Open fetal surgery for neural tube defects

The most common congenital defect of the central nervous system is myelomeningocele (MMC), which results in significant physical limitations for those affected. Neurologic injury associated with MMC begins with abnormal neurulation and is perpetuated by subsequent traumatic and toxic injury sustained in utero. Treatment historically has involved surgical closure of the MMC after birth along with neonatal management of the associated sequelae including cerebrospinal fluid diversion by ventricular shunting. With improvements in prenatal diagnosis, a defined antenatal natural history, and the concept of fetal intervention to arrest or reverse ongoing in utero damage, maternal-fetal surgery for MMC closure developed as a feasible therapy. Animal studies and early human studies investigating in utero MMC closure were promising, leading to Management of Myelomeningocele Study (MOMS trial). This prospective randomized multicenter trial comparing in utero fetal MMC (fMMC) closure to routine postnatal closure demonstrated a decreased need for shunting, reversal of hindbrain herniation, and improved neurologic function in the prenatal repair group, although maternal complications and prematurity were more frequently encountered. Because of the conclusion of the MOMS trial, fMMC closure has become a standard of care option for pregnancies complicated by a prenatal diagnosis of spina bifida. This article will provide background to the scope of MMC, review the MOMS trial data, and highlight the current clinical status of open fMMC closure.