Malignant Otitis Externa

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Definition & Etiology - Skull Base Invader

  • Aggressive, necrotizing infection of the External Auditory Canal (EAC), temporal bone, and skull base.
  • A severe osteomyelitis, typically originating from the EAC.
  • Etiology:
    • ⭐ Most common causative organism is Pseudomonas aeruginosa (>95%), especially in elderly diabetic patients.

    • Fungal (e.g., Aspergillus) in immunocompromised or after prolonged antibiotics.
  • Key Risk Factors:
    • Elderly with Diabetes Mellitus (DM) (📌 Diabetic Elderly)
    • Immunocompromised states (HIV, chemotherapy, organ transplant)
    • Local EAC trauma or prior surgery. oka

Clinical Features & Pathophysiology - Sinister Signs

  • Pathophysiology: Aggressive Pseudomonas aeruginosa infection leading to osteomyelitis of temporal bone and skull base. Typically affects elderly, diabetic, or immunocompromised individuals. Underlying vasculitis & endarteritis facilitate spread.
  • Sinister Signs (Spread Beyond EAC):
    • Severe, deep-seated, nocturnal otalgia.
    • Persistent, purulent, often foul-smelling otorrhea.
    • Cranial nerve palsies: CN VII (facial nerve) most common; later CN IX, X, XI, XII.
    • Trismus (jaw stiffness).
    • ⚠️ Advanced: Meningitis, sepsis.

⭐ Pathognomonic sign: granulation tissue at the bony-cartilaginous junction of the external auditory canal (Holman-Miller sign).

Diagnosis & Staging - Pinpointing Peril

  • Clinical Triad: Persistent otalgia (nocturnal ↑), purulent otorrhea, granulation tissue (EAC floor).
  • Key Signs: Cranial neuropathies (CN VII common) = advanced disease.
  • Investigations:
    • Biopsy: Granulation tissue (R/O malignancy).
    • Culture: P. aeruginosa (common).
    • ESR/CRP: ↑↑, monitor response.
  • Imaging:
    • CT (Temporal): Bony erosion.
    • MRI: Soft tissue, intracranial, early changes.
    • Radionuclide: Tc-99m (bone), Ga-67 (inflammation/response).

    ⭐ CT scan is superior for visualizing bony erosion, while MRI is better for assessing soft tissue extension and early changes before significant bone destruction.

  • Chandler Staging:
    • I: Soft tissue, no bone erosion.
    • II: Bone erosion (EAC).
    • III: Skull base osteomyelitis ± CN VII palsy.
    • IV: Other CN palsies / Intracranial spread.

Management & Complications - Aggressive Action

  • Core Strategy: Prolonged systemic anti-pseudomonals & meticulous local care.

    ⭐ Treatment requires prolonged (typically 6-8 weeks) systemic anti-pseudomonal antibiotics, often IV initially.

  • Medical Management:
    • IV Anti-pseudomonals (e.g., Ciprofloxacin, Ceftazidime, Piperacillin-Tazobactam) initially, transition to oral.
    • Regular aural toilet, debridement.
    • Strict glycemic control (critical in diabetics).
    • Hyperbaric Oxygen (HBO): adjunctive for refractory/severe cases.
  • Surgical Intervention (Reserved):
    • Failure of medical therapy.
    • For bone necrosis/sequestra removal.
    • Abscess drainage.
    • Diagnostic biopsy if needed.
  • Key Complications:
    • Cranial nerve palsies (CN VII most common, then IX-XII).
    • Skull base osteomyelitis; intracranial spread (meningitis, abscess).
    • High mortality if untreated/aggressive.

High‑Yield Points - ⚡ Biggest Takeaways

  • Caused by Pseudomonas aeruginosa, mainly in elderly diabetics or immunocompromised.
  • Presents with severe otalgia, otorrhea, and granulation tissue at EAC's bony-cartilaginous junction.
  • Facial nerve (CN VII) palsy is a common, ominous sign.
  • CT scan shows bony erosion; Gallium scan indicates inflammation.
  • Treatment involves prolonged systemic anti-pseudomonal antibiotics (e.g., ciprofloxacin).
  • Skull base osteomyelitis is a severe complication.
  • Biopsy essential to rule out malignancy_._

Practice Questions: Malignant Otitis Externa

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All are intracranial complications of otitis media except which of the following?

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Flashcards: Malignant Otitis Externa

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Treatment of ANOM must include IV antibiotics for a minimum of _____ days.

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Treatment of ANOM must include IV antibiotics for a minimum of _____ days.

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