SPECIAL TYPES OF PERIODIC LATERALIZED EPILEPTIFORM DISCHARGES ASSOCIATED WITH CONFUSIONAL STATE IN CEREBRAL-CIRCULATION INSUFFICIENCY

A peculiar type of periodic lateralized epileptiform discharges (PLEDs ) was recorded on 22 EEGs performed in 11 patients. They were characte rized by bursts of sinusoid activity around 7-9 Hz, usually followed b y a slow wave, lasting less than 500 ms, with a period less than 2 s, and these sequences could be continuous over several days. We propose to name this pattern 'periodic sinusoid paroxysmal activity' (PSPA). P SPA was recorded mainly over both parieto-temporo-occipital regions, a lthough asymetrically. Sensory stimulations and anticonvulsants had no effect on PSPA. In three cases, mobilization of the head blocked PSPA . The spontaneous disappearance of PSPA was sometimes followed by clas sical PLEDs. PSPA was always associated with a confusional state and b ehavioural disturbances, and erratic distal clonic movements were seen in 6 cases. These symptoms disappeared as soon as PSPA ceased. Patien ts had either vascular risk factors or a previous cerebrovasculuar ins ult. The confusional state was associated with either lowered carotidi an bloodflow or probable global cerebral hypoperfusion due to a system ic pathology. A vascular origin of PSPA is likely, due to the presence of vascular risk factors, to the morphology of PSPA and to the provok ing and inhibiting factors.