Atypical electroencephalographic pattern in a patient with subacute sclerosing panencephalitis.

Subacute sclerosing panencephalitis (SSPE) has become rare since the widespread use of the measles vaccine. In this patient with a 5 month history of seizures and progressive dementia due to SSPE, the atypical electroencephalographic pattern was characterized by generalized spike-and-wave discharges, maximal on the right, associated with clinical seizures. After diazepam (intravenously), more typical periodic complexes appeared.