Reference charts for fetal corpus callosum length: a prospective cross-sectional study of 2950 fetuses

Partial agenesis of the corpus callosum: Prenatal ultrasound characteristics, associations, and outcome

INTRODUCTION

To investigate prenatal ultrasound characteristics, associated abnormalities, and outcomes of partial agenesis of the corpus callosum (pACC).

MATERIAL AND METHODS

A total of 118 fetuses with pACC diagnosed using prenatal ultrasound were studied, and their prenatal ultrasound characteristics, associated abnormalities, genetics, and outcomes were collected. The fetuses were categorized into three groups according to gestational age: <24 weeks, 24-28 weeks, and >28 weeks, and the brain transverse plane ultrasound signs were compared among the three groups.

RESULTS

Prenatal ultrasound revealed the presence of abnormal cavum septi pellucidi (CSP), distention of the interhemispheric fissure (IF), dilated and elevated third ventricle (TV), and ventriculomegaly in 102 (86.4%), 91 (77.1%), 56 (47.4%), and 42 (35.6%) cases, respectively, in the transverse plane of the brain. Among the cases with dilatation and elevation of the TV, 38 (67.8%) showed posterior displacement, manifested by a cystic mass in the midline that communicated with the TV. There were statistically significant differences in the incidence of ventriculomegaly and abnormal CSP among the three groups at <24 weeks, 24-28 weeks, and >28 weeks. However, there were no statistically significant differences in the distention of the IF and TV among the three groups. Moreover, our cohort studies demonstrated that 32.2% (38/118), 18.6% (22/118), and 17.8% (21/118) of the cases were associated with intracranial, extracranial, and intra-extracranial anomalies, respectively. The most common intracranial and extracranial anomalies were cerebral cortical dysplasia and cardiovascular anomalies. Genetic analysis demonstrated that 37.8% (17/41) of patients had genetic abnormalities. 25% (4/16) and 52% (13/25) of isolated and non-isolated pACC cases showed genetic abnormalities. Eight isolated cases were born, with an average age of 28 months, and their neurological development was normal.

CONCLUSIONS

Abnormal CSP was the most common indirect sign of pACC. A cystic mass in the midline communicating with the TV can be another indirect sign of a pACC. pACC is likely to be accompanied by intracranial and extracranial abnormalities. The detection rate of genetic abnormalities was higher in non-isolated pACC cases than in isolated cases. Isolated pACC has a good prognosis but requires long-term follow-up of neurological development.

Outcome of Children With Prenatally Diagnosed Saccular Limited Dorsal Myeloschisis: The Importance of Accurate Diagnosis

OBJECTIVE

To describe outcomes at 36 months of age in children with prenatally diagnosed Limited Dorsal Myeloschisis (LDM) and compared to Myelomeningocele (MMC).

METHOD

This was a retrospective study of all successive patients with postnatal confirmation of a prenatal diagnosis of isolated LDM who were referred to a French National Reference center from 2014 to 2023 compared with MMC cases. Postnatal evaluation at 36 months of both dysraphisms comprised standardized multidisciplinary evaluations.

RESULTS

Of the 245 fetuses referred with suspected MMC, 19 were prenatally diagnosed with LDM. Nine children reached 36 (± 4) months of age. All were walking. Two required clean intermittent catheterization (CIC) and three required laxatives. Sphincter functions seem to be more dysfunctional in the case of sacral LDM. None were reported to have a ventricular shunt nor having neurodevelopment impairment. The LDM children differed from the MMC children in all functions with significantly more asymptomatic children in the LDM group (LDM: 5/9 vs. MMC: 0/12, p < 0.01), better motor (independent walking; LDM: 7/9 vs. MMC: 2/12; p < 0.01), urinary (need for CIC; LDM: 2/9 vs. MMC: 10/12; p < 0.01) and cognitive (neurodevelopmental impairment; LDM: 0/9 vs. MMC: 4/12, p = 0.10) functions.

CONCLUSION

LDM show better motor, urinary, and cognitive functions than MMC.

Can cavum septum pellucidum width and length measurements also be reliable indicators of corpus callosum measurements in normal fetuses?

OBJECTIVE

To examine the association between cavum septum pellucidum (CSP) and corpus callosum (CC) length and width measurements in mid-trimester sonographic screening in normal fetuses.

METHODS

This prospective cohort study examined 152 pregnant women who underwent mid-trimester sonographic fetal anomaly screening. CSP and CC lengths and their anterior, middle, and posterior width measurements were examined sonographically. The association between length and width measurements of both structures, gestational week and CSP ratio (length/width) were evaluated.

RESULTS

The mean CSP length was 7.96 ± 1.09 mm, and the mean middle width was 3.43 ± 0.82 mm. The mean CC length was 20 ± 3.76 mm, and the mean middle width was 3.43 ± 0.82 mm. There was a positive correlation between CSP and CC lengths (r = 0.691, p < 0.001). There was also a significant correlation between CSP and CC anterior, middle and posterior widths (anterior (r = 0.366, p < 0.001), middle (r = 0.305, p < 0.001), and posterior (r = 0.233, p = 0.004)). All CSP and CC measurements were correlated with gestational age, biparietal diameter (BPD), and head circumference (HC) (p < 0.001, for all). The CSP ratio was not related to CC dimensions (p > 0.05, for all) and also decreased with the increase in BPD and HC dimensions (r = -0.186, p = 0.022, and r = -0.174, p = 0.032; respectively).

CONCLUSION

In normal fetuses, the length and width of the CC and CSP structures developed in relation to each other, as well as to the gestational week, BPD, and HC dimensions. In addition, while the CSP ratio was not found to be associated with CC dimensions, it decreased due to the increase in BPD and HC sizes.

Prevalence of corpus callosum pathology in an unselected population. Should assessment of the corpus callosum be included in the routine 20 weeks scan?

OBJECTIVES

To determine the prevalence of abnormalities of the corpus callosum (AbnCC) in a non-selected population, to propose a systematic screening protocol for AbnCC in all populations through direct assessment, and to describe the follow-up and prognosis of all AbnCC cases diagnosed in our clinical setting.

METHODS

This was a retrospective review of the prevalence of AbnCC over 11 years. We included a sagittal assessment of the corpus callosum (CC) in the second-trimester scan. AbnCC was classified into complete agenesis of CC (ACC) and dysgenesis of CC (DCC; including small, partial agenesis, thick and with lipoma).

RESULTS

Of the 38,586 second-trimester scans performed during our screening, 43 cases of AbnCC were detected (prevalence of 0.8/1000). Of the AbnCC cases, 10 cases were identified as ACC (29.40%) and 24 as DCC (70.59%). Follow-up investigations showed that in the 43 cases with AbnCC, 76.5% had other associated ultrasound abnormalities, 26.5% had genetic abnormalities, 11.8% had other MRI abnormalities, and 25% of the children had neurodevelopmental delays (8.8% of the total), which were severe in only one case.

CONCLUSIONS

AbnCC is found in approximately 0.8/1000 of cases in an unselected population. The findings suggest that systematic and direct assessment of the CC as part of screening ultrasound in the second trimester of gestation should be recommended as a routine practice.

Effects of Mediterranean Diet or Mindfulness-Based Stress Reduction during Pregnancy on Fetal Brain Development Detected by Neurosonography: A Secondary Analysis of a Randomized Clinical Trial (IMPACT BCN)

INTRODUCTION

We investigated whether structured maternal lifestyle interventions based on Mediterranean diet or stress reduction influence fetal-infant neurodevelopment detected by detailed fetal neurosonography and Ages and Stages Questionnaires 3rd edition (ASQ) at 12 months old.

METHODS

This was a secondary analysis of a randomized clinical trial (2017-2020), including 1,221 singleton pregnancies at high risk for small-for-gestational age. Participants were randomized into three groups at 19-23 weeks' gestation: Mediterranean diet intervention, stress reduction program, or usual care. A detailed neurosonography was performed on 881 participants at mean (SD) 33.4 (1.1) weeks' gestation. Neurosonographic measurements were done offline. ASQ was performed on 276 infants at 1 year of corrected age.

RESULTS

Biparietal diameter was similar among study groups. Mediterranean diet group fetuses had deeper insula (26.80 [1.68] versus 26.63 [1.75], mm, p = 0.02) and longer corpus callosum (42.98 [2.44] versus 42.62 [2.27], mm, p = 0.04), with a lower rate of suboptimal score infants in ASQ problem-solving domain (6.2 vs. 16.3%, p = 0.03). Stress reduction group fetuses had deeper insula (26.90 [1.75] versus 26.63 [1.75], mm, p = 0.04) and lower rates of suboptimal score infants in ASQ fine motor domain (4.3 vs. 12.8%, p = 0.04), compared to usual care group fetuses.

CONCLUSION

Maternal structured intervention during pregnancy of the trial has the potential to modify offspring's neurodevelopment.

Outcome of partial agenesis of corpus callosum

BACKGROUND

The diagnosis of corpus callosum anomalies by prenatal ultrasound has improved over the last decade because of improved imaging techniques, scanning skills, and the routine implementation of transvaginal neurosonography.

OBJECTIVE

Our aim was to investigate all cases of incomplete agenesis of the corpus callosum and to report the sonographic characteristics, the associated anomalies, and the perinatal outcomes.

STUDY DESIGN

We performed a retrospective analysis of cases from January 2007 to December 2017 with corpus callosum anomalies, either referred for a second opinion or derived from the prenatal ultrasound screening program in a single tertiary referral center. Cases with complete agenesis were excluded from the analysis. Standardized investigation included a detailed fetal ultrasound including neurosonogram, fetal karyotyping (standard karyotype or array comparative genomic hybridization) and fetal magnetic resonance imaging. The pregnancy outcome was collected, and pathologic investigation in case of termination of the pregnancy or fetal or neonatal loss was compared with the prenatal findings. The pregnancy and fetal or neonatal outcomes were reported. The neurologic assessment was conducted by a pediatric neurologist using the Bayley Scales of Infant Development-II and the standardized Child Development Inventory when the Bayley investigation was unavailable.

RESULTS

Corpus callosum anomalies were diagnosed in 148 cases during the study period, 62 (41.9%) of which were excluded because of complete agenesis, and 86 fetuses had partial agenesis (58.1%). In 20 cases, partial agenesis (23.2%) was isolated, whereas 66 (76.7%) presented with different malformations among which 29 cases (43.9%) were only central nervous system lesions, 21 cases (31.8%) were non-central nervous system lesions, and 16 cases (24.3%) had a combination of central nervous system and non-central nervous system lesions. The mean gestational age at diagnosis for isolated and non-isolated cases was comparable (24.29 [standard deviation, 5.05] weeks and 24.71 [standard deviation, 5.35] weeks, respectively). Of the 86 pregnancies with partial agenesis, 46 patients opted for termination of the pregnancy. Neurologic follow-up data were available for 35 children. The overall neurologic outcome was normal in 21 of 35 children (60%); 3 of 35 (8.6%) showed mild impairment and 6 of 35 (17.1%) showed moderate impairment. The remaining 5 of 35 (14.3%) had severe impairment. The median duration of follow-up for the isolated form was 45.6 months (range, 36-52 months) and 73.3 months (range, 2-138 months) for the nonisolated form.

CONCLUSION

Partial corpus callosum agenesis should be accurately investigated by neurosonography and fetal magnetic resonance imaging to describe its morphology and the associated anomalies. Genetic anomalies are frequently present in nonisolated cases. Efforts must be taken to improve ultrasound diagnosis of partial agenesis and to confirm its isolated nature to enhance parental counseling. Although 60% of children with prenatal diagnosis of isolated agenesis have a favorable prognosis later in life, they often have mild to severe disabilities including speech disorders at school age and behavior and motor deficit disorders that can emerge at a later age.

Corpus Callosum Length and Cerebellar Vermian Height in Fetal Growth Restriction

INTRODUCTION

Growth-restricted fetuses may have changes in their neuroanatomical structures that can be detected in prenatal imaging. We aim to compare corpus callosal length (CCL) and cerebellar vermian height (CVH) measurements between fetal growth restriction (FGR) and control fetuses and to correlate them with cerebral Doppler velocimetry in growth-restricted fetuses.

METHODS

This was a prospective cohort of FGR after 20 weeks of gestation with ultrasound measurements of CCL and CVH. Control cohort was assembled from fetuses without FGR who had growth ultrasound after 20 weeks of gestation. We compared differences of CCL or CVH between FGR and controls. We also tested for the correlations of CCL and CVH with middle cerebral artery (MCA) pulsatility index (PI) and vertebral artery (VA) PI in the FGR group. CCL and CVH measurements were adjusted by head circumference (HC).

RESULTS

CCL and CVH were obtained in 68 and 55 fetuses, respectively. CCL/HC was smaller in FGR fetuses when compared to control fetuses (difference = 0.03, 95% CI: [0.02, 0.04], p < 0.001). CVH/HC was larger in FGR fetuses compared to NG fetuses (difference = 0.1, 95% CI: [-0.01, 0.02], p = < 0.001). VA PI multiples of the median were inversely correlated with CVH/HC (rho = -0.53, p = 0.007), while CCL/HC was not correlated with VA PI. Neither CCL/HC nor CVH/HC was correlated with MCA PI.

CONCLUSIONS

CCL/HC and CVH/HC measurements show differences in growth-restricted fetuses compared to a control cohort. We also found an inverse relationship between VA PI and CVH/HC. The potential use of neurosonography assessment in FGR assessment requires continued explorations.

Agreement between Fetal Brain Ultrasonography and Magnetic Resonance Imaging in the Measurements of the Corpus Callosum and Transverse Cerebellar Diameter

As the use of magnetic resonance imaging of the fetal brain has evolved, the need to understand its efficiency in the biometry of the fetal brain has broadened. This study aimed to assess the level of agreement and correlation between the two cardinal imaging methods of fetal neuroimaging, ultrasonography (US) and magnetic resonance imaging (MRI), by measuring the corpus callosum (CC) and transverse cerebellar diameter (TCD) in terms of length and percentile. Measurements of CC and TCD length and percentile were documented over a 7-year span in a tertiary referral medical center. All US and MRI examinations were performed in the customary planes and subcategorized by valid reference charts. Exclusion and inclusion criteria were set before the collection and processing of the data. A total of 156 fetuses out of 483 were included in the study. A positive, strong correlation and agreement were found (r = 0.78; ICC = 0.76) between US and MRI in TCD measurements. For CC length measurement, a moderate correlation and moderate agreement (r = 0.51; ICC = 0.49) between US and MRI was observed. TCD and CC percentiles had lower levels of correlation and agreement compared with the length variables. Our study indicates good agreement between MRI and US in the assessment of TCD measurement as a part of antenatal neuroimaging. Furthermore, while the two techniques are not always compatible, they are complementary methods.

Retrospective analysis of the prognostic factors of fetal corpus callosum dysplasia

BACKGROUND

To analyze the genetic characteristics and long-term outcomes of fetuses with dysplasia of the corpus callosum (DCC) or partial agenesis of the corpus callosum (PACC).

METHODS

A total of 42 fetuses with DCC (n = 36) or PACC (n = 6) were retrospectively analyzed from January 2016 to December 2022 at the Peking University First Hospital. The cohort was categorized into isolated (15/42, 36%) and nonisolated groups (27/42, 64%), and differences in the genetic abnormalities and long-term outcomes between the two groups were analyzed. DCC was subdivided into short CC, thin CC, and thick CC. The outcomes of the three different types of DCC were analyzed and discussed.

RESULTS

(1) Thirty-nine of the 42 cases underwent CMA (chromosomal microarray analysis) and CMA + WES (whole exome sequencing), with 13/15 cases in isolated group and 26/27 cases in nonisolated group. Only pathogenic or likely pathogenic (P/LP) variants were considered, identifying P/LP variants in 2/13 cases in isolated group and 12/26 cases in nonisolated group. There was no significant difference between the two groups (χ² = 3.566, P = 0.05897). (2) In the isolated group, 8 cases were terminated, and 7 cases were delivered. Postnatal follow-up detected 1 case of gross motor development delay one year after birth; no obvious abnormalities were found in the other six cases. In the nonisolated group, 21 cases were terminated, and 6 cases were delivered. Postnatal follow-up detected 4 cases of children with different degrees of language, motor and intelligence abnormalities; 1 case died 10 days after birth. No obvious abnormalities were observed in one case. Six cases (86%, 6/7) in the isolated group showed normal development, compared with 1 case (17%, 1/6) in the nonisolated group, with a significant difference (χ² = 6.198, P = 0.01279). (3) In DCC, the delivery rates of short CCs (18 cases), thin CCs (13 cases), and thick CCs (5 cases) were 17% (3/18), 54% (7/13), and 20% (1/5), respectively, with good outcomes observed in 0% (0/3), 71% (5/7), and 0% (0/1), respectively. P/LP variants were found in 6/17 cases of short CC, 3/12 cases of thin CC, and 2/5 cases of thick CC.

CONCLUSIONS

Fetuses with DCC or PACC combined with other structural abnormalities had a poor long-term prognosis compared with the isolated group. Patients with thin CCs had a higher probability of a good prognosis than those with short or thick CCs.

Tela-choroidea-to-anterior-cerebral-artery distance (TACAD): novel marker on color Doppler to identify fetuses with complete or partial agenesis of corpus callosum

OBJECTIVES

To assess objectively the course of the anterior cerebral artery (ACA) by measuring its distance to the tela choroidea in the midsagittal view, and to compare this distance in normal fetuses with that in those with agenesis of the corpus callosum (ACC), a condition known to be associated with an abnormal course of the ACA.

METHODS

The tela-choroidea-to-anterior-cerebral-artery distance (TACAD) was measured in the midsagittal view of the brain on color Doppler, between the anterior border of the tela choroidea and the ACA at the level of the callosal genu. Reference ranges in relation to gestational age were established in a prospective, cross-sectional study of 253 normal healthy fetuses between 19 and 36 weeks of gestation. The study group included fetuses with complete ACC (n = 28) or partial ACC (n = 18).

RESULTS

TACAD of normal fetuses showed an increase during the second half of pregnancy, with a mean value of 10.1 mm and 14.2 mm at 22 and 30 weeks of gestation, respectively. All (28/28) fetuses with complete ACC and 83% (15/18) of those with partial ACC had significantly shorter TACAD, with mean values of 3.9 mm and 6.6 mm, respectively.

CONCLUSIONS

TACAD is a measurement that is simple to obtain during fetal color Doppler neurosonography, which enables quantification of the course of the ACA and pericallosal artery. TACAD is shorter in fetuses with complete or partial ACC than in normal fetuses and provides an objective, quantifiable value, rather than merely descriptive information. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Corpus callosal reference ranges: systematic review of methodology of biometric chart construction and measurements obtained

OBJECTIVE

Adequate reference ranges of size of the corpus callosum (CC) are necessary to improve characterization of CC abnormalities and parental counseling. The objective of this study was to evaluate the methodology used in studies developing references charts for CC biometry.

METHODS

We conducted a systematic review of studies on fetal CC biometry using a set of predefined quality criteria of study design, statistical analysis and reporting methods. We included observational studies whose primary aim was to create ultrasound or magnetic resonance imaging charts for CC size in a normal population of fetuses. Studies were scored against a predefined set of independently agreed methodological criteria, and an overall quality score was given for each study.

RESULTS

Twelve studies met the inclusion criteria. Quality scores ranged between 17.4% and 95.7%. The greatest potential for bias was noted for the following items: sample selection and sample-size calculation, as only 17% of the studies were population-based and had consecutive or random recruitment of patients and with a justification of the sample size; number of measurements obtained for CC biometry, as only 17% of the studies performed more than one measurement per fetus and per scan; and description of characteristics of the study population, as only 8% of the studies clearly reported a minimum dataset of demographic characteristics.

CONCLUSIONS

Our review demonstrates substantial heterogeneity in methods and final biometric values of the fetal CC across the evaluated studies. The use of uniform methodology of the highest quality is essential in order to define a 'short' CC and provide appropriate parental counseling. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Development of an Ultrasound Scoring System to Describe Brain Maturation in Preterm Infants

BACKGROUND AND PURPOSE

Cerebral maturation in preterm infants predominantly occurs postnatally, necessitating the development of objective bedside markers to monitor this process. This study aimed to develop a straightforward objective Ultrasound Score of Brain Development to assess cortical development in preterm infants.

MATERIALS AND METHODS

A total of 344 serial ultrasound examinations from 94 preterm infants born at ≤ 32 weeks of gestation were analyzed to identify brain structures suitable for a scoring system.

RESULTS

Among 11 candidate structures, 3 cerebral landmarks were selected due to their correlation with gestational age: the interopercular opening (P < .001), the height of the insular cortex (P < .001), and the depth of the cingulate sulcus (P < .001). These structures can be easily visualized in a single midcoronal view in the plane through the third ventricle and the foramina of Monro. A score point from 0 to 2 was assigned to each measurement, culminating in a total score ranging from 0 to 6. The Ultrasound Score of Brain Development correlated significantly with gestational age (P < .001).

CONCLUSIONS

The proposed Ultrasound Score of Brain Development has the potential for application as an objective indicator of brain maturation in correlation with gestational age, circumventing the need to rely on individual growth trajectories and percentiles for each specific structure.

Spectrum of brain malformations in fetuses with mild tubulinopathy

OBJECTIVE

To report on a large cohort of fetuses with mild forms of tubulinopathy and to define prenatal ultrasound and magnetic resonance imaging (MRI) features that can facilitate prenatal diagnosis.

METHODS

This was a retrospective multicenter study of fetuses diagnosed between January 2007 and February 2022 with a mild tubulinopathy (without lissencephaly or microlissencephaly). We collected and reviewed brain imaging and genetic data, and defined major criteria as findings observed in ≥ 70% of the patients and minor criteria as those observed in ≥ 50% but < 70% of the patients.

RESULTS

Our cohort included 34 fetuses. The mean gestational age at ultrasound screening, when suspicion of a central nervous system anomaly was first raised, was 24.2 (range, 17-33) weeks. Callosal anomalies (n = 19 (56%)) and abnormal ventricles (n = 18 (53%)) were the main reasons for referral. The mean gestational age at neurosonography was 28.3 (range, 23-34) weeks and that at MRI was 30.2 (range, 24-35) weeks. Major ultrasound criteria were midline distortion, ventricular asymmetry, dysmorphic and/or dilated frontal horn(s) and abnormal sulcation. Minor ultrasound criteria were distortion of the cavum septi pellucidi, abnormal corpus callosum, absent or asymmetric olfactory sulci, ventriculomegaly and basal ganglia dysmorphism. Major MRI criteria were midline distortion, distortion of the cavum septi pellucidi, ventricular asymmetry, dilatation (generally unilateral) and/or distortion, dysmorphic and/or dilated frontal horn(s) and abnormal sulcation (mainly dysgyria). Minor MRI criteria were absent or asymmetric olfactory sulci, abnormal bulge of the pons, anteroposterior diameter of the pons ≤ 5th centile and brainstem asymmetry. A mutation was found in TUBB3 (44.1% of cases), TUBB (23.5%), TUBB2B (14.7%) or TUBA1A (17.6%). The mutation was inherited from a parent in 18/34 cases. The pregnancy was terminated in 23/34 cases.

CONCLUSIONS

Prenatal diagnosis of mild forms of tubulinopathy is possible but challenging. We have defined, in this large series of fetuses, major and minor criteria that can help identify this entity in utero. Most findings can be visualized on ultrasound. This evaluation is also important for prenatal counseling. Once a prenatal diagnosis of mild tubulinopathy is suspected, the family members should be referred for exome sequencing and MRI. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Abnormalities of the corpus callosum. Can prenatal imaging predict the genetic status? Correlations between imaging phenotype and genotype

OBJECTIVE

Recent studies have evaluated prenatal exome sequencing (pES) for abnormalities of the corpus callosum (CC). The objective of this study was to compare imaging phenotype and genotype findings.

METHOD

This multicenter retrospective study included fetuses with abnormalities of the CC between 2018 and 2020 by ultrasound and/or MRI and for which pES was performed. Abnormalities of the CC were classified as complete (cACC) or partial (pACC) agenesis of the CC, short CC (sCC), callosal dysgenesis (CD), interhemispheric cyst (IHC), or pericallosal lipoma (PL), isolated or not. Only pathogenic (class 5) or likely pathogenic (class 4) (P/LP) variants were considered.

RESULTS

113 fetuses were included. pES identified P/LP variants for 3/29 isolated cACC, 3/19 isolated pACC, 0/10 isolated sCC, 5/10 isolated CD, 5/13 non-isolated cACC, 3/6 non-isolated pACC, 8/11 non-isolated CD and 0/12 isolated IHC and PL. Associated cerebellar abnormalities were significantly associated with P/LP variants (OR = 7.312, p = 0.027). No correlation was found between phenotype and genotype, except for fetuses with a tubulinopathy and an MTOR pathogenic variant.

CONCLUSIONS

P/LP variants were more frequent in CD and in non-isolated abnormalities of the CC. No such variants were detected for fetuses with isolated sCC, IHC and PL.

Early Fetal Corpus Callosum: Demonstrating Normal Growth and Detecting Pathologies in Early Pregnancy

BACKGROUND AND PURPOSE

A malformed corpus callosum carries a risk for abnormal neurodevelopment. The advent of high-frequency transducers offers the opportunity to assess corpus callosum development in early pregnancy. The aim of the study was to construct a reference chart of the fetal corpus callosum length on ultrasound between 13 and 19 weeks of gestation and to prospectively examine growth patterns in pathologic cases.

MATERIALS AND METHODS

We performed a prospective cross-sectional study between 2020 and 2022 in well-dated, low-risk, singleton pregnancies between 13 and 19 weeks of gestation. A standardized image was obtained in the midsagittal plane. Imaging criteria were used as a confirmation of the early corpus callosum. Measurements were taken by 4 trained sonographers. Intra- and interobserver variability was assessed. Corpus callosum length in centiles were calculated for each gestational week.

RESULTS

One hundred eighty-seven fetuses were included in the study. All cases met inclusion criteria. At 13 weeks of gestation, the margins of the early corpus callosum were sufficiently clear to be measured in 80% (20/25) of fetuses. A cubic polynomial regression model best described the correlation between corpus length and gestational age. The correlation coefficient (r 2) was 0.929 (P < .001). Intra- and interobserver variability had high interclass correlation coefficients (>0.99). Presented is the earliest published case of agenesis of corpus callosum and a case of dysgenetic corpus callosum in Rubinstein-Taybi syndrome.

CONCLUSIONS

Provided is a nomogram of the early fetal corpus callosum. Applying imaging criteria helped to identify a case of complete agenesis of the corpus callosum as early as 14 weeks.

Reference Ranges for Corpus Callosum and Cavum Septi Pellucidi Biometry on Prenatal Ultrasound: Systematic Review and Meta-Analysis

We conducted a systematic review and meta-analysis of published nomograms for fetal corpus callosum and cavum septi pellucid biometry. A structured literature search was conducted to identify studies that reported normal measurements of the fetal corpus callosum and cavum septi pellucidi. Random effects metaanalysis was used to calculate normal ranges, and reference curves are provided. The quality assessment demonstrated that there was generally poor reporting regarding maternal characteristics and neonatal outcomes. Our findings emphasize that standardization of research protocols and publishing criteria for normal biometric ranges is needed.

Fetal corpus callosum abnormalities: Ultrasound and magnetic resonance imaging role

The corpus callosum (CC) is the major interhemispheric commissure and its abnormalities include agenesis, hypoplasia, and hyperplasia. The CC anomalies are typically related to other central nervous system (CNS) or extra-CNS malformations. The antenatal diagnosis of complete CC agenesis is easy after mid-trimester by ultrasound (US) even in the axial plane. The non-visualization of cavum septum pellucidum and colpocephaly are critical signs in the axial view. More subtle findings (i.e., hypoplasia and partial agenesis) might also be recognized antenatally. In this review, the focus was given on the prenatal diagnosis of CC abnormalities in US and magnetic resonance imaging.

Standard values for MRI brain biometry throughout the first year of life

BACKGROUND

Brain structures in the infant brain are investigated reliably using cranial magnetic resonance imaging. However, the lack of quantitative standard values for various brain regions results in data interpretation that is often subjective or based on small patient cohorts. The aim of this study was to create simple linear measurements to assess brain structures in infancy.

METHODS

We assessed cranial magnetic resonance imaging sessions of 131 children without intracerebral pathology retrospectively for size of various brain structures throughout the first year of life.

RESULTS

Standard values for the size and the growth rate of 14 brain structures including lateral ventricles, frontal subarachnoid space, pons, medulla oblongata, cerebellar vermis, pituitary gland, optical nerve, corpus callosum and the tegmentovermian angle were defined.

CONCLUSION

Our study offers reference values for the biometric assessment of the infant brain. Especially in children with multiple brain malformations, it is essential to know the normal absolute and relative size of brain structures.

Methodological Quality of Fetal Brain Structure Charts for Screening Examination and Targeted Neurosonography: A Systematic Review

INTRODUCTION

Several fetal brain charts have been published in the literature and are commonly used in the daily clinical practice. However, the methodological quality of these charts has not been critically appraised.

MATERIAL AND METHODS

MEDLINE, EMBASE, CINAHL, and the Web of Science databases were searched electronically up to December 31, 2020. The primary outcome was to evaluate the methodology of the studies assessing the growth of fetal brain structures throughout gestation. A list of 28 methodological quality criteria divided into three domains according to "study design," "statistical and reporting methods," and "specific relevant neurosonography aspects" was developed in order to assess the methodological appropriateness of the included studies. The overall quality score was defined as the sum of low risk of bias marks, with the range of possible scores being 0-28. This quality assessment was applied to each individual study reporting reference ranges for fetal brain structures. Furthermore, we performed a subgroup analysis according to the different brain structures (ventricular and periventricular, fore-brain and midbrain cerebral and posterior fossa).

RESULTS

Sixty studies were included in the systematic review. The overall mean quality score of the studies included in this review was 51.3%. When focusing on each of the assessed domains, the mean quality score was 53.7% for "study design," 54.2% for "statistical and reporting methods," and 38.6% for "specific relevant neurosonography aspects." The sample size calculation, the correlation with a postnatal imaging evaluation, and the whole fetal brain assessment were the items at the highest risk of bias for each domain assessed, respectively. The subgroup analysis according to different anatomical location showed the lowest quality score for ventricular and periventricular structures and the highest for cortical structures.

CONCLUSIONS

Most previously published studies reporting fetal brain charts suffer from poor methodology and are at high risk of biases, mostly when focusing on neurosonography issues. Further prospective longitudinal studies aiming at constructing specific growth charts for fetal brain structures should follow rigorous methodology to minimize the risk of biases, guarantee higher levels of reproducibility, and improve the standard of care.

Prenatal diagnosis of a likely pathogenic variant in ZBTB18: Natural evolution of fetal phenotype including the long bones and corpus callosum

Pathogenic variants in ZBTB18 gene have been described only postnatally with a variable phenotypic spectrum that includes intellectual disability, microcephaly, hypotonia, poor growth, corpus callosum abnormalities, seizures, and dysmorphic facial features. These features overlap with the phenotype of 1q43-q44 deletion syndrome (OMIM #612337). There are several genes within the 1q43-q44 deletion region, and ZBTB18 is of particular interest due to its known involvement in neuronal differentiation and migration. We describe here a fetus presenting with an intrauterine growth restriction, diminished long bones growth, single umbilical artery, and a short corpus callosum. On mid pregnancy ultrasound, all biometric parameters including the corpus callosum were relatively small but still within the normal range. Only a targeted follow-up during the third trimester, including neurosonographic and MRI exams, revealed the full extent of the malformation, leading to amniocentesis and a genetic workup that led to the identification of a de novo likely pathogenic variant in ZBTB18 gene. This is the first description of the evolving phenotype of a ZBTB18-related disorder in a fetus, which emphasizes the challenging diagnosis of subtle findings, that mandates a high level of clinical suspicion and a targeted follow-up throughout pregnancy.

Hypoplasia of the Corpus Callosum: A Single Center Experience and a Concise Literature Review

AimCorpus callosum hypoplasia is described as a fully formed corpus callosum with reduced thickness. Our purpose is to evaluate the current knowledge about this anomaly including it's effect on the neurodevelopmental outcome and to report our single center experience. Methods: PubMed, Medline and reference lists were searched using combinations of these terms: "Hypoplasia of corpus callosum and prenatal diagnosis" and "neurodevelopmental outcome". Results: Eleven studies were included, with a final population of 48 patients (45 cases from literature plus 3 of our own cases). Hypoplasia of the corpus callosum was detected by ultrasound scan alone in 77% of cases: magnetic resonance confirmed the ultrasound suspicion in the remaining 23% of cases. Isolated form was detected in 31% cases. Adverse fetal outcomes occurred in 62% of cases, while 38% of cases were born alive. The neurodevelopmental outcome was found to be normal in 33% of cases. Conclusion: Antenatal detection of corpus callosum hypoplasia remains challenging. Counseling is difficult because neurodevelopmental outcomes are variable.

A case of corpus callosum dysplasia with different development of the corpus callosum in the right and left brain hemispheres

The corpus callosum (CC) is a thick band of nerve fibers that divides the cerebral cortex lobes into the left and right hemispheres. Prenatal diagnosis of corpus callosum agenesis (partial/total) has been described frequently in the literature. In this case report, a case of corpus callosum dysplasia with different development of the halves of the corpus callosum in the right and left brain hemispheres, which was not previously discussed in the literature, will be described. Whenever we have any doubts about CC, axial, coronal, and sagittal scans of the fetal brain should be performed with TVUSG (transvaginal ultrasonography) or TAUSG (transabdominal ultrasonography) according to the position of the fetal head, and both length and thickness should be measured.

The Myelic Limited Dorsal Malformation: Prenatal Ultrasonographic Characteristics of an Intermediate Form of Dysraphism

OBJECTIVES

The aim of the study was to report a subtype of dysraphism designated as myelic limited dorsal malformation (MyeLDM) and to describe its characteristics at prenatal ultrasound (US).

METHODS

It was a retrospective study from 2014 to 2020 based on second-line US evaluation of patients referred to our institution for myelomeningocele (MMC). Magnetic resonance imaging and acetylcholine esterase evaluation in the amniotic fluid were also offered. Major and minor criteria for open and closed dysraphism were defined and recorded for each patient. Patients were included as MyeLDM when both criteria of closed and open dysraphism were observed in the same fetus. Correlations were obtained with the postpartum data.

RESULTS

Twenty patients fulfilled the inclusion criteria, some of them being very close to MMC, others very close to limited dorsal myeloschisis (LDM), and others lying in between. There were 13 live-born neonates and 7 terminations of pregnancy. Correlations between prenatal and postpartum data were overall very good.

CONCLUSION

Our series describe the ultrasonographic characteristics of an intermediate type of dysraphism and suggest that there is a continuum between MMC and LDM with numerous possibilities of hybrid forms (MyeLDM) sharing characteristics of both open and closed dysraphisms.

Single-direction diffusion-weighted imaging may be a simple complementary sequence for evaluating fetal corpus callosum

OBJECTIVES

To explore the feasibility of single-direction diffusion-weighted imaging (DWI) for assessing the fetal corpus callosum (CC).

METHODS

This prospective study included 67 fetuses with normal CC and 35 fetuses suspected with agenesis of the corpus callosum (ACC). The MR protocols included HASTE, TrueFISP, and single-direction DWI. Two radiologists independently evaluated the optimal visibility and the contrast ratio (CR) of the normal fetal CC. The Chi-squared test or Fisher's exact test was used to compare the proportions of "good" visibility (score ≥ 3, and the CC was almost/entirely visible) between single-direction DWI and HASTE/TrueFISP. The CR difference between single-direction DWI and HASTE/TrueFISP was detected using the paired t-test. The diagnostic accuracies were determined by comparison with postnatal imaging. In fetuses suspected of ACC, we measured and compared the length and area of the mid-sagittal CC in the single-direction DWI images.

RESULTS

The proportion of "good" visibility in single-direction DWI was higher than that in HASTE/TrueFISP, with p < 0.0001. The mean CR from single-direction DWI was also higher than that of TrueFISP and HASTE (both with p < 0.0001). The diagnostic accuracy of the single-direction DWI combined with HASTE/TrueFisp (97.1%, 34/35) was higher than that of the Haste/TrueFISP (74.3%, 26/35) (p = 0.013). The length and area of the PACC (p < 0.001, p = 0.001, respectively) and HCC (p < 0.001, p = 0.018, respectively) groups were significantly lower than those of the normal group.

CONCLUSIONS

The single-direction DWI is feasible in displaying fetal CC and can be a complementary sequence in diagnosing ACC.

KEY POINTS

• We suggest a simple method for the display of the fetal CC. • The optimal visibility and contrast ratio from single-direction DWI were higher than those from HASTE and TrueFISP. • The diagnostic accuracy of the single-direction DWI combined with HASTE/TrueFISP sequences (97.1%, 34/35) was higher than that of the Haste/TrueFISP (74.3%, 26/35).

Fetal neurosonography detects differences in cortical development and corpus callosum in late-onset small fetuses

OBJECTIVE

To explore whether neurosonography can detect differences in cortical development and corpus callosal length in late-onset small fetuses subclassified into small-for-gestational age (SGA) or growth restricted (FGR).

METHODS

This was a prospective cohort study in singleton pregnancies, including normally grown fetuses (birth weight between the 10^th and 90^th centiles) and late-onset small fetuses (estimated fetal weight < 10^th centile, diagnosed after 32 weeks of gestation and confirmed by birth weight < 10^th centile). Small fetuses were subclassified into SGA (birth weight between the 3^rd and 9^th centiles and normal fetoplacental Doppler) and FGR (birth weight < 3^rd centile and/or abnormal cerebroplacental ratio and/or abnormal uterine artery Doppler). Neurosonography was performed at 33 ± 1 weeks of gestation to assess the depth of the insula, Sylvian fissure and parieto-occipital sulcus in the axial views and corpus callosal length in the midsagittal plane. Measurements were performed offline using Alma Workstation software and were adjusted by biparietal diameter or cephalic index. Linear regression analysis was used to assess the association between the neurosonographic variables and study group, adjusting for confounding factors such as gender, gestational age at neurosonography, nulliparity and pre-eclampsia.

RESULTS

In total, 318 fetuses were included, of which 97 were normally grown and 221 were late-onset small fetuses that were further subdivided into late-onset SGA (n = 67) or late-onset FGR (n = 154). Compared to controls, both SGA and FGR cases showed significantly increased insular depth adjusted for biparietal diameter (median (interquartile range), controls 0.329 (0.312-0.342) vs SGA 0.339 (0.321-0.347) vs FGR 0.336 (0.325-0.349); P = 0.006). A linear tendency to reduced Sylvian fissure depth adjusted for biparietal diameter was also observed across the study groups (mean ± SD, controls 0.148 ± 0.021 vs SGA 0.142 ± 0.025 vs FGR 0.139 ± 0.022; P = 0.003). However, differences were significant only between the FGR and control groups. Corpus callosal length adjusted for cephalic index was significantly reduced in FGR cases compared with both controls and SGA cases, while there was no difference between SGA cases and controls (median (interquartile range), controls 0.500 (0.478-0.531) vs SGA 0.502 (0.487-0.526) vs FGR 0.475 (0.447-0.508); P = 0.005). No differences were found in parieto-occipital sulcus depth between the three study groups.

CONCLUSION

Neurosonography seems to be a sensitive tool to detect subtle structural differences in brain development in late-onset small fetuses. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal Imaging Features and Postnatal Outcome of Short Corpus Callosum: A Series of 42 Cases

OBJECTIVES

Our goal was to provide a better understanding of isolated short corpus callosum (SCC) regarding prenatal diagnosis and postnatal outcome.

METHODS

We retrospectively reviewed prenatal and postnatal imaging, clinical, and biological data from 42 cases with isolated SCC.

RESULTS

Prenatal imaging showed SCC in all cases (n = 42). SCC was limited to rostrum and/or genu and/or splenium in 21 cases, involved body in 16 cases, and was more extensive in 5 cases. Indirect imaging features included typical buffalo horn ventricles (n = 14), septal dysmorphism (n = 14), parallel lateral ventricles (n = 12), and ventriculomegaly (n = 4), as well as atypical features in 5 cases. SCC was associated with interhemispheric cysts and pericallosal lipomas in 3 and 6 cases, respectively. Aneuploidy was found in 2 cases. Normal psychomotor development, mild developmental disorders, and global developmental delay were found in 70, 15, and 15% of our cases, respectively.

CONCLUSIONS

SCC should be investigated to look for pericallosal lipoma and typical versus atypical indirect features of corpus callosum agenesis (CCA). Prenatal counselling should be guided by imaging as well as clinical and genetic context. Outcome of patients with SCC was similar to the one presenting with complete CCA.

Comparison between Two-Dimensional and Three-Dimensional Assessments of the Fetal Corpus Callosum: Reproducibility of Measurements and Acquisition Time

The objective of this article was to study the reproducibility and reliability of the fetal corpus callosum measurements between two-dimensional (2D) and three-dimensional (3D) acquisitions. This prospective study enrolled 475 fetuses, monitored between 18 and 38 weeks of gestation by two operators. Starting from a transcerebellar axial plane, 3D and 2D mid-sagittal views of the corpus callosum were obtained. Measurements of length and thickness were performed and underwent quality control by independent reviewers. The acquisition time of the two methods was measured. Means, differences, and linear correlations were analyzed using t-test, regression and Pearson's correlation coefficients, and Bland–Altman's plots. This analysis was performed for each operator to test the interobserver reproducibility. Among the 432 cases measured using both methods, 380 (88%) were validated by quality control. The mean corpus callosum length and thickness were essentially the same using 2D and 3D measurements (2D: 33.8 ± 8.7 vs. 3D: 33.7 ± 8.7 mm, 2D: 2.2 ± 0.4 vs. 3D: 2.2 ± 0.4 mm, respectively; mean ± standard deviation [SD]). Linear regression coefficients and Pearson's coefficients were similar for length (2D: 0.8283 and 0.9191 vs. 3D: 0.8271 and 0.9095), but slightly different regarding thickness (2D: 0.6775 and 0.8231 vs. 3D: 0.5831 and 0.7636). Differences between 2D and 3D measurements, considering Bland–Altman's plots and correlated with gestational age, were acceptable (2D: 0.097 ± 0.559 mm, 3D: 0.004 ± 0.111 mm). The acquisition time required was significantly lower for 3D acquisitions (3D: 25.2 ± 14.5 seconds vs. 2D: 35.1 ± 19.4 seconds, p < 0.01). Linear regression and Pearson's coefficients for the measurements of corpus callosum length and thickness using 2D or 3D acquisitions did not differ between the operators. This study confirmed good reproducibility of corpus callosum assessment by transabdominal 3D acquisitions. The good feasibility in routine scans may lead to better screening for callosal dysgenesis.

New Molecular Players in the Development of Callosal Projections

Cortical development in humans is a long and ongoing process that continuously modifies the neural circuitry into adolescence. This is well represented by the dynamic maturation of the corpus callosum, the largest white matter tract in the brain. Callosal projection neurons whose long-range axons form the main component of the corpus callosum are evolved relatively recently with a substantial, disproportionate increase in numbers in humans. Though the anatomy of the corpus callosum and cellular processes in its development have been intensively studied by experts in a variety of fields over several decades, the whole picture of its development, in particular, the molecular controls over the development of callosal projections, still has many missing pieces. This review highlights the most recent progress on the understanding of corpus callosum formation with a special emphasis on the novel molecular players in the development of axonal projections in the corpus callosum.

Ultrasound and Magnetic Resonance Imaging of Agenesis of the Corpus Callosum in Fetuses: Frontal Horns and Cavum Septi Pellucidi Are Clues to Earlier Diagnosis

OBJECTIVES

We hypothesized that: (1) fetal frontal horn (FH) morphology and their proximity to the cavum septi pellucidi (CSP) can assist in suspecting complete agenesis of the corpus callosum (cACC) and partial agenesis of the corpus callosum (pACC) earlier than known indirect ultrasound (US) findings; (2) FHs assist in differentiating a true CSP from a pseudocavum; and (3) magnetic resonance imaging (MRI) is useful in learning FH morphology and pseudocavum etiology.

METHODS

Thirty-two patients with cACC and 9 with pACC were identified on an Institutional Review Board-approved retrospective review. Of the 41 cases, 40 had prenatal US, and 21 had prenatal MRI; 17 had follow-up neonatal US, and 14 had follow-up neonatal MRI. Variables evaluated retrospectively were the presence of a CSP or a pseudocavum, ventricle size and shape, and FH shape (comma, trident, parallel, golf club, enlarged, or fused). Displacement between the inferior edge of the FH and the midline or cavum/pseudocavum was measured.

RESULTS

Fetal FHs had an abnormal shape in 77% ≤20 weeks' gestation, 86% ≤24 weeks, and 90% >24 weeks. Frontal horns were laterally displaced greater than 2 mm in 85% ≤20 weeks, 91% ≤24 weeks, and 95% >24 weeks. The CSP was absent in 100% of cACC cases and 78% of pACC cases, and a pseudocavum was present in 88% of cACC cases and 78% of pACC cases across gestation. Magnetic resonance imaging confirmed US pseudocavums to be focal interhemispheric fluid or an elevated/dilated third ventricle.

CONCLUSIONS

Frontal horns assist in assessing ACC ≤24 weeks and throughout gestation. Pseudocavums, often simulating CSPs, are common in ACC. Frontal horn lateral displacement and abnormal morphology, recognized by MRI correlations, are helpful in differentiating a pseudocavum from a true CSP. A normal CSP should not be cleared on screening US unless normally shaped FHs are seen directly adjacent to it.

Short and thick corpus callosum - the thin border between a minor anatomical variant to very poor outcome

The corpus callosum (CC) is the largest commissure connecting the cerebral hemispheres. Its components are recognized sonographically at 18-20 GW and from that point forward, its growth can be assessed using nomograms for CC length and thickness according to gestational week. Prenatal diagnosis of agenesis of the CC has been reported comprehensively. On the contrary, information regarding findings as short or thick CC is very rare. Is short CC an expression of callosal dysgenesis or could it be a variant of the normal development when all its parts exist? We discuss this issue through this case report.

The early pattern of human corpus callosum development: A transvaginal 3D neurosonographic study

OBJECTIVE

To provide an in-vivo description of early corpus callosum (CC) development.

METHODS

We reviewed 3D US volumes acquired transvaginally (TVUS) through the anterior fontanelle, between 14 to 17 weeks. The following landmarks were recognized: tela-choroidea (TC), foramina of Moro, early CC and the evolving cavum septi pellucidi. The following measurements were taken: total, anterior and posterior sections, and height of the CC (referenced to the anterior TC border). All measurements were correlated to both the gestational age and the transverse cerebellar diameter (TCD).

RESULTS

Eighty nine volumes were included in the study (mean 15.1 weeks ± 0.84, TCD range, 13.1-18.4 mm) with high inter and intra observer correlation of the measurements. We found high correlation between CC length and height, and TCD. The anterior segment of the CC appear earlier than the posterior one, and growth continues bi-directionally. Initially, the posterior elongation is significantly larger than the anterior one. Association of all CC measurements with TCD remained significant when co-varying for maternal age and fetal sex.

CONCLUSIONS

imaging the fetal CC is feasible from 14 weeks by TVUS, by following the suggested insonation approach. The early CC develops bi-directionally, and the posterior elongation is more significant than the anterior one.

Linear growth of corpus callosum and cerebellar vermis in very-low-birth-weight preterm infants

BACKGROUND/PURPOSE

Impaired growth of the corpus callosum (CC) and cerebellar vermis (CV) is associated with poorer neurodevelopmental outcomes in preterm infants. However, references on the postnatal growth rate of the CC and CV by sonography are limited. The aim of this study is to assess the normal linear growth of CC and CV using a serial cranial ultrasound.

METHODS

We prospectively enrolled preterm infants with very low birth weight from September 2008 to December 2009 after excluding those with congenital anomalies or diseases affecting the brain parenchyma. Serial sonographic measurements of the CC and CV were performed according to the standard protocol. Scheduled comprehensive neurodevelopmental evaluations were performed till the corrected age of 2 years. We excluded those with significant brain damages or poor neurodevelopmental outcomes in the final analysis. The growth rate was estimated using the loess smoothing curve and linear regression analysis.

RESULTS

Among the 86 enrolled neonates, 14 with significant brain damage and 8 with poor neurodevelopmental outcomes were excluded from the final analysis. The growth rate of the CC length was 1.72 (95% confidence interval [CI]: 1.24-2.20) and 0.57 (95% CI: 0.33-0.80) mm per week before and after the postmenstrual age of 30.5 weeks, respectively. The growth rate of the CV length was 0.78 (95% CI: 0.68-0.89) mm per week.

CONCLUSION

We proposed reference values of the normal linear growth rate of the CC and CV lengths in very-low-birth-weight preterm infants using the serial cranial ultrasound.

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.

New insights in cerebral findings associated with fetal myelomeningocele: a retrospective cohort study in a single tertiary centre

OBJECTIVE

To investigate cerebral anomalies other than Chiari type 2 malformation in fetuses with myelomeningocele (MMC).

DESIGN

A retrospective cohort study in a single tertiary centre.

SETTING

A review of associated cerebral anomalies in cases with prenatal diagnosis of myelomeningocele.

POPULATION

Seventy cases of fetal myelomeningocele.

METHODS

Ultrasound and MRI images were blindly reviewed. Postnatal imaging and results of the postmortem results were also reviewed. The association between cerebral anomalies and the following ultrasound findings was measured: level of the defect, ventriculomegaly, microcephaly and fetal talipes.

MAIN OUTCOME MEASURES

A microcephaly was observed in 32/70 cases (46%) and a ventriculomegaly was observed in 39/70 cases (56%). Other cerebral anomalies were diagnosed in 47/70 (67%).

RESULTS

Other cerebral anomalies were represented by 42/70 cases with abnormal CC (60%), 8/70 cases with perinodular heterotopia (PNH; 11%), 2/70 cases with abnormal gyration (3%). MRI performed only in fetal surgery cases confirmed the ulltrasound findings in all cases and provided additional findings in two cases (PNH). Risk ratios of fetal cerebral anomalies associated with MMC did not reach significance for microcephaly, ventriculomegaly, talipes or the level of the defect There was an overall good correlation between pre- and postnatal findings with a Kappa value of 0.79 [95% CI 0.57-1] and 82% agreement.

CONCLUSION

Fetal brain anomalies other than Chiari type 2 malformation are frequently observed in fetuses with myelomeningocele, predominantly represented by CC anomalies. Whether these associated cerebral anomalies have an impact on selecting cases eligible for fetal surgery needs further evaluation.

TWEETABLE ABSTRACT

Fetal cerebral anomalies other than Chiari type 2 malformation, microcephaly, and ventriculomegaly may be associated with MMC in up to 67% of the cases.

Feasibility and agreement of including anterior-posterior complexes and landmarks of the proximal hemisphere into basic examination of the fetal brain: A prospective study

OBJECTIVE

To assess the feasibility of identifying structures included in anterior complex (AC) and posterior complex (PC), as well as a series of anatomic landmarks that could help to demonstrate the integrity of the cerebral proximal hemisphere (PH).

METHODS

This was a prospective observational multicenter study of healthy pregnant women attending routine ultrasound screening at 20 + 0 to 33 + 6 weeks' gestation. Six physicians performed transabdominal (TA) ultrasound, in order to obtain the planes required to visualize the AC, PC, and PH. Blind analysis by a nonexpert and two experts in fetal neurosonography was used to assess the structures included in each plane view.

RESULTS

In the population studied (n = 747), detection of the structure rates for AC, PC, and proximal hemisphere was of 94%, 93%, and 96%, respectively, with an agreement of 97%, 94%, and 98% when comparing an expert and a nonexpert in fetal brain examiner. Detection of structures in the proximal hemisphere was significantly higher when observed through the proximal hemisphere plane rather than the transventricular plane.

CONCLUSION

Our results suggest that inclusion of AC and PC complexes visualization, as well as real-time access to the proximal hemisphere, is feasible and could improve the prenatal detection of fetal cerebral anomalies.

A new method for evaluating short fetal corpus callosum

OBJECTIVE

Sonographic diagnosis of short corpus callosum (SCC) is based on measurement of a short for gestational age antero-posterior length of the corpus callosum (CC) in the midsagittal plane. We suggest a new method for evaluating SCC without referring to biometry tables.

METHODS

We measured the ratio between the CC length and the internal cranial occipitofrontal dimension (ICOFD) in the midsagittal plane in 399 normal fetuses at 20 + 6 to 35 + 3 weeks of gestation and in 31 fetuses with a diagnosis of a SCC and compared the mean ratio between two groups. The impact of cephalic biometric parameters, fetal presentation, and gender was assessed.

RESULTS

The ICOFD/CC length for normal pregnancies was constant throughout the pregnancy (2.35 ± 0.11). There was no correlation between the ICOFD/CC length and cephalic index, Biparietal Diameter (BPD), head circumference, fetal sex, or fetal presentation. The ratio of pregnancies with SCC was significantly higher: 3.20 ± 0.84 (P < .0001).

CONCLUSION

The ICOFD/CC length practically does not change throughout a normal pregnancy. The ratio was significantly higher in pregnancies with SCC. Measuring this ratio during fetal anatomical scan may enable rapid evaluation of the CC without the need to refer to biometry tables.

Determining gestational age using genome methylation profile: A novel approach for fetal medicine

Gestational age determination by traditional tools (last menstrual period, ultrasonography measurements and Ballard Maturational Assessment in newborns) has major limitations and therefore there is a need to find different approaches. In this study, we looked for a molecular marker that can be used to determine the accurate gestational age of the newborn. To this end, we performed reduced representation bisulfite sequencing (RRBS) on 41 cord blood and matching placenta samples from women between 25 and 40 weeks of gestation and generated an epigenetic clock based on the methylation level at different loci in the genome. We identified a set of 332 differentially methylated regions (DMRs) that undergo demethylation in late gestational age in cord blood cells and can predict the gestational age (r = -.7, P = 2E-05). Once the set of 411 DMRs that undergo de novo methylation in late gestational age was used in combination with the first set, it generated a more accurate clock (R = .77, P = 1.87E-05). We have compared gestational age determined by Ballard score assessment with our epigenetic clock and found high concordance. Taken together, this study demonstrates that DNA methylation can accurately predict gestational age and thus may serve as a good clinical predictor.

Neurodevelopmental outcome following prenatal diagnosis of a short corpus callosum

OBJECTIVE

Data regarding the neurodevelopmental outcome of fetal short corpus callosum (CC) diagnosed according to standard reference charts is scarce. The purpose of this study was to assess whether the finding is related to neurodevelopmental delay, and to examine reclassification to normal fetal CC length using CC length/EFW ratio.

METHOD

Historical prospective cohort study including pregnant women who were referred for fetal neurosonogram due to abnormal CC. Short CC was defined below the 5^th percentile according to reference charts. Twenty cases were included in the study group and compared with a control group of 59 normal cases. The patients in the study group were divided into two groups according to CC length/EFW ratio. Children's neurodevelopment was assessed using the Vineland Adaptive Behavior Scale (VABS).

RESULTS

VABS scores were within normal range in 90% of the cases. There was no significant statistical difference between the study group and the control group. In addition, there was no statistically significant difference between fetuses reclassified as normal callosal length according to CC length/EFW ratio in comparison to the control group.

CONCLUSION

The neurodevelopmental outcome of fetuses with diagnosed short CC did not differ from the neurodevelopment of normal fetuses in the control group.

Personalized charts for the fetal corpus callosum length

Objective: To personally customize the antenatal ultrasound charts for the fetal corpus callosum (CC) length. Methods: A retrospective analysis of fetal neuro-sonography scans. Cases were grouped as normal neuro-sonographic evaluation (normal) or as high risk and suspected brain anomaly (abnormal). The normal group was subcategorized according to Cignini's CC length charts. Data of fetuses with a CC length between the 5th-95th percentile served for creating new charts, describing the ratio of the CC length to the major biometric parameters as a function of gestational age (GA). Results: A total of 410 measurements were included. Of them 255 were normal and 155 abnormal. The CC length/estimated fetal weight (EFW) ratio had the strongest linear association with GA (R² = 0.929). Applying charts using this ratio to the normal group, significantly increased the percent of CC length measurements defined as normal from 84.7 to 94.5% (p < .001). Conversely, applying these charts to the abnormal group nonsignificantly decreased the number of measurement defined as normal from 89 to 83.2% (p = .137) Conclusions: The CC length/EFW ratio is strongly and linearly associated with GA. Using this personalized ratio may improve the diagnostic accuracy of CC evaluation by adjusting the CC length to the fetus natural proportions.

Variability of T1-weighted signal intensity of pericallosal lipomas in the fetus

BACKGROUND

Pericallosal lipomas are often associated with corpus callosum dysgenesis. The diagnosis of lipoma, suggested on ultrasonography, relies on the classic T1 hyperintensity on magnetic resonance imaging (MRI). However, this feature may be absent prenatally.

OBJECTIVE

Our objective was to study the changes of T1 intensity in fetal lipomas with comparison to postnatal/postmortem data and to assess the factors influencing the signal variations of pericallosal lipomas on prenatal MRI.

MATERIALS AND METHODS

Patients with callosum dysgenesis and interhemispheric hyperechogenicity suggestive of a pericallosal lipoma with available postnatal or postmortem data were included. Gestational age, lipoma size and pattern, corpus callosum size and changes in fetal fat T1 intensity were recorded. Comparison with postmortem neuropathology was available for one fetus.

RESULTS

Eleven patients with callosum dysgenesis and pericallosal lipomas (seven curvilinear and four tubulonodular) were included. All MRI scans were performed in the third trimester. Curvilinear lipomas were thinner and six cases were associated with prenatal T1 iso-intensity. Typical T1 hyperintensity appeared on postnatal MRI only. All tubulonodular lipomas were much larger and showed prenatal T1 hyperintensity. In two patients, the lipoma increased in size on postnatal MRI.

CONCLUSION

The type and size of a lipoma influence T1 prenatal intensity. Absence of T1 intensity was observed in curvilinear lipomas only. Curvilinear lipomas are much thinner. Changes in T1 intensity may also be related to fat maturation within the lipoma and, subsequently, to gestational age. In the case of callosum dysgenesis, absence of prenatal T1 pericallosal hyperintensity should not exclude the diagnosis of pericallosal lipoma.

Ultrasound imaging for identification of cerebral damage in congenital Zika virus syndrome: a case series

BACKGROUND

Zika virus is a novel teratogenic agent associated with cerebral anomalies. Because of the challenges associated with assessment of antenatal diagnosis and prognosis in fetuses, screening for other congenital infections mostly relies on ultrasound. We aimed to assess whether a similar approach might be adequate for Zika virus congenital syndrome provided that early markers of infection and adequate timing for screening are established.

METHODS

For this case series we reviewed all pregnant women who had a laboratory-confirmed Zika virus infection in their first trimester or early second trimester and abnormal fetal ultrasound findings who were managed at the Pluridisciplinary Center for Prenatal Diagnosis of Martinique during the Zika virus epidemic (Jan 1, 2016, to Nov 10, 2016) in Martinique, a French Caribbean island. Ultrasound imaging was done with GE Healthcare Voluson E10 and E8 machines with abdominal and vaginal probes.

FINDINGS

We analysed 14 cases of pregnant women with confirmed Zika virus infection and fetal abnormalities of the brain, and 31 ultrasound imaging results. Between 16 and 20 weeks of gestation, four (33%) of 12 fetuses had an abnormal ultrasound examination. Anomalies were detected in nine (90%) of the ten fetuses from whom ultrasound images were obtained between 20 and 24 weeks of gestation. All five remaining fetuses at 24-28 weeks of gestation, and all four after 28 weeks, had severe anomalies. Major anomalies identified were ventriculomegaly (12 fetuses, 86%), cortical atrophy (11, 79%), calcifications (ten, 71%; particularly located at the corticosubcortical junction), and anomalies of the corpus callosum (ten, 71%). Prenatal assessment of head circumference measurement by imaging was not an effective screening tool for congenital Zika virus infection, with microcephaly only identified in nine (64%) fetuses.

INTERPRETATION

Ultrasound monitoring appears to be a good screening strategy to monitor Zika virus-exposed pregnancies. Public health efforts should focus on scanning at 22-26 weeks of gestation. Identification of ventriculomegaly, cortical atrophy, calcifications, and anomalies of the corpus callosum should prompt laboratory screening for Zika virus.

FUNDING

None.

What Is the Rate of Incomplete Fetal Anatomic Surveys During a Second-Trimester Scan? Retrospective Observational Study of 4000 Nonobese Pregnant Women

OBJECTIVES

The purpose of this study was to estimate the rate of incomplete fetal anatomic surveys during a second-trimester scan due to an unfavorable fetal position in a nonobese population.

METHODS

All pregnant women who came to the Altamedica Fetal-Maternal Medical Center, a specialized center for prenatal diagnosis, for a routine second-trimester scan between January 2012 and April 2013 were retrospectively included in the analysis. Patients with a body mass index higher than 30.0 kg/m(2) or anterior fibroids larger than 5 cm were not included in the study.

RESULTS

Of 4000 pregnant women admitted for a second-trimester scan, 169 (4.2%) came back within 2 weeks to complete the examination because of an unfavorable fetal position. In particular, 104 (2.6%) needed visualization of only 1 view, and 65 (1.6%) needed more than 1 view. The most difficult organ to visualize was the corpus callosum, in 73 cases (1.8%); the face was not visualized in 69 cases (1.7%); the cerebellar vermis was not seen in 47 fetuses (1.1%); and the heart could not be completely examined in 40 fetuses (1.0%). Of the 4000 women, 169 (4.2%) had a nonexhaustive scan; 149 (3.7%) needed a second scan to complete the second-trimester survey; 14 (0.35%) needed a third scan; and 2 (0.05%) remained with a not completely exhaustive scan.

CONCLUSIONS

There is always a small percentage of incomplete fetal anatomic surveys during a second-trimester scan, which cannot be modified by the sonographer's skill or by technical sonographic innovations.