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Neural Tube Defects and Spina Bifida


Stephen J. Falchek

, MD, Nemours/Alfred I. duPont Hospital for Children

Reviewed/Revised Jul 2023
Topic Resources

Neural tube defects are a certain type of birth defect of the brain, spine, and/or spinal cord.

  • Neural tube defects can result in nerve damage, learning disabilities, paralysis, and death.

  • The diagnosis can be made before birth and is based on a blood test, an amniotic fluid test, or an ultrasound.

  • After birth, doctors do a physical examination and may do additional imaging tests.

  • Folate (folic acid) taken by the mother before conception and during the first trimester can help prevent these defects.

  • Surgery usually is needed to close neural tube defects.

Spina Bifida

Spina bifida is a neural tube defect. Although spina bifida can be serious, people who have it may live a long life.

Spina bifida results when the neural tube fails to close completely and remains an open channel. In spina bifida, the bones of the spine (vertebrae) do not close over the spinal cord. It most commonly affects the spine in the lower back. One or more of the vertebrae may be involved.

Spina bifida occulta is the mildest form of spina bifida. Typically, only the bone at the back of the vertebra (one of the bones that make up the backbone) is affected and the spinal cord and meninges are unaffected.

This common defect is called "occulta" because it is hidden (covered) by a layer of skin. This skin layer typically appears normal, but sometimes it is a different color than the surrounding skin, or there may be a small tuft of hair overlying the defect.

Spina bifida occulta usually causes no symptoms but can be associated with other birth defects or with abnormalities of the spinal cord (occult spinal dysraphism).

Occult spinal dysraphism is a form of spina bifida in which the spinal cord is affected. In occult spinal dysraphism, newborns may have visible abnormalities on their lower back. These include birthmarks, overly pigmented areas (hemangiomas Hemangiomas of infancy (also called strawberry or infantile hemangiomas) Hemangiomas are abnormal overgrowths of blood vessels that can appear as red or purple lumps in the skin and on other parts of the body. (See also Overview of Skin Growths and Overview of Growths... read more Hemangiomas of infancy (also called strawberry or infantile hemangiomas) and flame nevus [ stork bite Port-Wine Stains Port-wine stains are flat pink, red, or purplish discolorations present at birth due to malformed blood vessels. (See also Overview of Skin Growths and Overview of Growths and Malformations... read more Port-Wine Stains ]), tufts of hair, openings in the skin (dermal sinus), or small lumps (masses). The underlying spinal cord may have a defect, such as a fatty tumor (lipoma Lipomas Lipomas are soft deposits of body fat that grow under the skin, causing round or oval lumps. (See also Overview of Skin Growths.) Lipomas are very common. They appear as smooth, soft bumps under... read more Lipomas ), or the band that anchors the spinal cord (filum terminale) may be thickened and short, causing the cord to be stretched and unable to move normally within the spinal canal. As the child grows, the spinal cord must be able to move freely inside the spinal canal. If not treated, this problem with the cord can lead to nerve damage that results in a loss of bladder and bowel control, leg weakness, and spasm of leg muscles, which can eventually lead to an inability to walk.

Spina bifida cystica is the most serious form of spina bifida. In spina bifida cystica, tissues of the meninges, spinal cord, or both protrude through the opening in the vertebrae. A thin membrane of skin may cover the tissues, or they may not be covered by skin.

Spina bifida cystica has the following categories:

  • A meningocele: Only the meninges protrude

  • A meningoencephalocele: The meninges and brain tissue protrude

  • A meningomyelocele: The meninges and spinal cord tissue protrude

  • An encephalocele: Only brain tissue protrudes

  • A myelocele: Only spinal cord tissue protrudes

Damage to brain or spinal cord tissue is much more likely when tissue protrudes outside the normal contour of the back, especially if there is no normal skin covering the protruding tissue. Also, when spinal cord tissue or meninges are fully exposed, they may become infected by bacteria, causing meningitis Meningitis in Children Bacterial meningitis is a serious infection of the layers of tissue covering the brain and spinal cord ( meninges). Bacterial meningitis in older infants and children usually results from bacteria... read more .

Spina Bifida: A Defect of the Spine

In spina bifida, the bones of the spine (vertebrae) do not form normally. Spina bifida can vary in severity.

In occult spinal dysraphism, one or more vertebrae do not form normally, and the spinal cord and the layers of tissues (meninges) surrounding it may also be affected. There are several types with differing neurologic severities. The diagnosis is sometimes suggested by symptoms in the lower back, such as a tuft of hair, a dimpling, or a pigmented area on the skin over the defect.

In a meningocele, the meninges protrude through the incompletely formed vertebrae, resulting in a fluid-filled bulge under the skin. The spinal cord is in its normal location.

The most severe type is a meningomyelocele, in which the meninges and spinal cord protrude. The affected area appears raw and red, and the infant is likely to be severely impaired.

Spina Bifida: A Defect of the Spine

Other neural tube and associated defects

Anencephaly is the most severe neural tube defect. In anencephaly, the brain tissue fails to develop. This defect is always fatal.

Chiari malformation may occur with spina bifida. In this abnormality, the cerebellum (the part of the brain that controls balance) protrudes through the opening in the bottom of the skull. The protruding cerebellum may put pressure on the brain stem or spinal cord. Children may develop hydrocephalus Hydrocephalus Hydrocephalus is an accumulation of extra fluid in the normal spaces within the brain (ventricles) and/or between the inner and middle layers of tissues that cover the brain (the subarachnoid... read more Hydrocephalus (water on the brain).

Syringomyelia Syrinx of the Spinal Cord or Brain Stem A syrinx is a fluid-filled cavity that develops in the spinal cord (called syringomyelia), in the brain stem (called syringobulbia), or in both. Syrinxes may be present at birth or develop later... read more occurs when the normally small fluid-filled central canal within the spinal cord widens and fills with a larger amount of fluid. Syringomyelia can occur with spina bifida or with Chiari malformations.

Causes of Neural Tube Defects

There are many causes of neural tube defects.

Genetic factors and use of certain medications during pregnancy (such as valproate) can make neural tube defects more likely. The defect often develops before the mother knows she is pregnant.

Symptoms of Neural Tube Defects

Many children who have minor neural tube defects have no symptoms.

Most symptoms caused by neural tube defects result from brain or spinal cord damage.

Spinal cord damage can cause severe problems, typically involving the bowels, bladder, and legs. Problems include

Diagnosis of Neural Tube Defects

  • Before birth, blood tests or amniocentesis to measure alpha-fetoprotein levels or prenatal ultrasonography

  • After birth, physical examination and additional imaging tests

Treatment of Neural Tube Defects

  • Surgery

Health care professionals, usually a team of specialists (including a neurosurgeon, a urologist, a pediatrician, a pediatric rehabilitation medicine specialist, an orthopedic surgeon, a physical therapist, a nurse practitioner, and a social worker), evaluate the type and severity of the defect and talk to the family about how treatment and care can be implemented.

Neural tube defects are usually closed surgically. Certain defects, such as a myelomeningocele, are typically repaired soon after birth. A shunt (a plastic tube that creates a permanent alternate drainage path for cerebrospinal fluid) may be placed to treat hydrocephalus Treatment Hydrocephalus is an accumulation of extra fluid in the normal spaces within the brain (ventricles) and/or between the inner and middle layers of tissues that cover the brain (the subarachnoid... read more Treatment .

Problems with the bladder, bones, or muscles and other problems are treated as needed.

Prognosis for Neural Tube Defects

With appropriate care, most children do well.

However, complications, such as loss of kidney function and problems with shunts Treatment Hydrocephalus is an accumulation of extra fluid in the normal spaces within the brain (ventricles) and/or between the inner and middle layers of tissues that cover the brain (the subarachnoid... read more Treatment needed to treat hydrocephalus, may occur and sometimes cause death in older children.

Prevention of Neural Tube Defects

  • Folate

Folate reduces the risk of neural tube defects.

All women of childbearing age who have not had an infant with a neural tube defect should take a vitamin supplement with folic acid (folate Folate Deficiency Folate deficiency is common. Because the body stores only a small amount of folate, a diet lacking in folate leads to a deficiency within a few months. Not eating enough raw leafy vegetables... read more ) beginning 3 months before getting pregnant and continuing through the first 3 months of pregnancy.

Women who have had an infant with a neural tube defect are at high risk of having another affected infant and should take high doses of folate supplements beginning 3 months before getting pregnant again and continuing through the first 3 months of pregnancy. Folate supplements may not prevent all cases of neural tube defects but can reduce the risk of neural tube defects substantially.

Did You Know...

  • Taking folate before and during pregnancy can reduce the risk of neural tube defects.

More Information

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

  • Spina Bifida Association: An organization providing support, education, and research resources and information about how to live with or care for someone who has spina bifida

  • March of Dimes: An organization for pregnant people and babies that provides support and information about how to prevent maternal health risks, premature birth, and mother and infant deaths

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