Outcome in prenatally diagnosed fetal agenesis of the corpus callosum

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.

MR insights into fetal brain development: what is normal and what is not

Fetal brain development is a complex, rapid, and multi-dimensional process that can be documented with MRI. In the second and third trimesters, there are predictable developmental changes that must be recognized and differentiated from disease. This review delves into the key biological processes that drive fetal brain development, highlights normal developmental anatomy, and provides a framework to identify pathology. We will summarize the development of the cerebral hemispheres, sulci and gyri, extra-axial and ventricular cerebrospinal fluid, and corpus callosum and illustrate the most common abnormal findings in the clinical setting.

Anomalies of the Corpus Callosum in Prenatal Ultrasound: A Narrative Review for Diagnosis and Further Counseling

The corpus callosum is the major interhemispheric tract that plays an important role in neurological function. Understanding the etiology and embryology development helps the ultrasound diagnosis for disorders of the corpus callosum and further counseling. The nonvisualization of cavum septum pellucidum or dysmorphic cavum septum pellucidum in axial view are indirect signs for beginners to diagnose complete agenesis of corpus callosum (cACC) and partial agenesis of the corpus callosum (pACC). Further coronal view, sagittal view, and fetal magnetic resonance imaging are also important for evaluation. Genetic testing plays an essential tool in anomalies of corpus callosum by revealing the underlying genetic pathophysiology, such as chromosomal anomalies and numerous monogenetic disorders in 30%-45% of ACC. Diagnosis and prediction of prognosis for hypoplasia or hyperplasia of the corpus callosum are more difficult compared to cACC and pACC because of the limited reports in the literature. However, the complex types often had poorer prognostic outcomes compared to the isolated types. Hence, it is important to evaluate and follow fetal conditions thoroughly to rule out intracranial or extracranial anomalies in other systems.

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.

Unravelling the Clinical Co-Morbidity and Risk Factors Associated with Agenesis of the Corpus Callosum

Agenesis of the Corpus Callosum (ACC) can result in multiple neurological deficits including social and behavioural issues. However, the underlying aetiology, clinical co-morbidity and the contributing risk factors remain elusive, resulting in inaccurate prognosis and delayed therapy. The main objective of this study was to comprehensively describe the epidemiology and clinical co-morbidity associated with patients diagnosed with ACC. The secondary objective was to identify the factors that contribute towards increased risk for ACC. For this, we analysed 22 years (1998-2020) of clinical data across the whole of Wales, UK collected through the Congenital Anomaly Register & Information Service (CARIS) and Public Health Wales (PHW). Our results demonstrate that complete ACC (84.1%) was the prevalent subtype, in comparison to partial ACC. Further, ventriculomegaly/hydrocephalus (26.37%) and ventricular septal defect (21.92%) were identified to be the most prevalent neural malformation (NM) and congenital heart disorder (CHD) in our cohort. Although 12.7% of subjects with ACC had both an NM and CHD, we found no significant association between them (χ² (1, n = 220) = 3.84, p = 0.33). We found socioeconomic deprivation and increased maternal age contributed towards an increased risk for ACC. To the best of our knowledge, this study for the first time defines the clinical phenotypes and the factors that contribute to ACC within the Welsh population. These findings will be of value to both patients and healthcare professionals, who may take preventative or remedial measures.

Corpus callosum size by neurosonography in fetuses with congenital heart defect and relationship with expected pattern of brain oxygen supply

OBJECTIVE

To evaluate corpus callosum (CC) size by neurosonography (NSG) in fetuses with an isolated major congenital heart defect (CHD) and explore the association of CC size with the expected pattern of in-utero oxygen supply to the brain.

METHODS

A total of 56 fetuses with postnatally confirmed isolated major CHD and 56 gestational-age-matched controls were included. Fetuses with CHD were stratified into two categories according to the main expected pattern of cerebral arterial oxygen supply: Class A, moderately to severely reduced oxygen supply (left outflow tract obstruction and transposition of the great arteries) and Class B, near normal or mildly impaired oxygenated blood supply to the brain (other CHD). Transvaginal NSG was performed at 32-36 weeks in all fetuses to evaluate CC length, CC total area and areas of CC subdivisions in the midsagittal plane.

RESULTS

CHD fetuses had a significantly smaller CC area as compared to controls (7.91 ± 1.30 vs 9.01 ± 1.44 mm² ; P < 0.001), which was more pronounced in the most posterior part of the CC. There was a significant linear trend for reduced CC total area across the three clinical groups, with CHD Class-A cases showing more prominent changes (controls, 9.01 ± 1.44 vs CHD Class B, 8.18 ± 1.21 vs CHD Class A, 7.53 ± 1.33 mm² ; P < 0.05).

CONCLUSIONS

Fetuses with major CHD had a smaller CC compared with controls, and the difference was more marked in the CHD subgroup with expected poorer brain oxygenation. Sonographic CC size could be a clinically feasible marker of abnormal white matter development in CHD. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Symptom-Related Differential Neuroimaging Biomarkers in Children with Corpus Callosum Abnormalities

We aimed to identify symptom-related neuroimaging biomarkers for patients with dysgenesis of the corpus callosum (dCC) by summarizing neurological symptoms reported in clinical evaluations and correlating them with retrospectively collected structural/diffusion brain magnetic resonance imaging (MRI) measures from 39 patients/controls (mean age 8.08 ± 3.98). Most symptoms/disorders studied were associated with CC abnormalities. Total brain (TB) volume was related to language, cognition, muscle tone, and metabolic/endocrine abnormalities. Although white matter (WM) volume was not related to symptoms studied, gray matter (GM) volume was related to cognitive, behavioral, and metabolic/endocrine disorders. Right hemisphere (RH) cortical thickness (CT) was linked to language abnormalities, while left hemisphere (LH) CT was linked to epilepsy. While RH gyrification index (GI) was not related to any symptoms studied, LH GI was uniquely related to cognitive disorders. Between patients and controls, GM volume and LH/RH CT were significantly greater in dCC patients, while WM volume and LH/RH GI were significantly greater in controls. TB volume and diffusion indices for tissue microstructures did not show differences between the groups. In summary, our brain MRI-based measures successfully revealed differential links to many symptoms. Specifically, LH GI abnormality can be a predictor for dCC patients, which is uniquely associated with the patients' symptom. In addition, patients with CC abnormalities had normal TB volume and overall tissue microstructures, with potentially deteriorated mechanisms to expand/fold the brain, indicated by GI.

Fetal US and MRI in detection of craniospinal anomalies with postnatal correlation: single-center experience

Background/aim

To reveal the contribution of magnetic resonance imaging (MRI) to ultrasound (US) in prenatal diagnosis of fetal craniospinal anomalies by retrospectively comparing the prenatal and postnatal findings.

Materials and methods

After institutional review board approval, between January 2010 and May 2020, 301 pregnant women, which had a gestational age between 19–37 weeks (mean 26.5 ± 6.1 weeks), diagnosed with cranial and spinal anomalies on fetal US and later on imaged with MRI were evaluated, and in 179 of those cases prenatal imaging findings were compared with postnatal findings.

Results

A total of 191 fetal craniospinal anomalies were detected in 179 pregnant women. MRI and US diagnosis were completely correct in 145 (75.9%) and 112 (58.6%), respectively. Diagnostic performance of MRI was significantly higher than that of the US (p < 0.05). Both prenatal MRI and US findings were concordant with postnatal diagnosis in 53% of the cases. In 28.7% cases, prenatal MRI contributed to US by either changing the wrong US diagnosis (8.9%), demonstration of additional findings (14%), or confirming the suspicious US diagnosis (5.8%).

Conclusion

Due to its high resolution and multiplanar imaging capability, fetal MRI contributes significantly to US in the correct prenatal diagnosis of craniospinal anomalies. This contribution especially is significant in neural tube defects, cortical malformations, and ischemic-hemorrhagic lesions.

Corpus callosum metrics predict severity of visuospatial and neuromotor dysfunctions in ARID1B mutations with Coffin-Siris syndrome

ARID1B mutations in Coffin-Siris syndrome are a cause of intellectual disability (0.5-1%), with various degrees of autism and agenesis of the corpus callosum (10%). Little is known regarding the cognitive and motor consequences of ARID1B mutations in humans and no link has been made between corpus callosum anomalies and visuospatial and neuromotor dysfunctions. We have investigated the visuospatial and neuromotor phenotype in eight patients with ARID1B mutations. A paramedian sagittal section of the brain MRI was selected, and corpus callosum was measured in anteroposterior length, genu and trunk width. Spearman's rank order coefficients were used to explore correlations between visuospatial and social cognitive variables and dimensions of the corpus callosum. A significant correlation between genu width size and visual cognition was observed. Retrocerebellar cysts were associated with corpus callosum anomalies. Here, we show that corpus callosum anomalies caused in ARID1B mutations may be predictive of the visuospatial and motor phenotype in Coffin-Siris syndrome.

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.

Neurodevelopmental outcomes in children with prenatally diagnosed corpus callosal abnormalities

OBJECTIVE

Although corpus callosal abnormalities are among the most common brain malformations detected prenatally, few previous studies have described the neurodevelopmental outcomes of children with this condition. The aim of our study was to evaluate the neurodevelopmental outcomes and associated clinical features of children with corpus callosal abnormalities diagnosed by prenatal ultrasonography.

METHODS

Between July 2011 and July 2016, forty-nine children with corpus callosal abnormalities were born in Asan Medical Center Children's Hospital. Neurodevelopmental assessments were conducted in 40 patients at a median age of 24.8 months using the Bayley Scales of Infant Development II or the Korean Infant and Child Development Test. Patients were categorized according to their postnatal magnetic resonance imaging (MRI) findings and accompanying anomalies. Baseline characteristics and developmental outcomes of each group were compared.

RESULTS

Isolated agenesis or hypoplasia of the corpus callosum was found in 16 (32.7%) patients, other associated central nervous system (CNS) abnormalities were found in 28 (57.1%) patients, and non-CNS abnormalities were found in 11 (22.4%) patients. Among the 40 patients who underwent developmental assessment, 18 (45.0%) showed normal development and 10 (25.0%) showed moderate-to-severe global developmental delay. Seven of the twelve (58.3%) patients with isolated corpus callosal abnormalities showed normal development. The combination of corpus callosal abnormalities with non-CNS anomalies was significantly associated with developmental delay (odds ratio 2.5, 95% confidence interval 1.6-3.9, p = 0.001). Conversely, children with isolated corpus callosal abnormalities showed relatively favorable neurodevelopmental outcomes.

CONCLUSION

Appropriate evaluation and comprehensive therapeutic approaches are strongly recommended for neonates who present with corpus callosal abnormalities combined with additional anomalies.

Learning to segment key clinical anatomical structures in fetal neurosonography informed by a region-based descriptor

We present a general framework for automatic segmentation of fetal brain structures in ultrasound images inspired by recent advances in machine learning. The approach is based on a region descriptor that characterizes the shape and local intensity context of different neurological structures without explicit models. To validate our framework, we present experiments to segment two fetal brain structures of clinical importance that have quite different ultrasonic appearances-the corpus callosum (CC) and the choroid plexus (CP). Results demonstrate that our approach achieves high region segmentation accuracy (dice coefficient: [Formula: see text] CC, [Formula: see text] CP) relative to human delineation, whereas the derived automated biometry measurement deviations are within human intra/interobserver variations. The use of our proposed method may help to standardize intracranial anatomy measurements for both the routine examination and the detection of congenital conditions in the future.

Cavum septi pellucidi (CSP) ratio: a marker for partial agenesis of the fetal corpus callosum

OBJECTIVE

While complete agenesis of the corpus callosum is often suspected on fetal ultrasound due to absence of the cavum septi pellucidi (CSP), suspicion of partial agenesis of the corpus callosum (pACC) is a challenge since the CSP is almost always present. The aim of this study was to measure the length and width of the CSP and calculate the length-to-width ratio (CSP ratio), and compare these between fetuses with pACC and normal fetuses.

METHODS

In this retrospective case-control study, the length and width of the CSP were measured in the axial plane of the fetal head, and the CSP length-to-width ratio calculated, in 323 normal fetuses and in 20 fetuses with pACC between 20 and 34 weeks' gestation. From the normal population we constructed reference ranges in relation to biparietal diameter (BPD). For all fetuses we calculated Z-scores for the CSP ratio.

RESULTS

In the normal population, the length and width of the CSP increased with increasing BPD, while the CSP ratio decreased. The CSP was short (< 5^th centile) in 85% (17/20) of fetuses with pACC and wide (> 95^th centile) in 65% (13/20). The CSP ratio was small (< 5^th centile) in 95% (19/20) of pACC fetuses, with 16/20 (80%) having a ratio below an empirical cut-off of 1.5. Analysis of Z-scores showed that fetuses with pACC had a significantly smaller CSP ratio (P < 0.0001) compared with the normal population.

CONCLUSIONS

Fetuses with a normal-sized corpus callosum have a rectangular-shaped CSP, with a CSP ratio > 1.5 in the second half of gestation. Most fetuses with pACC have an abnormally shaped, wide and short CSP, with a decreased CSP ratio. This simple ratio has the potential to identify fetuses at high risk for pACC. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Agenesis of the corpus callosum, developmental delay, autism spectrum disorder, facial dysmorphism, and posterior polymorphous corneal dystrophy associated with ZEB1 gene deletion

We report on a girl diagnosed prenatally with agenesis of the corpus callosum (ACC) on fetal ultrasound and MRI. On postnatal follow-up she was noted to have developmental delay, facial dysmorphism, autism spectrum disorder, and posterior polymorphous corneal dystrophy (PPD). Array-comparative genomic hybridization analysis (Array-CGH) showed a 2.05 Mb de novo interstitial deletion at 10p11.23p11.22. The deleted region overlaps 1 OMIM Morbid Map gene, ZEB1 (the zinc finger E-box binding homeobox transcription factor 1), previously associated with posterior polymorphous corneal dystrophy type 3 (PPCD3). To our best knowledge this is the first reported case with a deletion of the ZEB1 gene in an individual with ACC and PPD, showing that the haploinsufficiency of the ZEB1 is likely the cause of our patient's phenotype.

Role of fetal MRI in the evaluation of isolated and non-isolated corpus callosum dysgenesis: results of a cross-sectional study

PURPOSE

The aims of this study were to characterize isolated and non-isolated forms of corpus callosum dysgenesis (CCD) at fetal magnetic resonance imaging (MRI) and to identify early predictors of associated anomalies.

METHODS

We retrospectively analyzed 104 fetuses with CCD undergoing MRI between 2006 and 2016. Corpus callosum, cavum septi pellucidi, biometry, presence of ventriculomegaly, gyration anomalies, cranio-encephalic abnormalities and body malformations were evaluated. Results of genetic tests were also recorded.

RESULTS

At MRI, isolated CCD was 26.9%, the rest being associated to other abnormalities. In the isolated group, median gestational age at MRI was lower in complete agenesis than in hypoplasia (22 vs 28 weeks). In the group with additional findings, cortical dysplasia was the most frequently associated feature (P = 0.008), with a more frequent occurrence in complete agenesis (70%) versus other forms; mesial frontal lobes were more often involved than other cortical regions (P = 0.006), with polymicrogyria as the most frequent cortical malformation (40%). Multivariate analysis confirmed the association between complete agenesis and cortical dysplasia (odds ratio = 7.29, 95% confidence interval 1.51-35.21).

CONCLUSIONS

CCD is often complicated by other intra-cranial and extra-cranial findings (cortical dysplasias as the most prevalent) that significantly affect the postnatal prognosis. The present study showed CCD with associated anomalies as more frequent than isolated (73.1%). In isolated forms, severe ventriculomegaly was a reliable herald of future appearance of associated features. © 2016 John Wiley & Sons, Ltd.

Outcomes Associated With Isolated Agenesis of the Corpus Callosum: A Meta-analysis

CONTEXT

Antenatal counseling in cases of agenesis of the corpus callosum (ACC) is challenging.

OBJECTIVES

To ascertain the outcome in fetuses with isolated complete ACC and partial ACC.

DATA SOURCES

Medline, Embase, CINAHL, and Cochrane databases.

STUDY SELECTION

Studies reporting a prenatal diagnosis of ACC. The outcomes observed were: chromosomal abnormalities at standard karyotype and chromosomal microarray (CMA) analysis, additional anomalies detected only at prenatal MRI and at postnatal imaging or clinical evaluation, concordance between prenatal and postnatal diagnosis and neurodevelopmental outcome.

DATA EXTRACTION

Meta-analyses of proportions were used to combine data.

RESULTS

Twenty-seven studies were included. In cACC, chromosomal anomalies occurred in 4.81% (95% confidence interval [CI], 2.2-8.4) of the cases. Gross and fine motor control were abnormal in 4.40% (95% CI, 0.6-11.3) and 10.98% (95% CI, 4.1-20.6) of the cases, respectively, whereas 6.80% (95% CI, 1.7-14.9) presented with epilepsy. Abnormal cognitive status occurred in 15.16% (95% CI, 6.9-25.9) of cases. In partial ACC, the rate of chromosomal anomalies was 7.45% (95% CI, 2.0-15.9). Fine motor control was affected in 11.74% (95% CI, 0.9-32.1) of the cases, and 16.11% (95% CI, 2.5-38.2) presented with epilepsy. Cognitive status was affected in 17.25% (95% CI, 3.0-39.7) of cases.

LIMITATIONS

Different neurodevelopmental tools and time of follow-up of the included studies.

CONCLUSIONS

Children wih a prenatal diagnosis of isolated ACC show several degrees of impairment in motor control, coordination, language, and cognitive status. However, in view of the large heterogeneity in outcomes measures, time at follow-up, and neurodevelopmental tools used, large prospective studies are needed to ascertain the actual occurrence of neuropsychological morbidity of children with isolated ACC.

Agenesis of the corpus callosum. An autopsy study in fetuses

Agenesis of the corpus callosum is currently diagnosed prenatally with ultrasound and MRI. While the diagnostic aspects of callosal defects are widely addressed, anatomo-histological data from fetal autopsies are sparse. Callosal defects were present in 50 fetal autopsies. Four distinct groups of complete, partial, hypoplastic, and mixed defects were determined by the gross and histologic details of the corpus callosum. These details helped to rule out other midline defects such as holoprosencephaly. Additional autopsy findings enabled specific diagnoses and suggested etiopathogeneses. Hypoplastic and mixed defects were associated with more abnormalities of the cerebral hemispheres and internal organs. The four groups did not differ according to gender, external dysmorphism, or cerebellar and brainstem anomalies. Defects were classified as syndromic (68 %), encephaloclastic (8 %), undetermined (14 %), or isolated (10 %) based on the autopsy findings. Isolated agenesis of the corpus callosum was diagnosed in only 10 % of the cases in this series, compared to higher numbers diagnosed by prenatal ultrasonography and MRI. Therefore, the autopsy, through its detailed, careful evaluation of external, as well as gross and histological internal features, can elucidate the etiopathogenesis of agenesis of the corpus callosum and suggest specific diagnoses which cannot be ascertained by prenatal imaging.

Morphometric variability of neuroimaging features in children with agenesis of the corpus callosum

Background

Agenesis of the corpus callosum (ACC) is a developmental brain malformation associated with a wide spectrum of structural brain abnormalities and genetic loci. To characterize the diverse callosal morphologies and malformations of brain development associated with ACC, we report on the neuroimaging findings of 201 individuals diagnosed with corpus callosal abnormalities.

Methods

We searched through medical records of individuals seen at New York Presbyterian Hospital between 2002 and 2013 and thought to have ACC. We confirmed 201 individuals meeting criteria and used magnetic resonance imaging to characterize morphological variants of the corpus callosum and associated brain malformations.

Results

The majority of individuals displayed hypoplasia or dysplasia of the corpus callosum (N = 160, 80 %). Forty-one (20 %) displayed complete agenesis of the corpus callosum with other abnormalities, while only 18 (9 %) displayed complete agenesis without associated brain abnormalities. White matter abnormalities were more frequent in hypoplasia or dysplasia group than complete agenesis (28.2 % vs 9.8 %, p < 0.05). In contrast, hippocampal abnormalities, colpocephaly, and Probst bundles were significantly more frequent in complete agenesis compared to hypoplasia or dysplasia group.

Conclusions

Collectively, our results underscore the broad diversity of morphological variants of the corpus callosum and associated brain abnormalities in individuals with ACC.

Association of brain metabolism with sulcation and corpus callosum development assessed by MRI in late-onset small fetuses

OBJECTIVE

We sought to determine the relationship between fetal brain metabolism and microstructure expressed by brain sulcation, and corpus callosum (CC) development assessed by fetal brain magnetic resonance (MR) imaging and proton MR spectroscopy ((1)H-MRS).

STUDY DESIGN

A total of 119 fetuses, 64 that were small for gestational age (estimated fetal weight <10th centile and normal umbilical artery Doppler) and 55 controls underwent a 3T MR imaging/(1)H-MRS exam at 37 weeks. Anatomical T2-weighted images were obtained in the 3 orthogonal planes and long echo time (TE) (1)H-MRS acquired from the frontal lobe. Head biometrics, cortical fissure depths (insula, Sylvian, parietooccipital, cingulate, and calcarine), and CC area and biometries were blindly performed by manual and semiautomated delineation using Analyze software and corrected creating ratios for biparietal diameter and frontooccipital diameter, respectively, for group comparison. Spectroscopic data were processed using LCModel software and analyzed as metabolic ratios of N-acetylaspartate (NAA) to choline (Cho), Cho to creatine (Cr), and myo-inositol (Ino) to Cho. Differences between cases and controls were assessed. To test for the association between metabolic ratios and microstructural parameters, bivariate correlation analyses were performed.

RESULTS

Spectroscopic findings showed decreased NAA/Cho and increased Cho/Cr ratios in small fetuses. They also presented smaller head biometrics, shorter and smaller CC, and greater insular and cingulate depths. Frontal lobe NAA/Cho significantly correlated with biparietal diameter (r = 0.268; P = .021), head circumference (r = 0.259; P = .026), CC length (r = 0.265; P = .026), CC area (r = 0.317; P = .007), and the area of 6 from the 7 CC subdivisions. It did not correlate with any of the cortical sulcation parameters evaluated. None of the other metabolic ratios presented significant correlations with cortical development or CC parameters.

CONCLUSION

Frontal lobe NAA/Cho levels-which are considered a surrogate marker of neuronal activity-show a strong association with CC development. These results suggest that both metabolic and callosal alterations may be part of the same process of impaired brain development associated with intrauterine growth restriction.

Agenesis of the corpus callosum in a newborn with turner mosaicism

The agenesis of the corpus callosum results from a failure in the development of the largest fiber bundle that connects cerebral hemispheres. Patient's outcome is influenced by etiology and associated central nervous system malformations. We describe a child with Turner syndrome (TS) mosaicism, with particular phenotype features and a complete agenesis of the corpus callosum. To our knowledge, this is the second case report of TS mosaicism associated with complete agenesis of the corpus callosum. Anatomical brain magnetic resonance imaging and diffusion tensor imaging were useful to confirm the complete absence of the corpus callosum, evaluate associated central nervous system malformations, visualize abnormal white matter tracts (Probst bundles) and assess the remaining commissures.

Agenesis of the corpus callosum and autism: a comprehensive comparison

The corpus callosum, with its ∼200 million axons, remains enigmatic in its contribution to cognition and behaviour. Agenesis of the corpus callosum is a congenital condition in which the corpus callosum fails to develop; such individuals exhibit localized deficits in non-literal language comprehension, humour, theory of mind and social reasoning. These findings together with parent reports suggest that behavioural and cognitive impairments in subjects with callosal agenesis may overlap with the profile of autism spectrum disorders, particularly with respect to impairments in social interaction and communication. To provide a comprehensive test of this hypothesis, we directly compared a group of 26 adults with callosal agenesis to a group of 28 adults with a diagnosis of autism spectrum disorder but no neurological abnormality. All participants had full-scale intelligence quotient scores >78 and groups were matched on age, handedness, and gender ratio. Using the Autism Diagnostic Observation Schedule together with current clinical presentation to assess autistic symptomatology, we found that 8/26 (about a third) of agenesis subjects presented with autism. However, more formal diagnosis additionally involving recollective parent-report measures regarding childhood behaviour showed that only 3/22 met complete formal criteria for an autism spectrum disorder (parent reports were unavailable for four subjects). We found no relationship between intelligence quotient and autism symptomatology in callosal agenesis, nor evidence that the presence of any residual corpus callosum differentiated those who exhibited current autism spectrum symptoms from those who did not. Relative to the autism spectrum comparison group, parent ratings of childhood behaviour indicated children with agenesis were less likely to meet diagnostic criteria for autism, even for those who met autism spectrum criteria as adults, and even though there was no group difference in parent report of current behaviours. The findings suggest two broad conclusions. First, they support the hypothesis that congenital disruption of the corpus callosum constitutes a major risk factor for developing autism. Second, they quantify specific features that distinguish autistic behaviour associated with callosal agenesis from autism more generally. Taken together, these two findings also leverage specific questions for future investigation: what are the distal causes (genetic and environmental) determining both callosal agenesis and its autistic features, and what are the proximal mechanisms by which absence of the callosum might generate autistic symptomatology?

Main congenital cerebral anomalies: how prenatal imaging aids counseling

The purpose of this article is to discuss some common cerebral lesions that may be detected during prenatal screening: corpus callosum dysgenesis, absent septum pellucidum, localized parenchymal ischemic-hemorrhagic lesions, megacisterna magna, Blake's pouch cyst, posterior fossa arachnoid cyst and Dandy-Walker malformation. For each cerebral defect, the main imaging findings are reminded, certain differential diagnoses are discussed and prenatal diagnostic accuracy is analyzed with emphasis on uncertainties encountered during analysis of ultrasound or magnetic resonance images. Detecting cerebral lesions in fetuses requires rapid counseling by neuropediatricians. Keeping in mind that the prenatal diagnostic accuracy is not 100%, the neuropediatricians have to answer the parents' questions regarding the outcome of the unborn child as well as the risk of recurrence for future pregnancies. This article is based on the authors' large experience in both prenatal imaging and neurocounseling. The frequently asked questions are set up. Answers are provided, underscoring the importance of an appropriate description of the cerebral defect, and therefore the pivotal role of prenatal imaging. However, prenatal neurocounseling remains challenging and the parents must be aware of uncertainties regarding both diagnostic accuracy and prognostic evaluation.

Callosal dysgenesis in fetuses with ventriculomegaly: levels of agreement between imaging modalities and postnatal outcome

OBJECTIVE

To assess neurodevelopmental outcome of fetuses diagnosed with callosal abnormalities after referral for ventriculomegaly.

METHODS

This sub-analysis of a prospective study of 430 fetuses, which were referred for ventriculomegaly and underwent sonography and magnetic resonance imaging (MRI), included those fetuses with a diagnosis of corpus callosal abnormalities after recruitment into the main study. Between three and six radiologists independently reviewed ultrasound and MR images and recorded central nervous system (CNS) abnormalities, with final diagnoses being decided by consensus. Postnatal outcomes of fetuses with callosal abnormalities were compared between those with and those without other abnormalities.

RESULTS

Callosal abnormalities were detected in 13% (58/430) of the fetuses referred with ventriculomegaly. Callosal dysgenesis was isolated in 24% (14/58) of these cases, with the remainder complicated by CNS, karyotypic or other major abnormalities. Five fetuses diagnosed prenatally as having isolated callosal abnormalities had additional CNS findings on postnatal assessment. Preconference kappa for callosal abnormalities was 0.76 for ultrasound and 0.78 for MRI, indicating that these investigations had a similar level of operator dependence. Neurodevelopmental outcome was normal or showed only mild delay that resolved in 67% (8/12) children with isolated callosal abnormalities compared to 7% (2/27) in those with non-isolated callosal abnormalities (P = 0.003).

CONCLUSION

Callosal abnormalities are present in a significant proportion of fetuses with a diagnosis of ventriculomegaly. Isolated callosal abnormalities are associated with normal neurodevelopmental outcome in approximately two-thirds of fetuses.

Long-term outcome of antenatally diagnosed agenesis of corpus callosum and cerebellar malformations

Recent advancements in fetal imaging and antenatal care have enabled identification of numerous anomalies including agenesis of corpus callosum and posterior fossa abnormalities. One of the important determinants of long-term prognosis in these conditions is the presence of central nervous system (CNS) and extra-CNS anomalies. The difficulty in confirming the isolated nature of these conditions antenatally and the lack of clear information regarding long-term prognoses makes it difficult for the clinician to provide accurate information to the parents antenatally. Caring for these families would require input from a multidisciplinary team involving obstetricians, geneticists, neurologists, radiologists and neonatologists.

Neurodevelopment after prenatal diagnosis of isolated agenesis of the corpus callosum: an integrative review

OBJECTIVE

To systematically review published data on the neurodevelopment of children that were diagnosed prenatally with isolated agenesis of the corpus callosum.

STUDY DESIGN

Medline and Scopus searches (1960-July 2011); cross-referencing of retrieved articles.

RESULTS

Sixteen reports (132 cases of apparently isolated agenesis of the corpus callosum) were included in the analysis. The rates of normal outcome, borderline or moderate disability and severe disability were 94/132 (71.2%; 95% confidence interval [CI], 63.0-78.3), 18/132 (13.6%; 95% CI, 8.8-20.5), and 22/132 (15.2%; 95% CI, 10.0-22.2), respectively. Magnetic resonance imaging detected additional cerebral abnormalities in 22.5% (95% CI, 12.3-37.5) of apparently isolated agenesis of the corpus callosum cases. In truly isolated agenesis of the corpus callosum (confirmed by magnetic resonance imaging), the rates of normal neurodevelopment and severe disability were 52/69 (75.4%; 95% CI, 64.0-84.0) and 8/69 (11.6%; 95% CI, 6.0-21.2), respectively.

CONCLUSION

Prenatally diagnosed, isolated agenesis of the corpus callosum is usually associated with a favorable outcome. Larger, prospective series are required, as current data are limited, inconsistent, and prevent subgroup analyses (eg, complete vs partial agenesis of the corpus callosum).

Developmental malformation of the corpus callosum: a review of typical callosal development and examples of developmental disorders with callosal involvement

This review provides an overview of the involvement of the corpus callosum (CC) in a variety of developmental disorders that are currently defined exclusively by genetics, developmental insult, and/or behavior. I begin with a general review of CC development, connectivity, and function, followed by discussion of the research methods typically utilized to study the callosum. The bulk of the review concentrates on specific developmental disorders, beginning with agenesis of the corpus callosum (AgCC)-the only condition diagnosed exclusively by callosal anatomy. This is followed by a review of several genetic disorders that commonly result in social impairments and/or psychopathology similar to AgCC (neurofibromatosis-1, Turner syndrome, 22q11.2 deletion syndrome, Williams yndrome, and fragile X) and two forms of prenatal injury (premature birth, fetal alcohol syndrome) known to impact callosal development. Finally, I examine callosal involvement in several common developmental disorders defined exclusively by behavioral patterns (developmental language delay, dyslexia, attention-deficit hyperactive disorder, autism spectrum disorders, and Tourette syndrome).

Neurodevelopmental outcome following prenatal diagnosis of an isolated anomaly of the corpus callosum

OBJECTIVES

To assess the ability of prenatal ultrasound and magnetic resonance imaging (MRI) to diagnose isolated anomalies of the corpus callosum (ACC) and to further document the long-term prognosis following diagnosis.

METHODS

This was a prospective case-control study carried out between 1999 and 2004. Diagnosis was made by a combination of ultrasound and MRI. All infants were examined by a neuropediatrician and parents consented to answer questionnaires (CDI, Ireton's Child Developmental Inventory) in 22 cases, which were matched with 44 control infants. The CDI was used to assess neurodevelopmental outcome in cases and controls. Mean DQ-CDI (development quotient calculated from CDI) values and frequencies of abnormal results were compared between groups, and a meta-analysis of previous studies was performed.

RESULTS

The diagnosis of ACC was made prenatally and confirmed postnatally in 175 cases. The diagnosis was thought to be isolated ACC in 88/175 (50%) cases. Sixty of these 88 cases (68%) underwent termination of pregnancy and one died in utero. Twenty-seven were liveborn, of which 26 were followed up for a median of 50 (range, 30-74) months. Additional anomalies were diagnosed postnatally in four (15%) of these 26 neonates. The control group was significantly better (P < 0.05) compared with the cases diagnosed prenatally with isolated ACC with respect to gross motor, fine motor, language comprehension, numbers and general development, and it was marginally better for letters (P = 0.066). Seven of 26 (27%) (95% CI, 13-46%) infants with ACC over the age of 30 months had neurodevelopmental delay, compared with only one case with borderline developmental delay among the 44 controls (P = 0.006).

CONCLUSION

Prenatal diagnosis of ACC by a combination of ultrasound and MRI is reliable. However, the isolated nature of the anomaly could only be assessed in 85% of our cases. Since counseling is provided at the time of prenatal diagnosis, our population of isolated ACC included the cases that were missed prenatally as being ACC with associated anomalies. A meta-analysis of nine studies suggests that the development of children diagnosed prenatally with isolated ACC is normal in up to 70% (CI 95%, 56-83%) of cases. This means that the prospective risk of neurodevelopmental delay for a fetus with ACC described as isolated prenatally is 27%, compared with 15% for an infant whose diagnosis of isolated ACC is confirmed postnatally.

Distinguishing 3 classes of corpus callosal abnormalities in consanguineous families

OBJECTIVE

We sought to create a classification system for pediatric corpus callosal abnormalities (CCA) based upon midline sagittal brain MRI. We used the term CCA for patients with structural variants of the corpus callosum, excluding patients with interhemispheric cyst variant or pure dysplasia without hypoplasia. Currently, no system exists for nonsyndromic forms of CCA, and attempts to create such a system have been hampered by highly variable morphology in patients with sporadic CCA. We reasoned that any useful strategy should classify affected family members within the same type, and that phenotypic variability should be minimized in patients with recessive disease.

METHODS

We focused recruitment toward multiplex consanguineous families, ascertained 30 patients from 19 consanguineous families, and analyzed clinical features together with brain imaging.

RESULTS

We identified 3 major CCA classes, including hypoplasia, hypoplasia with dysplasia, and complete agenesis. Affected individuals within a given multiplex family usually displayed the same variant of the class of abnormality and they always displayed the same class of abnormality within each family, or they displayed complete agenesis. The system was validated among a second cohort of 10 sporadic patients with CCA.

CONCLUSIONS

The data suggest that complete agenesis may be a common end-phenotype, and implicate multiple overlapping pathways in the etiology of CCA.

Magnetic resonance imaging of the fetus

Fetal magnetic resonance imaging (MRI) has become established as part of clinical practice in many centres worldwide especially when visualization of the central nervous system pathology is required. In this review we summarize the recent literature and provide an overview of fetal development and the commonly encountered fetal pathologies visualized with MRI and illustrated with numerous MR images. We aim to convey the role of fetal MRI in clinical practice and its value as an additional investigation alongside ultrasound yet emphasize the need for caution when interpreting fetal MR images especially where experience is limited.

Assessment of corpus callosum biometric measurements at 18 to 32 weeks' gestation by 3-dimensional sonography

OBJECTIVES

The purposes of this study were to construct reference limits for corpus callosum dimensions measured on images reconstructed from 3-dimensional (3D) sonography and to evaluate the reproducibility of these measurements.

METHODS

Three-dimensional sonographic volumes were acquired transabdominally from an axial view of the head in 361 fetuses cross-sectionally studied at 18 to 32 weeks' gestation. Offline analysis of the fetal brain midsagittal plane was used to evaluate the length and area of the corpus callosum and corpus callosum-cavum septi pellucidi complex. The agreement between 2-dimensional (2D) and 3D measurements as well as the interobserver variability in 3D measurements were assessed by interclass correlation coefficients (ICCs).

RESULTS

Adequate visualization of the midsagittal plane was obtained in 98.1% of the fetuses. A clear distinction between the corpus callosum and cavum septi pellucidi was obtained in 35.7% of the fetuses, whereas in the remaining cases, the corpus callosum-cavum septi pellucidi complex was visualized as a single echogenic structure. The corpus callosum-cavum septi pellucidi complex length (r = 0.806; P < .0001), corpus callosum-cavum septi pellucidi complex area (r = 0.920; P < .0001), and corpus callosum area (r = 0.713; P < .0001) showed a significant linear growth with gestation. A good agreement was found between measurements from both 2D and 3D sonographic views (corpus callosum length ICC, 0.916) as well as between measurements obtained by different observers (corpus callosum-cavum septi pellucidi complex length ICC, 0.936; corpus callosum-cavum septi pellucidi complex area ICC, 0.931).

CONCLUSIONS

Measurements of the corpus callosum and cavum septi pellucidi can be obtained from the midsagittal plane of the fetal brain reconstructed from 3D volumes acquired transabdominally. The constructed nomograms may facilitate the diagnosis of corpus callosum abnormalities.

Corpus callosum agenesis and rehabilitative treatment

Corpus callosum agenesis is a relatively common brain malformation. It can be isolated or included in a complex alteration of brain (or sometimes even whole body) morphology. It has been associated with a number of neuropsychiatric disorders, from subtle neuropsychological deficits to Pervasive Developmental Disorders.

Etiology and pathogenetic mechanisms have been better understood in recent years, due to the availability of more adequate animal models and the relevant progresses in developmental neurosciences. These recent findings are reviewed (through a MedLine search including papers published in the last 5 years and most relevant previously published papers) in view of the potential impact on children's global functioning and on the possible rehabilitative treatment, with an emphasis on the possibility to exploit brain plasticity and on the use of the ICF-CY framework.

Prenatal diagnosis and outcome of partial agenesis and hypoplasia of the corpus callosum

OBJECTIVE

To present antenatal sonographic findings and outcome of fetuses with hypoplasia or partial agenesis of the corpus callosum.

METHODS

The database of our ultrasound laboratory was searched retrospectively for cases of hypoplasia or partial agenesis of the corpus callosum suspected at antenatal neurosonography between 1998 and 2008 and confirmed by pathology or postnatal neuroimaging. In surviving infants, clinical follow-up had been arranged to assess neurodevelopmental outcome.

RESULTS

Nineteen fetuses with callosal underdevelopment were identified at a median gestational age of 22 (range, 21-33) weeks and confirmed at follow-up, including 14 with partial agenesis and five with hypoplasia. Among the 14 fetuses with partial agenesis, there were additional brain findings in 10, including two with absent cavum septi pellucidi, four with mild isolated ventriculomegaly and four with cerebellar abnormalities, two of which also had ventriculomegaly. Pregnancy was terminated electively in seven of the cases with partial agenesis and there was one neonatal death. Among the six surviving infants, neurodevelopmental outcome was appropriate for age in three at follow up, including two cases with isolated partial agenesis of the corpus callosum. Among the five fetuses with prenatally diagnosed callosal hypoplasia, additional anomalies were present in four. Two cases were terminated electively and three were alive at the time of writing, with a median age of 3 years. Among them, apparently normal neurological development was observed in only one case.

CONCLUSIONS

An antenatal diagnosis of callosal underdevelopment is possible by expert sonography. There is often association with other major anomalies. However, even in fetuses with apparently isolated findings, the prognosis is uncertain.

Sonographic diagnosis of fetal cerebral ventriculomegaly: An update

Dilatation of the fetal cerebral ventricles (ventriculomegaly) is a generic sonographic sign that is common to several pathological entities carrying different prognoses. The main causes of fetal ventriculomegaly are aqueductal stenosis, Chiari II malformation, Dandy-Walker complex, and agenesis of the corpus callosum. Ventriculomegaly is easily recognized by ultrasound by measuring the atrial width. This simple measure allows the recognition of mild forms of ventricular dilatation and is used in screening for ventriculomegaly. However, although the diagnosis of ventriculomegaly is easy, the prenatal identification of the cause of ventricular dilatation is a more difficult task. For this purpose the evaluation of the posterior fossa in association with the visualization of the corpus callosum is useful. Research into the causes of ventriculomegaly is clinically useful, since the prognosis mainly depends on the etiology and on the presence of associated abnormalities. In this article the role of prenatal sonography in determining the cause of the ventriculomegaly is reviewed, as well as the prognostic value of the prenatal sonographic findings.

Agenesis of the corpus callosum: an MR imaging analysis of associated abnormalities in the fetus

BACKGROUND AND PURPOSE

Anomalies associated with callosal agenesis (ACC) found postnatally have been well documented. However, to our knowledge, no detailed MR imaging analysis of associated anomalies has been reported in a large cohort of fetuses with ACC. This study will assess those anomalies and compare them with postnatal cohorts of ACC, to identify associated fetal brain abnormalities that may give insight into etiology and outcome.

MATERIALS AND METHODS

All cases of ACC diagnosed on fetal MR imaging during an 11-year period were retrospectively reviewed, including fetal MR imaging, postnatal MR imaging, and autopsy findings. Neurodevelopmental outcome was classified as poor in children with seizures and/or severe neurodevelopmental impairment or in cases of neonatal death.

RESULTS

Twenty-nine cases of ACC were identified. Median gestational age was 26.14 weeks (range, 19.71-36.43 weeks). Twenty-three fetuses had delayed sulcation and/or too-numerous cortical infoldings (abnormal morphology). Fifteen fetuses had cerebellar and/or brain stem abnormalities. Fetal MR imaging findings suggested a genetic syndrome in 5 fetuses and an acquired etiology or genetic/metabolic disorder in 2 fetuses. Findings were confirmed in 8 cases with postnatal MR imaging, except for delayed sulcation and small vermis, and in 4 cases with autopsy, except for periventricular nodular heterotopia and abnormalities in areas not examined by autopsy. Neurodevelopmental outcome was good in 7 and poor in 9 children. Abnormal sulcal morphology and/or infratentorial abnormalities were present in those with poor outcome and absent in those with good outcome.

CONCLUSIONS

ACC is infrequently isolated in fetuses. Abnormal sulcation is common and suggests more diffuse white matter dysgenesis in these fetuses.

Neurodevelopmental outcome in prenatally diagnosed isolated agenesis of the corpus callosum

AIM

To evaluate long-term neurodevelopmental outcomes in children with prenatally diagnosed, isolated agenesis of the corpus callosum (ACC).

METHODS

We retrospectively reviewed data for 20 children born between January 1991 and November 2003 in the Haute-Normandie region of France with a prenatal diagnosis of isolated ACC. We collected data on pre-and postnatal neuroimaging findings, clinical features at birth and neurodevelopmental outcomes.

RESULTS

Follow-up ranged from 3 to 16 years. ACC was complete in 11 patients (55%), partial in 2 (10%), hypoplastic in 3 (15%) and associated with an interhemispheric cyst in 4 (20%). Neurodevelopmental outcome was normal in 11 (55%) patients, including 8 with complete ACC; moderate disability was present in 5 (25%) patients and severe disability in 4 (20%) patients. In 3 of the 4 patients with severe disability, postnatal cerebral magnetic resonance imaging (MRI) showed additional major cerebral abnormalities.

CONCLUSION

Neurodevelopmental outcome was good in most of our patients with isolated ACC, with 80% of patients having normal outcomes or moderate disabilities. A prenatal diagnosis of isolated ACC may not warrant termination of pregnancy. A carefully interpreted prenatal cerebral MRI is crucial to detect associated cerebral abnormalities; a longer follow-up is necessary to look for moderate disabilities.

"How much brain is really necessary?" A case of complex cerebral malformation and its clinical course

The clinical manifestations of cerebral malformations are complex and vary from mild retardation to massive disabilities. A review of the literature suggests that the developmental outcome in these patients depends on the extension, location, and combination of such anomalies. However, the authors present the encouraging clinical course of a girl with a complex cerebral malformation. Despite the severe imaging findings, at the present age of 34 months, the patient developed only a mild psychomotor retardation. This case illustrates that the morphological classification of cerebral malformations does not allow one to predict with certainty whether a child will develop impaired motor and/or higher cognitive functions.