Distal lateral ventricular atrium: reevaluation of normal range

Role of prenatal magnetic resonance imaging in fetuses with isolated severe ventriculomegaly at neurosonography: A multicenter study

OBJECTIVE

The aim of this study was to report the rate of additional anomalies detected exclusively at prenatal magnetic resonance imaging (MRI) in fetuses with isolated severe ventriculomegaly undergoing neurosonography.

METHOD

Multicenter, retrospective, cohort study involving 20 referral fetal medicine centers in Italy, United Kingdom, Spain and Denmark. Inclusion criteria were fetuses affected by isolated severe ventriculomegaly (≥15 mm), defined as ventriculomegaly with normal karyotype and no other additional central nervous system (CNS) and extra-CNS anomalies on ultrasound. In all cases, a multiplanar assessment of fetal brain as suggested by ISUOG guidelines on fetal neurosonography had been performed. The primary outcome was the rate of additional CNS anomalies detected exclusively at fetal MRI within two weeks from neurosonography. Subgroup analyses according to gestational age at MRI (<vs ≥ 24 weeks of gestation) and the laterality of ventriculomegaly (unilateral vs bilateral) were also performed. Univariate and multivariate logistic regression analysis was used to analyze the data.

RESULTS

187 fetuses with a prenatal diagnosis of isolated severe ventriculomegaly on neurosonography were included in the analysis. Additional structural anomalies were detected exclusively at prenatal MRI in 18.1% of cases. When considering the type of anomaly, malformations of cortical development were detected on MRI in 32.4% cases, while midline or acquired (hypoxemic/hemorrhagic) lesions were detected in 26.5% and 14.7% of cases, respectively. There was no difference in the rate of additional anomalies when stratifying the analysis according to either gestational age at MRI or laterality of the lesion. At multivariate logistic regression analysis, the presence of additional anomalies only found at MRI was significantly higher in bilateral compared versus unilateral ventriculomegaly (OR: 4.37, 95% CI 1.21-15.76; p = 0.04), while neither maternal body mass index, age, severity of ventricular dilatation, interval between ultrasound and MRI, nor gestational age at MRI were associated with the likelihood of detecting associated anomalies at MRI.

CONCLUSION

The rate of associated anomalies detected exclusively at prenatal MRI in fetuses with isolated severe ventriculomegaly is lower than previously reported, but higher compared to isolated mild and moderate ventriculomegaly. Fetal MRI should be considered as a part of the prenatal assessment of fetuses presenting with isolated severe ventriculomegaly at neurosonography.

The Significance of Fetal Brain Ventricular Asymmetry Without Dilation

OBJECTIVES

Fetal brain non-dilated ventricular asymmetry (NDVA) is a common finding on prenatal ultrasound exams. However, the optimal prenatal management in these cases remains unknown. We aimed to evaluate the benefit of prenatal genetic and magnetic resonance imaging (MRI) exams performed in cases of fetal NDVA detected on ultrasound.

METHODS

A historical cohort study from a tertiary medical center. Singleton pregnancies with fetal brain NDVA diagnosed on ultrasound were included. We defined ventricular asymmetry as a difference of ≥2.0 mm between the lateral ventricles and ventricular dilation as ventricular width of >10.0 mm. Outcomes were evaluated with genetic exams (karyotype and chromosomal microarray analysis [CMA]) and fetal brain MRI.

RESULTS

During the study period, there were 145 cases diagnosed with NDVA on ultrasound that comprised the cohort study. The rate of abnormal karyotype was 1.8% (1/56) and of abnormal CMA was 10% (3/30). The rate of minor additional CNS findings did not differ between ultrasound and MRI (3.4 versus 2.8%, respectively, p = .74). No major additional fetal brain findings were detected on MRI performed after ultrasound.

CONCLUSIONS

In cases diagnosed with NDVA on ultrasound, no significant additional anomalies were detected on fetal brain MRI. The rate of abnormal genetic tests was relatively high and warrants further studies.

A Systematic Review of Methodology Used in Studies Aimed at Creating Charts of Fetal Brain Structures

Ultrasound-based assessment of the fetal nervous system is routinely recommended at the time of the mid-trimester anatomy scan or at different gestations based on clinical indications. This review evaluates the methodological quality of studies aimed at creating charts for fetal brain structures obtained by ultrasound, as poor methodology could explain substantial variability in percentiles reported. Electronic databases (MEDLINE, EMBASE, Cochrane Library, and Web of Science) were searched from January 1970 to January 2021 to select studies on singleton fetuses, where the main aim was to construct charts on one or more clinically relevant structures obtained in the axial plane: parieto-occipital fissure, Sylvian fissure, anterior ventricle, posterior ventricle, transcerebellar diameter, and cisterna magna. Studies were scored against 29 predefined methodological quality criteria to identify the risk of bias. In total, 42 studies met the inclusion criteria, providing data for 45,626 fetuses. Substantial heterogeneity was identified in the methodological quality of included studies, and this may explain the high variability in centiles reported. In 80% of the studies, a high risk of bias was found in more than 50% of the domains scored. In conclusion, charts to be used in clinical practice and research should have an optimal study design in order to minimise the risk of bias and to allow comparison between different studies. We propose to use charts from studies with the highest methodological quality.

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.

International standards for fetal brain structures based on serial ultrasound measurements from Fetal Growth Longitudinal Study of INTERGROWTH-21st Project

OBJECTIVE

To create prescriptive growth standards for five fetal brain structures, measured using ultrasound, in healthy, well-nourished women at low risk of impaired fetal growth and poor perinatal outcome, taking part in the Fetal Growth Longitudinal Study (FGLS) of the INTERGROWTH-21^st Project.

METHODS

This was a complementary analysis of a large, population-based, multicenter, longitudinal study. The sample analyzed was selected randomly from the overall FGLS population, ensuring an equal distribution among the eight diverse participating sites and of three-dimensional (3D) ultrasound volumes across pregnancy (range: 15-36 weeks' gestation). We measured, in planes reconstructed from 3D ultrasound volumes of the fetal head at different timepoints in pregnancy, the size of the parieto-occipital fissure (POF), Sylvian fissure (SF), anterior horn of the lateral ventricle, atrium of the posterior horn of the lateral ventricle (PV) and cisterna magna (CM). Fractional polynomials were used to construct the standards. Growth and development of the infants were assessed at 1 and 2 years of age to confirm their adequacy for constructing international standards.

RESULTS

From the entire FGLS cohort of 4321 women, 451 (10.4%) were selected at random. After exclusions, 3D ultrasound volumes from 442 fetuses born without a congenital malformation were used to create the charts. The fetal brain structures of interest were identified in 90% of cases. All structures, except the PV, showed increasing size with gestational age, and the size of the POF, SF, PV and CM showed increasing variability. The 3^rd , 5^th , 50^th , 95^th and 97^th smoothed centiles are presented. The 5^th centiles for the POF and SF were 3.1 mm and 4.7 mm at 22 weeks' gestation and 4.6 mm and 9.9 mm at 32 weeks, respectively. The 95^th centiles for the PV and CM were 8.5 mm and 7.5 mm at 22 weeks and 8.6 mm and 9.5 mm at 32 weeks, respectively.

CONCLUSIONS

We have produced prescriptive size standards for fetal brain structures based on prospectively enrolled pregnancies at low risk of abnormal outcome. We recommend these as international standards for the assessment of measurements obtained using ultrasound from fetal brain structures. © 2020 Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Imaging diagnosis of ventriculomegaly: fetal, neonatal, and pediatric

Ventriculomegaly is the term used to describe abnormal enlargement of ventricles in the brain. Neuroimaging, whether it is by ultrasound, computed tomography, or magnetic resonance imaging, is the key to its identification and can help to diagnose its cause and guide management in many cases. The implementation of the imaging modalities and potential differential considerations varies from the fetus, infant, and pediatric patient. Here we discuss how the imaging modalities can be used in these patient populations and review some of the differential considerations.

A methodological review of fetal neurosonographic studies: New directions in assessment of neurodevelopmental risk for mental health problems

Most mental disorders are now considered to have neurodevelopmental origins, with a growing body of research pointing to neural alterations that predate birth. However, lack of established methods for reliable investigation of fetal brain development has limited research into early neural vulnerability. Using a systematic approach and quantitative evaluation of study methodology, we review neurosonographic studies of fetal brain structure with objective quality measures. A total of 81 studies were identified. High quality studies were identified for measurement of the corpus callosum, cerebellum, vermis, ventricles and frontal cortex, with reference ranges provided to facilitate future clinical research. Fewer and lower quality studies were available for subcortical structures, prompting a need for further research to create reliable reference ranges. Development and adoption of reference ranges for fetal brain structures should facilitate future research in neurosonographic evaluation of fetal brain development and lead to a better understanding of neurodevelopmental risk and resilience processes for mental disorders.

Fetal Neuroimaging Update

OBJECTIVES

To review the current imaging techniques available for the evaluation of the fetal brain.

FINDINGS

Ultrasound remains the initial screening modality with routine scanning typically performed at 18-20 weeks gestation. When a central nervous system (CNS) abnormality is noted by ultrasound, MRI is increasingly being used to further clarify findings. Fetal MRI has the unique ability to provide high detailed anatomical information of the entire human fetus with high contrast resolution. This technique has grown due to the development of rapid single shot image acquisition sequences, improvement of motion correction strategies and optimizing shimming techniques.

CONCLUSIONS

The assessment of fetal CNS anomalies continues to improve. Advanced MRI techniques have allowed for further delineation of CNS anomalies and have become a cornerstone in the assessment of fetal brain well-being. Those interpreting fetal studies need to be familiar with the strengths and limitations of each exam and be sensitive to the impact discussing findings can have regarding perinatal care and delivery planning. Collaboration with neurologists, neurosurgeons, geneticists, counselors, and maternal fetal specialists are key in providing the best care to the families we treat.

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.

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.

Mild ventriculomegaly from fetal consultation to neurodevelopmental assessment: A single center experience and review of the literature

OBJECTIVE

The aim of our study was to determine the outcome of fetuses with isolated mild ventriculomegaly, with prenatal imaging work-up, prenatal consultation, delivery and clinical follow-up performed in a single tertiary referring center.

METHODS

Fetuses with isolated and non-progressive mild ventriculomegaly (10-15 mm) were included in the study. Inclusion criteria were as follows: singleton pregnancies, normal chromosomal analysis, normal serological evaluation of TORCH, fetal ultrasound and MRI excluding additional CNS or extra-CNS malformations. The prenatal consultation consisted in discussing the prognosis of ventriculomegaly, according to the literature. The postnatal follow-up protocol included a neuroradiological investigation (cranial ultrasound or MRI), neurological and pediatric examinations. The Griffiths Scales were used to assess the neurodevelopmental outcome.

RESULTS

Thirty newborns were included in follow-up. The postnatal neuroradiological investigations confirmed the ventriculomegaly as an isolated finding in all cases except one. Nineteen children were available for formal neurodevelopmental testing. In our case series, 93.3% of the children had a favorable outcome or mild anomalies. Two children (6.6%) with mild ventriculomegaly were diagnosed as having rare genetic conditions. The Griffiths developmental quotients were normal (mean General Quotient 98.3) at the latest assessment (mean age 20.8 months) in all but one case.

DISCUSSION

Most children in our case series had a favorable outcome, as described in the literature. Even though a large quantity of data is now available on ventriculomegaly, fetal consultation remains challenging and requires caution. The diagnostic work-up of pregnancies diagnosed with mild ventriculomegaly must be very meticulous and include TORCH evaluation, microarray, serial ultrasounds to exclude progression, and a fetal MRI. However, despite accurate screening, there are more complex conditions in which ventriculomegaly can be the only non-specific finding in fetal life, making postnatal follow up mandatory.

Neurodevelopmental outcome of fetal isolated ventricular asymmetry without dilation: a cohort study

OBJECTIVE

Fetal isolated ventricular asymmetry (IVA) is a relatively common finding in pregnancy, but data regarding its effect on neurodevelopmental outcome are scarce and founded principally on ultrasound-based studies. The purpose of this study was to assess the neurodevelopmental outcome of IVA cases in a magnetic resonance imaging (MRI)-based study.

METHODS

Cases referred for fetal brain MRI as part of the assessment of IVA without ventriculomegaly (lateral ventricular atrial diameter ≤ 10 mm), identified during routine ultrasound examination, were assessed for possible inclusion. Asymmetry was defined as a difference in width of ≥ 2 mm between the two lateral ventricles. Forty-three cases were included in the study group and compared with a control group of 94 normal cases without IVA. Children were assessed at ages 13-74 months using the Vineland-II Adaptive Behavior Scales (VABS-II).

RESULTS

VABS-II scores were within normal range. There was no significant difference in composite VABS-II score between the study and control groups (106.5 vs 108.0; P = 0.454). VABS-II scores did not differ between the groups when matched for gender and age at VABS-II interview (109.6 in study group vs 107.8 in control group; P = 0.690).

CONCLUSION

In cases of IVA without ventriculomegaly on MRI, neurodevelopmental test scores were normal and did not differ from cases without IVA. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Mild fetal ventriculomegaly: diagnosis, evaluation, and management

Ventriculomegaly is defined as dilation of the fetal cerebral ventricles and is a relatively common finding on prenatal ultrasound. The purpose of this document is to review the diagnosis, evaluation, and management of mild fetal ventriculomegaly. When enlargement of the lateral ventricles (≥10 mm) is identified, a thorough evaluation should be performed, including detailed sonographic evaluation of fetal anatomy, amniocentesis for karyotype and chromosomal microarray analysis, and a workup for fetal infection. In some cases, fetal magnetic resonance imaging may identify other central nervous system abnormalities and should be considered when this technology as well as expert interpretation is available. Follow-up ultrasound examination should be performed to assess for progression of the ventricular dilation. In the setting of isolated ventriculomegaly of 10-12 mm, the likelihood of survival with normal neurodevelopment is >90%. With moderate ventriculomegaly (13-15 mm), the likelihood of normal neurodevelopment is 75-93%. The following are Society for Maternal-Fetal Medicine recommendations: We suggest that ventriculomegaly be characterized as mild (10-12 mm), moderate (13-15 mm), or severe (>15 mm) for the purposes of patient counseling, given that the chance of an adverse outcome and potential for other abnormalities are higher when the ventricles measure 13-15 mm vs 10-12 mm (GRADE 2B); we recommend that diagnostic testing (amniocentesis) with chromosomal microarray analysis should be offered when ventriculomegaly is detected (GRADE 1B); we recommend testing for cytomegalovirus and toxoplasmosis when ventriculomegaly is detected, regardless of known exposure or symptoms (GRADE 1B); we suggest that magnetic resonance imaging be considered in cases of mild or moderate fetal ventriculomegaly when this modality and expert radiologic interpretation are available; magnetic resonance imaging is likely to be of less value if the patient has had a detailed ultrasound performed by an individual with specific experience and expertise in sonographic imaging of the fetal brain (GRADE 2B); we recommend that timing and mode of delivery be based on standard obstetric indications (GRADE 1C); we recommend that with isolated mild ventriculomegaly of 10-12 mm, after a complete evaluation, women be counseled that the outcome is favorable, and the infant is likely to be normal (GRADE 1B); we recommend that with isolated moderate ventriculomegaly of 13-15 mm, after a complete evaluation, women be counseled that the outcome is likely to be favorable but that there is an increased risk of neurodevelopmental disabilities (GRADE 1B).

Neuroimaging findings associated with congenital Zika virus syndrome: case series at the time of first epidemic outbreak in Pernambuco State, Brazil

PURPOSE

This study aimed to describe the prenatal and postnatal neuroimaging and clinical findings in a clinical series following congenital Zika virus syndrome during the first epidemic Zika virus (ZIKV) outbreak in the State of Pernambuco, Brazil.

METHODS

We (the authors) conducted a retrospective study of a prospectively collected case series of fetuses and neonates with microcephaly born to mothers with presumed/confirmed congenital ZIKV syndrome. Prenatal ultrasound findings were reviewed to identify potential central nervous system (CNS) abnormalities. Neonates underwent postnatal neuroimaging follow up by computed tomography (CT)-scan or magnetic resonance (MR) imaging.

RESULTS

The prenatal and postnatal outcomes of eight fetuses/neonates born to mothers with presumed/confirmed congenital ZIKV syndrome were examined. The mean gestational age at ultrasound was 31.3 weeks. Severe microcephaly was identified in seven fetuses (87.5%), while ventriculomegaly and brain calcifications were detected in all fetuses. The mean gestational age at delivery and head circumference were 38 weeks and 30.2 cm, respectively. All cases of microcephaly but one was confirmed postnatally. Brain CT scans or MRIs were performed in seven newborns, and all had periventricular and/or parenchymal calcifications, symmetrical or asymmetrical ventriculomegaly, pachygyria, and reduced sulcation and gyration. MR imaging aided the detection of one undetected case of corpus callosum dysgenesis and was essential in documenting reduced mantel of the cerebral cortex and reduced gyration and sulcation, especially involving the parietal lobe. In addition, MR imaging was also able to display irregular interfaces with the subcortical white matter, a finding consistent with polymicrogyria, more frequently seen at the level of the frontal lobe and atrophic and thinned pons.

CONCLUSION

Severe microcephaly and CNS abnormalities may be associated with congenital ZIKV syndrome.

Fetal cerebral ventricular atria width of 8-10mm: A possible prenatal risk factor for adolescent treated Attention Deficit Hyperactivity Disorder (ADHD)

The purpose of our research was to study the in-utero and long term post-natal outcome of fetal isolated cerebral ventricular atria width between 8 and 10mm. We conducted a retrospective, observational, case-control study, of low risk pregnant women, between 1993 and 2001. One hundred and forty one fetuses with isolated cerebral ventricular atria width between 8 and 10mm, corresponding to 2-4 standard deviations above the mean, and 309 controls, with atrial width below this level, were included for the analysis. Clinical data concerning pre and post-natal outcome was retrieved from computerized medical records. Matching of cases with controls was based on age, with a ratio of 2-3 controls per case. Statistical analysis included: T-test, Chi-Square, and Multiple Logistic Regression analysis. The study group was characterized by a predominance of male gender, left side involvement, and higher birth weight, compared to the control group. Long term post-natal follow-up at a mean age of 12.7 years (±1.9) demonstrated an adjusted odds ratio of 2.589 (95% CI 1.415-4.737, p=0.001), being diagnosed as Attention Deficit Hyperactivity Disorder (ADHD), and treated by Methylphenidate (Ritalin(®)), during childhood, compared to the control group (23.6% and 10.0% respectively) (p=0.001). Cerebral atria width was an independent factor, controlled for the only two significant variants between groups, gender and weight over 90th centile. In conclusions, our preliminary results show that fetuses with prenatal finding of isolated cerebral ventricular atria width between 8 and 10mm are more likely of being diagnosed and treated as ADHD during childhood.

Normal development

Numerous events are involved in brain development, some of which are detected by neuroimaging. Major changes in brain morphology are depicted by brain imaging during the fetal period while changes in brain composition can be demonstrated in both pre- and postnatal periods. Although ultrasonography and computed tomography can show changes in brain morphology, these techniques are insensitive to myelination that is one of the most important events occurring during brain maturation. Magnetic resonance imaging (MRI) is therefore the method of choice to evaluate brain maturation. MRI also gives insight into the microstructure of brain tissue through diffusion-weighted imaging and diffusion tensor imaging. Metabolic changes are also part of brain maturation and are assessed by proton magnetic resonance spectroscopy. Understanding and knowledge of the different steps in brain development are required to be able to detect morphologic and structural changes on neuroimaging. Consequently alterations in normal development can be depicted.

Evolution of fetal ventricular dilatation in relation to severity at first presentation

BACKGROUND

To assess the outcome of 360 cases of fetal ventriculomegaly in a tertiary referral center.

METHODS

Cases of fetal ventriculomegaly between June 1993 and December 2011 were identified from the departmental fetal database. The fetal medicine reports and obstetric notes were reviewed to ascertain the antenatal progression of the ventriculomegaly as well as the outcome of the pregnancy. Ventriculomegaly was defined by a lateral ventricular wall atrial measurement of greater than 10 mm. Cases were subdivided into mild (>10 to <12 mm), moderate (≥12 to <15 mm), and severe (≥15 mm). Termination of pregnancy was offered in cases where there were associated anomalies, aneuploidy, or the ventriculomegaly progressed.

RESULTS

Of the 360 cases, 189 were mild, 79 were moderate, and 92 were severe. Sixty-four percent of cases had associated anomalies. Forty-six percent of cases in the mild group and 26% in the moderate group resolved. Only one case in the severe group improved. The mean rate of progression in the mild group was 1.07 (SD 1.03) mm/week, whereas in the moderate group progression was at a mean rate of 1.41 (SD 0.77) mm/week. Progression of severe ventriculomegaly was significantly higher at a mean rate of 3.26 (SD 2.92) mm/week (p = 0.007).

CONCLUSIONS

The majority of fetuses with mild ventriculomegaly normalized, whereas the majority of moderate cases remained stable. The rate of progression of ventriculomegaly increased with severity. Fetuses with ventriculomegaly should be offered serial scans to allow the progression of ventriculomegaly to be ascertained with the option of late termination of pregnancy.

Perinatal characteristics of fetuses with borderline ventriculomegaly detected by routine ultrasonographic screening of low-risk populations

AIM

Fetal borderline ventriculomegaly represents a frequent dilemma in perinatal management. The present study aimed to evaluate the clinical significance of fetal borderline ventriculomegaly in a low-risk Japanese population and to identify the risk factors for associated anomalies.

METHODS

Data of cases of fetal borderline ventriculomegaly detected at 26-28 weeks of gestation by routine ultrasonographic screening of low-risk singleton pregnancies between 2006 and 2012 were retrospectively collected. Ventricular width, in utero progression, associated anomalies, chromosomal abnormalities, and perinatal and postnatal outcomes were assessed. The ventricular width, in utero progression and other perinatal characteristics were compared between the isolated and non-isolated groups.

RESULTS

Among the total 6020 singleton low-risk pregnancies, we noted that 42 had borderline ventriculomegaly. Six (14%) of these cases had other defects by subsequent detailed examination. Ventriculomegaly resolved or regressed in 35 (83%) and progressed in four (10%) cases, of which three were associated with other anomalies. The median ventricular width was 12.8 mm (range, 10.0-14.7) in the six non-isolated cases and 10.5 mm (range, 10.0-13.3) in the 36 isolated cases; the differences were statistically significant. A ventricular width of 12 mm or more and in utero progression were more frequently observed in non-isolated cases than in isolated cases.

CONCLUSION

Fetal borderline ventriculomegaly frequently resolves in utero. A ventricular diameter of more than 12 mm and in utero progression are risk factors for additional anomalies. After the initial diagnosis of borderline ventriculomegaly, the pregnancy should be carefully followed up to determine whether the ventricle size is resolved, remains stable or increases.

Clinical outcomes of mild isolated cerebral ventriculomegaly in the presence of other neurodevelopmental risk factors

OBJECTIVES

The purpose of this study was to evaluate neuropsychological test data in school-aged children whose fetal sonograms revealed mild isolated cerebral ventriculomegaly without asymmetry of the lateral ventricles.

METHODS

Nine of 52 children 6 years and older with sonographic evidence of mild isolated cerebral ventriculomegaly without asymmetry of the lateral ventricles were able to be recruited for follow-up school-aged neuropsychological testing. The children received a half-day battery of neuropsychological tests, including the Wechsler Abbreviated Scales of Intelligence; Beery-Buktenica Developmental Test of Visual Motor Integration, Fifth Edition; Wide Range Achievement Test, Fourth Edition; and Integrated Visual and Auditory Continuous Performance Test. Parents completed the Conners 3 Parent Short Form and the Personality Inventory for Children, Second Edition.

RESULTS

In this small group, other risk factors for neurodevelopmental disorders were often present, including preterm birth, perinatal hypoxia, and a family history of psychiatric disease or substance abuse. Within this sample, the proportion of children with a pattern of test results showing poorer nonverbal intelligence than verbal intelligence scores and poorer math than reading performance, as well as meeting criteria for a diagnosis of attention deficit/hyperactivity disorder, was higher than the basal rates of these problems among children in general.

CONCLUSIONS

Particularly given the complexity of various factors affecting neurodevelopment, follow-up neuropsychological evaluation is warranted in children with sonographic evidence of mild isolated cerebral ventriculomegaly without asymmetry of the lateral ventricle (eg, in the context of poor school performance).

Imaging diagnosis of congenital brain anomalies and injuries

Fetal brain is rapidly developing and changing its appearance week by week during pregnancy. The brain is the most important organ but it is quite hard to observe detailed structure of this organ by conventional transabdominal sonography. Transvaginal high-resolution ultrasound and three-dimensional (3D) ultrasound has been a great diagnostic tool for evaluation of three-dimensional structure of fetal central nervous system (CNS). This method has contributed to the prenatal assessment of congenital CNS anomalies, intracranial vascular anomalies and acquired brain damage in utero. It is possible to observe the whole brain structure by magnetic resonance imaging in the post half of pregnancy but transvaginal high-resolution 3D ultrasound is certainly powerful modality as well for understanding brain anatomy. Longitudinally and carefully evaluation of neurological short- or long-term prognosis should be required according to precise prenatal diagnosis, for proper counseling and management based on precise evidence.

Neuroimaging of ventriculomegaly in the fetal period

Fetal cerebral ventriculomegaly (VM) is defined as an enlargement of the lateral ventricles of the developing fetal brain. It is diagnosed when the width of one or both lateral ventricles, measured at the level of the atrium, is ≥10 mm. VM is defined as mild when the atrial width is 10-15 mm and severe when >15 mm. VM is a non-specific sonographic sign which is common to various pathological conditions. It is frequently associated with neural and extraneural anomalies. The rate of associated malformations is higher (≥60%) in severe VM and lower (about 40%) in cases of mild VM. When an abnormality is associated with severe VM the incidence of aneuploidies is high (>15%); in isolated mild VM the mean value of aneuploidy is 2.7%. The rate of infections in severe VM is 10-20%, in mild forms 1-5%. Since the prognosis in cases of VM depends mainly on the associated anomalies, a careful examination of the fetus, particularly of the brain, is mandatory. Magnetic resonance imaging can be a useful diagnostic tool complementary to ultrasound in order to recognize subtle brain anomalies, such as neuronal migration and proliferation disorders.

Prognosis of isolated mild to moderate fetal cerebral ventriculomegaly: a systematic review

AIMS

To ascertain risk of aneuploidy, infection and neurological abnormality for the fetus diagnosed with isolated mild (10.1-12.0 mm) to moderate (12.1-15.0 mm) cerebral ventriculomegaly and to compare the neurological outcome between symmetrical vs. asymmetrical and stable vs. progressive ventriculomegaly.

METHODS

A systematic review was conducted. Literature was identified by searching two bibliographical databases between 1980 and 2009 without language restrictions. The data extracted were inspected for heterogeneity. Overall rates and confidence intervals (CIs) for each prognostic factor were calculated. When comparative data existed, the odds ratio (OR) was calculated.

RESULTS

The search strategy yielded 2150 relevant citations of which 28 studies were included in the review. The overall rate of infection and chromosomal abnormality was 1.5 and 5% (95% CI 3, 7), respectively. The risk of neurological abnormality regardless of karyotype or infection screen was 14% (95% CI 10, 18) and this reduced to 12% (95% CI 9, 15) when both chromosomes and infection screen were normal. The risk of neurological abnormality was significantly lower in stable compared to progressive ventriculomegaly [OR 0.29 (95% CI 0.15, 0.58)]. No significant differences were detected when symmetrical vs. asymmetrical ventriculomegaly were compared [OR 0.91 (95% CI 0.34, 2.41)].

CONCLUSION

This systematic review provides the physician with some estimates of prognosis in cases of isolated mild to moderate ventriculomegaly.

Fetal magnetic resonance imaging of acquired and developmental brain anomalies

During the last decade, increasing interest in magnetic resonance imaging has emerged for the evaluation of fetal abnormalities detected on ultrasound. The advent of single-shot rapid acquisition sequences has greatly facilitated our ability to obtain detailed imaging information of the fetal brain. To date, fetal magnetic resonance imaging has shown to have an important role in the investigation of cerebral abnormalities suspected by sonography, and in the detection of subtle brain anomalies associated with high-risk pregnancies. Magnetic resonance imaging has proved to be a useful adjunct to sonography during the prenatal period of development, especially for the detection of acquired disorders.

Counseling in isolated mild fetal ventriculomegaly

In this Review we aim to provide up-to-date and evidence-based answers to the common questions regarding the diagnosis of isolated mild fetal ventriculomegaly (VM). A literature search was performed to identify all reports of antenatal VM in the English language literature. In addition, reference lists of articles identified using the search were scrutinized to further identify relevant articles. Fetal mild VM is commonly defined as a ventricular atrial width of 10.0-15.0 mm, and it is considered isolated if there are no associated ultrasound abnormalities. There is no good evidence to suggest that the width of the ventricular atria contributes to the risk of neurodevelopmental outcome in fetuses with mild VM. The most important prognostic factors are the association with other abnormalities that escape early detection and the progression of ventricular dilatation, which are reported to occur in about 13% and 16% of cases, respectively. Most infants with a prenatal diagnosis of isolated mild VM have normal neurological development at least in infancy. The rate of abnormal or delayed neurodevelopment in infancy is about 11%, and it is unclear whether this is higher than in the general population. Furthermore, the number of infants that develop a real handicap is unknown. There are limitations of existing studies of mild VM. Although they address many of the relevant questions regarding the prognosis and management of fetal isolated mild VM, there is a lack of good-quality postnatal follow-up studies. The resulting uncertainties make antenatal counseling for this abnormality difficult.

Normal development of the fetal brain by MRI

The fetal brain is a dynamic structure, which can now be imaged using magnetic resonance imaging (MRI). This article will review techniques of fetal MRI as well as several key aspects of brain development and their appearance on MRI. An understanding of normal fetal brain development is essential to correctly identifying developmental abnormalities.

Perinatal and neurodevelopmental outcome with isolated fetal ventriculomegaly: A systematic review

OBJECTIVE

To establish the perinatal and neurodevelopmental outcomes of fetuses diagnosed with isolated ventriculomegaly (IVM).

METHODS

A systematic review of cohort, case/control studies, case series and case reports of IVM (unilateral or bilateral enlargement of the lateral ventricle, >or=10 mm, with no additional diagnosis at the time of the initial ultrasound), identified by searching, without language restrictions, The Cochrane Library, MEDLINE and Embase databases in June 2004.

RESULTS

No cohort study was retrieved but 577 cases were identified in one case/control study and 29 case series/case reports. Of 207 cases with follow-up and known gestational age at diagnosis, normal developmental outcomes were found in 82%, mild impairments in 9% and moderate/severe impairments in 10%. Prenatal diagnosis could possibly have reduced the risk of moderate/severe impairments to 7%. In 137 cases followed to at least 20 months of age, 79% had normal neurodevelopment, 10% were mildly delayed and 11% had moderate/severe developmental delays.

CONCLUSIONS

Outcome was favorable in 85% of IVM cases, decreasing to 79% when cases were followed to at least 20 months of age. We recommend prospective cohort studies with new diagnostic modalities to better identify the underlying conditions relating to moderate/severe impairments in the remaining cases.

Visual, motor and perceptual abilities at school age in children with isolated mild antenatal ventricular dilatation

BACKGROUND

The detection of prenatal ventriculomegaly raises anxiety about possible neurological sequelae. A few studies have investigated possible neurodevelopmental sequelae in the first years after birth but no systematic assessment has been performed at school age.

AIMS

The aim of this study was to assess minor neurological signs, perceptual and visual function in a cohort of children with isolated mild antenatal ventricular dilatation examined at school age.

STUDY DESIGN

Seventeen children with evidence of mild antenatal ventriculomegaly in the second and third trimester of pregnancy were included in the study.

OUTCOME MEASURES

Children were assessed at school age (range 5 years 3 months-11 years, 11 months) using a structured neurological examination for minor neurological signs and age specific tests assessing perceptual motor abilities (Developmental Test of Visual-Motor Integration; Movement Assessment Battery for Children).

RESULTS

Only one of the 17 children had abnormal results. The remaining 16 had normal results on all the tests, irrespective of the magnitude and the symmetry of the dilatation or of its evolution on neonatal scan.

CONCLUSIONS

Our results suggest that children who had mild isolated prenatal ventricular dilatation are unlikely to develop even minor motor or perceptual difficulties at school age.

Prenatal mild ventriculomegaly predicts abnormal development of the neonatal brain

BACKGROUND

Many psychiatric and neurodevelopmental disorders are associated with mild enlargement of the lateral ventricles thought to have origins in prenatal brain development. Little is known about development of the lateral ventricles and the relationship of prenatal lateral ventricle enlargement with postnatal brain development.

METHODS

We performed neonatal magnetic resonance imaging on 34 children with isolated mild ventriculomegaly (MVM; width of the atrium of the lateral ventricle >/= 1.0 cm) on prenatal ultrasound and 34 age- and sex-matched control subjects with normal prenatal ventricle size. Lateral ventricle and cortical gray and white matter volumes were assessed. Fractional anisotropy (FA) and mean diffusivity (MD) in corpus callosum and corticospinal white matter tracts were determined obtained using quantitative tractography.

RESULTS

Neonates with prenatal MVM had significantly larger lateral ventricle volumes than matched control subjects (286.4%; p < .0001). Neonates with MVM also had significantly larger intracranial volumes (ICV; 7.1%, p = .0063) and cortical gray matter volumes (10.9%, p = .0004) compared with control subjects. Diffusion tensor imaging tractography revealed a significantly greater MD in the corpus callosum and corticospinal tracts, whereas FA was significantly smaller in several white matter tract regions.

CONCLUSIONS

Prenatal enlargement of the lateral ventricle is associated with enlargement of the lateral ventricles after birth, as well as greater gray matter volumes and delayed or abnormal maturation of white matter. It is suggested that prenatal ventricle volume is an early structural marker of altered development of the cerebral cortex and may be a marker of risk for neuropsychiatric disorders associated with ventricle enlargement.

FETAL NEUROIMAGING

Imaging technologies have been remarkably improved and contribute to prenatal evaluation of fetal central nervous system (CNS) development and assessment of CNS abnormalities in utero.

Postnatal clinical and imaging follow-up of infants with prenatal isolated mild ventriculomegaly: a series of 101 cases

BACKGROUND

Postnatal imaging and clinical outcome of fetuses with isolated mild ventriculomegaly (IMV) have never been systematically analysed.

OBJECTIVE

To evaluate the postnatal clinical outcomes of a large cohort of fetuses with IMV and to correlate them with pre- and postnatal imaging.

MATERIALS AND METHODS

We report a prospective study of 101 fetuses with IMV (10-15 mm ventriculomegaly with otherwise normal US, MRI, karyotype and TORCH screening). IMV was divided into minor (10-11.9 mm) and moderate (12-15 mm) ventriculomegaly. Ventriculomegaly was considered uni- or bilateral, stable, progressive, regressive or resolved according to the prenatal US follow-up. Clinical follow-up was performed by a neuropaediatrician. Postnatal imaging included cranial US (n = 71) and MRI (n = 76).

RESULTS

The outcome of minor and moderate IMV was excellent in 94% and 85% of infants, respectively. It was not different between uni- and bilateral IMV, and between stable, regressive and resolved IMV, and was independent of gestational age at diagnosis and gender. Fixed neurological abnormalities were observed in nine infants. Postnatal MRI showed white-matter abnormalities in 14 infants, including 6 of the 9 infants with a poor outcome.

CONCLUSION

The prognosis was slightly better in minor IMV than in moderate IMV. Postnatal MRI showed white-matter abnormalities in two-thirds of the infants with a poor outcome.

Reference ranges for fetal ventricular width: a non-normal approach

OBJECTIVES

Normal ranges for fetal cerebral ventricular width are usually based on parametric methods, which define cut-off values based on means and standard deviations. We aimed to construct reference charts based on a large sample and using a method that better fits with skewed measurements.

METHODS

In November 2001-December 2005, a single operator, who was unaware of the subsequent analysis, performed prospectively and routinely fetal cerebral ventricular width measurements. We used the LMS method (which summarizes the changing distribution of a variable of interest according to a covariate (gestational age) using three curves representing the median (M), the coefficient of variation (S) and skewness (L)) to describe the distribution of measurements with gestational age. The LMS method provides a general method for fitting smooth centile curves to reference data. It utilizes the power transformation family of Box and Cox to allow the skewness of the measurement distribution, as well as the median and variability, to vary with age. The theoretical proportion of fetal ventricular widths > or = 10 mm based on the LMS method and on methods based on the assumption of normality were compared with the actual proportion using binomial tests. The influence on ventricular size of gestational age and fetal gender and presentation was assessed using robust regression methods.

RESULTS

Included in the study were 4769 ventricular measurements, 42 (0.88%) of which were > or = 10 mm. The LMS method allowed us to fit the skewness of the measurements and identified slight changes throughout gestation. The actual proportion of measurements > or = 10 mm was not different from that expected according to the LMS method (0.88% vs. 1%, P = 0.25), whereas it was significantly different from that based on the classical normal approximation (0.88% vs. 0.4%, P < 0.0001). There was a significant difference with gender (males: + 0.29 +/- 0.042 mm as compared to females, P < 0.0001), but there was no difference with fetal presentation (P = 0.4).

CONCLUSION

We present new reference values for fetal ventricular width based on the LMS method. A fixed cut-off value of 10 mm identifies around 1% of the population throughout gestation, which is more than that calculated in previous studies.

The dynamic fetal brain

PURPOSE

To evaluate fetuses with normal intracranial anatomy in the second trimester that became abnormal in the third trimester.

METHODS

We sonographically examined 6 fetuses with a normal second-trimester head sonogram that presented later in pregnancy with an abnormal head sonogram.

RESULTS

Four categories of intracranial pathology were depicted: obstructive hydrocephalus, intraventricular intracranial hemorrhage, non-intraventricular intracranial hemorrhage, and porencephaly.

CONCLUSIONS

Despite a normal midtrimester intracranial examination, evaluation of the fetal intracranial contents should be undertaken in subsequent sonographic examinations, because significant pathology can develop spontaneously.

Currarino syndrome shown by prenatal onset ventriculomegaly and spinal dysraphism

The most frequent cause of ventriculomegaly is spina bifida when associated with Arnold-Chiari type II malformation. We report on a prenatal diagnosis of severe ventriculomegaly in association with spinal dysraphism that was indicative of a Currarino syndrome (CS) due to a c.584delA, p.H195fsX28 truncated mutation within the HLXB9 gene. Physiopathology of the ventriculomegaly is discussed in reference to the fetopathological examination and CS embryopathology. In the present case, prognosis was poor and pregnancy termination was authorized. However, such a decision may be controversial in fetuses with less severe malformations on sonographic examination, since mutations in the HLXB9 gene can predict neither the severity nor the long-term prognosis of the disease. Due to a lack of genotype-phenotype correlation and the broad variability of phenotype in heterozygotes, clinical and genetic investigations among relatives are mandatory in all HLXB9 gene mutation cases, to detect asymptomatic CS cases and to prevent the occurrence of severe complications.

Fetal ventriculomegaly: prognosis in cases in which prenatal neurosurgical consultation was sought

OBJECT

The prognosis of fetal ventriculomegaly (FVM) varies because of the disease's heterogeneity and the diversity of accompanying anomalies. Moreover, the cases that are referred to neurosurgeons may have different clinical features from those typically encountered by obstetricians. The object of this study was to delineate the prognosis of FVM in cases for which neurosurgical consultation was sought.

METHODS

Forty-four cases of FVM that were diagnosed before birth and referred to neurosurgeons for prenatal consultation were analyzed retrospectively. Twenty-five of the 44 patients had accompanying anomalies, but in only three (12%) of the cases were they detected prenatally. Postnatal imaging studies revealed that agenesis of the corpus callosum (nine cases) was the most common associated anomaly. Neuronal migration disorders, periventricular leukomalacia, and arachnoid cysts were present in four cases each, and aqueductal stenosis was present in three cases. Thirty-three patients were followed up longer than 11 months; in 15 (45%) delayed cognitive and/or motor development was documented, and all had accompanying anomalies. All 10 of the patients with isolated FVM exhibited normal development during the follow-up period. Eleven (25%) of the 44 patients underwent neurosurgical interventions for ventriculomegaly, which included ventriculoperitoneal shunt placement in seven cases. Four patients (9%) died.

CONCLUSIONS

The authors conclude that delayed development and disturbed functional status in patients in whom FVM was diagnosed prenatally are closely related to the presence of certain accompanying anomalies. On postnatal examination, more than half of the patients in whom the diagnosis of FVM was based on ultrasonography findings and whose parents were offered prenatal neurosurgical consultation were found to have additional anomalies that were not detected prenatally. Because of the possibility of additional undiagnosed anomalies, consulting neurosurgeons should be cautious in giving a prognosis in cases of FVM, even when prenatal ultrasonography reveals isolated ventriculomegaly and tests for intrauterine infection and chromosomal abnormality yield negative results.

Prenatal isolated mild ventriculomegaly: outcome in 167 cases

OBJECTIVE

To define the contribution of prenatal investigation and evaluate the prognosis of isolated mild ventriculomegaly (IMV).

DESIGN

Retrospective study.

SETTING

University hospital between January 1992 and December 2002.

POPULATION

One hundred and sixty-seven cases of prenatal unilateral or bilateral IMV without any associated anomaly at the time of initial diagnosis.

METHODS

Complementary investigations were performed: amniocentesis with karyotyping, screening for viruses and acetylcholinesterase electrophoresis, magnetic resonance imaging (MRI), and ultrasonography every 3-4 weeks.

MAIN OUTCOME MEASURES

Results of prenatal investigations, pregnancy outcome, and postnatal psychomotor development.

RESULTS

IMV was diagnosed around 26.5 weeks. Amniocentesis revealed four chromosomal anomalies and two cytomegalovirus infections. MRI diagnosed brain-associated anomalies in 15 cases and ultrasonographic monitoring highlighted malformations not initially diagnosed in 28 cases. Termination of pregnancy (TOP) was considered in 21 pregnancies (12.6%). Indications were aneuploidy, fetal infectious disease or associated malformations. In women for whom a TOP was considered, consanguinity, fetus of female sex and frontal horn enlargement were statistically more frequent, ventriculomegaly was more often bilateral and asymmetrical, atrial width, and the rate of progressive ventricular enlargement were significantly higher. One hundred and one children with prenatal IMV were assessed between 19 and 127 months (mean age 54.68 +/- 2.87 months). Twelve children had neurological disease or psychomotor delay and 89 children had a normal psychomotor development. Poor neurological outcome was more often associated with atrial width greater than or equal to 12 mm, asymmetrical bilateral enlargement, and progression of the ventriculomegaly.

CONCLUSION

The detection of IMV raises the question of the child's psychomotor development and justifies meticulous prenatal investigation. In addition to associated anomalies, three criteria are often associated with an unfavourable outcome: atrial width greater than 12 mm, progression of the enlargement, and asymmetrical and bilateral ventriculomegaly.

Isolated choroid plexus separation on second-trimester sonography: natural history and postnatal importance

OBJECTIVE

This study was undertaken to investigate the natural history and clinical importance of choroid plexus separation (a > or = 3 mm distance between the choroid plexus and medial wall of the lateral ventricle) as an isolated finding in the second trimester.

METHODS

This was a 5-year retrospective review of an ultrasound database, looking for singleton fetuses with a menstrual age of 16 to 26 weeks and a finding of isolated choroid plexus separation.

RESULTS

There were 78 cases available for study. The finding of choroid plexus separation was usually transient. Resolution was noted in 37% of the cases that were rescanned within 2 weeks and 71% of the cases that were rescanned more than 2 weeks after the initial diagnosis. Two abnormal karyotypes (trisomy 21 and 47,XXY) and 3 cases with abnormal development not associated with an abnormal karyotype were noted on neonatal follow-up. Cases with abnormal development were quite varied in their presentation.

CONCLUSIONS

The finding of isolated choroid plexus separation is usually temporary, resolving in most cases within 4 weeks of the initial diagnosis. Most infants with this finding have no abnormalities. The clinical implication of the lone case of trisomy 21 was limited by a major preexisting risk in this patient. The 3 cases of abnormal development had varying presentations; the causal nature of this association is not yet clear. No trends were noted between the changing choroid plexus appearance with time and abnormal neonatal outcome, but the number of abnormal cases was quite limited.

Fetal biometry: size and configuration of the third ventricle

PURPOSE

To evaluate the normal configuration and size of the third ventricle in second and third trimester fetuses in a normal population, and to compare our values with those of previously published studies.

MATERIAL AND METHODS

Evaluation of fetal third ventricular width and configuration was obtained by antenatal ultrasonography in 474 fetuses with gestational age between 12 weeks and term (mean 28 weeks). Percentiles for third ventricle width were estimated by combining separate fractional polynominal regression models fitted to the mean and standard deviation, assuming that the measurements had a normal distribution at each gestational age. Appearance of the third ventricle was correlated with each gestational age.

RESULTS

The third ventricle could be visualized in 471 (99%) of 474 fetuses. The 97th percentile of the third ventricle in preterm fetuses was measured as 3.6 mm in size. The third ventricle was seen as a single echogenic line in 153 (32.4%) of 474 fetuses. Two-hundred-and-ninety-nine (61.5%) of all fetuses had parallel echogenic lines outlining a fluid-filled lumen. V-shaped third ventricular configuration was seen in only 28 (5.9%) of the fetuses. From 24 weeks to term, parallel echogenic lines were the most commonly (83.7% to 79.6%) encountered configuration for the third ventricle.

CONCLUSION

The 97th percentile of the third ventricle in preterm fetuses was measured as 3.6 mm in size. In the early second trimester, 77% of the fetuses had a single echogenic line appearance on ultrasonography. As the brain and ventricular structures mature, a parallel echogenic line becomes the prominent ultrasonography appearance (>80% of fetuses) in third trimester healthy fetuses.

Imaging of fetal cerebral ventriculomegaly: a guide to management and outcome

Ultrasound imaging is the screening modality of choice for initial evaluation of the fetal central nervous system. However, there are times when fast magnetic resonance imaging (MRI) provides information additional to that available from ultrasound. This review will: (1) discuss the ultrasound evaluation of ventriculomegaly and its associated anomalies; (2) illustrate and expand upon the type of additional information MRI can provide beyond that which is available from ultrasound; and (3) discuss how this additional information can alter diagnosis as well as change maternal counselling and case management.

Magnetic resonance evaluation of fetal ventriculomegaly-associated congenital malformations and lesions

Fetal MRI provides diagnostic quality images of the brain which permit differentiation between the various etiologies of ventriculomegaly: hydrocephalus, congenital malformation, and destructive processes.

[Role of "subtle" ultrasonographic signs during antenatal screening for trisomy 21 during the second trimester of pregnancy: meta-analysis and CPDPN protocol of the Grenoble University Hospital]

OBJECTIVE

A meta-analysis about subtle ultrasonographic signs in second trimester of pregnancy.

MATERIALS AND METHODS

196 articles dealing with the subject--from 1985 to July 2002--were studied. Data on the 11 reported signs were collected from 92 theoretically and/or statistically valid studies. Then, the studies were selected according to several criteria: isolated characteristic, defined thresholds, calculable sensitivity and specificity. After checking for homogeneity, a likelihood ratio was calculated for some of the signs.

RESULTS

This meta-analysis of the second trimester ultrasonographic signs of Down's syndrome enabled us to estimate the likelihood ratio (LHR) of six signs. At 22 weeks'gestation (WG) these signs are: pyelectasis equal to or greater than 5 mm; nuchal fold thickness equal to or greater than 6 mm; persistence of choroid plexus cysts; shortness of the femur and humerus below the tenth percentile; hyperechogenic bowe; and nasal bone length less than 2.5 mm.

CONCLUSION

These validated ultrasonographic signs are independent of nuchal translucency thickness at 12 WG and of maternal serum biochemistry. This allows to calculate a combinate risk for nuchal translucency, maternal serum biochemistry and second trimester ultrasonographic signs when they are validated.

Fetal cerebral ventriculomegaly: outcome in 176 cases

OBJECTIVE

To evaluate the outcome of fetuses affected by different degrees of ventriculomegaly.

METHODS

We studied 176 fetuses with ventriculomegaly and evaluated the pregnancy outcome and the neurodevelopmental outcome at age > or = 24 months. The population was divided into three groups according to ventricular width: A (mild ventriculomegaly, 10 to 12 mm); B (moderate, 12.1 to 14.9 mm) and C (severe, > or = 15 mm).

RESULTS

Ventriculomegaly was more often an isolated finding in Group A (44/75; 58.7%) than in Group B (10/41; 24.4%) and Group C (24/60; 40%). When the ventriculomegaly was an isolated finding, 97.7% of fetuses with mild, 80% with moderate and 33.3% of those with severe dilatation were alive at > or = 24 months. The neurodevelopmental outcome was normal in 93% of Group A, 75% of Group B and 62.5% of Group C.

CONCLUSIONS

Our results suggest that the definition of borderline ventriculomegaly should be limited to ventricular width below 12 mm. Cases with measurements above this value are more often associated with malformations and have a normal neurodevelopmental outcome less frequently.

Sonography of the fetal central nervous system

This article presents a general overview of fetal sonography and an approach to the sonographic evaluation of the fetal central nervous system. Annotated images of anomalies of the fetal head, brain, spine, face, and neck are shown. Sonographic technique,including the choice of transducers and imaging windows is presented. The complementary relationship of fetal neurosonography and fetal MR imaging is covered, and the strengths and weaknesses of each modality are discussed.

The role of magnetic resonance imaging in the evaluation of isolated mild ventriculomegaly

OBJECTIVE

Isolated mild ventriculomegaly is defined as dilatation of the lateral ventricle from 10 to 15 mm, with no other structural abnormalities observed at the time of diagnosis. Its reported frequency is between 1 per 50 and 1 per 700 deliveries. There are no universal recommendations for evaluation of isolated mild ventriculomegaly. Targeted sonography, karyotype analysis, and viral antigen testing, particularly for cytomegalovirus, are most often used for further investigation of this finding. We studied the role of magnetic resonance imaging as part of the prenatal evaluation of isolated mild ventriculomegaly.

METHODS

Thirty-six pregnant women were referred to 2 Hadassah hospitals between 1999 and 2002 for evaluation of isolated mild ventriculomegaly. They underwent targeted sonography to exclude other anomalies, genetic amniocentesis for fetal karyotype, and serologic cytomegalovirus tests. Mild ventriculomegaly was the only pathologic finding diagnosed. Fetal brain magnetic resonance imaging was performed to evaluate the correlation between sonographic and magnetic resonance imaging findings and the additional contribution of magnetic resonance imaging in evaluating isolated mild ventriculomegaly.

RESULTS

Thirty-six magnetic resonance imaging studies were performed. All tests were adequate for evaluation. In 3 (8.3%) of 36 cases, magnetic resonance imaging showed additional findings: in a severely obese woman, ventricular dilatation up to 18 mm and periventricular cystic lesions with abnormal sulcation suggestive of diffuse parenchymal abnormality were diagnosed, and in 2 cases, bleeding in germinal centers was found. On subsequent sonographic examination, no other finding but isolated mild ventriculomegaly was diagnosed. In the remaining 33 women (91.7%), magnetic resonance imaging studies correlated well with sonographic findings. Further sonographic follow-up in this subgroup failed to reveal any other pathologic findings.

CONCLUSIONS

Our study supports the view that magnetic resonance imaging should be considered as part of the evaluation of isolated mild ventriculomegaly, especially when objective difficulties preclude detailed sonographic examination.