Objective and background: Prevention of bilirubin encephalopathy relies on the detection of newborns who are at risk of developing serious hyperbilirubinemia. The objective of this study was to reassess the clinical syndrome of kernicterus as neurodiagnostic studies have become more readily available and can be used to evaluate these infants.
Methods: The study population was neonates born at term or near term admitted to The Hospital for Sick Children in Toronto, Ontario, Canada, between January 1990 and May 2000. During the study period, there were 9776 admissions (average number of admissions per year--888 infants). The inclusion criteria were that patients had total serum bilirubin levels of >400 micromol/L at the time of diagnosis and no evidence of hypoxic ischemic encephalopathy. Records were reviewed to establish neurodevelopment outcomes.
Results: Twelve neonates (nine males) were identified. Bilirubin levels at the time of diagnosis ranged from 405 to 825 micromol/L. Causes of these elevated levels included glucose-6-phosphate dehydrogenase deficiency (seven patients), dehydration (three patients), sepsis (one patient), and was undetermined in one patient. Abnormal visual evoked potentials were found in three of nine patients and abnormal brainstem auditory evoked potentials in seven of ten patients. Abnormal electroencephalograms were documented in five patients studied. Brain magnetic resonance imaging results were abnormal in three of four patients.
Conclusions: Magnetic resonance imaging typically showed an increased signal in the posteromedial aspect of the globus pallidus and was, therefore, useful in the assessment of the structural changes of chronic bilirubin encephalopathy after kernicterus.