Infants born prematurely can be intubated for a longer amount of time due to the fact that they have more flexible cartilage and a larynx located high in the airway. 90% of acquired cases in children are due to intubation, due to the ring of cartilage in the upper airway. Less commonly, infections, such as bacterial tracheitis, tuberculosis, histoplasmosis, diphtheria, and laryngeal papillomatosis can cause it. Systemic diseases, such as amyloidosis, granulomatosis with polyangiitis, sarcoidosis, inflammatory bowel disease, scleroderma, relapsing polychondritis, and polyarthritis, can also cause it. Other causes may include aspiration of foreign bodies, burns, and exposure to occupational hazards. Very rarely, the condition may also have no known cause, in which case it is known as idiopathic subglottic stenosis. Mechanism
High cuff pressure or long-term intubation can cause damage to the tracheal mucosa, causing inflammation, ulceration, and breakdown of cartilage. When the injury heals, scarring occurs, narrowing the airway. Treatment-related risk factors include repeated intubation, the presence of a nasogastric tube, and size of an endotracheal tube. Person-related risk factors include systemic diseases, the likelihood of infection, and inadequate perfusion. Acid reflux may cause narrowing due to scarring resulting from stomach acid damaging the tracheal mucosa. 10-23% of causes result due to narrowing arising from granulomatosis with polyangiitis. In these cases, it is believed that this is more common in people under the age of 20. Around 66% of sarcoidosis cases involve the airway. Diagnosis
CT scans and MRI (magnetic resonance imaging) can help in diagnosis.
Subglottic stenosis is a congenital or acquired narrowing of the subglottic airway. It can be congenital, acquired, iatrogenic, or very rarely, idiopathic. It is defined as the narrowing of the portion of the airway that lies between the vocal cords and the lower part of the cricoid cartilage. In a normal infant, the subglottic airway is 4.5-5.5 millimeters wide, while in a premature infant, the normal width is 3.5 millimeters. Subglottic stenosis is defined as a diameter of under 4 millimeters in an infant. Acquired cases are more common than congenital cases due to prolonged intubation being introduced in the 1960s. It is most frequently caused by certain medical procedures or external trauma, although infections and systemic diseases can also cause it. Signs and symptoms
Symptoms may range from stridor during exercise to complete obstruction of the airway. In idiopathic cases, symptoms may be mistaken for asthma. In congenital cases, symptoms occur soon after birth, and include difficulty breathing, stridor, and air hunger. If the vocal cords are affected, symptoms may include inability to make sound, and an unusual cry. Causes
Most commonly, acquired cases are caused by trauma or certain medical procedures. The condition is more often caused by external trauma in adults. External injuries occur from vehicular accidents or clothesline injuries. Iatrogenic cases can occur from intubation, tracheostomy, and an endotracheal tube cuff pressure that is too high. 17 hours of intubation in adults and 1 week of intubation in neonates can cause the injury.