January 6, 2010

Malignant Otitis Externa

An Axial CT image of an 82-year-old diabetic man shows marked thickening of the right pinna (arrowhead) and external auditory canal (arrows) without extension to the skull base or evidence of mastoiditis.

Facts: Malignant Otitis Externa
  • Severe infection of the external auditory canal (EAC) and skull base
  • Elderly diabetics and immunocompromised patients
  • Most common organism = P. aeruginosa
  • Extension into deep structures or chronic osteomyelitis may occur without signs on local examination
  • Potential complications: osteomyelitis of the temporomandibular joint, sigmoid sinus thrombosis, meningitis, optic neuritis
  • Biopsy usually required to exclude carcinoma
  1. Stage 1 = confined to EAC and/or facial nerve paralysis
  2. Stage 2 = osteitis of the skull base and/or multiple cranial nerve involvement
  3. Stage 3 = meninges or brain involvement
  • CT commonly used to define location, extent of disease.
  • MRI may complement CT in cases with cranial nerve, brain involvement
  • Imaging monitoring of diseases may be done with bone scan and/or gallium scan
Okpala NCE, Siraj QH, Nilssen E, Pringle M. Radiological and radionuclide investigation of malignant otitis externa. J Laryngol Otol 2005;119:71-75.

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