Kernicterus

Disease Description (Causes and Symptoms)

• Definition summary: Kernicterus is a condition in which unconjugated (indirect) bilirubin in the blood crosses the blood-brain barrier and accumulates in brain tissue (particularly the basal ganglia, brainstem, etc.), causing neurological damage.
• Pathophysiology: When indirect bilirubin increases due to hemolysis or impaired hepatobiliary excretion, free bilirubin that is not bound to albumin is produced. In immature newborns, in states with low blood albumin-binding capacity, or when blood-brain barrier permeability is increased, free bilirubin penetrates the brain and causes neurotoxicity.
• Main causes: Neonatal hemolytic disease (ABO or Rh incompatibility), inherited metabolic disorders, impaired liver function (congenital liver disease, infection), biliary obstruction, etc. In newborns, physiological jaundice and breastfeeding-related jaundice may also be causes.
• Representative symptoms (early → progressive):
  • Early: Restlessness, poor feeding, drowsiness (unresponsiveness), reduced responsiveness to stimuli
  • Progressive: Muscle atrophy/abnormal muscle tone (muscle rigidity or hypotonia), opisthotonus, loss of reflexes (such as the Moro reflex), seizures, high-pitched crying
  • Yellowing of the skin and sclera (beginning in the face and progressing to the trunk and extremities)
• Vulnerable groups: Premature infants (preterm), low-birth-weight infants, newborns with blood type incompatibility, patients with chronic/severe liver disease

Treatment Methods

• General principles: Lower serum total bilirubin, prevent penetration into the brain, and correct the underlying cause (hemolysis, infection, etc.).
• Phototherapy
  • Standard first-line treatment. Blue light (approximately 420–470 nm) is used to convert bilirubin into photoisomers and water-soluble forms, promoting excretion.
  • The duration varies by individual patient and is continued until the levels stabilize (usually several days). Effects are monitored through repeated measurements.
  • Precautions: Eye protection, monitoring of hydration and body temperature, and the possibility of dehydration and diarrhea.
• Exchange transfusion
  • Considered in severe hyperbilirubinemia (or when signs of acute bilirubin encephalopathy are present). As an emergency and invasive procedure, it may need to be performed immediately.
  • Complications: Electrolyte imbalance, infection, bleeding problems, transfusion reactions, etc.
• Drug treatment
  • IVIG (intravenous immunoglobulin): In antibody-mediated hemolytic disease (e.g., Rh/ABO hemolysis), it may help reduce hemolysis and suppress the rise in bilirubin.
  • Liver enzyme-inducing drugs such as phenobarbital may be considered in limited situations (slow effect).
• Supportive care
  • Adequate feeding and hydration, temperature management, treatment of infection, and correction of the underlying cause.
• Long-term follow-up and rehabilitation
  • If the patient survives, hearing tests (such as Auditory Brainstem Response), neurodevelopmental follow-up, and rehabilitation (such as physical therapy and speech therapy) are necessary.
• Precautions
  • In premature infants or certain situations, active treatment may be necessary even when the bilirubin risk level is low.
  • Because bilirubin may rebound after phototherapy or exchange transfusion, follow-up testing is important.

Checklist Before an Outpatient Visit (Useful Information and Questions for Preparation and Consultation)

• Items and information to prepare
  • Birth records: Birth weight, gestational age (term/preterm), and notable details of the delivery process
  • Blood types and antibody test results of the mother and baby (if possible)
  • Recent blood test results (total, direct, and indirect bilirubin levels, CBC, liver function tests, etc.)
  • History of previous treatments such as phototherapy and exchange transfusion
  • Feeding records (breast milk, formula, or mixed feeding), feeding frequency and amount, and the frequency and color of urine and stool
  • Records of symptom changes (feeding ability, sleep, crying pattern, seizures, etc.)
• Items to show the doctor during the consultation
  • Test results showing the recent bilirubin trend
  • The baby's weight change chart
• Example questions to check before the outpatient visit (including what to do in an emergency)
  • Is there difficulty breathing, seizures, persistent unresponsiveness, or severe drowsiness? (The emergency room is recommended.)
  • Is the jaundice rapidly spreading from the face to the body?
  • Has the feeding amount sharply decreased, or has the frequency of urination or bowel movements decreased?

Examples of General Questions to Ask the Doctor

• Is this baby's current bilirubin level at a dangerous level? What are the treatment criteria?
• What are the benefits and risks of the recommended treatment (phototherapy/exchange transfusion/IVIG)?
• What is the possibility of recurrence after treatment, and what is the schedule for follow-up tests?
• Can the baby be cared for at home during phototherapy? What special precautions should be taken?

Examples of Disease-Specific Questions

• My child is premature (or has a low birth weight). Even with the same bilirubin level, are the treatment criteria different from those for a full-term infant? How is the decision made?
• The child had seizures (or an abnormal response). When and how should hearing tests and neurodevelopmental follow-up be conducted after discharge?

Additional Information (Summary)

• Warning signs (an immediate emergency room visit is necessary): Repeated or persistent seizures, a severely comatose state/no response, difficulty breathing, or a rapid decrease in feeding.
• Prevention points: Bilirubin monitoring after birth (especially for high-risk groups), blood type and antibody testing, early and sufficient feeding, and timely application of phototherapy.