The Importance of Neuroimaging Follow-Up in Bilirubin-Induced Encephalopathy: A Clinical Case Review

Abstract

Introduction: Hyperbilirubinemia in newborns can lead to kernicterus, a severe form of neonatal encephalopathy caused by bilirubin toxicity. Despite timely interventions such as exchange transfusion, kernicterus can still develop, especially in high-risk infants. MRI is crucial for detecting early and evolving signs of bilirubin-induced brain damage. Case Report: We report a term newborn who developed severe hyperbilirubinemia and kernicterus despite receiving exchange transfusion. The infant presented on day 3 of life with jaundice, hypotonia, and feeding difficulties and had a bilirubin level of 51 mg/dL. After exchange transfusion, bilirubin levels normalized, but neurotoxicity persisted. Initial MRI at one month showed mild T1 hyperintensity in the hippocampi with no changes in the basal ganglia. At two months, T1 hyperintensities in the hippocampi partially resolved. By six months, MRI revealed T2 hyperintensities in the globus pallidus and hippocampal atrophy, consistent with kernicterus. Magnetic resonance spectroscopy (MRS) showed reduced N-acetylaspartate (NAA) levels, indicating neuronal loss. Discussion: MRI is essential in monitoring bilirubin-induced brain injury. In this case, early MRI findings showed mild hippocampal T1 hyperintensity, which resolved partially. At six months, T2 hyperintensities in the globus pallidus confirmed chronic bilirubin encephalopathy. MRS demonstrated a reduction in N-acetylaspartate, indicative of neuronal loss. Susceptibility-Weighted Imaging (SWI) showed no abnormalities, likely due to the myelination process in neonates. Conclusions: This case highlights the importance of repeated MRI in detecting bilirubin-induced brain damage. Early neuroimaging enables timely interventions and improves long-term neurodevelopmental outcomes in infants with severe hyperbilirubinemia.

Keywords: MRI; hyperbilirubinemia; kernicterus; neuroimaging; newborn.

Figure 1

Brain MRI performed during the subacute phase. Hyperintensity in the hippocampi on coronal (A) and axial (B) T1-weighted images (arrows, A,B). No evident changes were observed in the nucleo-capsular region, either in axial T1-weighted images (C) or in susceptibility-weighted images (D).

Figure 2

Brain MRI obtained at 6 months. (A) An axial T2-weighted image showing hyperintensity in globus pallidus bilaterally (arrows), a typical finding in chronic bilirubin encephalopathy; (B) an axial T2 DRIVE image showing tissue loss in both hippocampi (arrowheads), corresponding to the areas that previously showed T1 hyperintensity (see Figure 1) which are no longer detectable on a T1-weighted image (C).