Acute stridor in childhood; retropharyngeal abscess.

Stridor of acute origin (commonly termed croup) is due to laryngeal or tracheal narrowing. The causes can be viral laryngotracheobronchitis (viral croup), acute epiglottitis, laryngeal diphtheria, retropharyngeal abscess, foreign body, allergic oedema, injury by steam or smoke inhalation or intubation and laryngeal spasm due to hypocalcaemia. 1 ,2 The relative importance of the various causes varies with different countries. Diphtheria is extremely rare in the developed countries. Retropharyngeal abscess was common in the pre-antibiotic era. It became less common with the introduction and the widespread use of antibiotics. It is, however, an important cause to recognise. Other than a good clinical examination, a high index of suspicion and a 'good' lateral x-ray film of the extended neck are essential for its diagnosis.