Neurodevelopmental outcome of severe neonatal hemolytic hyperbilirubinemia

Abstract

We recruited 128 neonates with hyperbilirubinemia over a 5-year period (1995-2000) to study the short- and long-term effects of hemolytic hyperbilirubinemia on the auditory brainstem pathway and neurodevelopmental status. These children were divided into two groups: (1) a hemolytic group (n = 29; ABO incompatibility [n = 19], Rh incompatibility [n = 1], glucose-6-phosphate dehydrogenase deficiency [n = 8] and both ABO incompatibility and glucose-6-phosphate dehydrogenase deficiency [n = 1]) and (2) a nonhemolytic group (n = 99). All received phototherapy. Exchange transfusions were performed for four (13.8%) in the hemolytic group and three (3%) in the nonhemolytic group. The brainstem auditory evoked potential was recorded at a mean age of 3.2 months in the hemolytic group and 3.1 months in the nonhemolytic group. Serial brainstem auditory evoked potential assessments were performed until 2 years of age (3 in the hemolytic group and 18 in the nonhemolytic group). All had regular physical, neurologic, visual, and auditory evaluation until 3 years of age. The rate of exchange transfusion was significantly higher in the hemolytic group than in the nonhemolytic group (P < .05). Brainstem auditory evoked potential abnormalities at the initial assessment occurred in three (10.4%) in the hemolytic group (all related to ABO incompatibility) and nine (9.1%) in the nonhemolytic group. At 2 years, the brainstem auditory evoked potential returned to normal except in three cases with a slightly increased hearing threshold (one [3.5%] in the hemolytic group at 60 dB nHL and two [2%] in the nonhemolytic group at 50 dB nHL]). There were no significant differences in the rate of brainstem auditory evoked potential abnormalities at the initial or subsequent assessments between both groups. All except five cases had a normal neurodevelopmental outcome at 3 years (three [two with ABO incompatibility and one with glucose-6-phosphate dehydrogenase deficiency] in the hemolytic group [10.4%] and two [2%] in the nonhemolytic group). All had mild motor delay and hypotonia, which returned to normal at 3 years. The rate of abnormal neurodevelopmental outcome was higher in the hemolytic group than in the nonhemolytic group, although with no significant difference between both groups (P = .08). All five cases in both groups with abnormal neurodevelopment had a normal brainstem auditory evoked potential at the initial assessment. There was no relationship between the abnormal initial brainstem auditory evoked potential and the final neurodevelopmental outcome. The toxic effect of hyperbilirubinemia on the auditory brainstem pathway and neurodevelopmental status in our cohort was transient. The prognosis of neonatal hemolytic hyperbilirubinemia in our Chinese cohort is excellent, possibly owing to an aggressive early-intervention approach.