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Kernicterus

Definition

Kernicterus is a rare neurological condition that occurs in some newborns with severe jaundice.

See also: Newborn jaundice

Alternative Names

Bilirubin encephalopathy

Causes, incidence, and risk factors

Kernicterus is caused by very high levels of bilirubin. Bilirubin is a yellow pigment that is created in the body during the normal recycling of old red blood cells. High levels of bilirubin in the body can cause the skin to look yellow (which is called jaundice).

In some cases when there are extremely high levels of bilirubin in the body or the baby is extremely ill, the substance will move out of the blood and collect in the brain tissue. This can lead to serious neurological complications, including brain damage.

Kernicterus usually develops in the first week of life, but may be seen up until the third week. Newborns with Rh hemolytic disease that leads to hydrops fetalis are at high risk for severe jaundice that leads to this condition. However, kernicterus has been seen in apparently healthy babies.

Symptoms

The symptoms depend on the stage of kernicterus.

Early stage:

• Extreme jaundice
• Absent startle reflex
• Poor breast-feeding or sucking
• Extreme sleepiness (lethargy)

Mid stage:

• High-pitched cry
• Arched back with neck hyperextended backwards
• Bulging fontanel (soft spot)
• Seizures

Late stage (full neurological syndrome):

• High-frequency hearing loss
• Mental retardation
• Muscle rigidity
• Speech difficulties
• Seizures
• Movement disorder

Signs and tests

A blood test will show a high bilirubin level (greater than 20-25 mg/dL).

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

Treatment

• Phototherapy
• Exchange transfusion (may require multiple exchanges)

Treatment depends on how old the baby is (in hours) and whether the baby has any risk factors (such as prematurity).

Expectations (prognosis)

Kernicterus represents an extreme condition caused by hemolysis. The outcome is guarded. Many infants with late stage neurological syndrome die.

Complications

• Permanent brain damage
• Death

Calling your health care provider

Seek immediate medical help if your baby has signs of this condition.

Prevention

Early diagnosis and treatment of jaundice or conditions that lead to jaundice may help prevent this complication. The American Academy of Pediatrics recommends that infants with the first signs of jaundice have their bilirubin level measured within 24 hours. If the level is high, the infant should be screened for diseases that involve the destruction of red blood cells (hemolysis).

The association also recommends that all newborns have a follow-up appointment within 2 to 3 days after leaving the hospital. This is particularly important for premature or near-term babies.

References

American Academy of Pediatrics, Subcommittee on Neonatal Hyperbilirubinemia: Neonatal jaundice and kernicterus. Pediatrics. 2001;108:763.

American Academy of Pediatrics, Subcommittee on Hyperbilirubinemia Management of hyperbilirubinemia in the newborn infant 35 or more weeks of gestation. Pediatrics. 2004;114: 297-316.

In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 102.