Hyperbilirubinemia with indirect bilirubin of 20mg% or more, irrespective of the causative factor, can produce neurological signs and symptoms in a newborn. In the case of a low birth weight infant, kernicterus may result from a lower level of bilirubin. The basal ganglia and other nuclear areas of the brain are the predominant sites of involvement.
The commonest cause of kernicterus is the hemolytic disease of the new born. But, conditions like Crigler-najjar syndrome (congenital glucornyl-transferase deficiency) can occasionally lead to this complication.
The earliest manifestations in a deeply jaundiced baby are sluggish or incomplete Moro reflex, and feeding difficulties. With progression of the disease, the infant develops hypotonia followed in a few days by rigidity. Hyperpyrexia and convulsions occur in severely affected babies.
Those who manage to survive are Left with sequelae of extra pyramidal involvement, deafness, mental retardation, etc.