Changes in auditory brainstem responses in hyperbilirubinemic infants before and after exchange transfusion.

Auditory brainstem responses (ABR) were evoked, before and after exchange transfusion, in an effort to determine whether hyperbilirubinemia is associated with acute effects on brainstem function of neonates. Nine full-term infants with hemolytic disease received exchange transfusion for conventional serum bilirubin concentration indications (mean 22.3 +/- 1.4 mg/dL). In three infants, wave-absence before exchange transfusion was followed by appearance of the waves after exchange transfusion. Other significant alterations observed in the group after exchange transfusion were increase of wave amplitudes and reduction of interpeak latencies (brainstem transmission time 5.80 +/- 0.36 ms after exchange transfusion compared with 6.25 +/- 0.30 ms before exchange transfusion, P less than 0.001). These improvements are considered to have been brought about by removal of bilirubin from the body and from the brainstem during exchange transfusion. Acute brainstem toxicity appears to occur in a percentage of infants with hyperbilirubinemia at serum levels commonly seen in clinical practice. These changes appear to be rapidly reversible with exchange transfusion.