Effects of prenatal exposure to carbamazepine on brainstem auditory evoked potentials in infants of epileptic mothers

The purpose of this study was to determine if there are any correlations between carbamazepine serum levels of epileptic mothers during pregnancy and the brainstem auditory evoked potentials in their infants as an index of drug neurotoxicity in newborns exposed prenatally. We included 20 epileptic mothers with carbamazepine medication and their 20 otherwise healthy infants. The study was conducted from September 1, 1993, to December 15, 1999. Serum carbamazepine determinations were performed monthly by enzymatic immunoanalysis in the mothers, and the averages for each trimester during pregnancy were calculated. Brainstem auditory evoked potentials were performed at 10.2 +/- 4.6 weeks of postnatal life. Pearson's correlations were calculated between carbamazepine serum levels during pregnancy and waves and interwave intervals of brainstem auditory evoked potentials. Both examinations were performed without knowledge of the results of the other investigations. No alterations in the infants' brainstem auditory evoked potentials were evident, and carbamazepine determinations were within therapeutic levels. Significant Pearson's correlations between latencies of waves III and V and third trimester of carbamazepine serum concentration levels and I-V interwave intervals to third-trimester minimum serum levels of carbamazepine were found. The findings suggest that the higher carbamazepine levels in mothers are related to increased latencies in waves III and V and I-V interwave intervals in infants subclinically, which could be an early index of fetal neurotoxicity.