for the presence of microbial pathogens.

Methods

Utilizing 30 human iSGS, 20 intubation‐related tracheal stenosis (iLTS), and 20 healthy control specimens, we applied molecular, immunohistochemical, electron microscopic, immunologic, and Sanger‐sequencing techniques.

Results

With unbiased culture‐independent nucleic acid, protein, and immunologic approaches, we demonstrate that Mycobacterium species are uniquely associated with iSGS. Phylogenetic analysis of the mycobacterial virulence factor rpoB suggests that, rather than Mycobacterium tuberculosis, a variant member of the Mycobacterium tuberculosis complex or a closely related novel mycobacterium is present in iSGS specimens.

Conclusion

These studies identify a novel pathogenic role for established large airway bacteria and provide new targets for future therapeutic intervention.

Level of Evidence

NA Laryngoscope, 127:179–185, 2017

Disease homogeneity and treatment heterogeneity in idiopathic subglottic stenosis

OBJECTIVES/HYPOTHESIS

Idiopathic subglottic stenosis (iSGS) is a rare and potentially life-threatening disease marked by recurrent and progressive airway obstruction frequently requiring repeated surgery to stabilize the airway. Unknown etiology and low disease prevalence have limited the ability to characterize the natural history of iSGS and resulted in variability in surgical management. It is uncertain how this variation relates to clinical outcomes.

STUDY DESIGN

Medical record abstraction.

METHODS

Utilizing an international, multi-institutional collaborative, we collected retrospective data on patient characteristics, treatment, and clinical outcomes. We investigated variation between and within open and endoscopic treatment approaches and assessed therapeutic outcomes; specifically, disease recurrence and need for tracheostomy at last follow-up.

RESULTS

Strikingly, 479 iSGS patients across 10 participating centers were nearly exclusively female (98%, 95% confidence interval [CI], 96.1-99.6), Caucasian (95%, 95% CI, 92.2-98.8), and otherwise healthy (mean age-adjusted Charlson Comorbidity Index 1.5; 95% CI, 1.44-1.69). The patients presented at a mean age of 50 years (95% CI, 48.8-51.1). A total of 80.2% were managed endoscopically, whereas 19.8% underwent open reconstruction. Endoscopic surgery had a significantly higher rate of disease recurrence than the open approach (chi(2) = 4.09, P = 0.043). Tracheostomy was avoided in 97% of patients irrespective of surgical approach (95% CI, 94.5-99.8). Interestingly, there were outliers in rates of disease recurrence between centers using similar treatment approaches.

CONCLUSION

Idiopathic subglottic stenosis patients are surprisingly homogeneous. The heterogeneity of treatment approaches and the observed outliers in disease recurrence rates between centers raises the potential for improved clinical outcomes through a detailed understanding of the processes of care.

LEVEL OF EVIDENCE

4. Laryngoscope, 126:1390-1396, 2016.