The Relationship between Severe Hyperbilirubinemia and Abnormal Auditory Brainstem Response (ABR) in Children

Introduction: Hyperbilirubinemia is one of the most common cause of congenital sensory neuronal hearing loss. These patients are screened by auditory brainstem response (ABR) test at bilirubin levels higher than 1% of gestational weight. Aim of this study is to determine whether hyperbilirubinemia less than 1% of gestational weight could induce hearing loss and abnormal auditory brainstem response (ABR). Materials and Methods: In this case control study the outcome of ABR test in children younger than 3 years old with a history of term delivery and hyperbilirubinemia (bilirubin level less than 1% of gestational weight) were compared with the control group without hyperbilirubinemia matched for age and gender. Results: Mean ABR amplitude (wave I, V) were significantly prolonged in neonates with jaundice compared with controls (P < 0.01). Based on receiver-operating characteristic curves, a bilirubin level of 0.6% of gestational weight was the best discriminator with a sensitivity and specificity of 100%. In logistic regression analysis the relative risk of having an abnormal ABR in bilirubin level > 0.6% gestational weight was 2.25 with 95% confidence intervals (CI) (1.44-3.89 and p=0.02). Conclusion: Our study showed a relevant association between bilirubin levels less than 20 mg/dl and abnormal ABR.