Disorders of the External Ear and External Canal

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Disorders of the External Ear and External Canal

Otology/Audiology
Author Credentials 

Kathryn Y. Noonan, MD
Neurotology Fellow 
House Clinic 
University of California Los Angeles 
Los Angeles, CA 

Module Summary

This module reviews the diagnosis and management of external ear disorders. External ear disorders are extremely common and most frequently bacterial in etiology, but may arise from a fungal or viral source.  They are often associated with anatomic abnormalities, water exposure, local ear trauma, or underlying dermatologic or immune disorders.  Treatment involves careful ear debridement and topical therapy.  Unusual or resistant infections should be cultured. Surgery is rarely indicated. 

Module Learning Objectives 
  1. Summarize the differential diagnosis of external ear conditions.
  2. Use history and physical exam findings to differentiate external ear pathology.
  3. Integrate history, physical exam findings, and knowledgeable about. common pathogens to choose adequate empiric antibiotic therapy.
  4. Distinguish patients with non-infections pathology. 
  5. Identify underlying risk factor and formulate appropriate management strategies.

 

Embryology

Learning Objectives 
  1. Describe the embryologic origins and development of the external ear including the ectodermal branchial groove and the six hillocks. 
  2. Explain the canalization of the external ear canal and continued development after birth.

 

References 
  1. Nishimura Y, Kumoi T. The embryologic development of the human external auditory meatus. Preliminary report. Acta Otolaryngol. 1992;112:496–503. 
  2. Kelly KE, Mohs DC. The external auditory canal. Anatomy and physiology. Otolaryngol Clin North Am. 1996 Oct;29(5):725–39. 
  3. Anson BJ, Donaldson JA Surgical Anatomy of the Temporal bone, 3rd edition. Philadelphia, PA: WB Saunders 1981:28

 

Anatomy

Learning Objectives 
  1. Describe the shape and composition of the external canal including the bony and cartilaginous portions.
  2. Explain the function and location of adnexal structures including hair cells, sebaceous and apocrine glands.
  3. Summarize how external ear anatomy contributes to the self-protecting and self-cleaning qualities of the canal.

 

References 
  1. Gukya. AJ. Schuknecht, HF. Anatomy of the Temporal Bone with Surgical Implications, 3rd ed. New York: Informa Healthcare USA, Inc.; 2007. p. 31-39.
  2. Kelly KE, Mohs DC. The external auditory canal. Anatomy and physiology. Otolaryngol Clin North Am. 1996 Oct;29(5):725–39. 

 

Pathogenesis

Learning Objectives 
  1. Recognize the underlying pathogenesis contributing to external ear infections including anatomic considerations, dermatologic, autoimmune, water exposure, and local trauma.
References 
  1. Noonan KY, Saunders JE. External Otologic Infections. In: Infections of the Ears, Nose, Throat, and Sinuses. Ney York: Springer; 2018. p.101-114.
  2. Kelly KE, Mohs DC. The external auditory canal. Anatomy and physiology. Otolaryngol Clin North Am. 1996 Oct;29(5):725–39. 

 

Incidence

Learning Objectives 
  • Recall that external ear infections are extremely common and are more frequent in warmer climates.
  • State the incidence of external ear infections.
    • 4-14 episodes/1000 people

 

References 
  1. Noonan KY, Saunders JE. External Otologic Infections. In: Infections of the Ears, Nose, Throat, and Sinuses. Ney York: Springer; 2018. p.101-114.

Patient Evaluation

Learning Objectives 
  1. List common presenting symptoms.
  • Pain/itching
  • Fullness
  • Hearing loss
  • Otorrhea
  1. Describe pertinent history findings.
  • Trauma (q-tip or instrumentation)
  • Water exposure
  • Diabetes, radiation, HIV/AIDS, immunosuppression
  • Dermatologic conditions
  • Hearing aids/plugs
  1. Identify common physical exam pathologies and differentiating features.
  • Bacterial and fungal infections
  • Myringitis
  • Furunculosis 
  • Ramsay-Hunt
  • Skull base osteomyelitis 
  • Relapsing polychondritis 
  • Cholesteatoma
  • Middle ear infection
  • Keratosis obturans
  • Medial third stenosis 
  • Psoriasis, seborrheic keratosis 
  • Malignancy
References 
  1. Noonan KY, Saunders JE. External Otologic Infections. In: Infections of the Ears, Nose, Throat, and Sinuses. Ney York: Springer; 2018. p.101-114.
  2. Linstrom CJ, Lucente FE. Diseases of the External Ear. In: Head & Neck Surgery—Otolaryngology. Vol. 2. 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2014: p. 2333-2357

Imaging

Learning Objectives 
  1. Justify when imaging is indicated and select appropriate imaging modality.
  • Rarely indicated unless skull base osteomyelitis, complications beyond the external canal, or neoplasm is suspected.

 

References 
  1. Linstrom CJ, Lucente FE. Diseases of the External Ear. In: Head & Neck Surgery—Otolaryngology. Vol. 2. 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2014: p. 2333-2357

Pathology

Learning Objectives 
  1. Create a differential diagnosis of external ear disorders including infectious (bacterial, viral, and fungal), dermatologic, autoimmune, neoplasms, and trauma.
  2. Classify acute, subacute, and chronic infections.
  3. List the common pathologic organisms involved in external infections and how they vary between acute and chronic otitis externa.
  • Acute
    • Staphylococcus aureus
    • Pseudomonas aeruginosa
  • Chronic
    • Staphylococcus aureus
    • Pseudomonas aeruginosa
    • Corynebacterium
    • Escherichia coli
    • Enterobacter
    • Proteus mirabilis
References 
  1. Saunders JE, Raju RP, Boone J, Berryhill W. Current bacteriology of suppurative otitis: resistant patterns and outcomes analysis. Otol Neurotol. 2009 Apr;30(3):339–43. 
  2. Crowson MG, Callahan K, Saunders JE. Review of Otorrhea Microbiology: Is There a Pathogenic Role of Corynebacter? Otol & Neurotol. 2015;36(2):244–9. 
  3. Noonan KY, Saunders JE. External Otologic Infections. In: Infections of the Ears, Nose, Throat, and Sinuses. Ney York: Springer; 2018. p.101-114.

Treatment

Learning Objectives 
  1. Explain the proper management of otitis externa including aural toilet, topical antibiotic therapy, and the use of otologic wicks when necessary.
References 

See Medical Therapies section.

Medical Therapies

Learning Objectives 
  1. Distinguish situations when otologic cultures are necessary.
  • Often difficult to differentiate between fungal or bacterial on exam.
  • Indicated for all patient who have failed empiric therapy.
  1. Explain the importance of adequate debridement of canal.
  2. Give examples of when to obtain otologic cultures.
  3. Educate patients about keeping the ear dry and avoiding local trauma. 
  4. Summarize the benefits of cerumen.
  5. Recognize when otologic wick placement is appropriate.

 

References 
  1. Noonan KY, Saunders JE. External Otologic Infections. In: Infections of the Ears, Nose, Throat, and Sinuses. Ney York: Springer; 2018. p.101-114.
  2. Linstrom CJ, Lucente FE. Diseases of the External Ear. In: Head & Neck Surgery—Otolaryngology. Vol. 2. 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2014: p. 2333-2357

 

Pharmacology

Learning Objectives 
  1. Describe the empiric antibiotic choices and the value of culture-directed therapy in resistant infections.
  2. Explain the benefits of topical therapy and that it is the first choice in management of these infections.
  3. Summarize controversies in using ototoxic medications when there is a tympanic membrane perforation, or a mastoid cavity is present.

 

References 
  1. Roland PS, Stewart MG, Hannley M, Friedman R, Manolidis S, Matz G, et al. Consensus panel on role of potentially ototoxic antibiotics for topical middle ear use: Introduction, methodology, and recommendations. Otolaryngol - Head Neck Surg. 2004;130(3 SUPPL.):51–6. 
  2. Noonan KY, Saunders JE. External Otologic Infections. In: Infections of the Ears, Nose, Throat, and Sinuses. Ney York: Springer; 2018. p.101-114.

 

Surgical Therapies

Learning Objectives 
  1. Recognize medical management, antibiotics, and aural toilet are the first-line therapy choices for chronic infections.
  2. Propose situations when surgical therapy is indicated and discuss surgical approach.
  • Meatoplasty or canalplasty 

 

References 
  1. Linstrom CJ, Lucente FE. Diseases of the External Ear. In: Head & Neck Surgery—Otolaryngology. Vol. 2. 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2014: p. 2333-2357

Complications

Learning Objectives 
  1. Summarize the risk factors and presentation of skull base osteomyelitis. 
References 
  1. Hirsch BE. Otogenic skull base osteomyelitis. In Jackler RK, Brackmann DE, eds. Neurotology. 2nd ed. Chicago, IL: Mosby; 2004:1096–1106.
  2. Linstrom CJ, Lucente FE. Diseases of the External Ear. In: Head & Neck Surgery—Otolaryngology. Vol. 2. 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2014: p. 2333-2357

Review

Review Questions 
  1. What are the common pathogens involved in otologic infections?
  2. Describe the presentation, diagnosis, and management of Ramsay-Hunt syndrome and how this differs from other otologic infections. 
  3. What antibiotic (route and class of drug) is best for treating acute infections?
  4. How does management differ for chronic infections or in patients who have failed antibiotic therapy?
  5. What underlying conditions contribute to recurrent external ear infections and how are these managed? 

 

Resources 

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