Malignant external otitis occurs mainly in people with a weakened immune system and in older people with diabetes. Infection of the external ear, usually caused by the bacteria Pseudomonas, spreads into the temporal bone, causing severe, life-threatening infection. Methicillin-resistant Staphylococcus aureus (MRSA) has also been identified as a cause. Despite the name, the infection is not cancerous (malignant).
People with malignant external otitis have severe ear pain (often worse at night), a foul-smelling discharge from the ear, pus and debris in the ear canal, and usually decreased hearing. In severe cases, paralysis of nerves in the face and head may occur as the infection spreads along the base of the skull.
The diagnosis of malignant external otitis is based on CT scan results. Doctors also do a culture (a sample of the discharge is grown in a laboratory to identify the microorganisms). Often doctors need to take a small piece of tissue from the ear canal and examine it under a microscope (biopsy) to make sure that the symptoms are not caused by cancer.
Typically, malignant external otitis is treated with a 6-week course of antibiotics given by vein. However, people with a mild infection may be treated with high doses of an antibiotic such as ciprofloxacin taken by mouth. Some people may be treated in a high-pressure oxygen chamber (hyperbaric oxygen therapy). People who have extensive bone disease may require antibiotic therapy for a longer period.
Although surgery usually is not necessary, repeated cleanings and removal of dead skin and inflammatory tissue (debridement) in the ear canal in the doctor's office are necessary until the infection goes away.