Feb. 10, 2011 -- Children's odds of a good outcome from spina bifida surgery are better if the operation is done before birth, a major clinical trial shows.
But fetal surgery carries risks for the mother, and not all outcomes are good.
The findings come from an eight-year study led by Diana Farmer, MD, of the University of California, San Francisco. The study was halted early when it became clear that kids tended to do better with fetal surgery than with surgery after birth.
"Based on our findings, it appears that fetal surgery can provide a better option for these patients than waiting to treat them after birth," Farmer says in a news release.
Spina bifida is a birth defect in which the spine does not form properly. In the most common form, myelomeningocele, the partially exposed spinal cord pushes out into a sac filled with spinal fluid. The spinal cord is underdeveloped and damaged.
About 10% of these babies die. Those who survive may have lifelong disabilities that include leg weakness or paralysis and loss of bowel and bladder control.
Many of these kids also have a kind of hernia of the brain stem, in which part of the brain is pulled down into the upper spinal canal. This may lead to hydrocephalus -- a buildup of spinal fluid in the brain that must constantly be drained via a hollow tube called a shunt. The shunt is typically needed for the rest of the patient's life, and usually means periodic operations for repair or to treat infection.
In traditional surgery performed after birth, surgeons cover the baby's defect with skin. The fetal surgery is similar -- but may have the added benefit of allowing further development of the spinal cord before birth.
Fetal surgery obviously involves additional risks to both the mother and the unborn child. It's an open operation requiring a large incision. Women who undergo the procedure must deliver any future children via C-section.
"This is serious surgery, and a woman risks her life just as if she donated a piece of her liver in a living [donor] transplant operation," Farmer says.
Is the risk worth it? In the study of 183 women:
- Shunts were needed by 40% of the kids in the fetal surgery group and in 82% of those operated on after birth.
- At age 3 years, 42% of the kids in the fetal surgery group were able to walk independently, compared with 21% in the surgery-after-birth group.
- 79% of the kids in the fetal surgery group were born prematurely, compared with 15% in the surgery-after-birth group.
"Despite having more severe lesions and a nearly 13% incidence of preterm delivery before 30 weeks, the prenatal-surgery group had significantly better outcomes than the postnatal-surgery group," Farmer and colleagues report in the early online issue of the New England Journal of Medicine.
Fetal surgery for spina bifida is not an unmitigated success, note Joe Leigh Simpson, MD, of Florida International University and Michael F. Greene, MD, of Massachusetts General Hospital in an editorial accompanying the Farmer report.
Simpson and Greene note that for 10 years, all fetal surgeries for spina bifida in the U.S. were carried out by the three medical centers involved in the Farmer study. As other medical centers take on patients, surgeons may not have the same rate of success while they gain experience with the procedure.
Moreover, they write, the open surgery required for the prenatal procedure is risky -- and does not help a large proportion of kids.
"Surely the greatest benefit would derive from a less traumatic approach," Simpson and Greene write. "The still suboptimal rates of poor neonatal outcome and high maternal risk necessitate the use of less invasive approaches if such procedures are to be widely implemented."