- Clinical science
Otitis externa (OE) refers to inflammation of the external auditory canal, which is most often the result of a local bacterial infection. Risk factors for OE include injury to the skin of the external auditory canal and/or exposure to water. OE is characterized by ear pain, discharge, and tragal tenderness. Otoscopy may reveal a furuncle (localized OE) or a red, edematous external auditory canal (diffuse OE). OE is primarily a clinical diagnosis. Treatment involves keeping the external auditory canal dry and administering fluoroquinolone and hydrocortisone ear drops. Systemic antibiotic therapy is usually indicated in immunosuppressed and/or diabetic patients who are at risk of a more severe variant called malignant otitis externa (MOE). MOE, which is almost always caused by Pseudomonas aeruginosa, may present with facial nerve palsy and is potentially fatal because it spreads rapidly to the base of the skull. Immediate referral and treatment with systemic antipseudomonal antibiotics are indicated.
- Most cases of otitis externa are infectious in origin.
- Bacterial infections (most common cause of otitis externa)
- Fungal infections (less common): Aspergillus (accounts for 90% of all fungal otitis externa), Candida
- Viral infections (rare): Herpes zoster, Influenza viruses
- Injury to the skin of the external auditory canal (e.g., cleaning, insertion of foreign objects such as hearing aids or earplugs, excessive itching)
- Increased moisture in the external auditory canal (e.g., swimming, humid climate)
- Non-infectious forms of otitis externa are less common and include seborrheic otitis externa (which is associated with seborrheic otitis externa), eczematous otitis externa (a hypersensitivity reaction to pathogens or topical antibiotics), and neurodermatitis (caused by compulsive/psychogenic scratching).
- Severe ear pain, particularly at night
- Intense itching in the external auditory canal
- Definition: necrotizing inflammation of the external auditory canal
- Clinical features
- Prompt IV antibiotic therapy for several weeks
- Surgical debridement is indicated for abscess drainage and removal of bony sequestrum
- Topical antibiotic treatment (see “Therapy” below)
- Prognosis: The mortality rate is high even with appropriate antibiotic therapy
Malignant otitis externa is a severe infection that is often lethal!
- Otitis externa is primarily a clinical diagnosis.
- Check blood glucose levels to rule out diabetes
- Culture and sensitivity tests are not routinely performed; they may be indicated if antibiotic treatment is not effective.
- Topical treatment
- Systemic treatment: oral ciprofloxacin
- NSAIDs for pain relief