Croup (Viral laryngotracheobronchitis)

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What is Croup?

Croup is a syndrome, which is a collection of symptoms and signs that consists of hoarse voice, harsh barking cough and an inspiratory stridor (a high pitched noice made with inspiration). There are many causes of croup, the most common of which is viral laryngotracheobronchitis. Many other conditions can cause croup, some of these other causes include:

Supraglottic obstruction (obstruction of the airways occurring above the epiglottis)
- Acute enlargement of the tonsils
- Foreign body in the airways
- Retropharyngeal abscess (abscess behind the tissues of the pharynx)
- Epiglottitis (rare)
- Acute angioedema
Laryngeal/ subglottic (obstruction occurring below the epiglottis)
- Viral croup
- Spasmodic croup
- Foreign body
- Bacterial tracheitis (inflammation of the trachea)
- Laryngomalacia +/- viral infection (in infants)
- Diptheria
- Thermal/ chemical injury
- Intubation trauma
- Laryngospasm (spasm of the larynx)
Tracheal
- Foreign body
- Bacterial tracheitis
- Tumour (e.g. anterior mediastinal lymphoma)
- Trauma (e.g. haematoma)
- Congenital abnormality

Who gets Croup?

2% of children develop croup annually and it is a common cause of airway obstruction. Children aged from 6 to 36 months are most commonly affected, with most of those children being between 1 and 2 years of age.

Predisposing Factors

Risk factors for developing croup include the following:

Seasonal variation; with the highest incidence in late autumn, however the condition can occur all year round.
Viral infection; 75% of all cases are the result of infection with parainfluenza virus, most commonly type I. Other causes include respiratory syncytial virus (RSV), metapneumovirus, influenza A and B, adenovirus, and mycoplasma.
Prematurity
Young age
Asthma, specifically for spasmodic croup

Progression

Croup usually begins as a condition that mimics the common cold. In the first 1 to 3 days of the condition patients suffer from a combination of runny nose, sore throat, slight cough as well as a low grade fever. After the initial phase, symptoms that are characteristic of an upper airway obstruction occur, these include the characteristic barking cough, hoarseness as well as an inspiratory stridor. The symptoms of croup can worsen at night, and usually resolve after a week. It is important to note that agitated children can develop life threatening aggravation of symptoms, which is why it is important to keep the child as calm and as happy as possible. As a rule of thumb, older children suffer less severe symptoms than younger children.

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