Hindbrain herniation develops in surgically created myelomeningocele but is absent after repair in fetal lambs

Objective: The purpose of our study was to determine whether prenatal repair of myelomeningocele prevents or reverses hindbrain herniation in the sheep model. Study Design: A myelomeningocele was surgically created in fetal sheep. One group was repaired later in utero; the others were delivered without repair. After delivery, lambs were assessed for the presence of hindbrain herniation. Results: In all lambs that had not undergone repair of the myelomeningocele, severe hindbrain herniation developed, whereas the brains of all lambs that had undergone fetal repair were normal. Conclusion: Prenatal repair of myelomeningocele prevents or reverses development of hindbrain herniation in the fetal lamb model. (Am J Obstet Gynecol 2000;183:1119-23.)