Kernicterus
Kernicterus is a chronic neurological condition caused by the neurotoxic effects of bilirubin in the brain tissues of newborns. This occurs when bilirubin, a byproduct of red blood cell breakdown, is present at abnormally high levels in the newborn. Kernicterus can be prevented by treating jaundice, the term used to describe the clinical presentation of yellow skin and whites of the eye. Furthermore, risk factors for the development of this devastating neurological condition can be identified and should prompt close monitoring of total bilirubin levels in the serum of the infant who is at risk of developing one of the acute clinical phases of neurological damage that included bilirubin-induced neurological dysfunction syndrome.
Kernicterus is a relatively rare cause of severe lifelong disability in otherwise normal babies, but it can be prevented. Severe or extreme levels of bilirubin in the serum cause encephalopathy, and bilirubin has long been recognized as a neurotoxin that results in the death and destruction of brain cells.
Acute bilirubin encephalopathy
Acute bilirubin encephalopathy is characterized by increased bilirubin that has crossed the blood-brain barrier. When diagnosed clinically, the presentation of symptoms is broad and includes feeding problems, lethargy, hiccups or hypertonia, opisthotonos, fever, seizures, high-pitched crying, and spasmodic torticollis.
Acute bilirubin encephalopathy has three clinical phases, each with different characteristics. The first phase occurs a few days after birth and symptoms include stupor, hypotonia, and poor suction. The second phase is characterized by hypertonia, with bowing of the trunk (opisthotonos) or retrocolis, which is a bowing of the neck backwards. Babies who reach this stage develop chronic bilirubin encephalopathy. The third phase occurs after a week and the hypertonia disappears. There is stiffness of the muscles, paralysis of the upward gaze, periodic oculogyric crisis, and, in the terminal phase, irregular respiration is prominent. In this third phase, four percent of affected babies die.
Chronic Bilirubin Encephalopathy
Chronic bilirubin encephalopathy is also known as kernicterus. The term refers to lifelong disability resulting from bilirubin-induced neurological dysfunction. Kernicterus is characterized by a poor diet during the first year. A high-pitched cry is another characteristic of kernicterus.
Babies with kernicterus will be hypotonic but will retain good deep tendon reflexes. There is presence of a tonic neck reflex and a righting reflex. Motor skills are delayed and some children walk by age 5.
After the first year of life, clinical features that are prominent in children with chronic bilirubin encephalopathy include extrapyramidal disorders such as tremors, dysarthria, athetosis, and ballism. There is damage to the cochlear nuclei in the brainstem resulting in hearing loss, and there is usually limited upward gaze. Athetosis usually develops between 18 months and 8 years of age. Some children only experience hearing loss and have no other symptoms.
Imaging studies in the diagnosis of Kernicterus
When investigating kernicterus, in most cases there are elevated levels of serum bilirubin. The imaging studies that are most helpful are MRI. On MRI images, there is often an increased signal intensity in the globe pallus.
How common is Kernicterus?
In the United States, there is a voluntary registry of kernicterus, and 90 cases were reported during the period 1984-2001. Since not all cases are reported, the true incidence is unknown.
Kernicterus is preventable
Kernicterus is highly preventable when high-risk babies are closely monitored and aggressively treated. However, without treatment, elevated bilirubin jaundice can result in permanent brain damage, and some children can develop cerebral palsy, tooth enamel hypoplasia, and mental retardation as a result. Unfortunately, although neonatal jaundice is common, extreme hyperbilirubinemia is less common, and evaluation of this condition has frequently been inadequate.
JCAHO Recommendations in its 2001 Sentinal Event Alert
JCAHO is the Joint Commission on Accreditation of Healthcare Organizations and in April 2001 they issued a ‘Sentinel Event Alert’ on kernicterus. They compiled a root cause analysis and identified four failed patient care processes in the cases that resulted in the development of kernicterus. These included:
– Patient evaluation
– Continuous care
– Patient and family education
– Treatment
Regarding patient assessment, JCAHO noted lack of measurement of bilirubin levels in jaundiced infants within the first 24 hours, inability to recognize jaundice or its severity based on visual assessment, and unreliability of the visual evaluation of jaundice in newborns with dark skin. Continuity of care was inadequate in cases of discharge before 48 hours without follow-up within 1 to 2 days, particularly in infants less than 38 weeks’ gestation. Lack of early follow-up and physical evaluation of jaundiced infants prior to discharge and lack of ongoing breastfeeding support to maintain adequate intake in breastfed newborns were also identified as problems in continuity of care. . Patient and family education was considered inadequate in cases where adequate information was not provided to parents about jaundice and when physicians did not respond to parents’ concerns about a newborn with jaundice, problems with breastfeeding, or changes in the newborn’s activity and behavior. Treatment failures were due to failure to recognize, assess, and treat rapidly increasing total bilirubin levels and failure to aggressively and rapidly treat severe hyperbilirubinemia with intensive phototherapy or exchange transfusion.
Recommendations of the American Academy of Pediatrics
The Clinical Practice Guideline Management of hyperbilirubinemia in the newborn 35 weeks or more gestation was published in Pediatrics in 2004 and key recommendations included support for successful breastfeeding, establishment of protocols within the nursery for identification and evaluation of hyperbilirubinemia, measurement of total serum bilirubin or transcutaneous bilirubin levels in infants who present with jaundice within the first 24 hours of life, and recognition that visual evaluation is inadequate. Additionally, the Academy recommended that all bilirubin levels be interpreted using a nomogram that would allow an interpretation based on hours of life, that babies born less than 38 weeks gestation were at increased risk of developing severe hyperbilirubinemia, and that babies who were less than 38 weeks gestation had a higher risk of developing severe hyperbilirubinemia and breastfed had a higher risk. The Academy recommended that all infants be screened prior to discharge to determine the risk of severe hyperbilirubinemia and that parents receive written and verbal information about neonatal jaundice. Follow-up should be arranged at the time of discharge and risk assessment, and newborns should be treated immediately when the indications for treatment are evident, using phototherapy or exchange transfusion.
conclusion
Adherence to these clinical practice guidelines can prevent lifelong disability, and although kernicterus is relatively rare, newborn jaundice is common and should be thoroughly evaluated in light of risk factors and bilirubin measurement. serum total or transcutaneous bilirubin. Timely treatment is essential.
