External Ear Conditions (Diffuse External Otitis)

What is Diffuse External Otitis?

An infection of the external ear canal is a very common condition. The most common causes include trauma, such as from digging and scratching; swimming (also known as Swimmer's ear); and overuse of antibiotic eardrops. Patients suffering from eczema of the external ear canal are predisposed to infection, usually as a result of hypersensitivity and trauma. The pathogens involved include bacteria such as Pseudomonas aeruginosa and Staphylococcus aureus and fungi such as Aspergillus niger and Candida albicans.

Clinical Features

The patient's main complaints include otalgia (pain), otorrhoea (discharge) and deafness. Acute infections that do not settle within three weeks are then considered to be chronic. When examining the ear, the canal is swollen and filled with debris and discharge (greenish suggests Pseudomonas, creamy suggsts fungal). The tympanic membrane may not be visible but is usually intact although it may be swollen with granulations (granular myringitis).

Investigation

Generally, investigations are not warrented in a simple acute infection. If the condition becomes protracted with little improvement, the discharge should be cultured and sensitivities determined. Rarely is it necessary to biopsy granulation tissue to exclude more sinister conditions.

Management

The key to sucess in managing external ear conditions is regular and meticulous aural toilet. The best method for this is microsuction. If the canal is very swollen, a pope wick is inserted to hasten recovery. Once the ear canal is cleaned, antibacterial or antifungal ear drops should be prescribed, ideally with the addition of a steroid (e.g. Sofradex 5 drops tds for 10 days, or Canesten 5 drops tds for 10 days). Patients should be advised not to swim during the treatment period and to avoid water entering the ear canal during bath time. I recommend using some cotton wool mixed with hand lotion as an earplug during baths. Patients should be reviewed at two-week intervals, and more often for severe infections. Education is also important in preventing future episodes.