Epidemiology

• Acute epiglottitis is most common in children between the ages of 2 and 8, although it can occur at any age
• In adults, presentation may resemble an upper respiratory tract infection.
• Unexplained sore throat and anterior neck tenderness over the hyoid bone suggest epiglottitis.^[1]
• Stridor is a sign of upper airways obstruction and is a surgical emergency.
• Diagnosis in adults can be difficult, as they may not have signs of respiratory distress (stridor). Patients with a significant sore throat with no obvious aetiology should be referred to ENT for direct visualisation of their larynx by flexible laryngoscopy. Lateral X-ray of neck is of limited value. Once diagnosed, these patients should be hospitalised and monitored, as airway obstruction may develop rapidly.^[2]
• Epiglottitis is now rare among children, due to vaccination against Hib.^[3]
• In adults, the three most frequently documented symptoms are sore throat (100%), odynophagia (94%) and inability to swallow secretions (63%). The two most frequently documented signs are swelling of the epiglottis/supraglottis (100%) and tachycardia (53%). Outcomes are generally good with fewer cases needing intubation than among children.^[4]

Aetiology

• Bacterial causes include Haemophilus influenzae type b (Hib) (25% are adult cases, becoming less common since the advent of immunisation), pneumococci, Group A beta-haemolytic streptococci, Pseudomonas spp., Mycobacterium tuberculosis. 
• Viruses include herpes simplex virus.
• Candida spp. and Aspergillus spp. in immunocompromised patients.
• Non-infectious causes of epiglottitis include thermal causes (eg, crack cocaine smoking and marijuana smoking, caustic insults (eg, dishwasher pellets) and foreign bodies.
• Reactive epiglottitis may also occur as a reaction to head and neck chemotherapy.

Presentation

Many of the signs and symptoms associated with acute epiglottitis are common, and may occur in many less serious disorders. Patients with epiglottitis may present with any of the following, and the symptoms may evolve very quickly over a period of a few hours.^[5]

The most common symptoms

• Sore throat.
• Odynophagia (painful swallowing).
• Drooling (inability to swallow secretions).
• Fever.
• Anterior neck tenderness over the hyoid bone.

Other features

• High temperature.
• Tachycardia.
• Ear pain.
• Cervical lymphadenopathy.
• The 'tripod sign' - the patient leans forward on outstretched arms to move inflamed structures forward, thereby easing the upper airway obstruction.^[2]

With more severe epiglottitis

• Dyspnoea.
• Dysphagia.
• Dysphonia.
• Stridor (late finding - indicates airway obstruction).
• Respiratory distress.

Differential diagnosis

The differential diagnosis will depend on the presenting symptoms and age of the patient; however, generally included are:

• Pharyngitis
• Laryngitis
• Inhaled foreign body
• Croup
• Retropharyngeal abscess

Investigations

• Fibre-optic laryngoscopy remains the 'gold standard' for diagnosing epiglottitis, as the epiglottis can be seen directly. Laryngoscopy in these patients should only be performed in areas such as operating theatres which are prepared for intubation or tracheostomy in the event of upper airway obstruction.
• Lateral neck X-ray may be useful if laryngoscopy is not possible. Soft-tissue radiograph of the neck may show the 'thumbprint sign'.^[6]
• Throat swabs may be taken when the airway is secure, or when intubation/tracheostomy facilities are at hand. Streptococci are becoming the major pathogens in acute epiglottitis now.^[7]
• Blood cultures may be taken if the patient is systemically unwell.
• CT or MRI scans may be performed if abscess formation is suspected.

Management

• The incidence of acute epiglottitis is falling in children but rising in adults. Initial presentation may resemble a viral sore throat, so a high index of suspicion is needed. Emergency referral is required if signs of airway obstruction are present (stridor). Deterioration in symptoms may be rapid. Management is usually conservative but intubation is occasionally needed (if >50% airway obstruction occurs).^[8]
• Surgical tracheostomy may be required in patients with severe airway obstruction in whom intubation has not been possible.
• Abscess formation is being increasingly seen as epiglottitis cases in adults increase. Drainage may be required in some patients.

Complications

Epiglottitis, if not adequately treated, may occasionally result in:

• Abscess formation
• Meningitis
• Septicaemia
• Pneumothorax
• Pneumo-mediastinitis (very rare)

Prognosis

The great majority of patients will make a complete recovery with no sequelae if early and appropriate treatment are given. Death may occur rapidly if the condition is not recognised and complete airway obstruction occurs.^[9]

Prevention

Vaccination against Hib has dramatically reduced the incidence of acute epiglottitis in children in those countries in which the vaccination is included in the routine vaccination protocol for children.

Future considerations

It is becoming increasingly obvious that vaccination of children with Hib is resulting in resurgence of Hib-associated infections in older-age patients. This requires further observation and surveillance methods to determine how best to manage this.^[10]