Improvement in hindbrain herniation demonstrated by serial fetal magnetic resonance imaging following fetal surgery for myelomeningocele

Context Hindbrain herniation occurs in a large percentage of children with myelomeningocele and is the leading cause of death in this population. The effect of early fetal closure of myelomeningocele on hindbrain herniation i s unknown. Objective To determine whether early fetal closure of myelomeningocele affe cts hindbrain herniation, Design Case series of patients undergoing fetal myelomeningocele closure wi th serial measurements of hindbrain herniation and a mean follow-up of 182 days, Setting Tertiary care medical center. Participants Ten patients undergoing fetal myelomeningocele closure at 22 t o 25 weeks' gestation between March 1998 and February 1999. Main Outcome Measures Need for shunt placement; degree of hindbrain herniat ion (grades 0-3) found on magnetic resonance imaging (MRI) performed prior to surgery and 3 and 6 weeks after fetal surgery, as well as shortly after birth; gestational age at delivery. Results All initial fetal MRI scans performed at 19 to 24 weeks' gestation showed significant (grade 3) cerebellar herniation and absence of spinal fl uid spaces around the cerebellum Six fetuses were delivered electively at 3 6 weeks' gestation after lung maturity was established. The other 4 were de livered prematurely, at 25, 30, 30, and 31 weeks of gestation, and the 25-w eek gestation neonate died. All 9 surviving neonates showed improvement in the hindbrain hernia at the 3-week postoperative fetal scan (grade 2, n = 4 ; grade 1, n = 5). On the postnatal scan, all patients showed grade 1 hindb rain herniation. Only 1 patient required placement of a ventriculoperitonea l shunt. Conclusion In this series of patients, fetal myelomeningocele closure resul ted in improvement in hindbrain herniation as demonstrated by serial MRI sc ans.