1. General Comments

This disorder involves yellow staining of selected grey matter structures by unconjugated bilirubin. Kernicterus is the major problem which exemplifies the toxic disorders of the newborn. A number of factors operate to produce devastation of the nervous system of the immature infant.

2. Pathogenesis

The main source of increased bilirubin levels is hemolytic disease, but sepsis is also a cause. In the premature infant, relatively low levels of bilirubin can damage the nervous system, especially if the infant has very low albumin levels. Besides the presence of hypoalbuminemia, other insults can contribute to toxicity of low levels of bilirubin, e.g. drugs which may compete with albumin binding sites, anoxia (which increases the permeability of the blood brain barrier and leads to acidosis), and acidosis (which impairs bilirubin conjugation in the liver)

3. Pathological Changes

The most consistently affected CNS regions are the globus pallidus, subthalamic nucleus and hippocampus. Other regions often affected include dentate nucleus, inferior olivary nucleus, cranial nerve nuclei, cerebellar vermis and flocculus, putamen, and thalamus. Microscopic changes include loss of neurons, neuronal shrinkage, capillary prominence and gliosis.

This coronal section shows yellow discoloration of subcortical gray structures, typical in kernicterus.

This section of medulla shows yellow discoloration in the inferior olive.