Otitis externa

Question 1

Define otitis externa

Answer 1

Inflammation of the outer ear – auricle, external auditory canal and outer surface of eardrum

Question 2

Aetiology of acute otitis externa

Answer 2

Pseudomonas aeruginosa or S. aureus
AKA swimmer’s ear
< 6 weeks moderate fever, lymphadneopathy, diffuse swelling, pain and pruritus
moving ear/jaw is painful, impaired hearing, bacterial infection common

Question 3

What is chronic and necrotising/malignant otitis externa

Answer 3

Chronic = >3 months, caused by fungi

Necrotising/malignant = life-threatening extension into mastoid and temporal bones → osteomyelitis
- pseudomonas aeruginosa or S. aureus
- Elderly patients
- Pain, oedema, exudate, micro abscess, granulation tissue, pseudomonas on culture
- RF: uncontrolled DM, immunocompromise, radiotherapy to ear/head/neck, previous ear surgery or irrigation

Question 4

Risk factors for otitis externa

Answer 4

Hot and humid cliamtes
Swimming
Older age
Immunocompromised
Wax build up OR insufficient wax
Narrow/obstructed canal
Skin conditions e.g. eczema, psoriasis
Previous otitis media
Trauma to the ear canal/foreign bodies in the ear

Question 5

Symptoms and signs of otitis externa

Answer 5

Rapid-onset (48hrs)
- Itch of ear canal
- Ear pain and tenderness of the tragus and/or pinna
- Jaw/ear pain on movement
- Ear discharge
- Hearing loss (due to ear canal occlusion)

• Tragus and/or pinna tenderness
• Ear canal is red and oedematous
• Debris and ear discharge in the ear canal
• Tympanic membrane erythema
• Cellulitis of the pinna and adjacent skin
• Conductive hearing loss
• Tender regional lymphadenitis

Question 6

Symptoms and signs of chronic otitis externa

Answer 6

Chronic: constant itch in the ear with mild discomfort/pain

lack of ear wax, dry scaly skin, canal stenosis, fluff cotton-like debris, conductive hearing loss

Question 7

Symptoms and signs of necrotising/malignant otitis externa

Answer 7

unremitting disproportionate ear pain/headache/purulent otorrhoea/fever/malaise, vertigo, profound conductive hearing loss

systemically unwell, granulation tissue on the floor of the ear canal, exposed bone in the ear canal, ipsilateral facial nerve palsy, conductive hearing loss

Question 8

Differentials for otitis externa

Answer 8

Otitis media
Foreign body
Impacted ear wax
Contact dermatitis/eczema/fungal skin infection
Choleastoma
Ramsay-Hunt syndrome

Question 9

Management for otitis externa

Answer 9

Topical drops/spray of:
- Acetic acid 2% drops (but is only effective for 1 week)
- Antibiotics – neomycin or clioquinol 2-3 drops BD for 7-10 days
- Prednisolone 2-3 drops every 2-3 hours (chronic OE)
Clean the external auditory canal (aural toilet): dry swabbing, ear irrigation
Wicking and removal of debris
If this fails, reconsider diagnosis
If cellulitis or cervical lymphadenopathy/immunocompromise → oral antibiotics e.g. ciprofloxacin

Malignant otitis externa → URGENT referral to ENT

Self-care
- Avoid damage
- Do not use cotton buds or other objects to clear the ear canal
- Keep clean and dry: avoid swimming and water sports (7-10days), caps when swimming, keep shampoo soap and water out of the ear when bathing, consider using a hair dryer to dry the ear after contact with water
- Use analgesia e.g. paracetamol or ibuprofen

Question 10

Complications of otitis externa

Answer 10

Chronic otitis externa
Regional spread of infection → cellulitis, perichondritis, chondritis of pinna, abscess, parotitis
- Erythema and swelling affecting the pinna but sparing the ear lobe = perichondritis
- Erythema and swelling of the ear lobe = pinna cellulitis
Fibrosis and stenosis of the ear canal
Myringitis (tympanic membrane inflammation) → perforation
Malignant otitis externa → facial nerve palsy

Question 11

Prognosis for otitis externa

Answer 11

Acute diffuse otitis externa.
- Symptoms of acute otitis externa usually improve within 48–72 hours of initiation of treatment.
- Between 65–90% of people with uncomplicated diffuse otitis externa have clinical resolution within 7–10 days, regardless of the topical drug treatment used.
Chronic otitis externa.
- The lumen of the ear canal may progressively narrow, and after several years, may become completely stenosed, resulting in hearing loss in the affected ear.
Malignant otitis externa.
- This can be life-threatening. Temporal bone osteomyelitis is associated with a mortality rate of 10–21%.