SPINA BIFIDA
DEFINITION
Spina bifida (pronounced SPI-nuh BIFF-ih-duh) means an open or severed spine and it is one of the most serious of all birth defects. The condition may affect a small region of the spine or a much larger area. In case of spina bifida, portions of the spinal column are pushed outward, making them vulnerable to injury or infection.
DESCRIPTION
The rate of spina bifida differs considerably among various populations. It occurs in about 1 of every 700 births among whites in North America. Among African-Americans, the rate is about 1 in every 3,000 births. In some parts of Great Britain, the rate may be as high as 1 in every 100 births.
Spina bifida occurs when the spine of a fetus does not close properly. Some portion of the spinal column may protrude (stick out) from the newborn baby's back. The protrusion may form a sac that includes some part of the spine. The spinal material present in the sac can vary considerably. In some cases, it consists of the membranes that cover the spinal cord. In other cases, part of the spinal cord itself is present in the sac. In the most extreme cases, the entire spine may be exposed.
The severity of spina bifida depends on a number of factors. These factors include which part of the spine has failed to close, how badly the spine is distorted, and what other medical problems the baby may have.
CAUSES
Spina bifida is a genetic disorder that is caused by a combination of defective genes. It is one of a group of genetic disorders known as neural tube defects. The neural tube is a structure that forms very early in the life of a fetus. It eventually develops into the central nervous system of the body. The central nervous system includes the brain and the spinal cord.
Neural tube defects often appear very early, sometimes within the first three or four weeks after conception. Spina bifida occurs when the neural tube does not develop normally and the covering for the spinal cord fails to wrap completely around the spine. Open spaces develop, allowing part of the spine to stick out.
SYMPTOMS
The symptoms of spina bifida depend on the location and size of the opening. Most patients have some degree of weakness in the legs. In the most extreme cases, there may be complete paralysis. The higher up the spine the defect occurs, the more severe the disabilities a person will have.
Spina Bifida: Words to Know
- Amniocentesis:
- A medical procedure in which a sample of the fluid surrounding the fetus in a woman's womb is withdrawn and examined.
- Catheter:
- A thin tube inserted into the body to allow fluids to be sent into or taken out of the body.
- Cerebrospinal fluid (CSF):
- The fluid that surrounds tissues in the brain and spinal column.
- Computed tomography (CT) scan:
- A technique in which X-ray photographs of a particular part of the body are taken from different angles. The pictures are then fed into a computer that creates a single composite image of the internal (inside) part of the body. CT scans provide an important tool in the diagnosis of brain and spinal disorders, cancer and other conditions.
- Computerized axial tomography (CAT) scan:
- Another name for a CT scan.
- Genetic disorder:
- A medical problem caused by one or more defective genes.
- Hydrocephalus:
- An abnormal accumulation of cerebrospinal fluid (CSF) in the brain.
- Myelograph:
- A test in which a dye is injected into the spinal column to allow examination of the spine with X rays or a CT scan.
- Neural tube:
- A structure that forms very early in the life of a fetus and eventually develops into the central nervous system of the body.
- Ultrasound test:
- A medical procedure in which a sound wave is transmitted into a pregnant woman's womb. The reflections produced from the sound wave can be studied for the presence of abnormalities in a fetus.
People with spina bifida often have severe bowel and bladder problems related to the spinal cord's inability to send the signals necessary for emptying them. Difficulty in emptying the bladder can lead to serious, even life-threatening infections of the kidney.
Another complication of spina bifida may be hydrocephalus (pronounced (HI-droh-SEF-uh-luss). Hydrocephalus is also known as water on the brain. The fluid present in hydrocephalus is not water, but cerebrospinal fluid (CSF). CSF is a liquid that surrounds tissues in the brain and spinal cord. Spina bifida may force large amounts of CSF into the brain. The excess fluid causes pressure on the brain, damaging brain tissue.
Many children with spina bifida also have other problems with bone structure. These problems may include clubfeet, hip dislocation, and abnormal curves and bends in the spinal column.
Intelligence in patients with spina bifida varies widely. Though people with the disease might have normal intelligence, in some cases the disease can cause severe mental retardation.
DIAGNOSIS
The sac formed as a result of spina bifida may be quite large or very small. In the mildest cases, it may be confused with a tumor. When the sac is not obvious, other clues to the disorder include the presence of a birthmark on the spine (called a port wine stain) or growth of hair in the injured region. Babies with spina bifida may also exhibit weak muscles and poor reflexes.
GENETIC TESTING
Spina bifida is one of many genetic disorders. Such disorders develop before a child is ever born. What difference would it make if parents knew that their child had a genetic disorder before the child was born?
Until recently, there was no point in asking that question. Doctors had no way of knowing whether or not a baby would be born with a genetic disorder.
But that situation has changed. Today, it is possible to identify many genetic disorders while a fetus is still in the womb. For example, a small sample of the fluid surrounding the fetus can be withdrawn. Certain tell-tale "markers" in the fluid indicate whether or not a genetic disorder is present. Today, parents can know in advance whether or not their baby will have spina bifida.
How should parents use this knowledge? Some people want to have their baby born, no matter what health problems it may have. Other people feel differently. They do not want to subject their child to even a few weeks or days of pain and suffering.
Genetic testing can be an invaluable source of information for parents. But it can also raise some of the most difficult questions they will ever have to answer.
Tests are available for confirming the presence of spina bifida. One such test is a myelograph. In a myelograph, a dye is injected in the area around the spinal cord. The spinal cord is then observed with an X ray or a computed tomography (CT) scan, which can create a picture of internal organs. Either test will show the structure of the spinal cord in detail and gaps in the spine usually show up clearly.
Spina bifida can now be diagnosed before birth. The mother is given a blood test for a substance known as alpha-fetoprotein (AFP). AFP is always present in the blood of a pregnant woman but the presence of an abnormal fetus causes an increase in the level of AFP.
Additional tests can determine whether the abnormality involves the neural tube. During an amniocentesis (pronounced AM-nee-oh-sehn-TEE-siss) test for instance, fluid surrounding the fetus is removed and examined in order to gain further information as to the likelihood of a neural tube defect.
Finally, the fetus can be examined by ultrasound. In an ultrasound test, a sound wave is sent into the pregnant woman's womb. The sound wave bounces off the fetus. Its reflection forms a picture of the fetus that can be studied for the presence of neural tube defects. The combination of blood
tests, amniocentesis, and ultrasound tests can now diagnose over 90 percent of all neural tube defects.
TREATMENT
The first goal in treating spina bifida is to close the gap in the patient's spinal column. The decision as to how and when to perform this surgery can be very difficult, however. It depends on a number of factors, including the extent and location of injury.
Patients with spina bifida may require other operations to deal with complications of the disorder. Surgery may be needed to correct clubfeet, hip dislocations, and other disorders of the skeleton. In addition, children with hydrocephalus may require the installation of a drainage tube in the brain to relieve fluid pressure.
Children with spina bifida may also require the insertion of a catheter. A catheter is a thin tube inserted into the bladder, which can empty the bladder when the patient can not. Problems with bowel movements may require high-fiber diets, laxatives, or enemas to avoid blockage of the bowel.
PROGNOSIS
The outlook for children with spina bifida varies widely depending on the severity of the condition. Improved surgical procedures have saved the lives of many children. In many cases patients can live relatively normal, well-adjusted lives.
On the other hand, the prognosis is not very promising for children with severe forms of spina bifida. The children most at risk are those who are completely paralyzed, have serious infections of the spinal cord, or have hydrocephalus or other birth defects.
PREVENTION
There is no known way to prevent spina bifida. Some research suggests, however, that the risk for neural tube defects can be reduced with folic acid therapy. Folic acid is a member of the vitamin B family. Studies have shown that pregnant women who take small amounts of folic acid have reduced risk for having children with neural tube defects.
Spinal bifida can also be prevented if parents make birth decisions based on blood tests, amniocentesis, and ultrasound tests. These tests can determine with a high degree of reliability if a fetus has neural tube defects. Parents can use this information to make decisions about the future of the fetus.
FOR MORE INFORMATION
Books
Lutkenhoff, Marlene, ed. Spinabilities: A Young Person's Guide to Spina Bifida. Bethesda, MD: Woodbine House, 1997.
Sandler, Adrian. Living With Spina Bifida: A Guide for Families and Professionals. Chapel Hill: University of North Carolina Press, 1997.
Periodicals
Kolata, Gina. "Vitamin Can Avert Birth Defect, But Message Goes Unheeded." New York Times (March 4, 1995): pp. 5+.
Organizations
March of Dimes Birth Defects Foundation. 1275 Mamaroneck Ave., White Plains, NY 10605. (800) 367–6630.
Spina Bifida Association of America. 4590 MacArthur Blvd., NW, Suite 250, Washington, DC 20007–4266. (800) 621–3141.