Spina bifida

Spina bifida is a birth disorder that involves the incomplete development of the spine. In the first month of pregnancy, a special set of cells forms the “neural tube;” the top of the tube becomes the brain, and the remainder becomes the spinal cord and structures around it. In spina bifida, the neural tube doesn’t close completely and some of the bones of the spine do not close in the back. This can result in an opening anywhere along the spine and may cause damage to the spinal cord and nerves.

The term "neural tube defect" describes a group of conditions, including spina bifida, that usually occur very early in pregnancy when the neural tube does not form as expected.

Often, abnormalities of the brain accompany abnormalities of the spine because the neural tube closes first in the middle and then closure proceeds both upward and downward, meaning that if something happens that prevents formation of the spine, it may also prevent formation of the part of the brain that is forming (closing) at the same time.

An infant born with spinal bifida may have nerve damage below the affected area of the spinal cord. Some will have learning disabilities or intellectual disabilities. There is no cure but most people with spina bifida lead long lives. People with spina bifida have different abilities and medical issues.

Types of spina bifida. There are four types of spina bifida: occulta, closed neural tube defects, meningocele, and myelomeningocele. The symptoms of spina bifida vary from person to person, depending on the type and level of involvement. Most cases are mild and do not require special treatment. The more serious cases involve nerve damage.

1. Occulta is the mildest and most common form in which one or more bones of the spinal column (vertebrae) are malformed. The name “occulta,” which means “hidden,” indicates that a layer of skin covers the opening in the bones of the spine. It usually shows no symptoms and is often found by accident on an x-ray or similar test.
2. Closed neural tube defects are a diverse group of disorders in which the spine may have malformations of fat, bone, or the membranes (the meninges) that cover the spinal cord. Many of these neural tube defects require surgery in childhood. People with this type of spina bifida may have weakness of the legs and trouble with bowel and bladder control. These issues may change or progress as children grow. It is important to have close communication with doctors to minimize these changes as much as possible.
3. Meningocele occurs when the meninges protrude through the spine and cause a sac of spinal fluid on the back. This fluid is typically only around the brain and spine, but a problem with the bony covering over the spine allows it to poke out. The malformation contains no nerves and may or may not be covered by a layer of skin. Individuals with meningocele may have minor symptoms.
4. Myelomeningocele is the most severe form of spina bifida. A portion of the spinal cord or nerves are exposed in a sac through an opening in the spine that may or may not be covered by the meninges. The opening can be closed surgically while the baby is in utero or shortly after the baby is born. Most people with myelomeningocele experience changes in brain structure, leg weakness, and bladder and bowel dysfunction.
   • Myelomeningocele is often called a "snowflake condition" because no two people with the condition are the same. Typically, if the opening in the spine is lower down the back, the person will experience less symptoms. People with myelomeningocele require close follow-up with physicians throughout their childhood and lifespan to maximize their function and prevent complications like kidney failure.

Complications of spina bifida may include:

• Abnormal sensation or paralysis, which mostly occurs with closed neural tube defects and myelomeningocele. There is usually some degree of leg and core muscle weakness and loss of feeling in the groin and feet or legs. The sensation can be more significant on one side of the body. Typically, there is less weakness and loss of the feeling when the condition occurs lower in the spine. The strength and feeling do not improve with age due to nerve damage. People with these types of spina bifida may lose strength, sensation, and mobility as they age. They may walk independently or use some combination of leg braces, walkers, crutches, or wheelchairs.
• Chiari II malformation, in which the brain stem and the cerebellum protrude downward into the spinal canal or neck area, is almost always seen on advanced imaging of the brain in people with myelomeningocele yet it rarely causes symptoms. When it does, this condition can press on the spinal cord and cause a variety of symptoms including:
  • Difficulty breathing
  • Swallowing
  • Arm weakness
• Blockage of cerebrospinal fluid causes hydrocephalus, or the abnormal buildup of the fluid that surrounds the brain. Most people with myelomeningocele have this condition, altougth it is not seen in other types of spina bifida. This buildup can put damaging pressure on the brain. Hydrocephalus is commonly treated by surgically implanting a plastic shunt (hollow tube) in the brain to drain the excess fluid into the abdomen where it is absorbed by the body. Another treatment option is an endoscopic third ventriculostomy (ETV), a procedure that creates a new path for the fluid to flow.
  • Meningitis, an infection in the meninges covering the brain, can sometimes be associated with shunts. Meningitis may cause brain injury and can be life-threatening.
• Tethered cord syndrome can occur with all forms of spina bifida, although it is very rare in individuals with spina bifida occulta. Usually the spinal cord and nerves float freely. A tethered cord means that there is some type of tissue attached to and pulling the cord down (e.g., the cord may become fastened to the backbone). This can damage the nerves, decrease feeling and strength, and cause problems with bowel and bladder control. Surgery to free the cord is often successful.
• Incontinence affects most individuals with myelomeningocele and closed neural tube defects because the nerves that control bowel and bladder function at the very bottom of the spine are involved. Most people with myelomeningocele and some types of closed neural tube defects need a regimen or other assistance with bladder and bowel function.
• Learning disabilities commonly seen in children with myelomeningocele may include:
  • Difficulty paying attention and understanding concepts
  • Impaired motor skills and memory
  • Challenges with organization and problem solving

Other complications seen in people with myelomeningocele and neural tube defects as they age may include:

• Skin ulcers
• Low bone mineral density
• Impaired male fertility
• Obesity kidney failure
• Precocious puberty (when changes are premature/occur too soon)
• Sleep apnea
• Depression

Who is more likely to get spina bifida?

Each year approximately 1,400 babies born in the U.S. have spina bifida, according to the U.S. Centers for Disease Control and Prevention (CDC). The exact cause of spina bifida is unknown but scientists suspect genetic, nutritional, and environmental factors all play a role in its development.

How is spina bifida diagnosed and treated?

Diagnosing spina bifida. In most cases, spina bifida is diagnosed before birth (prenatal). However, some mild cases may go unnoticed until after birth (postnatal). Very mild forms of spinal bifida are found when doing tests for other conditions or may never be detected.

Prenatal Diagnosis

The most common screening methods to look for spina bifida during pregnancy are maternal serum alpha fetoprotein (MSAFP) screening and fetal ultrasound. A doctor can also perform an amniocentesis test.

• Maternal serum alpha fetoprotein (MSAFP) screen—At 16 to 18 weeks of pregnancy (second trimester), a sample of the mother's blood is taken to measure the level of a protein called alpha-fetoprotein (AFP), which is made naturally by the fetus and placenta. Signs of spina bifida are not evident until the second trimester. During pregnancy, a small amount of AFP normally crosses the placenta and enters the mother's bloodstream. Abnormally high levels of AFP may indicate—but not necessarily confirm—the fetus has spina bifida or other neural tube defect. If a high level of AFP is detected, the doctor may request additional testing, such as an ultrasound or amniocentesis.
  • This test is not specific for spina bifida. The MSAFP screen may be performed alone or as part of a larger, multiple-marker screen that looks for neural tube defects and other birth defects, including Down syndrome and other chromosomal abnormalities.
• Ultrasound—High-frequency sound waves create a picture of the developing baby inside the womb. It is highly accurate in diagnosing some birth defects during pregnancy, including spina bifida. Fetal ultrasound can be performed during the first trimester (usually between 11 to 14 weeks) and the second trimester (usually at 18 to 22 weeks), but diagnosis is more accurate during the second trimester.
• Amniocentesis—A sample of the amniotic fluid that surrounds the fetus is removed and tested for protein levels that may indicate a neural tube defect or genetic disorder.

Postnatal Diagnosis

Closed neural tube defects are often spotted at birth due to an abnormal fatty mass, tuft or clump of hair, or a small dimple or birthmark on the skin at the site of the spinal malformation. Spina bifida occulta is usually found when x-rays are done for another reason.

In rare cases, myelomeningocele and meningocele are not diagnosed during routine prenatal tests. The baby will be diagnosed when it is born with a bubble on its back. Babies with myelomeningocele and closed neural tube defects may have muscle weakness in their feet, hips, and legs that result in joint deformities first noticed at birth. Mild cases of spina bifida (occulta and closed neural tube defects) that are not diagnosed during prenatal testing may be detected postnatally using ultrasound or X-ray imaging to look at the spine.

Doctors may use magnetic resonance imaging (MRI) or a computed tomography (CT) scan to get a clearer view of the spinal cord and vertebrae. To evaluate for hydrocephalus, the doctor will request a head ultrasound, CT, or MRI to look for extra cerebrospinal fluid inside the brain.

Treating Spina Bifida. Treatment depends on the type of spina bifida. Myelomeningocele and meningocele require surgery to close the bubble shortly after birth to prevent infection such as meningitis. Most people with myelomeningocele have hydrocephalus and most of them will need a shunt placed as an infant. Children with a closed neural tube defect may need surgery to prevent further complications such as weakness and bowel and bladder function. Generally, people with spina bifida occulta will not need any treatment.

Prenatal Surgery

Prenatal surgery involves opening the mother's abdomen and uterus (or womb) and sewing the abnormal opening over the developing baby's spinal cord so that it is closed. This can protect the baby's spinal cord from ongoing damage in the uterus.

The Management of Myelomeningocele Study (MOMS) showed that prenatal surgery to close the defect in the spinal cord improved outcomes compared to children who had postnatal surgery for spina bifida. Prenatal surgery reduced the need to drain fluid from the brain, improved mobility, and increased the chances that a child will be able to walk independently early on. This study was funded by the National Institutes of Health (NIH) Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).

Surgery does not restore lost neurological function but may prevent additional damage during the rest of the pregnancy. Prenatal surgery poses some risk to the fetus as well as to the mother.

Postnatal Surgery

In treating myelomeningocele and meningocele, a child who has not had prenatal surgery will have surgery within the first few days of life to close the defect and minimize the risk of infection or further trauma to the exposed nerves and spinal cord.

Tethered cord syndrome can be treated with surgery to help prevent further neurological deterioration.

Treatments for Complications

Some children with myelomeningocele and closed neural tube defects will need surgery to improve the alignment of their feet, legs, or spine. Children with myelomeningocele usually have hydrocephalus and may require surgery to help drain fluid in the brain, such as the placement of a shunt or ETV. Multiple surgeries may be required to replace the shunt, which may become clogged, infected, or disconnected.

Some individuals with myelomeningocele or closed neural tube defects require assistive devices for mobility such as:

• Braces
• Walkers

• Crutches
• Wheelchairs

Children with myelomeningocele usually have some degree of delayed mobility, so they are referred to physical therapists early on to maximize their strength and function.

Treatment for bladder and bowel dysfunction typically begins soon after birth. Children with myelomeningocele and some closed neural tube defects have damage to the lowest spinal nerves which control typical bowel and bladder function. Kidneys are monitored closely so that medications or surgeries can be performed to prevent renal failure. Close follow-up with a spina bifida specialty clinic is recommended to develop a safe bowel and bladder program.

Folic Acid—Folic acid (folate) is an important vitamin for the development of a healthy fetus. Although taking this vitamin cannot guarantee having a healthy baby, it can help. Studies show that women of childbearing age who add folic acid to their diets can significantly reduce the risk of having a child with a neural tube defect. Doctors recommended that all women of childbearing age take a daily vitamin supplement with 400 micrograms of folic acid before and during early pregnancy.

Females who already have a child with spina bifida, who have spina bifida themselves, or who have already had a pregnancy affected by any neural tube defect are at greater risk of having another child with a neural tube defect. They should take a higher prescription dose of folic acid before and early in pregnancy.

Foods that are high in folic acid include:

• Dark green, leafy vegetables
• Egg yolks
• Some fruits (banana, citrus, papaya)

Many foods—such as some breakfast cereals, enriched breads, flours, pastas, rice, and other grain products—are now fortified with folic acid. Many multivitamins contain the recommended dosage of folic acid as well.

What are the latest updates on spina bifida?

The National Institute of Neurological Disorders and Stroke (NINDS), one of the National Institutes of Health (NIH), is a primary federal supporter of research on brain and nervous system disorders. In addition to NINDS, other NIH Institutes support research on spina bifida and neural tube defects.

Genetic studies. In one study supported by NINDS, scientists are looking at the hereditary basis of neural tube defects and hope to find the genetic factors that make some children more likely to have a neural tube defect. These researchers are also studying gene expression during the process of normal neural tube closure, which will provide information on the human nervous system during development.

In addition, NINDS-supported scientists are working to identify, characterize, and evaluate genes involved in neural tube defects. The goal is to understand the genetics of neural tube closure and to develop information that will lead to improved clinical care, treatment, and genetic counseling.

Other scientists are studying genetic risk factors for spina bifida, especially those that reduce the effectiveness of folic acid in preventing spina bifida. This study will shed light on how folic acid prevents spina bifida and may lead to improved forms of folate supplements.

Developmental studies. NINDS supports and conducts a wide range of basic research studies to understand how the brain and nervous system develop. These studies contribute to a greater understanding of neural tube defects such as spina bifida and offer hope for new ways to treat and potentially prevent these disorders as well as other birth defects.

Surgery. Results of the Management of Myelomeningocele Study (MOMS) showed significant benefit to the developing baby. Because fetal surgery has shown promise, NINDS-funded researchers are also developing new methods, such as stem cell patches and tissue engineering, to add to the prenatal repair of spinal defects.

More research efforts. More information about research on spina bifida can be found using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies. RePORTER also includes links to publications and resources from these projects.

How can I or my loved one help improve care for people with spina bifida?

Consider participating in a clinical trial so clinicians and scientists can learn more about spina bifida. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with spina bifida at Clinicaltrials.gov, a database of current and past clinical studies.

Where can I find more information about spina bifida?

Information may be available from the following organizations:

Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
Phone: 800-370-2943 or 888-320-6942

March of Dimes
Phone: 914-997-4488 or 888-663-4637

MedlinePlus

PubMed

Spina Bifida Association
Phone: 202-944-3285 or 800-621-3141

Content source: https://www.ninds.nih.gov/health-information/disorders/spina-bifida Accessed July 17, 2023.

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