Event-related potentials (P300) and EEG activity in childhood partial epilepsy

To clarify the relationship between the cognitive function and EEG activity, auditory event-related potentials (P300) were examined in 72 patients with partial epilepsy. Twenty-six patients (67 trials) had idiopathic partial epilepsies (IPE), and 46 (118 trials) symptomatic or cryptogenic partial epilepsies (SPE). For this study, patients undergoing carbamazepine monotherapy with a dose of less than 16 mg/kg/day were selected to rule out the effects of anti-epileptic drugs. The results were as follows: (1) The P300 latency tended to be prolonged in association with the EEG slowing in both epileptic groups. (2) There was no clear relationship between the frequency of paroxysmal discharges and the P300 latency. (3) The P300 latency was slightly prolonged in the patients with temporal foci compared with that in ones with extra-temporal foci. (4) There was no significant relationship between the generalization of focal paroxysmal discharges and the P300 latency. These results suggested that the influence of EEG abnormalities (particularly paroxysmal discharges) on the P300 latency is relatively little, and the cognitive dysfunction in partial epilepsies mainly originates from other factors such as the epileptogenic lesion itself.