Stridor and Laryngomalacia
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Direct answer
Stridor is a high-pitched noise produced by turbulent airflow through an obstructed upper airway, and laryngomalacia is the commonest cause of persistent stridor in infants. Laryngomalacia is a congenital softening of the supraglottic structures, which collapse inward during inspiration. It usually presents in the first weeks of life and improves by 18 to 24 months, so management is largely reassurance and monitoring for feeding problems and severe airway obstruction.
What you must remember
- Inspiratory stridor: suggests extrathoracic obstruction above the thoracic inlet, such as at the larynx or supraglottis.
- Expiratory stridor: suggests intrathoracic obstruction in the trachea or bronchi.
- Biphasic stridor: suggests a fixed lesion at the glottis or subglottis.
- Laryngomalacia: the commonest congenital laryngeal anomaly, with stridor that is worse when supine, feeding or crying.
- Diagnosis: flexible laryngoscopy is the investigation of choice, showing supraglottic collapse and excluding other lesions.
- Infants: vascular ring, subglottic stenosis, vocal cord palsy and subglottic haemangioma must be considered when the stridor is atypical or feeding fails.
- Children: croup, epiglottitis, foreign body aspiration and retropharyngeal abscess are the important causes beyond infancy.
Approach to a stridulous infant
A 5-week-old has noisy inspiratory breathing that worsens with feeding and crying, with normal oxygen saturation. The approach first separates an airway emergency from a benign, self-limiting cause.
- Assess for an airway emergency. Look for severe recession, cyanosis, drooling, agitation or exhaustion, since any of these needs immediate airway support.
- Avoid distressing the child. Do not examine the throat or take a swab when epiglottitis is possible, because crying can cause complete obstruction.
- Take a focused history. Ask about the onset, feeding difficulty, choking episodes, cough and fever, and whether the noise is worse when supine or feeding.
- Describe the pattern. Note whether the stridor is inspiratory, expiratory or biphasic, and check for failure to thrive, dysphagia or a hoarse cry.
- Investigate with endoscopy. Flexible laryngoscopy is the investigation for persistent stridor, showing supraglottic collapse in laryngomalacia or the lesion in other causes.
- Reassure or treat. Mild laryngomalacia needs reassurance and monitoring of weight gain, whereas severe cases with feeding failure or cyanosis may need supraglottoplasty.
Where the exam tries to catch you
The exam tests the link between the pattern of stridor and the level of obstruction.
- Trap: calling all infant stridor laryngomalacia Correct: vascular ring, subglottic stenosis and vocal fold palsy must be excluded, particularly when feeding fails or cyanosis appears.
- Trap: examining the throat of a child with suspected epiglottitis Correct: throat examination can precipitate complete obstruction, so the child is kept calm and managed by the airway team.
- Trap: treating laryngomalacia like croup with steroids Correct: steroids have no role in laryngomalacia, which is managed by reassurance, whereas croup is a separate diagnosis.
Frequently asked questions
Why does laryngomalacia cause inspiratory stridor?
Laryngomalacia causes inspiratory stridor because the immature supraglottic structures, including the arytenoids and epiglottis, collapse inward when the infant breathes in. The stridor is worse when supine, feeding or crying, and it usually improves as the supraglottic cartilage matures by 18 to 24 months.
Which investigation confirms laryngomalacia in an infant with stridor?
Flexible laryngoscopy confirms laryngomalacia in an infant with stridor, by showing inward collapse of the supraglottic structures during inspiration. It also excludes other causes such as vocal fold palsy and subglottic lesions, and it is often done with the infant awake.
How do croup and epiglottitis differ in children with stridor?
Croup is a viral laryngotracheobronchitis that causes a barking cough and subglottic narrowing, and it responds to steroids. Epiglottitis is a rapid, often bacterial inflammation of the epiglottis that causes drooling and a toxic child, and it is an airway emergency requiring specialist care.
Which children with stridor need urgent airway assessment?
Children with stridor and severe recession, cyanosis, drooling, agitation or exhaustion need urgent airway assessment. Foreign body aspiration, epiglottitis and retropharyngeal abscess are the causes most likely to deteriorate quickly.