Background

Laryngotracheal stenosis (LTS) refers to a fibrotic condition characterized by narrowing of the upper airway at the level of the larynx or trachea [1]. While commonly found in the larynx or proximal trachea, it can also manifest further down the airway. LTS presents a considerable challenge for otolaryngology specialists [2]. While in children, it may be either acquired or congenital, in adults and adolescents, it is predominantly acquired [1, 3]. Etiological factors include trauma, chronic inflammatory diseases, neoplasms, and collagen vascular diseases. LTS management remains intricate for otolaryngologists, encompassing endoscopic procedures, open laryngotracheal resection with anastomosis, and laryngotracheal reconstruction [4, 5].

This study aims to present the experience of Tunisian ENT surgeons in managing a series of acquired LTS cases, shedding light on current diagnostic methods and therapeutic approaches for acquired LTS.

Methods

A retrospective analysis was conducted at the ENT Department of Farhat Hached University Hospital, spanning from 1994 to 2020. The study encompassed patients with a history of prolonged intubation [7–31 days] or tracheostomy, who presented with symptoms of dyspnea or stridor. Cases involving congenital or tumoral stenosis, as well as those with incomplete medical records, were excluded. The study enrolled a total of 48 patients diagnosed with acquired laryngotracheal stenosis.

Diagnostic evaluation for LTS consisted of fiber-optic laryngoscopy followed by direct laryngoscopy and bronchoscopy. In cases of severe LTS, a CT scan of the larynx and trachea was performed. The severity of stenosis was assessed using the Myer-Cotton classification, which categorizes obstruction as grade 1 (up to 50% obstruction), grade 2 (51–70% obstruction), grade 3 (71–99% obstruction), and grade 4 (no detectable lumen). All patients underwent routine blood investigations. Treatment approaches included endoscopic tracheal dilations for stenosis, open surgical resection with end-to-end anastomosis, and definitive tracheostomy.

Results

Throughout the study duration, a total of 48 patients were incorporated into the analysis, consisting of 36 males and 12 females. The average age of the cohort was 24 years, with the youngest patient being 19 years old and the oldest patient being 65 years old.

Endotracheal intubation was incriminated in all patients. The most common indications of intubation were trauma and complications of acute or chronic diseases (Table 1).

Table 1 The reasons for intubation
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Out of the total, 22 patients (66%) exhibited a history of extended intubation, while 16 patients (34%) had a history of both prolonged intubation and tracheostomy. The average duration of intubation was 14 days. Initial assessment was conducted using rigid tracheoscopy and bronchoscopy, with a CT scan performed in 34 patients.

In terms of the stenosis location, 28 cases (58%) were identified as tracheal stenosis, while 20 cases (42%) involved subglottic stenosis. Notably, none of the cases exhibited supraglottic stenosis. The average length of the stenotic segment was approximately 2.3 cm, with 64% of cases showing a segment length of up to 1 cm. The stenosis pattern was concentric and hourglass-shaped in 46 patients, while 2 patients exhibited an eccentric narrowing (Fig. 1).

Fig. 1
figure 1

CT Scan showing a case of post-intubation tracheal stenosis: coronal (A), sagittal (B) and VRT images show a focal short segment concentric narrowing of the tracheal wall giving an “hourglass” configuration (arrow)

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VRT: volume rendering technique

The degree of stenosis displayed a range of 10% to 90%, with an average of 56%. Stenosis severity was categorized as grade 1 (40%), grade 2 (35%), and grade 3 (25%) based on the Meyer-Cotton classification. No cases fell under grade 4.

Ten patients (20.83%) had undergone tracheostomy before their presentation, while six additional patients required emergency tracheostomies in our department. A substantial majority, 42 patients (87.5%), underwent endoscopic interventions. The period from symptom onset to endoscopic intervention varied between 1 and 21 months.

Direct laryngoscopy and rigid bronchoscopy were performed to evaluate the characteristics of the stenotic segment, revealing a fibrotic nature in 19 patients (39.58%), inflammatory attributes in 21 patients (43.75%), and mixed features in 2 cases (4.17%).

In total, 17 patients (35.41%) underwent successful curative endoscopic dilatation, while others received alternative treatments. Among these, 15 underwent additional surgical procedures, and 10 had a T-tube insertion. Multiple endoscopic dilatations were required, with an average of 4 sessions (range 1 to 19).

T-tube placement was implemented in 10 patients (20.8%), with tube retention spanning 6 to 24 months (mean 15 months). Successful decannulation was accomplished in 9 patients (90%), with one patient unable to undergo the procedure.

Surgical intervention was conducted in 19 cases, involving laryngotracheal resection with end-to-end anastomosis. The procedures included crico-tracheal anastomosis in 6 instances and tracheal anastomosis in 13 cases (Figs. 2 and 3).

Fig. 2
figure 2

A preoperative view: the thyroid isthmus is divided and ligated. The anterior trachea is exposed and the stenotic cervical tracheal segment is exposed (white arrow) and then resected (yellow arrow) with end-to-end anastomosis (orange-yellow)

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Fig. 3
figure 3

Image of the resected segment of the trachea showing a concentric LTS

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A cervical approach was employed for the surgical procedure in all patients, without any instances of open laryngotracheal reconstruction. The mean count of resected rings totaled 4 (ranging from 3 to 6 rings).

Several complications emerged within our study cohort (Table 2).

Table 2 Table illustrating postoperative complications in our study
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Two patients (4.16%) experienced skin excoriation, while tube blockage due to crust formation occurred in 5 patients (10.41%). Additionally, granulomas resulting from foreign body reactions were identified in 2 patients (4.16%), and one case reported restenosis. No fatalities were recorded during the course of this retrospective study. The average duration of follow-up was 3 years, with a ± 6 months.

Discussion

Laryngotracheal stenosis (LTS) encompasses the narrowing of the upper airway involving both the laryngeal and tracheal segments [1, 4]. This condition, whether partial or complete, presents intricate configurations and has seen an increase in incidence. Acquired cases predominantly stem from patients admitted to intensive care units necessitating extended endotracheal intubation and tracheostomy [6, 7]. Key sites of stenosis typically include the endotracheal tube cuff region and tracheostomy site [5]. Although prolonged intubation stands as the primary cause, other etiologies should be explored, ranging from infectious to neoplastic to autoimmune origins [1, 5, 8, 9]. Despite the life-saving nature of intubation and tracheostomy, their cautious employment is advised [5, 8].

The elevated pressure from the endotracheal tube balloon induces LTS by triggering mucosal ischemia. Subsequent tracheal wall necrosis leads to tissue scarring and stenosis. It is often advised to maintain the balloon pressure within a range of 20 to 30 cmH2O (centimeters of water) to minimize the risk of complications. Symptoms of airway compromise ensue [5, 9]. Initial symptoms, including voice alterations, stridor, cough, and dyspnea, often develop after a period of asymptomatic incubation, with varying duration [4, 9].

For managing LTS, meticulous clinical and endoscopic evaluations are essential. Diagnostic protocols encompass imaging and endoscopic assessments [10]. Conventional endoscopy serves as the gold standard for LTS characterization, although its efficacy might decline with tight strictures [11]. Common imaging findings include localized tracheal wall narrowing that imparts a characteristic hourglass shape [10, 11]. CT scans provide data on stenosis grade, number, length, and distance from vocal cords [3, 10, 11]. CT virtual bronchoscopy is a valuable tool for assessing the trachea and bronchi. It is a non-invasive imaging technique that uses computed tomography (CT) data to create three-dimensional visualizations of the inside of the airways [3, 10, 11].

Grading systems for LTS abound, with the widely accepted Myer-Cotton grading system being internationally recognized [4, 10]. It quantifies stenosis percentage based on air leak relative to the endotracheal tube size, dividing subglottic airway stenosis into four grades.

Management options aim to restore optimal airway function [12,13,14]. The chosen method hinges on patient factors and procedure benefits. Endoscopic interventions encompass mechanical dilation, cold steel or CO2 laser excision, balloon dilation, mitomycin C application, conducted via flexible or rigid bronchoscopy [7, 13, 15,16,17]. This approach suits grade I or II LTS with a stenotic segment < 1 cm, but proves less effective for circumferential scarring, longer stenotic segments, or cartilage loss (e.g., tracheomalacia), and is favored for high anesthetic risk patients [18, 19].

Surgical interventions cater to patients in good general condition, executed post-resolution of edema and inflammation to ensure optimal anastomotic outcomes [13, 14, 20]. Tracheal resection with end-to-end anastomosis is ideal for localized cervical tracheal stenosis, with tension-free anastomosis crucial for preventing detachment [20, 21]. Crico-tracheal resection with end-to-end anastomosis boasts moderate success, though anastomotic release risk raises uncertainty [20, 22]. In cases of anastomotic site re-stenosis post-surgery, endoscopic procedures may optimize final results [20, 22, 23].

Conclusion

Management of laryngotracheal stenosis is a challenging problem that demands a multidisciplinary approach. The appropriate treatment option should be discussed depending on the pathology, the location and the length of the stenotic segment, the experience of the medical staff, and the general condition of the patient. Prevention is essential and multiple precautions should be considered like the use of high volume, high tracheostomy, and prolonged intubation.