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 electroencephalography, CT or MRI, cerebrospinal fluid examination, and measles serologic testing. Treatment is supportive.
Subacute sclerosing panencephalitis (SSPE) is thought to be a persistent measles virus infection. The measles virus is present in brain tissue in patients with this disease.
Historically, SSPE occurred in approximately 7 to 300 cases per million people who had wild measles and in approximately 1 case per million people who received measles vaccine; post-vaccination cases are thought to be due to unrecognized measles before vaccination. Males are more often affected.
The risk of developing SSPE is highest in people who contract measles at < 2 years of age. Onset is usually before age 20.
SSPE is exceedingly rare in the United States and Western Europe because of widespread measles vaccination. However, analyses of more recent measles outbreaks suggest that the incidence of SSPE may be higher than previously thought, perhaps as high as 40 to 1700 cases per million measles cases (1). This incidence is of particular concern given the increasing outbreaks of measles among unvaccinated populations.
General reference
1. Wendorf KA, Winter K, Zipprich J, et al: Subacute sclerosing panencephalitis: The devastating measles complication that might be more common than previously estimated. Clin Infect Dis 65(2):226–232, 2017. doi: 10.1093/cid/cix302
Symptoms and Signs of SSPE
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 blood pressure disturbances.
Diagnosis of SSPE
Serologic testing
Electroencephalography (EEG)
Neuroimaging
SSPE is suspected in young patients with dementia and neuromuscular irritability.
EEG, CT or MRI, cerebrospinal fluid (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.
Treatment of SSPE
Supportive care
Anticonvulsants and other supportive measures are the only accepted treatments.
Prognosis for SSPE
The disease is almost invariably fatal within 1 to 3 years (often pneumonia is the terminal event), although some patients have a more protracted course.
A few patients have remissions and exacerbations.
