Neural Tube Defects and 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 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 ]), 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 ), 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:

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 .

There are many causes of neural tube defects.

Deficiency of a B vitamin, 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 , during pregnancy is a significant factor.

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.

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.

Neural tube defects can cause brain damage, including water on the brain (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 ), learning disabilities Learning Disorders Learning disorders involve an inability to acquire, retain, or broadly use specific skills or information, resulting from deficiencies in attention, memory, or reasoning and affecting academic... read more , and difficulty swallowing Difficulty Swallowing Some people have difficulty swallowing (dysphagia). In dysphagia, foods and/or liquids do not move normally from the throat (pharynx) to the stomach. People feel as though food or liquids become... read more .

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

Other problems, such as clubfoot Clubfoot and Other Foot Defects Clubfoot (talipes equinovarus) is a birth defect in which the foot and ankle are twisted out of shape or position. Birth defects, also called congenital anomalies, are physical abnormalities... read more , arthrogryposis Arthrogryposis Multiplex Congenita Arthrogryposis multiplex congenita refers to a group of rare disorders that develop in the womb and cause many joints to become "frozen" in position. Birth defects, also called congenital anomalies... read more (joints, usually ankles, that become frozen and cannot bend), a dislocated hip Developmental Dysplasia of the Hip Developmental dysplasia of the hip is a birth defect in which the bones in the hip are incorrectly developed. Birth defects, also called congenital anomalies, are physical abnormalities that... read more , or an abnormally curved spine that causes a humpback (kyphosis Kyphosis Kyphosis is an abnormal curving of the spine that causes a humpback. (See also Overview of Bone Disorders in Children.) The upper back normally curves forward somewhat. Some children have a... read more ), may also be present at birth. Scoliosis may develop later in some children.

Many neural tube defects can be detected before birth with prenatal screening tests Screening of the Pregnant Woman Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more .

A high level of alpha-fetoprotein in a pregnant woman's blood or in amniotic fluid may indicate a neural tube defect in the fetus. So during the second trimester, blood tests Second-Trimester Screening Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more or amniocentesis Amniocentesis Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more (removing a sample of fluid from around the fetus) may be done to measure these levels.

Prenatal ultrasonography Ultrasonography Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more may show the defect or characteristic abnormalities.

After birth, some defects are obvious during the physical examination. If newborns have abnormalities that suggest occult spinal dysraphism, ultrasonography Ultrasonography Ultrasonography uses high-frequency sound (ultrasound) waves to produce images of internal organs and other tissues. A device called a transducer converts electrical current into sound waves... read more or magnetic resonance imaging Magnetic Resonance Imaging (MRI) In magnetic resonance imaging (MRI), a strong magnetic field and very high frequency radio waves are used to produce highly detailed images. MRI does not use x-rays and is usually very safe... read more (MRI) is done to check for defects in the spine. X-rays Plain X-Rays X-rays are high-energy radiation waves that can penetrate most substances (to varying degrees). In very low doses, x-rays are used to produce images that help doctors diagnose disease. In high... read more of the spine, hips, and sometimes the legs are done.

After spina bifida is diagnosed, tests to evaluate bladder function are done. They include urinalysis Urinalysis and Urine Culture Urinalysis, the testing of urine, may be necessary in the evaluation of kidney and urinary tract disorders and can also help evaluate bodywide disorders such as diabetes or liver problems. A... read more , urine culture Urinalysis and Urine Culture Urinalysis, the testing of urine, may be necessary in the evaluation of kidney and urinary tract disorders and can also help evaluate bodywide disorders such as diabetes or liver problems. A... read more , blood tests, and ultrasonography.

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 .

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

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 needed to treat hydrocephalus, may occur and sometimes cause death in older children.

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.

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