Surgical management of iSGS in pregnant patients: Survey among North American expertise centers.

OBJECTIVE: To identify, group and document the surgical management of idiopathic subglottic stenosis (iSGS) in pregnant women among North American centers with expertise in the treatment of airway stenosis. BACKGROUND: Idiopathic subglottic stenosis is a rare airway disease that primarily affects women in their third to fifth decade of life. Symptoms of iSGS often worsen during pregnancy and can present as a threat to optimal maternal and fetal health; however there is a lack of evidence addressing the management of iSGS in pregnancy. STUDY DESIGN: Cross-Sectional Survey Study. METHODS: A twenty-four question survey was designed to query the surgical management, ventilation, and perioperative considerations for pregnant patients with iSGS. Twenty-nine North American academic tertiary care centers with airway surgery expertise were identified. A designated surrogate for each center was contacted by email to distribute and obtain results of the survey. RESULTS: 17 centers responded. Most centers include differences in perioperative assessment such as frequency of consultation with a maternal/fetal medicine specialist. There is occasional use of a tocometer and rarely a non-stress test. Ventilation with intermittent jet ventilation or high-flow nasal cannula is favored. The surgical protocols include positional modifications, with pregnant patients in the left lateral decubitus position. The preferred timing for intervention is in the second or third trimester. CONCLUSION: This is the first national survey describing surgical and perioperative considerations for the pregnant patient with iSGS among centers with airway expertise in the United States and Canada.

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.

Hormone pathway comparison in non-idiopathic and idiopathic progressive subglottic stenosis.

PURPOSE: Our previous study on the idiopathic progressive subglottic stenosis (IPSS) highlighted a possible hormonal mechanism, with over-expression of estrogen receptors alpha (ER-α) and progesterone receptors (PR). We tested whether such over-expression take place in non-idiopathic subglottic stenosis (NISS) as well. METHODS: 37 specimens of iatrogenic NISS were analyzed (20 females; mean age, 59 ± 12 years; range 41-85). Immunoreactivity of ER-α and PR was calculated as the product of intensity (1 = weak, 2 = moderate, 3 = strong) and positive cells percentage (1 to 4, for < 10%, 10-50%, 50-80%, and > 80%). This score was calculated on the stenotic tissue (ST), and stenosis margins (SM). RESULTS: The expression of PR was significantly higher in ST of IPSS compared with female and male NISS patients (8.7 ± 3.1 vs. 4.9 ± 3.2, p < 0.001 for IPSS vs. female and 8.7 ± 3.1 vs. 2.1 ± 2.7, p < 0.01 for IPSS vs. male NISS patients). Contrarily, ER-α showed gender differences, as both IPSS and female NISS patients had similar, yet higher ER-α expression compared with male NISS patients (7.0 ± 4.2 vs. 6.5 ± 2.5, p = NS for IPSS vs. female and 7.0 ± 4.2 vs. 3.4 ± 2.0, p < 0.02 for IPSS vs. male NISS patients). There was no difference in fibroblast receptor expression between ST and SM. However, ER-α and PR expression was significantly lower in marginal mucous glands when compared with ST. CONCLUSIONS: The IPSS pathogenesis appears to be driven by hormonal mechanisms, in particular, by over-expression of PR. Marginal cells display a reduced hormone receptor density. This finding could be interpreted as a compensatory mechanism. These findings could open up for targeted IPSS treatment.

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.

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.

Using pulmonary function data to assess outcomes in the endoscopic management of subglottic stenosis.

OBJECTIVE: This study aimed to examine the authors' experience with endoscopic management of idiopathic subglottic stenosis (iSGS), and to identify pulmonary function test (PFT) values that can be used to quantify outcomes. METHODS: Retrospective review. RESULTS: Twenty-five patients with a new diagnosis of iSGS were seen between 2006 and 2012. Median age at surgery was 45.3 years (interquartile range [IQR], 38.5-67.0), and median body mass index was 28.7 kg/m(2) (IQR, 23.5-32.1). Forty-five procedures were performed. Median preoperative stenosis was 56.8% (Cotton-Myer grade 2). The typical stenosis began 15 mm below the true vocal folds and was 12 mm long. Median follow-up was 21.4 months (IQR, 5.1-43.1). For patients receiving multiple dilations, median time between procedures was 23.7 months. Four PFT parameters demonstrated significant improvement after intervention: (1) PEF (absolute change = 2.54 L/s), (2) PIF (absolute change = 1.57 L/s), (3) FEV1/PEF (absolute change = 0.44), and (4) FIF50% (absolute change = 1.71 L/s). PIF was the only parameter affected by using a larger balloon (P = .047). CONCLUSION: PEF, PIF, FEV1/PEF, and FIF50% improved significantly after endoscopic incision and dilation of iSGS, and this could potentially be used as a metric by which to evaluate outcomes in the endoscopic management of subglottic stenosis.

Idiopathic Subglottic and Tracheal Stenosis: A Survey of the Patient Experience.

OBJECTIVES: To report and compare patients' experiences with acquired subglottic stenosis (AS) versus idiopathic subglottic and tracheal stenosis (ISTS). METHODS: A survey was made available to patients with AS and ISTS. Results were analyzed for inter- and intragroup differences using a 2-tailed t test. RESULTS: The study included 160 survey participants (AS n = 28; ISTS n = 132), with a predominance of female participants (82% AS, 98% ISTS). Acid reflux was the most prevalent comorbidity across groups (42%-43%). A significant difference in time to diagnosis was found between groups, with 32% of AS patients diagnosed within 3 months of symptom onset, compared to 2% with ISTS. A diagnosis delay greater than 18 months occurred for 58% of ISTS patients. There was no difference in treatment approach, with the most common treatment being balloon dilation, followed by laser dilation. Tracheal resection was performed in 36% of patients in both groups. Patient satisfaction with surgical outcomes was significantly higher after tracheal resection (76%) compared to other treatment modalities (39%). CONCLUSIONS: ISTS remains a diagnostic challenge as highlighted by the delay in diagnosis compared to AS. There appears to be no historical or symptomatic factors specific to ISTS. Additionally, patients report increased satisfaction and symptom resolution after tracheal resection.

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.

Decision-Making in the Treatment of Idiopathic Subglottic Stenosis: A Survey of Laryngologists.

OBJECTIVE: Idiopathic subglottic stenosis (iSGS) is a rare condition involving the subglottic larynx and upper trachea, commonly affecting Caucasian females between 30 and 50 years of age. Despite its homogeneous presentation, clinical management for iSGS is yet to be standardized, leading to variability in outcomes between predominant interventions. In recognition of the heterogenicity in iSGS treatment and the need to improve patient outcomes, this study aimed to survey laryngologists to understand the factors influencing clinical decision-making and the incorporation of new treatment modalities for iSGS. METHODS: An online survey was sent to 145 academic laryngologists. The survey assessed respondents' professional backgrounds, experience treating iSGS, treatment algorithms, and how various patient factors affect management. RESULTS: Of the 87 (60%) laryngologists who responded to the survey, the most common clinical assessments were tracheoscopy/bronchoscopy (96.8%) and pulmonary function tests (43.6%). Endoscopic dilation (ED) was the most common primary treatment offered (97.5%): 28.7% of surveyed laryngologists offer SISI as a primary treatment, and 74.7% perform SISI as a planned postoperative treatment. The most common SISI protocol was repeated injections every 4-6 weeks for a series of 1-3 total injections. Notably, 9.2% perform the Maddern procedure. Routine algorithms of care involving surgery were most often based on prior experience and prior patient outcomes (75.9%) and conversations with colleagues (64.4%). Only 31% report using the same protocol learned during their fellowship training. CONCLUSION: This survey highlights significant variation in the management of patients with iSGS. Understanding the factors that influence decision-making may lead to potential standardization in heterogeneous treatment approaches and may improve clinical outcomes. LEVEL OF EVIDENCE: 5 Laryngoscope, 134:865-872, 2024.

Association between Estrogen Exposure and Idiopathic Subglottic Stenosis.

OBJECTIVE: Idiopathic subglottic stenosis (iSGS) is a rare, recurrent, fibroinflammatory disease affecting the larynx and proximal trachea. Given it occurs primarily in adult females, estrogen is speculated to play a central pathophysiological role. This study aimed to evaluate relationships between estrogen exposure, disease progression, and recurrence. METHODS: North American Airway Collaborative (NoAAC) data of adults with iSGS obstructive airway lesions, who underwent index endoscopic airway dilation, were used to identify associations between estrogen exposure, disease characteristics, and time to recurrence (TTR), and interventions were analyzed using Kruskal-Wallis test and Pearson coefficient. Cox proportional hazards regression models compared hazard ratios by estrogen exposure. Kaplan-Meier curves were plotted for TTR based on menopausal status. RESULTS: In all, 533 females had complete estrogen data (33% premenopausal, 17% perimenopausal, 50% postmenopausal). Median estrogen exposure was 28 years. Overall, there was no dose-response relationship between estrogen exposure and disease recurrence. Premenopausal patients had significantly shorter time from symptom manifestation to diagnosis (1.17 vs. 1.42 years perimenopausal vs. 2.08 years postmenopausal, p < 0.001), shorter time from diagnosis to index endoscopic airway dilation (1.90 vs. 2.50 vs. 3.76 years, p = 0.005), and higher number of procedures (1.73 vs. 1.20 vs. 1.08 procedures, p < 0.001). CONCLUSIONS: We demonstrate premenopausal patients may have a more aggressive disease variant than their peri- and postmenopausal counterparts. However, it is unclear as to whether this is related to reduced estrogen in the peri- and postmenopausal states or the age-related physiology of wound healing and inflammation, regardless of estrogen. LEVEL OF EVIDENCE: 3 Laryngoscope, 134:825-830, 2024.

Scedosporium Infection After Intralesional Steroid Injections for Idiopathic Subglottic Stenosis.

Intralesional steroid injections are commonly used to treat idiopathic subglottic stenosis and are believed to have minimal systemic effects. This case report presents an immunocompetent 67-year-old woman with idiopathic subglottic stenosis who developed Scedosporium apiospermum infection of the subglottis following in-office steroid injections, suggesting a potential risk for infection associated with this treatment. This highlights the need for further research to understand the impact of intralesional steroid injections on local and systemic immunocompetency to inform treatment protocols for idiopathic subglottic stenosis. Laryngoscope, 2024.

Impact of Procedural Variation in Endoscopic Dilation for Idiopathic Subglottic Stenosis.

OBJECTIVES: A small number of Idiopathic subglottic stenosis (iSGS) patients are treated at institutions across the country. Divergence in operative techniques for endoscopic dilation (ED) of iSGS has been anecdotally recognized but not formally characterized. Additionally, the relationship between procedural variation and clinical outcome has not been studied. METHODS: Secondary analysis of the NoAAC iSGS1000 cohort investigated variation in procedural techniques and treatment outcomes in patients treated with ED across high-enrolling treatment centers (enrolled >10 patients in PR-02 trial). RESULTS: Thirteen NoAAC centers each enrolled >10 patients treated with ED for a total of 281 subjects. There was significant variation in procedural details and rate of recurrence among institutions. Hierarchal cluster analysis revealed significant heterogeneity among institutions and clusters in all procedural variables. However, analysis demonstrated a transient delay in disease recurrence in cluster 2 which disappeared with longer longitudinal follow-up. Patient-reported outcome and peak expiratory flow data supported the potential benefit of the technical variation in Cluster 2. Distinct to cluster 2, however, was routine use of adjuvant triple medical therapy (proton pump inhibitor (PPI), antibacterial agent, and steroid inhaler). CONCLUSIONS: Both outcome and procedural technique vary among centers employing ED to treat iSGS. A transient delay in recurrence was observed among centers that routinely prescribed adjuvant medical therapy (antibiotic, inhaled corticosteroid, and PPI) to iSGS patients after endoscopic dilation, which was further supported by patient-reported data and peak expiratory flow data. Prospective studies are needed to understand the effects of adjuvant medical therapy on recurrence after endoscopic dilation. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:3260-3266, 2024.

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.

Navigating Pathways to Diagnosis in Idiopathic Subglottic Stenosis: A Qualitative Study.

OBJECTIVE: Idiopathic subglottic stenosis is a rare disease, and time to diagnosis is often prolonged. In the United States, some estimate it takes an average of 9 years for patients with similar rare disease to be diagnosed. Patient experience during this period is termed the diagnostic odyssey. The aim of this study is to use qualitative methods grounded in behavioral-ecological conceptual frameworks to identify drivers of diagnostic odyssey length that can help inform efforts to improve health care for iSGS patients. METHODS: Qualitative study using semi-structured interviews. Setting consisted of participants who were recruited from those enrolled in a large, prospective multicenter trial. We use directed content analysis to analyze qualitative semi-structured interviews with iSGS patients focusing on their pathways to diagnosis. RESULTS: Overall, 30 patients with iSGS underwent semi-structured interviews. The patient-reported median time to diagnosis was 21 months. On average, the participants visited four different health care providers. Specialists were most likely to make an appropriate referral to otolaryngology that ended in diagnosis. However, when primary care providers referred to otolaryngology, patients experienced a shorter diagnostic odyssey. The most important behavioral-ecological factors in accelerating diagnosis were strong social support for the patient and providers' willingness to refer. CONCLUSION: Several factors affected time to diagnosis for iSGS patients. Patient social capital was a catalyst in decreasing time to diagnosis. Patient-reported medical paternalism and gatekeeping limited specialty care referrals extended diagnostic odysseys. Additional research is needed to understand the effect of patient-provider and provider-provider relationships on time to diagnosis for patients with iSGS. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:815-824, 2024.

Comparison of Hemodynamics in Jet Ventilation vs. Intermittent Apnea for Airway Stenosis Surgery.

OBJECTIVE: The objective of this study is to assess the impact of two different ventilation techniques, jet ventilation and apneic anesthesia with intermittent ventilation (AAIV), on patient hemodynamics and operative time during endoscopic laryngotracheal stenosis surgery. METHODS: Retrospective chart review of patients who underwent airway dilation for laryngotracheal stenosis by a single surgeon at a single institution from October 1, 2000 through January 2, 2020. Logistic regression, Mann-Whitney U tests and chi square analysis were used to determine statistical significance. RESULTS: A total of 157 patients, 43 (27.4%) male and 114 (72.6%) female, and 605 total encounters were included for analysis. There were no significant differences in hemodynamic outcomes when comparing the AAIV and jet ventilation groups. Specifically, there was no significant difference in either peak end-tidal CO2 or nadir O2 saturation between the AAIV and jet ventilation groups (p = 0.4016) and (p = 0.1357), respectively. The patients in the AAIV group had a significantly higher median BMI 32.93 (27.40-39.40) compared with 28.80 (24.1-32.65) (p = 0.0001). Although not necessarily clinically significant, patients with higher BMI had lower median O2 nadirs (97.8%) than non-obese patients (99.2%) (p < 0.0001). The median total procedure time was equivalent when comparing the two ventilation techniques. CONCLUSION: AAIV is a safe method of ventilation for patients undergoing endoscopic laryngotracheal stenosis surgery with no significant differences in patient hemodynamics or procedure time when compared with jet ventilation. AAIV was the preferred method of ventilation for obese patients undergoing endoscopic laryngotracheal stenosis surgery. LEVEL OF EVIDENCE: 3 Laryngoscope, 134:1343-1348, 2024.

Idiopathic Subglottic Stenosis Is Associated With More Frequent and Abnormal Squamous Metaplasia.

OBJECTIVES: Gain insights into the pathophysiology of idiopathic subglottic stenosis (iSGS) by investigating differences in transcriptome of subglottic mucosal tissue between patients with iSGS and controls, and between tracheal and subglottic tissue within patients. METHODS: RNA sequencing was conducted on biopsied mucosal samples collected from subglottic and tracheal (in-patient control) regions in iSGS patients, and from subglottis in controls. The gene expression differences were validated on a protein level by (1) staining the tissue samples obtained from a second cohort of patients and controls; and (2) in vitro functional assays using primary subglottic epithelial cells from both iSGS patients and healthy donors. RESULTS: We found 7 upregulated genes in the subglottic region of iSGS patients relative to both the tracheal mucosa and subglottic region of controls. A gene ontology enrichment analysis found that the epithelial cell differentiation and cornification pathways are significant, involving specifically 3 of the genes: involucrin (IVL), small proline rich protein 1B (SPRR1B), and keratin 16 (KRT16). Involvement of these pathways suggests squamous metaplasia of the epithelium. Histological analyses of epithelium in subglottic mucosal biopsies revealed squamous metaplasia in 41% of the samples from iSGS patients and in 25% from controls. Immunohistochemical evaluation of the samples presented with squamous epithelium revealed increased expression of the protein encoded by SPRR1B, hyperproliferative basal cells, shedding of apical layers, and accompanying lesions in iSGS compared to CTRL. Cultured primary subglottic epithelial cells from iSGS patients had higher proliferation rates compared to healthy donors and squamous metaplastic differentiation formed thinner epithelia with increased expression proteins encoded by INV, SPRR1B, and KRT16, suggesting intrinsic dysfunction of basal cells in iSGS. CONCLUSIONS: Abnormal squamous differentiation of epithelial cells may contribute to the pathogenesis of iSGS. Patients having metaplastic epithelial phenotype may be sensitive to drugs that reverse it to a normal phenotype.

A Comprehensive Flow Cytometry Panel for Analysis of Idiopathic Subglottic Stenosis.

OBJECTIVE: To present a comprehensive flow cytometry panel for idiopathic subglottic stenosis (iSGS). STUDY DESIGN: Controlled ex vivo cohort study. SETTING: Tertiary care academic hospital in a metropolitan area. METHODS: Flow cytometry and single-cell RNA sequencing were performed on 9 paired normal and scar tissue samples from iSGS patients. Flow cytometry was used to assess the presence of myeloid (CD11b, CD14, CD15, Siglec8), lymphoid (CD3, CD4, CD8, gamma delta [γδ], FOXP3), endothelial (CD31), fibroblast (CD90, SMA), and epithelial (CD326, CK5) markers. RESULTS: On flow cytometry, iSGS scar is characterized by an increased presence of myeloid, lymphoid, endothelial, and fibroblast cell types, but a decreased presence of epithelial cells. In the myeloid lineage, iSGS scar samples demonstrated increased CD11b+ monocytes (P < .001), Siglec8+ eosinophils (P = .03), and CD14+ monocytes (P = .02). In the lymphoid lineage, iSGS scar demonstrated increased CD3+ T-cells (P < .001), CD4+ helper T-cells (P < .001), γδ+ T-cells (P < .001), and FOXP3+ regulatory T-cells (P = .002). iSGS scar exhibited specific increases in CD90+ (P = .04) and SMA+ (P < .001) fibroblasts but decreased CD326+ (E-cadherin) epithelial cells (P = .01) relative to normal samples. CONCLUSION: We present a comprehensive flow cytometry panel for iSGS. This flow panel may serve as a common platform among airway scientists to elucidate the cellular mechanisms underpinning iSGS and other upper airway pathologies. Scar iSGS samples demonstrate a distinct cellular profile relative to normal iSGS specimens, exhibiting increased fibroblast, endothelial, and inflammatory cell types but decreased epithelium.

An Ovine Model Yields Histology and Gene Expression Changes Consistent with Laryngotracheal Stenosis.

OBJECTIVES: Animal models for laryngotracheal stenosis (LTS) are critical to understand underlying mechanisms and study new therapies. Current animal models for LTS are limited by small airway sizes compared to human. The objective of this study was to develop and validate a novel, large animal ovine model for LTS. METHODS: Sheep underwent either bleomycin-coated polypropylene brush injury to the subglottis (n = 6) or airway stent placement (n = 2) via suspension microlaryngoscopy. Laryngotracheal complexes were harvested 4 weeks following injury or stent placement. For the airway injury group, biopsies (n = 3 at each site) were collected of tracheal scar and distal normal regions, and analyzed for fibrotic gene expression. Lamina propria (LP) thickness was compared between injured and normal areas of trachea. RESULTS: No mortality occurred in sheep undergoing airway injury or stent placement. There was no migration of tracheal stents. After protocol optimization, LP thickness was significantly increased in injured trachea (Sheep #3: 529.0 vs. 850.8 um; Sheep #4: 933.0 vs. 1693.2 um; Sheep #5: 743.7 vs. 1378.4 um; Sheep #6: 305.7 vs. 2257.6 um). A significant 62-fold, 20-fold, 16-fold, 16-fold, and 9-fold change of COL1, COL3, COL5, FN1, and TGFB1 was observed in injured scar specimen relative to unaffected airway, respectively. CONCLUSION: An ovine LTS model produces histologic and transcriptional changes consistent with fibrosis seen in human LTS. Airway stent placement in this model is safe and feasible. This large airway model is a reliable and reproducible method to assess the efficacy of novel LTS therapies prior to clinical translation. LEVEL OF EVIDENCE: N/A Laryngoscope, 2024.

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.

A novel technique of voice-sparing cricotracheal resection.

Background: Cricotracheal resection (CTR) is considered the standard of care for patients suffering from idiopathic subglottic stenosis (iSGS). Although CTR results in permanent restoration of airway patency, it has a mild to moderate impact on voice quality. Here we propose modifications of the standard CTR technique to make it a voice-preserving procedure. Methods: Five women with iSGS underwent voice-sparing CTR between January 2022 and January 2023. In this procedure, through several technical adaptations, the function of the cricothyroid joint was preserved. Outcomes of these voice-sparing CTRs were compared to outcomes in patients who underwent standard CTR in our institution. All patients underwent full functional preoperative and postoperative workups, including spirometry, voice measurements, patient self-assessment, and fiberoptic endoscopic evaluation of swallowing. Results: All 5 patients in the study group suffered from iSGS with high-grade Myer-Cotton III° stenosis (100%); 1 patient had previously undergone endoscopic laser resection. Voice evaluation demonstrated a nearly unchanged fundamental pitch (mean preoperative, 191 ± 73.1 Hz; postoperative, 182 ± 64.2 Hz) and dynamic voice range (preoperative, 24.4 semitones; postoperative, 20.4 semitones). This was in contrast to the control group, in which significantly reduced voice quality was observed. Conclusions: In selected patients suffering from iSGS, excellent functional results can be obtained with voice-sparing CTR.