Croup syndrome.

Spasmodic croup has a sudden onset, almost always at night, and usually responds well to humidification. Laryngotracheobronchitis is the most common form of the croup syndrome; children with this disease generally do well, although some require hospitalization and intubation. Bacterial tracheitis may mimic severe laryngotracheobronchitis; diagnosis is usually established during visualization of the airway. Epiglottitis is rare but is often life-threatening.