Necrotizing otitis externa

Necrotizing otitis externa is also known as 'malignant otitis externa'. It is not that the condition may become malignant, but because of the occasional fatal outcome. This typically occurs in elderly patient who is diabetic or is immunocom-promised for other reasons. There is usually a long history of ear discharge and otalgia is frequently present and pronounced. The causative organism is Pseudomonas pyocyanea. The clinical features of 'necrotizing otitis externa' are often misleading and deceptive in the early phase of the disease. However, the response to standard treatment is poor and the condition may suddenly deteriorate. Ear examination often shows exuberant granulation tissue. A biopsy should be taken for microbiological work-up and for histological examination to exclude malignancy. Infection and the necrotizing process may spread to involved the temporal bone causing osteomyelitis. The first indication is often facial nerve palsy. In advanced disease, the jugular foramen may also be affected by osteomyelitis resulting in ninth, tenth and eleventh cranial nerves palsies. Thrombosis of the internal jugular vein and retrograde cavernous sinus thrombosis may also occur.

If the condition is suspected, the patient should be treated vigorously with intravenous antibiotics. A combination of a second-generation cephalosporin, an aminoglycoside and metronidazole should be used. These together will have coverage for Gram-positive, Gram-negative (including pseudomonas) and anaerobes. CT scanning of the temporal bone should be performed to delineate the extent of the disease. In diabetic patients, the control of blood sugar level plays an important role. Hyperbaric oxygen therapy has been used in patients with severe disease with good result. Surgical treatment of this condition is purely secondary. The traditional mastoidectomy is rarely useful as the disease does not spread through the mastoid air cells. However, aggressive debridement of surrounding necrotic soft tissues and drainage of secondary local abscesses are important.

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