Otitis Externa

Definition/diagnostic criteria Otitis externa is an inflammation of the external auditory canal, the auricle, or both. It ranges from acute, simple cases to chronic or severe infections that may necessitate systemic treatment. It is diagnosed based on the presence of ear itch, ear pain (otalgia), discharge (otorrhea), ear fullness, and occasionally hearing loss, with symptoms lasting less than six weeks for acute cases and more than three months for chronic cases (NICE CKS, 2020).

Epidemiology Otitis externa affects 1% to 2% of the UK population annually and accounts for about 1 in 250 general practice consultations. It can occur at any age but is most prevalent in swimmers and individuals between 45 and 75 years of age. It is more common in humid conditions and during the summer months.

Diagnosis

Clinical features

The diagnosis is primarily clinical, characterized by a rapid onset of ear pain, itching, or discomfort, often with partial hearing loss or a sensation of ear blockage and possible discharge. Examination may reveal erythema, swelling, scaling, discharge and debris in the ear canal. Manipulation of the auricle or tragus elicits pain, and there might be regional lymphadenopathy.

Investigations

Typical investigations include otoscopy, revealing erythema, oedema, and narrowing of the external auditory canal. Specific tests, such as swab cultures, are not routinely recommended but can be considered in severe, refractory, or recurrent cases to guide antibiotic therapy..

Treatment Treatment aims to relieve symptoms, eradicate infection, and prevent recurrence. Initial management involves cleaning the ear canal, followed by topical treatments. Usual treatment is a combination of topical antibiotics and corticosteroids for mild to moderate cases (e.g. neomycin with hydrocortisone). Analgesics are advised for pain management. For cases unresponsive to initial treatment, culture-directed systemic antibiotics may be necessary. Fungal infection many require topical antifungals. Patients are also advised to keep the ear dry (avoid swimming or water sports) and avoid inserting objects into the ear.

Prognosis Most cases of acute otitis externa resolve within 7-10 days with appropriate treatment. However, chronic otitis externa can persist for months or even years and may require ongoing management. Complications are rare but can include cellulitis, abscess formation, and necrotizing (malignant) otitis externa, especially in immunocompromised patients or those with diabetes.

Malignant otitis externa is a severe, potentially life-threatening infection that extends into the skull base. It predominantly affects elderly diabetic patients and is characterized by severe otalgia, otorrhea, and cranial nerve palsies. Prompt diagnosis and aggressive treatment with systemic antibiotics and possibly surgery are crucial for a favourable outcome.

ENT UK.