MRA and ABR as Early Predictors of Bilirubin-Induced Neurologic Dysfunction in Full-term Jaundiced Neonates

Neonatal jaundice is a prevalent condition. It's typically a harmless phase that occurs as the body adjusts to bilirubin levels after birth, representing a balance between its production and elimination. When there's an increase in bilirubin production and a decrease in elimination, infants become at risk for dangerous hyperbilirubinemia, potentially leading to bilirubin encephalopathy. The range of neurological issues caused by excessive bilirubin is referred to as bilirubin-induced neurologic dysfunction. Detecting this condition early is crucial to prevent irreversible brain damage. Some of the neurological effects include gliosis, demyelination, and interference with glutamate uptake by astrocytes in the basal ganglia. Magnetic resonance spectroscopy (MRS) is an advanced imaging technique that holds promise for identifying these metabolic changes and aiding in the diagnosis and evaluation of neonates with hyperbilirubinemia. Bilirubin neurotoxicity particularly affects the auditory system, starting with the brainstem cochlear nuclei, followed by the auditory nerve. This damage can occur even without the classic signs of bilirubin encephalopathy and is known as auditory neuropathy spectrum disorder (ANSD). ANSD is characterized by abnormal auditory neural function, while cochlear microphonics and otoacoustic emissions remain normal. The impact on hearing can vary from subtle issues in sound processing to complete deafness. Abnormal results in auditory brainstem response (ABR) tests can indicate the presence of acute bilirubin encephalopathy (ABE), serving as the most common and earliest sign of ABE.