Definition of Neural Tube Defects
Neural Tube Defects – birth defects in which the neural tube, the precursor to the spinal cord and brain, fails to develop properly. The neural tube develops in the first few weeks of gestational life and may be complete by the time a woman knows she is pregnant. An open neural tube defect exposes the brain and spinal cord outside the body.
Skin and spinal structure abnormally encase a closed neural tube defect, typically involving only the spine (and usually the lower spine). Though there are associations between neural tube defects and chromosomal disorders such as Down syndrome, most researchers believe neural tube defects occur as a combination of random gene mutation and environmental circumstances.
The most serious neural tube defect is anencephaly, in which the brain does not form. Anencephaly is always fatal. Spina bifida, in which the spinal column does not close properly, can result in mild to debilitating deformity and disability. The mildest form of spina bifida is myelomeningocele, in which the defect affects only a small portion of the lower spinal cord. Reconstructive surgery can improve protection of the spinal cord, though a degree of paralysis affecting bowel, bladder, and lower body function typically remains. Occasionally a neural tube defect is so minor that it does not become apparent until later in life, even adulthood.
Folic acid supplementation, ideally beginning before conception, can prevent most neural tube defects. Health experts recommend all sexually active women of childbearing age take folic acid supplements whether or not they plan pregnancy. (Folic acid supplementation also helps stabilize blood glucose levels in pregnant women who have diabetes.) Alpha fetoprotein (afp), chorionic villi sampling (cvs), and prenatal ultrasound can detect most neural tube defects before birth, allowing women and their doctors to make decisions about the course of the pregnancy and care needs following birth. Doctors often recommend terminating the pregnancy when the neural tube defect is so severe that death of the infant would be certain and immediate after birth.
See also ABORTION; CONGENITAL ANOMALY; KYPHOSIS; SCOLIOSIS.
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