Kernicterus

What is kernicterus?

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 the brain tissues. This causes permanent brain damage.

Kernicterus may be prevented by treating jaundice early before it gets severe.

What causes kernicterus?

Kernicterus is caused by a high level of bilirubin in a baby's blood. If left untreated, the bilirubin can then spread into the brain, where it causes long-term damage.

A low-level buildup of bilirubin is normal. This is called mild jaundice, and it gives a newborn a slightly yellowish tint to the skin and sometimes the eyes.

Normally, extra bilirubin is removed from the bloodstream by the liver and kidneys, and it leaves the body in urine and stool. During pregnancy, the mother's body removes the extra bilirubin for the baby. After birth, it takes a few days for the newborn's liver to get good at removing bilirubin from the blood. If you feed your baby every 1 to 3 hours, mild jaundice will usually go away on its own after a few days. But if your baby has any signs of jaundice, you and your doctor will need to watch him or her closely.

If jaundice continues to get worse and is not treated, bilirubin in the blood can build up to a high level. This is when kernicterus becomes a concern. It may be that some babies have health problems that make them more likely to have bilirubin levels that climb to high levels. For example, hemolytic disease, in which a mother's Rh blood factor is not compatible with her baby's, can make a baby produce more bilirubin than normal. Intestinal blockages can make it harder for a baby to remove bilirubin.

Keep in mind that in breast-fed infants, mild jaundice may last for 2 to 3 weeks or longer. In formula-fed infants, most jaundice goes away by 2 weeks of age. As long as you are feeding your baby every 1 to 3 hours, symptoms are not getting worse, and you go to all well baby visits, your baby will most likely be fine and not need treatment for mild jaundice.

What are the symptoms?

Kernicterus has likely already started if a baby has certain symptoms, including:

• Extreme sleepiness and lethargy. This means a baby is difficult to wake up from sleep 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 eat well, does not respond to touching or does not startle from sudden movements, and never seems to fully wake up.
• A very high-pitched cry that does not sound normal.
• Poor muscle tone. The baby may seem "floppy" and weak. Sometimes this is followed by periods when the baby's muscles flex in a way that is not normal. The baby may be stiff and arch his or her back and head.
• A fever that occurs along with any of these other symptoms.

The lifelong damage from kernicterus may cause long-term:

• Movement problems. A baby may develop slow and uncontrolled movements or random, jerky movements.
• Hearing loss or deafness. Some babies may seem to have normal hearing, but they develop a problem processing sounds. This is called auditory neuropathy or auditory dyssynchrony.
• Learning problems and other developmental disabilities.
• Problems moving the eyes, especially looking upward.

Kernicterus may cause stains on the outside (enamel) of a child's baby teeth (primary teeth).

How is kernicterus diagnosed?

Your doctor diagnoses kernicterus through a physical exam and knowledge of your child's history of symptoms. Blood tests to measure your baby's bilirubin levels are also done.

Once a baby has kernicterus, brain damage has already occurred. For this reason, it is important to follow and treat jaundice before bilirubin levels get too high.

Can kernicterus be prevented?

You may be able to help prevent kernicterus by being aware of the symptoms of jaundice and making sure your baby gets testing and treatment when needed.

• If your baby is still in the hospital and has signs of jaundice, your doctor will perform a simple blood test that measures the bilirubin level. A baby with a bilirubin level that requires treatment will have light therapy (phototherapy). This is usually given in the hospital. In very mild cases, you may treat your baby at home using lights the doctor gives you. Do not be alarmed if your baby has to have phototherapy; it does not mean that he or she is in danger of having brain damage. Doctors use this therapy to help prevent bilirubin from getting to a dangerous level.
• Feed your baby at least every 1 to 3 hours during the first week or two. This helps keep bilirubin moving out of the body through urine and stool.
• Set up a well-baby appointment with your doctor before you leave the hospital. The American Academy of Pediatrics (AAP) recommends that the first follow-up visit occur when your baby is 5 days old.¹ Jaundice is usually at its worst around day 5. This visit is important for your doctor to see if your baby has jaundice that is of any concern.
• Call your doctor if you think that your baby's skin on the tummy, arms, or legs is getting yellow or that yellowing on the face is getting worse. Also look for yellowing in the whites of your baby’s eyes. Get medical help right away if your baby is jaundiced and is hard to wake, acts very fussy, or is not feeding well.
• Talk to your doctor about what makes your baby more likely to get kernicterus, such as:
  • Being born early (more than 2 weeks before the due date).
  • Having jaundice in the first 24 hours after birth.
  • Having problems with breast-feeding.
  • Having bruises or bleeding on the head from a difficult birth.
  • Having an older brother or sister who received light therapy for jaundice.

How is it treated?

Quick treatment may help prevent further brain damage. Treatment may start with light therapy and fluids given through a needle into a vein (intravenous fluid replacement). Sometimes a baby may also have a tube placed down his or her throat or into the stomach for feeding with a special type of formula. A baby will also have a blood type test so that he or she can quickly get a blood transfusion if it is needed. A blood transfusion may be given to help remove extra bilirubin from the baby's blood.

Long-term treatment for brain damage will depend on a child's specific problems. Typical treatment includes physical therapy, speech therapy, and special education.

• Jaundice in Newborns (Hyperbilirubinemia)

Citations

1. American Academy of Pediatrics (2004). Management of hyperbilirubinemia in the newborn infant 35 or more weeks of gestation. Pediatrics, 114(1): 297–316.

Other Works Consulted

• Stevenson DK, Madan A (2003). Jaundice in the newborn section of Newborn infant. In CD Rudolph, AM Rudolph, eds., Rudolph's Pediatrics, 21st ed., pp. 164–169. New York: McGraw-Hill.