Subacute sclerosing panencephalitis.

Introduction Subacute sclerosing panencephalitis (SSPE) is a rare disease which predominantly affects children of school age. The clinical features include an insidious afebrile onset with behavioural disturbance and progressive dementia sometimes associated with epilepsy. Later akinetic mutism and myoclonic jerks with pyramidal and extrapyramidal signs appear. Finally there is progressive decortication leading to death within months or at most 2 years. Spontaneous recovery though very rare has been reported (Pearce & Barwick, 1964; Cobb & Morgan-Hughes, 1968; Resnick, Engel & Sever, 1968). There is a paretic colloidal gold curve in the cerebrospinal fluid (CSF) but the cell count and protein are usually within normal limits. The electroencephalogram records taken early in the illness may not show periodic complexes but these typically occur later. The interval between the bilateral high amplitude slow wave complexes diminishes as the disease progresses. The record may be more abnormal on one side than the other with some clinical and radiological features suggesting a space-occupying lesion. Finally the clinical diagnosis may be confirmed by taking a brain biopsy during life. The aetiology of SSPE has remained obscure until recently and a conference was held in 1967 to review the evidence for a viral aetiology of the disease (Sever & Zeman, 1968). We may now consider the contributions of light and electron microscopy, virology and immunology towards the elucidation of of the aetiology of this disease.