Kernicterus is a very rare type of brain damage that occurs in a newborn with severe jaundice. It happens when a substance in the blood, called bilirubin, builds up to very high levels and spreads into brain tissues.

Kernicterus can cause long-term hearing loss, mental retardation, and behavior problems.

Kernicterus may be prevented by treating jaundice that is not getting better when it should be. Mild jaundice—a low level of bilirubin buildup—is common in newborns. Its main symptom is a yellowish tint to a baby's skin and sometimes eyes. Jaundice usually is at its worst about 5 days after birth. Most often, jaundice resolves on its own when caregivers feed the baby every 2 to 3 hours. But doctors and caregivers must keep a close eye on a baby with jaundice.

Babies who are at risk for severe jaundice will have a blood test to measure the blood bilirubin level. Doctors start treatment for babies whose bilirubin levels are higher than they should be.

Mild to moderate jaundice is easily treated with special lights called phototherapy. Usually, babies are treated with phototherapy at the hospital. Less often, a baby with mild jaundice may be treated at home with lights that a doctor provides. If bilirubin reaches a level where kernicterus is a concern, the baby may be given a blood transfusion.

Once symptoms of kernicterus are noticed, brain damage is already occurring. A baby with kernicterus is very sleepy and lethargic. This means that the baby is very difficult to wake up or can't be kept awake. But keep in mind that newborn babies sleep a lot. Lethargy in a newborn is easy to confuse with normal newborn behavior. A lethargic baby does not ever seem fully awake. He or she also does not eat well, does not respond to touching, or does not startle from sudden movements.

A baby with kernicterus usually also has a very high-pitched cry that does not sound normal. The baby has poor muscle tone. He or she may seem "floppy" and weak. Sometimes this floppiness will suddenly change to muscle stiffness and tension. During these periods, the baby may arch his or her back and head.

A fever that occurs along with these other symptoms is also a sign of kernicterus. A baby with signs of kernicterus needs emergency medical treatment to help prevent more brain damage.

Last Updated: May 27, 2008

Author: Debby Golonka, MPH

Medical Review: Michael J. Sexton, MD - Pediatrics & Thomas Emmett Francoeur, MDCM, CSPQ, FRCPC - Pediatrics

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