Otitis Externa

“Infection of the external auditory meatus (a.k.a. swimmer’s ear)”

Risk Factors

• Frequent water contact (e.g. swimming)
• Immunocompromised / diabetes (also increased risk of complications)
• Humid environment
• Local trauma (e.g. cotton bud use, hearing aids)
• Presence of ear polyps, psoriasis or eczema

Aetiology

• Most commonly bacteria (pseudomonas, s. aureus)
• Rarely fungi (aspergillus, candida)

Pathophysiology

• Disruption of the protective mechanisms of the external auditory canal (EAC) may lead to pathogen overgrowth and subsequent inflammation.
• Disruption may be caused by:
  • Interruption in wax formation (e.g. repeated water exposure)
  • Trauma to the EAC (e.g. cotton bud use)
  • Blockage of the EAC (e.g. debris)
• This causes swelling, otorrhoea and debris accumulation, which contribute to further entrapment of pathogens and propagation of the inflammatory response.

Clinical Presentation

• Typically presents as progressive unilateral otalgia with purulent otorrhoea
• Patients commonly experience itchiness or a sensation of ear fullness
• Less common symptoms include tinnitus, hearing loss and swelling
• Exam may show swelling and erythema of the EAC, tragal tenderness, otorrhoea

Investigations

• Diagnosis is based on clinical presentation, however, ear swabs should be considered in recurrent, chronic or non-resolving cases to identify the causative organism

Management

• OTC analgesia (paracetamol, ibuprofen)
• Removal of debris from the external auditory canal
• Topical ear drops (e.g. Otomize: neomycin + dexamethasone + acetic acid)
• Avoidance of contributing factors (e.g. swimming

Complications

• Malignant otitis externa: (infection invades bone at the skull base, causing osteomyelitis)