Kernicterus

Aka: Kernicterus, Bilirubin Toxicity, Bilirubin Encephalopathy, Acute Bilirubin Encephalopathy, Chronic Bilirubin Encephalopathy

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II. Epidemiology: Incidence

  1. Acute Bilirubin Encephalopathy: 1 infant in 10,000 (Canada)
    1. Progresses to Kernicterus in 5% of infants
  2. Chronic Bilirubin Encephalopathy (Kernicterus): 1 infant in 100,000 (U.S.)
    1. More common in poorer countries

III. Risk Factors

  1. See Nonphysiologic Neonatal Jaundice
  2. Severe Hyperbilirubinemia (>20 mg/dl)
    1. Hyperbilirubinemia alone does not predict Bilirubin Encephalopathy
    2. Conditions that increase Bilirubin crossing the blood brain barrier increase the risk of encephalopathy and Kernicterus
    3. For healthy infants at term with Serum Bilirubin >30 mg/dl, only 5% develop Bilirubin Encephalopathy
    4. Gamaleldin (2011) Pediatrics 128(4): e925-31 [PubMed]
  3. Most common risks
    1. Earlier Gestational age <38 weeks (prematurity)
      1. Risk increase as Gestational age decreases
    2. Hemolysis
      1. Hemolytic Disease of the Newborn (due to Rh Sensitization)
      2. G6PD Deficiency
      3. Less common hemolytic conditions (e.g. Hereditary Spherocytosis, pyruvate kinase deficiency)
  4. Other risks
    1. Acidosis
    2. Acute clinical instability (prior 24 hours)
    3. Asphyxia
    4. Sepsis
    5. Serum Albumin <3 g/dl (30 g/L)

IV. Pathophysiology

  1. Unconjugated Bilirubin (indirect) elevation
  2. Total Bilirubin > 25 to 30 mg/dl
  3. Bilirubin is neurotoxic at high serum levels (necroses Neurons)
    1. Basal Ganglia
    2. Globus Pallidus
    3. Putamen
    4. Caudate nuclei

V. Findings: Symptoms and Signs

  1. Stage 1: Early Acute Bilirubin Encephalopathy
    1. Moro Reflex diminished
    2. Hyperreflexia
    3. Muscle tone diminished (hypotonia)
    4. Lethargy and Sleepiness
    5. Poor feeding
    6. Vomiting
  2. Stage 2: Intermediate Acute Bilirubin Encephalopathy (High mortality in this stage)
    1. High pitched cry
    2. Opisthotonus
    3. Seizure
    4. Stupor
    5. Irritability
    6. Fever
    7. Rigidity (hypertonia)
    8. Arched neck and back
    9. Oculogyric Crisis
    10. Upward gaze paralyzed
  3. Stage 3: Advanced Acute Bilirubin Encephalopathy
    1. Spasticity (decreases at 1 week of age)
    2. Upper extremity pronator spasm
    3. Apnea
    4. Coma
    5. Inability to feed
  4. Stage 4: Kernicterus (Chronic Bilirubin Encephalopathy with Residual deficits)
    1. Spasticity
    2. Severe athetoid Cerebral Palsy
    3. High frequency Hearing Loss or Deafness
    4. Mild Mental Retardation
    5. Upward Gaze Paralysis
    6. Dental dysplasia

VI. Management

  1. See Nonphysiologic Neonatal Jaundice

VII. Prognosis

  1. Significant mortality and morbidity
  2. Developmental follow-up is indicated for severe Hyperbilirubinemia

VIII. Complications

  1. Hearing Loss
  2. Cerebral Palsy
  3. Gaze Paralysis
  4. Dental Dysplasia
  5. Developmental Disability

IX. Prevention

  1. Early identification and management of nonphysiologic Newborn Jaundice
  2. Early identification of G6PD Deficiency (present in up to 10% of african american males)
    1. Absent from most U.S. Newborn Screens
  3. Prevent Hemolytic Disease of the Newborn (Erythroblastosis Fetalis)
    1. RhoGAM is given during pregnancy to prevent Rh Sensitization

X. References

  1. Harris (2001) Pediatrics 107(5):1075-80 [PubMed]
  2. Par (2023) Am Fam Physician 107(5): 525-34 [PubMed]
  3. Muchowski (2014) Am Fam Physician 89(11): 873-8 [PubMed]

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