Necrotising Otitis Externa

• Necrotising otitis externa (NOE) is an invasive external-ear infection that can spread into the skull base and cause osteomyelitis, cranial neuropathy and intracranial complications. The older term malignant otitis externa does not denote malignancy.

• Suspect NOE in persistent otitis externa with deep or nocturnal pain, particularly with diabetes, frailty or impaired immunity. Granulation at the cartilage-bone junction, exposed bone, trismus or a cranial nerve deficit suggests invasive disease.

• Deep tissue culture, histology and skull-base CT/MRI are required urgently. Normal inflammatory markers or an early CT without erosion do not exclude disease. ^{NHS Lothian 2026}

• Systemic antipseudomonal therapy, usually for at least 6 weeks and directed by deep cultures, is the treatment; topical drops alone are inadequate. ^{ENT UK NOE}

Fissures of Santorini and a persistent foramen of Huschke provide routes of spread from the canal to the parotid and TMJ.