Although most individuals with kernicteric cerebral palsy have normal intelligence, some children with mild choreoathetosis develop dull normal intelligence or mild intellectual disability even without auditory dysfunction. Causes
In the vast majority of cases, kernicterus is associated with unconjugated hyperbilirubinemia during the neonatal period. The blood–brain barrier is not fully functional in neonates and therefore bilirubin is able to cross into the central nervous system. Moreover, neonates have much higher levels of bilirubin in their blood due to:

Rapid breakdown of fetal red blood cells immediately prior to birth, with subsequent replacement by normal adult human red blood cells. This breakdown of fetal red blood cells releases large amounts of bilirubin. Severe hemolytic disease of the newborn. Many children who survive exhibit permanent mental impairment or damage to motor areas of the brain because of precipitation of bilirubin in neurons. Neonates have a limited ability to metabolize and excrete bilirubin. The sole pathway for bilirubin elimination is through the uridine diphosphate glucuronosyltransferase isoform 1A1 (UGT1A1) enzyme, which performs a reaction called "glucuronidation". This reaction adds a large sugar to the bilirubin, which makes the compound more water-soluble, so it can be more readily excreted via the urine and/or the feces. The UGT1A1 enzyme is not active in appreciable amounts until several months after birth. Apparently, this is a developmental compromise since the maternal liver and placenta perform glucuronidation for the fetus. Administration of aspirin to neonates and infants.
The thickness of the meniscus, its diminished vascular blood supply, and in some instances, weak capsular attachment, makes it more prone to tears compared to a normal meniscus. The anomaly in itself is asymptomatic; however, a tear of the meniscus can result in pain, swelling, and snapping in the affected knee. The orthopedic classification of discoid menisci includes: complete, incomplete or Wrisberg-ligament types as depicted here. Coverage of the lateral tibial plateau determines the designation of complete or incomplete. The Wrisberg-ligament type has an abnormal posterior attachment by attaching to part of the posterior cruciate ligament. Symptoms
Symptom is usually pain in the knee. And when the knee is bent or stretched it makes the sound of bouncing bones. Diagnosis
The transverse diameter of a normal meniscus is approximately 10 to 11 mm; therefore a normal meniscus body will be visible on only 2 slices of a MR with 4-5-mm sagittal slices. A discoid meniscus should be considered if more than two contiguous body segments are present. However, this method may lead to a false negative when evaluating people with the Wrisberg variant of discoid meniscus since it maintains a narrow crescent shape. Coronal and radial images of the meniscus are useful to demonstrate the extension of the aberrant meniscus into the joint as seen here. On coronal images, it is diagnosed when the horizontal measurement between the free margin and the periphery of the body is more than 1.4 cm.