Mark Johnson, M.D., and colleagues from Children's Hospital's Center for Fetal Diagnosis and Treatment reported on the outcomes of 50 fetal surgeries for spina bifida in the September issue of the American Journal of Obstetrics and Gynecology.
The fetal surgeries were performed at Children's Hospital between 1998 and 2002. The mean gestational age of the fetuses undergoing the surgery was 23 weeks, and their mean gestational age at birth was 34 weeks.
Of the 50 fetuses, three died from complications following premature delivery. Of the remaining 47 infants, all had reversal of the hindbrain herniation, and 20 infants (43 percent) required a shunt - compared to an 85 percent rate of shunting, found in another study, for infants with spina bifida who had surgery after birth. Twenty-four of the infants (57 percent of the surviving 47) had better neurologic leg function than predicted, based on the level of the spina bifida lesion.
Hindbrain herniation occurs when a portion of the brain protrudes through the base of the skull into the spinal column. If the tissue blocks the flow of cerebrospinal fluid within the brain, excess fluid may accumulate and cause increased pressure within the brain. The protruding hindbrain tissue may also injure nerves in the spinal cord. In all the fetuses, hindbrain herniation was present before the surgery, but resolved after the surgery.
However, the authors caution that long-term studies are needed to further evaluate leg function, bladder and bowel function, and neurodevelopment beyond the infant period.
Spina bifida is the most common birth defect of the central nervous system, affecting 1 in 2,000 live births. A developmental failure early in pregnancy leaves an opening in part of the bone and tissue covering the fetus's spinal cord. The most common and most severe form of spina bifida is myelomeningocele, which may cause the child to suffer leg paralysis, lack of bowel and bladder control, and fluid pressure on the brain (hydrocephaly).
Surgery currently performed on newborns with open spina bifida lesions requires closing tissue over the defect to protect the spinal tissue. However, previous studies have suggested that neurological injury may occur before or during birth. To prevent that injury, physicians at Children's Hospital have performed surgery for spina bifida on the fetus prior to birth.
Performing the surgical closure of the spina bifida lesion in mid-pregnancy, between 20 and 25 weeks' gestation, may prevent the progressive neurological injury which occurs during the later part of pregnancy, according to the authors. They added that the potential benefits must be balanced against the risk of preterm delivery, and the surgical risks to the mother. "Following the fetal surgery, mothers remain in the Philadelphia area so we can monitor them closely until they deliver," said Dr. Johnson.
Dr. Johnson and his co-authors note in the study that they followed a "highly selected" population. The team did not operate on fetuses in whom fetal ultrasound detected irreversible neurologic damage, nor on fetuses in which the spina bifida defect occurred at a spinal level that would not be expected to cause neurological damage.
Because the current study reports only on short-term outcomes, longer-term studies are important in evaluating fetal surgery for spina bifida. The Children's Hospital of Philadelphia is currently participating in a multicenter, randomized clinical trial of the procedure, sponsored by the National Institutes of Health. That trial, which runs from 2002 through 2006, will compare the long-term outcomes of prenatal versus postnatal spina bifida repair.
In addition to Dr. Johnson, co-authors of the study, all from the Center For Fetal Diagnosis and Treatment at The Children's Hospital of Philadelphia, are N. Scott Adzick, M.D., surgeon-in-chief and director of the Center; Leslie N. Sutton, M.D., chief of Neurosurgery; Natalie Rintoul, M.D.; Timothy M. Crombleholme, M.D.; Alan W. Flake, M.D.; Lori J. Howell, R.N., M.S.; Holly L. Hedrick, M.D., and R. Douglas Wilson, M.D.
Founded in 1855 as the nation's first pediatric hospital, The Children's Hospital of Philadelphia is ranked today as the best pediatric hospital in the nation by U.S.News & World Report and Child magazine. Through its long-standing commitment to providing exceptional patient care, training new generations of pediatric healthcare professionals and pioneering major research initiatives, Children's Hospital has fostered many discoveries that have benefited children worldwide. Its pediatric research program is among the largest in the country, ranking second in National Institutes of Health funding. In addition, its unique family-centered care and public service programs have brought the 381-bed hospital recognition as a leading advocate for children and adolescents from before birth through age 19. Children's Hospital operates the largest pediatric healthcare system in the U.S. with more than 40 locations in Pennsylvania, New Jersey and Delaware.