Abstracts

Rationale: P300 could detect subtle functional changes in central nervous system induced by antiepileptic drug. The latency of P300 reflects the speed of cognitive decision processes, and the amplitude of P300 is related to attention and motivation. To evaluate the changes of event-related potential after zonisamide (ZNS) administration, we measured the P300 in drug naïve epilepsy patients before and after ZNS administration. Methods: Twenty-six patients (M:F=13:13, mean age 29.3 ± 8.6 years) underwent auditory and visual P300 studies before and 1 - 4 months after ZNS medication. EEG recordings were done using an electrode cap with built-in 32 scalp electrodes based on the international 10-20 systems. For auditory P300 recordings, patients were presented with tones at two different frequencies (1 and 2kHz) using earphones. The non-target stimulus (1kHz) occurred 80%, and the target stimuli (2kHz) were randomly interspersed with the non-target stimuli at a probability of 20%. For visual P300 recordings, a small circle was a frequent stimulus and a large circle a rare stimulus. Patients were instructed to respond to the target stimulus by pressing a button. These patients received ZNS 100mg per day for the first 2 weeks and then 200mg per day for the second 2 weeks.Results: After ZNS treatment, auditory P300 latency was significantly prolonged at bilateral frontoparietal regions (at electrode F3, Fz, F4, FC3, FCz, FC4, CP3, CPz, P3, Pz, P4) (paired t-test, p=0.01~0.035). The visual P300 showed non-significantly prolonged latency after ZNS administration. Mean amplitudes of auditory and visual P300 were not changed significantly by ZNS (p >0.05). Conclusions: This result suggests that administration of ZNS in drug naive epilepsy patients induce the prolongation of auditory P300 latency.