ROLE OF ULTRASONOGRAPHY IN EVALUATION OF NORMAL DEVELOPMENTAL PATTERN OF FETAL CEREBRAL SULCI BETWEEN 18 TO 32 WEEKS OF GESTATIONAL AGE

Abstract

Background: CNS development is crucial in all stages of intrauterine life. Ultrasonography gives a better visualization of brain structures and development of various sulci and gyri throughout the gestation. Hence this study is aimed to study the developmental patterns of various sulci and gyri based on their serial appearance on ultrasonography. Aims and Objectives: To evaluate the patterns of appearance of various fetal cerebral sulci using ultrasonography between 18 to 32 weeks gestational age, to depict the chronological order of appearance of these fetal cerebral sulci and to correlate the appearance of various cerebral sulci with the gestational age. Material and Methods: A cross-sectional study was conducted over a period of eighteen months on 241 antenatal mothers with singleton pregnancy between the gestational age of 18 to 32 weeks, who were referred to our department for routine antenatal ultrasonography. All the statutory requirements under PC and PNDT act were followed and form ‘F’ duly completed. Gestational age was established by at least one of the ultrasound scans performed before 13 weeks of gestation. Present gestational age was determined by ultrasound biometry (average of biparietal diameter, head circumference, abdominal circumference and femur length) at time of the study scan and was correlated with the gestational age as per dating scan or scans performed before 13 weeks of gestation. XV Those sulci and fissures which have been reported to appear relatively early on anatomical studies were evaluated, specifically parieto-occipital fissure, calcarine fissure, cingulate sulci, convexity sulci and the insula/sylvian fissure. Comparison of the categorical outcomes were done between study groups using Chi square test. P value < 0.05 was considered statistically significant. Results: A total of 241 fetuses were analyzed in the study. The appearances of parieto-occipital fissure, calcarine fissure and cingulate sulci progressed from a dot pattern to V shaped indentation and finally forming a Y shaped configuration as the gestational age progressed. Parieto-occipital fissure was the first sulci to develop among the sulci studied and was always present at 18 weeks as a V shaped indentation, Calcarine fissure was the next fissure to appear and was present as a dot pattern at 18 weeks. All fissures except cingulate sulci had appeared by gestational age of 20 weeks. Appearance of calcarine sulci was significant by around 20-21 weeks of gestation. Sylvian fissure initially appeared as smooth surface, later underwent operculization to form obtuse and finally acute angulations with the adjacent temporal lobe. Convexity sulci were seen as indentations on lateral surface of brain and appears later in the gestational age by 25-26 weeks. Conclusions: The results of the study showed the developmental patterns of various fetal cerebral sulci, chronological order of their appearance and their patterns at various gestational age.