Spina Bifida

Spina bifida, also known as myelomeningocele, is a birth defect that occurs when an area of an unborn baby’s spine does not form properly in the womb, exposing a section of the spinal cord and spinal nerves. This results in damage to the baby’s nervous system. It is the most common neural tube defect in the United States, affecting approximately 2,000 babies born in the country each year.

Traditionally, infants with spina bifida have surgery shortly after birth to repair the spinal defect. Today, repairing the spina bifida before birth, otherwise known as maternal-fetal surgery or in utero repair, is considered an effective treatment option to potentially reduce the risk of complications and improve the outcome in babies affected with spina bifida.

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Women with pregnancies complicated by fetal myelomeningocele who meet established criteria for in utero repair should be counseled in a nondirective fashion regarding all management options, including the possibility of open maternal–fetal surgery. Maternal–fetal surgery for myelomeningocele repair should be offered only to carefully selected patients at facilities with an appropriate level of personnel and resources.

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Spina bifida (myelomeningocele) is characterized by the abnormal development of the fetal spinal cord and/or meninges, the protective covering around the brain and spinal cord, during early pregnancy. When the neural tube, which forms the brain and spinal cord, does not close completely during fetal development, the malformed vertebrae (bones) in the backbone remain open allowing exposure of the spinal cord and spinal nerves, resulting in damage to the baby’s nervous system.

This neural tube defect can occur anywhere along the spinal column, and the severity of the neurological problems is often dependent on the location of the defect. Children with defects of the lower spine typically have better outcomes than those who have defects of the upper spine. The symptoms of spina bifida might cause disabilities that range from mild conditions such as difficulty walking to complete paralysis and impaired bladder and bowel function.

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There are several types or variations of spina bifida. These variations depend on how the neural tube defect develops, what is protruding through the open neural tube, and what is covering the spina bifida abnormality. These variations include:

Myelomeningocele (MMC) is the most common and most severe form of spina bifida. With myelomeningocele, a sac of fluid that holds part of the spinal cord and nerve tissue protrudes through an opening in the baby’s back. This damages the spinal cord and nerves through exposing them to the amniotic fluid. MMC can result in partial or complete paralysis of the body below the level of the spinal opening, an inability to walk, and/or bladder and bowel dysfunction.

Myeloschisis is a flat neural tube defect without a layer of skin covering the opening in the spine. With myeloschisis, the spinal cord and the surrounding nerve tissue are also exposed to the amniotic fluid. This form of spina bifida has similar risks and symptoms as myelomeningocele.

MMC and myeloschisis are both open neural tube defects, which are treatable by fetal repair surgery.

Meningocele is a form of spina bifida where there is an outpouching or sac through an abnormal opening in the fetal spine, but the sac contains only spinal fluid. This abnormality does not contain any nerve tissues. Often the sac is covered by skin. Babies with meningocele may have few or no symptoms, while others may develop degrees of paralysis with bladder and bowel dysfunction.

Spina bifida occulta, or “hidden spina bifida,” is the mildest form of spina bifida, where a small gap in the spine occurs, but there is no opening or sac on the baby’s back. Often not discovered until late childhood or early adulthood, this condition usually does not cause any disabilities as the spinal cord and the nerves are typically normal.

In most cases, the causes of spina bifida are unknown, though it has been associated with maternal diabetes, certain medications and certain genetic problems. The Center for Disease Control and Prevention urges all women capable of becoming pregnant to take 400 micrograms or more of folic acid every day for at least three months prior to pregnancy to help prevent neural tube defects.

While the symptoms of spina bifida can range from mild to severe, most children with spina bifida experience major disabilities throughout their lifetime. These include: neuromuscular issues; paralysis of the lower limbs, or the inability to walk; bowel and bladder control difficulties; brain abnormalities such as brain herniation; and learning disabilities.

Spina bifida can be diagnosed during pregnancy. A common blood test, maternal serum alpha-fetoprotein (AFP), is offered during the 15th to 20th week of pregnancy to screen for spina bifida. If the levels of alpha-fetoprotein are abnormal (elevated), doctors can use additional tests, such as ultrasound and amniocentesis, to diagnose spina bifida. Use of the AFP test along with an ultrasound typically identifies 90% of cases.

If it is determined that the unborn baby has spina bifida, both mom and baby should be referred to a high-risk pregnancy specialist for further evaluation. A series of ultrasounds will be performed throughout pregnancy to monitor the baby’s progress. A chromosomal analysis may be recommended to identify chromosomal abnormalities. Other tests, including a fetal MRI or fetal echocardiogram, may be recommended if other abnormalities are suspected. A pediatric neurosurgeon will evaluate the prenatal tests and discuss neonatal care and long-term outcome.

When you contact The Fetal Center, you will be in touch with a dedicated coordinator who will walk you through the process step-by-step and help you to understand every aspect of your care.

The Fetal Center at Children's Memorial Hermann Hospital
UT Professional Building
6410 Fannin, Suite 210
Houston, Texas 77030

Phone: (832) 325-7288
Toll free: (888) 818-4818
Fax: (713) 383-1464
Email: thefetalcenter@memorialhermann.org

Located within the Texas Medical Center, The Fetal Center is affiliated with McGovern Medical School at UTHealth Houston, UT Physicians and Children’s Memorial Hermann Hospital.