Structural Defects - Neural Tube Defects

Neural Tube Defects (NTD)

Neural tube defects arise when the neural tube does not close completely by the 29th day after conception.

Neural tube defects refer to structural defects of the nervous system during the developmental process. By about the first month of fetal life, the primitive structure that gives rise to the brain and spinal cord folds upon itself to give rise to a tube-like structure, the neural tube. The upper end forms the brain and the remaining forms the spinal cord. In some cases, this closure does not occur, and gives rise to neural tube defects.

The most common forms of NTDs are-

• Spina bifida
• Anencephaly

Spina bifida- When the closure defect is lower down in the neural tube, it gives rise to a condition commonly referred to as spina bifida. Spina bifida is of different types; the severity of the condition depends on the extent of the defect. Some patients with less severe types of spina bifida may live for many years with mild disabilities. The most severe form of spina bifida is characterized by paralysis or weakness below the level of the defect. Patients with such defects often have very poor control in terms of the bowel and bladder habits.

Anencephaly- When the closure failure occurs close to the upper end of the neural tube in the developing fetus, it gives rise to a condition called as ‘anencephaly’ meaning ‘no brain’. The brain and the associated structures lie exposed and highly disorganized. It usually results in a stillbirth, or death within the first few days of birth.