An emergency medicine-focused review of malignant otitis externa

Malignant otitis externa (MOE) is a progressive infection of the external auditory canal (EAC). This disease is rare but has severe morbidity and mortality.

This narrative review provides an overview of malignant otitis externa for emergency clinicians.

MOE is an invasive external ear infection that spreads to the temporal bone and can further progress to affect intracranial structures. Complications of advanced MOE include cranial nerve involvement, most commonly the facial nerve, and intracranial infections such as abscess and meningitis. The most common causative agent of MOE is Pseudomonas aeruginosa, but others include methicillin-resistant Staphylococcus aureus and fungi. Major risk factors for MOE include diabetes mellitus, immunosuppression, and advanced age. Red flags for MOE include severe otalgia (pain out of proportion to exam) or severe otorrhea, neurologic deficits (especially facial nerve involvement), previously diagnosed otitis externa not responsive to therapy, and patients with major risk factors for MOE. Examination may show purulent otorrhea or granulation tissue in the EAC, and culture of EAC drainage should be performed. Diagnosis is aided by computed tomography (CT) with intravenous contrast, which may demonstrate bony destruction of the temporal bone or skull base. When suspecting MOE, early consultation with an otolaryngologist is recommended and antibiotics with pseudomonal coverage are needed. Most patients with MOE will require admission to the hospital.

MOE is a rare, yet deadly diagnosis that must be suspected when patients with immunocompromise, diabetes, or advanced age present with severe otalgia. Rapid diagnosis and treatment may prevent complications and improve outcomes.