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Stridor in infants: laryngomalacia and congenital airway anomalies

The phase of breathing in which stridor is heard reveals the site of obstruction — inspiratory: above the vocal folds; biphasic: at or below the glottis; expiratory: in the trachea and bronchi — and the commonest cause in an infant is laryngomalacia, which resolves on its own in most cases and is operated on only when there are signs of severity.

לקריאה בעברית

Why it matters in the exam

Laryngomalacia causes about 60% of congenital stridor: inspiratory stridor that starts in the first weeks, worsens lying supine, crying and feeding, peaks at age 6 to 8 months and usually resolves by 12 to 24 months. Diagnosis is by flexible laryngoscopy in an awake infant: an omega-shaped epiglottis, short aryepiglottic folds and arytenoid mucosa that collapses inward on inspiration. Reflux is common alongside. Signs of severity — apnoeas, cyanosis, failure to thrive (FTT), severe feeding difficulty and cor pulmonale — justify supraglottoplasty, and in some cases bronchoscopy to look for a second lesion (in about 10% to 20%).

The second commonest cause is vocal fold paralysis: bilateral palsy presents with stridor and a relatively normal voice and is linked to brain malformations (Arnold-Chiari); unilateral palsy presents with a weak cry and aspiration, usually after cardiac surgery. Subglottic haemangioma: biphasic stridor and a "barking" cough appearing at age 1 to 3 months and worsening, sometimes with a skin haemangioma in the "beard" area; treatment is propranolol. An anterior glottic laryngeal web is linked to 22q11 deletion; under Cohen: type 1 — less than 35% obstruction, 2 — 35% to 50%, 3 — 50% to 75%, 4 — 75% to 90%. A laryngeal cleft causes aspiration of feeds and is diagnosed by rigid laryngoscopy with palpation of the interarytenoid area.

Expiratory stridor in an infant points to tracheomalacia or external compression of the trachea (a vascular ring); tracheomalacia is diagnosed by dynamic bronchoscopy during spontaneous breathing. In a child with croup, endoscopy is advised when the course is atypical: age under 6 months, recurrent episodes, a prolonged course or no response to treatment — to exclude stenosis or subglottic haemangioma.

Key points

• Inspiratory — above the folds; biphasic — glottis or subglottis; expiratory — trachea.
• Laryngomalacia: commonest, resolves by 12 to 24 months.
• Severity signs → supraglottoplasty.
• Subglottic haemangioma → propranolol.
• Anterior web → test 22q11.

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Sources

• International Pediatric Otolaryngology Group (IPOG) consensus recommendations: Laryngomalacia, 2016 — Diagnosis, indications for supraglottoplasty
• Cummings Pediatric Otolaryngology, 2nd edition (2021) — Congenital malformations of the larynx; evaluation of the child with stridor
• Nelson Textbook of Pediatrics, 22nd edition (2024) — Congenital anomalies of the larynx, trachea and bronchi

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.