Laryngeal Stenosis Workup

• Few diagnostic laboratory findings are found in glottic stenosis, although, in older children, granulomatous and systemic diseases may be considered.
• Perform serologic workup for sarcoidosis, Wegener granulomatosis, or rheumatoid arthritis if these conditions are considered.
• Perform routine preoperative laboratory studies if open reconstruction is planned.

• Lateral soft tissue radiographs of the neck allow an assessment of the general structure of the larynx, approximate size of the airway column, and the length of stenosis. High-kilovoltage anteroposterior projections of the neck allow an assessment of the subglottic airway. Narrowing of the air column should not be confused with the normal right lateral deviation of the trachea just below the thoracic inlet from the aortic arch on the left. Plain films are useful in the diagnosis of retropharyngeal abscess, croup, and epiglottitis.
• Airway fluoroscopy may be useful if true inspiratory and expiratory views are difficult to obtain.
• Obtain chest radiographs in all patients with airway abnormalities to help define concomitant cardiopulmonary problems.
• A CT scan allows an evaluation of the laryngeal framework and length of stenosis. CT scan and MRI are not routinely ordered unless specific information is required after evaluation of the airway by rigid endoscopy. Recent reports describe the use of helical CT imaging on a double-detector helical CT system with sagittal multiplanar and volume-rending reformations and with axial cross-sectional stenotic areas determined. Symptoms were found to have a high degree of correlation with radiologic findings. Care must taken to avoid undervaluing the degree of stenosis using 2-dimensional algorithms.
• Barium esophagram may be indicated to assess feeding problems but rarely rules out external compression of the trachea, as might be the case from vascular anomalies. Other congenital lesions such as lymphatic malformations or duplication cysts may case external compression and secondary tracheomalacia.

• Pulmonary function tests reveal characteristic changes in upper airway stenosis, and may be used to compare the postoperative results with preoperative figures. These tests are not essential to preoperative workup, as reliable data are difficult to obtain in children. In the institutions equipped with facilities for pulmonary function testing in infants and young children, the tidal or forced flow volume loop may show abnormalities such as truncation of inspiratory and/or expiratory component suggesting obstruction. The extent of truncation changes after surgical correction.
• Voice and speech evaluation is performed when possible.
• Genetic testing if indicated. Velocardiofacial syndrome has been associated with anterior glottic webs.

• Flexible fiberoptic endoscopy in the awake patient is performed to assess for supraglottic and glottic pathology such as vocal cord paralysis and laryngomalacia.
• Direct laryngoscopy and bronchoscopy with the patient under general anesthesia remains the criterion standard of diagnosis by allowing careful evaluation of each segment of the airway: supraglottis, glottis, subglottis, and trachea. The outer diameter of the largest bronchoscope that can pass through the stenosis should be noted as well as the length of the stenotic segment, its location, thickness, and composition. Use of the telescope without the bronchoscope allows dynamic assessment. Rule out secondary sites of stenosis and palpate arytenoids for cricoarytenoid joint fixation. Laryngeal electromyography may be useful.
• Determine the size of the airway visually and objectively by using endotracheal tubes. An individual’s endotracheal tube size is the largest tube that permits an air leak at less than 30 cm of water pressure.
• Evaluate for gastroesophageal reflux (pH probe) in all surgical candidates.
• Assess vocal status (with the assistance of speech pathologists) preoperatively in older children and adults.

Subglottic stenosis may be histopathologically classified as cartilaginous or membranous. The latter may be due to submucosal fibrosis, submucosal gland hyperplasia, or granulation tissue.

Rarely, when laryngeal stenosis is caused by granulomatous infections or systemic diseases, biopsy is necessary to make the diagnosis. For example, the presence or absence of caseating necrosis or vasculitis differentiates between tuberculosis, sarcoidosis, and Wegener granulomatosis. Identification of causative organisms can also be accomplished using the biopsy specimen.

Regarding acquired stenosis due to iatrogenic trauma, histologically, studies suggest that collagen type I may be responsible for the structural integrity of normal tracheal and cricoid rings since in stenosis resection specimens, increased amounts of collagen type II are found deposited by regenerative fibroblasts, lowering the ratio of collage type I to type II.

The classification of glottic webs as described by Cohen is as follows:

• Type I is an anterior web involving 35% or less of the glottis with visible true cords and no subglottic extension. Airway and voice symptoms are mild.
• Type II is an anterior web involving 35-50% of the glottis. Minimal involvement of subglottis. Mild airway and voice symptoms.
• Type III is an anterior web involving 50-75% of the glottis with associated cricoid abnormalities. True vocal cords may not be visualized. Severe airways symptoms with marked vocal dysfunction. Airway intervention may be necessary.
• Type IV is a web occluding 75-90% of the glottis. True vocal cords are not identifiable. Subglottis is narrowed. The patient is aphonic. Immediate airway management is required.
• Posterior glottic stenosis may be defined as one of the following 4 types: (Bogdasarian and Olson).

  • Type I is vocal process adhesion from an interarytenoid scar with a mucosally lined posterior sinus tract.
  • Type II is a posterior commissure stenosis involving the submucosa of the posterior commissure, interarytenoid region, and internal surface of the posterior cricoid lamina.
  • Type II and IV stenosis are posterior commissure scars involving the cricoarytenoid joint unilaterally or bilaterally, respectively.
• The Myer-Cotton Grading system for subglottic stenosis is the most frequently used and is based on the leak pressure, tube size, and age of the patient, as follows:

  • Grade I - Less than 50% laryngeal lumen obstruction
  • Grade II - 50-70% obstruction
  • Grade III - 71-99% obstruction with an identifiable lumen present
  • Grade IV - Complete obstruction; no lumen present