Pediatric Subglottic Stenosis Surgery Workup

Updated: Mar 28, 2018
  • Author: John E McClay, MD; Chief Editor: Ravindhra G Elluru, MD, PhD  more...
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Workup

Approach Considerations

Diagnosis of a patient with respiratory insufficiency and stridor can be quite complex. However, the fundamentals of a good history and physical examination cannot be overemphasized.  Sometimes, simply observing the patient at rest or during activity can provide valuable information regarding the severity of symptoms and the level of obstruction.

A patient with inspiratory stridor can have narrowing of the airway secondary to a static lesion of the upper airway as well as dynamic collapse of the airway. [9] Therefore, evaluation modalities must be designed to diagnose both types of narrowing of the airway. The mainstay for evaluating the airway for static and dynamic narrowing of the airway is endoscopy.

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Imaging Studies

The criterion standard for evaluation of the airway is direct laryngoscopy and direct bronchoscopy (see below). However, certain radiographic examinations can help in obtaining a diagnosis and determining the severity of the disease.

Usually, the initial radiographic study used to evaluate a child with airway obstruction is anteroposterior and lateral plain neck radiography. Frequently, in a child with subglottic stenosis (SGS), the subglottis appears narrowed and peaked; this is often described as a steeple sign. In a patient with a thin web SGS, lateral plain radiography may reveal a faint line.

Fluoroscopy is often performed in children with symptoms of dynamic airway obstruction.

Computed tomography (CT) and magnetic resonance imaging (MRI) are not often used in the primary evaluation of SGS, though they are sometimes useful as adjunctive diagnostic procedures to evalute for abnormal vasculature or mediastinal masses that may compress the airway.

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Endoscopy, Nasopharyngoscopy, Laryngoscopy, and Bronchoscopy

In a child with mild or moderate airway obstruction, perform flexible fiberoptic nasopharyngoscopy in the clinic or the emergency department (ED).

If extreme airway obstruction is observed or if an active supraglottic infectious process is suspected in a young child, flexible endoscopy may be deferred in favor of formal rigid bronchoscopy in the operating room (OR) so that the airway can be managed definitively and under controlled circumstances. However, flexible fiberoptic nasopharyngoscopy and bronchoscopy may be performed in a controlled setting in the OR, in that this allows better visualization of the dynamic nature of the airway and of possible dynamic collapse of the airway.  

Flexible fiberoptic nasopharyngoscopy and laryngoscopy

During flexible fiberoptic nasopharyngoscopy and laryngoscopy, topical anesthesia and decongestion can be accomplished in older infants and children with topical oxymetazoline and lidocaine. A 3-mm endoscope can be used, even in an infant. Pass the endoscope into both nasal cavities to access pyriform aperture stenosis, midnasal stenosis, choanal atresia or stenosis, lesions of the nose and nasopharynx, and the adenoid pad.

Pass the endoscope into the superior oropharynx and hypopharynx. The hypopharynx and larynx can be assessed. Identify the structure and position of the supraglottis. Evaluate the epiglottis and arytenoids for malacia or stenosis. Evaluate the position and movement of the true vocal cords. Evaluate edema or erythema of the true vocal cords, epiglottis, and arytenoids.

Flexible endoscopy

This can be performed with the patient in the supine or sitting position. The supine position often results in the obstruction of certain supraglottic processes. If the goal is to obtain the best visualization of the true vocal cords and supraglottis, place a child (even an infant) in the sitting position with his or her neck extended.

If the child is older, the voice can be evaluated, and videostroboscopy can be performed to assess the vocal cord waveform and vocal cord mobility.

Occasionally, the subglottis can be visualized with flexible endoscopy; however, rigid laryngoscopy and bronchoscopy are the safest procedures and offer the best visualization for the subglottis and tracheobronchial tree.

Rigid laryngoscopy and bronchoscopy

Rigid laryngoscopy with bronchoscopy is the best single test for evaluating airway obstruction in children, especially for static lesions such as SGS.

The otolaryngologist must have knowledge of the pediatric airway, and the OR must have adequate bronchoscopes and telescopes of various sizes. Prepare all equipment for bronchoscopy, including laryngoscopes, light sources, video documentation equipment, telescopes, and bronchoscopes before the child's arrival in the OR. Throughout the procedure, maintain good communication among anesthesiologists, surgical nursing staff, and physicians, so that any potential airway obstruction can be quickly assessed and addressed.

Do not further injure the pediatric airway. This point is of paramount importance. Use the smallest bronchoscope or telescope alone for evaluation of the subglottis in a child who does not require ventilation throughout the procedure. This practice allows good visualization without iatrogenic injury to the area. If ventilation is required throughout the evaluation, use a bronchoscope-telescope combination.

If a child has a tracheotomy or is not in extreme distress, he or she can breathe spontaneously and inhale oxygen and anesthetics through an endotracheal tube in the pharynx while the airways are visualized with a laryngoscope and large telescope. Frequently, the true vocal cords are anesthetized with lidocaine prior to evaluation to help prevent laryngospasm.

Determine the size of the child's airway by using endotracheal tubes. Myers and Cotton established a scale for SGS severity that is based on the child's age and the size of the endotracheal tube that can be placed in the airway with an air leak pressure of less than 20 cm H2O.

Evaluate the subglottis and glottis for fixation, scarring, granulation, edema, paralysis or paresis, and other abnormalities. Evaluate the distance and caliber of the stenosis. Apply the Myers and Cotton staging system only to circumferential SGS. Glottic stenosis and SGS often occur together and must be considered when reconstruction is planned.

Evaluate the maturity of the stenosis. If a firm white scar is present, the stenosis is mature. If the stenosis has a granular or erythematous appearance, gastroesophageal reflux (GER) disease (GERD), viral infection, allergic esophagitis, or another inflammatory process may be present.

Examine the area below the subglottis into the trachea and bronchi for secondary lesions. The suprastomal area is important because pathological stenosis or malacia can influence the choice of surgical procedure. In severe SGS, viewing the suprastomal area requires the passage of a tiny telescope through a narrow subglottis or a telescope or bronchoscope through a tracheotomy site, if available.

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Other Tests

Investigate any indication of GERD. Walner showed that children with SGS have a threefold increase in GERD as compared with the general pediatric population. [10]

Currently, the best test in evaluating for GER is dual-channel pH probe testing. One probe is placed above the lower esophageal sphincter, and another is placed at the area of the cricopharyngeus near the larynx.

Walner and Cotton recommend treating GER for 1 month before and 12 months after airway reconstructive surgery, even if only mild disease is present. [10, 11]  If moderate or severe GERD is diagnosed, start medical therapy and confirm disease resolution with another pH probe test prior to surgery.

Do not perform laryngeal reconstruction until GER has resolved. If reconstruction is being considered, pediatric laryngologists frequently perform tests to rule out GER, even in the absence of symptoms, because the disease may affect the outcome.

An "allergic" esophagitis may occur and may affect the outcome of surgery. To evaluate for this entity, esophagogastroduodenoscopy (EGD) is performed with biopsies of the proximal and distal esophagus, stomach, and duodenum. If more than 15 eosinophils are found in the mucosa per high power field, the patient may have "allergic" esophagitis. Evaluation and treatment for GERD must have taken place prior to this evaluation because reflux may elicit eosinophils as well.

If "allergic" esophagitis is discovered, then treatment with weeks to months of oral steroids or orally applied inhaled steroids is performed to help diminish the affects of the disease and possibly improve the success rate of laryngeal reconstruction.

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Staging

Myers and Cotton devised a classification scheme for grading circumferential subglottic stenosis on a scale of I to IV. The scale is based on a percentage of stenosis established by the age of the patient and the size of the endotracheal tube that can be placed in the airway with an air leak less than 20 cm H2O.

The percentage of stenosis is evaluated by using endotracheal tubes of different sizes. The largest endotracheal tube that can be placed with an air leak less than 20 cm H2O is recorded and evaluated against a scale that has previously been constructed by Myers and Cotton. This grading system mainly applies to circumferential stenosis and does not apply to other types of SGS or combined stenoses, although it can be used to obtain a rough estimate.

The four grades of the Myers-Cotton system are as follows:

  • Grade I - Obstruction of 0-50% of the lumen
  • Grade II - Obstruction of 51-70% of the lumen
  • Grade III - Obstruction of 71-99% of the lumen
  • Grade IV - Obstruction of 100% of the lumen (ie, no detectable lumen)

Evaluate the subglottis and the glottis for any fixation, scarring, granulation, edema, paralysis or paresis, or other abnormalities. Evaluate the distance and the caliber of the stenosis.

Only apply the Myers-Cotton staging system to circumferential SGS. Often, glottic stenosis and SGS occur together and must be considered in the planning of reconstruction.

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