Impaired function of the auditory brainstem in term neonates with hyperbilirubinemia

Objective: We studied maximum length sequence brainstem auditory evoked response in term neonates with hyperbilirubinemia to further our understanding of hyperbilirubinemia on the neonatal auditory brainstem and to determine if maximum length sequence technique improves detection of brainstem auditory impairment due to bilirubin neurotoxicity. Methods: Maximum length sequence brainstem auditory evoked response was recorded and analysed shortly after confirming total serum bilirubin levels greater than 15 mg/dL in fifty-seven term neonates with hyperbilirubinemia. Results: Most wave latencies and interpeak intervals in maximum length sequence brainstem auditory evoked response in the neonates with hyperbilirubinemia were correlated with the level of total serum bilirubin at some or most click rates used. Compared with age-matched normal term controls, wave V latency in these neonates was increased significantly at all 91–910/s click rates (p < 0.05–0.001). The I–V and I–III interpeak intervals were also increased significantly at all these rates, and the III–V interval increased at 227–910/s clicks (p < 0.05–0.001). The differences between the neonates with hyperbilirubinemia and the controls were more significant at higher than at lower click rates. The slopes of wave V latency-rate function and I–V and III–V interval-rate functions were all significantly increased. By comparison, the abnormalities in conventional BAER were less significant, with only I–III and I–V intervals were increased (both p < 0.05). Conclusions: Functional status of the auditory brainstem is impaired in neonatal hyperbilirubinemia. Maximum length sequence technique at high click rates improves detection of bilirubin neurotoxicity to the neonatal auditory brainstem, particularly for the more rostral regions.