Makindo Medical Notes

⚠️ Necrotizing external otitis should be suspected when patients with diabetes mellitus or other immunocompromised states present with persistent, severe external otitis, especially with nocturnal pain.
🔥 Malignant otitis externa indicates extension to osteomyelitis of the temporal bone – this is a surgical emergency requiring urgent ENT referral, admission for IV antibiotics, and possible surgery.

About

• 🦠 Infection of the external auditory canal (EAC), commonly referred to as “swimmer’s ear”.
• 🌡️ Common in hot, humid climates, but severe cases occur in immunocompromised patients (especially diabetics).
• 💀 Malignant otitis externa = infection spreading to the temporal bone → osteomyelitis with risk of cranial nerve involvement.

Microbiology

• Pseudomonas aeruginosa – most common and aggressive pathogen 🧫.
• Staphylococcus aureus, S. epidermidis.
• Streptococcus pneumoniae.
• Occasionally Gram negatives and fungi (e.g. Aspergillus, Candida).

Aetiology & Risk Factors

• 🏊 Swimming in chlorinated or contaminated water (high halogen concentration).
• 🧴 Minor trauma from cotton buds, hearing aids, or scratching the EAC.
• 🧴 Underlying skin conditions (eczema, psoriasis).
• ⚠️ Diabetes mellitus – microvascular disease + pseudomonal vasculitis → poor perfusion and impaired healing.
• Severe spread: via fissures of Santorini to temporal bone → osteitis, mastoid involvement, petrous apex spread.

Clinical Features

• 🎯 Localised: Severe otalgia (often worse at night), itching, erythema, and otorrhoea.
• 🔎 Tenderness over tragus/pinna, oedema, and canal debris.
• 🚨 Malignant form:
  • Granulation tissue at the bone–cartilage junction (classic sign).
  • Facial nerve palsy (CN VII) ± other cranial neuropathies if advanced.
  • Risk of skull base osteomyelitis.

Investigations

• 🧪 Baseline: FBC, U&E, LFTs, glucose, calcium, ALP, CRP.
• 📸 Imaging:
  • CT temporal bone → bony erosion.
  • Technetium-99m bone scan → detects osteomyelitis.
  • Gallium-67 scintigraphy → helpful for monitoring treatment response.
• 🧫 Ear swab/culture to guide antibiotics.

Management

• 🧴 Simple cases:
  • Keep ear dry, no cotton buds/hearing aids during infection.
  • Topical antibiotic + steroid drops (e.g. ciprofloxacin/dexamethasone).
  • Ear wick insertion if canal is swollen/occluded.
• ⚠️ Malignant otitis externa:
  • Urgent ENT admission.
  • IV antibiotics active against Pseudomonas (e.g. ciprofloxacin, piperacillin–tazobactam, ± aminoglycosides).
  • Correction of underlying immunosuppression (e.g. optimise diabetes).
  • Local debridement; surgery only if refractory or complications (abscess, osteomyelitis progression).

Complications

• Facial nerve palsy.
• Extension to skull base → cranial neuropathies (IX, X, XI).
• Intracranial spread (abscess, meningitis).

🧾 Clinical Case – Malignant Otitis Externa

A 70-year-old man with poorly controlled type 2 diabetes presents with severe ear pain, foul-smelling discharge, and hearing loss. Examination reveals a swollen, tender external auditory canal with granulation tissue at the floor of the canal. He also reports new-onset facial weakness. CT temporal bone shows extension into the skull base. 👉 Diagnosis: Malignant otitis externa caused by Pseudomonas aeruginosa. 👉 Management: prolonged IV antipseudomonal antibiotics (e.g. ceftazidime), strict glycaemic control, and ENT referral for monitoring of cranial nerve involvement.