Kernicterus in newborns is a condition that is characterized by jaundice, which is the yellowish discoloration of the eyes and the skin. It is due to high bilirubin levels. If untreated, severe jaundice may cause brain damage (1).
The condition of kernicterus is common in infants. It is also called bilirubin-induced neurological damage or bilirubin encephalopathy. Early detection and treatment of jaundice could prevent kernicterus and the serious complications that follow (2).
How Does Jaundice Cause Kernicterus?
The natural breakdown of the body’s red blood cells forms a compound called bilirubin (3). The liver processes bilirubin and the compound is excreted through urine and stool eventually. Babies have excess bilirubin since their red blood cells disintegrate faster than their livers can’t process bilirubin, causing jaundice. Jaundice leads to kernicterus when the total serum bilirubin level exceeds 25mg/dL.
Untreated jaundice may lead to kernicterus in two to five days after birth. Infants with a total serum bilirubin level less than 25mg/dL may also develop kernicterus. About one in seven infants with bilirubin levels higher than 30mg/dL will develop kernicterus (2).
Recent medical advancements have made kernicterus cases rarer than before, especially in some countries. For instance, according to the NHS, kernicterus affects about 1 in 100,000 babies in the UK (4) (5).
Symptoms Of Kernicterus In Newborn Babies
- Poor feeding
- High-pitched cry
- Apnea (pauses in breathing)
- Floppy muscles (muscle hypotonia)
- Absence of certain primitive reflexes
As the disease progresses, there is an excess accumulation of bilirubin in the brain, causing tissue damage. It could lead to the following severe symptoms (5).
- Bulging soft spot
- Hearing loss
- Respiratory distress
- Excessive muscle stiffness
- Problems with body movement and control
- Arching of the back and neck
Risk Factors For Kernicterus
- Premature birth: Babies born before 37 weeks of gestation may not have fully developed livers. The immature livers may be unable to remove excess bilirubin efficiently.
- Blood type: Babies of women with O blood type or Rh-negative blood factors are at a higher risk of having excessive bilirubin.
- Blood group incompatibility: If the baby and mother have different blood groups, the newborn’s blood cells could be damaged by maternal antibodies. Rapid breakdown of red blood cells could lead to excess bilirubin. This condition is known as hemolytic disease.
- Bruising during birth: A large amount of bruising during birth increases the breakdown of the red blood cells, contributing to the increasing bilirubin levels.
- Family history: The parents may pass certain genetic anomalies, leading to disorders that cause the breakdown of the baby’s red blood cells.
Diagnosis Of Kernicterus In Babies
The doctor may check for the presence of kernicterus periodically if the baby has been diagnosed with jaundice already. The following tests help in knowing if the bilirubin levels are suggestive of kernicterus (4).
- Physical examination: Check for the signs and symptoms, such as abnormal cry and poor primitive reflexes, which are suggestive of brain damage due to kernicterus.
- Light meter test: A doctor or nurse will place a light meter on the baby’s head to determine the transcutaneous bilirubin (TcB) level. If the reading is high, a blood test may be advised to determine kernicterus.
- Blood test: The nurse will draw a blood sample from the baby’s heel to check for the total serum bilirubin (TSB) levels. If the TSB levels are high, kernicterus is confirmed.
Treatment For Kernicterus In Babies
Treatment is decided on factors, such as the baby’s age in hours, baby’s gestational age, symptoms, and bilirubin levels. Once jaundice progresses to kernicterus, the baby experiences some brain damage already. Therefore, the treatment strategies focus on reducing the bilirubin level and preventing brain damage from progressing.
The following treatment methods could be considered to reduce bilirubin levels.
- Phototherapy: Intense fluorescent light is focused on the baby’s bare skin. The baby is dressed only in a diaper, and the eyes are shielded. The light helps in the decomposition and excretion of the excess bilirubin. During the treatment, the doctors test bilirubin levels every four to six hours until the bilirubin levels begin to drop and then every six to 12 hours until the treatment is complete.
- Transfusions: Blood transfusion is the second level of treatment for more severe cases. In this procedure, a little bit of blood is removed and is replaced with donor blood. Doctors test bilirubin levels two hours after the treatment and may perform another transfusion if the levels are not within the favorable range.
Complications Of Kernicterus
Babies with kernicterus may develop the following complications (5).
- Cerebral palsy
- Hearing loss
- Learning deficit
- Involuntary twitching of body parts
- Inability in maintaining normal eye movement
- Problems with teeth development
Prognosis Of Babies With Kernicterus
Kernicterus is a serious and life-threatening condition. The outcome usually depends on how soon the treatment was commenced. If kernicterus is diagnosed early and the treatment is started sooner, the neurological effects are minor. However, they may still have problems with motor skills as they grow in age (7). The baby’s healthcare provider may suggest long-term strategies to minimize complications or lasting effects of kernicterus. Kernicterus is rare as jaundice is usually caught early on during the hospital stay avoiding the progression to kernicterus.
Kernicterus is a severe condition, which occurs due to worsening jaundice. The condition can cause irreversible brain damage. Controlling jaundice and preventing the bilirubin levels from worsening is the best way to prevent kernicterus. Parents should stay alert to signs of jaundice to initiate early treatment, leading to better outcomes.
2. Dinesh K. Reddy and Shivlal Pandey, Kernicterus; National Center for Biotechnology Information
3. Newborn jaundice; NHS
4. Kernicterus in Newborn Babies; Birth Injury Help Center
5. Kernicterus; NHS
6. Kernicterus; National Organization for Rare Disorders
7. Kernicterus; Birth Injury Justice Center
8. Kernicterus; C.S. Mott Children’s Hospital