Spina bifida is a birth defect that occurs when the spine and spinal cord don't form properly. It's a type of neural tube defect. The neural tube is the structure in a developing embryo that eventually becomes the baby's brain, spinal cord and the tissues that enclose them.
Normally, the neural tube forms early in pregnancy and it closes by the 28th day after conception. In babies with spina bifida, a portion of the neural tube doesn't close or develop properly, causing defects in the spinal cord and in the bones of the spine.
Spina bifida can range from mild to severe, depending on the type of defect, size, location and complications. When necessary, early treatment for spina bifida involves surgery — although such treatment doesn't always completely resolve the problem.
Spina bifida can occur in different types: spina bifida occulta, myelomeningocele (my-uh-lo-muh-NING-go-seel) or the very rare type meningocele (muh-NING-go-seel).
Spina bifida occulta
"Occulta" means hidden. It's the mildest and most common type. Spina bifida occulta results in a small separation or gap in one or more of the bones of the spine (vertebrae). Many people who have spina bifida occulta don't even know it, unless the condition is discovered during an imaging test done for unrelated reasons.
Also known as open spina bifida, myelomeningocele is the most severe type. The spinal canal is open along several vertebrae in the lower or middle back. The membranes and spinal nerves push through this opening at birth, forming a sac on the baby's back, typically exposing tissues and nerves. This makes the baby prone to life-threatening infections and may also cause paralysis and bladder and bowel dysfunction.
Signs and symptoms of spina bifida vary by type and severity, and also between individuals.
- Spina bifida occulta. Typically there aren't any signs or symptoms because the spinal nerves aren't involved. But you can sometimes see signs on the newborn's skin above the spinal defect, including an abnormal tuft of hair, or a small dimple or birthmark. Sometimes, the skin marks can be signs of an underlying spinal cord issue that can be discovered with MRI or spinal ultrasound in a newborn.
- Myelomeningocele. In this severe type of spina bifida:
- The spinal canal remains open along several vertebrae in the lower or middle back
- Both the membranes and the spinal cord or nerves protrude at birth, forming a sac
- Tissues and nerves usually are exposed, though sometimes skin covers the sac
Doctors aren't certain what causes spina bifida. It's thought to result from a combination of genetic, nutritional and environmental risk factors, such as a family history of neural tube defects and folate (vitamin B-9) deficiency.
Spina bifida is more common among whites and Hispanics, and females are affected more often than males. Although doctors and researchers don't know for sure why spina bifida occurs, they have identified some risk factors:
- Folate deficiency. Folate, the natural form of vitamin B-9, is important to the development of a healthy baby. The synthetic form, found in supplements and fortified foods, is called folic acid. A folate deficiency increases the risk of spina bifida and other neural tube defects.
- 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 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.
- Some medications. For example, anti-seizure medications, such as valproic acid (Depakene), seem to cause neural tube defects when taken during pregnancy. This might happen because they interfere with the body's ability to use folate and folic acid.
- Diabetes. Women with diabetes who don't have well-controlled blood sugar have a higher risk of having a baby with spina bifida.
- Obesity. Pre-pregnancy obesity is associated with an increased risk of neural tube birth defects, including spina bifida.
- Increased body temperature. Some evidence suggests that increased body temperature (hyperthermia) in the early weeks of pregnancy may increase the risk of spina bifida. Elevating your core body temperature, due to fever or using a sauna or hot tub, has been associated with a possible slightly increased risk of spina bifida.
Spina bifida may cause minimal symptoms or minor physical disabilities. But severe spina bifida can lead to more significant physical disabilities. Severity is affected by:
- The size and location of the neural tube defect
- Whether skin covers the affected area
- Which spinal nerves come out of the affected area of the spinal cord
This list of possible complications may seem overwhelming, but not all children with spina bifida get all of these complications. And these conditions can be treated.
- Walking and mobility problems. The nerves that control the leg muscles don't work properly below the area of the spina bifida defect. This can cause muscle weakness of the legs and sometimes paralysis. Whether a child can walk typically depends on where the defect is, its size, and the care received before and after birth.
- Orthopedic complications. Children with myelomeningocele can have a variety of problems in the legs and spine because of weak muscles in the legs and back. The types of problems depend on the location of the defect. Possible problems include orthopedic issues such as:
- Curved spine (scoliosis)
- Abnormal growth
- Dislocation of the hip
- Bone and joint deformities
- Muscle contractures
- Bowel and bladder problems. Nerves that supply the bladder and bowels usually don't work properly when children have myelomeningocele. This is because the nerves that supply the bowel and bladder come from the lowest level of the spinal cord.
- Accumulation of fluid in the brain (hydrocephalus). Babies born with myelomeningocele commonly experience accumulation of fluid in the brain, a condition known as hydrocephalus.
- Shunt malfunction. Shunts placed in the brain to treat hydrocephalus can stop working or become infected. Warning signs may vary. Some of the warning signs of a shunt that isn't working include:
- Swelling or redness along the shunt
- Changes in the eyes (fixed downward gaze)
- Trouble feeding
- Chiari malformation type II. Chiari malformation (kee-AH-ree mal-for-MAY-shun) type II is a common brain abnormality in children with the myelomeningocele type of spina bifida. The brainstem, or lowest part of the brain above the spinal cord, is elongated and positioned lower than usual. This can cause problems with breathing and swallowing. Rarely, compression on this area of the brain occurs and surgery is needed to relieve the pressure.
- Infection in the tissues surrounding the brain (meningitis). Some babies with myelomeningocele may develop meningitis, an infection in the tissues surrounding the brain. This potentially life-threatening infection may cause brain injury.
- Tethered spinal cord. Tethered spinal cord results when the spinal nerves bind to the scar where the defect was closed surgically. The spinal cord is less able to grow as the child grows. This progressive tethering can cause loss of muscle function to the legs, bowel or bladder. Surgery can limit the degree of disability.
- Sleep-disordered breathing. Both children and adults with spina bifida, particularly myelomeningocele, may have sleep apnea or other sleep disorders. Assessment for a sleep disorder in those with myelomeningocele helps detect sleep-disordered breathing, such as sleep apnea, which warrants treatment to improve health and quality of life.
- Skin problems. Children with spina bifida may get wounds on their feet, legs, buttocks or back. They can't feel when they get a blister or sore. Sores or blisters can turn into deep wounds or foot infections that are hard to treat. Children with myelomeningocele have a higher risk of wound problems in casts.
- Latex allergy. Children with spina bifida have a higher risk of latex allergy, an allergic reaction to natural rubber or latex products. Latex allergy may cause rash, sneezing, itching, watery eyes and a runny nose. It can also cause anaphylaxis, a potentially life-threatening condition in which swelling of the face and airways can make breathing difficult. So it's best to use latex-free gloves and equipment at delivery time and when caring for a child with spina bifida.
- Other complications. More problems may arise as children with spina bifida get older, such as urinary tract infections, gastrointestinal (GI) disorders and depression. Children with myelomeningocele may develop learning disabilities, such as problems paying attention, and difficulty learning reading and math.
Folic acid, taken in supplement form starting at least one month before conception and continuing through the first trimester of pregnancy, greatly reduces the risk of spina bifida and other neural tube defects.
Get folic acid first
Having enough folic acid in your system by the early weeks of pregnancy is critical to prevent spina bifida. Because many women don't discover that they're pregnant until this time, experts recommend that all women of childbearing age take a daily supplement of 400 micrograms (mcg) of folic acid.
Several foods are fortified with 400 mcg of folic acid per serving, including:
- Enriched bread
- Some breakfast cereals
Folic acid may be listed on food packages as folate, which is the natural form of folic acid found in foods.
Adult women who are planning pregnancy or who could become pregnant should be advised to get 400 to 800 mcg of folic acid a day.
Your body 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. And 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.
It's also a good idea to eat a healthy diet, including foods rich in folate or enriched with folic acid. This vitamin is present naturally in many foods, including:
- Beans and peas
- Citrus fruits and juices
- Egg yolks
- Dark green vegetables, such as broccoli and spinach