Introduction
Background
Otitis externa is an infection of the external auditory canal. Prompt diagnosis and treatment cures the majority of cases without complication. However, patients who are diabetic, immunocompromised, or untreated may develop malignant otitis externa, a potentially life-threatening infection.
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
The ear canal guards against infection by producing a protective layer of cerumen, which creates an acidic and lysozyme-rich environment. While a paucity of cerumen allows for bacterial growth, an excess can cause retention of water and debris, which can create an environment ideal for bacterial invasion. This may happen when the ear canal is regularly exposed to water as seen in swimmers and divers. Localized trauma from foreign objects placed in the ear can also lead to direct bacterial invasion in the ear canal. Once an infection becomes established, localized maceration and inflammation occur, which lead to symptoms.
Rarely, the bacterial infection can invade the deeper underlying structures of the soft tissue and destroy the underlying temporal bone. This is called malignant otitis externa and is a complication seen more often in immunocompromised patients.
The most common organism reported in otitis externa is the Pseudomonas species, followed by Staphylococcus and Streptococcus species. Fungi are a less common cause of otitis externa.1
Frequency
United States
Acute otitis externa occurs in 4 of every 1000 people annually, and the chronic form affects 3-5% of the population.2 The condition is most common in swimmers, divers, and those whose ears are regularly exposed to or submerged in water.
Mortality/Morbidity
If left untreated, the infection may invade the deeper adjacent structures and progress into malignant otitis externa. This complication is almost exclusively seen in immunocompromised patients such as those with diabetes, AIDS patients, those undergoing chemotherapy, and patients taking immunosuppressant medications such as glucocorticoids. Pseudomonas is the inciting organism in the vast majority of cases. When untreated, malignant otitis externa has a mortality rate approaching 50%. This complication should be suspected if tenderness, erythema, or edema of the external ear or adjacent tissues is present on physical examination.
Race
People in some racial groups have small ear canals, which may predispose them to obstruction and infection.
Sex
Rates of occurrence of otitis externa are equal in males and females.
Age
Although otitis externa is seen in all age groups, the peak incidence is in children aged 7-12 years.1
Clinical
History
- In general, a history of 1-2 days of progressive ear pain
- Frequently, a history of exposure to water
- Pruritus within the ear canal
- 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 structures.
- Periauricular adenitis may occur but is not necessary for the diagnosis.
- Examination of the canal reveals erythema, edema, and narrowing of the external auditory canal.
- Typically, accumulation of moist debris is observed in the external 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 of all cases)1
- 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
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
Roland PS, Stroman DW. Microbiology of acute otitis externa. Laryngoscope. Jul 2002;112(7 Pt 1):1166-77. [Medline].
Osguthorpe JD, Nielsen DR. Otitis externa: Review and clinical update. Am Fam Physician. Nov 1 2006;74(9):1510-6. [Medline].
Wall GM, Stroman DW, Roland PS, Dohar J. Ciprofloxacin 0.3%/dexamethasone 0.1% sterile otic suspension for the topical treatment of ear infections: a review of the literature. Pediatr Infect Dis J. Feb 2009;28(2):141-4. [Medline].
[Guideline] Rosenfeld RM, Brown L, Cannon CR, et al. Clinical practice guideline: acute otitis externa. Otolaryngol Head Neck Surg. Apr 2006;134(4 Suppl):S4-23. [Medline]. [Full Text].
Roland PS, Belcher BP, Bettis R, Makabale RL, Conroy PJ, Wall GM, et al. A single topical agent is clinically equivalent to the combination of topical and oral antibiotic treatment for otitis externa. Am J Otolaryngol. Jul-Aug 2008;29(4):255-61. [Medline].
Beers SL, Abramo TJ. Otitis externa review. Pediatr Emerg Care. Apr 2004;20(4):250-6. [Medline].
Block SL. Otitis externa: providing relief while avoiding complications. J Fam Pract. Aug 2005;54(8):669-76. [Medline].
Kim D, Bhimani M. Ramsay Hunt syndrome presenting as simple otitis externa. CJEM. May 2008;10(3):247-50. [Medline].
Niparko JK. Hearing loss and associated problems. In: Principles of Ambulatory Medicine. 4th ed. Lippincott Williams & Wilkins; 1995:1408-9.
Rahman A, Rizwan S, Waycaster C, Wall GM. Pooled analysis of two clinical trials comparing the clinical outcomes of topical ciprofloxacin/dexamethasone otic suspension and polymyxin B/neomycin/hydrocortisone otic suspension for the treatment of acute otitis externa in adults and children. Clin Ther. Sep 2007;29(9):1950-6. [Medline].
Rosenfeld RM, Singer M, Wasserman JM, Stinnett SS. Systematic review of topical antimicrobial therapy for acute otitis externa. Otolaryngol Head Neck Surg. Apr 2006;134(4 Suppl):S24-48. [Medline].
Further Reading
Keywords
otitis externa, swimmer's ear, ear ache, ear infection, otitis externa treatment, otitis externa symptoms, external ear canal infection, external otitis, malignant external otitis, eczematous otitis externa, malignant otitis externa
