The diagnostic criteria of malignant external otitis.

The diagnostic criteria of malignant external otitis (MEO) have been reviewed. They were divided into two categories: obligatory and occasional. The obligatory criteria are: pain, edema, exudate, granulations, microabscess (when operated), positive bone scan or failure of local treatment often more than 1 week, and possibly pseudomonas in culture. The occasional criteria are diabetes, cranial nerve involvement, positive radiograph, debilitating condition and old age. All of the obligatory criteria must be present in order to establish the diagnosis. The presence of occasional criteria alone does not establish it. The importance of Tc99 scan in detecting osteomyelitis is stressed. When bone scan is not available, a trial of 1-3 weeks of local treatment is suggested. Failure to respond to such treatment may assist in making the diagnosis of MEO.