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Necrotizing Otitis ExternaAka: Malignant External Otitis, Malignant Otitis Externa, Osteitis of the Skull Base

Risk Factors
1. Diabetes Mellitus
2. Elderly
3. Immunocompromised state
4. Human Immunodeficiency Virus (HIV)
Pathophysiology
1. Complication of Otitis Externa
  1. Infection extends into ear canal cartilage
  2. Passes to temporal bone via Santorini's Fissures
2. Pseudomonas aeruginosa infection
3. Severe extension of external Otitis Media
  1. Mastoiditis
  2. Osteitis of temporal bone
Signs and symptoms
1. Similar to Otitis Externa except
  1. Severe, unrelenting Ear Pain and Headache
  2. Persistent discharge
  3. Does not respond to topical medications
  4. Commonly associated with Diabetes Mellitus
2. Granulation tissue in posterior and inferior canal
  1. Pathognomonic for necrotizing otitis
  2. Occurs at bone-cartilage junction
3. Extra-auricular findings
  1. Cervical Lymphadenopathy
  2. Trismus (TMJ involvement)
  3. Facial Nerve Palsy or paralysis (Bell's Palsy)
    1. Associated with poor prognosis
Prognosis
1. Mortality reportedly as high as 20 to 53%
Labs
1. Complete Blood Count
2. Culture ear discharge
3. Erythrocyte Sedimentation Rate (ESR) markedly elevated
4. Serum Glucose
5. Serum Creatinine
6. Histology of granulation tissue excised from canal
Radiology
1. CT Scan or MRI of ear
  1. CT findings lag behind clinical findings
2. Technetium Tc 99m medronate methylene bone scanning
3. Gallium citrate Ga 67 scintography
  1. High sensitivity for current infection
  2. Useful for follow-up for resolution
Prevention
1. Avoid use of cotton swabs in ear and other canal trauma
2. Use caution when irrigating ear of high risk patients
3. Treat eczema of ear canal and other pruritic dermatitis
Management
1. Admit to hospital
2. Anti-pseudomonal antibiotics
  1. Intravenous Antibiotic options
    1. Ciprofloxacin 400 mg IV q12 hours
    2. Imipenem 0.5 mg IV q6 hours
    3. Meropenem 1.0 grams IV q8 hours
    4. Ceftazidime 2.0 grams IV q8 hours
    5. Cefepime 2.0 grams IV q12 hours
    6. Gentamicin 1 to 1.66 mg/kg IV or IM/IV with
      1. Ticarcillin or
      2. Piperacillin
    7. Timentin 3.0 grams IV q4 hours
  2. Oral antibiotic options (after initial IV course)
    1. Ciprofloxacin 750 mg PO q12 hours
  3. Course
    1. Start with IV antibiotics
    2. Continue antibiotics for 4-8 weeks
3. Consult Otolaryngology (ENT)
  1. Surgical debridement may be required
4. Clean ear canals meticulously on a daily basis
  1. Clean and debride canal
  2. Apply topical antibiotic agents
5. Other modalities to consider
  1. Hyperbaric oxygen chamber
  2. Davis (1992) Arch Otolaryngol Head Neck Surg 118:89
References

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This page was written by Scott Moses, MD. This page was last revised before 5/10/08, prior to consistent tracking of revision date. This page was last published on 5/16/2008. Please send comments and questions to the editor. Contact information may be found on the page About the Family Practice Notebook. These pages are best viewed with Microsoft Internet Explorer 6.0.