Necrotizing Otitis Externa

Aka: Necrotizing Otitis Externa, Malignant External Otitis, Malignant Otitis Externa, Osteitis of the Skull Base, Malignant Otitis Externa due to Pseudomonas aeruginosa, Osteomyelitis of Temporal Bone

II. Risk Factors

  1. Diabetes Mellitus
  2. Elderly
  3. Immunocompromised state (e.g. Chemotherapy)
  4. Human Immunodeficiency Virus (HIV, AIDS)

III. Pathophysiology

  1. Necrotizing infection of the soft tissue of the external auditory canal
    1. Pseudomonas aeruginosa is most common causative organism (accounts for 95% of cases)
    2. Staphylococcus aureus accounts for the remaining cases
  2. Complication of Otitis Externa
    1. Infection extends into ear canal cartilage
    2. Passes to Temporal Bone via Santorini's Fissures
  3. Severe extension of external Otitis Media
    1. Mastoiditis
    2. Osteitis of Temporal Bone

IV. Symptoms: Severe Otitis Externa

  1. Severe, unrelenting Ear Pain and Headache
  2. Persistent discharge
  3. Hearing Loss
  4. Does not respond to topical medications
  5. Commonly associated with Diabetes Mellitus
  6. Fever is typically absent

V. Signs

  1. Purulent Otorrhea
  2. Tender and swollen external auditory canal
  3. Tympanic Membrane spared
  4. Granulation tissue in posterior and inferior canal and possible exposed bone
    1. Pathognomonic for necrotizing otitis
    2. Occurs at bone-cartilage junction
  5. Extra-auricular findings
    1. Cervical Lymphadenopathy
    2. Trismus (TMJ involvement)
    3. Facial Nerve Palsy or paralysis (Bell's Palsy)
      1. Associated with poor prognosis

VI. 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

VII. Imaging

  1. CT Scan or MRI of ear
    1. CT findings lag behind clinical findings (but best for bony involvement evaluation)
  2. Nuclear imaging
    1. Technetium Tc 99m medronate methylene bone scanning
    2. Gallium citrate Ga 67 scintography
      1. High sensitivity for current infection
      2. Useful for follow-up for resolution

VIII. Management

  1. Admit to hospital
  2. Anti-pseudomonal antibiotics
    1. Intravenous Antibiotic options
      1. Ciprofloxacin 400 mg IV every 8 hours (preferred)
      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. Piperacillin-Tazobactam 4.5 g IV every 6-8 hours AND Aminoglycoside (Tobramycin or Gentamicin)
    2. Oral antibiotic options (after initial IV course or for mild, early involvement)
      1. Ciprofloxacin 750 mg PO q12 hours
    3. Course
      1. Start with IV antibiotics
      2. Continue antibiotics for 4-6 weeks if bone involvement (shorter courses if not)
    4. Alternative course in a well appearing reliable patient
      1. Ceftazidime can be given IM and could be used with follow-up within 8-12 hours
      2. Hospital admission with IV antibiotics is safest course
  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 [PubMed]

IX. Complications

  1. Skull Osteomyelitis
  2. Cranial Nerve palsy
  3. Septic venous sinus thrombosis
  4. Meningitis
  5. Cerebral abscess

X. Prognosis

  1. Mortality reportedly as high as 20 to 53%

XI. 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

XII. References

  1. (2019) Sanford Guide, accessed on IOS, 11/28/2019
  2. Khoujah (2013) Crit Decis Emerg Med 27(4): 12-21
  3. Bath (1998) J Laryngol Otol 112:274-7 [PubMed]
  4. Handzel (2003) Am Fam Physician 68(2):309-12 [PubMed]
  5. Sander (2001) Am Fam Physician 63:927-42 [PubMed]
  6. Selesnick (1994) Am J Otol 15:408-12 [PubMed]

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Related Studies

Ontology: Malignant otitis externa (C0155395)

Concepts Disease or Syndrome (T047)
ICD9 380.14
ICD10 H60.2 , H60.20
SnomedCT 194206006, 94146005
Dutch maligne otitis externa, otitis; externa, Pseudomonas aeruginosa, otitis; externa, maligne, Maligne otitis externa
French Otite externe maligne
German boesartige Otitis externa, Otitis externa maligna
Italian Otite esterna maligna
Portuguese Otite externa maligna
Spanish Otitis externa maligna, otitis externa maligna (trastorno), otitis externa maligna, otitis externa por Pseudomonas aeruginosa
Japanese 悪性外耳炎, ｱｸｾｲｶﾞｲｼﾞｴﾝ
Czech Maligní infekce zevního ucha
Korean 악성 바깥귀길염
English Malignant otitis externa, unspecified ear, externa malignant otitis, malignant otitis externa, otitis externa malignant, malignant otitis externa (diagnosis), Malignant otitis externa, Otitis externa due to Pseudomonas aeruginosa, Malignant otitis externa (disorder), otitis; externa, Pseudomonas aeruginosa, otitis; externa, malignant
Hungarian Rosszindulatú otitis externa
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Malignant otitis externa due to Pseudomonas aeruginosa (C0395818)

Concepts Disease or Syndrome (T047)
SnomedCT 232230009
English Malign ext otitis Pseud aer, Malignant otitis externa due to Pseudomonas aeruginosa, Malignant otitis externa due to Pseudomonas aeruginosa (disorder)
Spanish otitis maligna externa por Pseudomonas aeruginosa (trastorno), otitis maligna externa por Pseudomonas aeruginosa
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Osteomyelitis of temporal bone (C1290171)

Concepts Disease or Syndrome (T047)
SnomedCT 109307002
English osteomyelitis of temporal bone (diagnosis), Osteomyelitis of temporal bone (disorder), Osteomyelitis of temporal bone
Spanish osteomielitis del hueso temporal (trastorno), osteomielitis del hueso temporal
Derived from the NIH UMLS (Unified Medical Language System)

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