SSPE manifests, on an average, 7 years after the primary infection with measles. The peak incidence occurs at 7 to 15 years though it has been reported in the subjects aged 6 months to 30 years.
Manifestations include personality changes followed by generalized myoclonic jerks and, at times, grandmal seizures. With progression of the disease, the patient becomes demented, rigid and bedridden.
The disease invariably proves fatal within 2 years. CSF is normal except for high gamma globulin levels and measles antibody titer of more than 1 in 128 by complement fixation method.
EEG shows regularly repeated bursts of generalized high voltage slow wave complexes.
CT scan or MRI reveals variable cortical atrophy, ventricular enlargement and focal or multifocal low density lesions in white matter in established disease. Brain biopsy shows perivascular lymphocytic infiltration, inclusion bodies in neurons and glial cells, loss of neuronal cells, gliosis and, at times, growth of measles virus from cerebral tissue.
Management is by and large symptomatic and supportive. Inosiplex, 100 mg/kg/day in divided doses, causes some clinical improvement and prolonged survival. The disease is also termed DAWSON ENCEPHALITIS after the name of Dawson who first described it.