Spina bifida is a condition in which there is abnormal development of the back bones, spinal cord, surrounding nerves, and the fluid-filled sac that surrounds the spinal cord. This neurological condition can cause a portion of the spinal cord and the surrounding structures to develop outside, instead of inside, the body. The defect can occur anywhere along the spine.
What are the types of spina bifida?
The types of spina bifida include the following:
- Spina bifida occulta. A mild form of spina bifida in which the spinal cord and the surrounding structures remain inside the baby, but the back bones in the lower back area fail to form normally. There may be a hairy patch, dimple, or birthmark over the area of the defect. Other times, there may be no abnormalities in the area.
- Meningocele. A moderate form of spina bifida in which a fluid-filled sac is visible outside of the back area. The sac does not contain the spinal cord or nerves.
- Myelomeningocele. A severe form of spina bifida in which the spinal cord and nerves develop outside of the body and are contained in a fluid-filled sac that is visible outside of the back area. These babies typically have weakness and loss of sensation below the defect. Problems with bowel and bladder function are also common. A majority of babies with myelomeningocele will also have hydrocephalus, a condition that causes the fluid inside of the head to build up, causing pressure inside of the head to increase and the skull bones to expand to a larger than normal size.
What causes spina bifida?
Spina bifida is a type of neural tube defect. Neural tube defects, including spina bifida (open spine) and anencephaly (open skull), are seen in 7 out of 10,000 live births in the U.S.
During pregnancy, the human brain and spine begin as a flat plate of cells, which rolls into a tube, called the neural tube. If all or part of the neural tube fails to close, leaving an opening, this is known as an open neural tube defect (or ONTD). This opening may be left exposed or covered with bone or skin.
Anencephaly and spina bifida are the most common types of ONTD, while encephalocele (in which there is a protrusion of the brain or its coverings through the skull) is much rarer. Anencephaly occurs when the neural tube fails to close at the base of the skull, while spina bifida occurs when the neural tube fails to close somewhere along the spine.
In the vast majority of cases, an ONTD occurs without a prior family history of these defects. ONTDs result from a combination of genes inherited from both parents, coupled with environmental factors. Many factors, both genetic and environmental, contribute to their occurrence.
Some of the environmental factors that may contribute to ONTDs include obesity, uncontrolled diabetes in the mother, and certain prescription medications. According to the CDC, the occurrence rate of ONTDs can vary from state to state and from country to country.
Once a child with an ONTD has been born in the family, the chance for an ONTD to occur again is increased to 4%. It is important to understand that the type of neural tube defect can differ the second time. For example, one baby could be born with anencephaly, while a second baby could have spina bifida (not anencephaly).
Prevention of neural tube defects
Because the neural tube closes 28 to 32 days after conception and before many women are aware they are pregnant, normal development of the brain and spinal cord may be affected during these first 3 to 8 weeks of pregnancy by the following:
- Genetic problems
- Exposure to hazardous chemicals and other substances
- Lack of proper vitamins (folic acid) and nutrients in the diet
- Prescription drug and alcohol consumption
Although many factors related to the development of spina bifida, research has found that folic acid (vitamin B-9), a nutrient found in some green, leafy vegetables, nuts, beans, citrus fruits, and fortified breakfast cereals, can help reduce the risk of neural tube defects. For this reason, the American College of Medical Genetics and the CDC recommend that all women of childbearing age take a multivitamin containing folic acid. Folic acid is in prenatal vitamins. Supplementation early in pregnancy is thought to be most important. If a couple has had a previous child with an ONTD, a larger amount of folic acid is recommended and can be prescribed by the woman's doctor or health care provider. This allows the woman to take it for 1 to 2 months prior to conception, and throughout the first trimester of pregnancy, to reduce the risk of another child with ONTD. Current research is focused on looking at how genes control the formation of the neural tube. Understanding this will assist in the prevention of neural tube defects.
Additional risk factors include:
- Maternal age. Spina bifida is more commonly seen in teenage mothers.
- History of miscarriage
- Birth order. First-born infants are at higher risk.
- Socioeconomic status. Children born into lower socioeconomic families are at higher risk for developing spina bifida. It is thought that a poor diet, lacking essential vitamins and minerals, may be a contributing factor.
In recent years, pioneer surgeons have developed an experimental technique for performing surgery prenatally to correct this condition before birth.
What are the symptoms of spina bifida?
The following are the most common symptoms of spina bifida. However, each baby may experience symptoms differently. Symptoms may include:
- Abnormal appearance of the baby's back, varying from a small, hairy patch or a dimple or birthmark, to a sac-like protrusion that is found along the back bone area.
- Bowel and bladder problems (for example, constipation or incontinence)
- Loss of feeling below the area of the lesion, especially in babies born with a meningocele or myelomeningocele
- Inability to move the lower legs (paralysis)
The baby may also have other problems related to spina bifida that include the following:
- Hydrocephalus (increased fluid and pressure in the head area; occurs in about 70% to 90% of cases)
- Heart problems
- Orthopedic (bone) problems
- Lower than normal intelligence level
The symptoms of spina bifida may look like other conditions or medical problems. Always consult your baby's doctor for a diagnosis.
How is spina bifida diagnosed?
Diagnostic tests can be performed during pregnancy to evaluate the fetus for spina bifida. The tests include the following:
- Blood tests. The American College of Obstetrics and Gynecology recommends that a blood test be offered between 16 and 18 weeks to all women who are pregnant who have not previously had a child with an ONTD and who do not have a family history of ONTD. This blood test measures alpha-fetoprotein (AFP) levels and other biochemical markers in the mother's blood to determine whether her pregnancy is at increased risk for an ONTD. AFP is a protein normally produced by the fetus that crosses the placenta into the mother's blood. Generally, if a fetus has an ONTD, the alpha-fetoprotein level in the mother's blood will be increased. Although this test does not tell for certain whether a fetus has an ONTD, it will determine which pregnancies are at greater risk, so that additional testing may be performed.
- Prenatal ultrasound (also called sonography). A diagnostic imaging technique that uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels. Prenatal ultrasound may be able to detect an ONTD, and may be used to examine other organs and body systems of the fetus.
- Amniocentesis. A procedure that involves inserting a long, thin needle through the mother's abdomen into the amniotic sac to withdraw a small sample of the amniotic fluid for examination. The fluid is then tested to determine the presence of alpha-fetoprotein, which occurs with an open neural tube defect. Small or closed defects may not be picked up by this test.
Management of spina bifida
The primary goal of managing spina bifida is to prevent infection and to preserve the spinal cord and nerves that are exposed outside of the body. Specific management of spina bifida will be determined by your baby's doctor based on:
- Your baby's gestational age, overall health, and medical history
- The extent and type of spina bifida
- Your baby's tolerance for specific medications, procedures, or therapies
- Expectations for the course of spina bifida
- Your opinion or preference
A cesarean delivery is often done to decrease the risk of damage to the spinal cord that may occur during a vaginal delivery. Babies born with a meningocele or a myelomeningocele usually require care in the neonatal intensive care unit (NICU) for evaluation and for surgery to close the defect. Surgery can help manage the problems, but it cannot restore muscle function or sensation to a normal state. Surgical interventions may be needed for the following:
- Repair and closure of the lesion
- Treatment of hydrocephalus
- Orthopedic problems. Orthopedic problems may include curvatures in the back, hip dislocations, ankle and foot deformities, and contracted muscles. Babies and children with spina bifida are also very susceptible to breaking their bones since their bones may be weaker than normal.
- Bowel and bladder problems. Bowel and bladder problems may require surgery to improve function in elimination, for incontinence, constipation, or when the bladder does not empty completely.
Following surgery, you will receive instructions on caring for your baby at home. Education may include the following:
- Examining the skin, especially over bony areas, such as the elbows, buttocks, back of the thighs, heel, and foot areas. Recommendations may include changing your baby's position frequently to prevent skin breakdown and pressure sores.
- Promoting bowel and bladder function
- Ways to feed you baby and monitor your baby's nutrition
- Promoting activity and mobility
- Encouraging age-appropriate growth and development
Not all babies will require surgical repair of spina bifida. Nonsurgical management of spina bifida may include the following:
- Positioning aids (used to help the child sit, lie, or stand)
- Braces and splints (used to prevent deformity, promote support or protection)
Babies with spina bifida are at high risk for developing a latex allergy due to exposure to latex from multiple medical and surgical procedures. Precautions are taken by the health care team to reduce the baby's exposure to products that contain latex. Your baby's health care providers can help you identify products that contain latex and also find products that are latex-free.
Spina bifida is a lifelong condition that is not curable. Management often focuses on preventing or minimizing deformities and maximizing the child's capabilities at home and in the community. Positive reinforcement will encourage the child to strengthen his or her self-esteem and promote as much independence as possible. Aggressive physical and occupational rehabilitation, as well as appropriate educational interventions through a multidisciplinary approach, can maximize the child's functional capacity.
The full extent of the problem is usually not completely understood immediately after birth, but may be revealed as the child grows and develops.
Genetic counseling may be recommended by your doctor to discuss the risk of recurrence in a future pregnancy, as well as vitamin therapy (a prescription for folic acid) that can decrease the recurrence risk for ONTDs. Supplemental folic acid if taken one to two months prior to conception and throughout the first trimester of pregnancy has been found to decrease the reoccurrence of ONTDs for couples who have had a previous child with an ONTD.