spina bifida

 

Spina bifida


    Introduction
    What is spina bifida?
    What are the different types of spina bifida?
    What causes spina bifida?
    What are the signs and symptoms of spina bifida?
    What are the complications of spina bifida?
    How is it diagnosed?
        Prenatal diagnosis
        Postnatal diagnosis
    How is spina bifida treated?
    Can the disorder be prevented?
    What is the prognosis?
    What research is being done?
    Where can I find more information

The human nervous system develops from a small specialized plate of cells along the back of the embryo. At the beginning of development, the edges of this plaque begin to coil and move closer together, creating the neural tube, a narrow tube that closes to form the brain and spinal cord of the embryo. As development progresses, the upper part of the tube becomes the brain and the rest becomes the spinal cord. This process is usually completed on the 28th day of pregnancy. But if problems occur during this process, the result can be brain disorders called neural tube defects, including spina bifida.

What is spina bifida?

Spina bifida, which literally means "split column," is characterized by the incomplete development of the brain, spinal cord, or meninges (the protective covering around the brain and spinal cord). It is the most common neural tube defect in the United States; It affects 1,500 to 2,000 of the more than 4 million babies born annually in the country.

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What are the different types of spina bifida?

There are four types of spina bifida: occult, closed neural tube defects, meningocele, and myelomeningocele.

The occult is the most common and mildest form in which one or more vertebrae are malformed. The name "hidden" indicates that the malformation or opening in the spine is covered by a layer of skin. This form of spina bifida rarely causes disability or symptoms.

The defects of the closed neural tube make up the second type of spina bifida. This form consists of a diverse group of spinal defects in which the spine is marked by a malformation of fats, bones or membranes. In some patients there are few or no symptoms; in others the malformation causes incomplete paralysis with urinary and intestinal dysfunction.

In the third type, meningocele, the meninges protrude from the spinal opening, and the malformation may or may not be covered by a layer of skin. Some patients with meningocele may have few or no symptoms while others may have symptoms similar to closed neural tube defects.

Myelomeningocele, the fourth form, is the most severe and occurs when the spinal cord is exposed through the opening in the spine, resulting in partial or complete paralysis of the parts of the body below the spinal opening. The paralysis can be so severe that the affected individual can not walk and may have urinary and intestinal dysfunction.

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What causes spina bifida?

The exact cause of spina bifida remains a mystery. No one knows what interrupts the complete closure of the neural tube, causing a malformation to develop. Scientists suspect that genetic factors play a role,


nutritional and environmental. Research studies indicate that insufficient intake of folic acid, a common vitamin B, in the mother's diet is a key factor in the cause of spina bifida and other neural tube defects. The prenatal vitamins that are prescribed to the pregnant woman typically contain folic acid as well as other vitamins. (See "Can the disorder be prevented?" Below for more information on folic acid.)

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What are the signs and symptoms of spina bifida?

The symptoms of spina bifida vary among people, depending on the type. Often, individuals with "hidden" have no outward signs of the disorder. Often defects of the closed neural tube are recognized early in life due to the abnormal hair lock or a small dimple or birthmark on the skin at the site of the spinal malformation.

Meningocele and myelomeningocele usually involve a sac full of fluid, visible in the back, protruding from the spine. In meningocele, the sac may be covered with a thin layer of skin, whereas in most cases of myelomeningocele, there is no layer of skin covering the sac and a section of the spinal cord tissue is usually exposed.

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What are the complications of spina bifida?

The complications of spina bifida can range from minor physical problems to serious physical and mental disabilities. It is important to note, however, that most people with spina bifida have normal intelligence. Gravity is determined by the size and location of the malformation, whether it is covered or not by skin, if spinal nerves protrude from it, and what nerves are involved. Generally all the nerves located below the malformation are affected. Therefore, the higher the malformation is in the back, the greater the amount of nerve damage and the loss of muscle function and sensation.

In addition to the loss of sensation and paralysis, another neurological complication associated with spina bifida is the Chiari II malformation, a rare condition (but common in children with myelomeningocele) in which the brainstem and cerebellum or posterior portion of the brain protrudes down into the spinal canal or the neck area. This condition can lead to compression of the spinal cord and cause a variety of symptoms such as difficulty feeding, swallowing and breathing; Drowning and stiffness of the arms.

Chiari II malformation can also result in blockage of the cerebrospinal fluid, causing a condition called hydrocephalus, which is an abnormal buildup of cerebrospinal fluid in the brain. Cerebrospinal fluid is a clear fluid that surrounds the brain and spinal cord. The accumulation of fluid puts harmful pressure on the brain. Hydrocephalus is commonly treated by surgically implanting a shunt, a hollow tube, into the brain to drain excess fluid into the abdomen.

Some newborns with myelomeningocele can get meningitis, an infection of the meninges. Meningitis can cause brain damage and can be life-threatening.

Children with myelomeningocele and hydrocephalus may have learning problems, such as difficulty paying attention, problems with language and reading comprehension, and difficulty learning math.

There may be additional problems such as latex allergies, skin problems, gastrointestinal conditions, and depression as children grow up with spina bifida.

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How is it diagnosed?

In most cases, spina bifida is diagnosed prenatally, or before birth. However, some mild cases may go unnoticed until after birth, or postnatally. Very mild cases, where there are no symptoms, may never be detected.


Prenatal diagnosis

The most common screening methods used to detect spina bifida during pregnancy are the maternal serum alpha fetoprotein of the second trimester (MSAFP) and the fetal ultrasound. The MSAFP panel measures the level of a protein called alpha-fetoprotein (AFP), made naturally by the fetus and the placenta. During pregnancy, a small amount of AFP normally crosses the placenta and enters the maternal bloodstream. But if abnormal high levels of this protein appear in the maternal bloodstream, this may indicate that the fetus has a neural tube defect. The MSAFP test, however, is not specific for spina bifida, and can not categorically determine that there is a problem with the fetus. If a high level of AFP is detected, the doctor may request more tests, such as ultrasound or amniocentesis to help determine the cause.

The second quarter MSAFP panel described above can be performed alone or as part of a larger panel with multiple markers. Panels with multiple markers look not only for neural tube defects, but for other birth defects, such as Down syndrome and other chromosomal abnormalities. There are also panels for the first trimester for chromosomal abnormalities, but signs of spina bifida are not evident until the second trimester when the MSAFP panel is made.

Amniocentesis, an examination in which the doctor removes fluid samples from the amniotic sac that surrounds the fetus, can also be used to diagnose spina bifida. Although amniocentesis can not reveal the severity of spina bifida, finding high levels of AFP may indicate that the disorder is present.

Postnatal diagnosis

Mild cases of spina bifida not diagnosed during prenatal testing can be detected postnatally by radiographs during a routine examination. Doctors may use magnetic resonance imaging (MRI) or a computed tomography (CT) scan to get a clearer picture of the spine and vertebrae. Individuals with the most severe forms of spina bifida often have muscle weakness in the feet, hips, and legs. If hydrocephalus is suspected, the doctor may order a CT or x-ray of the skull to look for additional fluid in the brain.

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How is spina bifida treated?

There is no cure for spina bifida. Damaged or lost nerve tissue can not be replaced or repaired, nor can the function of damaged nerves be restored. Treatment depends on the type and severity of the disorder. Generally, children with the mild form do not need treatment, although some may need surgery as they grow.

The key priorities for treating myelomeningocele are preventing an infection in the exposed nerves and tissue from being contracted from the defect in the spine, and protecting the exposed nerves and structures from further trauma. Typically, a child born with spina bifida will undergo surgery to close the defect and prevent infection or more trauma in the first days of life.

Doctors have recently started doing fetal surgery for the treatment of myelomeningocele. Fetal surgery, performed in the uterus, involves opening the maternal abdomen and uterus and closing the opening in the spinal cord of the developing baby. Some doctors believe that the sooner the defect is corrected, the better the result will be for the baby. Although the procedure can not restore lost neurological function, it can prevent further loss. However, surgery is considered experimental and there are risks to the fetus as well as the mother.

The main risks to the fetus are those that can occur if surgery stimulates premature delivery, such as organ immaturity, brain hemorrhage, and death. The risks to the mother are infection, loss of blood that leads to the need for a transfusion, gestational diabetes, and weight gain due to rest.


Even so, the benefits of fetal surgery are promising, and include less exposure of vulnerable spinal nerve tissues and bones to the intrauterine environment, particularly amniotic fluid, which is considered toxic. As an added benefit, doctors have discovered that the procedure affects the way the brain develops in the uterus, allowing some complications-such as Chiari II with associated hydrocephalus-to correct themselves, thereby reducing, or in some cases eliminating the need of surgery to implant a shunt.

Many children with myelomeningocele develop a condition called progressive anchor, or anchored cord syndrome, where their spinal cords are fixed to an immovable structure, such as covering membranes and vertebrae, causing the spinal cord to stretch abnormally and the vertebrae to lengthen with the spinal cord. growth and movement. This condition can cause loss of muscle function in the legs, intestines and bladder. Early surgery of the spinal cord can allow the child to return to normal functioning and prevent further neurological deterioration.

Some children will need subsequent surgeries to manage problems with their feet, hips or spine. Individuals with hydrocephalus will usually require additional operations to replace the shunt, which may be small or clogged.

Some individuals with spina bifida require assistive devices such as appliances, crutches, or wheelchairs. The location of the malformation in the spine often indicates the type of assistive devices needed. Children with a high spinal defect and more extensive paralysis will often need a wheelchair, while those with a lower defect may use crutches, bladder catheters, leg braces or walkers.

The treatment of paralysis and bladder and bowel problems typically begins shortly after birth, and may include special exercises for the legs and feet to help the child prepare for walking with braces or crutches when he is older.

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Can the disorder be prevented?

Folic acid, also called folate, is an important vitamin in the development of a healthy fetus. Although taking this vitamin can not guarantee having a healthy baby, it can help. Recent studies have shown that by adding folic acid to their diets, women of childbearing age significantly reduce the risk of having a child with a neural tube defect, such as spina bifida. Therefore, it is recommended that all women of reproductive age consume 400 micrograms of folic acid daily. Foods high in folic acid include dark green vegetables, egg yolks, and some fruits. Many foods, such as some breakfast cereals, enriched breads, flours, pasta, rice, and other whole grain products, are now fortified with folic acid. Many multivitamins also contain the recommended dose of folic acid.

Women who have a child with spina bifida, have spina bifida, or have already had a pregnancy affected by any neural tube defect are at higher risk of having a child with spina bifida or other neural tube defect. These women may need more folic acid before they get pregnant.

What is the prognosis?

Children with spina bifida can lead relatively active lives. The prognosis depends on the number and severity of the abnormalities and associated complications. Most children with the disorder have normal intelligence and can walk, usually with assistive devices. If learning problems develop, early educational intervention is useful.

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What research is being done?

Within the Federal Government, the National Institute of Neurological Disorders and Stroke (NINDS), a component of the National Institutes of Health (NIH), supports and conducts research on brain and nervous system disorders that include spina bifida.



NINDS conducts research in its NIH laboratories in Bethesda, Maryland, and supports research through grants to major medical institutions throughout the country.

In a study supported by NINDS, scientists are looking at the hereditary basis of neural tube defects. The goal of this research is to find the genetic factors that make some children more susceptible to neural tube defects than others. The lessons learned from this research will fill gaps in knowledge about the causes of neural tube defects and can lead to ways to prevent these disorders. These researchers are also studying gene expression during the neural tube closure process, which will provide information about the human nervous system during development.

In addition, scientists supported by NINDS are working to identify, characterize and evaluate genes for neural tube defects. The goal is to understand the genetics of neural tube closure, and to develop information that results in improved clinical care, treatment, and genetic counseling.

Other scientists are studying the genetic risk factors for spina bifida, especially those that decrease or attenuate the role of folic acid in the mother during pregnancy, possibly leading to spina bifida in the fetus. This study will shed light on how folic acid prevents spina bifida and can lead to improved forms of folate supplements.

NINDS also supports and performs a wide range of basic research studies to understand how the brain and nervous system develop. These studies contribute to a greater understanding of neural tube defects, such as spina bifida, and offer hope for new ways of treating and preventing these disorders as well as other birth defects.

Another component of the NIH, the National Institute of Child Health and Human Development (NICHD), is conducting an extensive 5-year study to determine whether fetal surgery to correct spina bifida in the uterus is safer and more effective than traditional surgery, which is done a few days after birth. The researchers hope that this study, called the Myelomeningocele Management Study, better establishes which procedure, prenatal or postnatal, is best for the baby.