Jaundice and Bilirubin Encephalopathy ✅ Flashcards
Is jaundice common in the neonatal period?
Yes
What % of term infants develop jaundice in the first week?
60%
What % of preterm infants develop jaundice in the first week?
80%
What % of breastfed infants are still jaundiced at 1 month?
10%
Why is neonatal jaundice important?
- May indicate underlying disease
- Severe unconjugated hyperbilirubinaemia can lead to neonatal encephalopathy and long term neurodevelopmental problems
What underlying diseases might neonatal jaundice indicate?
- Infection
- Haemolytic anaemia
- Liver and metabolic disease
What terms are used to describe acute clinical CNS manifestations of bilirubin toxicity?
Acute bilirubin encephalopathy, or bilirubin-induced neurologic dysfunction (BIND)
What causes bilirubin encephalopathy?
Free bilirubin in the blood (the unconjugated fraction of bilirubin unbound to albumin)
What is meant by kernicterus?
The histological findings of bilirubin toxicity within the brain
What are the histological findings of bilirubin toxicity in the brain?
Staining and necrosis of neurons
What are the key areas involved in kernicterus?
- Basal ganglia, particularly the globes pallidus and subthalamic nuclei
- Nuclei of oculomotor, vestibular, and facial cranial nerves
- Cerebellar nuclei, particularly the dentate
- Anterior horn cells of the spinal cord
Is the cerebral cortex involved in kernicterus?
Usually spared
Is there good correlation between yellow staining and the distribution of neuronal necrosis?
Yes
What areas of involvement of kernicterus are more obvious clinically?
Brainstem nuclei and basal ganglia
What factors increase the risk of bilirubin toxicity?
- High levels of free bilirubin
- Disruption of integrity of blood-brain barrier
- Hypercapnia, hyperosmolality, acidosis
What can cause high levels of free bilirubin?
- Low albumin
- High bilirubin-albumin ratio
- Abnormal bilirubin-albumin binding
- Competitive displacement by certain drugs
What drugs can cause competitive displacement of bilirubin from albumin?
- Ceftriaxone
- Salicylates
- Ibuprofen
- Aminophylline
What can cause disruption of the integrity of the blood-brain barrier?
- Sepsis
- Meningitis
- Seizures
- Shock
- Hypoxia-ischaemia
What does the threshold when bilirubin toxicity occur depend on?
Co-existing risk factors
When is the risk of bilirubin toxicity increased?
- When serum bilirubin level is >340µmol/L in term infants
- Rate of rise of serum bilirubin >8.5µmol/L/hour
What is the mechanism of bilirubin toxicity?
Uncertain
What is thought to be true of the passage of bilirubin across the blood-brain barrier?
Thought to be a dynamic and potentially reversible process
Why does hypercapnia increase the risk of bilirubin toxicity?
It leads to vasodilation and increased cerebral blood flow and lower pH, therefore increasing both influx and efflux of free bilirubin across the blood brain barrier and resulting in high level but brief exposure
How does hyperosmolality affect the passage of bilirubin across the blood brain barrier?
It slows the efflux, but not the influx of bilirubin, so causes a longer low level exposure
What are the initial signs of acute bilirubin encephalopathy?
- Lethargy
- Hypotonia
- Decreased suck
What follows the initial signs of acute bilirubin encephalopathy?
An intermediate phase characterised by;
- Stupor
- Irritability
- Hypertonia
- High pitched cry
How does the hypertonia in the intermediate phase of acute bilirubin encephalopathy manifest?
Arching of the neck and the trunk (opisthonus)
What can the intermediate phase of acute bilirubin encephalopathy lead to without intervention?
- Coma
- Fever
- Apnoea
- Seizures
- Death
What can develop in survivors of advanced bilirubin encephalopathy?
The cardinal clinical features of kernicterus:
- Choreoathetoid CP
- Sensorineural deafness
- Gaze abnormality
- Dental enamel dysplasia
What is particularly affected in gaze abnormality caused by kernicterus?
Upwards gaze
