Brain stem auditory evoked potential response in neonates after recovery from hyperbilirubinemia: A neurophysiological approach to screening neuronal hearing loss

Abstract

Objectives: Neonatal hyperbilirubinemia leads to neurological damages including encephalopathy and hearing loss. This study aimed to screen and evaluate the hearing loss in neonates after recovery from hyperbilirubinemia using the Brainstem evoked response audiometry (BERA) test. Materials and Methods: This cross-sectional comparative study was conducted in Physiology Department at Chitwan Medical College, Nepal. It included 20 age and sex-matched neonates recently recovered from hyperbilirubinemia and 20 normal healthy controls. The external acoustic canals of subjects were checked for any blockage or collapse before BERA testing. The BERA recordings were performed after the neonate’s natural sleep following a standard lab protocol explained by Taylor’s Evoked Potential in Clinical Testing. Results: The BERA wave latencies were delayed with a higher number of case group neonates I (IL-75%, IR-80%), III (IIIL-70%, III R-80%), and V (VL-80%, VR-85%) than those of controls. The percentage of neonates with delayed interwave latencies was comparable between groups. The neonate’s hearing sensitivity assessed using the grades of hearing impairment by WHO revealed slight (threshold of hearing left ear [THL]-25% and threshold of hearing right ear [THR]-30%) and moderate (THL-40% and THR-35%) grades among cases whereas no impairment (THL-60% and THR-55%) in controls. The hearing thresholds were more in cases. Conclusion: The auditory pathway is highly sensitive to elevated serum bilirubin. BERA detects even a minute degree of hearing damage seen after complete treatment of hyperbilirubinemia. Therefore, BERA is a helpful tool in the early screening of hearing impairment in neonates. This improves prognosis by early management so that the neurosensory systems develop to their full extent and one can enjoy a normal social life.