The Relationship between Severe Hyperbilirubinemia and Abnormal Auditory Brainstem Response in children

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). 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. 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). Our study showed a relevant association between bilirubin levels less than 20 mg/dl and abnormal ABR.