What is Croup
Croup is a common childhood disease characterized by sudden onset of a distinctive barking cough, inspiratory stridor, hoarse voice, and respiratory distress resulting from upper airway inflammation and edema of the larynx, trachea, and bronchi. 1, 2
Epidemiology and Etiology
- Croup is the most common cause of acute upper airway obstruction in children between 6 months and 6 years of age 1, 3
- The condition typically presents in late fall or early winter 3
- Viral etiology is most common, with parainfluenza viruses (types 1-3) being the predominant cause, though RSV, rhinoviruses, coronaviruses, adenoviruses, influenza, and human metapneumovirus can also cause croup 4
Clinical Presentation
- The classic presentation includes a barking or brassy cough that is often recognizable even before the child is seen 5
- Low-grade fever typically accompanies the respiratory symptoms 1, 2
- Inspiratory stridor develops due to upper airway narrowing 1, 3
- Hoarse voice results from laryngeal inflammation 1, 2
- The condition is often preceded by an upper respiratory infection 3
- Symptoms typically develop suddenly, though viral croup may have a prodrome while spasmodic croup occurs without warning 2
Pathophysiology
- Upper airway inflammation and edema cause obstruction at the level of the larynx, trachea, and bronchi 2
- The narrowing of the subglottic region produces the characteristic stridor and barking cough 1
- Respiratory distress occurs when obstruction becomes significant enough to impair airflow 1, 2
Important Clinical Distinctions
- Diagnosis is made on clinical grounds with no specific confirmatory test required 3
- Radiographic studies are generally unnecessary and should be avoided unless there is concern for an alternative diagnosis 6, 7
- The barking or brassy cough quality, while characteristic of croup, can also occur with tracheomalacia or habit cough 5