Most Common Cause of Stridor in Children
The answer depends critically on the age of the child: laryngomalacia is the most common cause of stridor in infants, while croup (laryngotracheobronchitis) is the most common cause of acute stridor across all pediatric age groups. 1, 2, 3
Age-Based Etiology
Infants (Birth to 12 Months)
- Laryngomalacia accounts for the overwhelming majority of chronic stridor cases in infants, representing the most common congenital laryngeal anomaly and the most frequent cause of persistent stridor in this age group 1, 2, 4
- In one large series of 202 infants presenting with stridor, 84% had congenital anomalies as the cause, with laryngomalacia representing 94% of all congenital laryngeal anomalies 5
- Laryngomalacia is characterized by collapse of supraglottic structures (epiglottis, aryepiglottic folds, arytenoid cartilages) during inspiration due to diminished laryngeal tone 2, 6
- The condition typically presents in the first 1-2 months of life with inspiratory stridor that worsens with feeding and is positional 7
All Pediatric Ages (Acute Presentation)
- Croup is the most common cause of acute stridor in children presenting with sudden onset of respiratory symptoms 3, 7
- Croup typically presents with the classic triad of barking cough, inspiratory or biphasic stridor, and hoarse voice, usually without preceding fever or respiratory symptoms 3
- The median age of presentation for croup is 23 months, with 63% being male patients 3
Clinical Differentiation
Key Distinguishing Features
- Timing of onset separates these entities: laryngomalacia presents as chronic stridor from early infancy, while croup presents acutely with sudden symptom onset 1, 3, 7
- Associated symptoms differ: laryngomalacia causes positional stridor that worsens with feeding, while croup presents with barking cough and hoarse voice 3, 7
- Stridor characteristics: laryngomalacia typically causes inspiratory stridor only, while croup can cause inspiratory or biphasic stridor 1, 7
Important Clinical Pitfalls
Concomitant Abnormalities
- Up to 68% of infants with stridor have concomitant abnormalities below the epiglottis, making complete airway evaluation essential in persistent or severe cases 1, 4
- In one series, 21% of infants with stridor had at least one other anomaly contributing to airway compromise 5
- Therefore, flexible bronchoscopy should be performed in any infant with severe or persistent stridor, associated hoarseness, oxygen desaturation, or apnea to evaluate both upper and lower airways 1, 3
Misdiagnosis Risk
- Among infants referred with presumptive diagnoses by non-otolaryngologists, 30% had erroneous diagnoses for which they were being treated, with tracheomalacia being the most common incorrect diagnosis 5
- Endoscopy under general anesthesia remains the gold standard for definitive diagnosis when clinical assessment is insufficient 8
Other Important Causes to Consider
- Vocal cord paralysis is the third most common congenital laryngeal anomaly causing stridor in infants 1, 4
- Subglottic stenosis occurs in 1.7-8% of previously intubated neonates and presents with postextubation stridor, hoarseness, or failure to tolerate extubation 9
- Foreign body aspiration must always be considered in acute stridor, particularly with sudden onset and atypical presentation 3, 4
Answer to Multiple Choice Question
For the general pediatric population: b. Laryngomalacia is the correct answer when considering all causes of stridor in children, as it represents the most common congenital cause and the most frequent etiology of chronic stridor in infants who comprise the majority of children presenting with stridor (87% were ≤6 months in one series) 5, 6, 10
However, if the question specifically refers to acute stridor: a. Croup would be the correct answer, as it is the most common cause of acute stridor across all pediatric ages 3, 7