Malignant otitis externa

Background

Ear anatomy
  • Life-threatening infection of external ear/canal, soft tissue, +/- spread to skull base
  • Diabetes and immunosuppression are main risk factors
  • Pseudomonas causes >90% of cases
  • Begins as simple otitis externa

Clinical Features

Adults

  • Otitis externa that has not resolved despite 2-3wks of topical antibiotics
  • Otalgia often out of proportion for routine otitis externa
  • Edema of external auditory canal
  • Granulation tissue often seen in the ear canal floor
  • Facial nerve often first CN involved[1]
  • CN IX, X, or XI involvement
  • Trismus

Pediatrics

  • More rapidly progressive than in adults
  • TM, middle ear, and facial nerve more likely to be affected

Differential Diagnosis

Ear Diagnoses

External

Internal

Inner/vestibular

Evaluation

Malignant external otitis. Axial CT scan in bone window demonstrates destruction of mastoid segment of petrous bone. There were also subtle cortical destructions visible in tympanic bone.
  • Imaging[2]
    • Most authors support CT initially, but CT fails to diagnose early osteomyelitis since 30% bone destruction needed for detection
    • MRI more sensitive for intracranial complications
  • Labs
    • WBC usually normal or slightly elevated
    • Left shift uncommon
    • Elevated ESR and CRP
      • Differentiates from MOE from acute external otitis or malignancy
      • However, not required for diagnosis[3]

Management

Adults

Peds

Disposition

  • Contact ENT for disposition decision; early infection may be managed as outpatient

Complications

See Also

References

  1. ↑ Pfaff JA, Moore GP: Otolaryngology, in Marx JA, Hockberger RS, Walls RM, et al (eds): Rosen’s Emergency Medicine: Concepts and Clinical Practice, ed 8. St. Louis, Mosby, Inc., 2014, Ch 72.
  2. ↑ Nussenbaum B et Al. Malignant Otitis Externa Workup. Medscape, Jul 14 2015. http://emedicine.medscape.com/article/845525-workup#c4
  3. ↑ Hosmer, K: Ear Disorders, in Tintinalli JE, Stapczynski JS, Ma OJ, Yealy DM, Meckler GD, Cline DM (eds): Emergency Medicine, A Comprehensive Study Guide, ed 8. New York, McGraw-Hill, 2016, Ch 242:p 1581-2.
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