Establishment Of Normal Curve Of Fetal Sylvian Fissure Development And Prenatal Outcome Of Fetuses With Ventriculomegaly Complicated With Sylvian Assure Dysplasia

Background And PurposeFetal congenital developmental abnormalities can occur in any organ system,in which the incidence of congenital dysplasia of nervous system is the highest,about0.5%.Most fetuses with congenital central nervous system dysplasia are difficult to treat and have a poor prognosis after birth,which has been the focus and difficulty of prenatal diagnosis for a long time.Ultrasound is the first choice for examination of fetal central nervous system（CNS）malformations,which can effectively improve the rate of clinical diagnosis.Sylvian fissure（SF）is the earliest,most obvious and broad of all cerebral sulcus gyrus.The depth and morphological changes of lateral fissure reflect the maturity of sulcus gyrus development,and then evaluate the development process of cerebral cortex,which has a relatively constant position and shape.At present,there is no unified and effective clinical parameter to evaluate the development of lateral fissure.The purpose of this study is to find the law of lateral fissure development with gestational weeks and to establish a normal development curve.The broadening of the lateral ventricle is a variation of the normal anatomical structure.The widening of the lateral ventricle indicates a significant increase in the risk of fetal developmental malformations and chromosomal abnormalities.Current studies have shown that the prognosis of broadened lateral ventricle is mainly related to two factors:first,whether it is complicated with other malformations or genetic syndrome;second,whether the width of lateral ventricle increases with the increase of gestational weeks.The simple enlargement of the lateral ventricle of the fetus has a good prognosis,but how to determine the widening of the lateral ventricle is full of clinical challenges and uncertainty for prenatal consultation.The purpose of this study is to provide a reference basis for the prognostic analysis of lateral ventricular enlargement through the study and analysis of lateral fissure in patients with widened lateral ventricle.The purpose of this study is:first,to establish the normal development curve of fetal lateral fissure in the second and third trimester（22-34 weeks）by measuring the width,depth,area and angle of fetal lateral fissure.Second,to explore whether the broadened lateral ventricle has an effect on the normal development curve of the lateral fissure of the fetus by measuring the development of the lateral fissure of the fetus with mild or moderate enlargement of the lateral ventricle.And third,the results of prenatal diagnosis of fetal lateral ventricular enlargement with lateral fissure dysplasia were analyzed to explore the incidence of fetal chromosomal disease or genetic syndrome.To provide reference for clinicians.MethodsIn this study,150 pregnant women who received routine fetal ultrasound screening in our hospital from January 2021 to July 2022(22-34⁺⁶weeks)were divided into normal group according to the admission criteria.The width of the upper edge of Sylvian fissure（SF）,the maximum depth of Cerebral sulcus depression,depression area and depression angle were taken as dependent variables,gestational weeks as independent variables,and the best fitting model was selected to establish regression equation and 95%normal value reference range.The development of lateral fissure,prenatal diagnosis and pregnancy outcome were analyzed in 47 cases of lateral ventricular enlargement group,and the related factors between lateral ventricular enlargement and lateral fissure development were evaluated.ResultsThe reference ranges of the width of SF upper edge of lateral cerebral fissure,the maximum depth of SF sulcus depression,the area of SF depression and the angle of SF depression with gestational weeks were established.It was found that the width,maximum depth and area of SF superior margin of normal fetuses from 22 to 34⁺⁶weeks of gestation were positively correlated with gestational weeks,while the angle of lateral fissure was negatively correlated with gestational weeks.The regression equations obtained are as follows:SF-L（mm）=-103.3194+6.9976*gestational weeks-0.09515*gestational weeks²,SF-H（mm）=-27.6896+1.9148*gestational weeks-0.02024*gestational weeks²,log（SF-Area（mm2））=0.8516+0.04455*gestational weeks,and SF-Ang（°）^0.07=2.3352-0.05715*gestational weeks+0.0007326*gestational weeks ².It was found that simple broadening of the lateral ventricle had no effect on the development of the lateral fissure.The detection rate of chromosome abnormality in the broadened lateral ventricle was 8.6%（3/35）,and the detection rate of chromosome abnormality in the case of broadened lateral ventricle with abnormal development of the lateral fissure was 42.9%（3/7）.ConclusionsThe main results are as follows:First,the reference ranges of width,maximum depth,depression area and angle of lateral fissure of normal fetus at 22-34 weeks of pregnancy were established by establishing regression equation.It provides valuable information for ultrasound to evaluate the development of cerebral sulcus gyrus and prenatal diagnosis of abnormal development of fetal cerebral cortex.Second,through comparative analysis,it is confirmed that the widening of the lateral ventricle of the fetus has no effect on the normal development curve of the lateral fissure of the brain.Third,the detection rate of chromosomal disease or genetic syndrome in fetuses with broadened lateral ventricles and dysplasia of lateral fissure was 42.9%,including 2cases of microdeletion syndrome and 1 case of genetic syndrome caused by gene mutation.