AUDITORY BRAINSTEM RESPONSES IN JAUNDICED NEWBORNS

Abstract

This study was designed to determine whether Auditory Brainstem Responses (ABR) may reveal brainstem dysfunction caused by hyperbilirubinemia, whether exchange transfusion (ET) may have a beneficial effect on this dysfunction and if ABR is a rebiable test for assessingthe risk of bilirubin encephalopathy. In 18 full term jaundiced infants who needed an ET a total of 96 ABRs were evoked:33 before and 33 after the ET; 14 ABRs (9 neonates) one week after the ET and 16 ABRs (9 neonates) at a mean age of 6 months. The pre -ET bilirubin values were not very high(23.2±2.6mg/dl). From the 33 pre-ET ABRs 23 (16 newborns) were abnormal:only 2 out of the 18 newborns had normal pre-ET ABRs bilaterally. From the 23 abnormal pre-ET ABRs 19 (13 newborns) became normal immediately after the ET; 3 ABRs (2 newborns) were normal one week after the ET and the remaing ABR(1newborn) was still abnormal at the age of 6 months. At that age this baby was hypertonic.Abnormal ABR showed absence of waves V and I and an increased brainstem transmission time (5.10±0.33ms before vs 4.86±0.51ms after ET, p<0.005). Our data indicate thar a)hyperbilirubinemia even at levels not very high may cause brainstem dysfunction which in most cases is reversible with ET b)ABR may detect this dysfunction and c)babies with an abnormal post-ET ABR are at high risk for developing bilirubin encephalopathy.