J Neurosurg Pediatr. 2026 May 15:1-9. doi: 10.3171/2025.12.PEDS25317. Online ahead of print.
ABSTRACT
OBJECTIVE: Fetal myelomeningocele repair (FMMR) has shown significant promise in decreasing the incidence of myelomeningocele (MMC)-associated hydrocephalus. In this study, the authors report on the reversal of hindbrain herniation via FMMR. They also describe biometric changes in third ventricle anatomy, which influences the outcome of endoscopic third ventriculostomy and choroid plexus cauterization (ETV/CPC).
METHODS: At the Arnold Palmer Hospital for Children and Winnie Palmer Hospital for Women & Babies, the maternal and fetal inclusion and exclusion criteria developed by the Management of Myelomeningocele Study (MOMS) were applied to determine eligibility for prenatal MMC repair. Patient charts, prenatal fetal MRI, ultrasonography studies, and postnatal brain MRI for the first 50 FMMRs performed between 2019 and 2024 were retrospectively reviewed for this study. Ventricle size was measured prior to fetal surgery, as was the clivus-supraocciput angle (CSO) on fetal and postnatal images. Neonates were stratified into hydrocephalic and nonhydrocephalic groups for comparative analysis. The hydrocephalic group included patients who had undergone ETV/CPC or insertion of a ventriculoperitoneal shunt (VPS).
RESULTS: A total of 50 women underwent FMMR. One woman did not consent to inclusion in the study, 8 patients remained in utero at the time of analysis, and 3 patients died. Of the 38 patients included in the analysis, 21 (55%) underwent treatment for their symptomatic hydrocephalus; 4 received a VPS, and 17 underwent ETV/CPC. Four ETV/CPC cases did not respond to the treatment and were scheduled for VPS insertion, resulting in an overall ETV/CPC success rate of 70.6% (12/17) in the study. A statistically significant difference in the mean prenatal ventricle size was observed between the nonhydrocephalic (9.61 mm) and hydrocephalic (12.1 mm, p = 0.023) groups. Additionally, a significant difference in the CSO angle in the first month after birth was noted between the groups (67.2° vs 76.7°, p = 0.01).
CONCLUSIONS: There is strong evidence that FMMR decreases MMC-related hydrocephalus by reversing hindbrain herniation and altering the developmental anatomy of the third ventricle. This makes ETV/CPC a safe alternative to CSF shunting because of the newly altered anatomy of the third ventricle and posterior fossa. Larger studies are recommended to further evaluate fetal brain development after FMMR.
PMID:42139738 | DOI:10.3171/2025.12.PEDS25317
