Kernicterus - Clinical
Kernicterus
Clinical
The term "kernicterus" has many meanings which differ according to the context. Coined in 1904, it originally referred to the yellow staining of the basal ganglia seen at autopsy in babies dying with severe hyperbilirubinemia. Since the 1950s, it has traditionally been used to describe the pathologic findings of bilirubin toxicity in the brain. However, it has also been used in reference to the clinical symptomatology of both acute and chronic bilirubin encephalopathy. Recently, the term "bilirubin-induced neurologic dysfunction" (BIND), along with a descriptive scoring system has been introduced. Finally, the AAP has recommended that the term "acute bilirubin encephalopathy" be used to describe the acute manifestations of bilirubin toxicity seen in the first weeks after birth and that the term "kernicterus" be reserved for the chronic and permanent neurologic sequelae of bilirubin toxicity.The majority of full-term infants with marked hyperbilirubinemia who have either died with pathologically proven kernicterus or survived and developed chronic clinical kernicterus exhibited a definite neurologic syndrome as neonates. The major features of this acute bilirubin encephalopathy involve abnormalities of level of consciousness, tone and movement and brainstem function, especially as related to feeding and cry. There are 3 major phases of worsening severity which usually evolve over several days. It should be kept in mind, though, that even the historical literature from the era when kernicterus was much more common showed that up to 15% of babies with subsequent kernicterus failed to demonstrate any definite neonatal neurologic symptoms.In the first year of life, babies who have chronic bilirubin encephalopathy demonstrate hypotonia, active deep tendon reflexes, a persistent tonic neck reflex and delayed motor development. After 12 months of age, the characteristic features of chronic kernicterus become apparent. These include extrapyramidal movement disorders, gaze disturbances and auditory dysfunction. Mental retardation occurs in a minority of patients.Return to top of page