Airway malacias

Airway malacias are a group of conditions characterized by softening or weakening of the airway cartilage resulting in increased collapsibility of the larynx, trachea, and/or bronchi, which can cause respiratory symptoms. Laryngomalacia refers to the congenital weakening of the laryngeal cartilage and is the most common type of airway malacia. Tracheomalacia refers to the weakening of the tracheal cartilage or posterior membrane and can be congenital (often in association with other congenital syndromes) or acquired. Visualization of the airway (e.g., laryngoscopy, bronchoscopy) is the test of choice to diagnose airway malacias. Management of asymptomatic patients or patients with mild symptoms is conservative. Patients with severe symptoms generally require surgery.

Definition

• Collapse of supraglottic structures during inspiration due to anatomical and/or functional abnormalities

Epidemiology ^[1]

• Most common cause of congenital stridor (cause of stridor in 45–75% infants)
• Most common congenital anomaly of the larynx

Etiology

• Almost always congenital
• Most likely due to an underdeveloped nervous system

Pathophysiology

• Congenital abnormality of laryngeal cartilage → ↑ laxity and collapse of supraglottic structures during inspiration → airway obstruction

Clinical features

• Symptoms typically begin within the first 2 months of life and peak at 6–8 months.
• Inspiratory stridor: worsens in the supine position, during crying, upper respiratory tract infections, agitation, and feeding
• Feeding difficulties (e.g., regurgitation, emesis)
• Approx. 60% of affected children have concomitant GERD ^[2]
• Severe course: failure to thrive, obstructive sleep apnea, cyanosis

Diagnostics

• Flexible laryngoscopy (gold standard)
  • Direct visualization of the airway
  • Collapse of supraglottic structures during inspiration and an omega-shaped epiglottis. ^[3]
  • Clinical correlation is required to establish a diagnosis of laryngomalacia.

Treatment

• Reassurance and monitoring in mild cases (approx. 90% of cases resolve by two years of age)
  • Acid suppression therapy (e.,g, PPI, histamine receptor blockers) for patients with symptoms of GERD
  • Speech and swallow therapy
  • Ensure appropriate weight gain
• Supraglottoplasty in severe cases

Definition

• A structural abnormality involving softening or weakening of the tracheal cartilage and/or posterior membrane that results in excessive tracheal collapsibility.
• When the bronchi are also affected, the condition is called “tracheobronchomalacia” (isolated bronchomalacia is extremely rare).

Epidemiology ^[4]

• Most common congenital tracheal abnormality (incidence: approx. 1 in 2100 live births)
• Acquired form is more common than congenital one

Etiology

• Congenital (primary)
  • Idiopathic
  • Cartilage abnormalities (e.g., polychondritis, Ehlers-Danlos syndrome)
  • Underdeveloped respiratory tract (e.g., prematurity, bronchopulmonary dysplasia)
  • Associated with congenital syndromes (e.g., trisomy 21) and/or birth defects (e.g., tracheoesophageal fistula)
• Acquired (secondary)
  • Tracheal trauma (e.g., prolonged intubation, tracheotomy, chest trauma)
  • Airway inflammation (e.g., chronic infections, tracheobronchitis)
  • External compression (e.g., vascular abnormalities, tumors)

Pathophysiology

• Structural weakness of the tracheal cartilage and/or posterior membrane → excessive collapsibility of the trachea during expiration (due to ↑ intrathoracic pressure) → airway obstruction

Clinical features

• Clinical findings differ between infants and adults regardless of the etiology (i.e., congenital or acquired).
• Symptoms may be exacerbated by increased intrathoracic pressure or respiratory effort (e.g., Valsalva maneuvers, forced expiration, crying, coughing) and respiratory infections.
• The intrathoracic trachea is most frequently affected (extrathoracic and cervical tracheomalacia are rare).
• In pediatric patients, symptoms usually appear during the first 2–3 months of age.

Children

• Expiratory stridor
• Barking cough
• Noisy breathing
• Wheezing
• Cyanosis
• Respiratory distress
• Spontaneous hyperextension of the neck

Adults

• Dyspnea
• Cough
• Increased sputum production
• Hemoptysis

Diagnostics

• Diagnostic tests
  • Bronchoscopy (gold standard)
    • Flexible bronchoscopy is preferred
    • Direct visualization of the airway
    • Decrease in airway lumen size and loss of semicircular shape
  • Dynamic airway CT scan: tracheal narrowing
• Additional tests
  • Chest x-ray: may show underlying abnormalities (e.g., structural compression)
  • Pulmonary function tests: obstructive pattern

Treatment

• Asymptomatic or mild tracheomalacia: observation and reassurance
• Symptomatic tracheomalacia
  • Treat underlying causes (e.g., airway inflammation) and coexisting conditions (e.g., COPD)
  • Supportive care (e.g., ipratropium bromide, respiratory physiotherapy)
  • Continuous positive pressure ventilation (if conservative measures fail)
  • Tracheal stenting
  • Surgical repair (e.g., tracheobronchoplasty)

• Subglottic stenosis
• Epiglottitis
• Vocal cord paralysis
• Bronchiolitis
• Asthma
• Cystic fibrosis
• Foreign body aspiration
• GERD

The differential diagnoses listed here are not exhaustive.