No abstract

Objectives: Myelomeningocele is the most prevalent non-lethal central nervous system malformation and is associated to the Arnold Chiari II malformation. MOMS showed, that prenatal repair of myelomeningocele reduces the postnatal need for placement of a cerebroespinal fluid shunt, hydrocephalus, posterior fossa herniation and perinatal morbidity and mortality. The objective of this study is to describe the intrauterine imaging monitoring of posterior fossa, A. Chiari II signs after prenatal repair. Methods: Casuistry of Chilean public hospital in Valparaíso, Hospital Carlos Van Buren, is exposed. The program of prenatal myelomeningocele surgery began on December 2014 at this centre. Until the date we have performed nine ( 9) of these intervention. The inclusion criteria were singleton pregnancy, gestational age under 27 weeks and diagnosis of neural tube defect with Myelomeningocele. Post-surgical follow up was performed through Neurosonography and Fetal MRI. Results: The average gestational age at diagnosis was 22 weeks. All of these 9 fetus presented A. Chiari malformation. The prenatal surgery was carried out between week 24+5 and 27+0. There was one neonatal death at 28 weeks for chorioamnionitis. Ninth case is a still ongoing pregnancy.Mean gestational age at delivery was 32.7 weeks including the adverse event, (Rank from 28 to 37 weeks). The imaging post-surgical follow up showed objective improvement of A. Chiari in 8 survival fetus: appearance of cisterna magna, reversion of abnormal curvature of cerebellar hemispheres, decreased of ventriculomegaly, recovery of IV ventricle and less cerebellar herniation by foramen magnum is observed. Conclusions: This series of cases demonstrates improvement in the post surgical ultrasound and MRI signs of defects of the posterior fosa including A. Chiari II. These findings show a break in the natural history of the disease.