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Laryngomalacia

last modified on: Mon, 09/25/2017 - 14:21

Laryngomalacia                                          

return to: Pediatric Airway

see also: The Evaluation of Stridor in Pediatric Patients

and:  Pediatric Airway Sizing

General: 

  1. Defined as the inward collapse of the supraglottic structures during inspiration, leading to partial occlusion of the airway. 
  2. Laryngomalacia is the most common cause of stridor in pediatric patients 
    1. Responsible for 65-75% of cases of stridor 
  3. The exact cause of laryngomalacia is still unknown and is an area of great interest, however, it is thought to be caused by a combination of three factors: 
    1. Redundant tissue in above the vocal folds
    2. Decreased neuromuscular control of the supportive cartilaginous structures of the airway
    3. Supraglottic edema due to laryngeal inflammation 
  4. Most cases of laryngomalacia resolve by 18-24 months, however, 10% will present with severe features requiring surgical intervention 

 

Epidemiology: 

  1. Laryngomalacia is the most common congenital abnormality of the larynx and the most common cause of stridor in pediatric patients 
    1. In a study of 205 pediatric patients presenting with the primary concern of stridor:
      1. Laryngomalacia was the cause in 75% of cases. (BLANK)  
  2. Males are 2x as likely to have laryngomalacia than females 
  3. Premature infants have a greater propensity to have poor neuromuscular control of the airway and are at increased risk 

 

Anatomy: 

  1. The epiglottis is formed from the 3rd and 4th branchial arches. 
  2. Overgrowth of the 3rd branchial arch structures leads to redundant tissue in the supraglottis. 
  3. Contrary to previous belief, patients with laryngomalacia do not have "soft cartilage."  
    1. Histologic studies of the cartilage in patients with laryngomalacia are indistinct when compared to patients without laryngomalacia. 

 

Pathophysiology: 

  1. Redundant tissue present in the supraglottis collapses to obstruct the airway during inspiration 
  2. Decreased area of the airway leads to increased resistance to air flow 
    1. Airway resistance is inversely proportional to the radius of the airway by a power of four.
  3. The velocity of the air increases as it passes the site of obstruction via the Venturi effect
  4. This increase in velocity creates a low-pressure vacuum at the site of obstruction, leading to further airway collapse via the Bernoulli Principal 
  5. Gastroesophageal Reflux Disorder (GERD) is commonly seen in patients with laryngomalacia 
    1. 65-100% of patients with laryngomalacia also have GERD
    2. Reflux and continued irritation of the laryngeal structures leads to tissue edema and further airway obstruction. 
    3. The velocity of the air increases as it passes the site of obstruction via the Venturi effect
    4. This increase in velocity creates a low-pressure vacuum at the site of obstruction, leading to further airway collapse via the Bernoulli Principal 
    5. Gastroesophageal Reflux Disorder (GERD) is commonly seen in patients with laryngomalacia 
      1. 65-100% of patients with laryngomalacia also have GERD
      2. Reflux and continued irritation of the laryngeal structures leads to tissue edema and further airway obstruction.                             
    6.                              Proposed Mechanism of Laryngomalacia

Classification: 

  1. Type I: Prolapse of the mucosa overlying the arytenoid cartilages
  2. Type II: Foreshortened aryepiglottic folds
  3. Type III: Posterior displacement of the epiglottis

  (Olney, et al. The Laryngoscope 1999. Used with permission from John Wiley and Sons)

Clinical Presentation: 

  1. The most common presenting symptom in laryngomalacia is inspiratory stridor.  
  2. Symptoms typically start during the first few weeks of life and resolve by 18-24 months of age. 
  3. Parents may report that the stridor is increased when the child is: 
    1. Supine
    2. Feeding
    3. Agitated 
    4. Crying 
  4. Infants may present with feeding difficulties such as: 
    1. Regurgitation, coughing, choking, and slow feedings.

 

Physical Exam: 

  1. The first step in evaluation of any patient with stridor is to assess for signs of respiratory collapse: 
    1. Cyanosis
    2. Intercostal, subxyphoid, and supraclavicular contractions 
    3. Nasal flaring
    4. Marked agitation 
  2. Assess the timing of stridor with the respiratory cycle 
    1. Inspiratory stridor is classically associated with supraglottic pathology (such as laryngomalacia)
    2. Expiratory stridor is associated with subglottic pathology 
    3. Biphasic stridor is seen in "fixed airway lesions", typically at the level of the vocal folds. 
  3. Evaluate for failure to thrive (weight for age that falls below the 5th percentile and/or weight deceleration that crosses two major percentile lines on the growth chart)
    1. Often due to difficulties with feeding and/or increased energy expenditure due to increased work of breathing.  

 

Diagnostic Testing: 

Flexible Fiberoptic Laryngoscopy: 

  1. Laryngomalacia is best diagnosed via flexible fiberoptic laryngoscopy in an awake patient 
    1. Sedation can promote the collapse of supraglottic structures, leading to a greater number of false-positives
  2. Flexible fiberoptic laryngoscopy may demonstrate: 
    1. Elongation and lateral extension of the epiglottis that collapses posteroinferiorly during inspiration
    2. Redundant arytenoids that collapse anteromedially during inspiration
    3. Shortening of the aryepiglottic folds, which leads to tethering of the arytenoids to the epiglottis
    4. Inward collapse of the aryepiglottic folds during inspiration
    5. The vocal cords demonstrate appropriate function and mobility 
  3. Up to 19% of patients with laryngomalacia will have additional synchronous lesions of the airway 
    1. Some investigators mandate direct laryngoscopy and bronchoscopy to identify these potentially life-threatening lesions.   
       

Direct Laryngoscopy: 

  1. Patients presenting with "severe features" should undergo direct laryngoscopy.
  2. Severe features include (Smith): 
    1. Severe respiratory distress 
    2. Failure to thrive 
    3. Recurrent pneumonia 
    4. Infants with symptoms that do not match their exam with FFL
    5. Synchronous lesions of the airway 
    6. Patients with laryngomalacia requiring surgical intervention 

Imaging:

Flexible fiberoptic laryngoscopy demonstrating classic 'omega-shaped' epiglottis in a patient suspected for laryngomalacia

 (Image property of Wikimedia Commons - released to public domain)

Management:

  1. The management of laryngomalacia depends on the severity of airway obstruction 
  2. Most cases resolve without surgical intervention by 18-24 months (90%). 


Medical Management: 

  1. Children with laryngomalacia should be serially assessed to ensure adequate weight gain.
    1. Airway collapse during feeding can lead to feeding difficulties and food aversion.  
    2. Chronically increased work of breathing can dramatically increase calorie consumption, especially in a newborn.
  2. Treatment of GERD 
    1. Use of weight-adjusted PPIs or H2 blockers reduces airway inflammation and edema:
      1. Eg: omeprazole 0.7 mg/kg/dose once daily or ranitidine 3 mg/kg 3 times a day
      2. Note that PPIs should not be used in premature infants until >40 weeks of age due to an increased risk for necrotizing enterocolitis (NEC).  
    2. Encourage upright feeding and bottles that minimize aerophagia to decrease the occurrence of reflux. 
    3. Providing small, frequent feedings and/or thickening of formula can decrease reflux symptoms. 
    4. 24 hour pH and impedance studies may be useful in assessing management in infants with refractory reflux symptoms despite maximum acid suppression dosing.  

Surgical Management: Surgical management is indicated in cases of airway compromise or in cases with severe features such as: 

  1. Life-threatening airway obstruction
  2. Refractory hypoxia/apneic episodes  
  3. Recurrent cyanosis 
  4. Cor pulmonale/pulmonary hypertension
  5. Failure to thrive 

 

Suggested Reading: 

  1. Daniel R. Olney; John H. Greinwald, Jr., MD; Richard J. H. Smith, MD; Nancy M. Bauman, MD. Laryngomalacia and its Treatment. The Laryngoscope. November 1999.