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Diseases and Conditions
Spina bifida
From MayoClinic.com
Special to CNN.com Introduction Spina bifida is a serious birth defect that occurs when the tissue surrounding the developing spinal cord of a fetus doesn't close properly. It's part of a group of birth defects called neural tube defects. The neural tube is the embryonic structure that eventually develops into the baby's brain and spinal cord and the tissues that enclose them. In normal circumstances, the neural tube forms in the developing baby early in the pregnancy and closes by the 26th day after conception. Later, the top of this tube becomes the baby's brain, and the remainder of the tube becomes the baby's spinal cord. In babies with spina bifida, a portion of the neural tube fails to develop or close properly, causing defects in the spinal cord and in the bones that make up the backbone. This can also occur in the middle or upper end of the spine but is most common in the lower spine. Spina bifida is one of the more common birth defects in the United States. When treatment for spina bifida is necessary, it's done through surgery, although such treatment doesn't always provide complete resolution of the problem. Signs and symptoms Spina bifida occurs in three forms, each varying in severity:
Causes Doctors aren't certain why neural tubes don't develop or close properly in some babies. As with many other illnesses, it appears to result from a combination of genetic and environmental risk factors, such as a family history of neural tube defects, folic acid deficiency and medical conditions such as diabetes and obesity. Risk factors Although doctors and researchers don't know for sure why spina bifida occurs, they have identified a few risk factors:
When to seek medical advice If you're a woman planning to start a family, talk to your doctor about taking a daily multivitamin containing 1 milligram (mg) of the B vitamin folic acid. Because folic acid plays a vital role in fetal development, the majority of cases of spina bifida could be prevented if all women took enough folic acid every day before and during early pregnancy. If you have known risk factors for spina bifida, talk with your doctor to determine if you should take a larger dose of prescription folic acid, even before a pregnancy begins. If you take medications, tell your doctor. Some medications can be adjusted to diminish the potential risk of spina bifida, if plans are made ahead of time. This is especially true if you have diabetes. If your baby is born with myelomeningocele, you'll likely need to consult with a multidisciplinary team of physicians, surgeons and therapists at a center that specializes in spina bifida treatment. Children with myelomeningocele require ongoing medical attention throughout their lives to monitor their condition and treat complications. Screening and diagnosis If you're pregnant, you'll be offered prenatal screening tests to check for spina bifida and other birth defects. These tests may provide reassurance that your fetus doesn't have certain serious birth defects. Or they may detect a birth defect and help you manage your pregnancy more effectively, by planning to deliver in a specially equipped medical center, for example. The tests aren't perfect. Even if the results are negative, there's still a small chance that spina bifida is present, and most mothers who have positive blood tests have normal babies. Talk to your doctor about prenatal testing, its risks and how you might handle the results. Prenatal testing is a personal choice. Blood tests Results are most accurate when the test is performed between 16 and 18 weeks of gestation, but spina bifida can't be diagnosed by blood test alone. Some spina bifida cases don't produce a high level of AFP. On the other hand, when a high level of AFP is found, a neural tube defect is present only a small percentage of the time. [8] Varying levels of AFP can be caused by other factors — including a miscalculation in fetal age or multiple fetuses — so your doctor may order a follow-up blood test for confirmation. If the results are still high, you'll need further evaluation, including an ultrasound examination. Your doctor may pair the MSAFP test with two or three other blood tests, which look for:
Depending on the number of tests, the combination is called a triple or quadruple screen. In addition to checking for neural tube defects, looking at these additional substances can help doctors determine whether chromosome abnormalities are present. Ultrasound Amniocentesis A small amount of AFP is normally found in amniotic fluid. However, when an open neural tube defect is present, the amniotic fluid contains an elevated amount of AFP because the skin surrounding the baby's spine is gone and AFP leaks into the amniotic sac. A second test can be done on the same sample to reliably confirm that a neural tube defect is present. Amniocentesis can't indicate the severity of spina bifida, however. This test does have a risk to the developing fetus. About one in 200 pregnant women miscarries after amniocentesis. Complications Spina bifida may occasionally cause only minor physical disabilities. More frequently, it leads to severe physical and mental disabilities. Factors that affect the severity of complications include:
Children with myelomeningocele may experience physical and neurological problems, including lack of normal bowel and bladder control, and partial or complete paralysis of their legs. Children and adults with this form of spina bifida might need crutches, braces or wheelchairs to help them get around, depending on the size of the opening and the care received after birth. Babies born with myelomeningocele also commonly experience accumulation of fluid in the brain, a condition known as hydrocephalus. Most babies with myelomeningocele will need a shunt — a surgically placed tube that allows fluid in the brain to drain as needed into the abdomen. This tube might be placed just after birth, during the surgery to close the sac on the lower back, or later as fluid accumulates. The majority of newborns with myelomeningocele survive. However, some may develop meningitis, an infection in the tissues surrounding the brain. Meningitis may cause brain injury and can be life-threatening. Additional problems may arise as children with spina bifida get older. Children with myelomeningocele may develop learning disabilities, including difficulty paying attention, problems with language and reading comprehension, and trouble learning math. Children with spina bifida may also suffer from latex allergies, skin problems, urinary tract infections, gastrointestinal disorders, seizure disorders, depression, and social and emotional problems. Treatment The treatment for spina bifida depends on the severity of the condition. Spina bifida occulta doesn't require treatment at all, while meningocele involves surgery to put the meninges back in place and close the opening in the vertebrae. This surgery usually occurs soon after birth. Myelomeningocele also requires surgery, usually within several hours to several days after birth. Performing the surgery early can help minimize risk of infection that's associated with the exposed nerves and may also help protect the spinal cord from additional trauma. During the procedure, a neurosurgeon places the spinal cord and exposed tissue inside the body and covers them with muscle and skin. Sometimes a shunt to control hydrocephalus is placed during the operation on the spinal cord. Sometimes the shunt placement isn't needed until weeks or months later. Ongoing care In addition, babies with myelomeningocele may require further operations for a variety of complications. Many suffer from a tethered spinal cord — a condition in which the spinal cord is bound to the scar of the closure and is less able to properly grow in length as the child grows. This progressive "tethering" can cause loss of muscle function to the legs, bowel or bladder. Surgery can limit the degree of disability and may also restore some function. Caesarean birth Prenatal surgery Proponents of fetal surgery believe that nerve function in babies with spina bifida seems to worsen rapidly after birth, so it may be better to repair spina bifida defects in utero. So far, children who received the fetal surgery seem to have better brain functioning and fewer shunts, but their bowel and bladder functioning don't seem to be improved. And the operation poses a substantial risk of death to the fetus from an extremely premature delivery. So, the question remains: Is there a real benefit to repairing myelomeningocele in utero? The National Institute of Child Health & Human Development is conducting a large, long-term clinical trial called the Management of Myelomeningocele study to try to answer that question. For now, it's unclear whether this risky technique is more effective than traditional surgery to close the spinal column after birth. Prevention Folic acid plays an essential role in a baby's development. When taken in supplement form at least one month before conception and during the first trimester of pregnancy, folic acid greatly reduces the risk of spina bifida and other neural tube defects. The key is having enough folate — the natural form of folic acid — in your system by the early weeks of pregnancy, before the neural tube closes. Because many women don't discover that they're pregnant until this time, the March of Dimes, the Centers for Disease Control and Prevention, and the Institute of Medicine recommend that all women of childbearing age take a daily supplement with 400 micrograms (mcg) of folic acid or consume breakfast cereals fortified with 100 percent (400 mcg) of folic acid per serving (Whole Grain Total, Total Raisin Bran, Smart Start, others). To find out the percentage of daily value supplied by a cereal, check its nutrition label. The Institute of Medicine advises pregnant women and breast-feeding women to up their daily folic acid intake to 600 mcg and 500 mcg, respectively. These recommendations aren't intended to prevent neural tube defects; the increased amounts are needed because your body uses extra folic acid during pregnancy and lactation. Most pregnancy experts believe supplementation of folic acid at a level of 1 mg a day — the usual dose in prescription prenatal vitamins — is the best approach for women planning pregnancy. Because high levels of folate can potentially mask a deficiency of vitamin B-12 — which can cause a condition called pernicious anemia, particularly in older adults — supplementation of dietary folic acid for the general population has been kept to a lower dose. But this risk is minimal when folic acid is used specifically while seeking pregnancy. In addition, eat a healthy diet, including foods rich in folate. This vitamin is present in many foods, including dried beans, citrus fruits, whole-grain products, and dark green vegetables such as broccoli and spinach. However, your body doesn't absorb folate as easily as it absorbs synthetic folic acid, and most people don't get the recommended amount of folate through diet alone, so vitamin supplements are necessary to prevent spina bifida. It's possible that folic acid will also help reduce the risk of other birth defects, including cleft lip, cleft palate and some congenital heart defects. Folic acid may also help protect against some forms of cancer and heart disease. When higher doses are needed Coping skills News that a newborn child has a devastating condition such as spina bifida can naturally cause parents to feel grief, anger, frustration, fear and sadness. Over time, though, many families grow to find that children with spina bifida can lead relatively active lives. Most children with spina bifida can walk for at least short distances, usually with the assistance of braces, canes or crutches, although they may require wheelchairs for longer distances. Using these devices can help a child regain mobility that was lost as a result of the condition and gain more independence. Many children with spina bifida have normal intelligence. But they may need early educational intervention for learning problems, and they may need extra help from teachers and counselors to adapt to school. A physical disability like spina bifida can also cause emotional and social problems. But children with spina bifida need encouragement to participate in activities with their peers and to lead independent lives, within their physical limitations and capabilities. If your child has spina bifida, you may benefit from finding a support group of other parents who are dealing with the condition. Talking with others who understand the challenges — and rewards — of living with spina bifida can be helpful. October 04, 2005 |