Auditory brainstem responses in neonatal hyperbilirubinemia and effect of therapy

Abstract

Objectives; To determine the effect of neonatal hyperbilirubinemia on auditory brainstem responses (ABRs) and evaluate ABR responses to lowering of bilirubin levels.Study Design: prospective case control trialSetting: tertiary referral center.Patients: 60 neonates (40 cases & 20 controls). Term appropriate for date(AFD) neonates with uncomplicated birth history and bilirubin level of ≥ 13 mg/dL were included as cases, those with bilirubin value of < 13 mg/dL were taken as controls.Interventions; First BERA examination was carried out within 24 hrs of the diagnosis of hyperbilirubinemia and repeat examination was done when total serum bilirubin came down to < 13 mg/dL with treatment. Comparisons were made between cases (before & after therapy) and controlResults; No abnormality in neonates with bilirubin < 18 mg/dL. Abnormal ABRs were observed in 24(60%) of the 40 cases studied, with therapy it reverted back to normal in 15(62%). The commonest abnormality noted was prolonged latency of wave V(42.5%), followed by prolonged latency of wave III(35%) and wave I(22.5%). Prolonged latency of wave I was found in only those with bilirubin > 20mg/dL. Inter peak latency of wave IV (Brain stem conduction time) was prolonged in 8 cases; it reverted to normal in all cases. Prolonged inter peak latency of wave I–III was observed in 7 cases, of which it reverted to normal in 6. Absent waves reappeared in 4 out of 5 cases, but abnormal amplitude ratios reverted to normal in only one of the 7 cases in which it was abnormal.Conclusions; about 60% of term A FD neonates with serum bilirubin of > 18mg/dL will demonstrate ABR changes. Most of these changes revert to normal early after therapy, indicating need for aggressive therapy in this subgroup of neonates.