Kernicterus is a rare but serious form of brain damage in newborns caused by severe jaundice. This condition develops when an excess of a substance called bilirubin builds up in the blood, crosses into the brain, and causes permanent damage. Kernicterus is largely preventable with early detection and treatment of high bilirubin levels.
The Link Between Jaundice and Kernicterus
Bilirubin is a yellow substance produced when the body breaks down old red blood cells. In newborns, the liver is often not mature enough to process bilirubin efficiently, leading to a temporary buildup in the blood. This buildup causes jaundice, a condition that gives the skin and whites of the eyes a yellowish tint. Jaundice is very common, affecting about 60% of newborns, and resolves on its own as the baby’s liver matures.
In some cases, bilirubin levels can rise to dangerously high levels, a condition known as severe hyperbilirubinemia. When these levels become excessive, the bilirubin can cross the blood-brain barrier, a protective layer that shields the brain from harmful substances. Once in the brain, bilirubin can damage nerve cells, leading to kernicterus. This progression makes monitoring a newborn’s bilirubin levels important.
Several factors can increase a newborn’s risk for severe jaundice, which can lead to kernicterus. These include:
- Premature birth (before 37 weeks), as the liver is less developed.
- Blood type incompatibilities between the mother and baby (such as Rh or ABO), which can increase bilirubin production.
- Significant bruising during birth, which releases more bilirubin into the bloodstream as it heals.
- Difficulty with feeding, leading to poor hydration and calorie intake needed to excrete bilirubin.
Identifying Kernicterus Symptoms
The initial signs of kernicterus can be subtle. Early symptoms often include extreme sleepiness or lethargy, making the baby difficult to wake for feedings. The baby may also have a poor appetite. Changes in muscle tone are another indicator, with the baby appearing either unusually floppy or stiff.
As bilirubin levels rise, the symptoms become more alarming. The baby may develop a high-pitched, inconsolable cry or arch their back and neck, a posture known as opisthotonus. Other later symptoms can include uncontrollable movements, fever, and seizures. If any of these symptoms are observed, it is a medical emergency, and the baby should be taken to a hospital immediately.
Medical Diagnosis and Intervention
When a baby shows signs of jaundice, a healthcare provider may use a non-invasive device to estimate the bilirubin level. The definitive diagnosis for high bilirubin levels is a blood test called a total serum bilirubin (TSB) test. This test measures the amount of bilirubin in the blood and helps the doctor determine if treatment is necessary. Monitoring is especially important for babies with known risk factors.
The primary treatment for high bilirubin levels is phototherapy. During this treatment, the baby is placed under special blue-green lights wearing only a diaper and eye protection. The light energy helps change the bilirubin molecules, making them easier for the body to excrete. This process lowers bilirubin levels and prevents them from causing brain damage.
In rare cases where bilirubin levels are extremely high or rise despite phototherapy, an exchange transfusion may be necessary. This procedure involves slowly removing the baby’s blood and replacing it with fresh donor blood or plasma. An exchange transfusion quickly lowers bilirubin by removing the excess amount and any antibodies causing the rapid breakdown of red blood cells.
Long-Term Health Outcomes
The brain damage caused by kernicterus is permanent and can lead to lifelong neurological conditions. One of the most common is athetoid cerebral palsy, which affects movement and muscle coordination, resulting in uncontrolled or jerky motions. This can impact fine motor skills, posture, and balance.
Hearing problems are also a frequent complication, ranging from partial hearing loss to complete deafness. Some individuals develop auditory neuropathy, where the ear detects sounds but the brain has difficulty interpreting them. Vision problems can also occur, particularly with eye movement, such as difficulty with upward gaze.
Kernicterus can also affect other areas of development, including the abnormal development of tooth enamel, causing teeth to be stained or poorly formed. While intelligence is often unaffected, some may experience learning disabilities or developmental delays.
Prevention and Monitoring
Preventing kernicterus begins with ensuring the newborn is feeding well. Frequent feeding, by breast or bottle, helps the baby stay hydrated and promotes regular bowel movements, which are the primary ways the body excretes bilirubin. If there are concerns about feeding, a lactation consultant or doctor can provide support.
Parents should monitor their baby for jaundice by checking the skin and eyes in natural light for yellowing. A simple way to check is to gently press on the baby’s nose or forehead; if the skin looks yellow when the pressure is released, it is a sign of jaundice. It is also important to attend all follow-up appointments after leaving the hospital, as this is when bilirubin levels often peak.
If jaundice appears to be worsening, or if the baby shows early symptoms like extreme sleepiness or poor feeding, contact a doctor immediately. Early detection and treatment of severe jaundice are the most effective ways to prevent kernicterus.