History
Mohammed is a 3-month-old boy, brought to a paediatric rapid referral clinic because of persistent noisy breathing. He was born in the UK at term after an uneventful pregnancy and is the fifth child of non-consanguineous Somalian parents. His birth weight was 3.7 kg (75th centile). Since he was a few weeks old, he has had noisy breathing, which hasn’t affected his feeding, and his parents were repeatedly reassured that it would get better. He has continued to have intermittent noisy breathing, especially when agitated, and sometimes during sleep. Over the last few days, his breathing has been noisier than usual. Otherwise he has been well without any fevers. All of his siblings have recently had coughs and colds.
Examination
He is active and smiles responsively. Oxygen saturations are 95 per cent in air and his temperature is 36.9ºC. He is coryzal and has intermittent stridor. There is a small ‘strawberry’ haemangioma on his forehead. Respiratory rate is 45/min, there is subcostal recession and mild tracheal tug. Air entry is symmetrical in the chest, with no crackles or wheeze. Cardiovascular examination is unremarkable. His weight is 6.7 kg (75th centile).
Questions
• What is the most likely cause of his stridor?
• What other important diagnoses need to be considered?
• How can the diagnosis be confirmed?
Medicine
Stridor is an inspiratory sound due to narrowing of the upper airway. Mohammed is most likely to have stridor due to laryngomalacia. This means that the laryngeal cartilage is soft and floppy, with an abnormal epiglottis and/or arytenoid cartilages. The larynx collapses and narrows during inspiration (when there is a negative intrathoracic pressure), resulting in inspiratory stridor. It is usually a benign condition with noisy breathing but no major problems with feeding or significant respiratory distress. Most cases resolve spontaneously within a year as the larynx grows and the cartilaginous rings stiffen. The reason Mohammed now has respiratory distress is that he has an intercurrent viral upper respiratory tract infection. A very important diagnosis to consider in this boy is a haemangioma in the upper airway. The majority of haemangiomas are single cutaneous lesions, but they can also occur at other sites and the upper airway is one position where they can enlarge with potentially life-threatening consequences. The presence of one haemangioma increases the likelihood of a second one. This boy should be referred for assessment by an ENT surgeon. There are many other possible congenital causes of stridor which affect the structure or function of the upper airway. Infectious causes of stridor, such as croup and epiglottitis, are very rare in this age group.
Differential diagnosis of stridor in an infant
• Laryngomalacia
• Laryngeal cyst, haemangioma or web
• Laryngeal stenosis
• Vocal cord paralysis
• Vascular ring
• Gastro-oesophageal reflux
• Hypocalcaemia (laryngeal tetany)
• Respiratory papillomatosis
• Subglottic stenosis
The diagnosis of laryngomalacia can be confirmed by visualization of the larynx using flexible laryngoscopy. This can be done by an ENT surgeon as an outpatient procedure. This demonstrates prolapse over the airway of an omega-shaped epiglottis or arytenoid cartilages. Congenital structural abnormalities may also be seen. Lesions below the vocal cords may require bronchoscopy, CT or an MRI scan for diagnosis.
KEY POINTS
• The commonest cause of congenital stridor is laryngomalacia.
• Laryngomalacia can be exacerbated by intercurrent respiratory infections.
need an explanation for this answer? contact us directly to get an explanation for this answer