Malignant External Otitis
(Skull Base Osteomyelitis; Necrotizing Otitis Externa)
Malignant external otitis is infection of the external ear that has spread to the skull bone (temporal bone) containing the ear canal, the middle ear, and the inner ear.
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 notcancerous (malignant).
The diagnosis 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.
Meticulous control of diabetes is essential.
Although surgery usually is not necessary, repeated cleanings of 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.
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