Background: The causes of adult laryngeal and upper tracheal stenosis are trauma, chronic inflammatory diseases (amyloidosis, sarcoidosis, relapsing polychondritis), benign neoplasm (respiratory papillomatosis), malignant neoplasm (primary tracheal, secondary invasion, metastatic), and collagen vascular diseases (tracheopathia osteoplastica, Wegener granulomatosis). The most common cause of laryngotracheal stenosis continues to be trauma, which can be internal (prolonged endotracheal intubation; result of tracheotomy, surgery, irradiation; endotracheal burns) or external (blunt or penetrating neck trauma).

In the author’s experience, prolonged endotracheal intubation is the leading cause of laryngotracheal stenosis, which occurs mainly in patients with multiple trauma or in those who have undergone cardiovascular surgery.

In 1880, Macewen first reported endotracheal intubation for anesthesia and, in 1969, Lindholm reported injuries to the larynx and trachea after intubation for this purpose. Tracheal lesions caused by pressure from the cuff of the tube have now been almost eliminated with the use of high-volume, low-pressure cuffs. However, the number of intensive care patients who require intubation and artificial ventilation has increased dramatically.

Pathophysiology: The sequence of events that leads to stenosis involves ulceration of the mucosa and cartilage, inflammatory reactions with the granulation tissue, fibrous tissue formation, and contraction of fibrous scar tissue. Capillary perfusion pressure is a crucial consideration in mucosal injury. Mucosal ischemia is produced by direct contact with a segment of an endotracheal tube or by an increase in the pressure in the tube cuff.

The earliest laryngotracheal injury produced by an endotracheal tube is ulceration; basically, ulcer healing involves regeneration of the epithelium (primary healing) or repair (secondary healing). In the process of ulcer healing, if the epithelium fails to cover the granulation tissue, the growth of granulation tissue becomes exuberant. This tissue has 2 forms: pseudopapillary granulation and nodular granulation. After weeks or months, the granulation tissue that was once vascular becomes an almost avascular scar that contains only a few widely separated blood vessels.

Frequency:

• In the US:
  • Tracheal stenosis affects 4-13% of adults and occurs in 1-8% of neonates after prolonged intubation.

     

  • Primary tracheal tumors are rare.

     

  • Recurrent respiratory papillomatosis most commonly involves the larynx, but other areas of the respiratory tract may be involved. Tracheobronchial involvement usually is secondary to contamination after tracheotomy. Some authors consider them the most common benign laryngeal tumor.

     

  • Sarcoidosis involves the larynx in 5% of patients and the trachea in 1% of the cases, and remains a diagnosis of exclusion.

     

  • Laryngeal or tracheal involvement occurs in 50 to 70% of the patients with relapsing polychondritis.

     

  • In Wegener granulomatosis, tracheobronchial involvement occurs in 10 to 20% of the patients.

Mortality/Morbidity: Severe congenital laryngotracheal or benign acquired stenosis require immediate airway intervention, but fewer than half of the patients with congenital lesions require tracheotomy; they may seek medical care only after repeated episodes of laryngotracheal infections or with exercise intolerance.

Race: To the author’s knowledge, the prevalence does not depend on race.

Sex: To the author’s knowledge, the prevalence does not depend on sex.

Age: Postintubation tracheal stenosis in children is uncommon. Congenital stenosis is even more uncommon.

Anatomy: The trachea occupies the anterior and middle part of the neck and penetrates in the superior mediastinum behind the sternum. It begins at the level of the cricoid cartilage and ends at the level of the sternal angle, where it bifurcates to form the 2 main stem or primary bronchi. It has the shape of a cylindrical tube, with a flattened posterior wall. The skeletal structure of the trachea is composed of C-shaped hyaline cartilage (tracheal rings). None of the tracheal rings are complete; they all have a posterior opening filled with fibroareolar connective tissue and transversely oriented smooth muscle fibers.

The trachea has 2 depressions: a superior depression formed by the left thyroid lobule and an inferior depression near the bifurcation made by the aorta. The length of the trachea is about 12 cm in men and 11 cm in women, with a transverse diameter of 20 and 10 mm, respectively, in the anteroposterior direction. The lumen of the trachea is lined by a mucosa consisting of a thin lamina propria and a ciliated, pseudostratified columnar epithelium.

The superior and inferior thyroid, thymic, and right bronchial arteries provide the arterial supply of the trachea. The veins form rings that travel along the intercartilaginous spaces and flow into the esophageal and inferior thyroid veins. Tracheal innervation proceeds from the vagus nerve (pulmonary plexus and laryngeal nerves) and the sympathetic nerves (cervical and dorsal ganglia).

Surgical anatomy

The indications for tracheal reconstructive operations are primary tumors, secondary tumors (thyroid, bronchogenic, esophageal), postintubation lesions, and stenosis of many causes.

The anterior approach to the trachea is used for most benign lesions. Limiting the dissection to the anterior face of the trachea is very important to prevent injuring the recurrent laryngeal nerves and venous plexus, which are located lateral to the trachea. The anastomosis must be made without tension.

Clinical Details: Acquired benign stenoses may cause symptoms a few days to weeks after extubation. Frequently, symptoms develop after a latency period of months to years.

Symptoms of dyspnea may vary from a discrete wheezing to severe asphyxia. Stridor is noticed during inspiration and expiration.

Preferred Examination: A thorough history should be obtained, with a complete medical history directed toward previous airway intervention (intubation or tracheotomy) and head and neck, thoracic, or trauma surgery.

Complete evaluation of the airway requires a thorough knowledge of the anatomy and physiology. The larynx, hypopharynx, and proximal trachea are evaluated by means of indirect mirror examination, a 90° telescope, or flexible nasolaryngoscope. Endoscopic direct examination is the preferred method for diagnosis.

At laboratory examination, changes in serum electrolyte levels, the acid-base balance, blood oxygen level, and RBC count are observed in patients with tracheal stenosis.

At plain radiography, anteroposterior and lateral images of the upper airway are obtained by using a soft tissue protocol during both inspiration and expiration. These may be used to diagnose the cause of tracheal obstruction. Lateral and anteroposterior chest radiographs are also useful. High-resolution CT of the neck and thorax may be performed, and lung function may be analyzed.

Upper airway dysfunction in acute fulminant processes may be obvious on simple examination of the patient, but chronic subtle cases are difficult to diagnose.

Limitations of Techniques: Few contraindications to endoscopic examination exist; these include cervical spine disorders and coagulopathy. Patients who have significant airway compromise should not undergo flexible endoscopy unless rigid endoscopic equipment and a team is readily available to establish an adequate airway. Rigid laryngotracheobronchoscopy is useful for diagnosis and therapy, but it should be performed with general anesthesia. Flexible endoscopy is better for diagnosis, and it can be performed with local anesthesia.

Disadvantages of the CT include its cost, radiation exposure, and limitation to axial scans of the larynx and trachea. Also, CT provides only a static image.

DIFFERENTIALS

Airway Foreign Body
Asthma
Epiglottitis, Acute
Trachea, Stenosis

Other Problems to be Considered:

Patients who need prolonged endotracheal intubation and who present with a feeding problem have almost always been in a nothing-by-mouth status with the use of a nasogastric or nasojejunal tube. This tube adds to the internal trauma in the trachea by causing internal trauma to the esophagus, which can lead to the formation of a fistula between the 2 structures. This fistula must be identified by using endoscopy, dynamic radiographic imaging studies with a small volume of barium or water-soluble contrast agent, or CT.

X-RAY

Findings: Conventional plain films (ie, lateral and anteroposterior projections and images obtained with selective high-kV filtration techniques) of the larynx provide preliminary or definitive information about foreign bodies, trauma, and other types of acute and chronic airway obstruction. These radiographs can demonstrate soft-tissue swelling, alterations of the cartilaginous framework (if sufficiently calcified), and the position of the air column.

Xeroradiography, with its capacity for edge enhancement, can be used to clarify intrinsic soft-tissue detail (eg, calcifications), delineate masses and stenoses, sometimes depict cartilage abnormalities (eg, fractures, erosions), and identify foreign bodies by their type and location. Unfortunately, the radiation exposure with this technique is 3-5 times that of conventional radiography, and it is rarely used because of the high cost of leasing the equipment.

Degree of Confidence: The variability of calcification in the laryngeal cartilages can create a diagnostic problem.