Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content + Print Section ++ For further information, see CMDT Part 8-03: Diseases of the Ear Canal + Key Features Print Section ++ ++ 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 ++ EXTERNAL OTITIS ++ 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 ++ MALIGNANT EXTERNAL OTITIS ++ 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 Print Section ++ ++ Symptoms and Signs ++ EXTERNAL OTITIS ++ 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 ++ MALIGNANT EXTERNAL OTITIS ++ 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 + Diagnosis Print Section ++ ++ 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 + Treatment Print Section ++ ++ Medications ++ EXTERNAL OTITIS ++ 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 of choice because of their effectiveness against Pseudomonas species ++ MALIGNANT EXTERNAL OTITIS ++ Prolonged antipseudomonal antibiotic administration, often for several months Although intravenous therapy is often required initially (eg, ciprofloxacin 200–400 mg every 12 hours), selected patients may be graduated to oral ciprofloxacin (500–1000 mg twice daily) ++ Surgery ++ Surgical débridement of infected bone is reserved for cases of malignant external otitis that have worsened despite medical therapy ++ Therapeutic Procedures ++ Fundamental to the treatment of external otitis is protection of the ear from additional moisture and avoidance of further mechanical injury by scratching Purulent debris filling the ear canal should be gently removed to permit entry of the topical medication When substantial edema of the canal wall prevents entry of drops into the ear canal, a wick is placed to facilitate entry of the medication + Outcome Print Section ++ ++ Follow-Up ++ MALIGNANT EXTERNAL OTITIS ++ To avoid relapse, antibiotic therapy should be continued, even in the asymptomatic patient, until gallium scanning indicates a marked reduction or resolution of the inflammation ++ When to Refer ++ Any case of persistent otitis externa in an immunocompromised or diabetic individual must be referred for evaluation by otolaryngology and infectious disease specialists + References Print Section ++ + +Chawdhary G et al. Current management of necrotising otitis externa in the UK: survey of 221 UK otolaryngologists. Acta Otolaryngol. 2017 Aug;137(8):818–22. [PubMed: 28301961] + +Peled C et al. Necrotizing otitis externa-analysis of 83 cases: clinical findings and course of disease. Otol Neurotol. 2019 Jan;40(1):56–62. [PubMed: 30239427] + +Wang X et al. Use of systemic antibiotics for acute otitis externa: impact of a clinical practice guideline. Otol Neurotol. 2018 Oct;39(9):1088–94. [PubMed: 30124617]