eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > External Ear Diseases

External Ear, Infections

Author: Ashutosh Kacker, MD, Associate Professor of Otorhinolaryngology, Department of Otolaryngology, Weill College of Medicine of Cornell University; Consulting Staff, New York Presbyterian Hospital, New York Hospital of Queens
Contributor Information and Disclosures

Updated: Oct 10, 2007

Introduction

Background

External ear infections require otoscopic examination that must be performed in conjunction with evaluation of related structures such as the external ear and the head and neck. For example, examine the auricle for swelling, deformity, and erythema; the face for evidence of facial nerve paresis or other cranial neuropathy; and the neck for masses.

Tools

The otoscope consists of a head and a handle and is used to examine the external auditory canal (EAC), tympanic membrane, and middle ear. A magnifying lens enhances the clinician's view. One of 2 heads for the otoscope may be used. A diagnostic head is fixed to the otoscope, which does not allow use of microinstruments through the scope, while a working or operating head has a magnifying lens that can slide to the side, enabling passage of microinstruments through the speculum into the EAC and middle ear. A pneumatic attachment on the diagnostic head allows for assessment of tympanic membrane motion by generating positive pressure in the external canal, causing the tympanic membrane to deflect medially. When pressure is released, the tympanic membrane expands laterally. This technique is an important tool in the diagnosis of middle ear effusions, vascular lesions, and inner ear fistulas.

Technique

To best view the tympanic membrane in an adult, retract the auricle posteriorly and superiorly to straighten the EAC. In a child, pull the auricle posteriorly. Remove any debris or cerumen to allow for an adequate examination. Examine the external canal for masses, skin changes, and otorrhea; then, examine all parts of the tympanic membrane (eg, pars tensa, pars flaccida). Next, ascertain the motion of the tympanic membrane by pneumatic otoscopy. Lastly, attempt a thorough examination of the middle ear contents through the tympanic membrane, although this examination may be limited by the opacity of the tympanic membrane itself.

Pathophysiology

Anatomy

The external ear consists of the auricle and the EAC. The auricle is composed of elastic cartilage with the overlying skin attached directly to the perichondrium. The EAC has a cartilaginous framework in its outer third, while its inner two thirds is bony. The skin over the cartilaginous canal is thicker than that over the bony canal and contains apopilosebaceous units, which produce cerumen. Apopilosebaceous units are composed of both apocrine and eccrine glands that secrete their products around the base of a hair follicle. The EAC is related to the mandibular fossa anteriorly, mastoid air cells posteriorly, middle cranial fossa superiorly, and parotid gland inferiorly.

Glandular secretions from the apopilosebaceous unit combine with sloughed squamous epithelium (cerumen) to coat the external ear canal and maintain an acidic pH. This cerumen coat migrates from the isthmus of the external canal to the lateral part of the canal. Use of cotton swabs and excessive cleaning of the ear canal can disrupt this protective coating, leading to external ear infection.

Disorders of the EAC include otitis externa, otomycosis (fungal otitis externa), and eczematoid (psoriatic otitis externa). Otitis externa is a dermatitis most often caused by a bacterial pathogen, commonly a pseudomonal or staphylococcal species.

Otomycosis is most commonly due to infection with an Aspergillus species. Pseudomonal infection produces green or yellow purulent otorrhea. Aspergillus otomycosis appears as a fine white mat topped by black spheres. In addition to otorrhea, erythema and edema of the EAC are common. In severe cases, soft tissue stenosis may be present. Extension of the infection from the EAC may manifest as cellulitic skin changes involving the concha of the auricle and the tragus. In most cases, treatment consists of acidification of the ear canal with drops, with or without topical antibiotics, although systemic antibiotics may be necessary as well.

Eczematoid is somewhat different in that it is not due to an infectious pathogen. This condition often manifests as a moist, white, granular otorrhea on an erythematous base. Eczematoid often responds to topical steroid drops but may be chronic or recurrent.

Embryology

Auricle: The auricle begins to form during the sixth week of gestation by a consolidation of portions of the mesoderm of the first and second branchial arches, giving rise to the His hillocks. The first 3 hillocks are derived from the first arch, and the second 3 are from the second arch. The auricle reaches adult shape by the twentieth week of gestation, but the adult size is not reached until age 9 years.

EAC: The EAC begins to form during the eighth week of gestation, when the surface ectoderm of the first pharyngeal groove thickens and grows toward the middle ear. This core of tissue begins to resorb by the 21 weeks' gestation to form a channel that is complete by 28 weeks' gestation. The canal reaches adult size by age 9 years and ossifies completely by age 3 years.

Frequency

United States

Otitis externa is a common disorder, but frequency, sex, and age predilection is unknown.

Clinical

History

Usually a history of preceding ear trauma in the form of forceful ear cleaning, use of cotton swabs, or water in the ear canal is present.

Severe throbbing pain with ear discharge follows, which can then lead to a hearing loss due to occlusion of the ear canal.

Physical

Pseudomonal infection produces purulent otorrhea that may be green or yellow, while Aspergillus otomycosis looks like a fine white mat topped by black spheres. In addition to otorrhea, erythema and edema of the EAC is common. In severe cases, soft tissue stenosis may be present. Extension of the infection from the EAC may manifest as cellulitic skin changes involving the concha of the auricle and the tragus.

Causes

Common predisposing causes are swimming, forceful cleaning of the ear, and trauma.

More on External Ear, Infections

Overview: External Ear, Infections
Differential Diagnoses & Workup: External Ear, Infections
Treatment & Medication: External Ear, Infections
Follow-up: External Ear, Infections
References
[ CLOSE WINDOW ]

References

  1. Brook I. Treatment of otitis externa in children. Paediatr Drugs. Oct-Dec 1999;1(4):283-9. [Medline].

  2. Mirza N. Otitis externa. Management in the primary care office. Postgrad Med. May 1996;99(5):153-4, 157-8. [Medline].

  3. Morden NE, Berke EM. Topical fluoroquinolones for eye and ear. Am Fam Physician. Oct 15 2000;62(8):1870-6. [Medline].

  4. Selesnick SH. Otitis externa: management of the recalcitrant case. Am J Otol. May 1994;15(3):408-12. [Medline].

  5. Tierney MR, Baker AS. Infections of the head and neck in diabetes mellitus. Infect Dis Clin North Am. Mar 1995;9(1):195-216. [Medline].

[ CLOSE WINDOW ]

Further Reading

[ CLOSE WINDOW ]

Keywords

external ear infections, ear infections, infections of the external ear, otitis externa, swimmer ear, swimmer's ear, malignant otitis externa, ear furuncle, external auditory canal, EAC, otomycosis, fungal otitis externa, eczematoid, psoriatic otitis externa, otorrhea, herpes zoster oticus

[ CLOSE WINDOW ]

Contributor Information and Disclosures

Author

Ashutosh Kacker, MD, Associate Professor of Otorhinolaryngology, Department of Otolaryngology, Weill College of Medicine of Cornell University; Consulting Staff, New York Presbyterian Hospital, New York Hospital of Queens
Ashutosh Kacker, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American College of Surgeons, American Rhinologic Society, and Triological Society
Disclosure: Nothing to disclose.

Medical Editor

Jack A Shohet, MD, Associate Clinical Professor, Department of Otolaryngology-Head and Neck Surgery, University of California at Irvine Medical Center
Jack A Shohet, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American Laryngological Rhinological and Otological Society, American Medical Association, American Society for Laser Medicine and Surgery, American Tinnitus Association, and California Medical Association
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Gerard J Gianoli, MD, Clinical Associate Professor, Department of Otolaryngology-Head and Neck Surgery, Tulane University School of Medicine
Gerard J Gianoli, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American College of Surgeons, American Neurotology Society, American Otological Society, Louisiana State Medical Society, and Triological Society
Disclosure: Nothing to disclose.

CME Editor

Christopher L Slack, MD, Otolaryngology-Facial Plastic Surgery, Private Practice, Associated Coastal ENT; Medical Director, Treasure Coast Sleep Disorders
Christopher L Slack, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, and American Medical Association
Disclosure: Nothing to disclose.

Chief Editor

Arlen D Meyers, MD, MBA, Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine
Arlen D Meyers, MD, MBA is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, and American Head and Neck Society
Disclosure: UST Grant/research funds Consulting

 
 
HONcode

We subscribe to the
HONcode principles of the
Health On the Net Foundation

All material on this website is protected by copyright, Copyright© 1994- by Medscape.
This website also contains material copyrighted by 3rd parties.

DISCLAIMER: The content of this Website is not influenced by sponsors. The site is designed primarily for use by qualified physicians and other medical professionals. The information contained herein should NOT be used as a substitute for the advice of an appropriately qualified and licensed physician or other health care provider. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please check with a physician if you suspect you are ill.