Kernicterus is a rare but serious complication of untreated jaundice in babies caused by excess bilirubin damaging the brain or central nervous system.

In newborn babies with very high levels of bilirubin in the blood (hyperbilirubinaemia), the bilirubin can cross the thin layer of tissue that separates the brain and the blood (the blood-brain barrier). The bilirubin can damage the brain and spinal cord, which can be life-threatening.

Brain damage caused by high levels of bilirubin is also called bilirubin encephalopathy.

Your baby may be at risk of developing kernicterus if:

• they have a very high level of bilirubin in their blood
• the level of bilirubin in their blood is rising rapidly
• they do not receive any treatment

Kernicterus is now extremely rare in the UK, affecting less than 1 in every 100,000 babies.

Initial symptoms of kernicterus in babies include:

• decreased awareness of the world around them – for example they may not make any reaction when you clap your hands in front of their face
• their muscles become unusually floppy like a rag doll (hypotonia)
• poor feeding

As kernicterus progresses, additional symptoms can include seizures (fits) and arching of the neck and/or spine.

Treatment for kernicterus involves using an exchange transfusion as used in the treatment of newborn jaundice.

If significant brain damage occurs before treatment, a child can develop serious and permanent problems, such as:

• cerebral palsy – a condition that that affect a child's movement and co-ordination
• hearing loss, which can range from mild to severe
• learning difficulties
• involuntary twitching of different parts of their body
• problems maintaining normal eye movements – people affected by kernicterus have a tendency to gaze upwards or from side to side rather than straight ahead
• the normal development of the teeth can be disrupted resulting in teeth that are misshapen, discoloured and vulnerable to tooth decay 

Blood

Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.

Brain

The brain controls thought, memory and emotion. It sends messages to the body controlling movement, speech and senses.