ABSTRACT
Neural tube defects are an important group of congenital malformations that arise early in the gestation period as a result of abnormal embryological development of the neural tube. The embryological development of the neural tube and structure and function of the spinal cord are outlined in Chapter 1, Sections 2 and 8. Neural tube defects include a range of disorders such as anencephaly, encephalocele and spina bifida. Anencephaly occurs when the cephalic end of the neural tube fails to close. The result is an absence of the cranial vault and the presence of an occipital meningocele. Anencephaly is usually incompatible with life and often results in spontaneous abortion. In common with anencephaly, encephalocele occurs when the cephalic end of the neural tube fails to close but the presentation differs; there is a large fluid-filled sac that protrudes through the skull, usually in the region of the posterior fontanelle, and there may be associated structural malformations of the mid-brain. Prognosis is variable and influenced by the presence or absence of neuronal tissue within the sac and associated anomalies.
