Short- and Long-Term Outcome of Severe Neonatal Nonhemolytic Hyperbilirubinemia

Abstract

We studied the effects of hyperbilirubinemia on brainstem auditory pathways and neurodevelopmental status in 99 full-term neonates with severe nonhemolytic hyperbilirubinemia (total serum bilirubin level = 301 to 500 micromol/L) born between 1995 and 2000. These were divided into three groups: group 1, moderate hyperbilirubinemia (n = 30; mean maximum total serum bilirubin = 320.7 micromol/L or 18.9 mg%); group 2, severe hyperbilirubinemia (n = 63; mean maximum total serum bilirubin = 369.0 micromol/L or 21.7 mg%); and group 3, super hyperbilirubinemia (n = 6; mean maximum total serum bilirubin = 457.2 micromol/L or 26.9 mg%). All received phototherapy, and three neonates also had exchange transfusion. Initial brainstem auditory evoked potentials were recorded in all at the mean age of 3.1 months (range 1-9 months). At initial assessment, only nine neonates (9.1%) had abnormal brainstem auditory evoked potentials. All except two returned to normal at 2 years. These two children had a hearing threshold at 50 nHL. We then compared serial brainstem auditory evoked potentials until 2 years for these nine cases with initial abnormal brainstem auditory evoked potentials, and nine cases with initial normal brainstem auditory evoked potentials were recruited for comparison. All 99 children had regular physical, neurologic, visual, and auditory assessments every 3 to 6 months until the age of 3 years. There was no significant correlation between demographic factors (gender, gestational age, or birthweight), maximum total serum bilirubin, and total serum bilirubin at discharge with an abnormal brainstem auditory evoked potential. There was no significant difference in the rate of brainstem auditory evoked potential abnormalities between the three groups: moderate (10%), severe (7.9%), and super (16.7%). All had normal neurodevelopmental status at 3 years. Only two children had transient mild motor delay and hypotonia, and both had normal brainstem auditory evoked potentials. There was no relationship between the abnormalities of the brainstem auditory evoked potentials and neurodevelopmental status. None of the three children receiving exchange transfusion had abnormal brainstem auditory evoked potentials or neurodevelopmental outcome. With the neurophysiologic and clinical outcomes in our cohort with severe nonhemolytic hyperbilirubinemia, we propose that the toxic effect of hyperbilirubinemia on auditory brainstem pathways might be transient provided that prompt treatment is initiated.

Is very early hearing assessment always reliable in selecting patients for cochlear implants? A case series study

“…Similar cases had already been reported [18,19]. High levels of unconjugated bilirubin have been associated with neuron damage, and the auditory brainstem nuclei and inferior colliculi are often the first to be involved, with consequent hearing abnormalities [20].…”

Reversible auditory brainstem responses screening failures in high risk neonates

“…However, an unusually extended period of ABR recovery has been suggested by other researchers. Wong et al [8] found that most abnormal ABR returned to normal at 2 years in a group of term babies suVering from severe hyperbilirubinemia. Kitagawa et al [19] reported ABR and behavioral hearing tests recovery in children with congenital CNS anomalies, which in some cases took several years to occur.…”

“…Despite this widely accepted rule, transient ABR abnormalities and reversible sensorineural hearing losses have been sporadically reported. SigniWcant improvement or complete recovery of ABR thresholds in HR neonates treated for hyperbilirubinemia is probably the most characteristic example of ABR reversibility [7,8]. Complete or partial restoration of ABR has been infrequently reported in HR infants [9] and pediatric patients suVering from a variety of medical conditions, such as hypoxia/ischemia [10], metabolic [11] and neurologic diseases [12,13], sudden idiopathic hearing loss [14] and meningitis [15].…”

A study of predictors & prevalence of neurodevelopmental outcome in hyper-bilirubinemic neonates admitted in NICU

“…Similar decrease in prevalence has been reported by Chen et al (10.42% in hemolytic group and 2% in non-hemolytic group were neurodevelopmentaly abnormal at initial evaluation and returned to normal on follow up at 3 years). (4) Yilmaz et al in 2001 reported neurodevelopmental abnormalities in 11.5% cases in their study using DDST. (5) This prevalence is quite similar to the prevalence of neurodevelopmental abnormalities in our study (10.42%).…”