Overview
Otitis externa describes the inflammation of the outer ear. This includes the external ear canal, auricular cartilage, and the tympanic membrane. It can be localised or diffuse. Acute diffuse otitis externa is also known as swimmer’s ear.
Acute otitis externa describes inflammation of <6 weeks duration. Chronic otitis externa is inflammation that has lasted longer than 3 months.
Necrotising (malignant) otitis externa is a potentially life-threatening progressive infection that can cause osteomyelitis of the temporal bone and surrounding structures.
Epidemiology
- Very commonly seen, around 10% of people will experience it at least once in their lifetime
Causes
- Staphylococcus aureus and Pseudomonas aeruginosa are the most common causes of acute otitis externa.
- Fungal infections such as Aspergillus or Candida albicans are the most common causes of chronic otitis externa.
- Ramsay Hunt syndrome
- Seborrhoeic or contact dermatitis
- Water in the ears, particularly in swimmers
- Ear trauma or cotton buds
Risk Factors
- External auditory canal obstructions e.g. foreign bodies
- Hot and humid climates
- Increasing age
- Swimming
- Allergy
- Skin problems e.g. seborrhoeic or contact dermatitis
- Immunodeficiency
- Diabetes mellitus
Presentation
The main presenting complaints are ear pain, itching, and discharge. Features include:
- Acute-onset ear pain
- Tenderness of the tragus and pinna, movement of these is usually painful
- Ear canal redness and swelling
- Discharge from the external auditory canal
- Decreased hearing:
- This is usually due to the blockage of the ear canal by swelling/debris
Differential Diagnoses
Chronic otitis externa
- Signs and symptoms last for 3 months or longer
- Patients usually have no pain
Acute otitis media
- Acute otitis media can co-exist with acute otitis externa
- The tympanic membrane is usually erythematous
- Otoscopy may show limited/absent mobility in acute otitis media
- Ear discharge may be seen if the tympanic membrane ruptures
Investigations
All patients
- None needed, otitis externa is usually a clinical diagnosis
- Swabs can be considered if the presentation is atypical/treatment has failed
Management
Referral
Necrotising (malignant) otitis externa should be suspected if any of the following are present. These patients should urgently be referred to ENT:
- Pain and headaches out of proportion to clinical findings
- Exposed bone in the ear canal
- Facial nerve paralysis
All patients
- 1st-line: topical antibiotic eardrops or combined topical antibiotic and steroid eardrops
- Commonly used antibiotics are: gentamicin or ciprofloxacin
- Commonly used steroids are: prednisolone or betamethasone
- Combined therapies usually involve using aminoglycosides + corticosteroids
- Aminoglycosides are contraindicated if the eardrum has perforated
- Consider debris removal
- If initial therapy fails, reconsider diagnosis and refer to ENT
- If there is cellulitis/cervical lymphadenopathy: offer oral antibiotics
- If there are systemic symptoms: same-day ENT review + IV antibiotics in the hospital
Monitoring
- Otitis externa usually resolves relatively quickly within 3 days and does not need routine follow-up
- Patients with recurrent infections are usually followed up
- Patients who have underlying predisposing systemic diseases are usually followed up
Patient Advice
- Children should:
- Be up to date with their vaccinations
- Stay away from smoky environments
- Not have a dummy after 6 months of age
- All patients should:
- Avoid using cotton buds in the ears
- Use earplugs/swimming hats when swimming
- Avoid getting shampoo in the ears when showering/bathing
- Treat conditions such as eczema around the ears
Complications
- Chronic otitis externa
- Necrotising (malignant) otitis externa
- Temporary hearing loss
- Cellulitis
Prognosis
- Most cases resolve within 3 days of starting treatment
