Otitis Externa Flashcards
Define otitis externa
An inflammation of the skin lining the external canal
What causes otitis externa?
Most often infection - bacterial or fungal
Can by caused by allergies, irritants or inflammatory conditions - seborrhoeic dermatitis or contact dermatitis
What is OE occasionally known as?
Swimmer’s ear
What symptoms are associated with otitis externa?
Pain
Itchy ear
Discharge
Hearing loss - from discharge present in the ear canal
What signs are found on otoscopy?
Ear canal with erythema, oedema, exudate
Pain on moving tragus or auricle
Pre auricular lymphadenopathy
Approximately what percentage of infections are bacterial?
90%
10% are fungal
Most cases of bacterial infection involve what bacteria?
Staphylococcus aureus
Pseudomonas aeruginosa
What usually causes fungal infection?
Aspergillus species
Candida species
What are some risk factors?
Hot and humid climate
Swimming
Older age
Immunocompromised
DM
Narrowed EAM - hereditary or acquired through chronic infection
Insufficient wax - reduced protection
Excessive wax - obstruction, retention of debris
Dermatological conditions - eczema, seborrhoeic dermatitis
Dermatitis affecting canal
Radiotherapy to ear, neck or head
What is malignant otitis externa?
A particularly aggressive infection mainly seen in diabetics or immunocompromised patients where the infection spreads from soft tissue of ear canal into the bone
Pseudomonas aeruginosa is causative in 95%
How does malignant otitis externa typically present?
Chronic ear discharge despite topical treatment
Deep seated severe ear pain
Cranial nerve palsies (mostly CNVII)
How should malignant OE be managed?
Aggressive treatment with IV antibiotics
Plus topical treatment
What’s the mortality rate of malignant OE?
10% despite aggressive treatment
What is the management for OE?
Analgaesia Local heat Topical antibiotic or combined topical antibiotic with a steroid for minimum of 7 days, but if symptoms persist continue until resolve (max 14 days) If canal debris consider removal Ear wick if swollen canal Swab discharge in resistant cases
When should acetic acid be used?
Mild cases
Patients prescribed antibiotic/steroid drops can expect symptoms to last how many days once treatment begun?
6 days
When are oral antibiotics indicated?
Systemically unwell
Pre auricular lymphadenopathy
Evidence of spreading infection beyond canal e.g to pinna, neck or face
DM or immunocompromised
If systemic antibiotics indicated, what is usually used?
Flucloxacillin - infection usually due to S. aureus
Or clarythromycin if penicillin allergic
7 day course
What general advise should be given?
Keep ear dry
Avoid cotton wool to plug discharging ear
When is it considered chronic?
Persists for more than 3 months
If the tympanic membrane is perforated, what antibiotic class is typically not used?
Aminoglycosides - concerns about ototoxicity
What are some differentials?
OM
Perforation
Ramsey Hunt syndrome
Furuncle- infection of hair follicle
What is a furuncle?
Small, localised infection with severe pain in ear and local swelling of canal
If lesion bursts there is sudden pain relief
If the discharge is thick white/grey with spores, what may this indicate?
Fungal infection
What should be done on examination?
Examine ear canal, tympanic membrane, auricle, cervical lymph nodes
Examine surrounding tissue for dermatological conditions
Otitis externa can cause significant canal oedema, preventing topical treatment with antibiotic and steroid drops. What should be done in this case?
Referral to ENT - microsuction and insertion of a pope wick needed - to expand the ear canal
What should be done in cases of non resolving otitis externa with worsening pain?
Urgent ENT referral - suggests malignant (necrotising) OE
What should be done if patient fails to respond to topical antibiotics?
Referral to ENT
