Chapter 380 Laryngotracheal Stenosis and Subglottic Stenosis
Laryngotracheal stenosis is the most common cause of airway obstruction requiring tracheostomy in infants. The glottis (vocal cords) and the upper trachea are also compromised in most laryngeal stenoses, particularly those that develop following endotracheal intubation. Subglottic stenosis is considered to be congenital when there is no other apparent cause such as a history of laryngeal trauma; approximately 90% of cases manifest in the 1st yr of life.
380.1 Congenital Subglottic Stenosis
Biphasic or primarily inspiratory stridor is the typical presenting symptom for congenital subglottic stenosis. Recurrent or persistent croup usually occurs in these children at 6 mo of age or younger. The edema associated with an upper respiratory tract infection or laryngopharyngeal reflux events compromises the underlying narrowed airway.
Treatment is dictated by the severity of the obstruction and is the same as acquired subglottic stenosis. Because most cases of congenital stenosis are cartilaginous, dilatation or laser surgery are not uniformly effective. Anterior laryngotracheal decompression (cricoid split) or laryngotracheal reconstruction with cartilage grafting usually avoids tracheostomy.
380.2 Acquired Laryngotracheal Stenosis
Ninety percent of acquired stenoses are associated with endotracheal intubation, although with improved ventilatory support, the incidence of this complication is decreasing. Studies published after 1983 reported an incidence of neonatal subglottic stenosis of <4.0%, and those after 1990 reported an incidence of <0.63%. When the pressure of the endotracheal tube against the mucosa is greater than the capillary pressure, ischemia occurs, followed by necrosis and ulceration. Secondary infection and perichondritis develop with exposure of cartilage. Granulation tissue forms around the ulcerations. These changes and edema throughout the larynx usually resolve spontaneously after extubation. Chronic edema and fibrous stenosis develop in only a small percentage of cases. A number of factors predispose to the development of laryngeal stenosis. Laryngopharyngeal reflux of acid and pepsin from the stomach exacerbates endotracheal tube trauma. More damage is caused in areas left unprotected, owing to loss of mucosa. Congenital subglottic stenosis narrows the larynx and significant injury is more likely to occur with use of an endotracheal tube of age-appropriate size. Other patient factors include sepsis and infection, dehydration, malnutrition, chronic inflammatory disorders, and immunosuppression. An oversized endotracheal tube is the most common factor contributing to laryngeal injury. A tube that allows a small air leak at the end of the inspiratory cycle minimizes potential trauma. Other extrinsic factors—traumatic intubation, multiple reintubations, movement of the endotracheal tube, and duration of intubation—can contribute to varying degrees in individual patients.
Symptoms of acquired and congenital stenosis are similar. Spasmodic croup, the sudden onset of severe croup in the early morning hours, is usually due to laryngopharyngeal reflux with transient laryngospasm and subsequent laryngeal edema. These frightening episodes resolve rapidly, often before the family and child reach the emergency department.
The diagnosis is confirmed by direct laryngoscopy and bronchoscopy. High-resolution CT imaging is of limited value.
The severity, location, and type (cartilaginous or soft tissue) of the stenosis determine the treatment. Mild cases can be managed without operative intervention because the airway will improve as the child grows. Moderate soft tissue stenosis is treated by endoscopy using gentle dilations or CO2 laser. Severe laryngotracheal stenosis is likely to require laryngotracheal expansion surgery or resection of the narrowed portion of the laryngeal and tracheal airway (partial cricotracheal resection). Every effort is made to avoid tracheotomy using endoscopic techniques or open surgical procedures.
Benjamin B, Holinger LD. Laryngeal complications of endotracheal intubation. Ann Otol Rhinol Laryngol. 2008;117(Suppl 200):1-20.
Markovitz BP, Randolph AG, Khemanu RG: Corticosteroids for the prevention and treatment of post-extubation stridor in neonates, children and adults, Cochrane Database Syst Rev (2)CD001000, 2008.
Rizzi MD, Thorne MC, Zur KB, et al. Laryngotracheal reconstruction with posterior cartilage grafts. Otolaryngol Head Neck Surg. 2009;140:348-353.
Walner DL, Loewen MS, Kimura RE. Neonatal subglottic stenosis—incidence and trends. Laryngoscope. 2001;111:48-51.