What is kernicterus?
Kernicterus is a preventable brain injury that involves permanent brain damage and other complications that may include cerebral palsy*, auditory neuropathy**, gaze abnormalities and dental enamel hypoplasia***. Kernicterus results from elevated levels of a naturally occurring neurotoxin, bilirubin. Early detection and treatment of hyperbilirubinemia is critical for prevention of kernicterus.
Newborn jaundice affects 60% of newborns in the United States each year and is the number one reason for hospital readmission during the first week of life. In the last two decades, changes such as relaxed jaundice management guidelines, shortened hospital stays and reduced concern about jaundice in general have led to an increase in cases of excessive jaundice and acute and chronic kernicterus. The long-term effects of excessive jaundice on the newborn brain can range from subtle (clumsiness, minor fine-motor deficits and sometimes mild auditory neuropathy) to severe (quadriplegia, total hearing loss, non-verbal). A few weeks after the severe jaundice incident, parents are typically able to identify abnormal newborn behaviors including poor feeding, irritability, sleep difficulty and muscle tone fluctuations. In addition, several secondary medical conditions are associated with kernicterus including severe reflux, sleep disturbances, respiratory infections and chronic constipation.
Kernicterus used to be common in the United States. In fact, in the 1950s, it was the second leading cause of cerebral palsy. By the 1970s, the medical community believed kernicterus had been eliminated, although it continued to occur outside the U.S., principally in underdeveloped countries. But times have changed. Babies are being discharged earlier and therefore may not be under the watchful eye of someone who knows what to look for and what to do. And parents, for the most part, aren’t warned about the risks associated with newborn jaundice. As a result, we are seeing a re-emergence of kernicterus.
* Athetoid Cerebral Palsy is a movement disorder caused by damage to a part of the brain responsible for processing signals that allow smooth coordinated movements and maintain body posture. In children with kernicterus, the damaged area is often the globus pallidus. Children with athetoid cerebral palsy typically have no cognitive impairment (normal intelligence), but may have difficulty maintaining posture and have involuntary movements that can interfere with walking, sitting, speaking, feeding, reaching and grasping.
** Auditory Neuropathy (AN) is a condition where the brain does not properly interpret the information being sent from the ear. In AN, the physiologic structure of the ear is normal (normal cochlear function) but the brainstem response to sound is abnormal. Patients with AN respond to sounds appropriately—they can hear—but their ability to decode speech and language is hindered. In children with kernicterus AN can be mild, leading to processing difficulties (i.e., difficult to discriminate sounds in noisy settings) to severe (complete inability to process sound leading to functional deafness)
*** Dental enamel hypoplasia is a defect of the teeth in which the tooth enamel is deficient, leading to soft teeth that are prone to cavities and can be stained green. In kernicterus, only the baby teeth are affected; adult teeth are typically normal.