[11] Otitis Externa Flashcards
What is otitis externa?
Inflammation of the outer ear
What does otitis externa include?
Inflammatory conditions of the auricle, external auditory canal and outer surface of the ear drum
How can otitis externa vary?
Can be local or diffuse and acute or chronic
How is the ear canal kept clean?
It is self cleaning and clears itself of debris
How is the ear canal self-cleaning?
Epithelial migration - the skin surface moves laterally from the tympanic membrane towards the ear canal opening
What is ear wax also known as?
Cerumen
What does ear wax consist of?
- Epithelial cells
- Lysozymes
- Oily secretions
What is the role of ear wax?
- Cleaning
- Lubrication
- Protection
- Inhibition of bacterial and fungal growth
- Prevent water from from reaching the canal skin
What can ear wax protect the canal from?
Bacteria, dust and insects
How does ear wax inhibit the growth of bacteria and fungi?
Creates an acidic coat
How does ear wax prevent water from reaching the canal skin?
It has hydrophobic properties
Besides wax, what helps to protect the outer part of the ear canal?
Hair
What is the role of the hair in the outer part of the ear canal?
Prevent objects entering and aid desquamation and skin migration
What is the underlying pathology of otitis externa?
Disturbance of the lipid/acid balance of the ear canal
What is the most common cause of otitis externa?
Infection
What are other potential causes of otitis externa?
- Allergy
- Irritation
- Inflammatory conditions
Bacteria is responsible for what percentage of infective cases of otitis externa?
90%
Fungi is responsible for what percentage of infective cases of otitis externa?
10%
Is bacterial otitis externa usually caused by a single organism?
No, most have multiple organisms involved
What are the most common bacteria involved in otitis externa?
S. aureus and P. aeruginosa
What virus can cause otitis externa?
Herpes zoster
What is an outer ear herpes zoster infection known as?
Ramsay Hunt Syndrome
What causes of skin inflammation can cause otitis externa?
- Seborrhoeic dermatitis
- Acne
- Psoriasis
- Atopic eczema
- SLE
What irritants can cause otitis externa?
- Topical medications
- Hearing aids
- Earplugs
- Ear trauma from foreign bodies
- Water in ear
- Chemicals e.g. hair spray/dye
What are the risk factors for otitis externa?
- Hot and humid climate
- Swimming
- Old age
- Immunocompromised
- DM
- Narrow external auditory meatus
- Obstruction of normal meatus
- Insufficient wax
- Wax build up
- Dermatological conditions
- Trauma to the ear canal
What can cause a narrow external auditory meatus?
- Hereditary
- Chronic infection
What can cause obstruction of a normal external auditory meatus?
- Keratosis obturans
- Foreign body
- Hearing aid
- Hirsute ear canal
What can often lead to insufficient ear wax?
Over-cleaning
Why can wax-build up lead to otitis externa?
Causes obstruction and retention of water, debris and infectious organisms
What dermatological conditions can increase the risk of otitis externa?
- Eczema
- Seborrhoeic dermatitis
- Allergic, atopic or irritant dermatitis affecting the ear canal
What trauma to the ear canal can increase the risk of otitis externa?
- Cotton bud use
- Radiotherapy
What are the main symptoms of otitis externa?
- Pain
- Itching
- Discharge
- Hearing loss
What may be seen on examination in otitis externa?
- Erythem, oedem and exudate in canal
- Mobile tympanic membrane
- Pain on moving tragus or auricle
- Periauricular lymphadenopathy
What are the signs of more severe otitis externa?
- Narrowed and obscured ear canal
- Hearing loss
- Discharge
- Regional lymphadenopathy
- Cellulitis beyond ear
- Fever
When are swabs recommended in otitis externa?
If treatment has failed or the presentation is atypical
Where is the swab in otitis externa best taken from to avoid contamination?
The medial aspect of the ear canal under visualisation
What are the differentials for otitis externa?
- Foreign bodies
- Impacted wax
- Otitis media
- Cholesteatoma
- Referred pain from sphenoid sinus, teeth, neck, or throat
- Barotrauma
- Dermatological disease
What is the aim of treatment in otitis externa?
- Settle symptoms
- Cure infection
- Reduce risk of recurrence
- Prevent complications
What is the most common treatment method for otitis externa?
Topical drops
What other treatment methods can be useful in otitis externa?
Wicking and removal of debris
What should you do if initial treatment of otitis externa fails?
Reconsider diagnosis
When are oral antibiotics indicated in the management of otitis externa?
If there is cellulitis or cervical lymphadenopathy
What do patients with systemic symptoms in otitis externa need?
Same-day ENT review and potentially admission for IV antibiotics
What is chronic otitis externa?
When it is present for > 3 months
How is chronic otitis externa primarily treated?
Identifying the underlying cause and removing it
What should be done if there is no identifiable cause of chronic otitis externa?
7 days of acetic acid 2% drops with corticosteroid drops
If fungal growth is suspected to be the cause of chronic otitis externa what should be prescribed?
Topical antifungal
What are the potential complications of otitis externa?
- Temporary hearing loss
- Acute otitis externa becomes chronic
- Cellulitis
- Necrotising otitis externa
