EVENT-RELATED POTENTIALS SUGGEST SLOWING OF BRAIN PROCESSES IN GENERALIZED EPILEPSY AND ALTERATIONS OF VISUAL PROCESSING IN PATIENTS WITH PARTIAL SEIZURES

Event-related potentials were recorded in two auditory tasks and in on e visual task from 13 patients with partial seizures (PS), 12 patients with idiopathic generalized epilepsy (IGE), and healthy age-matched p articipants. IGE patients had delayed latencies in the auditory tasks, with the delay being reliable already at N1, and continuously increas ing at N2b and at P3. The P3 delay correlated with duration of epileps y both in IGE and in PS patients. In the visual task, the posterior N2 was delayed in PS patients, in particular in PS patients with tempora l focus. Resembling the delays as found in healthy elderly adults, the delays with auditory stimuli might reflect a slowing of brain process es as it occurs in healthy aging. The isolated delay of posterior N2 i n temporal PS patients might indicate a specific impairment of the occ ipito-temporal visual pathway. Taken together, event-related potential s prove to be a very sensitive instrument for measuring altered brain functioning in epileptic patients, when compared to measurement of ove rtly visible responses.