Otitis externa ("swimmer's ear") is an inflammation of the outer ear and ear canal. Along with otitis media, external otitis is one of the two human conditions commonly called "earache". It also occurs in many other species. Inflammation of the skin of the ear canal is the essence of this disorder. The inflammation can be secondary to dermatitis (eczema) only, with no microbial infection, or it can be caused by active bacterial or fungal infection. In either case, but more often with infection, the ear canal skin swells and may become painful and/or tender to touch.
The skin of the bony ear canal is unique, in that it is not movable but is closely attached to the bone, and it is almost paper thin. For these reasons it is easily abraded or torn by even minimal physical force. Inflammation of the ear canal skin typically begins with a physical insult, most often from injury caused by attempts at self-cleaning or scratching with cotton swabs, pen caps, finger nails, hair pins, keys, or other small implements. Another causative factor for acute infection is prolonged water exposure in the forms of swimming or exposure to extreme humidity, which can compromise the protective barrier function of the canal skin, allowing bacteria to flourish; hence the name, "swimmer's ear". Densely impacted wax, usually caused by enthusiastic use of cotton swabs, can put enough pressure on the ear canal skin to injure it and initiate infection. A sensation of blockage or itching can prompt attempts to clean, scratch, or open the ear canal, which potentially worsens and perpetuates the condition. The cotton fibers of a swab are abrasive to the thin, fixed canal skin. Self-manipulative measures to improve the condition often make it worse and are to be discouraged, since it is a blind exercise that can result in significant injury to the ear. Production of wax by glands in the canal may be hindered by external otitis. The exact function(s) of cerumen (earwax) is a subject that is open to speculation, since there is very little research regarding its function. Some caretakers feel strongly that earwax has a protective function with respect to infection and that a little earwax in the ear canal is a good thing. A natural question is, "How can I clean my ears, then?" It is well established that in most people the top layer of the ear canal skin normally migrates toward the ear opening, essentially sweeping the canal on a continuing basis. In other words, a normal ear canal is self-cleaning. This self-cleaning physiologic feature fails in some patients, especially in late life, and periodic cleaning by a physician can be necessary. The most controlled and least painful means of cleaning impacted wax or dead skin from the ear canal is by using a binocular surgical microscope, which frees the examiner's hands to instrument the ear and provides the magnification and depth perception needed to avoid traumatizing the delicate canal skin and eardrum.
Due to the fact that the ear and throat are often interconnected, irritation (whether it be in inflammation or a scratching sensation) is normal. However, excessive throat symptoms may likely point to the throat as the cause of the pain in the ear rather than the other way around.
Because the symptoms of external otitis promote many people to attempt to clean out the ear canal (or scratch it) with slim implements, and self-cleaning attempts generally lead to additional trauma of the injured skin, rapid worsening of the condition often occurs.
The two factors that are required for external otitis to develop are (1) the presence of germs that can infect the skin and (2) impairments in the integrity of the skin of the ear canal that allow infection to occur. If the skin is healthy and uninjured, only exposure to a high concentration of pathogens, such as submersion in a pond contaminated by sewage, is likely to set off an episode. However, if there are chronic skin conditions that affect the ear canal skin, such as atopic dermatitis, seborrheic dermatitis, psoriasis or abnormalities of keratin production, or if there has been a break in the skin from trauma, even the normal bacteria found in the ear canal may cause infection and full-blown symptoms of external otitis.
Fungal ear canal infections, also known as otomycosis, range from inconsequential to very severe. Fungus can be saprophytic, in which there are no symptoms and the fungus simply co-exists in the ear canal in a harmless parasitic relationship with the host, in which case the only physical finding is presence of the fungus. If for any reason the fungus begins active reproduction, the ear canal can fill with dense fungal debris, causing pressure and ever-increasing pain that is unrelenting until the fungus is removed from the canal and anti-fungal medication is used. Most antibacterial ear drops also contain a steroid to hasten resolution of canal edema and pain. Unfortunately such drops make fungal infection worse. Prolonged use of them promotes growth of fungus in the ear canal. Antibacterial ear drops should be used a maximum of one week, but 5 days is usually enough. Otomycosis responds more than 95% of the time to a three day course of the same over-the-counter anti-fungal solutions used for athlete's foot.
The incidence of otitis externa is high. In the Netherlands, it has been estimated at 12-14 per 1000 population per year, and has been shown to affect more than 1% of a sample of the population in the United Kingdom over a 12 month period.
The diagnosis may be missed in early cases because the examination of the ear, with the exception of pain with manipulation, is normal or nearly normal. In some cases of early external otitis, the most striking visual finding in the ear canal is the lack of cerumen. As a moderate or severe case of external otitis resolves, weeks may be required before the ear canal again shows a normal amount of cerumen.
Topical solutions or suspensions in the form of ear drops are the mainstays of treatment for external otitis. Some contain antibiotics, either antibacterial or antifungal, and others are simply designed to mildly acidify the ear canal environment to discourage bacterial growth. Some prescription drops also contain anti-inflammatory steroids, which help to resolve swelling and itching. Although there is evidence that steroids are effective at reducing the length of treatment time required, fungal otitis externa (also called otomycosis) may be caused or aggravated by overly prolonged use of steroid-containing drops. In addition to topical antibiotics, oral anti-pseudomonal antibiotics can be used in case of severe soft tissue swelling extending into the face and neck and may hasten recovery.
Removal of debris (wax, shed skin, and pus) from the ear canal promotes direct contact of the prescribed medication with the infected skin and shortens recovery time. This is best accomplished using a binocular microscope. When canal swelling has progressed to the point where the ear canal is blocked, topical drops may not penetrate far enough into the ear canal to be effective. The physician may need to carefully insert a wick of cotton or other commercially available, pre-fashioned, absorbent material called an ear wick and then saturate that with the medication. The wick is kept saturated with medication until the canal opens enough that the drops will penetrate the canal without it. Removal of the wick does not require a health professional. Antibiotic ear drops should be dosed in a quantity that allows coating of most of the ear canal and used for no more than 4 to 7 days. The ear should be left open. Do note that it is imperative that there is visualization of an intact tympanic membrane. Use of certain medications with a ruptured tympanic membrane can cause tinnitus, vertigo, dizziness and hearing loss in some cases.
Although the acute external otitis generally resolves in a few days with topical washes and antibiotics, complete return of hearing and cerumen gland function may take a few more days. Once healed completely, the ear canal is again self-cleaning. Until it recovers fully, it may be more prone to repeat infection from further physical or chemical insult.
Effective medications include ear drops containing antibiotics to fight infection, and corticosteroids to reduce itching and inflammation. In painful cases a topical solution of antibiotics such as aminoglycoside, polymyxin or fluoroquinolone is usually prescribed. Antifungal solutions are used in the case of fungal infections. External otitis is almost always predominantly bacterial or predominantly fungal, so that only one type of medication is necessary and indicated.
The pain of acute otitis externa is often severe enough to interfere with sleep. Topical analgesic drops often prescribed by primary care providers for pain relief are almost never adequate and should not be relied upon. A brief course of oral narcotic pain medication is often necessary to maintain comfort while the antibiotic drops are working. Improvement with appropriate initial treatment (cleaning of the canal, wick insertion if necessary, and antibiotic drops in adequate amount) is fairly rapid, with pain improvement occurring within one day and resolution within 2-4 days. Heat application using a heating pad, can also aid in pain relief, although it may increase the bacteria growth.
Effective solutions for the ear canal include acidifying and drying agents, used either singly or in combination. When the ear canal skin is inflamed from the acute otitis externa, the use of dilute acetic acid may be painful.
Burow's solution is an effective remedy against both bacterial and fungal external otitis. This is a buffered mixture of aluminium sulfate and acetic acid, and is available without prescription in the United States.
Declining susceptibility to neomycin and polymyxin B of pathogens recovered in otitis externa clinical trials.(Original Article)
May 01, 2004; Background: Otitis externa is usually treated empirically with topical neomycin/polymyxin B/hydrocortisone. The predominant...