Special types of periodic lateralized epileptiform discharges associated with confusional state in cerebral...

A peculiar type of periodic lateralized epileptiform discharges (PLEDs) was recorded on 22 EEGs performed in 11 patients. They were characterized by bursts of sinusoid activity around 7-9 Hz, usually followed by 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). PSPA was recorded mainly over both parieto-temporo-occipital regions, although 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 classical PLEDs. PSPA was always associated with a confusional state and behavioural disturbances, and erratic distal clonic movements were seen in 6 cases. These symptoms disappeared as soon as PSPA ceased. Patients had either vascular risk factors or a previous cerebrovascular insult. The confusional state was associated with either lowered carotidian bloodflow or probable global cerebral hypoperfusion due to a systemic pathology. A vascular origin of PSPA is likely, due to the presence of vascular risk factors, to the morphology of PSPA and to the provoking and inhibiting factors.