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February 14, 2011
Surgery Before Birth Improves Spina Bifida Outcomes
Surgical repair of a spinal birth defect before birth, rather than after, can improve mobility and reduce the risk of serious complications, a new study found. The outcomes were so positive that the clinical trial was stopped early. However, the procedure does carry some risks, such as preterm birth.
The birth defect, called myelomeningocele, is the most serious form of spina bifida, a condition in which the spinal column fails to close around the spinal cord. With myelomeningocele, the spinal cord protrudes through an opening in the spine of the early embryo. After birth, the disorder often results in weakness or lower-limb paralysis. It leads to death in about 10% of affected infants.
Newborns with myelomeningocele typically undergo surgery to place the cord back into the spinal cavity and seal the opening with sutures. But studies in animals suggested that surgery in the womb might yield better outcomes.
To investigate, a multi-site team of scientists enrolled more than 150 pregnant women in a clinical trial. About half were randomly assigned to have surgery to close the spinal defect in their unborn child before the 26th week of pregnancy. The other women had the surgery performed on the child after birth. The study was funded by NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).
As described in the February 9, 2011, online edition of the New England Journal of Medicine, by 1 year of age, infants who had received prenatal surgery were less likely to need a follow-up procedure to divert, or shunt, fluid away from the brain. About 65% of infants in the prenatal surgery group needed a shunt, compared to 92% in the post-natal surgery group.
All of the babies had a condition before birth called hindbrain herniation, in which the base of the brain is pulled into the spinal canal. However, by 1 year of age, one-third of the children (36%) who had prenatal surgery no longer had evidence of hindbrain herniation, compared to 4% in the postnatal surgery group.
By 2½ years of age, the prenatal surgery had resulted in significant improvements to both mental and motor functions. Although the ability to walk depends on the location of the spinal defect, children in the prenatal surgery group were about twice as likely to be able to walk without orthotics or crutches (42%) as children who had received postnatal surgery (21%).
Scientists originally intended to enroll 200 expectant mothers in the study, but the trial was stopped early because of the benefits seen in children who received prenatal surgery. Some complications, however, were more likely in the prenatal surgery group. These babies were more likely to be born preterm, and mothers who had the surgery during pregnancy were more likely to have uterine dehiscence, a thinning or tearing at the surgical incision in the uterus.
"In spite of an increased risk for preterm birth, children who underwent surgery while in the uterus did much better, on balance, than those who had surgery after birth," says NICHD Director Dr. Alan E. Guttmacher. "However, caution is advised. Because the surgery is highly specialized, it is best undertaken in facilities with staff having experience in the procedure."