A Study of Auditory Brainstem Responses in Neonates with Hyperbilirubinemia and Their Neurodevelopmental Outcome

ABSTRACT

Neonatal hyperbilirubinemia is a significant risk factor for the developemtn of otoneurologic disorder. Hyperbilirubinemia resulting in kernicterus produces widespread neuronal damage with the most common sites of staining and destruction involving the hippocampus, basal ganglia and the brainstem nuclei in the floor of the fourth ventricle, including the dorsal cochlear nucleus. ABR may be a useful tool for the monitoring early bilirubin toxicity and postcteric sequelae in infants. This study attempts to evaluate the clinical neurodevelopmental outcome in hyperbilirubnemic infants requiring exchange transfusion through the assessment of ABR. Eight hyperbilirubinemic neonates with severely abnormal ABR findings and twelve hyperbilirubinemic neonates with normal ABR findings were studied to assess their neurodevelopemental outcome. The results were as follows; 1) There were 8 severely abnormal ABR cases, including 5 cases of bilateral flat wave and 3 cases of unilateraly elevated hearing throeshold. 2) The major cause of hyperbilirubinemia was ABO incompatibility(65%) 3) Significant clinical finding associated with severely abnormal ABR was kernicterus(p<0.05) 4) Significant laboratory findings associated with severely abnormal ABR were lower levels of hemoglobin and hematocrit(p<0.05) 5) 2 cases of bilateraly flat ABR and 3 cases of unilaterally elevated hearing threshold could be classified into sensorineural type hearing defect by latency-intensity function curve. 6) At the follow up tests of 3 cases of bilaterally flat ABR, 2 cases showed no change and 1 case showed mild improvement. 7) Among 5 follow up cases of severely abnormal BR, only 1 case showed normal neurodevelopmental outcome, 3 cases showed major neurodevelopmental defect and 1 case showed minor neurodeveoplemental defect. Among them, 1 case has had definite hearing disability.