Necrotizing (malignant) external otitis.
Necrotizing (malignant) external otitis, an infection involving the temporal and adjacent bones, is a relatively rare complication of external otitis. It occurs primarily in immunocompromised persons, especially older persons with diabetes mellitus, and is often initiated by self-inflicted or iatrogenic trauma to the external auditory canal. The most frequent pathogen is Pseudomonas aeruginosa. Patients with necrotizing external otitis complain of severe otalgia that worsens at night, and otorrhea. Clinical findings include granulation tissue in the external auditory canal, especially at the bone-cartilage junction. Facial and other cranial nerve palsies indicate a poor prognosis; intracranial complications are the most frequent cause of death. Diagnosis requires culture of ear secretions and pathologic examination of granulation tissue from the infection site. Imaging studies may include computed tomographic scanning, technetium Tc 99m medronate bone scanning, and gallium citrate Ga 67 scintigraphy. Treatment includes correction of immunosuppression (when possible), local treatment of the auditory canal, long-term systemic antibiotic therapy and, in selected patients, surgery. Family physicians and others who provide medical care for immunocompromised patients should be alert to the possibility of necrotizing external otitis in patients who complain of otalgia, particularly if they have diabetes mellitus and external otitis that has been refractory to standard therapy. Susceptible patients should be educated to avoid manipulation of the ear canal (i.e., they should not use cotton swabs to clean their ears) and to minimize exposure of the ear canal to water with a high chloride concentration. Appropriate patients should be referred to an otolaryngologist.