Backgrounder: Myelomeningocele

What is myelomeningocele?

Myelomeningocele (MY-ell-oh-men-NING-guh-seal) is the most severe form of spina bifida, a birth defect in which the spine does not fully close around the spinal cord. With myelomeningocele the spine protrudes through the opening of the spinal column and may be enclosed in a fluid-filled sac. Spina bifida belongs to a class of birth defects called neural tube defects, which affect the brain and spine. The exposed spinal cord is susceptible to injury, which may result in weakness and paralysis below the opening.

What are its effects?

The effects of myelomeningocele vary, depending on its location on the spine and the severity of the defect. Individuals with myelomeningocele may experience weakness and/or paralysis in the area below the defect, experience partial or complete loss of bladder and bowel control, have difficulty walking without assistance, or be unable to move the legs and feet. Individuals with myelomeningocele are also susceptible to hydrocephalus, a life-threatening buildup of fluid in the brain.

How is myelomeningocele treated?

Treatment involves surgery to close the opening on the baby’s spine. If there is a danger of hydrocephalus, a shunt, or tube, is inserted into the brain to drain the excess fluid into the abdominal cavity.

How widespread is the condition?

Myelomeningocele is estimated to occur at an average of 3.4 times for every 10,000 births.

Can women reduce their risk for conceiving a child who will develop a neural tube defect?

To reduce their risk of conceiving a child with myelomeningocele or another neural tube defect, the U. S. Public Health Service and CDC recommend that all women of childbearing age consume 0.4 mg (400 micrograms) of folic acid daily ( Folic acid, found in supplements or fortified foods, is the synthetic form of the vitamin folate. Women who have had a pregnancy affected by a neural tube defect are advised to take 4000 mcg (4 mg) of folic acid every day for one month before they start trying to get pregnant and every day for the first three months of the pregnancy.

In 2009, an NIH study found that women with low levels of vitamin B12, found in meat, eggs and other foods of animal origin, were at increased risk for having a child with a neural tube defect.

Information on sources of vitamin B12 and recommended daily allowances for the vitamin is available from the NIH Office of Dietary Supplements, at For other ways to reduce the risk of myelomeningocele and other types of spina bifida, visit, "Causes and Prevention."

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