Definition Spina bifida is a type of birth defect that causes abnormal formation of the spinal column.
What is going on in the body? The spinal column is a series of bones stacked on top of each other. There is a canal, or opening, in the centre of these bones. This canal contains the spinal cord, a protective membrane around the cord, and many nerves. In spina bifida, the rear part of the spinal canal does not develop properly. This leaves an opening in the spinal column, which may cause problems in the nervous system. This most often occurs in the lower back, but any part of the spinal column may be affected. There are three common forms of spina bifida:
Spina bifida occulta is the most common and least severe form of spina bifida. The rear part of the spinal column usually has only a small opening. The spinal cord and the protective membrane usually remain in their proper place.
Meningocele is the least common of the three forms. The rear part of the spinal column has a larger opening. The protective membrane around the cord sticks out through the spinal column. The spinal cord and nerves usually remain in place.
Myelomeningocele is the most severe form of this condition. The rear part of the spinal cord has a larger opening. The protective membrane and the spinal cord or some nerves stick out through the opening.
What are the signs and symptoms of the condition? Examination of a newborn infant with spina bifida may show different things. This depends on the form, location, and severity of the condition:
Spina bifida occulta often has no findings at all. It may not be noticed until much later in life. Some children have a wisp of hair, a dimple, or a soft swelling in the skin over the area of the spinal canal defect.
Meningocele may show obvious swelling in the skin over the area of the spinal column defect. The skin may even be missing. Many newborns have no other symptoms, although severe cases may cause problems in the nervous system. These can cause paralysis and loss of feeling.
Myelomeningocele defects are usually the most obvious. A large swelling of the skin over the spinal column may occur, if the skin is present at all. Nervous system problems are usually found. These may include paralysis and loss of feeling. Constant dribbling of urine and leakage of stool may be present. If the defect is high up in the neck, an enlarged head and breathing troubles may occur.
What are the causes and risks of the condition? Both genes and the environment are thought to play a part in causing spina bifida. For example, white women have affected children more often than black women. The following factors increase the risk of a woman having a child with spina bifida:
having a previous child with spina bifida, which increases the risk greatly for future children.
nutrition problems, especially a deficiency of folic acid. An excess of vitamin A may also cause this condition.
taking certain medications during pregnancy. Examples include medications used to control seizures, such as tegretol.
a family history of spina bifida, either in the woman or her partner.
What can be done to prevent the condition? Research has shown that many cases of spina bifida can be prevented if women get enough daily folic acid. This prevention is needed before becoming pregnant and during at least the first 12 weeks of pregnancy. The folic acid may come from foods fortified with folic acid and from folic acid supplements.
Because many pregnancies are unplanned, all women who may get pregnant are advised to get at least 400 micrograms of folic acid daily. Prevention is often most effective before a woman knows she is pregnant. Those who already have an affected child may benefit from taking more folic acid and should speak with their doctor. However, at least 30% of neural tube defects are unrelated to getting enough folic acid.
Women taking medications to prevent seizures or drugs with vitamin A, which are commonly used for acne, should discuss pregnancy with their doctor. Vitamin A supplements should be avoided by pregnant women and women trying to get pregnant.
How is the condition diagnosed? Some cases of this condition can be diagnosed before a child is born. A blood test in the mother at about the fifth month of pregnancy can be abnormal if a child has spina bifida. Further testing is needed if the blood test is abnormal. A special test known as ultrasound can be used to look at the baby inside the womb. Severe defects may be seen with this test. Another procedure, amniocentesis, may be done. This involves getting a sample of the fluid that surrounds the baby in the womb. A needle is inserted through the skin of the mother's belly and into the womb. Fluid is then taken out and sent to the laboratory for testing. The results of testing are often abnormal if a child has this condition.
This condition may or may not be obvious during a physical examination at birth. If a defect is seen or suspected, further special X-ray tests are often used to define the exact defect.
What are the long-term effects of the condition? Long-term effects depend on the severity and location of the defect. There may be no long-term effects at all, or death may occur. Severe nervous system damage is possible. This may cause seizures, mental retardation, paralysis, weakness, loss of sensation, permanent inability to control the bowels or bladder, and other problems. Infection of the nervous system may also occur and can lead to death. The emotional impact on the family can be devastating if a child is severely affected.
What are the treatments for the condition? Treatment depends on the severity and location of the defect. Mild forms of the condition may not require treatment. Severe defects may require immediate surgery after birth and intense treatment for the rest of the person's life. The presence of a meningocele or myelomeningocele often means that surgery will be needed at some point. Special drainage tubes may be put into the brain. They keep the head from enlarging in some cases. Surgery cannot correct damage to the nervous system. The purpose of surgery is to cover any defects with skin so that infection can be avoided. Surgery can also help to correct problems in other organ systems.
What are the side effects of the treatments? All surgery carries a risk of bleeding, infection, and reactions to the anaesthesia medication. Specific side effects depend on the type of surgery.
What happens after treatment for the condition? This depends mostly on the amount of damage to the nervous system and other organs. The greater the damage, the longer and more intensive the treatment must be. Some people may need treatment for life.
How is the condition monitored? Parents can help monitor the symptoms. The doctor also uses the physical examination to monitor the condition. Ongoing care and monitoring depend on the needs of the child.
Author: Adam Brochert, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 9/1/2005 Contributors Potential conflict of interest information for reviewers available on request
