Updated: Nov 30, 2007
Otitis externa is an inflammation or infection of the external auditory canal and/or auricle.1,2,3 This condition is one of the most common medical conditions that affect aquatic athletes. Individuals with allergic conditions, such as eczema, allergic rhinitis, or asthma, also have a significantly higher risk of developing this condition.4,5 (See also the eMedicine articles Otitis Externa [in the Emergency Medicine section], Otitis Externa and Allergic Rhinitis [in the Pediatrics section], Allergic and Environmental Asthma [in the Allergy and Immunology section], and Allergic Rhinitis [in the Otolaryngology and Facial Plastic Surgery section], as well as Guidelines Issued for Acute Otitis Externa andHyperbaric Oxygen as an Adjuvant Treatment for Malignant Otitis Externa on Medscape.)
Several factors can contribute to the development of otitis externa. Absence of cerumen, high humidity, increased temperature, and local trauma (eg, use of cotton swabs or hearing aids) can result in infection of the canal.6 Aquatic athletes are particularly prone to the development of otitis externa because repeated exposure to water results in removal of cerumen and drying of the external auditory canal. Otitis externa occurs more often in the summer months when swimming is more common,6,7 and this condition is also common in tropical areas.8 The most common bacterial causes of otitis externa are Pseudomonas aeruginosa and Staphylococcus aureus.9
Otitis externa can be classified as follows:
For excellent patient education resources, visit eMedicine's Ear, Nose, and Throat Center. Also, see eMedicine's patient education article Swimmer's Ear.
The external auditory canal is lined with squamous epithelium and is approximately 2.5 cm in length in adults. The function of the external auditory canal is to transmit sound to the middle ear while protecting more proximal structures from foreign bodies and any changes in environmental conditions. The outer one third of the canal is primarily cartilaginous and is oriented superiorly and posteriorly; this portion of the canal contains cerumen-producing apocrine glands. The inner two thirds of the canal is osseous, covered with thin skin that is tightly adhered, and oriented inferiorly and anteriorly; this portion of the canal is devoid of any apocrine glands or hair follicles.
The quantity of cerumen that is produced varies widely among individuals. Cerumen is generally acidic (pH 4-5), thus inhibiting bacterial or fungal growth. The waxy nature of the cerumen protects the underlying epithelium from maceration or skin breakdown.
Otitis externa likely develops in aquatic athletes or swimmers as a result of excessive water exposure that results in an overall reduction in cerumen. This reduction in cerumen can then lead to drying of the external auditory canal and pruritus. The pruritus can then lead to probing of the external auditory canal, resulting in skin breakdown and an entry site for infection. Obstruction of the external auditory canal by excessive cerumen, debris, surfer's exostosis, or a narrow and tortuous canal may also lead to infection by means of moisture retention.
The most common offending organisms are P aeruginosa (50%), S aureus (23%), anaerobes and gram-negative organisms (12.5%), and fungi such as the Aspergillus and Candida species (12.5%). Otomycosis is an infection in the external auditory canal that is caused by the Aspergillus species 80-90% of the time. This condition is characterized by many long, white, filamentous hyphae that grow from the skin surface.
In one study, 91% of cases of external otitis were caused by bacteria.9 Elsewhere, up to 40% of cases of external otitis have no primary identifiable microorganism as a causative agent.
Annually, otitis externa occurs in 4 of every 1000 persons.4,6 The incidence is higher during the summer months, presumably because participation in aquatic activities is higher.6,7 Acute, chronic, and eczematous otitis externa are also common. Necrotizing otitis externa is rare.
The international frequency of otitis externa is unknown; however, the incidence is increased in tropical countries.8
The morbidity is low in aquatic athletes with acute diffuse otitis externa. However, in the event of the development of necrotizing otitis externa, there is a 20% mortality rate among adults, generally due to the associated comorbidities and the rapid extension of the infection to include sepsis or intracranial extension.
No racial predilection is reported for otitis externa.
No sex predilection has been described for otitis externa.
Generally, no association between the development of otitis externa and age exists. A single epidemiologic study in the United Kingdom found a similar 12-month prevalence for individuals aged 5-64 years and a slight increase in the prevalence for those older than 65 years.7 This was postulated to occur secondary to an increase in comorbidities, as well as an increase in the use of hearing aids, which may cause trauma to the external auditory canal.
The patient may report the following symptoms:
Findings of the physical examination may include the following:
The causes of otitis externa can be categorized as (1) obstructive (eg, cerumen, surfer's exostosis, narrow or tortuous canal), resulting in water retention; (2) absence of cerumen, which may occur as a result of repeated water exposure; (3) trauma; and (4) an alteration of the pH of the canal.
Facial Soft Tissue Injuries
Barotrauma (in the Emergency Medicine section) (See also Barotrauma and Mechanical Ventilation [in the Pulmology section].)
Dysbarism
Foreign Bodies, Ear (in the Emergency Medicine section) (See also Foreign Body Removal, Ear, [in the Clinical Procedures section].)
Herpes Zoster (in the Infectious Diseases section) (See also the eMedicine articles Postherpetic Neuralgia [in the Neurology section], Herpes Zoster [in the Emergency Medicine section], and Herpes Zoster [in the Dermatology section].)
Mastoiditis (in the Emergency Medicine section) (See also Mastoiditis [in the Pediatrics section].)
Otitis Media
Ramsay Hunt Syndrome
The primary treatment of otitis externa involves the management of pain, removal of debris from the external auditory canal, use of topical medications to control edema and infection, and avoidance of the contributing factors.
Consult an otorhinolaryngologist for patients whose cases are refractory to treatment regimens, for those with necrotizing otitis externa, and for those who develop any complications (see Complications).
Individuals who are involved in aquatic activities should keep the ear dry during the course of treatment for otitis externa. This may be accomplished by avoiding aquatic activities all together, but more often, it is achieved by limiting water activities to those that do not expose the ear to the water (eg, kicking while using a foam floatation board to keep the head above water). Typically, a swimming athlete with otitis externa spends the first 2-3 days out of the water, and then he or she may return to the water activity but should continue to keep the head above the water until the symptoms resolve.
Most cases of otitis externa can be treated with over-the-counter analgesia and antibiotic eardrops. In severe cases, oral or intravenous (IV) antibiotic therapy and narcotic analgesics may be required. In the case of necrotizing otitis externa, the patient must be admitted to a hospital for IV antibiotics at the discretion of the consulting otorhinolaryngologist. The treatment that is rendered is dependent on the likely organism, which is best evaluated with a Gram stain of the affected area.
Pain control is essential to quality patient care. Analgesics ensure patient comfort and may have sedating properties.
Over-the-counter acetaminophen is appropriate for most patients. DOC for pain in patients with documented hypersensitivity to aspirin or NSAIDs, with upper GI disease, or who are taking oral anticoagulants.
650-1000 mg PO q6h prn
10-15 mg/kg PO q4h prn
Rifampin can reduce the analgesic effects of acetaminophen; coadministration with barbiturates, carbamazepine, hydantoins, and isoniazid may increase hepatotoxicity.
Documented hypersensitivity; known G6PD deficiency
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Hepatotoxicity is possible following various dose levels in those with chronic alcoholism; severe or recurrent pain or high or continued fever may indicate a serious illness; APAP is contained in many OTC products, and combined use with these products may result in cumulative APAP doses that exceed the recommended maximum dose.
Indicated for the treatment of mild to moderate pain
30-60 mg/dose based on codeine content PO q4-6h or 1-2 tab PO q4h; not to exceed 4 g/d of acetaminophen
0.5 mg/kg/dose based on codeine content PO q4-6h; 10-15 mg/kg/dose based on acetaminophen content; not to exceed 2.6 g/d of acetaminophen
Toxicity increases with CNS depressants or tricyclic antidepressants
Documented hypersensitivity
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Caution in patients who are dependent on opiates because this substitution may result in acute opiate-withdrawal symptoms; caution in patients with severe renal or hepatic dysfunction
Most cases of otitis externa are caused by superficial bacterial infections. The small amount of steroid that is present in the solution can help to ease the pain and edema associated with this condition.
Compounded medication. Each mL contains 3 mg of gentamicin sulfate and 1 mg of betamethasone sodium phosphate
2-3 gtt on affected side qid
Administer as in adults
Coadministration with other aminoglycosides, cephalosporins, penicillins, and amphotericin B may increase nephrotoxicity; aminoglycosides enhance the effects of neuromuscular blocking agents, thus prolonged respiratory depression may occur; coadministration with loop diuretics may increase the ototoxicity of aminoglycosides; possible irreversible hearing loss of varying degrees may occur (monitor regularly).
Documented hypersensitivity; patients with non–dialysis-dependent renal insufficiency
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Some literature suggests that ototoxicity (hearing loss) is caused by the topical otic gentamicin, but the relationship is not clear at this time; narrow therapeutic index (not intended for long-term therapy); caution in patients with renal failure (not on dialysis), myasthenia gravis, hypocalcemia, and conditions that depress neuromuscular transmission; adjust dose in patients with renal impairment
This otic suspension is indicated for use in otitis externa, as well as otitis media in individuals with tympanostomy tubes.
4 gtt in affected external auditory canal bid × 7 d
< 6 months: Not indicated
>6 months: 4 gtt in affected external auditory canal bid × 7days.
None reported
Documented hypersensitivity; viral infections affecting external ear canal (eg, herpes simplex)
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
For otic use only; warm bottle in hand and shake well before administration; avoid contaminating applicator tip; prolonged use may cause bacterial or fungal overgrowth (discontinue if superinfection or hypersensitivity occurs); rare adverse effects include ear discomfort, ear pain, ear residue, and ear pruritus; re-evaluate if no improvement after 7 d.
A small but significant percentage of otitis externa cases are due to the Aspergillus species. The mechanism of action usually involves inhibiting the pathways (eg, enzymes, substrates, transport) that are necessary for sterol/cell membrane synthesis or for altering the permeability of the fungal cell membrane (eg, polyenes).
Compounded medication. Broad-spectrum antifungal agent that inhibits yeast growth by altering cell membrane permeability, causing death of fungal cells.
4 gtt qid into affected side
Administer as in adults
None reported
Documented hypersensitivity
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Not for treatment of systemic fungal infections; avoid contact with the eyes; if irritation or sensitivity develops, discontinue use and institute appropriate therapy
Follow-up is important in order to ascertain the patient's response to treatment for otitis externa. Even in mild cases, the patient should be reassessed 2-3 days following the initiation of treatment.
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swimmer's ear, acute diffuse otitis externa, acute localized otitis externa, necrotizing otitis externa, eczematous otitis externa, infection of the external auditory canal
Joseph P Garry, MD, FACSM, FAAFP,, Director of Sports Medicine and Sports Medicine Fellowship, Associate Professor of Family Medicine and Exercise and Sport Science, Department of Family Medicine, East Carolina University Brody School of Medicine
Joseph P Garry, MD, FACSM, FAAFP, is a member of the following medical societies: American Academy of Family Physicians, American College of Sports Medicine, American Heart Association, American Medical Society for Sports Medicine, and North American Primary Care Research Group
Disclosure: Nothing to disclose.
Sanjiv K Bhalla, MD, Consulting Staff, Department of Emergency Medicine, St Paul's Hospital of Vancouver, St Joseph's Hospital of Hamilton
Sanjiv K Bhalla, MD is a member of the following medical societies: American College of Emergency Physicians, British Columbia Medical Association, Canadian Association of Emergency Physicians, Canadian Medical Association, Canadian Medical Protective Association, and Ontario Medical Association
Disclosure: Nothing to disclose.
Andrew L Sherman, MD, MS, Associate Professor of Clinical Rehabilitation Medicine, Vice Chairman, Chief of Spine and Musculoskeletal Services, Program Director, SCI Fellowship and PMR Residency Programs, Department of Rehabilitation Medicine, Leonard A Miller School of Medicine, University of Miami
Andrew L Sherman, MD, MS is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, American Association of Neuromuscular and Electrodiagnostic Medicine, American College of Sports Medicine, American Medical Association, American Paraplegia Society, American Spinal Injury Association, and Association of Academic Physiatrists
Disclosure: pfizer Honoraria Speaking and teaching
Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment
Russell D White, MD, Professor of Medicine, Department of Community and Family Medicine, University of Missouri-Kansas City School of Medicine, Truman Medical Center Lakewood
Disclosure: Nothing to disclose.
Jon B Whitehurst, MD, Clinical Instructor of Surgery, University of Illinois College of Medicine; Partner and Executive Board Member, Rockford Orthopedic Associates; Orthopedic Chairman, Rockford Memorial Hospital
Jon B Whitehurst, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Society for Sports Medicine, and Arthroscopy Association of North America
Disclosure: Nothing to disclose.
Craig C Young, MD, Professor, Departments of Orthopedic Surgery and Community and Family Medicine, Medical Director of Sports Medicine, Sports Medicine Fellowship Director, Medical College of Wisconsin
Craig C Young, MD is a member of the following medical societies: American Academy of Family Physicians, American College of Sports Medicine, American Medical Society for Sports Medicine, and Phi Beta Kappa
Disclosure: Nothing to disclose.
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