AUDITORY EVOKED BRAIN-STEM RESPONSES IN ICTERIC NEWBORN ALTERATIONS AFTER EXCHANGE TRANSFUSION

We report the changes in the auditory brain-stem responses (ABRs) in 5 term infants afterexchange transfusion (ET) for non conjugated hyperbilirubinemio, due to ABO incaipatibility. The intra erythrocyte bilirubin level remained within normal limits. All infants were free of other risk factors known to alter ABRs. ABRs were studied sequentially before ET, and 1,24,48 hours after ET. Controls were realized at 1 and 12 months. ABRs were obtained with a Medelec MC III signal averager. Filtered clicks (2500sec−1), at repetition rates of 10.sec−1, were presented for each ear at 80dbHL after estimating the click threshold. Before ET, we observed a R-L asymetry for interpeak interval I-V. In 3 patients, during the 48 hours following ET, we observed modifications of I-V intervals according to variations of bilirubin level (BL). In 2 patients, I-V decreased with a stability of BL after ET. The waves III and V were the most altered by BL changes. At 1 month, I-V intervals were higher than reference values for the some post-conceptional age, but were different for each ear. At 1 year, ABRs were normal. ABRs may provide a useful objective and non invasive method to evaluate the acute sensori-neural effects of acute hyperbilirubinemia. BL, even for acceptable increase, may hove a deleterious influence on ABRs. But since our results suggest a reversible neurotoxicity it seems important to hove later controls of ABRs.