Spina bifida

Spina Bifida

The human nervous system develops from a small, specialized plate of cells along the back of an embryo (called the neural plate). Early in development, the edges of this plate begin to curl up toward each other, creating the neural tube—a narrow sheath that closes to form the brain and spinal cord of the embryo. As development progresses, the top of the tube becomes the brain and the remainder becomes the spinal cord. This process is usually complete by the 28^th day of pregnancy. But if problems occur during this process, the result can be brain disorders called neural tube defects, including spina bifida.

Spina bifida

What is spina bifida?

Spina bifida, which literally means “cleft spine,” is characterized by the incomplete development of the brain, spinal cord, and/or meninges (the protective covering around the brain and spinal cord). It is the most common neural tube defect in the United States—affecting 1,500 to 2,000 of the more than 4 million babies born in the country each year. An estimated 166,000 individuals with spina bifida live in the United States.

What are the different types of spina bifida?

There are four types of spina bifida: occulta, closed neural tube defects, meningocele, and myelomeningocele.

Occulta is the mildest and most common form in which one or more vertebrae are malformed. The name “occulta,” which means “hidden,” indicates that a layer of skin covers the malformation, or opening in the vertebrae. This form of spina bifida, present in 10-20 percent of the general population, rarely causes disability or symptoms.

Closed neural tube defects make up the second type of spina bifida. This form consists of a diverse group of defects in which the spinal cord is marked by malformations of fat, bone, or meninges. In most instances there are few or no symptoms; in others the malformation causes incomplete paralysis with urinary and bowel dysfunction.

Spina bifida with anencephaly

In the third type, meningocele, spinal fluid and meninges protrude through an abnormal vertebral opening; the malformation contains no neural elements and may or may not be covered by a layer of skin. Some individuals with meningocele may have few or no symptoms while others may experience such symptoms as complete paralysis with bladder and bowel dysfunction.

Myelomeningocele, the fourth form, is the most severe and occurs when the spinal cord/neural elements are exposed through the opening in the spine, resulting in partial or complete paralysis of the parts of the body below the spinal opening. The impairment may be so severe that the affected individual is unable to walk and may have bladder and bowel dysfunction.

What causes spina bifida?

The exact cause of spina bifida remains a mystery. No one knows what disrupts complete closure of the neural tube, causing this malformation to develop. Scientists suspect the factors that cause spina bifida are multiple: genetic, nutritional, and environmental factors all play a role. Research studies indicate that insufficient intake of folic acid—a common B vitamin—in the mother’s diet is a key factor in causing spina bifida and other neural tube defects. Prenatal vitamins typically contain folic acid as well as other vitamins. (See “Can the disorder be prevented?” for more information on folic acid.)

Spina bifida

What are the signs and symptoms of spina bifida?

The symptoms of spina bifida vary from person to person, depending on the type and level of involvement. Closed neural tube defects are often recognized early in life due to an abnormal tuft or clump of hair or a small dimple or birthmark on the skin at the site of the spinal malformation.

Meningocele and myelomeningocele generally involve a fluid-filled sac—visible on the back—protruding from the spinal canal. In meningocele, the sac may be covered by a thin layer of skin. In most cases of myelomeningocele, there is no layer of skin covering the sac and an area of abnormally developed spinal cord tissue is usually exposed.

What are the complications of spina bifida?

Complications of spina bifida can range from minor physical problems with little functional impairment to severe physical and mental disabilities. It is important to note, however, that most people with spina bifida are of normal intelligence. Spina bifida’s impact is determined by the size and location of the malformation, whether it is covered, and which spinal nerves are involved. All nerves located below the malformation are affected to some degree. Therefore, the higher the malformation occurs on the back, the greater the amount of nerve damage and loss of muscle function and sensation.

In addition to abnormal sensation and paralysis, another neurological complication associated with spina bifida is Chiari II malformation—a condition common in children with myelomeningocele—in which the brain stem and the cerebellum (hindbrain) protrude downward into the spinal canal or neck area. This condition can lead to compression of the spinal cord and cause a variety of symptoms including difficulties with feeding, swallowing, and breathing control; choking; and changes in upper arm function (stiffness, weakness).

Sagittal MRI scan of brain of patient with Chiari malformation

Chiari II malformation may also result in a blockage of cerebrospinal fluid, causing a condition called hydrocephalus, which is an abnormal buildup of cerebrospinal fluid in and around the brain. Cerebrospinal fluid is a clear liquid that surrounds the brain and spinal cord. The buildup of fluid puts damaging pressure on these structures. Hydrocephalus is commonly treated by surgically implanting a shunt—a hollow tube—in the brain to drain the excess fluid into the abdomen.

Some newborns with myelomeningocele may develop meningitis, an infection in the meninges. Meningitis may cause brain injury and can be life-threatening.

Children with both myelomeningocele and hydrocephalus may have learning disabilities, including difficulty paying attention, problems with language and reading comprehension, and trouble learning math.

Additional problems such as latex allergies, skin problems, gastrointestinal conditions, and depression may occur as children with spina bifida get older.

How is it diagnosed?

In most cases, spina bifida is diagnosed prenatally, or before birth. However, some mild cases may go unnoticed until after birth (postnatal). Very mild forms (spinal bifida occulta), in which there are no symptoms, may never be detected.

Prenatal Diagnosis

The most common screening methods used to look for spina bifida during pregnancy are second trimester (16-18 weeks of gestation) maternal serum alpha fetoprotein (MSAFP) screening and fetal ultrasound. The MSAFP screen measures the level of a protein called alpha-fetoprotein (AFP), which is made naturally by the fetus and placenta. During pregnancy, a small amount of AFP normally crosses the placenta and enters the mother’s bloodstream. If abnormally high levels of this protein appear in the mother’s bloodstream, it may indicate that the fetus has an “open” (not skin-covered) neural tube defect. The MSAFP test, however, is not specific for spina bifida and requires correct gestational dates to be most accurate; it cannot definitively determine that there is a problem with the fetus. If a high level of AFP is detected, the doctor may request additional testing, such as an ultrasound or amniocentesis to help determine the cause.

The second trimester MSAFP screen described above may be performed alone or as part of a larger, multiple-marker screen. Multiple-marker screens look not only for neural tube defects, but also for other birth defects, including Down syndrome and other chromosomal abnormalities. First trimester screens for chromosomal abnormalities also exist but signs of spina bifida are not evident until the second trimester when the MSAFP screening is performed.

Amniocentesis—an exam in which the doctor removes samples of fluid from the amniotic sac that surrounds the fetus—may also be used to diagnose spina bifida. Although amniocentesis cannot reveal the severity of spina bifida, finding high levels of AFP and other proteins may indicate that the disorder is present.

Can the disorder be prevented?

Research has shown that taking folic acid before and during early pregnancy can help to reduce the risk of having a baby with spina bifida and other neural tube defects. Women who are planning to become pregnant or who are in the early stages of pregnancy should take a daily vitamin supplement that contains at least 400 micrograms of folic acid. Some women may be advised to take a higher dose of folic acid, especially if they have a history of neural tube defects in previous pregnancies.

In addition to taking folic acid supplements, women can also obtain folic acid from their diet. Foods rich in folic acid include leafy green vegetables, citrus fruits, beans, and fortified cereals.

It is important to note that not all cases of spina bifida can be prevented with folic acid. Some cases may be due to genetic factors or other causes that are not yet understood. However, ensuring adequate folic acid intake is a simple and effective way to reduce the overall risk of neural tube defects.

What are the treatments for spina bifida?

There is no cure for spina bifida, but various treatments are available to help manage the condition and improve the quality of life for those affected. Treatment depends on the severity and type of spina bifida, and may include surgery, physical therapy, occupational therapy, and assistive devices. Some individuals with spina bifida may require ongoing care and support throughout their lives.

Surgery is often performed shortly after birth to close the opening in the spine and minimize the risk of infection. In some cases, surgery may also be performed before birth (fetal surgery) to repair the opening in the spine. Fetal surgery for spina bifida is a complex and specialized procedure that has been shown to improve outcomes in some cases, but it is not suitable for all pregnancies. The decision to undergo fetal surgery depends on several factors, including the severity of the defect, the health of the mother and fetus, and the availability of specialized medical facilities.

Physical therapy and occupational therapy can help individuals with spina bifida develop and maintain muscle strength, improve coordination, and learn to perform daily tasks independently. These therapies can be started early in life and may need to be continued throughout the individual's life, depending on the severity of the condition.

Assistive devices, such as braces, crutches, or wheelchairs, can help individuals with spina bifida achieve greater mobility and independence. Adaptive equipment, such as modified utensils, seating systems, or communication devices, may also be helpful in improving daily functioning.

In some cases, individuals with spina bifida may require additional surgeries or medical interventions to address complications or secondary conditions, such as hydrocephalus, Chiari II malformation, or orthopedic issues.

Regular medical check-ups and ongoing monitoring are important for individuals with spina bifida to ensure that any potential issues are addressed promptly and that appropriate interventions are implemented as needed.

What is the prognosis for individuals with spina bifida?

The prognosis for individuals with spina bifida varies widely and depends on the severity of the condition, the presence of associated complications, and the effectiveness of treatment interventions. Many individuals with spina bifida, particularly those with milder forms, can lead active, productive lives with appropriate medical care and support.

Advancements in medical care and early intervention have significantly improved the quality of life and life expectancy for individuals with spina bifida. However, some individuals with more severe forms of the condition may face significant challenges, including ongoing medical issues, mobility limitations, and the need for lifelong care and support.

It is important for individuals with spina bifida and their families to work closely with a team of healthcare professionals, including doctors, therapists, and educators, to develop a comprehensive care plan that addresses the individual's unique needs and promotes optimal health and well-being.

Can the disorder be prevented?

Folic acid, also called folate, is an important vitamin in the development of a healthy fetus.   Although taking this vitamin cannot guarantee having a healthy baby, it can help.  Recent studies have shown that by adding folic acid to their diets, women of childbearing age significantly reduce the risk of having a child with a neural tube defect, such as spina bifida.  Therefore, it is recommended that all women of childbearing age consume 400 micrograms of folic acid daily.  Foods high in folic acid include dark green vegetables, egg yolks, and some fruits.   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.   

Women 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 spina bifida or another neural tube defect; 5-10 times the risk to the general population.  These women may benefit from taking a higher daily dose of folic acid before they consider becoming pregnant.

What is the prognosis?

Children with spina bifida can lead active lives.  Prognosis, activity, and participation depend on the number and severity of abnormalities and associated personal and environmental factors.  Most children with the disorder have normal intelligence and can walk, often with assistive devices.  If learning problems develop, appropriate educational interventions are helpful.

Resources

If you or a loved one is affected by spina bifida, there are numerous organizations and support groups that can provide information, resources, and assistance. Some of these organizations include:

• Spina Bifida Association (SBA)
• March of Dimes
• Christopher and Dana Reeve Foundation

These organizations can offer valuable information on spina bifida, as well as support and advocacy for individuals and families affected by the condition.

Spina bifida Resources
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