Kernicterus
Kernicterus is a rare, severe form of brain damage in infants caused by high levels of bilirubin (a yellow pigment) building up in a baby's blood and crossing into the brain. It is a rare but serious complication of severe, untreated jaundice and can lead to cerebral palsy, hearing loss, and other disabilities.
What Is Kernicterus?
Kernicterus (known medically as bilirubin encephalopathy) occurs when a baby has more bilirubin than their liver can clear. When bilirubin levels become very high and stay elevated (above 25 mg/dL), the pigment can deposit into deep areas of the brain (usually the basal ganglia, which is responsible for controlling movement).
When jaundice is left untreated, it can cause permanent brain damage and hearing loss and also lead to cerebral palsy. About 80% of newborns develop jaundice in the first week of life. However, most cases of jaundice are mild and temporary, and less than 10% of cases lead to kernicterus.
What Are the Signs and Symptoms of Kernicterus?
Parents often notice jaundice first as a yellowish color to the face, skin, or eyes. For children with darker skin, it's important for parents to monitor closely, as the yellow tint can be harder to spot. While newborn jaundice is common, it must be treated immediately to prevent kernicterus from developing.
Other signs of jaundice include:
- Jaundice spreading to the rest of the body, including the abdomen, arms, or legs
- Color that is deeper yellow or orange
- Baby who is very sleepy, hard to wake
- Problems breast- or bottle-feeding
- High-pitched or unusual cry
- Arching of the back or neck
- Weak muscle tone or "floppy" body
- Unusually low amount of wet and dirty diapers
Note: These signs do not mean that your baby definitely has kernicterus. However, if you notice any of these signs, contact your pediatrician or go to urgent care immediately to get treatment for your child.
What Causes Kernicterus?
The main cause of kernicterus is high levels of bilirubin in the body that are left untreated. Excess bilirubin can deposit itself into vulnerable areas of the brain and cause damage.
Also, since baby's livers are not fully developed, they are unable to effectively filter out and remove as much bilirubin as waste through their stool. Anything that significantly raises bilirubin or delays treatment can increase risk.
There are two main types of bilirubin in the body:
- Conjugated: Bilirubin processed by the liver, making it water-soluble so the body can excrete it through the intestines.
- Unconjugated: Bilirubin that is not water-soluble and can spread to other areas of the body, including the basal ganglia of the brain. Unconjugated bilirubin is most often responsible for causing severe jaundice and kernicterus.
How Is Kernicterus Diagnosed?
Doctors will diagnose kernicterus in multiple ways, including bilirubin levels, risk factors, and neurologic signs. Typical diagnosis steps include:
- Reviewing bilirubin levels over time (total and direct bilirubin)
- Physical and neurologic exams to look for signs like abnormal tone, poor feeding, or arching
- Hearing tests such as auditory brainstem response (ABR) as the child grows
- Imaging studies, usually MRI, which show patterns of bilirubin injury in areas of the brain such as the basal ganglia
Doctors will check for jaundice every 8-12 hours during the first 48 hours after birth. If your baby has increased risk factors, they may check every 4-6 hours. Parents can also monitor their child's bilirubin levels at home by placing a light meter on the baby's head, which can determine how much bilirubin is in the skin.
What Are the Risk Factors for Kernicterus?
Since newborn jaundice is so common, any baby is at risk of potentially developing kernicterus. However, certain risk factors increase the likelihood, such as:
- Premature or late preterm babies: Premature babies (before 38 weeks) have immature livers and are more likely to have severe jaundice and neurologic complications.
- Bruising or cephalohematoma from birth trauma: Large bruises or scalp hematomas break down into bilirubin and can cause high levels faster.
- Babies with darker skin: In babies who have darker skin, the yellow tone of jaundice can be more difficult to spot. Checking under the lips or gums can make it easier to identify jaundice.
- Sibling with jaundice: If the mother previously gave birth to another child who had jaundice and/or needed phototherapy or plasma transfusion, the risk also increases.
- Difficulty feeding or dehydration: Babies who are not feeding well (including not latching properly) or are losing too much weight pass fewer stools. This causes bilirubin to not be cleared efficiently and can rise to harmful levels.
- Blood type and Rh incompatibility: Mothers who have an O or Rh negative blood type are more likely to have babies with higher bilirubin levels.
- East Asian or Mediterranean descent: Jaundice is more common in East Asian and Mediterranean families due to a genetic condition called the G6PD deficiency. This deficiency causes red blood cells to break down faster than they are regenerated.
Any baby with noticeable jaundice, feeding problems, or other risk factors should have their bilirubin levels checked and re-checked during follow-ups. Catching jaundice before it develops into kernicterus is important so that treatment can be started to prevent permanent brain damage.
How Is Kernicterus Treated?
Kernicterus is almost entirely avoidable if jaundice is recognized and treated early. If bilirubin levels start to rise, doctors use tests and risk charts such as the AAP hyperbilirubinemia guidelines to decide when and what type of treatment is needed.
The most common treatments include:
- Phototherapy: Blue light therapy converts bilirubin into forms the body can excrete. The baby will either be placed directly under the light or lie on top of a blanket emitting blue light until bilirubin levels decrease to a safe amount.
- Intravenous fluids and improved feeding: Making sure the baby gets enough nutrition so that they start to produce more wet diapers (usually six or more per day) is a good indication that they are recovering well. In more serious cases, IVs can help prevent dehydration and clears bilirubin faster.
- Plasma transfusion: In more severe cases, a portion of the baby's blood is replaced with healthy blood to quickly lower bilirubin levels. If needed, the doctor may perform another transfusion until bilirubin levels are lowered to safe levels.
The most important step to take is managing jaundice early before severe brain damage occurs. Once kernicterus has caused permanent brain damage, treatment will focus on support, rehabilitation, and managing symptoms with the help of:
- Physical therapy: Helps to improve balance, coordination, and muscle tone, especially if a child suffers from cerebral palsy due to kernicterus.
- Speech therapy: Some children with kernicterus have difficulty speaking. Speech therapy exercises can help them to communicate better and improve confidence.
- Assistive devices: While tools like hearing aids or cochlear implants cannot cure hearing loss, they help to improve hearing ability, making daily communications easier.
What Are the Long-Term Effects of Kernicterus?
Depending on the severity of brain damage, different long-term disabilities may appear, such as:
- Muscle spasms, including cerebral palsy (most often dyskinetic cerebral palsy)
- Hearing loss, especially difficulty understanding speech in noise
- Vision problems, gaze abnormalities, or trouble looking up (gaze paresis)
- Speech and language delays
- Problems with balance and coordination
- Learning difficulties and developmental delays
- Convulsions or seizures (epilepsy)
Since the severity of kernicterus can range from mild functional challenges to severe disability, not every child will necessarily have all of these issues.
What Parts of the Brain Does Kernicterus Affect?
Depending on which are of the brain is damaged, symptoms and disabilities may be different. The most common areas of the brain affected are:
- Basal ganglia: Controls movement, coordination, and muscle tone. When this area is damaged, a child may develop stiff/floppy muscles, unusual postures, twisting or writhing movements, as well as some types of cerebral palsy.
- Cerebellum: Fine-tunes balance and coordination. Injury here can make a child unsteady, clumsy, or shaky. They may have trouble with sitting, walking, hand-eye coordination, or performing precise tasks with their hands.
- Hippocampus: Responsible for forming and storing new memories. They may have learning difficulties or trouble remembering new information.
- Geniculate bodies: Processes sound and visual information. Damage here can cause hearing loss, difficulty processing sounds and visuals, and make language development more challenging.
- Cranial nerve nuclei: Controls functions like eye movements, facial muscles, swallowing, and hearing. Babies may have poor feeding, abnormal eye movements, and changes in facial expression.
Can Kernicterus Be Prevented?
In many cases, yes. The most common prevention strategies include:
- Routine bilirubin screening before hospital discharge
- Follow-up visits at 3-5 days old, when bilirubin levels peak
- Clear instructions for parents on what jaundice signs to watch for
- Rapid access to phototherapy and plasma transfusion
When Is Kernicterus Caused by Medical Negligence?
Because kernicterus is generally avoidable in most cases, doctors who fail to recognize signs of jaundice or allow it to spread without treatment may be considered medically negligent.
Medical negligence may be involved if:
- Doctors fail to measure bilirubin when a baby clearly appears to have jaundice
- The hospital discharges a high-risk newborn without arranging early follow-ups
- Ignoring bilirubin levels that already meet thresholds for treatment
- Delaying phototherapy or plasma transfusion despite dangerous levels of bilirubin
- Not educating parents about the warning signs or when to seek emergency care
If you suspect medical negligence may have contributed to your child's kernicterus, make sure to speak with your pediatric specialist and a birth injury lawyer or kernicterus attorney as soon as possible. They can help you to review medical records and give guidance on potential legal options you may have.
Kernicterus FAQs
Written and Medically Reviewed by:
Cerebral Palsy Hub Team
Cerebral Palsy Hub was founded to help support children and their families with cerebral palsy and to create a safe space for those affected. We strive to provide the most accurate, up-to-date information, and tools to help give your child the life they deserve.
Last Updated: December 28, 2025
