Increased Sylvian fissure angle as early sonographic sign of malformation of cortical development

Abstract

Objective To evaluate Sylvian fissure development by assessing Sylvian fissure angles in fetuses with malformation of cortical development (MCD). Methods This was a retrospective study of 22 fetuses with MCD. Cases with a stored three‐dimensional (3D) brain volume acquired at 18 + 0 to 30 + 6 weeks of gestation at an ultrasound‐based research clinic between January 2010 and December 2017 were identified through a database. Of the 22 fetuses, seven had an extracranial abnormality, such as cardiac, renal, gastrointestinal and/or digital anomalies, and five had a minor abnormality such as micrognathia, low‐set ears and/or single umbilical artery. To confirm the final clinical diagnosis of brain abnormality, postmortem histological findings or prenatal or postnatal magnetic resonance images were used. For measurement of Sylvian fissure angle, an anterior coronal plane of the fetal brain on transvaginal 3D volume multiplanar imaging was visualized as a single image from the three orthogonal views. The right and left Sylvian fissure angles were measured between a horizontal reference line (0°) and a line drawn along the upper side of the respective Sylvian fissure. The Sylvian fissure angle on both sides was plotted on the graphs of the reference ranges for gestational age in weeks. Results In 21 (95.5%; 95% CI, 86.8–100.0%) of 22 fetuses with MCD, the Sylvian fissure angle on one or both sides was larger than the 90th percentile of the normal reference. There was one case with apparent focal MCD in the parietal lobe, but the Sylvian fissure angles were normal. A case with apparent unilateral cortical dysplasia and one with apparent unilateral schizencephaly had conspicuous discrepancies between the left and right Sylvian fissure angles. Abnormal genetic test results were obtained in six cases, including four cases with a mutation in a single gene. Conclusions This study has shown that the Sylvian fissures, as defined by the Sylvian fissure angle, have delayed development in most MCD cases prior to the diagnosis of the condition. The Sylvian fissure angle may potentially be a strong indicator for the subsequent development of cortical malformation, before the time point at which the gyri and sulci become obvious on the fetal brain surface. Further research is required to validate these findings. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Validation of a semiautomated volumetric approach for fetal neurosonography using 5DCNS+ in clinical data from > 1100 consecutive pregnancies

“…Gindes et al demonstrated that the sylvian fissure grows asymmetrically in an anterior-posterior direction rather than laterally or in the inferior-superior direction. Very recently, reference charts of the sylvian fissure angle obtained in strictly coronal views have been published [20], giving early hints towards delayed development seen in most cortical malformations [19]. Our data corroborate and further specify the time pattern of CNS folding because we had 100% visualization of the lateral sulcus and the ongoing process of operculization at 20 completed weeks.…”

“…Accordingly, an accurate grading of the time-dependent cortical folding for other primary fissures such as the parietooccipital fissure, calcarine fissure, and the cingulate sulcus is feasible with obligate visualization from 23 and 24 weeks onward [1,5]. There are also technical issues in the comprehensive assessment of the sylvian fissure in the same cutting plane and a lack of standardization in both plane reconstruction and the quantification of spatial-cerebral relationships [19]. In 2015, two publications reported the reliability of multiplanar 3D ultrasounds for systematic (longitudinal) assessments of cortical differentiation, confirming prior studies [2,6,9,14,15].…”

Prenatally diagnosed developmental abnormalities of the central nervous system and genetic syndromes: A practical review

“…They can be difficult to see on prenatal ultrasound and are best evaluated by MRI, performed in the late second or early third trimester (after 20‐22 wk) . Recent studies have suggested that an abnormal shape and size of the sylvian fissure in early pregnancy can be an early sign of migration abnormalities and indication for further imaging by ultrasound and MRI at a later gestational age . The most common location is in the bilateral perisylvian region, but they can be unilateral and have an anterior‐posterior or posterior‐anterior gradient.…”

Sylvian fossa sonographic measurements in 18 to 23 weeks fetuses with and without cerebral malformations

“…Previous studies have addressed the problem of quantifying sonographically the process of opercularization and formation of the Sylvian fissure. 7,12,14,15,17 The normal values of the distance between the inner calvarium and the insula have been previously published. 15,17 However, we object that this is an indirect measurement of the Sylvian fossa, because it includes the subarachnoid space, which is variable in size and distribution.…”