Abnormal development of the central nervous system.

Abnormal development of the neural tube occurs with a high frequency and produces a wide range of malformations of the brain and spinal cord. Most dysraphic conditions are severe and, with the exception of meningomyelocele, lead to early death. This review deals with the more common clinically important neural malformations from the standpoint of epidemiology, etiology and pathogenesis based on both clinical and experimental observations.