Subacute Sclerosing Panencephalitis
Subacute sclerosing panencephalitis, a progressive and usually fatal disorder, is a rare complication of measles that appears months or years later and produces mental deterioration, muscle jerks, and seizures.
Subacute sclerosing panencephalitis results from a long-term brain infection with the measles virus. The virus sometimes enters the brain during a measles infection. It may cause immediate symptoms of brain infection (encephalitis), or it may remain in the brain for a long time without causing problems.
Subacute sclerosing panencephalitis occurs because the measles virus reactivates; in the United States for reasons that are not known, the disorder occurs in about 1 or 2 people per 1 million who previously had measles. In very rare cases, a person who never had measles but received live measles vaccine may develop subacute sclerosing panencephalitis.
The number of people with subacute sclerosing panencephalitis is declining in the United States and Western Europe. Males are affected more often than females.
Symptoms and Diagnosis
The disorder usually begins in children or young adults, generally before age 20. The first symptoms may be poor performance in schoolwork, forgetfulness, temper outbursts, distractibility, sleeplessness, and hallucinations. Sudden muscular jerks of the arms, head, or body may occur. Eventually, seizures may occur, together with abnormal uncontrollable muscle movements. Intellect and speech continue to deteriorate. Later, the muscles become increasingly rigid, and swallowing may become difficult. The swallowing difficulty sometimes causes the person to choke on his saliva, resulting in pneumonia. The person may become blind. In the final phases, the body temperature may rise, and the blood pressure and pulse become abnormal.
A doctor makes the diagnosis based on the symptoms. The diagnosis may be confirmed by a blood test that reveals high levels of antibody to the measles virus, by an abnormal electroencephalogram (EEG), or by magnetic resonance imaging (MRI) or computed tomography (CT) scans that show brain abnormalities.
Prognosis and Treatment
The disease is nearly always fatal within 1 to 3 years. Although the cause of death is usually pneumonia, the pneumonia results from the extreme weakness and abnormal muscle control caused by this disease.
Nothing can be done to halt progression of the disease. Anticonvulsant drugs may be taken to control or reduce seizures.
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