3.02 Otitis Externa (Swimmer’s Ear)

agk’s Library of Common Simple Emergencies

Presentation

The patient complains of ear pain, always uncomfortable and sometimes unbearable, often accompanied by drainage and a blocked sensation, sometimes by fever. When the condition is mild or chronic there may be itching rather than pain. Pulling on the auricle or pushing on the tragus of the ear classicly causes increased pain. The tissue lining the canal may be swollen and in severe cases the swelling can extend the the soft tissue surrounding the ear. Tender erythematous swelling or an underlying furuncle may be present, and it may be pointing or draining. The canal may be erythematous and dry or it may be covered with fuzzy cotton-like grayish or black fungal plaques. Most often, the canal lining is moist, covered with purulent drainage and debris, and cerumen is characteristically absent. The canal may be so swollen that it is difficult or impossible to view the tympanic membrane, which when seen often looks dull.

What to do:

• Suction out the debris and drainage present in the canal. Irrigation can be most effective in cleaning out the canal. Inspect for the presence of any foreign body.
• Incise and drain any furuncle that is pointing or fluctuant.
• If the ear canal is too narrow for medication to flow freely, insert a wick. Best is the Pope ear wick (Merocel), about 1 by 10 mm of compressed cellulose, which is thin enough to slip into bn occluded canal, but expands when wet. If not available, try using alligator forceps to insert quarter-inch gauze (but this is more painful). After a wick is inserted, water must be kept out of the ear, and the patient must be instructed to use soft wax ear plugs while showering.
• Prescribe a topical steroid solution for instillation down the wick (Otic Tridesilon Solution, Vosol HC, Acetasol HC, Corticosporin Solution or Suspension), every six to eight hours for the next 7-14 days. (Clear solutions are usually used, because they do not obscure follow up examination, but if there might be a perforation of the tympanic membrane, use a less-irritating suspension. Ophthalmic gentamycin solution is a good choice for pseudomonas. The antifungal cresyl acetate solution (Cresylate) may be used for a purely fungal infection.)
• With moderate to severe pain and slft tissue swelling, or other signs of cellulitis, prescribe an appropriate analgesic (e.g., acetaminophen, ibuprofen, naproxen, hydrocodone or oxycodone) and an antibiotic (e.g., trimethaprim plus sulfamethoxyzole, ciprofloxacin, dicloxicillin or cefadroxil) and have the patient use warm, moist compresses to help relieve any pain or swelling.
• Provide follow up in one to two days for removal of the wick and remaining debris from the ear canal.
• Have the patient use a prophylactic 2% acetic acid solution (e.g., Otic Domeboro Solution or half-strength vinegar) after swimming or bathing when the initial therapy has been completed.

What not to do:

• Do not use oral antibiotics for simple otitis externa without evidence of cellulitis or concurrent otitis media.
• Do not use topical antibiotics for prophylaxis. Long-term use of any topical antibiotics can lead to a fungal superinfection.
• Do not instill medication without first cleansing the ear canal, unless restricted because of pain.
• Do not expect medicine to enter a swollen-shut canal without a wick.
• Do not use ear drops containing neomycin, which sometimes causes allergic dermatitis.

Discussion

Otitis externa has a seasonal occurrence, being more frequently encountered in the summer months, when the climate and contaminated water will most likely precipitate a fungal or Pseudomonas aeruginosa bacterial infection. Various dermatoses, diabetes, aggressive ear cleaning with cotton-tipped applicators, previous external ear infections and furunculosis also predispose patients to developing otitis externa.

The healthy ear canal is coated with cerumen and sloughed epithelium. Cerumen is warer-repellant and acidic, and contains a number of antimicrobial substances. Repeated washing or cleaning can remove this defensive coating. Moisture retained in the ear canal is readily absorbed by the stratum corneum. The skin becomes macerated and edematous and the accumulation of debris may block gland ducts, preventing further production of the protective cerumen. Finally, endogenous or exogenous organizms invade the damaged canal epithelium and cause the infection.

Malignant or necrotizing external otitis is a life-threatening condition that occurs primarily in elderly diabetic patients as well as any immunocompromised individual. The pathognomonic sign of malignant external otitis is the presence of active granulation tissue in the ear canal. Early consultation should be obtained if there is any suspicion of this condition in a susceptable patient with a draining ear.

The ear is innervated by the fifth, seventh, ninth and tenth cranial nerves and the second and third cervical nerves. Because of this rich nerve supply, the skin is extremely sensitive. Otalgia may arise directly from the seventh cranial nerve (geniculate ganglion), ninth cranial nerve (tympanic branch), the external ear, the mastoid air cells, the mouth, teeth, or esophagus. Ear pain can result from sinusitis, trigeminal neuralgia and temperomandibular joint dysfunction opr be referred from disorders of the pharynx and larynx. A mild pain referred to the ear may be felt as itching, cause the patient to scratch the ear canal, and present as an external otitis. When the source of ear pain is not readily apparent, the patient should be referred for a more complete otolaryngologic investigation.

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