Emily Jane is 5 weeks old and her mother Melinda is concerned because she is making a noisy breathing noise.
You note that Emily's breathing is noisier when she lies flat and that it improves when you place her in a more upright position.
When you ask Melinda to describe the noise, she is not sure whether it occurs during inspiration or expiration, but says that it sounds "high pitched".
Emily is feeding well and has normal growth and development. There is no history of choking or breathing difficulties.
History:
Examination:
Definition:
Stridor is a harsh, high-pitched respiratory sound that is usually heard during inspiration. It indicates partial obstruction of the airway, usually at the level of the larynx or trachea.
Common Causes of Stridor in Infants:
| Cause | Key Features |
|---|---|
| Foreign Body | Sudden onset, history of choking, may have unilateral wheeze, variable presentation depending on location |
| Anaphylaxis | Acute onset, associated with exposure to allergen, urticaria, angioedema, respiratory distress, cardiovascular compromise |
| Croup (Laryngotracheobronchitis) | Viral infection, barking cough, fever, preceded by coryzal symptoms, worse at night, age 6 months - 3 years |
| Vocal Cord Paralysis | Present from birth, weak cry, aspiration, may be bilateral or unilateral |
| Laryngomalacia | Most common cause of stridor in infants, present from first few weeks, positional (worse when supine), improves with growth, feeding usually normal |
| Burns/Inhalation Injury | History of fire, smoke exposure, chemical exposure, facial burns, singed nasal hairs |
| Epiglottitis | Rare since Hib vaccination, acute onset, high fever, toxic appearance, drooling, reluctance to lie flat (tripod position), medical emergency |
Other Causes: Subglottic stenosis, laryngeal web, vascular ring, hemangioma, bacterial tracheitis
Red Flags Requiring Urgent Assessment:
Definition:
Laryngomalacia is a congenital softening of the tissues of the larynx (voice box) above the vocal cords. It is the most common cause of stridor in infants.
Pathophysiology:
The exact cause is not fully understood, but involves immature development of the laryngeal cartilage and supporting structures. The supraglottic structures (arytenoid cartilages, aryepiglottic folds, and epiglottis) are abnormally shaped or floppy.
During inspiration, negative pressure causes these floppy structures to collapse inward and partially obstruct the airway, producing the characteristic inspiratory stridor. The "omega-shaped" epiglottis may curl on itself, and the arytenoid cartilages may prolapse anteriorly into the airway.
Clinical Features:
Natural History:
Laryngomalacia is a self-limiting condition in the vast majority of cases. As the infant grows and the laryngeal structures mature and become more rigid, the symptoms gradually improve.
Management:
Conservative (Most Cases):
Indications for Referral to ENT:
Surgical Intervention (Rare - <10% of cases):
Supraglottoplasty may be required in severe cases. This involves surgical division or removal of redundant supraglottic tissue to enlarge the airway opening.
Diagnosis:
Usually clinical. Flexible laryngoscopy can confirm the diagnosis by visualizing the collapse of supraglottic structures during inspiration. This is typically reserved for atypical presentations or severe cases.