Researchers found that fetuses with enlarged ventricles were more likely to require a second surgery to relieve a life-threatening build-up of pressure within the brain. Given the risks that fetal surgery poses for mother and newborn, the findings indicate that, in these cases, it may be better to wait until after birth to perform the corrective spinal surgery.
In 2011, the Management of Myelomeningocele (MOMS) study showed that surgically correcting the spinal defect while the fetus is in the womb greatly reduces the need to divert fluid away from the ventricles to relieve hydrocephalus.
In the current analysis of data from the original MOMS study, Noel B. Tulipan, MD, Vanderbilt University Medical Center, Nashville, Tennessee, and colleagues found that fetuses who had larger ventricles were equally as likely to require placement of a shunt during the first year after birth, regardless of when they underwent the spinal repair surgery.
“These results indicate that physicians should proceed with caution before recommending in utero surgery for a fetus with enlarged ventricles,” said Rosemary Higgins, MD, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), part of the National Institutes of Health (NIH), Bethesda, Maryland.
The original MOMS study found that infants who had undergone the surgery before birth were more likely to walk without crutches or other devices. At 30 months of age, the fetal surgery group also had higher scores in tests of mental and motor development. However, as with any surgery, the procedure presented risks. Babies who underwent surgery in the uterus were more likely to be born preterm than were those who had the surgery after birth. In addition, mothers in the fetal surgery group were at risk for having the surgical scar on the uterus tear or rupture during subsequent pregnancies.
“A major rationale for performing the surgery is to avoid having to place a shunt later on,” explained Dr. Higgins. “If it’s likely that a second surgery will be needed anyway, then it doesn’t appear that the potential benefits of an initial fetal surgery outweigh the risks.”
For the current analysis, researchers tabulated the results in a single, composite outcome, to highlight the differences between treatment and control groups. The primary combined outcome for this analysis was whether a child had died, had a shunt placed in the first year after birth, or met the study’s criteria for when to place a shunt.
Dr. Higgins explained that when the researchers began the original study, there were no formal recommendations for shunt placement, so the researchers developed a set of objective criteria to guide the treatment of patients in the study.
Of the women who took part in the study, 91 were randomised to the prenatal surgery group and 92 to the postnatal group. Of these, 72.5% in the prenatal surgery group and 97.8% in the postnatal surgery group met the criteria for inclusion in the primary outcome. Overall, 44% of children in the prenatal surgery group had a shunt placed, compared with 83.7% in the postnatal group.
When the women were first enrolled in the study, the researchers took magnetic resonance imaging scans of the fetuses’ brains. Irrespective of whether they were in the prenatal or postnatal surgery group, children with the largest ventricles were more likely to require a shunt than those with smaller ventricles.
For the prenatal surgery group, shunts were eventually placed in 20% of those with ventricles <10 mm, 45.2% with ventricles from 10 to <15 mm, and 79% with ventricle size ≥15 mm. For the postnatal surgery group, shunts were placed in 79.4%, 86%, and 87.5%, respectively.
The researchers concluded that fetuses with ventricles smaller than 10 mm are the ideal candidates for fetal surgery, while there appears to be no benefit, in relation to shunting, for fetuses with ventricles ≥15 mm. Cases in between should be evaluated carefully before deciding whether to refer them for fetal surgery, the authors concluded.
Tulipan N, Wellons JC 3rd, Thom EA, Gupta N, Sutton LN, Burrows PK, Farmer D,
Walsh W, Johnson MP, Rand L, Tolivaisa S, D'alton ME, Adzick NS; for the MOMS
Investigators. Prenatal surgery for myelomeningocele and the need for
cerebrospinal fluid shunt placement. J Neurosurg Pediatr. 2015 Sep 15:1-8. [Epub
ahead of print]
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