Idiopathic subglottic stenosis, also known as Idiopathic laryngotracheal stenosis or ILTS, is a narrowing of the portion of the trachea below the glottis (voice box).
Congenital stenosis has two main types, membranous and cartilaginous.
In membranous stenosis, fibrous soft tissue thickening is caused by increased connective tissue or hyperplastic dilated mucus glands with absence of inflammation. Membranous stenosis is usually circumferential and may extend upward to include the true vocal folds.
In cartilaginous stenosis, a thickening or deformity of the cricoid cartilage most commonly occurs, causing a shelflike plate of cartilage and leaving a small posterior opening. Cartilaginous stenosis is less common than membranous stenosis.
Source: Medscape, Rightdiagnosis
- Narrowed trachea below voice box
- Breathing difficulty due to obstructed airway
- Swallowing difficulty
- Recurring croup in children
- Asymptomatic in mild cases
- Intubation is difficult
- Recurring pneumonitis
Stenosis is said to be congenital in the absence of a history of intubation or other acquired causes. Congenital laryngeal webs account for approximately 5% of congenital anomalies of the larynx, with 75% occurring at the glottic level and the rest occurring at the subglottic or supraglottic level. Most severe cases are diagnosed in childhood.
Trauma is the most common cause of stenosis in both children and adults. Approximately 90% of all cases of acquired chronic subglottic stenosis in children and adults result from endotracheal intubation. The reported rate of stenosis following intubation ranges from 0.9-8.3%.
Stenosis could also be secondary to foreign body, infection, inflammation, or chemical irritation. Respiratory epithelium is susceptible to injury. Initial edema, vascular congestion, and acute inflammation can progress to ulceration and local infection with growth of granulation tissue. Finally, fibroblast proliferation, scar formation, and contracture can occur and result in stenosis.
Other causes include the following:
- External trauma, penetrating and blunt
- Tracheotomy, especially a high tracheotomy or cricothyroidotomy
- Percutaneous tracheotomy (This has an emerging role as a cause.)
- Chondroradionecrosis after radiation therapy; may occur up to 20 years later
- Chronic infection
Adults with mild congenital stenosis are usually asymptomatic, and they are diagnosed after a difficult intubation or while undergoing endoscopy for other reasons.
Patients with acquired stenosis are diagnosed from a few days to 10 years or more following initial injury. The majority of cases are diagnosed within a year.
This type of stenosis almost exclusively involves women. Systemic factors may increase the risk of injury and include the following:
- Gastric acid reflux
- Chronic illness
- Immunocompromised patient
- Poor perfusion
- Radiation therapy
In most of the cases, surgery has become one of the most common indications for tracheal resection and reconstruction. Methods of single-stage resection and reconstruction have been developed.
Indications for treatment are to improve compromised airways and progress toward decannulation. Speedy intervention prior to cartilage damage or scar contracture is preferred when the diagnosis is made early.