Prenatal Origin of Hemiparetic Cerebral Palsy: How Often and Why?

"Consider what must be accomplished during the course of fetal brain development. In effect, in a few months the entire work of hundreds of millions of years of evolution must be reachieved. . . . Tens of billions of neurons must be born. . . . These new cells must find their way to their anatomical destinations, sometimes moving over substantial distances in an embryo that is constantly changing in form. . . Once the cell is fixed in place, the axon must find its way to its own destination. . . . They must not only get where they are going and make a connection, but they must avoid making any number of other connections that they might wrongly make in places they pass. Each nerve cell must develop one or more of at least a dozen neurotransmitters. . . ." The product of that miracle is the most complicated object in the known universe, a human brain. In this "Decade of the Brain," we can anticipate the emergence of a great deal more information about how the nervous system develops, prenatally and thereafter, and how and when that development can go awry. That information will come from laboratories, clinics, and nurseries. Neuroimaging of the infant brain, a subject now producing a rich harvest in journals of pediatrics, neurology, radiology, and obstetrics, will contribute important new information about the processes of brain development in our species, the timing of derailment from the normal course of brain development, and some aspects of pathogenesis. Neuropathology and the enormous flowering of new approaches in the basic and clinical neurosciences will help in explication of the mechanisms of maldevelopment and early injury. And we can hope that identification of mechanisms will allow us to develop strategies to prevent at least some of the problems leading to prenatal damage of the developing human brain.