Spina Bifida
Neural Tube Birth Defects

Birth Defect Guide


Spina Bifida


What Is Spina Bifida?
Types & Symptoms
How Is It Diagnosed?
How Is It Treated?
What Are The Causes and Risk Factors?
Can It Be Prevented?

What Is The Life Expectancy Of A Child Born With It?

Guide To Defects
Birth Defects

What Is Spina Bifida?

Spina bifida is a birth defect where the spinal cord fails to develop properly while the baby is still growing in the womb. It is one of the most common types of neural tube defects. A neural tube defect occurs during pregnancy as a result of abnormalities in the way that the fetus develops. The neural tube develops along the back of the embryo by week 3 and it later becomes the spinal cord, the covering of the spinal cord and the brain. If this tube does not completely close a defect can occur in any of those body parts. Most commonly a defect occurs in the spinal cord and vertebrae, and this is known as spina bifida. The symptoms can range in severity from a dimpling or tuft of hair at the base of the spine, to a minor vertebrae abnormality to complete exposure of part of the spinal cord (known as myelomeningocele). It is rare for the head or brain to be affected. Spina bifida is usually detected before birth so if treatment after delivery is necessary, both parents and doctors will have time to make the necessary arrangements. While some types of the condition are relatively prevalent, since the discovery in 1992 that folic acid taken during early pregnancy provides protection against neural tube defects, the rates have been declining.

Types & Symptoms

There are two types of spina bifida: spina bifida occulta and spina bifida manifesta:

Spina Bifida Occulta
This is the mildest form of the condition and children born with this type of defect rarely have any health problems and their spinal cord is largely unaffected. In fact it can often go undiagnosed or may only be diagnosed by X-ray in adult life as the result of another minor condition such as a back or leg pain. In fact spina bifida occulta is so common that it is estimated that 40 percent of American adults have it. As complications resulting from the condition are relatively uncommon, some scientists have resorted to calling it a vertebral fusion defect in order to remove any reference to the more frightening term spina bifida.

Sometimes babies born with occulta have a small tuft of hair or dimple at the base of their spine or they have a small raised area of fat and skin over the defect. Other tell-tale signs include:
1. Mongolian Spots: Dark spots or bluish-black marks on the skin around the spine.
2. Hypopigmented Spot: An area around the spine where the skin is lighter in color.
3. Hemangioma: A red or purple spot on the skin around the spine consisting of a collection of blood vessels.
In a small number of cases, symptoms may occur which can have potential health consequences. These are:
4. Back or leg pain.
5. Orthopedic deformities in the legs, back and feet.
6. Weakness or paralysis in the legs.
7. Numbness or absence of sensation in the legs or back.
8. Change in bowel or bladder function.

Those with a likelihood of an underlying spinal cord defect should have it medically evaluated to prevent any serious problems occurring. The most obvious way of knowing who those candidates are, are those with any of the skin abnormalities listed above. These are present in about 80 percent of occulta cases.

Spina Bifida Manifesta

There are two types of spina bifida manifesta which are: myelomeningocele and meningocele. Collectively both types occur in about 1 in every 1000 births. Of those 1000 births, about 96 percent have myelomeningocele and the remaining 4 percent have meningocele.

Myelomeningocele Spina Bifida
This is the most severe form of spina bifida. It occurs when a portion of the spinal cord protrudes through the back. In some cases the cord sacs are covered with skin, in other instances the nerves are exposed. Generally when doctors refer to spina bifida, they are referring to myelomeningocele. A child born with this defect typically has some paralysis. The extent of paralysis depends on where the opening of the cord is. The higher the opening on the back, the more paralyzed the child tends to be. Those with myelomeningocele nearer the head might be paralyzed and require a wheelchair. Those affected lower down the spine might have more use of their legs and rely on crutches, leg braces or walkers for mobility. Some may even be able to walk without aids. About 80 percent of children with severe myelomeningocele also develop a buildup of fluid in the brain known as hydrocephalus which can lead to meningitis and serious infections of the brain. This is usually treated by brain surgery where a permanent shunt is inserted to drain away excess fluid. Occasionally children with myelomeningocele may also have learning difficulties.

Meningocele Spina Bifida
This is where the protective covering around the spinal cord (called meninges) pushes through the baby's back in a sac of fluid called a meningocele. As the spinal cord remains mostly unharmed, this form of spina bifida can usually be repaired without problems. Occasionally it may lead to minor disabilities.

How Is Spina Bifida Diagnosed?

It can be diagnosed during pregnancy or after childbirth. Alternatively, as in the case of occulta, it may only be diagnosed in adulthood, or never at all.

During Pregnancy

Currently women are routinely offered prenatal tests to check for birth defects. These include:

Triple Screen or Quad Screen Blood Test: You should be offered this between weeks 16 to 18 of pregnancy. The Triple Screen Test checks for AFP, HCG and Estriol and the Quad additionally checks for Inhibin-A. These simple blood tests give an accurate assessment on the presence of neural defects as well as the presence of Down syndrome and Edwards syndrome.

Ultrasound Scan: These are routinely performed before week 15, and frequently spina bifida can be seen with this test. Or it may be detected in the week 20 ultrasound scan called an anatomy scan.

Amniocentesis Test: This is an invasive test and will only usually be performed when the blood test and/or scan confirm the likelihood of spina bifida. During an amniocentesis the doctor takes a sample of amniotic fluid which surrounds the fetus in the womb. A higher than average level of AFP suggests the presence of spina bifida.

After Childbirth

Occasionally spina bifida is not diagnosed until after birth because the mother did not receive adequate prenatal care and/or an ultrasound was not carried out (or if it was, it did not show clear pictures of the affected part of the baby's spine). If there is no obvious opening in the spine, a tuft of hair or dimple on the baby's back may alert doctors. In such instances a CAT scan, X-ray or MRI scan will be performed to assess the extent of any spine deformity.

How Is It Treated?

Most cases of occulta require no treatment, even if or when diagnosed. The more serious the defects however, the more treatments the child is likely to require. Common complications which require medical intervention include:

Open Spina Bifida
This is where the baby is born with part of its spinal cord exposed (myelomeningocele). Surgeons will carry out surgery to close it shortly before birth or within a few days of childbirth.

If a baby is born with water on the brain their head can swell and become too large. This condition needs to be treated by surgery to prevent serious infections, meningitis or brain tumors. This surgery may need to be repeated as the child grows older.

Tethered Spinal Cord
This is a common issue, even in less severe cases of spina bifida. Usually the end of the spinal cord floats unhindered around the spinal canal. In the case of a tethered spinal cord, it is attached to the spinal canal. As the child grows, the spinal cord stretches which can result in permanent damage to the spinal nerves. A tethered spinal cord can cause a crooked spine (scoliosis), back pain, foot and leg weakness and changes in bowel habits. It can be treated by surgery.

What Are The Causes & Risk Factors?

Scientists still do not know the cause of spina bifida but it is suspected that both genetic and environmental factors are at play.

The risk of having a baby with spina bifida is 5 to 10 times higher if you have a first degree relative with the condition (i.e. mother, father, brother or sister). For this reason, if there is a history of the condition in the family, or you have already had children with the condition, you should consider talking to a genetic counselor. At this point in time however, genetic testing for spina bifida is still not possible. Although the MTHFR gene is being studied due its close association with folic acid metabolism, and there have been reported genetic variations of this gene in mothers with children born with neural tube defects, it is still not reliable enough to be used as a test. For tests on other common birth defects see: Down Syndrome and clubfoot. If you have any other questions, see womens health questions.

Anticonvulsant Drugs
Certain types of anticonvulsant drugs such as sodium valproate used in the treatment of epilepsy are associated with neural tube defects if taken by the mother when pregnant (as well as cleft palate defects). This is also of particular concern to those who suffer bipolar depression as this ingredient is also common in mood stabilizers. Women who take medication for migraines should also be aware of this danger. In 2001 a study was published in the New England Journal of Medicine which found, after screening 100,000 expectant women that nearly 21 percent of infants born to mothers who had taken one anticonvulsant drug during pregnancy were born with major birth defects. This rose to 28 percent if two or more drugs were taken. Where mothers had stopped taking the drugs before pregnancy the figure was 8 percent. Among the anticonvulsant drugs taken by the screened mothers were the brands Dilantin, Tegretol, Depakote, Depakene, Klonopin, Valium and Ativan.

Can Spina Bifida Be Prevented?

Research consistently shows that taking a folic acid supplement for the first 12 weeks of pregnancy can substantially reduce the risk of spina bifida in a baby. Folic acid is a B vitamin which cannot be manufactured by the body, so it needs to be taken in dietary form or via a supplement. The Centers for Disease Control and Prevention (CDC) recommend all women of childbearing age, and particularly those who want to prepare for pregnancy to take about 400 micrograms a day. To help reduce instances of birth defects, in 1998 the American FDA ruled that all cereal grains should be enriched with folic acid. A study published 4 years later showed that there were 24 percent fewer cases of the condition between 1996 and 2001, compared to previous years.

What Is The Life Expectancy Of A Child With It?

There are few clear statistics on this. In the past a child born with severe spina bifida was not expected to live much beyond their teen years. Today, due to the advancement of medical care and better understanding of associated medical problems, 90 percent of people born with the condition survive well into their 30s and possibly beyond. However they do require ongoing care in order to have a quality of life.

Related Articles on Birth Defects

For more topics associated with pregnancy, see the following:

Pregnancy Guide
Prenatal Care Guide
Paternity Testing

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