Kernicterus on the Spectrum

Kernicterus is the potential toxic sequela of extreme neonatal hyperbilirubinemia resulting from the passage of excess free, unconjugated bilirubin across the blood−brain barrier, irreversibly and selectively damaging vulnerable target brain cells including the basal ganglia, the cerebellum, and the auditory system. Kernicterus continues to plague the modern world. Not only does it continue to be uncontrolled in developing countries with underdeveloped medical systems, and health organizations rendered ineffective by the ravages of war, but it also remains prevalent in industrialized countries. In this review, we attempt to clarify the different and overlapping nomenclature used in the past to describe this entity and aim to offer a uniform approach to defining kernicterus spectrum disorder. We also discuss the different spectrum subtypes including motor-predominant kernicterus, auditory neural sensory dysfunction, subtle kernicterus, and kernicterus plus. In addition to reviewing several genetic factors that increase the risk of developing kernicterus, we also present some exciting potential therapeutic approaches.