Auditory event-related potentials in benign childhood epilepsy with centrotemporal spike: the effects of carbamazepine.

To clarify the relationship between cognitive function and CBZ therapy, auditory event-related potentials (P300) were examined in 23 patients with Benign Childhood Epilepsy with Centrotemporal Spike (BCECT) compared with 54 normal controls. The results were 1) the mean P300 latency in BCECT (368 +/- 29 msec) was significantly prolonged compared with that in normal controls (349 +/- 30 msec), but most individual patients showed normal values. 2) The prolongation of P300 latency was greatest during the course of therapy. 3) On repeated examination of P300, P300 latency was found to gradually become shorter with age in spite of continuous CBZ therapy. At initiation of CBZ therapy, the P300 latency became shorter; on the other hand, P300 latency became shorter with the discontinuation of CBZ. 4) The age-corrected P300 latency showed a significant positive correlation with the serum concentration of CBZ. Our results suggest that CBZ therapy has both an undesirable effect (chronic impairment) and a desirable effect (improvement of underlying dysfunction caused by epileptogenesis) on cognitive function.