Croup (Laryngotracheobronchitis):
Clinical:
Croup is the result of a viral infection (esp. parainfluenza, but also influenza A or B, or respiratory synctial virus) which causes subglottic tracheal narrowing. Patients are usually between the ages of 3 mo. to 3 yr. The disorder is seasonal with a peak incidence between Oct. to April. Patients usually present with wheezing or a "croupy" (barking) cough. On a soft tissue film of the airway there is "steepling" of the subglottic region on the AP film. Distention of the hypopharynx can also be seen especially on the lateral film.Bacterial tracheitis or membranous croup sometimes follows a viral croup and occurs due to a bacterial infection of the trachea with Staphylococcus aureus, Haemophilus influenza (type B), group A beta-hemolytic Streptococcus, or Diphtheria. Like epiglotitis, membranous croup is a medical emergency with the potential for complete airway obstruction and death. Patients are usually between 1 months and 6 years of age and can present with stridor, dyspnea, and high fever. The infection can be complicated by a pneumonia. On soft tissue airway film there may be irregularity of the tracheal outline and debris within the subglottic airway. When the membrane is detached it can mimick an intratracheal foreign body. The condition may be complicated by or present in association with pneumomediastinum [1].
REFERENCES:
(1) AJR 1998; Hedlund GL, et al. Pneumomediastinum as an early radiographic sign in membranous croup. 170: 55-56 (No abstract available)
