Congenital and Developmental Diseases
Congenital or developmental disorders, which occur in a small percentage of
births, include a variety of structural and functional anomalies. A number of different abnormalities result from incomplete closure of the embryonic neural tube. Spina bifida, the commonest form, results from incomplete closure of the lumbar vertebral column. Syringomyelia is characterized by a
progressive formation of cavities extending from the central canal of the spinal cord, which results in the loss of perception of pain and temperature and later by weakness and wasting of muscles.
Cerebral palsy encompasses many different conditions that result from damage before birth, in the perinatal period or during the first few years of life. It may be caused by abnormal implantation of the ovum, maternal diseases, decreased blood supply or oxygen delivery to the fetus, intrauterine exposure to toxins, or trauma at the time of delivery, particularly trauma resulting in intracranial bleeding. Inherited defects of nervous system metabolism or storage, such as phenylketonuria or Tay-Sachs disease, cause specific enzyme deficiencies that result in abnormal accumulations of injurious chemical substances or lipids, and are usually progressive. A common feature of many of the inherited defects is mental
retardation. Chromosomal abnormalities such as Down syndrome are a frequent cause of mental retardation.