External Otitis

(Swimmer's Ear)

External otitis is infection of the external auditory canal, usually by bacteria. Typical symptoms include itching, pain, and discharge. Diagnosis is based on physical examination. Treatment is with topical antibiotics, corticosteroids, acetic acid, or a combination.

Geriatric Essentials

• In elderly patients with immunodeficiency or diabetes, external otitis occasionally progresses to necrotizing (malignant) external otitis, a potentially life-threatening osteomyelitis of the temporal bone.

External otitis is very common among people of all ages. Infection is usually precipitated by damage to the skin of the external auditory canal resulting from attempts to remove cerumen or retained water from the canal. Infection may also be precipitated by hearing aid use or, if recurrent, from seborrheic dermatitis. Water trapped in the canal after swimming or bathing may lead to external otitis.

Infection is usually caused by bacteria such as Pseudomonas aeruginosa, Proteus vulgaris, Staphylococcus aureus, or Escherichia coli. Occasionally, external otitis is caused by fungal overgrowth, most commonly Aspergillus and Candida spp. Fungal external otitis (otomycosis) can occur without apparent provocation or may occur after antibiotic ear drops are used to treat bacterial external otitis.

Symptoms and Signs

Symptoms include itching, pain, discharge, and swelling of the external auditory meatus. Swelling that completely obstructs the external auditory canal causes conductive hearing loss. Signs include erythema and swelling of the canal; scant, watery otorrhea mixed with desquamated debris; and pain when the pinnal, tragal, or mastoid tip near the external auditory canal is palpated.

Early in the course of fungal external otitis, itching in the ear is more common than pain. Thick, white debris with a velvety appearance or debris with hyphae is characteristic; swelling or edema of the external auditory meatus is less severe than that caused by bacterial external otitis.

In elderly patients with immunodeficiency or diabetes, external otitis occasionally progresses (despite treatment with antibiotic ear drops) to necrotizing (malignant) external otitis. Necrotizing external otitis is a potentially life-threatening osteomyelitis of the temporal bone that produces granulation tissue in the posterior inferior portion of the external auditory canal. Immunodeficiency and diabetic angiopathy may promote an invasive process. Once the infection penetrates the external auditory canal epithelium, it spreads along vascular and fascial planes, occasionally resulting in such complications as facial nerve paralysis, lateral venous sinus thrombosis, and paralysis of the 9th through 12th cranial nerves; it can extend to the contralateral temporal bone through the clivus.

Diagnosis

Diagnosis of external otitis is based on examination of the external auditory canal.

Necrotizing external otitis should be suspected if patients with diabetes do not respond promptly to treatment of routine external otitis or if they have otalgia disproportionate to clinical findings. Culture and sensitivity testing are done; P. aeruginosa is almost always detected. Technetium-99m bone scanning can detect temporal bone osteomyelitis early. Temporal bone CT, a secondary test, may show opacification of the mastoid air cell spaces or demineralization of bone, suggesting a more invasive disorder. Granulation tissue should be biopsied to rule out other inflammatory or neoplastic processes.

Treatment

During bathing or swimming, water may be prevented from entering the external ear canal by inserting a cotton ball impregnated with petroleum jelly or by inserting a premolded plastic earplug. Alternatively, an OTC or homemade 1:1 mixture of rubbing alcohol and vinegar can be instilled immediately after bathing. Alcohol helps dry the ear, and vinegar alters the pH, decreasing the risk of infection.

In patients with diffuse external otitis, topical antibiotics and corticosteroids are effective. The infected debris should be gently and thoroughly removed from the canal with suction or dry cotton wipes. Mild external otitis can be treated by altering the ear canal's pH with a solution of 2.5% acetic acid in 70% ethanol and by relieving inflammation with topical hydrocortisone (5 drops tid for 7 days). Moderate external otitis requires an additional 7 to 10 days of an antibacterial solution or suspension (eg, neomycin, polymyxin, bacitracin, ciprofloxacin); these antibiotics are often combined with a corticosteroid. If the tympanic membrane is perforated, a formulation without neomycin is recommended. Hearing aids should not be used until the infection resolves.

If swelling of the external auditory canal prevents instillation of antibiotic ear drops, a compressed, foam, polyvinyl acetate polymer wick should be gently inserted and wetted with the necessary drugs 4 times/day. The wick reduces swelling and enables the antibiotic to reach the deeper regions of the canal. The wick is left in place for 24 to 72 h, after which time the swelling may have receded enough to allow the instillation of drops directly into the canal. After the swelling resolves, the conductive hearing loss caused by the swelling also resolves.

Severe external otitis or cellulitis extending beyond the ear canal may require systemic antibiotics (eg, cephalexin 250 to 500 mg po qid or ciprofloxacin 500 mg po bid). If the patient is allergic to penicillin, erythromycin in the same dose can be used. An analgesic, such as an NSAID or even an oral opioid, may be necessary for the first 24 to 48 h.

Patients with necrotizing external otitis typically are treated for 6 wk with an oral fluoroquinolone (eg, ciprofloxacin 750 mg po bid). Gallium-67 scanning and ESR are used to monitor treatment response. Extensive bone disease may require more prolonged antibiotic therapy. Careful control of diabetes is essential. Surgery usually is not necessary.

For patients with fungal external otitis, the external auditory canal and tympanic membrane are meticulously cleaned under microscopic visualization. Then, 4 drops of clotrimazole (1% solution, qid for 7 to 10 days) are instilled in the affected ear.

This topic was last updated June 2006.