eMedicine Specialties > Pediatrics: Surgery > Otolaryngology

Otitis Externa

Author: Ariel A Waitzman, MD, FRCS(C), Assistant Professor of Otolaryngology, Wayne State University
Contributor Information and Disclosures

Updated: Mar 14, 2008

Introduction

Background

Otitis externa (OE) is a common disease affecting all age groups.¹ OE usually represents an acute bacterial infection of the skin of the ear canal but can be caused by a fungal infection. Although OE rarely causes prolonged problems or serious complications, the infection is responsible for significant pain and acute morbidity.

Pathophysiology

OE is a superficial infection of the skin in the ear canal. Two common initiating events may lead to OE. If trapped in the ear canal, moisture may cause maceration of the skin and provide a good breeding ground for bacteria. This may occur after swimming (especially in contaminated water) or bathing, hence the common lay-term swimmer's ear. It may also occur in hot humid weather (when OE is more prevalent).

The second significant factor is trauma to the ear canal that allows invasion of bacteria into the damaged skin. This often occurs after attempts at cleaning the ear with a cotton swab, paper clip, or any other utensil that can fit into the ear.

Once infection is established, an inflammatory response occurs with skin edema. Exudate and pus often appear in the ear canal as well. If severe, the infection may spread and cause a cellulitis of the face or neck. The most common pathogen is Pseudomonas aeruginosa, followed by Staphylococcus aureus, then other gram-negative organisms. Occasionally, fungi, such as Candida or Aspergillus species, cause OE.

Necrotizing (or malignant) OE is a complication that occurs in patients who are immunocompromised or in those who have received radiotherapy to the skull base. In this condition, bacteria invade the deep soft tissues and cause osteomyelitis of the temporal bone. This is a life-threatening disorder with an overall mortality rate that approached 50% historically.

Frequency

United States

OE is a very common disease that occurs in all regions of the United States. The infection is believed to be more prevalent in hot and humid conditions.

International

Although OE is a very common disease that occurs worldwide, the infection is believed to be more prevalent in hot and humid conditions.

Mortality/Morbidity

• OE can cause severe otalgia requiring narcotic pain relievers in some patients.
• Temporary hearing loss is common secondary to canal occlusion.
• Severe infections may cause lymphadenitis or cellulitis of the face or neck.
• Necrotizing OE is a serious condition that requires prolonged treatment and often results in severe morbidity or mortality.

Race

No racial disposition is known.

Sex

OE affects both sexes equally.

Age

Although the infection can affect all age groups, OE appears to be most prevalent in the older pediatric and young adult population.

Clinical

History

Patients with otitis externa (OE) may complain of the following:

• Otalgia ranging from mild to severe
• Hearing loss
• Ear fullness or pressure
• Tinnitus
• Fever (occasionally)
• Ear discharge
• Itch (especially in fungal infections or chronic OE)
• Severe deep pain (If experienced by a patient who is immunocompromised or diabetic, be alerted to the possibility of necrotizing OE.)

Physical

Characteristics of OE present upon physical examination may include the following:

• Pain upon palpation of the tragus (anterior to ear canal) or when applying traction to the pinna (hallmark of OE)
• Edema and redness of the ear canal (see Media file 1)
• Purulent or serous discharge in the ear canal
• Conductive hearing loss
• Cellulitis of the face or neck or lymphadenopathy of the unilateral neck (in some patients)
• Fungal OE characteristics include the following:
  • Fungal infections result in severe itch but less pain than bacterial OE.
  • A thick discharge that may be white or gray is often present.
  • Upon close examination, the discharge may have visible fungal elements or a fuzzy appearance.
• Necrotizing (malignant) OE characteristics include the following:
  • The sine qua non of necrotizing OE is pain out of proportion to clinical findings.
  • Upon close examination, granulation tissue may be present in the ear canal.

Causes

Risk factors for OE include swimming (hence, the commonly used term swimmer's ear), any source of water trapped in the ear canal, trauma to the ear canal, and a hot humid environment.

• Causative organisms for OE: These are usually Pseudomonas species, S aureus, or other gram-negative organisms.
• Fungal OE
  • Fungal OE may result from overtreatment of the ear canal with topical antibiotics, or it occasionally may present de novo from moisture trapped in the ear canal.
  • The most common organisms involved with fungal OE are Candida and Aspergillus species; however, many others have been isolated.
• Chronic OE
  • Chronic OE is a fairly common condition that may be the result of incomplete treatment of acute OE.²
  • However, chronic OE more often is caused by overmanipulation of the ear canal due to cleaning and scratching.
  • This results in a low-grade inflammatory response that further causes itching of the skin.
  • Eventually the skin thickens, and canal stenosis may occur.
• Necrotizing OE: Necrotizing OE occurs in patients who are immunocompromised and represents a true osteomyelitis of the temporal bone.

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