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Otitis Externa

 

Definition of otitis externa

  • Most commonly used to indicate a bacterial infection of the external auditory canal.
  • Technically means inflammation and can be due to various aetiologies.
  • Involvement of the pinna is commonly due to a spreading cellulitis (including the lobule and can spread to facial skin) or perichondritis (cartilaginous infection excluding the lobule).

 

Epidemiology of otitis externa

  • Affects 10% of the population at some time and 1 in 100 people will have it diagnosed per year.
  • More common in swimmers.
  • Be careful in people with diabetes: Increased risk of malignant/necrotizing otitis externa which is osteomyelitis of the skull base.

 

Causes of otitis externa

  • Infection
    • Bacterial (Pseudomonas, Staph aureus)
    • Fungal (aspergillus or candida)
    • Less commonly viral (zoster)
  • Inflammatory skin diseases of any sort
    • Dermatitis (contact or seborrheic); psoriasis; acne
  • Irritants
    • Earplugs, hairspray, hearing aids, swimming-pool water, sweat, ear syringing. These can also precipitate infective otitis externa

 

Features of otitis externa

  • Earache (can be severe)
  • Discharge
  • Make sure to ask about diabetes

 


USMLE-based video on otitis externa

 

Examination in otitis externa

  • Narrowed and inflamed ear canal
  • Debris and discharge in the ear
    • Usually whitish. If hyphae/black think fungal causes
  • Polyp due to recurrent inflammation
  • Necrotising/malignant otitis externa
    • Extension of the infection into the mastoid bone, which gives severe pain and headache, facial nerve palsy (sometimes), failure of treatment and a positive bone scan.
    • Usually caused by pseudomonas

 

Treatment of otitis externa

  • Analgesia
  • Topical eardrops
    • Ciprofloxacin, sofradex, gentisone-HC.
    • Ciprofloxacin if safe if there is a perforation.
  • Aural toilet
    • Either dry mop or microsuction (required secondary care referral)
  • If canal is very narrowed may require a small expanding sponge (‘pope wick’) in the canal to help drops get in.
    • These should be removed after 48 hours.
  • Oral medication alone will not treat it unless there is spread to pinna/face. This requires admission as well as above treatment.
  • Send a swab if no improvement after 1 week.
  • In necrotising otitis externa, pseudomonas is usually the cause, and treatment with several weeks of intravenous antibiotics and topical ear drops is required.

 

Click here to download free teaching notes on Otitis Externa: Otitis externa

Perfect revision for medical students, finals, OSCEs and MRCP PACES

 

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