1H MR spectroscopic characteristics of kernicterus: a possible metabolic signature.

BACKGROUND AND PURPOSE MR examination of infants with kernicterus shows abnormal changes in signal intensity in various parts of the brain, including the globus pallidus and subthalamic regions. The purpose of this study was to retrospectively analyze proton ((1)H) MR spectroscopic data to see if the MR spectroscopic profiles of infants with hyperbilirubinemia and symptoms of kernicterus provide new insights into the pathophysiology of bilirubin neurotoxicity. METHODS Six patients aged 3 days to 3 weeks, with hyperbilirubinemia and symptoms of kernicterus underwent MR imaging and MR spectroscopy with a single-voxel point-resolved spectroscopic sequence. The voxel of interest was centered in the basal ganglia with CSF excluded. Quantitative analysis was done by using LCModel. Between-subject comparisons were based on metabolite ratios relative to creatine. RESULTS Ratios of taurine, glutamate and glutamine, and myoinositol relative to creatine were significantly elevated (P < .001), whereas the ratio of choline to creatine was significantly decreased (P < .001) compared with normal values published for this age group. Lactate levels were not significantly elevated. CONCLUSION Kernicterus has a characteristic signature that is detectable on (1)H-MR spectroscopy. Our results are generally in agreement with what is known about bilirubin pathology, and the finding of increased glutamate and glutamine and decreased choline ratios indicates a possible link between hepatic encephalopathy and kernicterus. This observation may help in elucidating the pathophysiology of bilirubin neurotoxicity.