Effects of gender on fetal cortical development: a secondary analysis of a prospective cross-sectional study.

OBJECTIVES: The primary objective was to evaluate the effects of fetal sex on fetal cortical development in low-risk pregnancies. Secondary objective was the evaluate the impact of gestational age. METHODS: This was a secondary analysis of a prospective cross-sectional study on low-risk fetuses undergoing fetal neurosonography between 19 and 34 weeks of gestation. The depth of Sylvian Fissure (SF), Parieto Occipital Fissure (POF) and Calcarine Fissure (CF) were evaluated and related to fetal sex. Neurosonographic variables were normalized for fetal head circumference and expressed as multiple of the median (MoM). RESULTS: A total of 344 fetuses were considered (173 male, 171 female). The baseline characteristic of the two groups were similar except a higher birthweight present in male fetuses (p=0.044). The depth SF (p=0.023) CF (p=0.014) and POF (p=0.046) showed significantly higher values in male fetuses when all the gestational age range was considered. However, when data were controlled for gestational age, these differences resulted significant only after 28 weeks. CONCLUSIONS: Differences in cortical development related to gender occur after 28 weeks of gestation with an increase depth of SF, POF and CF in male fetuses.

Quantification of sulcal emergence timing and its variability in early fetal life: Hemispheric asymmetry and sex difference.

Human fetal brains show regionally different temporal patterns of sulcal emergence following a regular timeline, which may be associated with spatiotemporal patterns of gene expression among cortical regions. This study aims to quantify the timing of sulcal emergence and its temporal variability across typically developing fetuses by fitting a logistic curve to presence or absence of sulcus. We found that the sulcal emergence started from the central to the temporo-parieto-occipital lobes and frontal lobe, and the temporal variability of emergence in most of the sulci was similar between 1 and 2 weeks. Small variability (< 1 week) was found in the left central and postcentral sulci and larger variability (>2 weeks) was shown in the bilateral occipitotemporal and left superior temporal sulci. The temporal variability showed a positive correlation with the emergence timing that may be associated with differential contributions between genetic and environmental factors. Our statistical analysis revealed that the right superior temporal sulcus emerged earlier than the left. Female fetuses showed a trend of earlier sulcal emergence in the right superior temporal sulcus, lower temporal variability in the right intraparietal sulcus, and higher variability in the right precentral sulcus compared to male fetuses. Our quantitative and statistical approach quantified the temporal patterns of sulcal emergence in detail that can be a reference for assessing the normality of developing fetal gyrification.

Cortical Subarachnoid Hemorrhage in Behcet's Disease.

OBJECTIVE: Cortical subarachnoid hemorrhage (cSAH) can be resulted from by a wide variety of causes. A cSAH probably associated with Behcet's disease is herein reported for the first time. CASE REPORT: A 58-year-old male with stable Behcet's disease evaluated for sudden onset headache. Emergency computed tomography disclosed cSAH in the left frontal sulci. A ruptured middle cerebral artery cortical branch aneurysm was found. Surprisingly, this aneurysm obliterated completely after diagnostic catheter angiography. CONCLUSION: This case highlights three important points; First, non-mycotic (non-infectious) distal cerebral artery aneurysms may rarely cause cSAH. Second, distal dissecting aneurysms may rarely become obliterated after diagnostic cerebral angiography. Third, such aneurysms may be one of the long-term consequences of vascular inflammation in Behçet's disease.

Automatic recognition of specific local cortical folding patterns.

The study of local cortical folding patterns showed links with psychiatric illnesses as well as cognitive functions. Despite the tools now available to visualize cortical folds in 3D, manually classifying local sulcal patterns is a time-consuming and tedious task. In fact, 3D visualization of folds helps experts to identify different sulcal patterns but fold variability is so high that the distinction between these patterns sometimes requires the definition of complex criteria, making manual classification difficult and not reliable. However, the assessment of the impact of these patterns on the functional organization of the cortex could benefit from the study of large databases, especially when studying rare patterns. In this paper, several algorithms for the automatic classification of fold patterns are proposed to allow morphological studies to be extended and confirmed on such large databases. Three methods are proposed, the first based on a Support Vector Machine (SVM) classifier, the second on the Scoring by Non-local Image Patch Estimator (SNIPE) approach and the third based on a 3D Convolution Neural Network (CNN). These methods are generic enough to be applicable to a wide range of folding patterns. They are tested on two types of patterns for which there is currently no method to automatically identify them: the Anterior Cingulate Cortex (ACC) patterns and the Power Button Sign (PBS). The two ACC patterns are almost equally present whereas PBS is a particularly rare pattern in the general population. The three models proposed achieve balanced accuracies of approximately 80% for ACC patterns classification and 60% for PBS classification. The CNN-based model is more interesting for the classification of ACC patterns thanks to its rapid execution. However, SVM and SNIPE-based models are more effective in managing unbalanced problems such as PBS recognition.

Temporal Patterns of Emergence and Spatial Distribution of Sulcal Pits During Fetal Life.

Sulcal pits are thought to represent the first cortical folds of primary sulci during neurodevelopment. The uniform spatial distribution of sulcal pits across individuals is hypothesized to be predetermined by a human-specific protomap which is related to functional localization under genetic controls in early fetal life. Thus, it is important to characterize temporal and spatial patterns of sulcal pits in the fetal brain that would provide additional information of functional development of the human brain and crucial insights into abnormal cortical maturation. In this paper, we investigated temporal patterns of emergence and spatial distribution of sulcal pits using 48 typically developing fetal brains in the second half of gestation. We found that the position and spatial variance of sulcal pits in the fetal brain are similar to those in the adult brain, and they are also temporally uniform against dynamic brain growth during fetal life. Furthermore, timing of pit emergence shows a regionally diverse pattern that may be associated with the subdivisions of the protomap. Our findings suggest that sulcal pits in the fetal brain are useful anatomical landmarks containing detailed information of functional localization in early cortical development and maintaining their spatial distribution throughout the human lifetime.

Identification of in vivo Sulci on the External Surface of Eight Adult Chimpanzee Brains: Implications for Interpreting Early Hominin Endocasts.

The only direct source of information about hominin brain evolution comes from the fossil record of endocranial casts (endocasts) that reproduce details of the external morphology of the brain imprinted on the walls of the braincase during life. Surface traces of sulci that separate the brain's convolutions (gyri) are reproduced sporadically on early hominin endocasts. Paleoneurologists rely heavily on published descriptions of sulci on brains of great apes, especially chimpanzees (humans' phylogenetically closest living relatives), to guide their identifications of sulci on ape-sized hominin endocasts. However, the few comprehensive descriptions of cortical sulci published for chimpanzees usually relied on post mortem brains, (now) antiquated terminology for some sulci, and photographs or line drawings from limited perspectives (typically right or left lateral views). The shortage of adequate descriptions of chimpanzee sulcal patterns partly explains why the identities of certain sulci on australopithecine endocasts (e.g., the inferior frontal and middle frontal sulci) have been controversial. Here, we provide images of lateral and dorsal surfaces of 16 hemispheres from 4 male and 4 female adult chimpanzee brains that were obtained using in vivo magnetic resonance imaging. Sulci on the exposed surfaces of the frontal, parietal, temporal, and occipital lobes are identified on the images based on their locations, positions relative to each other, and homologies known from comparative studies of cytoarchitecture in primates. These images and sulcal identifications exceed the quantity and quality of previously published illustrations of chimpanzee brains with comprehensively labeled sulci and, thus, provide a larger number of examples for identifying sulci on hominin endocasts than hitherto available. Our findings, even in a small sample like the present one, overturn published claims that australopithecine endocasts reproduce derived configurations of certain sulci in their frontal lobes that never appear on chimpanzee brains. The sulcal patterns in these new images also suggest that changes in two gyri that bridge between the parietal and occipital lobes may have contributed to cortical reorganization in early hominins. It is our hope that these labeled in vivo chimpanzee brains will assist future researchers in identifying sulci on hominin endocasts, which is a necessary first step in the quest to learn how and when the external morphology of the human cerebral cortex evolved from apelike precursors.

Are Developmental Trajectories of Cortical Folding Comparable Between Cross-sectional Datasets of Fetuses and Preterm Newborns?

Magnetic resonance imaging has proved to be suitable and efficient for in vivo investigation of the early process of brain gyrification in fetuses and preterm newborns but the question remains as to whether cortical-related measurements derived from both cases are comparable or not. Indeed, the developmental folding trajectories drawn up from both populations have not been compared so far, neither from cross-sectional nor from longitudinal datasets. The present study aimed to compare features of cortical folding between healthy fetuses and early imaged preterm newborns on a cross-sectional basis, over a developmental period critical for the folding process (21-36 weeks of gestational age [GA]). A particular attention was carried out to reduce the methodological biases between the 2 populations. To provide an accurate group comparison, several global parameters characterizing the cortical morphometry were derived. In both groups, those metrics provided good proxies for the dramatic brain growth and cortical folding over this developmental period. Except for the cortical volume and the rate of sulci appearance, they depicted different trajectories in both groups suggesting that the transition from into ex utero has a visible impact on cortical morphology that is at least dependent on the GA at birth in preterm newborns.

Convexity Subarachnoid Hemorrhage Due to Cardioembolic Stroke in a Woman with Thyrotoxicosis: Α Case Report.

BACKGROUND: Non-traumatic convexity subarachnoid hemorrhage (cSAH) is a rarely reported condition with a wide spectrum of etiologies. Cerebral ischemia secondary to extracranial or intracranial atherosclerotic disease has been identified as a relatively uncommon cause of cSAH. CASE REPORT: We report a case of cSAH caused by cardioembolic stroke. A 69-year old female patient developed suddenly left-sided face and body weakness and numbness and visual neglect on the left. She was newly detected with paroxysmal atrial fibrillation on the ground of thyrotoxicosis. Brain magnetic resonance imaging revealed ischemia of embolic pattern with cSAH. Further evaluation excluded other cause of hemorrhage. Dilation of leptomeningeal collateral vessels and rupture of pial vessels in distal cortical arteries may caused cSAH. Full anticoagulation was initiated. After one month, her condition improved significantly (NIHSS from 6 to 2). CONCLUSIONS: cSAH may be a rare complication of cardioembolic stroke.

Limited relationships between two-year changes in sulcal morphology and other common neuroimaging indices in the elderly.

Measuring the geometry or morphology of sulcal folds has recently become an important approach to investigating neuroanatomy. However, relationships between cortical sulci and other brain structures are poorly understood. The present study investigates how age-related changes in sulcal width are associated with age-related changes in traditional indices of brain structure such as cortical thickness, and cortical gray matter (GM), white matter (WM), subcortical, and white matter hyperintensity (WMH) volumes. These indices and sulcal width were measured at baseline and at two-year follow up in 185 community-dwelling individuals (91 men) aged 70-89 years. There were significant increases in sulcal width and WMH volume, and significant decreases in all other indices between baseline and follow-up. Sulcal widening was associated with decreases in cortical GM, subcortical and WM volumes. A further association between sulcal width and cortical thickness became non-significant when cortical GM volume was controlled for. Our findings give insights into the mechanisms responsible for cortical sulcal morphology. The relationships between sulcal morphology and other common measures suggest that it could be a more comprehensive measure for clinical classifications than traditional neuroimaging metrics, such as cortical thickness.

Mapping corpus callosum surface reduction in fetal alcohol spectrum disorders with sulci and connectivity-based parcellation.

Introduction: Fetal alcohol spectrum disorders (FASD) range from fetal alcohol syndrome (FAS) to non-syndromic non-specific forms (NS-FASD) that are still underdiagnosed and could benefit from new neuroanatomical markers. The main neuroanatomical manifestation of prenatal alcohol exposure on developmental toxicity is the reduction in brain size, but repeated imaging observations have long driven the attention on the corpus callosum (CC), without being all convergent. Our study proposed a new segmentation of the CC that relies on both a sulci-based cortical segmentation and the "hemispherotopic" organization of the transcallosal fibers. Methods: We collected a monocentric series of 37 subjects with FAS, 28 with NS-FASD, and 38 with typical development (6 to 25 years old) using brain MRI (1.5T). Associating T1- and diffusion-weighted imaging, we projected a sulci-based cortical segmentation of the hemispheres on the midsagittal section of the CC, resulting in seven homologous anterior-posterior parcels (frontopolar, anterior and posterior prefrontal, precentral, postcentral, parietal, and occipital). We measured the effect of FASD on the area of callosal and cortical parcels by considering age, sex, and brain size as linear covariates. The surface proportion of the corresponding cortical parcel was introduced as an additional covariate. We performed a normative analysis to identify subjects with an abnormally small parcel. Results: All callosal and cortical parcels were smaller in the FASD group compared with controls. When accounting for age, sex, and brain size, only the postcentral (η2 = 6.5%, pFDR = 0.032) callosal parcel and % of the cortical parcel (η2 = 8.9%, pFDR = 0.007) were still smaller. Adding the surface proportion (%) of the corresponding cortical parcel to the model, only the occipital parcel was persistently reduced in the FASD group (η2 = 5.7%, pFDR = 0.014). In the normative analysis, we found an excess of subjects with FASD with abnormally small precentral and postcentral (peri-isthmic) and posterior-splenial parcels (pFDR < 0.05). Conclusion: The objective sulcal and connectivity-based method of CC parcellation proved to be useful not only in confirming posterior-splenial damage in FASD but also in the narrowing of the peri-isthmic region strongly associated with a specific size reduction in the corresponding postcentral cortical region (postcentral gyrus). The normative analysis showed that this type of callosal segmentation could provide a clinically relevant neuroanatomical endophenotype, even in NS-FASD.

Automatic labeling of cortical sulci using patch- or CNN-based segmentation techniques combined with bottom-up geometric constraints.

The extreme variability of the folding pattern of the human cortex makes the recognition of cortical sulci, both automatic and manual, particularly challenging. Reliable identification of the human cortical sulci in its entirety, is extremely difficult and is practiced by only a few experts. Moreover, these sulci correspond to more than a hundred different structures, which makes manual labeling long and fastidious and therefore limits access to large labeled databases to train machine learning. Here, we seek to improve the current model proposed in the Morphologist toolbox, a widely used sulcus recognition toolbox included in the BrainVISA package. Two novel approaches are proposed: patch-based multi-atlas segmentation (MAS) techniques and convolutional neural network (CNN)-based approaches. Both are currently applied for anatomical segmentations because they embed much better representations of inter-subject variability than approaches based on a single template atlas. However, these methods typically focus on voxel-wise labeling, disregarding certain geometrical and topological properties of interest for sulcus morphometry. Therefore, we propose to refine these approaches with domain specific bottom-up geometric constraints provided by the Morphologist toolbox. These constraints are utilized to provide a single sulcus label to each topologically elementary fold, the building blocks of the pattern recognition problem. To eliminate the shortcomings associated with the Morphologist's pre-segmentation into elementary folds, we complement this regularization scheme using a top-down perspective which triggers an additional cleavage of the elementary folds when required. All the newly proposed models outperform the current Morphologist model, the most efficient being a CNN U-Net-based approach which carries out sulcus recognition within a few seconds.

Decompressive Craniectomy: A Preliminary Study of Comparative Radiographic Characteristics Predicting Outcome in Malignant Ischemic Stroke.

OBJECTIVE: Decompressive craniectomy (DC) has been advocated as a lifesaving procedure in management of patients with raised intracranial pressure due to malignant ischemic stroke (MIS). The aim of this study was to identify comparative radiologic parameters after DC to predict functional outcome at 6 months in patients with MIS. METHODS: A retrospective analysis (2015-2018) of patients (median age 54 years; range, 29-80 years) with MIS who underwent postoperative computed tomography within 24 hours of DC was performed. Multivariate regression analysis was computed to predict clinical outcome at 6 months based on the Glasgow Coma Outcome Scale Extended. RESULTS: With median National Institutes of Health Stroke Scale score of 20 (range, 3-33), mean preoperative stroke volume was 250 ± 75 cm3. Median Glasgow Coma Outcome Scale Extended score at 6 months was 4. Multivariate regression analysis showed that the comparative radiographic characteristics of absence of effacement of cortical sulci (odds ratio 2.88; 95% confidence interval, 1.22-20.71; P = 0.02), absence of hemorrhagic transformation (odds ratio 1.09; 95% confidence interval, 1.99-12.89; P = 0.03), and absence of compression of lateral ventricles (odds ratio 3.75; 95% confidence interval, 1.28-22.4; P = 0.05) on postoperative computed tomography scan were significant independent predictors of good functional outcome (Glasgow Coma Outcome Scale Extended score 5-8). CONCLUSIONS: The comparative radiographic characteristics of absence of effacement of cortical sulci, hemorrhagic transformation, and compression of the lateral ventricles after DC in patients with MIS bore a significant relationship to predicting clinical outcome at 6 months.

Incomplete Hippocampal Inversion: A Comprehensive MRI Study of Over 2000 Subjects.

The incomplete-hippocampal-inversion (IHI), also known as malrotation, is an atypical anatomical pattern of the hippocampus, which has been reported in healthy subjects in different studies. However, extensive characterization of IHI in a large sample has not yet been performed. Furthermore, it is unclear whether IHI are restricted to the medial-temporal lobe or are associated with more extensive anatomical changes. Here, we studied the characteristics of IHI in a community-based sample of 2008 subjects of the IMAGEN database and their association with extra-hippocampal anatomical variations. The presence of IHI was assessed on T1-weighted anatomical magnetic resonance imaging (MRI) using visual criteria. We assessed the association of IHI with other anatomical changes throughout the brain using automatic morphometry of cortical sulci. We found that IHI were much more frequent in the left hippocampus (left: 17%, right: 6%, χ(2)-test, p < 10(-28)). Compared to subjects without IHI, subjects with IHI displayed morphological changes in several sulci located mainly in the limbic lobe. Our results demonstrate that IHI are a common left-sided phenomenon in normal subjects and that they are associated with morphological changes outside the medial temporal lobe.