Complications
Early bilirubin-induced neurologic toxicity can be detected by measuring brain stem auditory evoked responses. It is presumably a result of entry of bilirubin specifically into the neural cells of the auditory pathway. A peak total serum bilirubin level of >23 mg/dL has been suggested to be predictive of later hearing impairment.[90]
In jaundiced neonates, there is absence or prolonged wave peak latencies and inter peak latencies. Treated babies showed a tendency toward recovery in their auditory evoked responses.[91][92][93]
Treatment consists of phototherapy and/or exchange transfusion to decrease serum unconjugated bilirubin levels, which in turn would presumably decrease brain bilirubin levels and normalize the auditory evoked responses.
Bilirubin is a cellular poison in the brain and is preferentially taken up by the basal ganglia, globus pallidus, putamen, and caudate nuclei. It is said to disrupt the energy metabolism of the cells by affecting mitochondrial function.
The initial phase is characterized by lethargy, hypotonia, and poor sucking with a high-pitched cry.
In the intermediate phase, the neonate is irritable, with variable tone, and a high-pitched cry.
In the advanced phase, the neonate goes into deep stupor or coma, with hypertonia (retrocollis and/or opisthotonus).
Treatment consists of phototherapy and/or exchange transfusion to decrease serum unconjugated bilirubin levels, which in turn would presumably decrease brain bilirubin levels and normalize neurologic function.
These include electrolyte disturbances, bleeding, infection, cardiac arrhythmias, thrombosis with embolization, necrotizing enterocolitis, and graft-versus-host disease. Irradiation of blood is recommended prior to using it for exchange transfusion to decrease the risk of graft-versus-host disease.
Proper monitoring is essential during exchange transfusions. Treatment is given if the infant is symptomatic and/or has abnormal laboratory results for specific complications: for example, calcium infusion for hypocalcemia, platelet transfusions for thrombocytopenia.[7][44][48]
Kernicterus is diagnosed pathologically by gross yellow staining and necroses of neurons in the basal ganglia, hippocampal area, and cerebellum. It occurs secondary to the entry of bilirubin into the brain, which causes a disruption of cellular energy metabolism in the basal ganglia, hippocampal area, and cerebellum.
The condition is rare: the pilot kernicterus registry in the US reported 125 babies affected from 1984 to 2002.
Cerebral cortex is usually spared. If the neonate survives, the clinical features include chorio-athetoid cerebral palsy, paralysis of upward gaze, sensorineural hearing loss, dental dysplasia, and intellectual deficits (less often in the intellectual disability range).[94]
Kernicterus can be prevented by early and aggressive phototherapy and/or exchange transfusion.
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