Fetal cisterna magna septa: sonographic feature and its clinical significance / 中华超声影像学杂志

ABSTRACT

Objective To establish normative data for the fetal cisterna magna septa (CMS) at various gestational age,and to evaluate its clinical significance.Methods A total of consecutive fetal between 14 and 40 gestational week(GW) were included in this prospective study.The length and width of CMS were measured by two-dimensional ultrasonography.Regression analysis was used to study the relationship between the width and length of the fetal cisterna magna septa and gestational age.Twenty-five case of fetuses with the absence of CMS and 12 case of fetuses with the enlargement of CMS were retrospectively analyzed in the past six years in our hospital.Results ①The fetal CMS length and width increased gradually between 14 and 22 GW,then plateaued between 23 GW and 36 GW,and decreased after 37 GW.This ultrasonographic pattern was in agreement with normal development of rhombencephalon.②The absence of CMS in the fetuses were common in Dandy-Walker syndrome,holoprosencephaly,severe hydrocephalus,neural tube defects,rhombencephalon synapsis and Arnold-Chiari malformation.The enlargement of CMS in the fetuses may be shown in physiologic enlargement of posterior fossa.ConclusionsCMS is a potential new marker for normal development of rhombencephalon.The enlargement and absence of CMS are related to various malformations of central neural system,especially in the abnormalities of posterior fossa.