Surgery of Fetus Reduces Spina Bifida Complications

Surgery of Fetus Reduces Spina Bifida Complications

The Management of Myelomeningocele Study (MOMS) is a study funded by the National Institutes of Health that was started in 2003 to compare prenatal surgery (surgery before birth) with postnatal surgery (surgery after birth) in children who had myelomeningocele (MMC), a form of Spina Bifida. Experimental studies had suggested that closing the opening on the back before a baby with MMC is born is associated with better neurological outcomes. Recently, some findings from the study were published in the New England Journal of Medicine. Click here for article (PDF)

Members of SBA's Professional Advisory Council (PAC) have reviewed these outcomes for both historical and future perspective for the Spina Bifida community. A summary of the outcomes from the study is provided below and a fuller commentary can be downloaded by clicking here.

Origins of the Study
MOMS was a scientific study designed to compare surgery before birth (also called prenatal, maternal-fetal and in-utero surgery) and surgery after birth (also called postnatal surgery) in children with Spina Bifida. It came about because doctors had noticed that nerve function in babies with Spina Bifida seemed to worsen as a pregnancy progresses. This observation suggested that the damage to the nerves of those with Spina Bifida may be a two-part process: some damage occurring when the spinal cord and associated nerves do not develop fully in the first month of the pregnancy with additional damage occurring throughout the pregnancy.

Early studies done in animals seemed to confirm that the amount of nerve damage could be lessened if the open spine was closed early in a pregnancy. This led researchers to want to compare the safety and effectiveness of prenatal and postnatal surgery.

It was determined that the study would seek to enroll 200 women who were carrying a baby affected by myelomeningocele (MMC), the most severe form of Spina Bifida. The affected pregnancies would all be diagnosed with Spina Bifida by ultrasound between the 19th and 25th weeks. In 100 cases the opening in the spine would be closed between the beginning of the 19th and the end of the 25th week of pregnancy. In the other 100 cases, the baby would have surgery to close the opening in the spine after they are born. Participating women were not "selected" for one type of surgery or the other, but rather were to be randomly assigned to one of the groups.

Over 1,085 women were screened for participation and 299 were referred to one of the three study centers for further screening. Women could be excluded from the study for maternal, obstetric, or fetal reasons; the most common of which were maternal obesity, a prior history or risk factor indicators for pre-term birth, or severe spine curvature or other anomalies not associated with Spina Bifida in the fetus. Enrollment concluded at the end of 2010 with 183 women participating in the study.

Findings
On February 9, 2011, the New England Journal of Medicine published the results of the MOMS trial. Below is a breakdown of the outcomes.

Positive Outcomes

Outcome Finding Implication
Hydrocephalus Ventricular shunts were placed less often (40%) in those treated surgically in the prenatal period than in those who had not received prenatal surgery (82%). Since the presence of hydrocephalus is associated with many negative outcomes in individuals with MMC such as learning problems and more dependence, this outcome may have significant positive implications for the future of these children.
Chiari Malformation The children who had prenatal surgery had less evidence of hindbrain herniation (downward displacement of the back of the brain) (64%) than those who had surgery after birth (96%). This suggests that closing the opening on the back before the baby is born equalizes the pressure between the brain and the lower spinal column, which allows the brain to develop in a more normal location. This may be linked with better learning in the future, but it is too early to tell.
Mobility The children who had prenatal surgery were more likely to be walking independently (42%) than those who had surgery after birth (21%). Also, children who had prenatal surgery had better motor function than what would be expected based on the level of the opening of the back. This suggests that closing the back early may prevent some secondary damage (e.g., from the spine being exposed during the entire pregnancy), which preserves nerves that are important for movement.
Intelligence No difference was found between the two groups. The follow-up was short, so this may change in the future.
Urological function These results have not yet been reported. Stay tuned!

Negative Outcomes

Outcome Finding Implication
Premature delivery Premature births (with respiratory problems) were more common in the prenatally treated group (13% were delivered before 30 weeks of gestation). The average age at delivery was 34.1 weeks for babies who had prenatal surgery compared with 37.3 weeks for those who had surgery after birth. Premature delivery is associated with serious problems such as difficulty breathing and even cerebral palsy.
Pregnancy complications One-third of mothers who had prenatal surgery had thinning of the uterus or an abnormal opening (dehiscence) where surgery was performed. Other complications included decreased fluid in the uterus, and problems with the membranes surrounding the baby. These complications may affect the mothers' ability to have subsequent pregnancies.
Tethered spinal cord Infants in the prenatal-surgery group underwent more procedures for delayed spinal cord tethering. Tethering of the spinal cord (tying down from scars) can cause additional loss of function; this could negate the advantages in mobility that were associated with prenatal treatment.

The Study in Perspective
This study is a major milestone in the treatment of children with MMC, and used methods that maximize our trust in the findings (being both valid and reliable). However, the follow-up of the babies at this point is short–many of the results were noted for children at their first birthday. Time is necessary to see how well the positive differences hold up, and to see if side effects might occur. The surgery that was performed requires a tremendous amount of training on the part of the surgeons, as well as a large support team to provide care for the unborn baby and mother after surgery. This type of surgery cannot be performed in any community hospital. The costs of the intervention when compared to the benefits have not yet been discussed. This may be important when trying to decide what type of care should be funded. Finally, the mothers who were chosen for this study were chosen to ensure the best outcomes. The findings cannot be applied to those mothers who did not meet the criteria of the study (e.g., those who are obese).

Reference

Adzick NS, et al.; the MOMS Investigators. A Randomized Trial of Prenatal versus Postnatal Repair of Myelomeningocele. N Engl J Med. 2011 Feb 9. [Epub ahead of print]