Generalized sharp and slow wave and electrodecremental seizure pattern in subacute sclerosing panencephalitis.

Although subacute sclerosing panencephalitis (SSPE) often presents with a characteristic EEG pattern, a 13-year-old boy with a confirmed diagnosis of SSPE had several EEG features that are unusual for this condition, namely, generalized sharp and slow wave (slow spike and wave) discharges during the waking record, an electrodecremental pattern associated with clinical seizures, and activation of the typical periodic complexes of SSPE only during sleep.