Kernicterus is a serious condition and a cause of brain damage and hearing loss in newborn babies. High levels of bilirubin cause it. Kernicterus refers to the yellow colour of the brain nuclei stained by the bilirubin as seen at autopsy.
Most children with kernicterus are fully cognitive, aware and able to learn and interact. This fact is usually mistakenly overshadowed by their hearing loss, speech impairment, cerebellar palsy and gaze palsy.
It occurs in the first week of life, but may be seen in the second or third week. It is more common in boys and in premature babies. Other risk factors include large for gestational age, glucose 6 phosphodehydrase deficiency, Rhesus (RH) incompatibility and breast milk feeding.
Bilirubin is a normal by-product of red blood cell break down and is excreted by the liver. An increase in bilirubin levels (hyperbilirubinemia) leads to jaundice in patients. In newborn babies the blood brain barrier is not fully developed so that the excess bilirubin can easily enter the brain. Bilirubin is highly toxic to brain cells (grey matter). It is specifically seen where there are high densities of neurons such as the basal ganglia. The cochlear nucleus and auditory nerves are specifically affected. Patients may then suffer from hearing loss of various degrees.
Kernicterus associated hearing loss includes:
Sensorineural hearing loss impairs a child’s ability to hear sounds voices and follow conversations. Sound and speech are perceived as soft or muffled. This will inevitably lead to impaired speech and language development.
In auditory neuropathy the nerve malfunctions and signals from the ear to the brain are not transmitted properly. Patients complain of sounds fading in and out and being out of sync. The main problem with auditory neuropathy is the understanding of speech and difficulty distinguishing sounds.
Hearing aids and cochlear implantation can improve hearing. Cochlear implants can benefit deaf children with auditory neuropathy due to kernicterus. To improve communication, intensive therapy in listening skills is required. Some patient may benefit from sign language.
Patients should be managed in a team.
- Hyperbilirubinemia and Kernicterus, Shapiro Steven et al, Clin Perinatol 33 (2006) 387-410