AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

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 and Hyperbaric 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:

• Acute diffuse otitis externa is the most common form of otitis externa and is most commonly seen in swimmers. Acute diffuse otitis externa is usually caused by bacteria, but it can be occasionally caused by a fungus. Elements of acute diffuse otitis externa include rapid onset (generally within 48 h); symptoms of ear canal inflammation that include otalgia, itching, or fullness, with or without hearing loss or jaw pain; and tenderness of the tragus or pinna, or diffuse ear edema or erythema or both, with or without otorrhea, regional lymphadenitis, tympanic membrane erythema, or cellulitis of the pinna.⁸
• Acute localized otitis externa, also known as furunculosis, is associated with infection of a hair follicle.
• Chronic otitis externa is the same as acute diffuse otitis externa, but it is of longer duration (>6 wk).
• Eczematous otitis externa encompasses various dermatologic conditions (eg, atopic dermatitis, psoriasis, lupus erythematosus, eczema) that may infect the external auditory canal and cause otitis externa. (See also the eMedicine articles Atopic Dermatitis [in the Dermatology section], Atopic Dermatitis [in the Pediatrics section], Psoriasis and Systemic Lupus Erythematosus [in the Emergency Medicine section], and Systemic Lupus Erythematosus [in the Rheumatology section].)
• Necrotizing "malignant" otitis externa is an infection that extends into the deeper tissues adjacent to the auditory canal. This type of otitis externa primarily occurs in adult patients who are immunocompromised (eg, diabetes mellitus, acquired immunodeficiency syndrome [AIDS]) and is rarely described in children. Necrotizing otitis externa may result in cases of cellulitis and osteomyelitis. (See also the eMedicine articles External Ear, Malignant External Otitis [in the Otolaryngology and Facial Plastic Surgery section], Cellulitis [in the Dermatology section], Cellulitis [in the Infectious Diseases section], Cellulitis and Osteomyelitis [in the Emergency Medicine section], and Osteomyelitis, Chronic [in the Radiology section].)

For excellent patient education resources, visit eMedicine's Ear, Nose, and Throat Center. Also, see eMedicine's patient education article Swimmer's Ear.

Pathophysiology

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.

Frequency

United States

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.

International

The international frequency of otitis externa is unknown; however, the incidence is increased in tropical countries.⁸

Mortality/Morbidity

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.

Race

No racial predilection is reported for otitis externa.

Sex

No sex predilection has been described for otitis externa.

Age

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.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

The patient may report the following symptoms:

• Otalgia
• Aural fullness
• Itching
• Discharge (Initially, the discharge may be clear and odorless, but it quickly becomes a purulent, foul-smelling discharge.)
• Decreased hearing
• Tinnitus
• Fever (uncommon)
• Bilateral symptoms (rare)

Physical

Findings of the physical examination may include the following:

• Tragal tenderness with manipulation
• Erythematous and edematous external auditory canal
• Purulent discharge
• Eczema of auricle
• Periauricular and cervical adenopathy
• Fever (uncommon)
• In severe cases, the infection may spread to the surrounding soft tissues, including the parotid gland. Bony extension may also occur into the mastoid bone, temporomandibular joint, and base of the skull, in which case cranial nerves VII (facial), IX (glossopharyngeal), X (vagus), XI (accessory), or XII (hypoglossal) may be affected.

Causes

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.

• Risk factors
• • Previous episodes of otitis externa
  • Swimming, diving, or participating in aquatic activities
  • Use of earplugs or probing of the external auditory canal (possibly secondary to trauma caused to the external auditory canal)
  • Hot, humid weather
  • Use of a hearing aid
  • Coexistence of eczema, allergic rhinitis, or asthma
  • Comorbidities such as diabetes mellitus, AIDS, leukopenia, or malnutrition (See also the eMedicine articles Diabetes Mellitus, Type 1 - A Review, Diabetes Mellitus, Type 2 - A Review, and HIV Infection and AIDS [in the Emergency Medicine section]; Diabetes Mellitus, Type 1 and Diabetes Mellitus, Type 2 [in the Endocrinology section], and Malnutrition [in the Pediatrics section], as well as the Medscape Diabetes Endocrinology Homepage, Diabetic Microvascular Complications Resource Center, Putting It Together: AIDS and the Millennium Development Goals, Global Survey Reveals Many People Do Not Think AIDS Is Fatal, Management of Eating Disorders in Children and Teens Reviewed, and Protein and Energy Supplementation in Elderly People at Risk From Malnutrition on Medscape.) 

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to Be Considered

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

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• The patient's history and physical examination usually provide adequate information to make the diagnosis of otitis externa.
• Typically, laboratory studies are not needed in the diagnosis of otitis externa. However, Gram stain and culture of any discharge from the auditory canal may be helpful if the patient is immunocompromised, treatment is failing, or if a fungal cause is suspected. However, up to 40% of all cases of otitis externa do not produce a dominant pathogen.

Imaging Studies

• Radiologic investigation may be helpful if an invasive infection is suspected or if the diagnosis of mastoiditis is being considered. Computed tomography (CT) scanning is preferred and better depicts bony erosion.¹⁰ A magnetic resonance imaging (MRI) study may be considered secondarily or if soft-tissue extension is the predominant concern. (See also the eMedicine articles Mastoiditis [in the Pediatrics section], Mastoiditis [in the Emergency Medicine section], and Middle Ear, Mastoiditis [in the Otolaryngology and Facial Plastic Surgery].)

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

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.

• Gently cleanse debris from the external auditory canal with irrigation or by using a soft plastic curette or cotton swab under direct visualization. Cleansing the canal improves the effectiveness of the topical medication.
• Topical aural medications typically include a mild acid (to alter the pH and to inhibit the growth of microorganisms), a corticosteroid (to decrease inflammation), an antibacterial agent, and/or an antifungal agent. Rosenfeld et al conducted a systematic review of treatment for otitis externa and demonstrated little overall difference in the topical agents that are used to treat otitis externa¹¹; however, the authors found that use of a topical steroid alone increased cure rates by 20% compared with a steroid/antibiotic combination.
• • Mild infections: Mild otitis externa usually responds to the use of an acidifying agent and a corticosteroid. As an alternative, a 2:1 ratio mixture of 70% isopropyl alcohol and acetic acid may be used.
  • Moderate infections: Consider the addition of antibacterial and antifungal agents to the acidifying agent and corticosteroid.
  • Oral antibiotics are generally reserved for use in patients with fevers, immunosuppression, diabetes, adenopathy, or in those individuals with extension of the infection outside of the ear canal.
  • In some cases, a gauze wick (1/4 inch in length) can be inserted into the canal, and the ototopic medication(s) can be applied directly to the wick (2-4 times daily depending upon the frequency of dosing for the medication). If a wick is used, it should be removed 24-72 hours after insertion.
  • In the setting of a patient with a tympanostomy tube or known perforation, a non-ototoxic topical preparation should be prescribed (eg, fluoroquinolone, with or without a steroid).
• In the setting of chronic, noninfectious, therapy-resistant external otitis, a prospective study by Caffier et al demonstrated that the daily use of 0.1% tacrolimus cream (via a wick that was changed every second to third day) resulted in high rates of resolution (46% through a 1-2 y follow-up) after 9-12 days of therapy.¹² The study also demonstrated longer periods of symptom-free intervals for those who experienced a recurrence.

Consultations

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).

Activity

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.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

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.

Drug Category: Analgesics

Pain control is essential to quality patient care. Analgesics ensure patient comfort and may have sedating properties.

Drug Category: Antibiotic/corticosteroid, Otic

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.

Drug Category: Antifungal Agent, Topical

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).

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Outpatient Care

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.

Deterrence/Prevention

• Several measures that are related to ear hygiene may be taken to help prevent recurrent otitis externa infections.
• • Eliminate any self-inflicted trauma to the ear canal, such as using cotton swabs or inserting objects into the external auditory canal.
  • Avoid frequent washing of the ears with soap, as this leaves an alkali residue that neutralizes the acidic pH of the ear canal.
  • Avoid swimming in polluted waters.
  • Ensure that the ear canals are emptied of water after swimming or bathing.
• Prophylactic ear drops: A combination of a 2:1 ratio of 70% isopropyl alcohol and acetic acid may be used after each episode of swimming to assist in drying and acidifying the ear canal.
• Generally, earplugs should be avoided due to the fact that these objects may cause trauma to the ear canal, thereby predisposing to the development of otitis externa.

Complications

• Complications of otitis externa include local purulent extension of disease, such as the following:
• • Necrotizing otitis externa
  • Mastoiditis
  • Chondritis of the auricle
  • Bony erosion of the base of the skull
  • Central nervous system (CNS) infection

Prognosis

• The patient may return to aquatic activities once the infection has been eradicated, generally within 4-5 days.
• Aquatic athletes may return to the pool earlier than 4-5 days; however, they need to keep their ear canals dry. Generally, after 2-3 days of refraining from any water activity, the athlete can return to water activities but the head should be kept dry until the infection has been eradicated.

Patient Education

• Otitis externa is a common problem with risk factors that can be easily avoided. Prevention of this common medical condition for aquatic athletes is the most important advancement in the past decade. When otitis externa does strike, the condition can usually be resolved in a short time with few complications.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Failure to recognize and appropriately treat the complications of otitis externa is the most significant medical/legal pitfall.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

1. Bojrab DI, Bruderly T, Abdulrazzak Y. Otitis externa. Otolaryngol Clin North Am. Oct 1996;29(5):761-82. [Medline].
2. Cantor RM. Otitis externa and otitis media. A new look at old problems. Emerg Med Clin North Am. May 1995;13(2):445-55. [Medline].
3. 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].
4. Osguthorpe JD, Nielsen DR. Otitis externa: review and clinical update. Am Fam Physician. Nov 1 2006;74(9):1510-6. [Medline]. [Full Text].
5. Russell JD, Donnelly M, McShane DP, Alun-Jones T, Walsh M. What causes acute otitis externa?. J Laryngol Otol. Oct 1993;107(10):898-901. [Medline].
6. Holten KB, Gick J. Management of the patient with otitis externa. J Fam Pract. Apr 2001;50(4):353-60. [Medline]. [Full Text].
7. Rowlands S, Devalia H, Smith C, Hubbard R, Dean A. Otitis externa in UK general practice: a survey using the UK General Practice Research Database. Br J Gen Pract. Jul 2001;51(468):533-8. [Medline]. [Full Text].
8. Hughes E, Lee JH. Otitis externa. Pediatr Rev. Jun 2001;22(6):191-7. [Medline].
9. Clark WB, Brook I, Bianki D, Thompson DH. Microbiology of otitis externa. Otolaryngol Head Neck Surg. Jan 1997;116(1):23-5. [Medline].
10. Grandis JR, Curtin HD, Yu VL. Necrotizing (malignant) external otitis: prospective comparison of CT and MR imaging in diagnosis and follow-up. Radiology. Aug 1995;196(2):499-504. [Medline]. [Full Text].
11. 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].
12. Caffier PP, Harth W, Mayelzadeh B, Haupt H, Sedlmaier B. Tacrolimus: a new option in therapy-resistant chronic external otitis. Laryngoscope. Jun 2007;117(6):1046-52. [Medline].
13. Bath AP, Walsh RM, Bance ML, Rutka JA. Ototoxicity of topical gentamicin preparations. Laryngoscope. Jul 1999;109(7 pt 1):1088-93. [Medline].
14. Beers SL, Abramo TJ. Otitis externa review. Pediatr Emerg Care. Apr 2004;20(4):250-6. [Medline].
15. Rosen P, Barkin RM, Hayden SR, Schaider JJ, Wolfe R. Otitis externa. The 5 Minute Emergency Medicine Consult. Philadelphia, Pa: Lippincott Williams & Wilkins; 1999:796-7.
16. Tintinalli JE, Kelen GD, Stapczynski JS, eds. Emergency Medicine: A Comprehensive Study Guide. 5^th ed. New York, NY: McGraw-Hill Professional Publishing; 2000:1521-3.

Article Last Updated: Nov 30, 2007