Key points

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Introduction: nature of the problem

Laryngomalacia is the most common congenital laryngeal anomaly and accounts for 60% to 70% of cases of stridor in neonates and infants. The physical finding of stridor is a manifestation of upper airway obstruction caused by collapse of the supraglottic tissue because of excess mucosa, and abnormal and/or reduced laryngeal tone. Symptoms generally become apparent after the first 2 weeks of life, and, in most cases, resolve between 12 and 18 months of age. Most cases resolve with minimal or no treatment; approximately 10% of cases require surgical intervention.

The term laryngomalacia, or soft larynx in Latin, replaced the more antiquated term congenital laryngeal stridor, which had previously been used to describe the condition. First coined by Jackson and Jackson in 1942, the term differentiated the condition from other causes of stridor and more clearly depicted the flaccidity of the larynx.

Introduction: nature of the problem

Laryngomalacia is the most common congenital laryngeal anomaly and accounts for 60% to 70% of cases of stridor in neonates and infants. The physical finding of stridor is a manifestation of upper airway obstruction caused by collapse of the supraglottic tissue because of excess mucosa, and abnormal and/or reduced laryngeal tone. Symptoms generally become apparent after the first 2 weeks of life, and, in most cases, resolve between 12 and 18 months of age. Most cases resolve with minimal or no treatment; approximately 10% of cases require surgical intervention.

The term laryngomalacia, or soft larynx in Latin, replaced the more antiquated term congenital laryngeal stridor, which had previously been used to describe the condition. First coined by Jackson and Jackson in 1942, the term differentiated the condition from other causes of stridor and more clearly depicted the flaccidity of the larynx.

The infant larynx: anatomic considerations

A review of laryngeal anatomy aids in the understanding of pathophysiology in laryngomalacia. The structure of the larynx is divided into 3 areas: the supraglottis, glottis, and subglottis. Laryngomalacia affects the supraglottic structures, which include the portions of the larynx above the level of the vocal cords. Important supraglottic structures that can be involved in laryngomalacia include the epiglottis, arytenoid cartilages, and aryepiglottic folds (which connect the epiglottis to the arytenoids).

Neonatal and infantile larynges have several important differences from those of older children and adults. At birth, the position of the larynx is higher than in older children and adults. The growth of the larynx is accelerated during the first 3 years of postnatal life and gradually achieves its final shape. Postnatal descent of the hyoid and larynx is unique to humans. The high position of the larynx at the time of birth facilitates transition to spontaneous breathing and prevention of aspiration, and this also accounts for obligate nasal breathing in neonates. The descent of the larynx is crucial for appropriate development of speech. Major postnatal changes to the larynx occur in the first year of life.

The infantile epiglottis is longer than the laryngeal length in older children, which may predispose it to posterior displacement. The cartilage of the infantile larynx is also more pliable than that of the larynx later in life, a property that has been proposed to play a role in the collapsibility of the laryngeal airway.

Clinical presentation

Inspiratory stridor is the primary feature of laryngomalacia. Characterized by a harsh, high-pitched sound, stridor as it presents in laryngomalacia often worsens while the infant is supine, feeding, or crying. Feeding difficulties also often accompany the presence of stridor in patients with laryngomalacia, because the delicate balance between the suck-swallow sequence and respiration is often disrupted. Coughing, choking, regurgitation with feedings, and slow oral intake are all common symptoms. There is thought to be a close relationship between laryngomalacia and gastroesophageal/laryngopharyngeal reflux, although the exact mechanism has yet to be fully elucidated.

Other causes of stridor must also be considered when evaluating a patient with these symptoms ( Table 1 ). One of the most useful ways to differentiate between causes of noisy breathing is to identify in which phase of the respiratory cycle the sound is heard. Different causes of airway obstruction can lead to stridor during different phases of respiration: inspiration, expiration, or both (biphasic).

Stridor present during inspiration is usually caused by partial obstruction at the level of the supraglottic tissues. Variable extrathoracic obstruction results in primarily inspiratory stridor. During inspiration, atmospheric pressure is greater than extrathoracic intraluminal airway pressure, leading to collapse of supraglottic structures. During the expiratory phase, the exhalatory breath increases extrathoracic airway pressure such that it overcomes the collapse. Stridor primarily present during expiration is usually caused by obstruction in the lower tracheal airway. Negative intrathoracic pressure during inspiration allows air movement into the lungs, but the increase in intrathoracic pressure during expiration causes affected portions of the tracheal airway to collapse, leading to expiratory stridor.

Work-up: patient history

A complete patient history should be obtained when evaluating a patient with stridor. History should include a focus on antenatal and perinatal events, as well as current symptoms ( Table 2 ).

Work-up: physical examination

A complete physical examination should be performed, taking special note of the following:

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  Vital signs

  
  
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  Weight

  
  
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  General appearance

  
  
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  Presence of upper airway sounds and their timing within the respiratory cycle

  
  
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  Work of breathing, such as the presence of suprasternal retractions or abdominal muscle usage

  
  
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  Auscultation of lung fields

  
  
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  Chest wall structural abnormalities (eg, pectus excavatum)

Work-up: diagnostic testing

When laryngomalacia is suspected, diagnosis is confirmed with flexible fiberoptic laryngoscopy ( [CR] ). Flexible laryngoscopy can, in most cases, be performed easily in the otolaryngologist’s office or at the bedside without sedation. A small, flexible fiberoptic endoscope is passed from the child’s nostril through the nasal cavity and is positioned just above the larynx, allowing observation of the dynamic states of the larynx. Topical anesthetic such as lidocaine has been shown to exaggerate laryngomalacia and should not be used during flexible laryngoscopy in patients suspected to have the disease. Flexible fiberoptic laryngoscopy has been found to have good reliability (88%) for diagnosis of laryngomalacia, regardless of physician experience.

The key findings on flexible laryngoscopy, which may be present in any combination, are:

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  A tightly curled, omega-shaped epiglottis

  
  
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  Retroflexion (posterior displacement) of epiglottis

  
  
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  Short aryepiglottic folds

  
  
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  Redundant, prolapsing arytenoid mucosa and cartilage

Formal direct laryngoscopy and bronchoscopy under general anesthesia is not necessary in every patient with findings of laryngomalacia on flexible endoscopy. Most patients only require confirmation of diagnosis by flexible endoscopy alone. Rigid direct laryngoscopy should be performed in the following situations:

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  Absence of any abnormality in a patient with clinical stridor

  
  
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  When the symptom severity does not correlate with laryngoscopic examination, raising suspicion for another cause or secondary lesion

  
  
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  Clinical signs and symptoms of severe disease, in patients for whom surgical intervention is considered

  
  
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  Significant aspiration symptoms that cause concern for a posterior laryngeal cleft or tracheoesophageal fistula

Other diagnostic tests may be considered, including modified barium swallow or functional endoscopic evaluation of swallowing, particularly if concern for aspiration exists. In addition, esophageal pH probe studies should be considered if moderate to severe laryngomalacia symptoms persist despite antireflux treatment. Some investigators propose formal pH studies on all patients with laryngomalacia.