Acute otitis externa

Question 1

What is acute otitis externa?

Answer 1

• Infective condition w/ inflammation of the skin of the EAC

- Generalised inflammation of EAC (vs localised in furuncle)

Question 2

What are the risk factors for acquiring acute otitis externa?

Answer 2

Systemic

• Skin conditions (e.g. eczema, psoriasis)
• Skin infections (e.g. impetigo)
• Immunocompromised e.g. diabetes

Local

• Trauma (cotton-bud, dirty fingernail)
• Local infection (viral/bacterial/fungal)
• 2° to middle ear suppuration
• Irritation due to constant exposure to water (‘Swimmer’s ear’)

Question 3

What are the pathogens that cause acute otitis externa?

Answer 3

• Bacterial: Pseudomonas (very common), Staph (very common), Strep
• Fungal (otomycosis): Candida albicans (white spores), Aspergillus niger (black spores)
• Viral

Question 4

What are the symptoms of acute otitis externa?

Answer 4

Pain, itch, discharge, +/- CHL (inflam and debris partially/totally occluding EAC)

Question 5

What are the complications of AOE?

Answer 5

Perichondritis (spread to the auricle) -> can result in avascular necrosis (AVN) -> deformity (cauliflower ear)

Facial cellulitis (spread to surrounding tissues)

When pinna inflammation doesn’t affect earlobe 🡪 only cartilage is affected (i.e. perichondritis). If earlobe is involved 🡪 skin is affected (not just cartilage) (i.e. cellulitis). This distinction arises because the earlobe is devoid of cartilage.

Malignant otitis externa (MOE) (in elderly, DM, immunocompromised)

Question 6

What is the management of AOE?

Answer 6

Treatment

• **Regular aural toilet via suction or dry mopping: most impt in reducing pathogen load.
• Bac: Topical Sofradex +/- systemic abx for gross cellulitis, perichondritis, or MOE. KIV oral abx if there is spread (perichondritis, cellulitis) or osteomyelitis (malignant otitis externa MOE)
• Fungal: Topical clotrimazole (Canestan), warn of burning sensation during application
• Adequate analgesia if patient complaints of pain

Prevention – pt education
- KED (keep ears dry) – block ears w cotton balls coated in - Vaseline, avoid all water based activities. Ear plugs not preferred as harder to keep clean
- Do not put object
TCU clinic: after inflam settles, examine TM to exclude middle ear disease as underlying cause

Often self-limiting, but watch closely for elderly, diabetics and immunocompromised for possible development into malignant otitis externa MOE

Question 7

What is a furuncle?

Answer 7

• localised otitis externa
• Infection of hair follicle 2’ obstruction of sebaceous duct (only outer 1/3 of EAC is hair-bearing & cartilaginous)
• Usually occurs when patient digs ear with nails and breaks the skin

Question 8

What is the pathogen that cause a furuncle?

Answer 8

Staph. aureus

Question 9

What are the clinical features of a furuncle?

Answer 9

otalgia, CHL (if obstructing EAC)

Question 10

How is a furuncle managed?

Answer 10

• Topical abx +/- oral (systemic) abx

- KIV drainage + packing the EAC to prevent pus collection

Question 11

What are the risk factors of Malignant otitis externa (MOE)?

Answer 11

elderly, diabetic, immunocompromised

Question 12

What is the pathogen that causes MOE?

Answer 12

Pseudomonas (95%) 🡪 spreads to bone, producing osteomyelitis of skull base

Question 13

What are the symptoms of MOE?

Answer 13

• Severe otalgia (nocturnal, extending into the TMJ -> pain w chewing)
• Otorrhoea (unresponsive to routine topicals for otitis externa)

Otalgia and otorrhoea in an elderly diabetic pt = malignant otitis externa (MOE) until proven otherwis

Question 14

What are the signs of MOE?

Answer 14

• Granulation tissue at inferior portion of EAC (bone-cartilage junction)
• CN palsies: CN 7 and nerves exiting jugular foramen (CN 9, 10, 11)

Question 15

What is the complications of MOE?

Answer 15

• Meningitis
• Brain abscess
• Sigmoid sinus thrombophlebitis

Question 16

How is MOE managed?

Answer 16

• Prompt Tx needed due to risk of mortality! Usually will remove infected bones, but you cannot remove parts of skull – immediate hospitalisation + IV Abx! Do not let it spread to the brain (can lead to death)
• High dose IV piptazo and gentamicin (dual anti-Pseudomonal abx) up to 6 weeks
• +/- surgical debridement