Is Kernicterus preventable?

Although kernicterus is almost always preventable, cases continue to occur.  Kernicterus is brain damage caused by the deposit of bilirubin in parts of the brain called the basal ganglia and the brain stem nuclei.

Kernicterus is a form of brain damage caused by excessive jaundice.  Jaundice is the discoloration of the skin and sclera of the eye, which occurs when bilirubin accumulates in the blood.  Jaundice occurs because red blood cells are being broken down too fast for the liver to process, because of disease of the liver or because of bile duct blockage.

The substance which causes jaundice, bilirubin, is so high that it can move out of the blood into brain tissue.  Bilirubin is one of the waste produces of red blood cells, and excessive levels of bilirubin stain the fatty tissues in the skin yellow.  Very high levels of bilirubin in the blood stream can cause permanent damage to certain areas of the brain of newborn infants known as kernicterus.  This can cause a characteristic form of cerebral palsy known as athetoid cerebral palsy.

In adults and most children, jaundice is harmless in and of itself.  But the tissues protecting the brain (the "brain-blood barrier") are immature in newborns.  In newborns, bilirubin penetrates the brain and literally stains the nerve bodies, causing irreversible brain damage.  Depending on the level of exposure, the effects range from unnoticeable to severe brain damage.

Nurseries should have established protocols for the assessment of jaundice.  In newborn infants, jaundice is usually first seen in the face and progresses to the legs and arms. A TSB (total serum bilirubin) blood test should be performed on every infant who is jaundiced in the first 24 hours after birth and all bilirubin levels should be interpreted according to the infant's age in hours.

Hyperbilirubemia, or excessive bilirubin in the blood stream, is a bilirubin concentration greater than 10 mg/dl (milligrams per deciliter) in premature newborns or greater than 15 mg/dl in full-term newborns.  Excessive accumulation of bilirubin, if untreated, can lead to kernicterus.  When the blood level of bilirubin is about 4 to 5 mg/dl, jaundice first becomes apparent and with increasing bilirubin levels, visible jaundice becomes more apparent in a head-to-toe direction.

If the total serum bilirubin (TSB) is at a level that is 25 mg/dl, it is a medical emergency and the infant should be admitted immediately and directed to a hospital service for intensive phototherapy and/or a blood transfusion.  Immediate blood transfusion is necessary for an infant who is jaundiced and shows the signs of the intermediate to advanced stages of acute bilirubin encephalopathy, even if the TSB is falling.

The main value of phototherapy is that it reduces the risk that TSB levels will reach a level at which a blood transfusion is necessary.  Phototherapy decreases bilirubin concentrations, thereby preventing elevated bilirubin levels that can cause permanent brain damage. In almost all cases, a blood transfusion is recommended only after phototherapy has failed to keep the TSB level below the blood transfusion level.

The goal of treatment for newborns with hyperbilirubinemia is to avoid bilirubin concentrations that may cause kernicterus.  Early detection and treatment of hyperbilirubinemia is critical for the prevention of kernicterus. The only way to ensure that your baby will not be harmed by bilirubin is to have the baby's bilirubin level measured and plotted on a nomogram.  Aggressive treatment of jaundice, including early phototherapy and blood transfusions in certain newborns wit elevated bilirubin levels, should consistently prevent kernicterus.