Kernicterus is a rare but preventable form of brain damage caused by a high buildup of bilirubin in a newborn’s blood. This condition occurs when severe newborn jaundice is not effectively treated, allowing bilirubin to cause permanent damage to the brain and central nervous system. This brain injury is also referred to as bilirubin encephalopathy.
The Link Between Jaundice and Kernicterus
Newborn jaundice is a common condition, causing a yellow discoloration of the skin and the whites of the eyes. This yellowing is caused by bilirubin, a pigment produced when the body breaks down old red blood cells. In newborns, the maturing liver sometimes cannot process and clear this substance from the bloodstream quickly enough, leading to a buildup of bilirubin.
This accumulation connects jaundice to kernicterus. Bilirubin in the blood exists in two forms: unconjugated and conjugated. The unconjugated form is not water-soluble and can build up in tissues; the liver converts it into the water-soluble conjugated form, which can then be excreted.
When these levels become excessive, typically above 25 mg/dL, bilirubin can cross the newborn’s still-developing blood-brain barrier. This protective layer is less effective in the first days of life. Once across this barrier, the unconjugated bilirubin deposits into the brain’s grey matter, leading to the brain injury known as kernicterus.
Identifying the Warning Signs
Parents and caregivers should be aware of the signs of severe jaundice that require a doctor’s attention. These include the baby’s skin taking on a deeper yellow or orange hue, difficulty in waking the baby for feedings, or if the baby is not feeding well. These symptoms suggest that bilirubin levels may be rising to a concerning level.
The progression from severe jaundice to the illness that causes kernicterus is marked by more alarming symptoms. A key sign is a change in the baby’s cry to a very high-pitched sound. The infant may also become limp and floppy, alternating with periods of stiffness and muscle spasms. These muscle spasms can cause a distinctive arching of the back and neck, a posture known as opisthotonos. Other serious indicators include a fever, unusual eye movements, and a diminished startle reflex. The appearance of any of these signs constitutes a medical emergency.
Medical Intervention and Prevention
Preventing kernicterus begins with monitoring all newborns for jaundice before they leave the hospital and during their first few weeks of life. Regular follow-up appointments with a pediatrician are a primary defense, as they allow for timely identification and management of rising bilirubin levels.
The standard treatment for elevated bilirubin is phototherapy. This involves placing the baby under special blue lights, which work by altering the structure of the bilirubin molecules in the skin. This change allows the bilirubin to be excreted in urine and stool without needing to be processed by the liver. The baby’s eyes are protected during this non-invasive procedure.
In rare cases where bilirubin levels are dangerously high and do not respond quickly enough to phototherapy, a more direct intervention is required. A procedure called an exchange transfusion may be performed. This involves slowly removing the baby’s blood and replacing it with fresh donor blood, which rapidly lowers the concentration of bilirubin in the bloodstream.
Long-Term Health Consequences
The brain damage from kernicterus is irreversible and leads to a range of lifelong health challenges, collectively known as chronic bilirubin encephalopathy. These outcomes result from bilirubin toxicity affecting specific areas of the brain that control movement, hearing, and other functions.
One of the most common outcomes is a form of cerebral palsy called athetoid cerebral palsy, which is characterized by uncontrolled and involuntary muscle movements. Children may experience slow, writhing movements or random, jerky motions. This impacts coordination and can affect the entire body.
Hearing problems are also a frequent consequence, ranging from partial hearing loss to complete deafness. Some individuals may develop a specific issue known as auditory neuropathy, where the ear detects sound normally but has a problem sending the sound signal to the brain. The condition can also cause problems with eye movements, particularly a persistent difficulty with looking upward, and can lead to improper development of tooth enamel.