Change of brainstem auditory evoked potential(BAEP)in newborns with different serum bilirubin level

Objective To explore the relationship between the changes of brainstem auditory evoked potential(BAEP)signal and hyperbilirubinemia in the neonates,and provide evidences for diagnoses of bilirubin encephalopathy and prediction of outcome.Methods Totally 100 hospitalized patients with hyperbilirubinemia were enrolled during January 2005 to January 2007 in the First Affiliated Hospital of Zunyi Medical College,and were divided into two groups:(1)Group A(40),serum bilirubin(TSB) 342 μmol/L(20 mg/dl);(2)Group B(60),TSB between 221～342 μmol/L(12.9～20 mg/dl);the two groups were included in study as cases.Group C,50 normal term neonate with a peak serum bilirubin 221 μmol/L(12.9 mg/dl)were included as controls.All cases received initial BAEP within 24 hours of hospitalization.Repeated BAEP was done in all abnormal cases when serum bilirubin levels fell below 85 umol/L.All abnormal cases were followed until BAEP came to normal or till the age of one year.Results(1)Compared to the control group,the incidence of abnormal BAEP was higher in group A and group B,the difference being very significant(P 0.05).The commonest abnormality seen is prolongation of latencies of various waves and prolongation of various intervals.Other abnormalities observed were absence of one or more wave forms at 85 dB.There was no difference between group A and group B(P 0.05),but the distribution of the abnormality was different between group A and group B(P 0.05).(2)When serum bilirubin levels fell below 85 μmol/L,the abnormalities on initial BAER reverted back to normal in most cases,The difference being very significant(P 0.05).The incidence of abnormal BAEP is significant difference between group A and group B when serum bilirubin levels come down(P 0.05).The follow-up revealed,among the 53 patients with abnormal BAEP,46 patients became normal and 7 patients with lasting abnormal BAEP had nervous system sequela.Conclusion(1)Abnormal BAEP is the important feature of neonatal hyperbilirubinemia.(2)When TSB 221 μmol/L,the BAEP change may happen,which reveals that the brain is damaged,and that is an important objective indicator in the early diagnosis of bilirubin encephalopathy.(3)Permanent abnormal BAEP indicates bad prognosis.