What is kernicterus?
Jaundice in newborns is yellowing of the skin due to excessive bilirubin.
- Kernicterus is a type of brain damage due to excessive bilirubin in the blood.
- Signs and symptoms of jaundice include skin yellowing of the face, then chest, abdomen and extremities; the whites of the eyes may become yellowish.
- Contact your baby's doctor if the skin color becomes yellowish or orange colored, if the baby will not sleep, will not wake up easily, is very fussy or decreases its urine and fecal output.
- Emergency medical care should be sought if the baby is constantly crying (especially at a high pitch), has an arched body or has either a stiff or limp (floppy) body, and may have odd eye movements.
- Jaundice can be diagnosed by measuring bilirubin in the blood.
- Jaundice is treated by exposing the baby to special lights (the baby should not be placed in the sunlight); some may require more milk intake and a few may need a blood exchange transfusion.
- Risk factors for jaundice are common (about 60% of all babies have jaundice); preterm birth, dark skin color, East Asian or Mediterranean Descent, feeding difficulties, jaundice in siblings, bruising, or in babies whose mothers that have O blood type or are Rh negative.
- Your baby should be checked for jaundice in the hospital and again 48 hours after leaving the hospital.
- If your baby has jaundice, follow the instructions of your doctor for treatment and follow-up.
- If your baby is affected by kernicterus, there are local and national groups that may help you address the special needs for your child.
What is jaundice in newborns?
Jaundice is the yellow color seen in the skin of many newborns. Jaundice happens when a chemical called bilirubin builds up in the baby's blood. During pregnancy, the mother's liver removes bilirubin for the baby, but after birth the baby's liver must remove the bilirubin. In some babies, the liver might not be developed enough to efficiently get rid of bilirubin. When too much bilirubin builds up in a new baby's body, the skin and whites of the eyes might look yellow. This yellow coloring is called jaundice.
What is kernicterus?
When severe jaundice goes untreated for too long, it can cause a condition called kernicterus. Kernicterus is a type of brain damage that can result from high levels of bilirubin in a baby's blood. It can cause athetoid cerebral palsy and hearing loss. Kernicterus also causes problems with vision and teeth and sometimes can cause intellectual disabilities. Early detection and management of jaundice can prevent kernicterus.
What are the symptoms for kernicterus?
Signs of Jaundice can appear within the first few days of a newborn’s life. Jaundice causes the baby’s skin and whites of the eyes to turn a yellowish color. Kernicterus symptoms are more severe.
Babies with kernicterus are also lethargic. This means they are unusually sleepy. All babies sleep a lot, but lethargic babies sleep even more than is typical and are very hard to wake up. When they do wake up, they often fall right back to sleep.
Other symptoms of kernicterus include:
- high-pitched crying
- decreased appetite and less feeding than usual
- inconsolable crying
- floppy or limp body
- missing reflexes
- arching of the head and heels back, like a bow
- uncontrollable movements
- unusual eye movements
- lack of wet or dirty diapers
If you notice these symptoms, see a doctor or take your baby to the hospital right away.
What are the causes for kernicterus?
Kernicterus is caused by severe jaundice that isn’t treated. Jaundice is a common problem in newborns. It happens because a newborn’s liver can’t process bilirubin quickly enough. Bilirubin builds up in the baby’s bloodstream as a result.
There are two types of bilirubin in the body:
- Unconjugated bilirubin: This type of bilirubin travels from your bloodstream to your liver. It’s not water-soluble, meaning it doesn’t dissolve in water, so it can build up in your body’s tissues.
- Conjugated bilirubin: This is converted from unconjugated bilirubin in your liver. Conjugated bilirubin is water-soluble, so it can be removed from your body through your intestines.
If unconjugated bilirubin isn’t converted in the liver, it can build up in the baby’s body. When the level of unconjugated bilirubin gets very high, it can move out of the blood and into the brain tissue. Unconjugated bilirubin can lead to kernicterus if something causes it to build up. Conjugated bilirubin does not cross from the blood into the brain and can usually be removed from your body. Therefore, conjugated bilirubin doesn’t lead to kernicterus.
There are several potential causes that can lead to unconjugated bilirubin building up:
Rh disease or ABO incompatibility
Sometimes the baby’s and mother’s blood types are not compatible. If a mother is Rh-negative, it means her red blood cells don’t have a certain type of protein attached to them. It’s possible for her baby to have a different Rh factor than her. If her baby is Rh-positive, it means they do have that protein attached to their red blood cells. This is known as Rh incompatibility.
In Rh incompatibility, some of the fetus’ red blood cells can cross the placenta and get into the mother’s bloodstream. The mother’s immune system recognizes these cells as foreign. It produces proteins called antibodies that attack the baby’s red blood cells. The mother’s antibodies can then get into the baby’s body through the placenta and destroy the baby’s red blood cells.
As these blood cells are destroyed, the baby’s bilirubin levels rise. After the baby is born, bilirubin builds up in the bloodstream and brain. Rh disease is rare today, because mothers can be treated for it during pregnancy.
A similar, but less severe condition can sometimes occur when a mother has type O blood and her baby has a different type (ABO incompatibility). This is still fairly common. Though these babies are also at higher risk for kernicterus, it can almost always be prevented with proper monitoring and early treatment if necessary.
Babies with this inherited condition lack an enzyme needed to convert unconjugated bilirubin to conjugated bilirubin for removal. As a result, high levels of bilirubin build up in their blood.
Kernicterus and sulfonamides
Certain drugs — particularly antibiotics — have also been linked to kernicterus. Sulfonamides (also called sulfa drugs) are a group of antibiotics that kill bacteria. One common antibiotic combines the sulfonamide sulfamethoxazole with trimethoprim (SMX-TMP) to treat bacterial infections. Studies have raised concerns that sulfonamides might increase the risk for kernicterus.
Unconjugated bilirubin normally travels through the bloodstream to the liver bound to the protein albumin. In the liver, it’s converted to conjugated bilirubin so it can be removed from the body. Sulfonamides may unbind bilirubin from albumin, which increases blood levels of bilirubin. The unbound bilirubin can cross into the brain and cause kernicterus.
What are the treatments for kernicterus?
Mild infant jaundice often disappears on its own within two or three weeks. For moderate or severe jaundice, your baby may need to stay longer in the newborn nursery or be readmitted to the hospital.
Treatments to lower the level of bilirubin in your baby's blood may include:
- Enhanced nutrition. To prevent weight loss, your doctor may recommend more-frequent feeding or supplementation to ensure that your baby receives adequate nutrition.
- Light therapy (phototherapy). Your baby may be placed under a special lamp that emits light in the blue-green spectrum. The light changes the shape and structure of bilirubin molecules in such a way that they can be excreted in both the urine and stool. During treatment, your baby will wear only a diaper and protective eye patches. Light therapy may be supplemented with the use of a light-emitting pad or mattress.
- Intravenous immunoglobulin (IVIg). Jaundice may be related to blood type differences between mother and baby. This condition results in the baby carrying antibodies from the mother that contribute to the rapid breakdown of the baby's red blood cells. Intravenous transfusion of an immunoglobulin — a blood protein that can reduce levels of antibodies — may decrease jaundice and lessen the need for an exchange transfusion, although results are not conclusive.
- Exchange transfusion. Rarely, when severe jaundice doesn't respond to other treatments, a baby may need an exchange transfusion of blood. This involves repeatedly withdrawing small amounts of blood and replacing it with donor blood, thereby diluting the bilirubin and maternal antibodies — a procedure that's performed in a newborn intensive care unit.
What are the risk factors for kernicterus?
Babies are more likely to get severe jaundice and kernicterus if they:
- Were born prematurely. When babies are born before 37 weeks, their livers are even less well developed and will take longer to effectively remove bilirubin.
- Don’t feed well. Bilirubin is removed in stool. Poor feeding prevents babies from making enough dirty diapers.
- Have a parent or sibling who had jaundice as an infant. This condition can run in families. It may be linked to certain inherited disorders, such as G6PD deficiency, which causes red blood cells to break down too early.
- Were born to a mother with type O or Rh-negative blood type. Moms with these blood types sometimes give birth to babies who have high bilirubin levels.
Is there a cure/medications for kernicterus?
Once the symptoms of kernicterus appear, brain damage has already begun. Treatment can stop but not reverse this damage. That’s why it’s important to monitor newborns for high bilirubin levels — especially if they’re at risk — and treat them quickly.