Mild fetal cerebral ventriculomegaly: prevalence, characteristics, and utility of ancillary testing in cases presenting to a tertiary referral center

Follow-up outcome analysis of 324 cases of early-onset and late-onset mild fetal ventriculomegaly: a retrospective cohort study

BACKGROUND

Mild fetal ventriculomegaly (VM) is a nonspecific finding common to several pathologies with varying prognosis and is, therefore, a challenge in fetal consultation. We aimed to perform a constant, detailed analysis of prenatal findings and postnatal outcomes in fetuses with early-onset and late-onset mild ventriculomegaly, and provide a new evidence basis and new perspective for prenatal counseling.

METHODS

This is a retrospective cohort study of women with a diagnosis of mild fetal VM between January 2018 and October 2020. The population was divided into two groups according to the gestational ages (GAs) at initial diagnosis: the early-onset group (diagnosed at/before 24+6 weeks) and the late-onset group (diagnosed after 24+6 weeks). Clinical data and pregnancy outcomes were obtained from hospital records. The children's neurodevelopment status was assessed using the Ages and Stages Questionnaire, Third Edition (ASQ-3) and telephone interviews.

RESULTS

Our study cohort comprised 324 fetuses, out of which 94 (29%) were classified as early-onset group and 230 (71%) late-onset group. Early-onset group was more likely to have concurrent additional abnormalities, whereas in the late-onset group, isolated enlargement was more common (P = 0.01). Unilateral enlargement was more common in the late-onset group (P = 0.05), and symmetrical enlargement in the early-onset group (P < 0.01). In addition, early-onset mild VM cases were more likely to have intrauterine progression (P = 0.03), and many had a higher proportion of complex multisystem abnormalities. Compared with the late-onset group, the early-onset group was more often associated with congenital brain structure malformations. Approximately 11% of fetuses with mild VM had postnatal neurodevelopmental delay/disorders, and the risk was higher in the early-onset group (19.4% vs. 7.4%). Regression analysis showed that the GA at first diagnosis, non-isolated, and intrauterine progression significantly correlated with neurodevelopmental abnormalities.

CONCLUSIONS

Early-onset and late-onset mild VM had significantly different ultrasound features and outcomes. Early-onset mild VM may have more complex potential abnormalities and are more likely to predict poor prognosis than the late-onset.

A de novo heterozygous POU3F3 genotype for the p.(Q214*) variant in a fetus with transient isolated bilateral mild ventriculomegaly: a case report and review of the literature

The prenatal prevalence of isolated ventriculomegaly is 0.039%-0.087%. Most isolated mild ventriculomegaly (MV) fetuses (>90%) have a favorable prognosis. However, 5.6% to 7.9% of fetuses with isolated MV have adverse neurodevelopmental outcomes. In this study, we reported the first case of prenatal Snijders Blok-Fisher syndrome (OMIM: #618604) caused by a truncating variant of POU3F3 (OMIM: *602480) in a fetus with transient isolated bilateral MV. The results of karyotype analysis, chromosomal microarray analysis, and TORCH infection evaluation for the fetus were all negative. However, a de novo likely pathogenic nonsense variant of NM_006236.3 (POU3F3): c.640C > T [rs1254251078] p.(Q214*) was identified by whole-exome sequencing (WES). Despite sufficient genetic counseling, the mother refused to undertake further brain magnetic resonance imaging (MRI) and decided to keep the fetus. She gave birth to a male infant through a full-term vaginal delivery. With a long-term follow-up, the infant unfortunately gradually presented with delayed motor development. The postnatal brain MRI of the proband showed dysplasia of the corpus callosum and ventriculomegaly. Considering the high probability of misdiagnosis for such cases, we further summarized the prenatal phenotypes from 19 reported patients with variants in POU3F3. The results revealed that 14 patients displayed a normal prenatal ultrasonographic manifestation, while only approximately 26.32% of fetuses showed MV or cysts without structural deformity. Thus our findings expand the variant spectrum of POU3F3 and suggest the importance of undertaking WES and brain MRI when the fetus has isolated bilateral MV.

Comprehensive quantitative analyses of fetal magnetic resonance imaging in isolated cerebral ventriculomegaly

Isolated cerebral ventriculomegaly (IVM) is the most common prenatally diagnosed brain anomaly occurs in 0.2-1 % of pregnancies. However, knowledge of fetal brain development in IVM is limited. There is no prenatal predictor for IVM to estimate individual risk of neurodevelopmental disability occurs in 10 % of children. To characterize brain development in fetuses with IVM and delineate their individual neuroanatomical variances, we performed comprehensive post-acquisition quantitative analysis of fetal magnetic resonance imaging (MRI). In volumetric analysis, brain MRI of fetuses with IVM (n = 20, 27.0 ± 4.6 weeks of gestation, mean ± SD) had revealed significantly increased volume in the whole brain, cortical plate, subcortical parenchyma, and cerebrum compared to the typically developing fetuses (controls, n = 28, 26.3 ± 5.0). In the cerebral sulcal developmental pattern analysis, fetuses with IVM had altered sulcal positional (both hemispheres) development and combined features of sulcal positional, depth, basin area, in both hemispheres compared to the controls. When comparing distribution of similarity index of individual fetuses, IVM group had shifted toward to lower values compared to the control. About 30 % of fetuses with IVM had no overlap with the distribution of control fetuses. This proof-of-concept study shows that quantitative analysis of fetal MRI can detect emerging subtle neuroanatomical abnormalities in fetuses with IVM and their individual variations.

A myriad of posterior fossa cysts: A single center experience

Antenatal posterior fossa cystic lesions are intimidating due to overlapping imaging features of benign and severe malformations. Sonographic assessment of the posterior fossa with good resolution median sagittal and axial views, either primary or secondarily reconstructed, plays the lead role in antenatal evaluation, further enhanced when sequential assessments are added. We present 10 cases of fetal posterior fossa cystic lesions diagnosed in the first and second trimesters that were sequentially analyzed and followed up till delivery or termination. The ultrasound imaging appearance, evolution, and morphometry have been presented in this article.

Assessment of foetal ventriculomegaly from prenatal to early postnatal period: a single-centre retrospective cohort study

The aim of this study was to evaluate the early neonatal outcomes of cases with foetal ventriculomegaly (VM) and to investigate the aetiological and prognostic factors according to the degree of VM in a single tertiary referring centre. The medical records of 87 foetuses diagnosed with VM (≥10 mm) within 6 years were evaluated. Postnatal evaluation and early neonatal prognosis were determined in 39 cases divided into two groups as mild (10-15 mm, 30 cases) and severe (>15 mm, 9 cases) according to the ventricular size. The mean gestational age at which foetal VM was detected was 22 + 3 weeks. In terms of severity, severe cases of VM were more frequent in terminated pregnancies. There was no difference in gestational age, birth weight, fifth minute Apgar scores, or cord blood gases between mild and severe cases at delivery. Isolated VM was detected in 63% of mild and 22% of severe cases. In severe cases, the need for intensive care and surgery was higher than in mild cases. Antenatal VM regressed in 50% of mild cases and 22% of severe cases. Increasing knowledge about neonatal prognosis, the factors involved in aetiology, and the degree of VM will guide the management of foetal VM.IMPACT STATEMENTWhat is already known in this subject? Some cases of foetal VM resolve spontaneously, and postnatal ultrasonography can detect normal ventricle sizes. While 74.6% of isolated VM cases show spontaneous regression, this rate is 52.1% in nonisolated cases. The gestational week at the time of diagnosis, the degree and cause of VM, intrauterine progression and the presence of any genetic, infectious, cerebral, or extracerebral disorders all influence the prognosis.What do the results of this study add? Antenatal VM regressed in 50% of mild cases and 22% of severe cases. In severe cases, the need for intensive care and surgery was higher than in mild cases. The higher frequency of accompanying cerebral findings in severe cases was striking.What are the implications of these findings for clinical practice and/or further research? The current study revealed that isolated VM with ventricular diameter less than 15 mm, after excluding out chromosomal abnormalities and prenatal infections, and no prior history of VM, has a favourable neonatal prognosis in terms of mortality and morbidity. In cases of foetal VM, increased knowledge of neonatal prognosis will guide pregnancy care and postnatal follow-up planning. Prospective multicentre studies on the neonatal period are required to bridge the gap between foetal VM and long-term consequences.

Central nervous system biometry in fetuses with and without congenital heart diseases

OBJECTIVE

To compare the fetal brain structures assessed in routine sonographic scans during the second and third trimesters in fetuses with and without congenital heart disease (CHD).

METHODS

This is a retrospective cross-sectional single-center study. We measured the head circumference (HC), the transversal diameter of the cerebellum (TCD) and the sizes of the cisterna magna (CM), the cavum septi pellucidi (CSP) and the posterior ventricles (PV) between 20 and 41 weeks of gestation. We compared 160 fetuses with CHD (case group) to 160 fetuses of normal pregnancies (control group). Every patient was matched with a control, considering the gestational age at which the ultrasound was performed. We divided the CHD group into 3 subgroups: retrograde flow in the aortic arch (group 1), right heart anomaly with the antegrade flow in the aortic arch (group 2) and other CHDs with the antegrade flow in the aortic arch (group 3).

RESULTS

The mean width of the PV was larger in fetuses of groups 1 and 3 in comparison to the control group (P < 0.001, P = 0.022; respectively). We found that the APGAR score at 5 min (P < 0.001, P < 0.001; respectively) and gestational age at delivery (P = 0.006, P = 0.001; respectively) were inferior in groups 1 and 3 compared to controls.

CONCLUSIONS

Central nervous system biometry is altered in fetuses with CHD. PV is enlarged in CHD fetuses especially with decreased oxygen levels in the aortic arch.

Cyto/myeloarchitecture of cortical gray matter and superficial white matter in early neurodevelopment: multimodal MRI study in preterm neonates

The cerebral cortex undergoes rapid microstructural changes throughout the third trimester. Recently, there has been growing interest on imaging features that represent cyto/myeloarchitecture underlying intracortical myelination, cortical gray matter (GM), and its adjacent superficial whitematter (sWM). Using 92 magnetic resonance imaging scans from 78 preterm neonates, the current study used combined T1-weighted/T2-weighted (T1w/T2w) intensity ratio and diffusion tensor imaging (DTI) measurements, including fractional anisotropy (FA) and mean diffusivity (MD), to characterize the developing cyto/myeloarchitectural architecture. DTI metrics showed a linear trajectory: FA decreased in GM but increased in sWM with time; and MD decreased in both GM and sWM. Conversely, T1w/T2w measurements showed a distinctive parabolic trajectory, revealing additional cyto/myeloarchitectural signature inferred. Furthermore, the spatiotemporal courses were regionally heterogeneous: central, ventral, and temporal regions of GM and sWM exhibited faster T1w/T2w changes; anterior sWM areas exhibited faster FA increases; and central and cingulate areas in GM and sWM exhibited faster MD decreases. These results may explain cyto/myeloarchitectural processes, including dendritic arborization, synaptogenesis, glial proliferation, and radial glial cell organization and apoptosis. Finally, T1w/T2w values were significantly associated with 1-year language and cognitive outcome scores, while MD significantly decreased with intraventricular hemorrhage.

Role of prenatal magnetic resonance imaging in fetuses with isolated mild or moderate ventriculomegaly in the era of neurosonography: international multicenter study

OBJECTIVES

To assess the role of fetal magnetic resonance imaging (MRI) in detecting associated anomalies in fetuses presenting with mild or moderate isolated ventriculomegaly (VM) undergoing multiplanar ultrasound evaluation of the fetal brain.

METHODS

This was a multicenter, retrospective, cohort study involving 15 referral fetal medicine centers in Italy, the UK and Spain. Inclusion criteria were fetuses affected by isolated mild (ventricular atrial diameter, 10.0-11.9 mm) or moderate (ventricular atrial diameter, 12.0-14.9 mm) VM on ultrasound, defined as VM with normal karyotype and no other additional central nervous system (CNS) or extra-CNS anomalies on ultrasound, undergoing detailed assessment of the fetal brain using a multiplanar approach as suggested by the International Society of Ultrasound in Obstetrics and Gynecology guidelines for the fetal neurosonogram, followed by fetal MRI. The primary outcome of the study was to report the incidence of additional CNS anomalies detected exclusively on prenatal MRI and missed on ultrasound, while the secondary aim was to estimate the incidence of additional anomalies detected exclusively after birth and missed on prenatal imaging (ultrasound and MRI). Subgroup analysis according to gestational age at MRI (< 24 vs ≥ 24 weeks), laterality of VM (unilateral vs bilateral) and severity of dilatation (mild vs moderate VM) were also performed.

RESULTS

Five hundred and fifty-six fetuses with a prenatal diagnosis of isolated mild or moderate VM on ultrasound were included in the analysis. Additional structural anomalies were detected on prenatal MRI and missed on ultrasound in 5.4% (95% CI, 3.8-7.6%) of cases. When considering the type of anomaly, supratentorial intracranial hemorrhage was detected on MRI in 26.7% of fetuses, while polymicrogyria and lissencephaly were detected in 20.0% and 13.3% of cases, respectively. Hypoplasia of the corpus callosum was detected on MRI in 6.7% of cases, while dysgenesis was detected in 3.3%. Fetuses with an associated anomaly detected only on MRI were more likely to have moderate than mild VM (60.0% vs 17.7%; P < 0.001), while there was no significant difference in the proportion of cases with bilateral VM between the two groups (P = 0.2). Logistic regression analysis showed that lower maternal body mass index (adjusted odds ratio (aOR), 0.85 (95% CI, 0.7-0.99); P = 0.030), the presence of moderate VM (aOR, 5.8 (95% CI, 2.6-13.4); P < 0.001) and gestational age at MRI ≥ 24 weeks (aOR, 4.1 (95% CI, 1.1-15.3); P = 0.038) were associated independently with the probability of detecting an associated anomaly on MRI. Associated anomalies were detected exclusively at birth and missed on prenatal imaging in 3.8% of cases.

CONCLUSIONS

The incidence of an associated fetal anomaly missed on ultrasound and detected only on fetal MRI in fetuses with isolated mild or moderate VM undergoing neurosonography is lower than that reported previously. The large majority of these anomalies are difficult to detect on ultrasound. The findings from this study support the practice of MRI assessment in every fetus with a prenatal diagnosis of VM, although parents can be reassured of the low risk of an associated anomaly when VM is isolated on neurosonography. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Disruption and Compensation of Sulcation-based Covariance Networks in Neonatal Brain Growth after Perinatal Injury

Perinatal brain injuries in preterm neonates are associated with alterations in structural neurodevelopment, leading to impaired cognition, motor coordination, and behavior. However, it remains unknown how such injuries affect postnatal cortical folding and structural covariance networks, which indicate functional parcellation and reciprocal brain connectivity. Studying 229 magnetic resonance scans from 158 preterm neonates (n = 158, mean age = 28.2), we found that severe injuries including intraventricular hemorrhage, periventricular leukomalacia, and ventriculomegaly lead to significantly reduced cortical folding and increased covariance (hyper-covariance) in only the early (<31 weeks) but not middle (31-35 weeks) or late stage (>35 weeks) of the third trimester. The aberrant hyper-covariance may drive acceleration of cortical folding as a compensatory mechanism to "catch-up" with normal development. By 40 weeks, preterm neonates with/without severe brain injuries exhibited no difference in cortical folding and covariance compared with healthy term neonates. However, graph theory-based analysis showed that even after recovery, severely injured brains exhibit a more segregated, less integrated, and overall inefficient network system with reduced integration strength in the dorsal attention, frontoparietal, limbic, and visual network systems. Ultimately, severe perinatal injuries cause network-level deviations that persist until the late stage of the third trimester and may contribute to neurofunctional impairment.

Ultrasound Measurements of Frontal Horns and the Cavum Septi Pellucidi in Healthy Fetuses in the Second and Third Trimesters of Pregnancy

OBJECTIVES

To assess the visualization rate and size of the frontal horns (FHs) and cavum septi pellucidi (CSP) in healthy fetuses throughout pregnancy.

METHODS

After Institutional Review Board approval, 522 consecutive uncomplicated singleton pregnancies between 15 and 39 gestational weeks were enrolled in the study. Ultrasound measurements of the anterior horn width (AHW), center from the horn distance (CFHD), distance from the FHs to the CSP, and CSP width were retrospectively performed using axial transventricular or transcerebellar planes. Available maternal body mass indices were recorded.

RESULTS

At least 1 FH was seen in 78% of the cases. The mean AHW decreased over the second trimester and plateaued in the third trimester. The CFHD plateaued in the second trimester and increased in the third trimester. Downside FHs were generally larger than upside FHs. More FHs were measured in transventricular (69%) than transcerebellar (31%) planes. Frontal horns were seen with high, low, and no confidence in 57%, 21%, and 22% of cases, respectively. No-confidence rates were 17% in the second trimester and 42% in the third trimester. The CSP was not visualized in 4% of cases; 15 of 19 cases of a nonvisualized CSP were scanned between 18 and 37 weeks. Mean body mass indices ± SDs were 27.6 ± 6.7 kg/m² for the patients in cases of a visualized CSP and 32.4 ± 9.1 kg/m² for the patients in cases of a nonvisualized CSP.

CONCLUSIONS

Normative data for the fetal FH and CSP width were established. Frontal horns are more frequently seen on transventricular views and are difficult to confidently assess in the late third trimester. This study challenges previously reported data that the CSP is seen in 100% of cases from 18 to 37 weeks.

Role of magnetic resonance imaging in fetuses with mild or moderate ventriculomegaly in the era of fetal neurosonography: systematic review and meta-analysis

OBJECTIVES

To report the rate of additional central nervous system (CNS) anomalies detected exclusively on prenatal magnetic resonance imaging (MRI) in fetuses diagnosed with isolated mild or moderate ventriculomegaly (VM) on ultrasound, according to the type of ultrasound protocol adopted (dedicated neurosonography vs standard assessment of the fetal brain), and to explore whether the diagnostic performance of fetal MRI in detecting such anomalies is affected by gestational age at examination and laterality and degree of ventricular dilatation.

METHODS

MEDLINE, EMBASE, CINAHL and Clinicaltrials.gov were searched for studies reporting on the prenatal MRI assessment of fetuses diagnosed with isolated mild or moderate VM (ventricular dilatation of 10-15 mm) on ultrasound. Additional anomalies detected only on MRI were classified as callosal, septal, posterior fossa, white matter, intraventricular hemorrhage, cortical, periventricular heterotopia, periventricular cysts or complex malformations. The rate of additional anomalies was compared between fetuses diagnosed on dedicated neurosonography, defined as a detailed assessment of the fetal brain, according to the International Society of Ultrasound in Obstetrics and Gynecology guidelines, and those diagnosed on standard fetal brain assessment. The rate of additional CNS anomalies missed on prenatal MRI and detected only at birth was calculated and compared between fetuses that had early (at or before 24 weeks' gestation) and those that had late (after 24 weeks) MRI. Subanalysis was performed according to the laterality (uni- vs bilateral) and degree (mild vs moderate, defined as ventricular dilatation of 10-12 and 13-15 mm, respectively) of ventricular dilatation. Whether MRI assessment led to a significant change in prenatal management was explored. Random-effects meta-analysis of proportions was used.

RESULTS

Sixteen studies (1159 fetuses) were included in the systematic review. Overall, MRI detected an anomaly not identified on ultrasound in 10.0% (95% CI, 6.2-14.5%) of fetuses. However, when stratifying the analysis according to the type of ultrasound assessment, the rate of associated anomalies detected only on MRI was 5.0% (95% CI, 3.0-7.0%) when dedicated neurosonography was performed compared with 16.8% (95% CI, 8.3-27.6%) in cases that underwent a standard assessment of the fetal brain in the axial plane. The overall rate of an additional anomaly detected only at birth and missed on prenatal MRI was 0.9% (95% CI, 0.04-1.5%) (I² , 0%). There was no difference in the rate of an associated anomaly detected only after birth when fetal MRI was carried out before, compared with after, 24 weeks of gestation (P = 0.265). The risk of detecting an associated CNS abnormality on MRI was higher in fetuses with moderate than in those with mild VM (odds ratio, 8.1 (95% CI, 2.3-29.0); P = 0.001), while there was no difference in those presenting with bilateral, compared with unilateral, dilatation (P = 0.333). Finally, a significant change in perinatal management, mainly termination of pregnancy owing to parental request, following MRI detection of an associated anomaly, was observed in 2.9% (95% CI, 0.01-9.8%) of fetuses undergoing dedicated neurosonography compared with 5.1% (95% CI, 3.2-7.5%) of those having standard assessment.

CONCLUSIONS

In fetuses undergoing dedicated neurosonography, the rate of a CNS anomaly detected exclusively on MRI is lower than that reported previously. Early MRI has an excellent diagnostic performance in identifying additional CNS anomalies, although the findings from this review suggest that MRI performed in the third trimester may be associated with a better detection rate for some types of anomaly, such as cortical, white matter and intracranial hemorrhagic anomalies. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

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

Developmental brain abnormalities are complex and can be difficult to diagnose by prenatal imaging because of the ongoing growth and development of the brain throughout pregnancy and the limitations of ultrasound, often requiring fetal magnetic resonance imaging as an additional tool. As for all major structural congenital anomalies, amniocentesis with chromosomal microarray and a karyotype is the first-line recommended test for the genetic work-up of prenatally diagnosed central nervous system (CNS) abnormalities. Many CNS defects, especially neuronal migration defects affecting the cerebral and cerebellar cortex, are caused by single-gene mutations in a large number of different genes. Early data suggest that prenatal diagnostic exome sequencing for fetal CNS defects will have a high diagnostic yield, but interpretation of sequencing results can be complex. Yet a genetic diagnosis is important for prognosis prediction and recurrence risk counseling. The evaluation and management of such patients is best done in a multidisciplinary team approach. Here, we review general principles of the genetic work-up for fetuses with CNS defects and review categories of genetic causes of prenatally diagnosed CNS phenotypes.

Current Controversies in Prenatal Diagnosis 1: Should MRI be performed on all fetuses with mild ventriculomegaly?

A ventricular diameter of 10 mm correlates with more than two standard deviations of the normal and hence is qualified as ventriculomegaly. The relevance of this is dependent on whether there are associated infectious, genetic, or structural problems. The chance for neurodevelopmental delay in isolated ventriculomegaly less than 15 mm is 7.9% (4.7-11.1), and less if it is unilateral. It can be further divided in mild (10-12) or moderate (13-15), though this is not widely accepted. As part of the workup, structural assessment today may include ultrasound or magnetic resonance imaging, or both. Discussants agreed that the diagnostic performance of both methods is as good as the expertise with which the images are acquired and interpreted. Discussants agreed that when the initial neurosonogram is normal, the likelihood of finding significant findings on MRI is low. Nevertheless, some anomalies may only be picked up or better worked out by fetal MRI. In utero follow-up is advocated, as progression may indicate a poorer outcome, and some conditions are only obvious late in pregnancy. Most benefit for future patients is expected from appropriate training in prenatal neuroimaging.

Fetal brain development in diabetic pregnancies and normal controls

Objective:

To compare the fetal brain structures assessed in routine sonographic scans during the second and third trimesters in diabetic and normal pregnancies.

Methods:

In this retrospective study, we measured the head circumference (HC), the transversal diameter of the cerebellum (TCD) and the sizes of the cisterna magna (CM), the cavum septi pellucidi (CSP) and the lateral ventricles (LV) in stored sonographic scans between 20 and 41 weeks of gestation. We compared 231 fetuses of diabetic mothers (diabetic group) to 231 fetuses of normal pregnancies (control group) matched by gestational age. The diabetic group was divided into three subgroups: pre-existing maternal diabetes, diet-controlled gestational diabetes and insulin-dependent gestational diabetes.

Results:

The mean widths of the CSP and LV were larger in fetuses of diabetic mothers in comparison with the controls (P<0.001, P<0.001; respectively). The sizes of HC, CM and TCD were similar in both groups. These results were consistent across the three subgroups.

Conclusions:

Diabetes is associated with altered fetal brain development. We would like to introduce the increased widths of CSP and LV as potential markers for gestational diabetes.