Prenatal surgery for myelomeningocele: review of the literature and future directions

Open spina bifida or myelomeningocele (MMC) is one of the most common serious congenital malformations. Historically, this condition has been treated with closure of the MMC defect shortly after birth. The goal of postnatal closure is to cover the exposed spinal cord and prevent infection. However, postnatal surgery does not reverse or prevent the neurologic injury seen in MMC, reverse hindbrain herniation, or prevent hydrocephalus. The neurologic defects result from primary incomplete neurulation and secondary chronic prenatal damage to the exposed neural elements through mechanical and chemical trauma. In a hope to reduce the numerous surgical procedures, medical complications, and lifelong disabilities associated with MMC, the proposal of prenatal closure was put forth more than two decades ago. After promising results in animal models and some clinical series, a randomized controlled trial, the Management of Myelomeningocele Study (MOMS), was conducted. The MOMS trial demonstrated that closure during the prenatal period could be performed relatively safely and can result in significant benefit to the child. Specifically, prenatal closure results in improved motor function, reduced hindbrain herniation, and reduced need for a cerebral spinal fluid diversion. Long-term outcomes of the patients in the MOMS trial continues in the MOMS 2 study as these children grow. Additionally, investigations are underway on modifications to the open fetal MMC closure techniques.