Introduction

Otitis externa describes inflammation of the ear canal, usually secondary to infection.

Epidemiology

  • Incidence: 500.00 cases per 100,000 person-years
  • Peak incidence: 40-50 years
  • Sex ratio: 1:1
Condition Relative
incidence
Otitis externa1
Acute otitis media0.50
Cholesteatoma0.02
Mastoiditis0.01
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Pathophysiology

Causes of otitis externa include:
  • infection: bacterial (Staphylococcus aureus, Pseudomonas aeruginosa) or fungal
  • seborrhoeic dermatitis
  • contact dermatitis (allergic and irritant)

Clinical features

Features

Otoscopy findings:
  • view may be limited secondary to discharge, debris or swelling
  • red, swollen, or eczematous canal

Management

The recommended initial management of otitis externa is:
  • topical antibiotic or a combined topical antibiotic with a steroid
  • if the tympanic membrane is perforated aminoglycosides are traditionally not used*
  • if there is canal debris then consider removal
  • if the canal is extensively swollen then an ear wick is sometimes inserted

Second-line options include
  • consider contact dermatitis secondary to neomycin
  • oral antibiotics (flucloxacillin) if the infection is spreading
  • taking a swab inside the ear canal
  • empirical use of an antifungal agent

*many ENT doctors disagree with this and feel that concerns about ototoxicity are unfounded

Complications

Malignant otitis externa is more common in elderly diabetics. In this condition, there is extension of infection into the bony ear canal and the soft tissues deep to the bony canal. Intravenous antibiotics may be required.