Effects of phototherapy on outer hair cell function in infants with hyperbilirubinemia

Abstract

Introduction: Hyperbilirubinemia in newborns has been hypothesized to cause damage to inner ear, thus leading to sensorineural hearing loss. Phototherapy is treatment protocol in most of the hospitals for newborns with high bilirubin levels. The present study aimed to determine the effects of phototherapy on outer hair cell (OHC) function of cochlea. Methods: Twenty-two neonates with hyperbilirubinemia undergoing phototherapy and 22 neonates without any high-risk registers were included in the study. Distortion product otoacoustic emission (DPOAE) was administered before and after phototherapy. Auditory brainstem response (ABR) evaluation was done during the postphototherapy recording. Results: Results showed that DP amplitude and signal-to-noise ratio improved significantly after phototherapy. ABR evaluation revealed; 19 neonates had significantly prolonged wave V latency compared to normal, whereas no peaks were identified among three neonates. Most of the infantile hyperbilirubinemia are found to be harmless until and unless treatment is not initiated at the earliest, but still it is found that short-term increase in bilirubin level can induce temporary changes in OAEs and ABR measures. ABR needs to be repeated over a period of time for these three neonates to rule out auditory dyssynchrony (AD). Conclusion: The results indicate that phototherapy has temporary effects on OHC function and can improve as the bilirubin levels reduce. Follow-up testing over a period of time helps in discriminating the sensory pathology and AD.