Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android. Learn more here!

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

Key Features

Essentials of Diagnosis

  • Otalgia

  • Erythema, edema, and purulence of the external auditory canal skin

  • Diabetic or immunocompromised patients are at risk for "malignant" otitis externa (osteomyelitis of the skull base)

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 with associated external auditory canal edema and purulent discharge

  • Erythema and edema of the ear canal skin, often with a purulent exudate, as well as surrounding periauricular cellulitis

  • Manipulation of the auricle elicits pain

  • The lateral surface of the tympanic membrane is often erythematous

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


  • Persistent otorrhea

  • Granulation tissue in the ear canal

  • Deep otalgia

  • In advanced cases, progressive palsies of cranial nerves, such as cranial nerve 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

  • High inflammatory markers, such as erythrocyte sedimentation rate and C-reactive protein, are indicative of malignant otitis externa

Imaging Studies

  • Diagnosis of malignant otitis externa is confirmed by demonstration of osseous erosion on CT scanning in addition to the presence of high inflammatory markers (see Laboratory Tests, above)

  • MRI scanning is often important to rule out abscesses that may result from malignant otitis externa




  • 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), is usually effective

  • Drops should be used abundantly (5 or more drops three or four times a ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.