Spina Bifida

Brief Information

Introduction

Spina bifida is caused by problems in the development of an embryo in the womb. It is known as a neural tube defect as it results from the failure of the embryos neural tube to develop properly.

The neural tube forms in the first few weeks of pregnancy and eventually goes on to form the baby's brain, spinal chord and their coverings. Spina bifida is when neural tube does not develop properly and this results in an incorrectly developed spine.

The features of spina bifida vary between individuals, but commonly the small bones that make up the spine (the vertebrae) have not formed fully and may have gaps in them.  In severe cases, one or more vertebrae may be missing, exposing the spinal chord (part of the nervous system that transmits signals from the nerve endings to the brain).

Normally, the neural tube is fully closed between 26 and 28 days after the start of the pregnancy. Very rarely, the neural tube fails to close or tears after it has closed.

This can affect the foetus in several different ways. In the least serious form, known as spina bifida occulta, the condition is hidden and usually is discovered only on X ray or through scanning. This type actually affects up to 30% of the population, nearly all of whom never become aware of it.

In the next most serious type, the coverings of the cord (the meninges) pass back through the opening to form a cyst-like swelling called a meningocele.

In the most serious type, the spinal cord itself is exposed. This is called a myelomeningocele or spina bifida aperta.

Myelomeningocele is more common in females than in males. The condition affects white people more often than black and Asian people, and tends to run in families. If the first child has myelomeningocele, the risk for the second child rises to 5%. If two children have myelomeningocele, the risk for a third is 15%.

Taking folic acid supplements reduces the risk of spina bifida. The Department of Health recommends that women should take a daily supplement of 0.4mg of folic acid while they are trying to become pregnant, and for the first twelve weeks of pregnancy. Folic acid tablets can be obtained from pharmacies, large supermarkets, health food stores and by prescription.

Causes

The condition occurs early in pregnancy, when the baby's spine is being formed. It happens because the neural tube fails to fuse and close fully. Why this happens is unknown, but lack of folate (folic acid) early in pregnancy contributes to it.

Treatment

Surgery to correct the defect is usually performed as soon as possible after birth. 

More Information

• Association for spina bifida and hydrocephalus

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