Otitis Externa

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Introduction

Otitis externa is the inflammation of the external ear which may result from a variety of insults to the external ear.

May be classified as localized or diffuse otitis externa; or acute or chronic otitis externa

AetiologyMay be:

  • Infective: bacteria or fungi
    • Localized otitis externa or furuncle (boil) is a Staphylococcal infection of a hair follicle in the canal
    • Diffuse otitis externa may be bacterial or fungal or reactive
    • Bacterial infection often follows trauma from scratching the canal skin.
    • Fungal otitis (otomycosis) commonly follows swimming in the tropics, usually infection by Aspergillus niger
  • Reaction of the canal skin to chemical irritant(s)
  • Part of a generalized dermatitis

Clinical features

  • Pain and itching
  • Ear discharge
  • Sensation of blockage due to accumulated debris in canal
  • Deafness is variable
  • Canal is red and swollen, full of inflammatory debris
  • In otomycosis whitish mass of debris with black spots

Differential diagnoses

  • Otitis media
  • Acute mastoiditis

Complications

  • Acute perichondritis

Investigations

  • Ear swab, taken properly for microscopy, culture and sensitivity
  • Ear endoscopy
  • Urinalysis for glycosuria
  • Blood glucose estimation in cases of recurrent furunculosis to exclude diabetes mellitus

Treatment goals

  • Control infection/inflammation
  • Relieve discomfort

Non-drug treatment

  • Careful ear toilet to clear out debris
  • Daily dressing with antiseptic gauze packed with Acriflavin in spirit
  • Furunculosis: dressing with magnesium sulfate wick or steroid and antibiotic ointment dressing

Drug treatment

  • Antibiotics
    • Amoxicillin
      • Adult: 500 mg - 1 g orally every 8 hours for 5 - 7 days
      • Child: 40 mg/kg orally in every 8 hours for 5 - 7 days
    • Neomycin/hydrocortisone ear drops
      • Adult and child: 2 - 3 drops 3 - 4 times daily
  • Analgesics
    • Paracetamol
    • Adult:500 mg -1 g orally every 4 - 6 hours (maximum of 4 g daily) for 5-7 days
    • Child
      • over 50 kg: same as adult dosing
      • 6 - 12 years: 250 - 500 mg 4 - 6 hourly
      • 3 months - 5 years: 125 – 250 mg taken orally every 4 - 6 hours

Supportive measures

  • Prevent water from entering ear for one month

Prevention

  • Avoid trauma to ear canal (especially scratching)
  • Keep ears dry