If the bilirubin is not rapidly reduced, ABE quickly progresses to chronic bilirubin encephalopathy. Chronic bilirubin encephalopathy (CBE)
CBE is a chronic state of severe bilirubin-induced neurological lesions. Reduction of bilirubin in this state will not reverse the sequelae. Clinically, manifestations of CBE include:
movement disorders – dyskinetic CP with often spasticity. 60% have severe motor disability (unable to walk). auditory dysfunction – auditory neuropathy (ANSD)
visual/oculomotor impairments (nystagmus, strabismus, impaired upward or downward gaze, and/or cortical visual impairment). In rare cases, decreased visual acuity(blindness) can occur. dental enamel hypoplasia/dysplasia of the deciduous teeth,
gastroesophageal reflux,
impaired digestive function. slightly decreased intellectual function: Although most individuals (approximately 85%) with kernicterus fall in normal or dull-normal range. epilepsy is uncommon.These impairments are associated with lesions in the basal ganglia, auditory nuclei of the brain stem, and oculomotor nuclei of the brain stem. Cortex and white matter are subtly involved. Cerebellum may be involved. Severe cortical involvement is uncommon. Subtle bilirubin encephalopathy (SBE)
SBE is a chronic state of mild bilirubin-induced neurological dysfunction (BIND). Clinically, this may result in neurological, learning and movement disorders, isolated hearing loss and auditory dysfunction. In the past it was thought that kernicterus (KI) often cause an intellectual disability. This was assumed due to difficulty with hearing, that is typically not detected in a normal audiogram accompanied by impairments of speech, with choreoathetosis. With advances in technology, this has proven to not be the case as those living with KI have repeatedly demonstrated their intelligence using Augmentative Communication devices.
Kernicterus is a bilirubin-induced brain dysfunction. The term was coined in 1904 by Christian Georg Schmorl. Bilirubin is a naturally occurring substance in the body of humans and many other animals, but it is neurotoxic when its concentration in the blood is too high, a condition known as hyperbilirubinemia. Hyperbilirubinemia may cause bilirubin to accumulate in the grey matter of the central nervous system, potentially causing irreversible neurological damage. Depending on the level of exposure, the effects range from clinically unnoticeable to severe brain damage and even death. When hyperbilirubinemia increases past a mild level, it leads to jaundice, raising the risk of progressing to kernicterus. When this happens in adults, it is usually because of liver problems. Newborns are especially vulnerable to hyperbilirubinemia-induced neurological damage, because in the earliest days of life, the still-developing liver is heavily exercised by the breakdown of fetal hemoglobin as it is replaced with adult hemoglobin and the blood–brain barrier is not as developed. Mildly elevated serum bilirubin levels are common in newborns, and neonatal jaundice is not unusual, but bilirubin levels must be carefully monitored in case they start to climb, in which case more aggressive therapy is needed, usually via light therapy but sometimes even via exchange transfusion. Classification
Acute bilirubin encephalopathy (ABE)
ABE is an acute state of elevated bilirubin in the central nervous system. Clinically, it encompasses a wide range of symptoms. These include lethargy, decreased feeding, hypotonia or hypertonia, a high-pitched cry, spasmodic torticollis, opisthotonus, setting sun sign, fever, seizures, and even death.