Otitis Externa

Question 1

Definition

Answer 1

Infection of the external auditory canal

Question 2

Epidemiology

Answer 2

Diabetes
Dermatitis
Trauma
Moisture: swimming, humid environment

Question 3

Risk factors for necrotising otitis externa

Answer 3

Head and neck radiotherapy
Diabetes
Advancing age
Immunosuppression

Question 4

Aetiology

Answer 4

Pseudomonas aeruginosa
Staphylococcus aureus

Fungal causes:
- Aspergillus
- Candida spp

Question 5

Pathophysiology

Answer 5

Distruption of the cerumen barrier with instrumentation (cotton buds, hearing aids, ear plugs) leading to accumulation of moisture and a rise in pH = proliferation of organisms, invasion and inflammation

Question 6

What is necrotising otitis externa?

Answer 6

Invasive form of otitis externa that can lead to osteomyelitis of the temporal bone, multiple cranial nerve palsies and death.

Question 7

Signs

Answer 7

• Otorrhoea
• Erythema
• Fever
• Cranial nerve palsies (NOE)
• Granulation tissue in EAC (NOE)

Question 8

Symptoms

Answer 8

• Pain: ear, jaw, headache (severe in NOE)
• Discharge: canal may be occluded prohibiting otoscopy
• Pruitus
• Hearing loss: conductive, resolves with treatment
• Facial weakness (NOE)

Question 9

Diagnosis

Answer 9

Clinical diagnosis for uncomplicated primary cases in primary care
Recurrent:
- Swab
- Blood glucose: poor BG in a diabetic may exacerbate infection

Question 10

Treatment

Answer 10

Analgesia: paracetamol ibuprofen, codeine
Mild: Topical therapy = acetic acid
Fungal: antibiotic drops with or without topical corticosteroid such as ciprofloxacin 3%/ Dexamethasone 0.1%, Clotrimazole 1% solution if fungal infection suspected.