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Acute Otitis Externa
ALTERNATIVE NAMES: Swimmer's ear; external canal infection.
DEFINITION: Inflammation or infection of the tissues of the external canal.
WHAT IS GOING ON IN MY BODY? Acute otitis externs is inflammation or infection of the auricle and external canal, the two structures that form the external or outer ear. They are involved in transmitting sound from the environment into the middle ear space. The auricle and its shape are designed to concentrate and collect sound and direct it down toward the tympanic membrane through the external canal. Contained within the outer ear canal are a number of glands, including oil, sweat, and ear wax (cerumen) glands. Ear wax actually has an important function in that it helps maintain a fairly acidic environment in the ear canal. Interestingly, diabetics who are prone to ear canal infections have an increase in the alkaline level of their ear wax, which is thought to be one of the mechanisms by which ear canal infections occur.
Another form of otitis externs is if there is an infection in the hair follicles of the ear canal. This is termed folliculitis. If the infected hair follicle is unable to drain, an abscess can form.
WHAT ARE THE SIGNS AND SYMPTOMS? Typically patients complain of discolored ear drainage, intense pain, and diminished hearing. These symptoms are quite similar to that seen in acute otitis media. Whereas acute otitis media typically affects individuals under the age of six, otitis externa is usually an illness beginning in late childhood. What is also somewhat different is the amount of tenderness or pain on contact around the opening of the ear canal and around the outer portion of the ear. Occasionally the infection can start to affect the tissue in front of and below the ear with pain, tenderness, and swelling. This occurs as the infection in the ear canal moves through small holes in the cartilage of the outer ear canal and then into the surrounding soft tissue.
These patients, when examined, often have extensive swelling of the outer ear canal with infected material. Any contact around the opening to the ear canal is exquisitely painful, particularly placement of the speculum of the otoscope, the instrument used to examine the ear canal, the eardrum, and the space behind the eardrum. There may be ear wax and shedding of the superficial layer of the ear canal skin in the ear canal itself.
If there is an infected hair follicle, usually the only portion of the ear canal that is affected is the infected follicle itself. There may be a localized area of swelling, redness, and tenderness. As opposed to acute otitis externs where the entire ear canal is infected, only a small isolated portion of the outermost hair-bearing aspect of the external canal is involved.
WHAT ARE THE CAUSES AND RISKS? The main cause of acute otitis externs is water contamination, thus the term swimmer's ear. Water left in the ear canal provides a perfect environment for infection. The dampness plus ear wax and shed skin is a perfect breeding ground. As previously mentioned, because of lower levels of acidity of the ear wax in diabetics, diabetics are at a greater risk for ear canal infections. Individuals with very narrow openings into the ear canal or those who have benign bone growths in the ear canal (osteomas) do not allow water to drain out effectively, thus promoting infection. Chronic irritation of the ear canal (chronic otitis externs) may predispose individuals also to the formation of acute ear canal infections. Fungal infections may also occur in the ear canal and present with acute signs and symptoms. These often do not respond as rapidly to oral or topical antibiotics and may require specific topical antifungal therapy. Not infrequently the infected material from a fungal infection is a mix of dark gray/white/yellow pus that may have mold fruiting bodies on its surface.
The main risk of acute otitis externa is facial cellulitis and in susceptible individuals with compromised immune states, such as diabetics, extension of the infection into the bone of the ear canal and temporal bone (malignant otitis externa).
Causes of ear canal hair follicle infections are unclear.
HOW TO PREVENT THE DISEASE: Since water contamination is a major factor, ensuring complete removal of water from the outer ear canal is important. This can be facilitated by using a mixture of peroxide and rubbing alcohol ear drops. This peroxide/alcohol combination should not be used if there is a hole in the eardrum. Individuals who have suffered from previous ear canal infections would be wise to ensure adequate dryness of the ear canal itself. White table vinegar can also be helpful when applied in drops to the ear canal because of its benefit in restoring an acid environment to the ear canal.
HOW IS IT DIAGNOSED? The main method of diagnosis is examination of the outer ear canal. Cultures can sometimes be helpful, particularly if the infection is not responding to otherwise appropriate treatments.
WHAT ARE THE LONG-TERM EFFECTS? Frequent recurrent acute otitis externa or incompletely treated otitis externs can cause the skin of the ear canal to thicken, thus narrowing the ear canal. At times significant scarring can form, with subsequent replacement of the ear canal skin by scar tissue, which can prevent sound from effectively contacting the tympanic membrane. As mentioned previously, delayed or inappropriate treatment in a diabetic puts them at risk for malignant otitis externs.
AM I PUTTING OTHERS AT RISK? No.
WHAT ARE THE TREATMENTS? The mainstay of therapy is antibiotic- and steroid-containing ear drops. It is very important also to have the ear wax and shed skin removed. If there is extension of the infection into the soft tissues around the ear, oral antibiotics may be necessary. If the ear canal is particularly swollen, placement of a wick to draw the ear drops in is beneficial. Treatment for infected hair follicles would be very similar. Other treatments include steroid and acidic acid (vinegar) therapies.
WHAT ARE THE SIDE EFFECTS TO THE TREATMENTS? The main side effects would be those seen with the various medications employed. One of the most common topical antibiotic solutions contains Neomycin. Individuals can have a Neomycin skin sensitivity, which causes a reaction in the ear canal very similar to poison ivy. Therefore, if the patient continues to have significant swelling of the ear canal and itching, then the Neomycin containing antibiotic needs to be stopped and other treatments instituted.
WHAT HAPPENS AFTER TREATMENT? Successful treatment restores the ear canal or hair follicles to their pre-existent healthy state. There is usually complete resolution of symptoms.
HOW DO I MONITOR THE DISEASE? The disease is mostly monitored by the severity of symptoms. If a patient begins to notice early swelling, ear canal tenderness, and pain, white table vinegar irrigations or drops may help halt its progression. If the symptoms continue to intensify, then medical attention needs to be sought. Any spread of the infection into the soft tissues around the ear or other unusual symptoms, such as dizziness or facial weakness, are medical emergencies and require immediate attention.
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