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For further information, see CMDT Part 8-03: Diseases of the Ear Canal

Key Features

Essentials of Diagnosis

  • Painful erythema and edema of the ear canal skin

  • Purulent exudate

  • In diabetic or immunocompromised patient, may evolve into osteomyelitis of the skull base ("malignant external otitis")

General Considerations


  • There is often a history of recent water exposure ("swimmer's ear") or mechanical trauma (eg, scratching, cotton applicators)

  • Otitis externa is usually caused by gram-negative rods (eg, Pseudomonas, Proteus) or fungi (eg, Aspergillus), which grow in the presence of excessive moisture


  • Usually caused by Pseudomonas aeruginosa

  • Osteomyelitis begins in the floor of the ear canal and may extend into the middle fossa floor, the clivus, and even the contralateral skull base

Clinical Findings

Symptoms and Signs


  • Otalgia, frequently accompanied by ear canal pruritus

  • Erythema and edema of the ear canal skin, often with a purulent exudate

  • Manipulation of the auricle often elicits pain

  • Because the lateral surface of the tympanic membrane is ear canal skin, it is often erythematous

  • In contrast to acute otitis media, the tympanic membrane in otitis externa moves normally with pneumatic otoscopy

  • When the canal skin is very edematous, it may be impossible to visualize the tympanic membrane


  • Persistent foul aural discharge

  • Granulations in the ear canal

  • Deep otalgia

  • In advanced cases, progressive palsies of cranial nerves VI, VII, IX, X, XI, or XII

Differential Diagnosis

  • Otitis media

  • Skin cancer

  • Traumatic auricular hematoma

  • Cellulitis

  • Chondritis or perichondritis

  • Relapsing polychondritis

  • Chondrodermatitis nodularis helicis


Laboratory Tests

  • Persistent discharge unresponsive to treatment should be cultured

Imaging Studies

  • Diagnosis of malignant otitis externa is confirmed by demonstration of osseous erosion on CT scanning




  • In cases of swimmer's ear, after getting moisture into the ear, acidification with a drying agent (ie, a 50/50 mixture of isopropyl alcohol/white vinegar) is often helpful

  • When infected, an otic antibiotic solution or suspension of an aminoglycoside (eg, neomycin/polymyxin B) or fluoroquinolone (eg, ciprofloxacin) with or without a corticosteroid (eg, hydrocortisone) are usually effective

  • Drops should be used abundantly (5 or more drops three or four times a day) to penetrate the depths of the canal

  • In recalcitrant cases, particularly when cellulitis of the periauricular tissue has developed, oral fluoroquinolones (eg, ciprofloxacin, 500 mg twice daily orally for 1 week) are the drugs ...

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