Medical Info: Kernicterus

Kernicterus is a rare neurological disorder characterized by excessive levels of bilirubin in the blood (hyperbilirubinemia) during infancy. Bilirubin is an orange-yellow bile pigment that is a byproduct of the natural breakdown of hemoglobin in red blood cells (hemolysis). Toxic levels of bilirubin may accumulate in the brain, potentially resulting in a variety of symptoms and physical findings.

These symptoms may include lack of energy (lethargy), poor feeding habits, fever, and vomiting. Affected infants may also experience the absence of certain reflexes (e.g., Moro reflex, etc.); mild to severe muscle spasms including those in which the head and heels are bent backward and the body bows forward (opisthotonus); and/or uncontrolled involuntary muscle movements (spasticity). In some cases, infants with kernicterus may develop life-threatening complications.

Medical info:

Pathophysiology:
Bilirubin staining can be noted on autopsy of fresh specimens in the regions of the basal ganglia, hippocampus, substantia nigra, and brainstem nuclei. Such staining can occur in the absence of severe hyperbilirubinemia; in this situation, factors influencing permeability of the blood-brain barrier (eg, acidosis, infection) and the amount of unbound (versus albumin-bound) bilirubin may play a role.

Characteristic patterns of neuronal necrosis leading to the clinical findings consistent with chronic bilirubin encephalopathy are also essential in the pathophysiology of this entity. Bilirubin staining of the brain without accompanying neuronal necrosis can be observed in babies who did not demonstrate clinical signs of bilirubin encephalopathy but who succumbed from other causes. This staining is thought to be a secondary phenomenon, dissimilar from the staining associated with kernicterus.