Otitis externa

Question 1

Definition

Answer 1

Otitis externa = inflammation of the outer ear – auricle, external auditory canal and outer surface of eardrum:

1. Acute diffuse otitis externa – moderate temperature and lymphadenopathy, diffuse swelling, variable pain and pruritus, moving ear/jaw is painful, impaired hearing, bacterial infection common

• Also called Swimmer’s ear

2. Chronic otitis externa – fungal and associated with underlying skin conditions, diabetes, immunosuppression

• Discharge and itch are common
• Less acute

3. Necrotising otitis externa – life-threatening extension into mastoid and temporal bones
   - Mainly due to P. aeruginosa or S. aureus
   - Mainly in elderly
   - Criteria – pain, oedema, exudate, micro abscess, granulation tissue, pseudomonas culture
   - If suspected requires urgent ENT referral

Question 2

Risk factors

Answer 2

• Hot and humid climates
• Swimming
• Older age
• Immunocompromised
• Diabetes
• Wax build-up
• Narrow external canal
• Obstruction of canal
• Insufficient wax (predispose infection)

Question 3

Investigations / Mx

Answer 3

Investigations: Swabs and culture

Management (acute otitis externa):

o Topical drops of…
- Acetic acid but is only effective for 1 week
- Antibiotics – neomycin or clioquinol
- Wicking and removal of debris

o If this fails, reconsider diagnosis

o If cellulitis or cervical lymphadenopathy -> oral antibiotics