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.