AKT · ENT/Ear & hearinglow yield

Necrotising (malignant) otitis externa

Invasive Pseudomonas osteomyelitis of the skull base

Overview

An aggressive, invasive infection (almost always Pseudomonas aeruginosa) spreading from the ear canal to the temporal bone/skull base — effectively a skull-base osteomyelitis. It occurs in DIABETICS and the immunocompromised, and is the must-not-miss behind "otitis externa" with severe pain, granulation tissue, and cranial nerve (especially FACIAL) palsy.

Recognise

Severe, deep, unremitting ear pain (often worse than the otoscopic findings) and discharge in a DIABETIC/immunocompromised patient
GRANULATION TISSUE at the bony-cartilaginous junction of the canal floor — the cardinal sign
Cranial nerve palsies as it spreads — facial nerve (VII) first, then IX/X/XI at the jugular foramen; raised ESR/CRP

Red flags

Any cranial nerve palsy, severe pain out of proportion, or failure of "otitis externa" to settle in a diabetic → emergency ENT, imaging, IV antipseudomonal therapy

Differentials & how to tell them apart

Simple otitis externasettles with topical treatment, no granulation/cranial-nerve signs or skull-base pain — necrotising OE is the diabetic non-resolving emergency

Cholesteatomaattic squamous debris + conductive loss; can also cause facial palsy — imaging/otoscopy differ

Skull-base tumourbiopsy of granulation tissue excludes malignancy

Investigations

Raised ESR/CRP; ear swab/biopsy of granulation tissue (Pseudomonas; biopsy also excludes malignancy); CT (bony erosion) and MRI/nuclear imaging to map skull-base involvement. Urgent ENT.

Management

Urgent ENT + prolonged systemic anti-pseudomonal antibiotics (ciprofloxacin) + glycaemic control

1Admit/urgent ENT; raised inflammatory markers + imaging + biopsy of granulation tissue. Prolonged systemic anti-pseudomonal antibiotics (e.g. ciprofloxacin), optimise diabetes/immunosuppression.Gate: In a DIABETIC with severe ear pain, granulation tissue, or a FACIAL NERVE palsy, this is necrotising OE (skull-base osteomyelitis), NOT simple otitis externa → systemic antibiotics + imaging + ENT, never just topical drops
2Image to map skull-base/intracranial spread; surgical debridement for sequestrum; long-course antibiotics with inflammatory-marker monitoring.

Prolonged systemic antipseudomonal antibiotic (ciprofloxacin) — first-line; often weeks (IV then oral), guided by ENT/microbiology

Glycaemic control + correct immunosuppression — essential adjunct

Surgical debridement — for extensive disease/sequestrum

Key points

Diabetic + disproportionate ear pain + granulation + facial palsy = necrotising OE. It is osteomyelitis of the skull base, so it needs weeks of systemic antipseudomonal therapy, not drops. ESR/CRP track response.

Monitor & prognosis

ESR/CRP, cranial nerves, glycaemic control, imaging resolution.

Serious; good with early prolonged treatment, poor with skull-base/intracranial spread.

Source: NICE CKS Otitis externa; ENT UK