Stimulus-induced EEG complexes and motor spasms in subacute sclerosing panencephalitis.

Patients with subacute sclerosing panencephalitis (SSPE) typically present with spontaneous periodic, stereotyped electroencephalographic (EEG) complexes and motor spasms, which are not usually affected by sensory stimuli. This report describes two patients with SSPE in whom the EEG complexes and the motor movements occurred mainly in response to afferent stimuli. Various forms of stimuli were effective in precipitating the movements and EEG complexes, particularly when the stimulus was unexpected or startled the patient. During sleep, the EEG complexes spontaneously occurred in a more periodic fashion, typical of SSPE, but afferent stimuli were still effective in evoking the EEG complexes and associated motor spasms.