Malignant otitis externa

Last updated: November 2, 2022

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Malignant otitis externa (MOE) is a severe variant of acute otitis externa (AOE) in which necrotizing inflammation of the external auditory canal (EAC) develops. MOE is usually caused by Pseudomonas aeruginosa and most frequently affects older adults and individuals with diabetes and/or immunosuppression. Clinical features of MOE include severe pain, an erythematous and edematous EAC, and otorrhea; granulation tissue is visible on otoscopy. Because of the rapid spread of infection, patients may have signs of complications (e.g., cranial nerve palsies secondary to osteomyelitis of the skull base) on initial presentation. Imaging and laboratory studies are recommended to confirm the diagnosis. Treatment is with IV antibiotics; surgery may be required for debridement or abscess drainage. The prognosis with treatment is good, with overall mortality < 10%.

All patients require laboratory studies and imaging.

Laboratory studies [1][2]

Imaging [2]

More than one imaging modality is often required.

  • Modalities [6]
    • CT head with IV contrast: preferred initial study
    • MRI head: best modality for detecting soft tissue extension and intracranial abnormalities
    • Radionuclide scans: may be useful for early detection [6][7]
    • PET/CT scan: helpful for diagnosis and monitoring treatment response
  • Findings

A negative CT scan does not exclude early MOE, as changes may not be evident until one-third of bone mineral is eroded. [8]

Surgical biopsy [2]

Consider if there is diagnostic uncertainty or insufficient response to treatment.

Treatment involves early empiric antibiotic therapy and the control of risk factors for MOE (e.g., diabetes or immunosuppression), in consultation with an otolaryngologist. [1][2]

Antibiotic therapy [2][3][8]

Surgery [1][2]

  • May be required in select cases, e.g., abscess drainage or debridement of bony sequestra
  • Send any surgical specimens for pathology and microbiological testing.

Patients unresponsive to antibiotic therapy may require a surgical biopsy to rule out fungal etiology or malignancy. [2]

Disposition [10]

  • Urgent otolaryngology consult
  • Patients typically require initial hospitalization followed by outpatient care for prolonged IV antibiotics.

Monitoring of treatment response [1][2]

We list the most important complications. The selection is not exhaustive.

  • Overall mortality: < 10% [2]
  • Rates may be higher in patients aged over 80 years or with significant comorbidities. [2]

MOE is a severe infection that can be lethal without prompt treatment. Death is most commonly caused by intracranial complications. [8]

  1. Rosenfeld RM, Schwartz SR, Cannon CR, et al. Clinical Practice Guideline: Acute Otitis Externa. Otolaryngol Head Neck Surg. 2014; 150 (1_suppl): p.S1-S24. doi: 10.1177/0194599813517083 . | Open in Read by QxMD
  2. Durand ML. Infections of the Ears, Nose, Throat, and Sinuses. Springer International Publishing ; 2018 : p. 115-131
  3. Khan HA. Necrotising Otitis Externa: A Review of Imaging Modalities. Cureus.. 2021 . doi: 10.7759/cureus.20675 . | Open in Read by QxMD
  4. Sturm JJ, Stern Shavit S, Lalwani AK. What is the Best Test for Diagnosis and Monitoring Treatment Response in Malignant Otitis Externa?. Laryngoscope. 2020; 130 (11): p.2516-2517. doi: 10.1002/lary.28609 . | Open in Read by QxMD
  5. Handzel O, Halperin D. Necrotizing (malignant) external otitis. Am Fam Physician. 2003; 68 (2): p.309-12.
  6. Carfrae MJ, Kesser BW. Malignant Otitis Externa. Otolaryngol Clin North Am. 2008; 41 (3): p.537-549. doi: 10.1016/j.otc.2008.01.004 . | Open in Read by QxMD
  7. Byun YJ, Patel J, Nguyen SA, Lambert PR. Necrotizing Otitis Externa: A Systematic Review and Analysis of Changing Trends. Otol Neurotol. 2020; 41 (8): p.1004-1011. doi: 10.1097/mao.0000000000002723 . | Open in Read by QxMD
  8. Hobson CE, Moy JD, Byers KE, Raz Y, Hirsch BE, McCall AA. Malignant Otitis Externa: Evolving Pathogens and Implications for Diagnosis and Treatment. Otolaryngol Head Neck Surg. 2014; 151 (1): p.112-116. doi: 10.1177/0194599814528301 . | Open in Read by QxMD
  9. Klein JO. Otitis Externa, Otitis Media, and Mastoiditis. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 2015 : p.767-773.e1. doi: 10.1016/b978-1-4557-4801-3.00062-x . | Open in Read by QxMD
  10. Walls R, Hockberger R, Gausche-Hill M, Erickson TB, Wilcox SR. Rosen's Emergency Medicine 10th edition- Concepts and Clinical Practice E-Book. Elsevier Health Sciences ; 2022

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