Evaluation of neurological effects of indirect hyperbilirubinemia in late preterm infants with aEEG, NIRS and ABR

Indirect hyperbilirubinemia is a common clinical condition in newborns. However, when hyperbilirubinemia exceeds certain levels, if it is not treated appropriately and in a timely manner, it can cause serious adverse effects, especially in the neurological system, and even result in mortality. Therefore, clinical follow-up and timely and appropriate treatment of infants with hyperbilirubinemia is very important. In this study, cerebral cortical effects of indirect hyperbilirubinemia in late preterm infants were evaluated by amplitude electroencephalography (aEEG), cerebral blood flow monitoring by near infrared spectroscopy (NIRS), and brainstem effects by automatic auditory brainstem response (ABR) tests and the effects of indirect bilirubin on neurotoxicity were investigated. Patients born late preterm (350/7-366/7 gestational weeks) with indirect hyperbilirubinemia and receiving phototherapy (patient group) and newborns born at the same gestational weeks but whose indirect hyperbilirubinemia did not require treatment (control group) were included in the study. In the patient group, aEEG, NIRS and automatic ABR were performed at the beginning of phototherapy when the total serum bilirubin level was 2-3 mg/dl below the phototherapy limit. aEEG and NIRS were repeated on the 8th day after phototherapy and Denver II Developmental Screening Test (DGTT II) was performed at the 6th month. In the control group, aEEG, NIRS and automatic ABR tests were performed once. There were not statistically significant differences between the patient and control groups in terms of gender, maternal age, conceptual age, birth weight, height and head circumference. Hyperbilirubinemia was diagnosed at postnatal day 4.8±2.2. In the first aEEG recordings of the patient group; it was detected that 3.8% of the patients had normal, 69.2% had moderate, and 27% had severe influenced. In the first NIRS recordings; tissue oxygenation index (DOI) values were found to be outside normal values in 38.4% of the patients and fractionated oxygen extraction (FOE) values were found to be outside normal values in 73% of the patients. In automatic ABR tests performed before phototherapy; it was observed that 77% of the patients failed. All tests performed on the 8th day after phototherapy were completely normalized and DGTT II performed at the 6th month was found to be normal in all patients. In conclusion, indirect hyperbilirubinemia affects brain function in late preterm infants in the acute phase, but the effect is transient and completely reversible with the timely and appropriatly therapy. Keywords: Indirect Hyperbilirubinemia, aEEG, NIRS