A disorder involving inflammation and damage of the bones and cartilage of the base of the skull, caused by spread of infection from external ear infection .
Alternative Names
Osteomyelitis of the skull; Malignant otitis externa
Causes, incidence, and risk factors
Malignant otitis externa is a relatively uncommon complication of both acute otitis externa and chronic otitis externa (swimmer's ear, external ear infection ). It occurs in approximately 5 out of 10,000 people. Diabetics and persons whose immune system are compromised from diseases or medications are particularly susceptible to malignant otitis externa. The infection of external otitis, often caused by difficult-to-treat bacteria such as Pseudomonas , spreads from the floor of the ear canal to the adjacent tissues and into the bones of the base of the skull. The bones may be damaged or destroyed from the resulting infection and inflammation. The infection may further spread and affect the cranial nerves, the brain, or other parts of the body.
Signs and tests
Inspection of the ear may show otitis externa . The head around and behind the ear may be tender to touch. Neurological examination may show involvement of cranial nerves. A culture of drainage may show bacteria or fungus, usually the bacteria Pseudomonas . A head CT scan , skull X-rays , MRI scan of the head, or radionuclide scan may show osteomyelitis (bone infection) adjacent to the ear canal.
Treatment
The goal of treatment is cure of the infection. Treatment is often prolonged, lasting several months, because of the difficulty of treating the involved bacteria and the difficulties reaching an infection that is within bone tissue. Antibiotics that are effective against the involved microorganism are given for prolonged periods. They may be given intravenously or, occasionally, orally. Antibiotic therapy should be continued until scan or other tests show a marked reduction in the associated inflammation. Occasionally, surgical debridement of the skull is needed to allow drainage and to reduce deterioration of the bone.
Expectations (prognosis)
Malignant otitis externa usually responds to prolonged treatment but may recur.
Calling your health care provider
Call for an appointment with your health care provider if symptoms of malignant otitis externa develop. Call your health care provider if symptoms persist despite treatment, or if new symptoms develop. Go to the emergency room or call the local emergency number (such as 911) if convulsions , decreased consciousness , severe confusion , or similar symptoms develop.
Prevention
To prevent external ear infection , dry the ear thoroughly after exposure to moisture. Avoid swimming in polluted water and protect the ear canal with cotton or lamb's wool while applying hair spray or hair dye (if susceptible to otitis externa ). Treat acute otitis externa completely and do not stop treatment sooner than recommended by your health care provider to reduce the risk of it becoming malignant otitis externa. After swimming, 1 or 2 drops of a mixture of 50% alcohol and 50% vinegar in each ear will help to dry the ear and prevent infection.