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Otitis externa is inflammation of the external ear canal. It may be localised (where there is an infected hair follicle, potentially progressing to a boil in the ear canal) or generalised where there is more widespread inflammation of the skin and subdermis. It can extend to the external ear and the tympanic membrane. It may be acute (< 3 weeks) or chronic (> 3 months). In chronic infection, the lumen of the ear canal progressively narrows and can become completely stenosed over years.
Acute diffuse otitis media may be caused by:
- Bacterial infection (most cases) – most commonly Pseudomonas aeruginosa or Staphylococcus aureus Fungal infection – most commonly Candida albicans or occasionally Aspergillus species in superficial infection or epidermophyton, trichophyton, and microsporum genera in deeper infections
- Seborrheic dermatitis (associated dandruff, eyebrow scaling, blepharitis or facial redness/scaling)
- Contact dermatitis – caused by a local irritant or allergen such as topical medications, hearing aids, or earplugs
- Sometimes no cause is identified
Precipitating factors to otitis externa include:
- Ear trauma – scratching, foreign bodies in ear, cotton buds, ear syringing Excessive moisture – swimming, humid environment
- Chemicals – hair spray, shampoo
- Skin conditions – atopic dermatitis, psoriasis, seborrheic dermatitis
Patients may present with a combination of ear pain, itch, discharge, and hearing loss. The ear canal +/- the external ear may be red, swollen or eczematous with shedding of the scaling skin. There may be discharge present in the ear canal. The eardrum may be inflamed (although this may be difficult to visualise if the ear canal is narrowed or filled with debris). There may be tenderness on moving the ear or jaw.
Patients should be advised to keep the ear dry and to avoid inserting anything into the ear. Simple analgesia can be used. Swabs are required only in treatment failure. Topical ear drops are used (e.g. acetic acid 2% in mild cases or combined corticosteroid and antibiotic in more severe cases). Aural toilet +/- wick insertion may be used if there is extensive swelling and debris which will obstruct topical medication. Oral antibiotics are reserved for patients with severe/resistant infection.