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Necrotising otitis externa
Necrotising otitis externa is skull base osteomyelitis that starts in the ear canal, mainly in an older diabetic, usually from Pseudomonas aeruginosa; the sign is severe night pain with granulation tissue on the canal floor, and treatment is anti-pseudomonal antibiotics for many weeks with glucose control.
Why it matters in the exam
The exam shows an older diabetic with severe ear pain that does not respond to drops, discharge and granulation tissue on the canal floor at the bony-cartilaginous junction. Infection spreads through the fissures of Santorini in the cartilage and through the bony-cartilaginous junction to the skull base. The first and commonest nerve affected is the facial nerve (VII), at its exit at the stylomastoid foramen; then nerves IX, X and XI at the jugular foramen and XII. Nerve palsies indicate advanced disease.
Diagnosis combines the clinical picture, inflammatory markers and imaging. CT shows bone erosion and helps planning, but bone changes appear late; MRI shows soft-tissue and marrow involvement. Technetium-99 bone scanning is very sensitive but not specific; gallium-67 scanning or white-cell SPECT is used to follow response to treatment. Biopsy of the granulation tissue is needed to exclude squamous cell carcinoma of the canal, and culture — before antibiotics when possible.
Treatment: anti-pseudomonal antibiotics — high-dose oral ciprofloxacin in early disease, or IV therapy (ceftazidime, piperacillin-tazobactam or a carbapenem) in advanced disease or resistance — usually 6 to 8 weeks or more; glucose control; local cleaning. Surgery is reserved for debridement of necrotic tissue or an abscess. ESR and CRP are used for follow-up, and their fall together with less pain guides the duration of treatment. The disease can relapse after treatment stops, so clinical follow-up continues even after the pain has settled.
Key points
- Skull base osteomyelitis from the ear canal.
- Older diabetic, Pseudomonas.
- Granulation on the canal floor and night pain.
- Nerve VII is affected first.
- 6 to 8 weeks of antibiotics and ESR follow-up.
Summary table
| Aspect | Detail | Meaning |
|---|---|---|
| Who | Older diabetic or immunocompromised | High suspicion for any refractory ear pain |
| Organism | Pseudomonas aeruginosa | Anti-pseudomonal antibiotics |
| Spread | Fissures of Santorini and the bony-cartilaginous junction | To the skull base |
| First nerve | Nerve VII at the stylomastoid foramen | Sign of advanced disease |
| Imaging | CT, MRI, technetium-99 scan and gallium-67 scan | Diagnosis and follow-up |
| Treatment | 6 to 8 weeks or more, glucose control | Follow ESR and CRP |
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Sources
- Cummings Otolaryngology: Head and Neck Surgery, 7th edition (2021) — Infections of the external ear: necrotising otitis externa
- Necrotising otitis externa: a multidisciplinary consensus definition and diagnostic criteria (Hopkins et al.), 2023 — Diagnosis, imaging and treatment duration
- AAO-HNS Clinical Practice Guideline: Acute Otitis Externa, 2014 — Risk factors for necrotising disease
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.