Acute subglottic laryngitis (ASL) is an inflammatory condition of the larynx, which causes narrowing of the latter. It predominantly occurs in children and presents with difficulty in breathing, voice changes, and a barking cough.
Acute subglottic laryngitis (ASL), sometimes called pseudo-croup, is an infection that is usually seen in children and has a higher prevalence in boys. Most cases are reported at around one and a half years of age. In some literature, infection is only considered to be ASL if the causative organism is a virus . ASL can, however, be bacterial or fungal. Furthermore, other sources of literature distinguish pseudo-croup from croup based on the causative organism, with croup being caused by the Corynebacterium diphtheriae.
The most frequently implicated virus is the parainfluenza virus. Initial viral infection can be followed by bacterial superinfection  . The rate of occurrence of ASL may be higher in certain seasons, namely autumn and winter . There are several modes of infection, for example, through airborne organisms, blood or trauma . Some cases of ASL are preceded by other respiratory tract infections. Precipitating factors of ASL include infections, both local and systemic, hypersensitivity reactions, air pollution, cigarette smoke, and foreign bodies.
Symptoms are mainly due to the primary characteristic of ASL, which is narrowing of the trachea in the subglottic region due to inflammation resulting in edema. The extent to which the trachea narrows determines the severity of symptoms. Narrowing of the trachea is made more likely if there is a history of asthma, gastroesophageal reflux disease (GERD), trauma, or preexisting scarring or stenosis . The onset of ASL is rapid and often occurs at night. It is also acute and self-limiting; thus treatment given is supportive.
Respiratory manifestations of the condition include dyspnea, cough, stridor, and hoarseness. Constitutional symptoms may be present, such as fever, cervical lymphadenopathy, loss of appetite, weakness, and restlessness. Cyanosis may also occur due to lack of oxygen. In a few cases, the condition may be life-threatening.
The diagnosis of acute subglottic laryngitis is made via a clinical examination, taking into account both history and physical examination. Laboratory studies are not routinely carried out. If there is pus, this can be cultured, and sensitivity determined before antibiotics are administered . Nose and throat swabs may also be taken. A complete blood count (CBC) may be requested if the infection is thought to be bacterial in origin. Other possible laboratory tests are PCR (polymerase chain reaction), lateral flow tests, and immunoprecipitation.
Imaging modalities include laryngoscopy, although this is not mandatory. Laryngoscopy allows visualization of the inflamed airways and may reveal distortion in the symmetry and movement of the same . Laryngoscopy is often done by a specialist. General practitioners may use indirect laryngoscopy. An additional imaging method is videostroboscopy . This is used when presenting symptoms and laryngoscopic results are mismatched .