Retropharyngeal abscess

Common in children younger than 4 years of age because the retropharyngeal space contains lymph nodes that atrophy after the age of 6, but there is an increasing incidence in adults (different pathophysiology – initial cellulitis of the retropharyngeal space spreads rapidly to form an abscess).

Causes:

pharyngitis / otitis media / parotitis / tonsillitis / Ludwig’s angina

dental infections / dental procedures

extension from vertebral osteomyelitis / discitis

upper airway instrumentation / endoscopy

trauma + foreign bodies (e.g. fish bones)

haematologic spread

Pathogens: usually polymicrobial with a mixture of aerobic bacteria (Beta-hemolytic Streptococcus, Staphylococcus spp., anaerobic bacteria (Bacteroides), Gram-negative bacteria (Haemophillus). Mycobacterium tuberculosis can cause retropharyngeal abscesses as well, but they are “cold” abscesses, that rarely present with fever or systemic features.

Signs / symptoms: fever, drooling, sore throat, dysphagia, odynophagia, neck pain and stiffness, dysphonia (“duck quack” or “cri du canard” voice), stridor, trismus or respiratory distress; tenderness on moving the trachea and larynx sideways (“tracheal rock sign”).

These patients prefer to remain supine (to prevent the oedematous retropharynx from occluding the airway), as opposed to the patients with epiglottitis / severe croup who prefer to sit forward / tripod position.

Complications: airway obstruction, mediastinitis, abscess rupture + aspiration pneumonia, epidural abscess, sepsis, jugular venous thrombosis

Imaging options:

Xray lateral soft tissues neck: prevertebral soft tissue swelling (>1/2 vertebral body width at C2-C4 or > 1 vertebral body width at C6-C7); rarely gas, or air-fluid levels.

CT of the neck with IV contrast or MRI: definite diagnosis + size of abscess + local complications

Treatment: IV antibiotics (same regimen as for peritonsillar abscesses), with or without surgical drainage.

They all need urgent ENT review / management and admission to intensive care unit due to the potential for airway obstruction.