اقتراح [الأرشيف] - طـبيـعي للعلاج الطبيعي والتأهـيل الطبي

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11-26-2007, 04:28 PM

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SPINA BIFIDA

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.

Spina bifida is 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 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 of the backbone.

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 completely resolve the problem.

Causes

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 28th 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.

Doctors aren't certain why neural tubes don't develop or close properly in some babies. As with many other problems, 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:

Race. Spina bifida is more common among Hispanics and whites of Northern European descent.
***. More female babies are born with spina bifida.
Family history of neural tube defects. Couples who've had one child with a neural tube defect have a slightly higher chance of having another baby with the same defect. That risk increases if two previous children have been affected by the condition. In addition, a woman who was born with a neural tube defect, or who has a close relative with one, has a greater chance of giving birth to a child with spina bifida. However, most babies with spina bifida are born to parents with no known family history of the condition.
Folic acid deficiency. This vitamin is important to the healthy development of a fetus. Lack of folic acid (vitamin B-9) increases the risk of spina bifida and other neural tube defects.
Some medications. Anti-seizure medications, such as valproic acid (Depakene), seem to cause neural tube defects when taken during pregnancy, perhaps because they interfere with the ****'s ability to use folic acid.
Diabetes. The risk of spina bifida increases with diabetes, especially when the mother's blood sugar is elevated early in her pregnancy. Careful blood sugar control and management can decrease this risk.
Obesity. There's a link between pre-pregnancy obesity and neural tube birth defects, including spina bifida. Exactly why obese women have an increased risk of having a baby with spina bifida isn't known, but is possibly because of nutritional deficits from poor eating habits or because they may have diabetes — another known risk factor for neural tube defects.
Increased **** temperature. Some evidence suggests that increased **** temperature (hyperthermia) in the early months of pregnancy may increase the risk of spina bifida. Elevating your core **** temperature by about 2 degrees Celsius — about 3 to 4 degrees Fahrenheit above normal — due to fever or the use of saunas and hot tubs, which can raise **** temperature, have been associated with increased risk of spina bifida.

Signs and symptoms

Spina bifida occurs in three forms, each varying in severity:

Spina bifida occulta. This mildest form results in a small separation or gap in one or more of the vertebrae of the spine. Because the spinal nerves usually aren't involved, most children with this form of spina bifida have no signs or symptoms and experience no neurological problems.

An abnormal tuft of hair, a collection of fat, a small dimple or a birthmark on the newborn's skin above the spinal defect may be the only visible indication of the condition. In fact, most people who have spina bifida occulta don't even know it, unless the condition is discovered during an X-ray for unrelated reasons.

Meningocele. In this rare form, the protective membranes around the spinal cord (meninges) push out through the opening in the vertebrae. Because the spinal cord develops normally, these membranes can be removed by surgery with little or no damage to nerve pathways.
Myelomeningocele. Also known as open spina bifida, myelomeningocele is the most severe form — and the form people usually mean when they use the term "spina bifida."

In myelomeningocele, the baby's spinal canal remains open along several vertebrae in the lower or middle back. Because of this opening, both the membranes and the spinal cord protrude at birth, forming a sac on the baby's back. In some cases, skin covers the sac. Usually, however, tissues and nerves are exposed, making the baby prone to life-threatening infections.

Neurological impairment — often including loss of movement (paralysis) — is common. So are bowel and bladder problems, seizures and other medical complications.

ComplicationsSpina 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:

The size and ******** of the neural tube defect
Whether skin covers the affected area
Whether spinal nerves come out of the affected area of the spinal cord
Complications may include:

Physical and neurological problems. This may include lack of normal bowel and bladder control, and partial or complete paralysis of the 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.
Hydrocephalus. 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.
Meningitis. Some babies with myelomeningocele may develop meningitis, an infection in the tissues surrounding the brain. Meningitis may cause brain injury and can be life-threatening.
Other complications
Additional problems may arise as children with spina bifida get older. Children with myelomeningocele may develop learning disabilities, including difficulty paying attention, problems with ******** and reading comprehension, and trouble learning math. Children with spina bifida may also suffer from latex allergies, skin problems, urinary tract infections, gastrointestinal disorders, depression, and social and emotional problems.
Treatment

Currently, there is no cure for spina bifida, but there are a number of treatments available to help manage the disease and prevent complications.

Initial goals of treatment include reducing neurological damage to your child, minimizing complications such as infections and helping your family learn about and cope with the disorder.

Treatment may include ongoing surgery, medications, physical therapy and behavioral therapy, and depends on the type and severity of the defect, the childs age and overall health as well as their personal preferences.

Children with the mildest form of the disease, spina bifida occulta, usually do not require treatment. Children with spina bifida meningocele can typically be treated without surgery. However, these children may develop complications, such as bladder problems and hydrocephalus that occurs when excess fluid collects in the brains ventricles. If untreated, it may cause motor or movement disorders or mental retardation. Fluid can be drained from the brain through a surgical procedure that uses a special tube called a shunt. The shunt runs under the skin into the abdomen and the fluid passes into the child's **** without harm.

Myelomeningocele, the most severe form of spina bifida, generally requires surgery to correct the spinal defect and prevent infections, as well as further injury or trauma to the exposed spinal cord and nerves. Pediatric surgeons at UCSF Children's Hospital are involved in a five-year clinical trial, sponsored by the National Institutes of Health (NIH), to study surgery before birth as well as surgery after birth to determine the best treatment for spina bifida. For more information about this study, visit this *** site. The study is slated to continue through 2008.

The majority of babies with myelomeningocele also develop hydrocephalus, which requires treatment. Children with this form of spina bifida may also develop a progressive tethering of the spinal cord, in which the spinal cord and vertebrae do not stretch and grow normally as the child grows. This may cause loss of muscle function to the legs, bowel and bladder. Surgery on the spinal cord may be performed to help restore function. Children with bladder function problems are treated by a urologist, who may suggest catheterization, involving a small tube inserted into the bladder to help drain urine.

Many children with spina bifida experience partial or complete paralysis and require devices such as braces, crutches or wheelchairs. These children work with specialists in orthopedics and physical therapy to learn special muscle strengthening exercises. Some children may also need surgery on the hips, legs and feet.

Many children with spina bifida develop an allergy to latex, or natural rubber, which may be caused by early exposure during surgeries and medical procedures. If your child is affected by this allergy, avoid exposing them to latex products, such as baby bottle nipples, pacifiers and balloons. There are latex-free options for many products.

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.

How much folic acid to take
It's critical to have enough folic acid in your system by the early weeks of pregnancy, before the neural tube closes to prevent spina bifida. 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. To find out the percentage of Daily Value supplied by a cereal, check its nutrition label. Folic acid may be listed as folate, which is the natural form of folic acid found in food.

Most pregnancy experts believe supplementation of folic acid at a level of 1 milligram (mg) a day — the usual dose in pre******ion 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 **** 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.

When higher doses are needed
If you have spina bifida or if you have a child with spina bifida, you'll need extra folic acid before you become pregnant. If you're taking anti-seizure medications or you have diabetes, you may also benefit from a higher dose of this B vitamin. In these cases, the recommended dose of folic acid may be up to 4,000 mcg (4 mg) beginning one month prior to conception and during the first few months of pregnancy.

If you think you might need this increased amount of folic acid, ask your doctor for a pre******ion dose of the vitamin. Don't simply take extra multivitamins because the additional amounts of other vitamins may be harmful to you and your baby.