Neural Tube Defect/Spina Bifida/Myelemengocele

What is spina bifida?

Spina bifida is a general term used to describe defects in the closure of the neural tube. Spina bifida may also be referred to as a neural tube defect.  The neural tube is the tissues of an embryo that become the brain, spinal cord and the bones surrounding each. Very soon after conception, during the third or fourth week, the neural tube has developed and the spinal column (bones) closes. In the fetus with spina bifida, the neural tube does not close completely, which leaves a gap through which organs that should be inside the body are left outside the body. neural tube defects can range in severity from minor defect with mild or no symptoms to major disorders that result in loss of bowel and bladder control, paraplegia (diminished ability to move the legs) or quadraplegia (diminished ability to move the arms and legs), to fatal disorders such as anencephaly (absence of brain and skull).

NTD are the second most prevalent birth defect in the US. It affects 1 in every 2,000 live births. There is a strong ethnic and geographic correlation with the incidence of NTD. Countries such as Great Britain, Ireland and Pakistan have the highest incidence and Finland, Japan and Israel have the lowest.  In the United States, there is a higher occurrence in the East and South with lowest incidence in the West. Hispanics, especially those born in Mexico, have an increased incidence.

Sometimes there is an incomplete closure, which results in spina bifida occulta. These have the most minimal symptoms and will not be diagnosed before birth. During the newborn exam, a tuft of hair or dimple may be noted on the lower back that when evaluated further reveals an open area in the bone covering the spinal cord.  It is estimated that approximately 10 to 30 percent of the population may have this form of NTD and many have never been diagnosed.

Spina Bifida Cystic is the general term for NTD characterized by a vertebral (backbone) defect with a cyst or sac that can contain cerebral spinal fluid, meninges (membrane that covers the spinal cord and brain) and spinal cord elements (may include the spinal cord as well as nerves). It can occur anywhere along the spinal column but is seen most often (80 percent of cases) in the lumbar (lower back) or lumbosacral (even lower down the backbone) area. This defect occurs in approximately 1 out of every 1,000 live births. 

The more specific terms for spina bifida cystic include: 

• Meningocele involves a sac that contains meninges and cerebral spinal fluid, but the spinal cord is in its normal position. These babies usually do very well with minimal residual neurologic issues.
   
• Meningomyelocele or myelomeningocele is the most common form of NTD, occurring in approximately 1 out of 500 live births. This sac contains cerebral spinal fluid, meninges and spinal cord. There will be neurologic deficits below the level of the defect, which can result in loss of feeling and paralysis. These babies many times will also have hydrocephalus.
    
•  Myeloschisis is a severe defect in which there is no covering or membranous sac, so the spinal cord is open and exposed. The spinal cord in the exposed area is a flattened mass of neural tissue. These infants have significant neurologic issues and are at risk for infection as well as associated anomalies. 
  
• Anencephaly is another type of NTD. This is a fatal condition in which the upper end of the neural tube fails to close, meaning there is no skull bone. The brain does not develop at all or only a small part of the brain develops. These babies are miscarried, stillborn, or die shortly after birth.
   
• Encephalocele is another type of NTD in which the skull bone does not close completely, leaving a hole in the skull. The brain can protrude through this hole. These babies can have surgery to put the brain back into the skull. Many will do well, but some will have residual neurologic issues. 

A neural tube defect (meningocele or meningomyelocele) can occur anywhere along the backbone. This illustration provides the names and locations of the vertebral column bones.

Prenatal Diagnosis of spina bifida:

Please note: this discussion is primarily related to diagnosis and treatment of myelomeningocele.

Spina bifida is usually discovered when an alpha feto protein lab test is abnormal and a routine ultrasound is performed.

Your obstetrician will likely refer you to a specialist that handles high-risk pregnancies. These doctors are called perinatologists. Other prenatal test may be done to confirm the diagnosis, determine if there are other associated anomalies and evaluate the size of the defect.

The method of delivery will be discussed with you. A normal or vaginal delivery is typically the preferred method, however there is some research that suggests a Caesarean section is more beneficial for the baby. The risks and benefits will be explained to you so that you can decide what is best for you and your infant.

How does spina bifida affect my baby?

The affects of spina bifida are dependent on the type, size and location of the defect, and the presence of other birth defects. If the spinal cord is displaced into the sac or left open and exposed, the nerves below this location will be more affected. Occasionally, the sac can be ruptured or leaking.  This increases the risk for trauma and infection. The most common issues involve lower limb function and bowel and bladder control. Also, NTDs often occur with hydrocephalus. These babies will be monitored closely throughout the pregnancy.

Babies with spina bifida will need surgery soon after birth, so it is best if they are born at a hospital that can care for baby and mother alike. This keeps the two of you together and avoids the trauma of having to transport the baby after birth. It is beneficial in reducing the time required to get your baby to surgery, and decreasing the chance of injury to the sac and/or its contents. Having mother and baby at the same hospital also helps with decision making, reduces the stress on the family, and allows the mother to see her baby while recovering from delivery. It is also easier for family to visit because they are not dividing their time between two hospitals.

How does spina bifida affect my pregnancy?

An NTD may be suspected when the maternal alpha feto protein is abnormal or it may be detected on a routine ultrasound. Your obstetrician will likely refer you to a perinatologist, a doctor who cares for high-risk pregnancies. The perinatologist will perform a targeted ultrasound to confirm the diagnosis and look for any other birth defects. The perinatologist may also recommend an amniocentesis to evaluate the chromosomes because spina bifida can be associated with some genetic disorders. If there is an issue with chromosomes, this can have a significant affect on prognosis and treatment options.

One benefit of knowing that your baby has spina bifida before he or she is born is that you have more time to prepare and learn about spina bifida. The birth can be planned to occur at a medical center that is equipped with neurosurgeons. These specialists can treat the baby within hours of birth and, as soon as possible,  perform surgery to close the defect and move the exposed nerves and spinal cord back inside the body where it is protected from injury and infection.

There is conflicting information regarding the best way to deliver these babies. Whether to have a planned Caesarean section or a vaginal delivery will be discussed with you. Some studies have demonstrated that the increased uterine pressure experienced during labor may cause further damage to the baby's exposed nerves. However, other studies have not shown this to be true. The risks and benefits of each method will be discussed with you prior to term so that you can make an informed decision with your perinatologist. 

Illustration of a meningomyelocele or myelomeningocele which contains cerebral spinal fluid, meninges and spinal cord.

Fetal therapy:

In recent years, an experimental procedure has been pioneered to close the defect during pregnancy. Surgery is done between the 19th and 25th week of gestation. The surgery is accomplished by opening the uterus, removing the fetus in order to close the defect, replacing the fetus inside the uterus and closing the uterus. The surgery has all the risks of any major surgery, plus it sometimes will trigger premature labor with the potential of a preterm delivery as well as maternal and/or fetal infection. 

Presently there is a randomized controlled clinical trial being conducted to evaluate the risks and benefits of surgery in utero versus waiting to treat until after birth. Research participants are randomly assigned to either the fetal therapy group or the postnatal treatment group. There are three institutions involved in this trial and thus, doing the surgery. A fourth institution is collecting the data. If you are interested in learning more about this potential treatment protocol, please let the Fetal Concerns Program staff know. The Fetal Concerns Program can provide the information you need to make contact with the research project personnel, help you with the referral process if you choose to participate in the research project and assist in making arrangements and follow-up.

How is spina bifida treated?

After delivery and until the surgery is performed, the sac is covered with warm, moist, sterile gauze and covered with plastic to hold the moisture in, which protects the sac and helps prevent dehydration of the body. The infant is positioned so that he or she does not lay on the sac. The baby will need to be positioned on his or her side or on their abdomen with the knees flexed.

An initial physical examination will be performed by the neonatologists and neurosurgeons to assess the level of function and the extent of neurological damage. The spinal column will be evaluated for abnormal alignment of the vertebrae and an ultrasound of the head will evaluate for hydrocephalus and the Arnold chiari malformation.

The baby will need surgery to close the sac and return the contents to their proper position inside the body. Until the sac is closed, the displaced tissue is at an increased risk for infection and trauma. This surgery is typically done within the first 24 to 48 hours.  Survival rate for this type of surgery is greater that 95 percent for the first 2 years of life.

If the baby has been diagnosed with hydrocephalus, surgery will be done to place a shunt to drain the cerebral spinal fluid into the abdominal cavity and relieve the pressure in the head. Initially, it may appear that there is no hydrocephalus or only mild dilation of the ventricles in the brain. For those infants who do not initially have hydrocephalus, approximately 80 to 90 percent of infants with NTD will develop hydrocephalus after the surgical repair of the defect. Shunt surgery is typically done as a second surgery often in the first week of life.

What about after surgery?

Closure of the defect on the back is typically done within hours of delivery. After surgery your baby may not be able to breathe effectively on his or her own because of the anesthesia and pain medication. A special tube called an endotracheal tube, or ETT, will be placed at the time of surgery (if it was not needed earlier) to assist with breathing. The tube is passed through the vocal cords and into the windpipe. While this tube is in place your baby will not make any sounds because of the tubes position in the vocal cords. The ETT will stay in until the baby can breath effectively on his or her own.

If hydrocephalus has been diagnosed, placement of the shunt is usually done within the first week of life. Your baby will not be able to eat for some time after surgery. An IV may also be placed in the baby's hand, arm, scalp, lower leg or foot. This is to give them medicine and for hydration when they are not able to take food by mouth because they are going to surgery. As soon as bowel function returns after surgery, the baby will be able to start eating. This may initially be accomplished with a tube that is inserted through the nose, down the esophagus and into the stomach. Some of these babies may do very well with eating and start with a bottle. Your breast milk can be given either of these ways.

While the baby is healing from surgery and learning to eat, he or she will be assessed by a variety of pediatric specialists to determine the effect the neural tube defect has had on function. A urologist will examine your baby and may order tests of bladder function. Parents may need to be taught at this time how to do "straight cathing."  This is a procedure many babies will need to continue to have done when they go home. When the baby passes urine, he or she may not be emptying their bladder completely. If they have urine sitting in there bladder for a prolonged amount of time, they can be prone to getting an infection. The straight cath will empty the bladder of any urine that is left in the bladder after the baby expels what he or she can. Sometimes the number of times a day that a straight cath is needed can be reduced or it is no longer needed at all if the amount of urine obtained with straight cathing are small. Bowel function and strength of the lower extremities will be assessed. Parents will be informed and instructed of any special measures that need to be taken in order to enhance bowel function.  Parents will also be informed and instructed in special exercises to help build strength in the lower extremities. 

If club feet are present, an orthopedist will evaluate and treat them. The feet (or foot) will be casted within that first week.  Serial casting will be done either in the hospital if the baby is still hospitalized or on an outpatient basis. If there are other issues, they will be handled by the subspecialist who is an expert in that care. 

Your baby may be on a variety of medications that can include antibiotics to fight infection, pain medication to control pain after surgery and sedation to keep him or her quiet for help in healing of the surgical site.

Your baby may look swollen after surgery. This is called edema and will go away as your baby gets stronger. Many times a catheter is placed into the bladder. This allows the Neonatal Intensive Care Unit staff to accurately measure urine output.  Urine output is one way to help with evaluating how well the baby is doing after surgery.

If your infant does not eat for a period of time, special nourishment will be given IV. Total parenteral nutrition is an IV solution that contains protein, fats, sugar, vitamins and minerals. This will supply your baby with all nutritional requirements until he or she is able to take food by mouth. 

Will I be able to care for my baby?

Yes. Please ask your baby's nurse about ways to interact with and care for your baby. If you had planned to breastfeed your baby, you can begin to pump your breast milk while you are still in the hospital. A lactation consultant can assist in answering your questions.  Your milk will be frozen and stored in the NICU until your baby is ready for it. The NICU has breast  pumps and private rooms available to you when you are visiting. You can bring in pictures, small toys, booties and blankets for your baby while he or she is in the NICU.

When can my baby go home?

Your baby will go home when he or she is eating and tolerating enough food to allow them to grow and gain weight. A baby with myelomeningocele alone and no hydrocephalus has an average hospital stay of one week, depending on their course of care. If hydrocephalus is diagnosed and a shunt is needed, the stay may average two to three weeks. If there are other health issues or complications with the shunt, the stay can be longer. Extensive follow-up and ongoing treatment is needed for these babies to optimize mobility and bowel and bladder issues. Some specialist you may see for follow-up can include neurology, orthopedics, urology, physical and occupational therapy, as well as your general pediatrician.

What is my baby's long-term prognosis?

Long-term prognosis depends on the type of NTD and the nature and extent of associated anomolies. The amount of function is dependent on the location of the defect. 

Many of these children will suffer from chronic health care issues. Some of the most common include:

• Tethered cord.
• Obesity.
• Gastrointestinal disorders.
• Urinary tract disorders.
• Learning disabilities.
• Sexual issues.
• Psychological issues.
• Latex allergies. 

With treatment, most of these children can be active and productive individuals. Despite the fact that some will have learning disabilities, approximately 70 percent will have normal intelligence. There have been concerns about depression in adulthood, but whether this is a natural part of the disease or a general complication is not clear.

If your baby is a female, she more than likely will be able to have children of her own. Her pregnancy would be high risk and she would need to consult and be followed by a perinatologist. Her risk of having a baby with spina bifida is about one in 100.

The table below describes the prognosis for walking:

Spina Bifida Level	Prognosis for Walking
S2-S4	Frequently walk without aides (braces or crutches).  May need shoe inserts.
L5-S1	Usually need short leg braces to help with foot position and push-off. May need crutches or cane.
L4	Usually need braces. May be above or below knee. May also use crutches or cane. Some use wheelchairs at older ages.
L2-L3	Long leg braces (up to thigh or waist) with crutches. May walk for exercise only in later years and use wheelchair for long distances.
L1	Long leg braces with a band around the waist. Uses crutches.  Walks for exercise only. Uses wheelchair for any distances.
T12 and above	Can be braced to walk for short distances. Uses walker or crutches. Uses wheelchair for most activities, even in childhood.

S=sacral

L=lumbar

T=thoracic

Learn more about the Spina Bifida Clinic at Children's Hospital of Wisconsin.

For future support and information visit www.sbaa.org The Spina Bifida Association of America.