[Malignant external otitis. When and which imaging].

Malignant external otitis (MEO) is a severe infection of the external auditory canal (EAC), most often caused by Pseudomonas aeruginosa, although a few cases are caused by an Aspergillus (4). Mortality remains high (20%) in spite of an early general antibiotic treatment. This infection of the soft tissue of the EAC causes cellulitis, chondritis and osteomyelitis, and there are risks of diffusion into the base of the skull. Our work is aimed at placing computed tomography and magnetic resonance imaging into the context of exploration of this infection, in relation to radionuclide scanning, owing to our experience with 10 patients. Imaging appreciates the anatomical extension of the infection beyond the EAC and towards the base of the skull and the infratemporal fossa, this being a key element for prognosis. It assesses the efficiency and duration of treatment, although the criteria of healing are still difficult to appreciate and late recurrence is frequent. Exceptionally, it is useful for diagnosis in some particular clinical forms.