Otitis Externa

Basics

Description

  • Inflammation or infection of the auricle, auditory canal, or external surface of the tympanic membrane (TM):
    • Spares the middle ear
    • Affects 4/1000 persons in the US
  • Also called “swimmer’s ear” due to the usual history of recent swimming:
    • Occasional cases after normal bathing
  • Necrotizing (malignant) otitis externa:
    • Infection starts at the ear canal and progresses through periauricular tissue toward the base of the skull
    • Occurs in elderly, diabetic, or other immunocompromised patients (chemo, steroids)
    • Caused by Pseudomonas aeruginosa
    • Can lead to cellulitis, chondritis, and osteomyelitis
    • Associated with 20% mortality (50% if untreated)
  • Chronic otitis externa:
    • Common
    • Caused by overmanipulation
    • Incomplete treatment of OE

Etiology

  • Often precipitated by an abrasion of the ear canal or maceration of the skin from prolonged water exposure or excessive dryness
  • Predisposing factors include:
    • History of ear surgery or TM perforation
    • Narrow or abnormal canal
    • Humidity
    • Allergy
    • Eczema
    • Trauma
    • Abnormal cerumen production
  • Most common bacteria:
    • P. aeruginosa
    • Staphylococcus aureus
    • Streptococcal species
    • Otomycosis secondary to fungus species such as Candida or Aspergillus

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