ABSTRACT
Neural tube defects (NTDs) encompass a variety of congenital anomalies ranging from anencephaly to spina bifida occulta, and arise due to defects in the morphogenesis of the neural tube. There are geographic variations in the incidence of spina bifida and NTDs worldwide. NTDs result from an abnormality in the process of neurulation. The primitive streak and Hensen's nodes are present in the embryo at 2 weeks' gestation. All developmental defects of the central nervous system are NTDs. Types of NTDs vary in severity, ranging from anencephaly to spina bifida occulta. The term spina bifida occulta refers to spinal dysraphism not accompanied by extrusion of the contents of the vertebral column. A meningocele is an epithelium-lined sac filled with cerebrospinal fluid (CSF), which communicates with the spinal subarachnoid space. Myelomeningocele is the most common form of NTD. Substantial data have been accumulated to suggest that myelomeningocele and other neural defects can be reduced by improved maternal nutrition.
