Introduction:
Kernicterus is a rare disorder that is caused due to elevated levels of bilirubin in the blood of the newborn. It is a sign of brain damage but reversible when treated early. Kernicterus is also called bilirubin encephalopathy, where the bilirubin levels are more than 25 mg / dL in the blood. The elevated bilirubin levels cross the blood-brain barrier and get deposited in the brain tissues, which leads to neurotoxicity. Treatment for kernicterus focuses on lowering the bilirubin levels in the blood and preventing further damage to the brain.
What Is Bilirubin?
Bilirubin is an orange-red substance formed from the byproducts of the breakdown of hemoglobin in red blood cells. They are excreted in the bile by the liver. If they are not eliminated, they get deposited in the body tissues.
Why Is This Common in Newborns?
In newborns, the liver is not fully developed to excrete the bilirubin from the body, so it gets accumulates in the tissues. It may result in the yellowing of the skin and sclera of the eyes resulting in jaundice. If this is not treated, it may cross the blood-brain barrier and get deposited in the brain tissues. This condition is called kernicterus. It may interfere with eyesight and may cause intellectual disabilities in some babies.
Who Coined the Term Kernicterus?
Although Hervieux first explained this medical condition in 1847, Schmorl coined the term kernicterus in 1903. He observed that several parts of the brain were affected by high bilirubin levels, including the basal ganglia, hippocampus, and cranial nerves.
What Are the Signs and Symptoms?
The symptoms are noticeable within a few days after birth. The clinical manifestations of kernicterus are:
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The skin, mucous membrane, and sclera of the eye appear yellow.
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The child seems very lethargic and drowsy.
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Fever.
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Poor feeding habits.
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High-pitched cry and is always fussy.
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Respiratory distress.
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Low muscle tone with muscle spasms.
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Convulsions and seizures.
When to Seek Medical Help?
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If the child is inconsolable with a faint cry.
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Strange eye movements with body stiffness.
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Presence of seizures.
What Are the Risk Factors?
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Preterm Infants: Babies born before 37 weeks of gestation are at high risk for jaundice and kernicterus as the liver is not fully developed.
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Poor Feeding Habits: Bilirubin is eliminated in the stools. Lack of appetite may result in fewer bowel movements, and therefore the bilirubin is not properly excreted from the body.
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Family History: If anyone in the family or the siblings of the baby has a history of neonatal jaundice, then there are high chance of the baby having jaundice. It is due to the deficiency of the enzyme G6PD (glucose-6-phosphate dehydrogenase) that runs in families.
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Rh-Negative Blood Type: If the mother is Rh-negative, then the baby will likely have higher bilirubin levels in the body than normal. This is due to increased red blood cell destruction resulting in increased byproducts (bilirubin).
What Are the Other Similar Conditions?
There are several other conditions that share symptoms similar to jaundice or kernicterus. The conditions are:
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Cerebral palsy.
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Neonatal sepsis.
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Traumatic head injuries.
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Hypoxia and ischemic brain damage.
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Endocrine disturbances such as cretinism and hypothyroidism.
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Bacterial meningitis.
How to Diagnose Kernicterus?
They are usually diagnosed soon after birth by a clinical examination. In most cases, there is a yellow discoloration of the skin, mucous membrane, and sclera of the eye (white portion of the eye). Other diagnostic tests required for establishing kernicterus are:
Laboratory Investigations:
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Total and Direct Bilirubin Test: It is a simple, noninvasive laboratory investigation that rules out elevated levels of bilirubin in the blood and detects any other liver diseases.
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Rh Incompatibility Test: The test is done to identify Rh incompatibility if the mother belongs to a negative blood group. It helps to prevent erythroblastosis fetalis. It is a medical condition where the red blood cells of the baby are entirely destroyed due to incompatible blood groups of the mother and baby.
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Reticulocyte Count: This test is helpful in assessing the hemolysis process. A higher reticulocyte count in the baby is indicative of an active hemolytic process.
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Lumbar Puncture: The cerebrospinal fluid is taken and cultured to detect any bacterial sepsis or meningitis.
Imaging Test:
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Chest X-rays: They help to detect the presence of sepsis in the baby.
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Computed Tomography and Magnetic Resonance Imaging of the Brain: They are generally not indicated as laboratory investigations provide adequate information. However, in some cases, if the other tests do not provide more details, then CT and MRI of the brain are advised.
How Is Kernicterus Treated?
The treatment of kernicterus focuses on two primary goals. They are:
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To reduce the bilirubin levels in the blood and to prevent neurotoxicity.
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To prevent the recurrence of high bilirubin levels.
The treatment protocols followed for kernicterus are:
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Transfusion Therapy: This is indicated when there is bilirubin encephalopathy and when the serum bilirubin levels are more than 20 to 25 mg/dL. It is a more effective method for removing the bilirubin in the blood of the baby. In this procedure, the blood is removed and replaced simultaneously with citrate-phosphate-dextrose obtained from the blood banks. This blood is free from bilirubin. Generally, blood should be ABO and Rh-compatible for blood transfusion. Although blood transfusions can cause infections, the risks are low nowadays with safety and preventive measures.
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Phototherapy: It is the first line of treatment done for jaundice. Phototherapy uses light energy for the conversion of the insoluble bilirubin molecules to water-soluble molecules so that they are easily excreted from the body. However, during phototherapy, special care should be taken for eye protection. The eyes are covered with a mask as the light can cause permanent damage to the retina of the eye.
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Intravenous Immunoglobulin: It is used in cases of immunological mediated conditions such as Rh-incompatibility or other blood group incompatibilities that cause neonatal jaundice. The intravenous immunoglobulin transfusion reduces the chances of blood transfusions in some cases.
What Is the Prognosis for Kernicterus?
The prognosis generally depends on the severity of the condition. However, early diagnosis and appropriate treatment can prevent permanent brain damage in the baby. Conversely, any delay in the diagnosis and treatment may cause neurologic impairments.
Conclusion:
Neonatal jaundice has become a common medical condition in newborns. Although it is common, it may result in serious conditions such as brain and other neurologic damage if they are untreated. Hence proper diagnosis and treatment are essential. As soon as kernicterus is suspected, treatment should be begun without any further delay to avoid unnecessary complications. Parents should be counseled on how to feed their babies and enhance breastfeeding practices. Regular follow-ups and medical examinations are mandatory within 48 to 72 hours after birth.
