Subacute Sclerosing Panencephalitis (SSPE)
Subacute sclerosing panencephalitis is a progressive, usually fatal brain disorder occurring months to usually years after an attack of measles. It causes mental deterioration, myoclonic jerks, and seizures. Diagnosis involves EEG, CT or MRI, CSF examination, and measles serologic testing. Treatment is supportive.
Subacute sclerosing panencephalitis (SSPE) is probably a persistent measles virus infection (see Measles). The measles virus is present in brain tissue.
SSPE occurs in about 7 to 300 cases per million people who had wild measles and in about 1 case per million people who received measles vaccine; all cases are probably due to unrecognized measles before vaccination. Males are more often affected. Onset is usually before age 20. SSPE is exceedingly rare in the US and Western Europe.
Often, the first signs are subtle—diminished performance in schoolwork, forgetfulness, temper tantrums, distractibility, and sleeplessness. However, hallucinations and myoclonic jerks may then occur, followed by generalized seizures. There is further intellectual decline and speech deterioration. Dystonic movements and transient opisthotonos occur. Later, muscular rigidity, dysphagia, cortical blindness, and optic atrophy may occur. Focal chorioretinitis and other funduscopic abnormalities are common. In the final phases, hypothalamic involvement may cause intermittent hyperthermia, diaphoresis, and pulse and BP disturbances.
SSPE is suspected in young patients with dementia and neuromuscular irritability. EEG, CT or MRI, CSF examination, and measles serologic testing are done. EEG shows periodic complexes with high-voltage diphasic waves occurring synchronously throughout the recording. CT or MRI may show cortical atrophy or white matter lesions. CSF examination usually reveals normal pressure, cell count, and total protein content; however, CSF globulin is almost always elevated, constituting up to 20 to 60% of CSF protein. Serum and CSF contain elevated levels of measles virus antibodies. Anti-measles IgG appears to increase as the disease progresses.
If test results are inconclusive, brain biopsy may be needed.