Neural Tube Defects

Neural tube defects (NTDs) are a type of birth defect caused by the incomplete closure of the neural tube. They can range from almost no symptoms to severely disabling effects. This is an overview of the three main types of NTDs.

There are three types of NTDs: anencephaly, encephalocele, and spina bifida. Though none of the types may are fully preventable, the CDC recommends folic acid before and during pregnancy to reduce the risk of a fetus developing an NTD. The amount of folic acid recommended is 400 micrograms per day.³

Neural tube defects can manifest in several different forms, though they all occur when the baby's neural tube doesn't close properly during gestation. Some only mildly affect the child's quality of life, while others cause severely disabling problems.

Anencephaly

Anencephaly occurs when the neural tube closes incompletely and causes the brain and skull to be malformed. Often the child will be born without a forebrain, cerebrum, and parts of the skull and scalp. This causes the brain to be exposed during and after birth. Children born with this form of NTD almost always die before age two.¹

Encephalocele

Encephaloceles are a rare form of NTD. The CDC describes encephaloceles as: "a sac-like protrusion or projection of the brain and the membranes that cover it through an opening in the skull." This NTD causes an opening or hole in the midline of the skull in either the upper part of the skull, the area between the forehead and nose, or the rear side of the skull. Sometimes small encephaloceles go undetected; these ones are generally found in the nose or forehead area.²

Spina bifida

There are three common forms of spina bifida: myelomeningocele, meningocele, and spina bifida occulta.

Spina bifida occulta is a small gap in the spine. Generally the spinal cord and the nerves usually aren't damaged. This form usually doesn't cause any disabilities. People with this form often go undiagnosed because There aren't any physical problems associated with it. ³

A meningocele presents as a sac of fluid that protrudes from a hole in the baby's back, but the spinal cord does not enter the sac. This form has little to no nerve damage and few or minor disabilities. ³

According to the CDC, myelomeningocele is the most severe type of spina bifida. This form also involves the formation of a sac of fluid that comes through an opening on the baby's back. The spinal cord protrudes into the sac. The sac is also filled with spinal fluid. The spinal cord is damaged in this form as well. Myelomeningocele results in moderate to severe disabilities, which may include: problems going to the bathroom, loss of feeling in the legs or feet, and paralysis of the legs.³

Sources:
¹ Anencephaly , http://www.cdc.gov/ncbddd/birthdefects/Anencephaly.htm

² Encephalocele , http://www.cdc.gov/ncbddd/birthdefects/Encephalocele.htm

³ Spina Bifida , http://www.cdc.gov/ncbddd/spinabifida/facts.html