An inflammatory condition of the ear canal, commonly known as swimmer's ear, characterised by redness, swelling, and pain of the outer ear.
Pathophysiology
- Cerumen (earwax) is important for protection of the ear. It maintains moisture of the ear and acts as a physical barrier against microorganisms and debris.
- It also maintains the pH of the ear canal, specifically maintaining an acidic environment to act as an unfavourable environment for bacterial growth.
- Either the blockage of the ear canal, a disruption to cerumen regulation (e.g. excessive cerumen removal/water exposure), or microtraumas through the means of cotton buds or fingers can result in a bacterial overgrowth, or bacteria breaching the skin barrier, resulting in otitis externa.
Risk Factors
- Swimmers or frequent water contact
- Humidity
- Immunocompromised patients (HIV, diabetes)
- Excessive use of cotton buds
- Eczema/psoriasis involving the ear
Causes
- Bacteria
- Pseudomonas aeruginosa: Gram-negative
- Staphylococcus aureus: Gram-positive
- Fungi e.g. Aspergillus niger or Candida albicans
Clinical Features
- Itching
- Otalgia and discomfort, particularly of the pinna/tragus
- Discharge
- Conductive hearing loss if the ear becomes occluded from debris.
- Erythema/oedema
- Regional lymphadenopathy/lymphadenitis
Management
Conservative
- Avoid using cotton buds or inserting foreign bodies into the ear to remove ear wax.
- Keep the ears clean and dry i.e. no swimming for 7-10 days, keep ears out of water in the shower (applying petroleum jelly to a small ball of cotton wool and placing it over the external meatus to prevent water entering is a good trick).
Medical
- Acetic acid 2% drops/spray: This can be used for maximum 7 days. Works by reducing the pH of the ear canal which helps inhibit bacterial and fungal growth.
- Topical antibiotics +/- topical steroid: Usually 1-2 weeks of gentamicin or ciprofloxacin drops. Steroids are usually used if there is a lot of erythema/oedema/inflammation of the ear canal.
- If patients have a perforated tympanic membrane, aminoglycoside drops i.e. gentamicin drops should not be used as they can be ototoxic.
- Oral antibiotics: Used for patients who are immunocompromised or for severe infections, particularly those which have spread beyond the ear canal.
- Analgesia: Paracetamol/ibuprofen.
- Pope Otowick: These are tiny sponges which can be inserted deeper into the ear canal. They’re usually used when the ear canal is highly oedematous and stenosed, thus making it hard to place drops. They expand when they come into contact with fluid, and can allow drops to penetrate deeper into the canal.
Necrotising Otitis Externa
- This is a progression of otitis externa whereby you have an osteomyelitis of the temporal/mastoid bone.
- It usually occurs in the presence of risk factors such as immunocompromised individuals or diabetic patients. Pseudomonas is the most common offending organism.
- Clinical features include:
- Severe ear pain
- Headaches
- Granulation tissue, usually seen at the bone-cartilage junction of the ear canal.
- Facial nerve palsy
- Dysphagia
- Will require treatment with (usually) IV antibiotics. Diabetes control is also important.
Chronic Otitis Externa
- Otitis externa for >3 months (this is different to recurrent otitis externa, whereby you would expect to have periods of remission between acute episodes of otitis externa).
- The same conservative measures apply as for acute episodes.
- May be caused by a fungal pathogen in which case an anti-fungal needs to be applied e.g. clioquinol and corticosteroid combination drops.
References
https://www.ncbi.nlm.nih.gov/books/NBK556055/
https://cks.nice.org.uk/topics/otitis-externa/
https://www.ncbi.nlm.nih.gov/books/NBK556138/
https://www.aafp.org/pubs/afp/issues/2003/0715/p309.html
