Myelomeningocele (MMC) is a devastating congenital defect that results in exposure of the developing spinal cord to the intrauterine environment leading to progressive damage from contact with the uterine wall and toxic effects of the amniotic fluid. This leads to irreversible loss of bowel and bladder control as well as partial or complete paralysis of the lower limbs. The open defect also alters normal CSF hydrodynamics resulting in hindbrain herniation and obstruction of CSF flow leading to progressive hydrocephalus. In a fetal sheep model, prenatal closure of the spinal defect resulted in near normal motor function, continence of stool and urine, and intact sensation to the lower extremities. Encouraged by these studies, protocols were recently developed for prenatal repair in humans. Present selection criteria for fetal repair include normal karyotype, absence of other significant anomalies (based on echocardiography, ultrasound, and ultrafast fetal MRI studies), defect at or above the S-1 level associated with hindbrain herniation and ventriculomegaly of less than 17 mm, and gestational age of less than 26 weeks. Delivery is planned for 36–37 weeks’ gestation by cesarean section following confirmation of fetal lung maturity by amniocentesis. Outcome data to date suggest reversal of hindbrain herniation in all cases, reduction in ventriculoperitoneal shunt rates to 40–45%, and better than predicted neurofunctional outcomes in over half the infants with thoracic or lumbar level lesions. These promising results have led to an NIH-sponsored, prospective, randomized trial comparing prenatal repair to traditional management by elective near-term cesarean section and post-natal MMC closure. Myelomeningocele (MMC) is a devastating congenital defect that results in exposure of the developing spinal cord to the intrauterine environment leading to progressive damage from contact with the uterine wall and toxic effects of the amniotic fluid. This leads to irreversible loss of bowel and bladder control as well as partial or complete paralysis of the lower limbs. The open defect also alters normal CSF hydrodynamics resulting in hindbrain herniation and obstruction of CSF flow leading to progressive hydrocephalus. In a fetal sheep model, prenatal closure of the spinal defect resulted in near normal motor function, continence of stool and urine, and intact sensation to the lower extremities. Encouraged by these studies, protocols were recently developed for prenatal repair in humans. Present selection criteria for fetal repair include normal karyotype, absence of other significant anomalies (based on echocardiography, ultrasound, and ultrafast fetal MRI studies), defect at or above the S-1 level associated with hindbrain herniation and ventriculomegaly of less than 17 mm, and gestational age of less than 26 weeks. Delivery is planned for 36–37 weeks’ gestation by cesarean section following confirmation of fetal lung maturity by amniocentesis. Outcome data to date suggest reversal of hindbrain herniation in all cases, reduction in ventriculoperitoneal shunt rates to 40–45%, and better than predicted neurofunctional outcomes in over half the infants with thoracic or lumbar level lesions. These promising results have led to an NIH-sponsored, prospective, randomized trial comparing prenatal repair to traditional management by elective near-term cesarean section and post-natal MMC closure.
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