Degenerative disorders of the central nervous system.

A child's development generally proceeds along expected pathways, with anticipated levels of function for specific ages. When these levels are not met, the treating physician must determine whether the child has a static or a progressive process. If the child achieves certain levels of development, then loses these skills, the chance is greater that the process is progressive. The technological revolution and progress in molecular genetics in the past 20 to 30 years provide greater avenues for the diagnosis of many of the progressive disorders affecting neurons and central nervous system (CNS) function. Many disorders can be diagnosed in utero, and treatments are available for some. It has become increasingly evident that many of the inherited neurodegenerative disorders have varied clinical phenotypes, and clinical phenotypes may overlap between some of the disorders. This article provides a framework for the primary physician to consider some of these disorders and a rational approach to the evaluation of a child suspected of having a progressive neurodegenerative disorder.