Introduction
Background
Otitis externa is an infection of the external ear canal and is a common problem in most EDs. Usually simple to care for, external otitis may lead to serious problems in people who are diabetic or immunocompromised. Basic treatment measures cure 90% of cases without complication.
Otitis externa is defined as chronic when the duration of the infection exceeds 4 weeks or when more than 4 episodes occur in 1 year.
Pathophysiology
Glands within the ear canal produce a layer of protective cerumen. Too little cerumen may predispose to infection, while too much cerumen may cause retention of water and debris. Most ear canal infections are caused by excessive moisture carrying bacteria into the cerumen of the ear canal, leading to maceration and inflammation. Another common cause is local trauma allowing bacteria to enter compromised skin. The most common causative organism is Pseudomonas species. Staphylococci, streptococci, and (in rare cases) fungi are other causative agents.
Otitis externa can also result from nonbacterial origins such as atopic dermatitis or allergic contact dermatitis.
Frequency
United States
Acute otitis externa occurs in 4 of every 1000 people each year, and the chronic form affects 3-5% of the population. The condition is most common in persons who are swimmers and/or divers or who have other exposures that allow contaminated water to be trapped in the external canal.
Mortality/Morbidity
Infection of the deep structures (ie, malignant external otitis) occurs almost exclusively in patients who are immunocompromised. People who are diabetic are particularly vulnerable.
- This complication should be suspected if tenderness, erythema, and edema of the external ear or adjacent tissues are present.
- This condition can lead to cellulitis and osteomyelitis, with the untreated mortality rate approaching 50%.
- When a fever, other signs of systemic toxicity, or underlying immunocompromise is present, the patient may need admission and treatment with high-dose antibiotics covering Pseudomonas species.
- Life-threatening temporal bone infection occurs in less than 0.5% of cases.
Race
People in some racial groups have small ear canals, which may predispose them to obstruction and infection.
Sex
Rates of occurrence are equal in males and females.
Age
All ages are affected, with a peak incidence in children aged 7-12 years.
Clinical
History
- In general, a history of 1-2 days of progressive ear pain
- Frequently, a history of exposure to water
- Itching
- Purulent discharge
- Conductive hearing loss
- Feeling of fullness or pressure
Physical
- The sine qua non of otitis externa is pain on gentle traction of the external ear.
- Periauricular adenitis may occur, but it is not necessary for the diagnosis.
- Speculum examination of the canal reveals erythema, edema of the epithelium, and accumulation of moist debris in the canal.
- The tympanic membrane may be difficult to visualize and may be mildly inflamed, but it should be normally mobile on insufflation.
- Spores and hyphae may be seen in the external canal, if the etiology is fungal.
- Eczema of the pinna may be present.
- By definition, cranial nerve (CN) involvement (ie, of CNs VII and IX-XII) is not associated with simple otitis externa.
Causes
- Traumatized external canal (particularly due to cotton-tipped swabs)
- Bacterial infection
- Pseudomonas species (38-50% of all cases)
- Staphylococcus species
- Gram-negative rods
- Fungal infection (rare, 10%) -Aspergillus species
- Yeast (rare) -Candida species
- Eczematous otitis externa
- Eczema
- Seborrhea
- Neurodermatitis
- Contact dermatitis from earrings or hearing aid use
- Purulent otitis media with perforation of the tympanic membrane and drainage (This may mimic findings in otitis externa, but it is usually painless and has no swelling of the canal.)
- Sensitivity to topical medications
- Chronic otitis externa is usually a result of nonbacterial sources as described above, but it can also result from inadequately treated acute otitis externa.
More on Otitis Externa |
 Overview: Otitis Externa |
| Differential Diagnoses & Workup: Otitis Externa |
| Treatment & Medication: Otitis Externa |
| Follow-up: Otitis Externa |
| Multimedia: Otitis Externa |
| References |
| Next Page » |
References
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Halpern MT, Palmer CS, Seidlin M. Treatment patterns for otitis externa. J Am Board Fam Pract. Jan-Feb 1999;12(1):1-7. [Medline].
Hickham M, Amedee RG. Malignant otitis externa. J La State Med Soc. Dec 1996;148(12):511-3. [Medline].
Mirza N. Otitis externa. Management in the primary care office. Postgrad Med. May 1996;99(5):153-4, 157-8. [Medline].
Niparko JK. Hearing loss and associated problems. In: Principles of Ambulatory Medicine. 4th ed. Lippincott Williams & Wilkins; 1995:1408-9.
Osguthorpe JD, Nielsen DR. Otitis externa: Review and clinical update. Am Fam Physician. Nov 2006;74(9):1510-6. [Medline].
Rosenfeld RM, Singer M, Wasserman JM, Stinnett SS. Systemic review of topical antimicrobial therapy for acute otitis externa. Otolaryngol Head Neck Surg. Apr 2006;134(4 Suppl):S24-48. [Medline].
van Asperen IA, de Rover CM, Schijven JF, et al. Risk of otitis externa after swimming in recreational fresh water lakes containing Pseudomonas aeruginosa. BMJ. Nov 25 1995;311(7017):1407-10. [Medline].
Further Reading
Keywords
otitis externa, ear ache, ear infection, OE, external ear canal infection, infection of the external ear canal, external otitis, swimmer's ear, malignant external otitis, malignant OE, eczematous otitis externa
