Cerebral sparganosis in a child with corpus callosum invasion: a case report

BACKGROUND

Invasion of the corpus callosum by sparganosis is rare in children. After invading the corpus callosum, sparganosis has various migration modes, which can break through the ependyma and enter the ventricles, thus causing secondary migratory brain injury.

CASE PRESENTATION

A girl aged 4 years and 7 months presented with left lower limb paralysis for more than 50 days. Blood examination showed that the proportion and absolute number of eosinophils in the peripheral blood were increased. Furthermore, enzyme-linked immunosorbent assay of serum and cerebrospinal fluid samples revealed positivity for IgG and IgM antibodies for sparganosis. Initial magnetic resonance imaging (MRI) revealed ring-like enhancements in the right frontoparietal cortex, subcortical white matter, and splenium of the corpus callosum. Within 2 months, a fourth follow-up MRI showed that the lesion had spread to the left parietal cortex, subcortical white matter, and deep white matter in the right occipital lobe and right ventricular choroid plexus, with left parietal leptomeningeal enhancement.

CONCLUSION

Migratory movement is one of the characteristics of cerebral sparganosis. When sparganosis invades the corpus callosum, clinicians should be aware that it may then break through the ependyma and enter the lateral ventricles, leading to secondary migratory brain injury. Short-term follow-up MRI is necessary to evaluate the migration mode of sparganosis and dynamically guide treatment strategies.

The genetic architecture of the corpus callosum and its genetic overlap with common neuropsychiatric diseases

BACKGROUND

The corpus callosum (CC) is the main structure transferring information between the cerebral hemispheres. Although previous large-scale genome-wide association study (GWAS) has illustrated the genetic architecture of white matter integrity of CC, CC volume is less stressed.

METHODS

Using MRI data from 33,861 individuals in UK Biobank, we conducted univariate and multivariate GWAS for CC fractional anisotropy (FA) and volume with PLINK 2.0 and MOSTest. All discovered SNPs in the multivariate framework were functionally annotated in FUMA v1.3.8. In the meanwhile, a series of gene property analyses was conducted simultaneously. In addition, we estimated genetic relationship between CC metrics and other neuropsychiatric traits and diseases.

RESULTS

We identified a total of 36 and 82 significant genomic loci for CC FA and volume (P < 5 × 10^-8). And 53 and 27 genes were respectively mapped by four mapping strategies. For CC volume, gene-set analysis revealed pathways mainly relating to cell migration; cell-type analysis found the top enrichment in neuroglia while for CC FA in GABAergic neurons. Furthermore, we found a lot of genetic overlap and shared loci between CC FA and volume and common neuropsychiatric diseases.

DISCUSSION

Collectively, this study helps to better understand the genetic architecture of whole CC and CC subregions. However, the way to divide CC FA and volume in our study restricts the interpretations of our results. Future work will be needed to pay attention to the genetic structure of white matter volume, and an appropriate division of CC may help to better understand CC structure.

An Investigation of Age-related Neuropathophysiology in Autism Spectrum Disorder Using Fixel-based Analysis of Corpus Callosum White Matter Micro- and Macrostructure

Fixel-based analysis was used to probe age-related changes in white matter micro- and macrostructure of the corpus callosum between participants with (N = 54) and without (N = 50) autism spectrum disorder (ASD). Data were obtained from the Autism Brain Imaging Data Exchange-II (ABIDE-II). Compared to age-matched controls, young adolescents with ASD (11.19 ± 7.54 years) showed reduced macroscopic fiber cross-section (logFC) and combined fiber-density and cross-section (FDC). Reduced fiber-density (FD) and FDC was noted in a marginally older (13.87 ± 3.15 years) ASD cohort. Among the oldest ASD cohort (17.07 ± 3.56 years), a non-significant trend indicative of reduced FD was noted. White matter aberration appears greatest and most widespread among younger ASD cohorts. This supports the suggestion that some early neuropathophysiological indicators in ASD may dissipate with age.

How I do it? Surgical removal of a corpus callosum arteriovenous malformation using a robotic digital microscope

BACKGROUND

This report described the surgical nuance of a challenging deep-seated corpus callosum arteriovenous malformation (AVM) using a novel robotic digital microscope.

METHOD

A 64-year-old male was admitted to treat a ruptured corpus callosum AVM. In order to facilitate surgical manipulation under the robotic digital microscope, a gravity-assisted supine position was utilized. Intraoperatively, identifying and preserving the transit and bystander artery is important while skeletonizing the anterior cerebral artery. The nidus was totally resected and the patient was discharged without sequella.

CONCLUSION

It is feasible to perform complicated AVM resection under the robotic digital microscope with a rigorous surgical plan.

Atypical cytotoxic lesion and hemorrhagic involvement of the corpus callosum in severe COVID-19 infection

Introduction/Background The COVID-19 pandemic has resulted in a large number of deaths and has caused a significant increase in population morbidity. This viral infection has been associated with different neurological symptoms and complications that do not have a clear pathophysiological mechanism and exact implications for these patients. Case Presentation A 40-year-old man with COVID-19 and co-infection with Klebsiella pneumoniae KPC presented extensive pulmonary involvement and required comprehensive management in the intensive care unit (ICU). During his hospitalization, he developed neurological symptoms with evidence of involvement of the corpus callosum, which was attributed to the cytotoxic lesion of the corpus callosum (CLOCC). After several months of interdisciplinary management in the ICU, there was a progressive improvement in his general condition, with discharge from the hospital without significant sequelae, with follow-up images showing complete involvement of the corpus callosum due to what was considered an atypical cytotoxic lesion of the corpus callosum. Conclusion Imaging features of CLOCCs are known to be temporary, but in the setting of COVID-19, it has not yet been determined if this is true and further studies are needed. Nonetheless, the one-year follow-up of our patient makes us believe that this atypical involvement of the corpus callosum described in severe SARS-CoV-2 infections is not transitory, even if there are no neurologic sequelae.

Corpus callosum structural characteristics in very preterm children and adolescents: Developmental trajectory and relationship to cognitive functioning

Previous studies suggest that structural alteration of the corpus callosum, i.e., the largest white matter commissural pathway, occurs after a preterm birth in the neonatal period and lasts across development. The present study aims to unravel corpus callosum structural characteristics across childhood and adolescence in very preterm (VPT) individuals, and their associations with general intellectual, executive and socio-emotional functioning. Neuropsychological assessments, T1-weighted and multi-shell diffusion MRI were collected in 79 VPT and 46 full term controls aged 6-14 years. Volumetric, diffusion tensor and neurite orientation dispersion and density imaging (NODDI) measures were extracted on 7 callosal portions using TractSeg. A multivariate data-driven approach (partial least squares correlation) and a cohort-based age normative modelling approach were used to explore associations between callosal characteristics and neuropsychological outcomes. The VPT and a full-term control groups showed similar trends of white-matter maturation over time, i.e., increase FA and reduced ODI, in all callosal segments, that was associated with increase in general intellectual functioning. However, using a cohort-based age-related normative modelling, findings show atypical pattern of callosal development in the VPT group, with reduced callosal maturation over time that was associated with poorer general intellectual and working memory functioning, as well as with lower gestational age.

Microsurgical anatomy of the anterior cerebral artery and the arterial supply of the cingulate gyrus

PURPOSE

The cingulate gyrus is a potential surgical area to treat tumours, psychiatric diseases, intractable pain and vascular malformations. The aim of the study was to define the topographic anatomy and arterial supply of the cingulate gyrus located on the medial surface of the cerebral hemisphere.

METHODS

We studied thirty-six hemispheres, each hemisected in the midsagittal plane. The vertical thickness of the cingulate gyrus was measured at the anterior commissure (AC), posterior commissure (PC), and genu levels of the corpus callosum. The branches of the anterior and posterior cerebral arteries supplying each zone were noted separately. The arterial pathways were transformed to digital data in AutoCAD to identify the condensation and reduction areas.

RESULTS

The mean AC-PC distance was 27.17 ± 1.63 mm. The thinnest region was the genu level of the corpus callosum (10.29 mm). The superior internal parietal artery (SIPA), inferior internal parietal artery (IIPA) and pericallosal artery (PrCA) supplied all zones of the cingulate gyrus. The anterior zone received the greatest supply. The arterial condensation and reduction areas on both sides of cingulate gyrus and its x, y, and z coordinates specified.

CONCLUSIONS

The target cingulotomy (TC) area was determined for anterior cingulotomy. The properties of the TC area are that the thinnest region of the cingulate gyrus is supplied relatively less than other areas and is close to the anterior cingulotomy areas in the literature. The arterial reduction area (ARA) was found to be suitable for corpus callosotomy in terms of avoiding haemorrhage.

Structural integrity of corpus callosum in patients with migraine: a diffusion tensor imaging study

The aim of this study was to compare structural changes of corpus callosum (CC), which is the largest collection of white matter in the brain, among migraineurs and healthy controls (HC). Diffusion tensor imaging (DTI) method which provides information about microscopic organization of the cell, especially white matter was used for this purpose. Fifty-one patients who were diagnosed with migraine and 44 age- and sex-matched HC were included in the study. Socio-demographic and clinical characteristics of the patients were noted. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) measurements of CC genu, splenium, and body were performed for all participants. A significant difference was determined between migraine patients and HC regarding the FA values in the genu of CC (p < 0.001). When the clinical data of migraine patients and FA values in the genu of CC were analyzed via linear regression analysis, no significant finding was detected (p > 0.05). In conclusion, it can be suggested that there are microstructural changes in the CC of migraneurs; however, the clinical variable associated with this structural deterioration could not be determined.

Induction of interhemispheric facilitation by short bursts of transcranial alternating current stimulation

Interhemispheric facilitation (IHF) describes potentiation of motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) over primary motor cortex (M1), when they are preceded (3-6 ms) by conditioning TMS below motor threshold (MT) delivered over the opposite M1. This effect is however obtained only when the conditioning stimulation is sufficiently circumscribed. In paired associative protocols, (500 ms) bursts of 140 Hz transcranial alternating current stimulation (tACS) interact with the state of neural circuits in the opposite hemisphere in a similar manner to sub-threshold TMS. We hypothesised that tACS applied over M1 would elevate the amplitudes of MEPs elicited by suprathreshold TMS applied 6 ms later over the opposite M1. Thirty healthy right-handed participants were tested. In a control condition, MEPs were recorded in right flexor carpi radialis (rFCR) following 120% resting MT TMS over left M1. In 11 experimental conditions, 1 mA (peak-to-peak) 140 Hz (30, 100, 500 ms) or 670 Hz (6, 12, 100, 500 ms) tACS, or 100-640 Hz (6, 12, 100, 500 ms) transcranial random noise stimulation (tRNS), was delivered over right M1, 6 ms in advance of the TMS. IHF was obtained by conditioning with 30 ms (but not 100 or 500 ms) 140 Hz tACS. The magnitude of IHF (12% increase; d = 0.56 (0.21-0.98)) was within the range reported for dual-coil TMS studies. Conditioning by 670 Hz tACS or tRNS had no effect. Our findings indicate that short bursts of 140 Hz tACS, applied over M1, have distributed effects similar to those of subthreshold TMS.

Functional topography of the corpus callosum as revealed by fMRI and behavioural studies of control subjects and patients with callosal resection

The concept of a topographical map of the corpus callosum (CC), the main interhemispheric commissure, has emerged from human lesion studies and from anatomical tracing investigations in other mammals. Over the last few years, a rising number of researchers have been reporting functional magnetic resonance imaging (fMRI) activation in also the CC. This short review summarizes the functional and behavioral studies performed in groups of healthy subjects and in patients undergone to partial or total callosal resection, and it is focused on the work conducted by the authors. Functional data have been collected by diffusion tensor imaging and tractography (DTI and DTT) and functional magnetic resonance imaging (fMRI), both techniques allowing to expand and refine our knowledge of the commissure. Neuropsychological test were also administered, and simple behavioral task, as imitation perspective and mental rotation ability, were analyzed. These researches added new insight on the topographic organization of the human CC. By combining DTT and fMRI it was possible to observe that the callosal crossing points of interhemispheric fibers connecting homologous primary sensory cortices, correspond to the CC sites where the fMRI activation elicited by peripheral stimulation was detected. In addition, CC activation during imitation and mental rotation performance was also reported. These studies demonstrated the presence of specific callosal fiber tracts that cross the commissure in the genu, body, and splenium, at sites showing fMRI activation, consistently with cortical activated areas. Altogether, these findings lend further support to the notion that the CC displays a functional topographic organization, also related to specific behavior.

Corpus callosum organization and its implication to core and co-occurring symptoms of Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is characterized by social interaction and communication deficits, repetitive behavior and often by co-occurring conditions such as language and non-verbal IQ development delays. Previous studies reported that those behavioral abnormalities can be associated with corpus callosum organization. However, little is known about the specific differences in white matter structure of the corpus callosum parts in children with ASD and TD peers and their relationships to core and co-occurring symptoms of ASD. The aim of the study was to investigate the volumetric and microstructural characteristics of the corpus callosum parts crucially involved in social, language, and non-verbal IQ behavior in primary-school-aged children with ASD and to assess the relationships between these characteristics and behavioral measures. 38 children (19 with ASD and 19 typically developing (TD) controls) were scanned using diffusion-weighted MRI and assessed with behavioral tests. The tractography of the corpus callosum parts were performed using Quantitative Imaging Toolkit software; diffusivity and volumetric measurements were extracted for the analysis. In the ASD group, fractional anisotropy (FA) was decreased across the supplementary motor area and the ventromedial prefrontal cortex, and axial diffusivity (AD) was reduced across each of the corpus callosum parts in comparison to the TD group. Importantly, the AD decrease was related to worse language skills and more severe autistic traits in individuals with ASD. The microstructure of the corpus callosum parts differs between children with and without ASD. Abnormalities in white matter organization of the corpus callosum parts are associated with core and co-occurring symptoms of ASD.

Neuronal nitric oxide synthase positive neurons in the human corpus callosum: a possible link with the callosal blood-oxygen-level dependent (BOLD) effect

Brain functions have been investigated in the past decades via the blood-oxygen-level dependent (BOLD) effect using functional magnetic resonance imaging. One hypothesis explaining the BOLD effect involves the Nitric Oxide (NO) gaseous neurotransmitter, possibly released also by cells in the corpus callosum (CC). The eventual presence of NO releasing neurons and/or glial cells in the CC can be assessed by immunohistochemistry. Serial sections both from paraffin-embedded and frozen samples of CC obtained from adult human brains autopsy were studied with immunohistochemistry and immunofluorescence analysis, using an antibody against the neuronal isoform of Nitric Oxide Synthase (nNOS), the enzyme synthetizing the NO. The staining revealed the presence of many nNOS-immunopositive cells in the CC, shown to be neurons with immunofluorescence. Neuronal NOS-positive neurons presented different morphologies, were more numerous 4 mm apart from the midline, and displayed a peak in the body of the CC. In some cases, they were located at the upper boundary of the CC, more densely packed in the proximity of the callosal arterioles. The significant presence of nNOS-immunopositive neurons within the commissure suggests their probable role in the CC neurovascular regulation in the adult brain and could explain the BOLD effect detected in human CC.

Acquired hump of the corpus callosum: a rare morphologic complication after CSF shunting

PURPOSE

To present the longitudinal MR imaging of 4 children with an acquired corpus callosum hump, in order to demonstrate graphically that this represents a dysmorphology caused through a constellation of pre-existing pathology, timing, and complications of treatment.

MATERIALS AND METHODS

Four cases with a corpus callosum hump were evaluated for common findings in the clinical history and on MRI scans. Those patients with available follow-up imaging were specifically evaluated for the presence of the hump on initial neonatal imaging and for evidence of development and progression of the deformity over time. Corpus callosum length was measured and compared against normal standards.

RESULTS AND CONCLUSION

Congenital hydrocephalus, chronic ventricular over-shunting, white matter volume loss, and lateral ventricle communication were common to all cases. Corpus callosum length was above normal values. The corpus callosum hump term was previously described as dysplasia but was not present on initial scans in our cases. We conclude that the corpus callosum hump can be acquired as a complication of over-shunting in children with congenital hydrocephalus. Thus, we present our examples as "acquired hump of the corpus callosum," which differs from the prior example. We postulate that the lengthening of the stretched corpus callosum due to chronic hydrocephalus in the pre-myelinated state renders it unable to return to its normal shape when the ventricles are drained. Over-shunting of both lateral ventricles simultaneously in the absence of a septum pellucidum results in collapse and folding in of the corpus callosum on itself, resulting in the hump.

Mechanical behavior of the hippocampus and corpus callosum: An attempt to reconcile ex vivo with in vivo and micro with macro properties

Mechanical properties of brain tissue are very complex and vary with the species, region, method, and dynamic range, and between in vivo and ex vivo measurements. To reconcile this variability, we investigated in vivo and ex vivo stiffness properties of two distinct regions in the human and mouse brain - the hippocampus (HP) and the corpus callosum (CC) - using different methods. Under quasi-static conditions, we examined ex vivo murine HP and CC by atomic force microscopy (AFM). Between 16 and 40Hz, we investigated the in vivo brains of healthy volunteers by magnetic resonance elastography (MRE) in a 3-T clinical scanner. At high-frequency stimulation between 1000 and 1400Hz, we investigated the murine HP and CC ex vivo and in vivo with MRE in a 7-T preclinical system. HP and CC showed pronounced stiffness dispersion, as reflected by a factor of 32-36 increase in shear modulus from AFM to low-frequency human MRE and a 25-fold higher shear wave velocity in murine MRE than in human MRE. At low frequencies, HP was softer than CC, in both ex vivo mouse specimens (p < 0.05) and in vivo human brains (p < 0.01) while, at high frequencies, CC was softer than HP under in vivo (p < 0.01) and ex vivo (p < 0.05) conditions. The standard linear solid model comprising three elements reproduced the observed HP and CC stiffness dispersions, while other two- and three-element models failed. Our results indicate a remarkable consistency of brain stiffness across species, ex vivo and in vivo states, and different measurement techniques when marked viscoelastic dispersion properties combining equilibrium and non-equilibrium mechanical elements are considered.

Complete agenesis of corpus callosum with a rare neuropsychiatric presentation: A case report

Corpus callosum agenesis is a rare phenomenon that might be associated with neuropsychiatric disorders. We present a 28-year-old woman with complete corpus callosum agenesis who presented with mood disturbance, psychosis, and delusional symptoms with schizophrenia diagnosis. She had a good response to antipsychotic therapy with risperidone.

Spatial and temporal alterations of developing oligodendrocytes induced by repeated sevoflurane exposure in neonatal mice

The general anesthesia associated with long-term cognitive impairment has been causing the concern of the whole society. In particular, repeated anesthetic exposures may affect executive function, processing speed, and fine motor skills, which all directly depended on the functions of oligodendrocytes, myelin, and axons. However, the underlying mechanisms are still largely unknown. To investigate the spatial and temporal alterations in oligodendrocytes in the corpus callosum (CC) and hippocampus following repeated sevoflurane exposures (3%, for 2 h) from postnatal day 6 (P6) to P8, we used immunofluorescence, Western blot, and a battery of behavioral tests. As previously stated, we confirmed that early anesthetic exposures hampered both cognitive and motor performance during puberty in the rotarod and banes tests. Intriguingly, we discovered that the proliferation of oligodendrocyte progenitor cells (OPCs) was immediately enhanced after general anesthesia in the CC and hippocampus from P8 to P32. From P8 through P15, the overall oligodendrocyte population remained constant. However, along with the structural myelin abnormalities, the matured oligodendrocytes statistically reduced in the CC (from P15) and hippocampus (from P32). Administration of clemastine, which could induce OPC differentiation and myelin formation, significantly increased matured oligodendrocytes and promoted myelination and cognition. Collectively, we first demonstrated the bi-directional influence of early sevoflurane exposures on oligodendrocyte maturation and proliferation, which contributes to the cognitive impairment induced by general anesthesia. These findings illustrated the dynamic changes in oligodendrocytes in the developing brain following anesthetic exposures, as well as possible therapeutic strategies for multiple general anesthesia associated cognitive impairment.

White matter microstructure predicts measures of clinical symptoms in chronic back pain patients

Chronic back pain (CBP) has extensive clinical and social implications for its sufferers and is a major source of disability. Chronic pain has previously been shown to have central neural factors underpinning it, including the loss of white matter (WM), however traditional methods of analyzing WM microstructure have produced mixed and unclear results. To better understand these factors, we assessed the WM microstructure of 50 patients and 40 healthy controls (HC) using diffusion-weighted imaging. The data were analyzed using fixel-based analysis (FBA), a higher-order diffusion modelling technique applied to CBP for the first time here. Subjects also answered questionnaires relating to pain, disability, catastrophizing, and mood disorders, to establish the relationship between fixelwise metrics and clinical symptoms. FBA determined that, compared to HC, CBP patients had: 1) lower fibre density (FD) in several tracts, specifically the right anterior and bilateral superior thalamic radiations, right spinothalamic tract, right middle cerebellar peduncle, and the body and splenium of corpus callosum; 2) higher FD in the genu of corpus callosum; and 3) lower FDC - a combined fibre density and cross-section measure - in the bilateral spinothalamic tracts and right anterior thalamic radiation. Exploratory correlations showed strong negative relationships between fixelwise metrics and clinical questionnaire scores, especially pain catastrophizing. These results have important implications for the intake and processing of sensory data in CBP that warrant further investigation.

Mapping myelin in white matter with T1-weighted/T2-weighted maps: discrepancy with histology and other myelin MRI measures

The ratio of T1-weighted/T2-weighted magnetic resonance images (T1w/T2w MRI) has been successfully applied at the cortical level since 2011 and is now one of the most used myelin mapping methods. However, no reports have explored the histological validity of T1w/T2w myelin mapping in white matter. Here we compare T1w/T2w with ex vivo postmortem histology and in vivo MRI methods, namely quantitative susceptibility mapping (QSM) and multi-echo T2 myelin water fraction (MWF) mapping techniques. We report a discrepancy between T1w/T2w myelin maps of the human corpus callosum and the histology and analyse the putative causes behind such discrepancy. T1w/T2w does not positively correlate with Luxol Fast Blue (LFB)-Optical Density but shows a weak to moderate, yet significant, negative correlation. On the contrary, MWF is strongly and positively correlated with LFB, whereas T1w/T2w and MWF maps are weakly negatively correlated. The discrepancy between T1w/T2w MRI maps, MWF and histological myelin maps suggests caution in using T1w/T2w as a white matter mapping method at the callosal level. While T1w/T2w imaging may correlate with myelin content at the cortical level, it is not a specific method to map myelin density in white matter.

Behavioral disinhibition following corpus callosotomy done for colloid cyst excision in 15-year-old girl: A case report and literature review

Background

There is a growing body of literature suggesting that the corpus callosum plays an important role in behavior. While behavioral deficits are a rare complication following callosotomy, they are well-documented in agenesis of the corpus callosum (AgCC), with emerging evidence reporting disinhibition among children with AgCC.

Case Description

A 15-year-old girl had undergone a right frontal craniotomy and excision of a third ventricle colloid cyst using the transcallosal approach. Ten days after the operation, she was readmitted for progressive symptoms of behavioral disinhibition. Postoperative magnetic resonance imaging of the brain showed mild-to-moderate bilateral edematous changes along the operative bed, with no other significant findings.

Conclusion

To the best of the authors' knowledge, this is the first report in literature to describe behavioral disinhibition occurring as a sequelae to a surgical procedure involving callosotomy.

Restricted diffusion of the callosal splenium is highly specific for seizures in neonates

BACKGROUND

To determine whether restricted diffusion of the callosal splenium is specific for seizure activity in neonates.

METHODS

We performed a retrospective chart review of 123 neonates who had a diagnosis of hypoxic ischemic encephalopathy (HIE) who underwent therapeutic cooling and had magnetic resonance imaging (MRI) within the first 10 days of life. The regions examined for injury include the callosal splenium, cortex, deep gray matter, and subcortical white matter. Neurodevelopmental outcomes were secondarily assessed using the Bayley Scales of Infant Development at 12 to 18 months of age and > 18 months of age. APGAR scores and pH, two important markers of hypoxia/ischemia and encephalopathy, were also analyzed in relation to these outcomes.

RESULTS

Approximately 41% of the neonates had at least one abnormal region on brain MRI, and 21% had abnormal signal in the splenium. Clinical and/or electrographic seizures were documented in 32%. Changes in the splenium had a sensitivity of 54%, specificity of 94%, and positive predictive value of 81% for seizure presence. The presence of seizures and splenium lesion was associated poor developmental outcomes at 12 to 18 months of age. APGAR scores at 10 minutes, but not lowest pH was associated with splenial changes.

CONCLUSIONS

Restricted diffusion of the callosal splenium is specific for recent seizures in neonates with HIE. Seizures and splenial lesion represent risk factors for poor neurodevelopmental outcomes. Child neurologists and neonatologists should consider splenial signal abnormality in their assessment of neonates at risk for seizures and counsel families about likely outcomes accordingly.

Associations between corpus callosum damage, clinical disability, and surface-based homologous inter-hemispheric connectivity in multiple sclerosis

Axonal damage in the corpus callosum is prevalent in multiple sclerosis (MS). Although callosal damage is associated with disrupted functional connectivity between hemispheres, it is unclear how this relates to cognitive and physical disability. We investigated this phenomenon using advanced measures of microstructural integrity in the corpus callosum and surface-based homologous inter-hemispheric connectivity (sHIC) in the cortex. We found that sHIC was significantly decreased in primary motor, somatosensory, visual, and temporal cortical areas in a group of 36 participants with MS (29 relapsing-remitting, 4 secondary progressive MS, and 3 primary-progressive MS) compared with 42 healthy controls (cluster level, p < 0.05). In participants with MS, global sHIC correlated with fractional anisotropy and restricted volume fraction in the posterior segment of the corpus callosum (r = 0.426, p = 0.013; r = 0.399, p = 0.020, respectively). Lower sHIC, particularly in somatomotor and posterior cortical areas, was associated with cognitive impairment and higher disability scores on the Expanded Disability Status Scale (EDSS). We demonstrated that higher levels of sHIC attenuated the effects of posterior callosal damage on physical disability and cognitive dysfunction, as measured by the EDSS and Brief Visuospatial Memory Test-Revised (interaction effect, p < 0.05). We also observed a positive association between global sHIC and years of education (r = 0.402, p = 0.018), supporting the phenomenon of "brain reserve" in MS. Our data suggest that preserved sHIC helps prevent cognitive and physical decline in MS.

Evaluation of the corpus callosum using magnetic resonance imaging histogram analysis in autism spectrum disorder

BACKGROUND

Histogram analysis is a texture analysis method that can be used in medical images. Quantitative values of the intensity of images can be obtained with histogram analysis. It aimed to evaluate corpus callosum in magnetic resonance images (MRIs) using histogram analysis of pediatric patients with autism spectrum disorder (ASD) to compare them with healthy controls.

METHODS

This study included 29 children with ASD and 29 healthy children with normal brain MRI. High-resolution three-dimensional turbo field echo images were obtained with a 1.5 T scanner device for brain magnetic resonance imaging. On the corpus callosum in the sagittal T1-weighted images obtained, mean gray level density (mean), the standard deviation, median, minimum, maximum, entropy, variance, skewness, kurtosis, uniformity, size % L, size % M, size % U, and percentile parameters were measured.

RESULTS

In ASD patients, mean, standard deviation, maximum, median, variance, entropy, 25%, 75%, 90%, 97%, and 99% values were found to be lower than the control group, and size % U value was higher. In addition, the corpus callosum area was significantly lower in the ASD compared to the controls.

CONCLUSION

According to our study, corpus callosum of patients with ASD showed differences compared to healthy controls by histogram analysis, even though they were seen as normal in brain MRI. We think that histogram analysis can be used to evaluate possibly affected areas of brain in ASD patients.

Non-severe COVID-19 complicated by cytotoxic lesions of the corpus callosum (mild encephalitis/encephalopathy with a reversible splenial lesion): a case report and literature review

BACKGROUND

Coronavirus disease 2019- (COVID-19-) associated cytotoxic lesions of the corpus callosum (CLOCCs) have been reported as a rare neurological abnormality in severe cases. Here, a case of CLOCCs in the early stages of mild COVID-19 infection during the Omicron BA.1 epidemic is reported along with a literature review.

CASE REPORT

A Japanese woman with COVID-19 presented to the emergency department with altered consciousness and cerebellar symptoms a day after fever onset. Magnetic resonance imaging (MRI) revealed a lesion with restricted diffusion in the corpus callosum. She exhibited no complications of pneumonia, her neurological symptoms resolved after two days, and after 10 days, the brain lesion was not detected on MRI.

LITERATURE REVIEW

The PubMed database was searched for case reports that met the CLOCC definition proposed by Starkey et al. The search yielded 15 COVID-19-associated cases reported as CLOCCs and 13 cases described under former terms, including mild encephalitis/encephalopathy with a reversible splenial lesion. Adult cases with a documented course were accompanied by pneumonia or hypoxemia, whereas pediatric cases were mostly accompanied by a multisystem inflammatory syndrome.

CONCLUSION

COVID-19-associated CLOCCs can occur, even at an early, non-severe stage. Therefore, this condition may be underdiagnosed if MRI is not performed.

Capecitabine related neurotoxicity: Clinical and radiologic features

AIM

To study the clinical and radiologic features of patients with capecitabine neurotoxicity.

METHODS

We performed a retrospective analysis and systematic review on the clinical and radiologic characteristics of all patients with capecitabine neurotoxicity reported in literature between 2003 and 2020.

RESULTS

24 cases including our patient were retrospectively analysed, with their clinical and radiologic features summarized. Their median age was 59 years old (ranges from 31 to 82 years old). Encephalopathy was the predominant clinical symptom affecting more than half (15/24, 63%) of the patients. This was followed by cerebellar ataxia (10/24, 42%). Amongst the patients who had magnetic resonance imaging(MRI) brain imaging performed, majority of them (18/23, 78%) had acute radiologic abnormalities. Leukoencephalopathy was the commonest radiologic abnormality seen in more than half of the patients (15/23,65%). Despite the preponderance of female patients in our study, there were no significant statistical differences in the clinical and radiologic features. Short term prognosis was excellent with complete resolution of neurologic symptoms observed in nearly all of the patients (22/23, 96%).

CONCLUSION

Capecitabine-related neurotoxicity is an uncommon cause of toxic encephalopathy, with a predilection for females. Clinical features are non-specific, with encephalopathy being the commonest. Prognosis remains good with timely recognition, and cessation of capecitabine. Future research looking into other pathogenic pharmacogenetic processes should be conducted for further elucidation of these associations.

A morphological study of the shape of the corpus callosum in normal, schizophrenic and bipolar patients

Abnormalities in the morphology of the corpus callosum have been found to be involved in cognitive impairments or abnormal behaviour in patients with mental disorders such as schizophrenia and bipolar disorder. The present study investigated morphological shape differences of the corpus callosum in a large cohort of 223 participants between normal, schizophrenic and bipolar patients on MRI scans, CT scans and cadaver samples. Healthy samples were compared to a mental disorder population sample to determine morphological shapes variations associated with schizophrenia and bipolar disorder. Landmark-based methodology was used to contour the corpus callosum shape that served as standard positions to allow for radial and thickness partitioning in order to determine shape variations within the specific localised anatomical sections of the corpus callosum. Shape analysis was performed using Ordinary Procrustes averaging and superimposing landmarks to define an average landmark position for the specific regions of the corpus callosum. No significant global shape differences were found between the different mental disorders. Schizophrenia and bipolar shapes differed mostly in the genu-rostrum, posterior body, isthmus and splenium. Sample group comparisons yielded significant differences between all groups and global measurement parameters and in various sub-regions. The findings of the present study suggest that the corpus callosum in schizophrenia and bipolar differs significantly compared to healthy controls, specifically in the anterior body and isthmus for schizophrenia and only in the isthmus for bipolar disorder. Shape changes in these regions may possibly, in part, be responsible for the symptoms and cognitive impairments observed in schizophrenia and bipolar disorder.

HaNDL syndrome: a reversible cerebral vasoconstriction triggered by an infection? A case report and a case-based review

Background

The syndrome of transient Headache and Neurological Deficits with cerebrospinal fluid (CSF) Lymphocytosis (HaNDL) is classified among secondary headaches attributed to “non-infectious, inflammatory intracranial disease”. Despite its classification among secondary headaches, the current definition of HaNDL does not contemplate a causal agent. Thus, the aetiology, as well as the pathogenesis of both the headache and the transient focal deficits, remains unknown.

Case presentation

We describe a 29-year-old healthy male developing episodes of thunderclap headaches associated with recurrence of hemiparesis/hemi-paraesthesia; CSF showed lymphocytosis 200/mm³ and increased albumin; brain MRI revealed widespread leptomeningeal enhancement and a non-enhancing, circular diffusion restriction in the splenium of corpus callosum. Screening for neurotropic pathogens detected Epstein-Barr (EBV) DNA in serum and CSF, interpreted as a primary EBV infection once the seroconversion of EBV nuclear antigen (EBNA) IgM to IgG was proven on follow-up. Transcranial Doppler detected, during headache, increased flow velocity in middle cerebral arteries, possibly indicating vasospasm. Oral nimodipine was administered, with prompt clinical recovery, resolution of CSF/MRI abnormalities, and normalization of flow velocities in middle cerebral arteries.

Case-based review

Although the definition of HaNDL does not contemplate a viral trigger or abnormal brain imaging, we found other literature cases of HaNDL associated with direct or indirect signs of CNS infection.

Conclusions

At least in a proportion of patients, a viral aetiology may have a role in HaNDL. Whatever the aetiology, we suggest that the pathogenic mechanism may rely on the (viral or other) agent ultimately triggering cerebral vasoconstriction, which would explain both focal symptoms and headache. Calcium channel blockers might be a therapeutic option.

MACF1, Involved in the 1p34.2p34.3 Microdeletion Syndrome, is Essential in Cortical Progenitor Polarity and Brain Integrity

1p34.2p34.3 deletion syndrome is characterized by an increased risk for autism. Microtubule Actin Crosslinking Factor 1 (MACF1) is one candidate gene for this syndrome. It is unclear, however, how MACF1 deletion is linked to brain development and neurodevelopmental deficits. Here we report on Macf1 deletion in the developing mouse cerebral cortex, focusing on radial glia polarity and morphological integrity, as these are critical factors in brain formation. We found that deleting Macf1 during cortical development resulted in double cortex/subcortical band heterotopia as well as disrupted cortical lamination. Macf1-deleted radial progenitors showed increased proliferation rates compared to control cells but failed to remain confined within their defined proliferation zone in the developing brain. The overproliferation of Macf1-deleted radial progenitors was associated with elevated cell cycle speed and re-entry. Microtubule stability and actin polymerization along the apical ventricular area were decreased in the Macf1 mutant cortex. Correspondingly, there was a disconnection between radial glial fibers and the apical and pial surfaces. Finally, we observed that Macf1-mutant mice exhibited social deficits and aberrant emotional behaviors. Together, these results suggest that MACF1 plays a critical role in cortical progenitor proliferation and localization by promoting glial fiber stabilization and polarization. Our findings may provide insights into the pathogenic mechanism underlying the 1p34.2p34.3 deletion syndrome.

Impact of chronic exposure to legacy environmental contaminants on the corpus callosum microstructure: A diffusion MRI study of Inuit adolescents

Exposure to environmental contaminants is an important public health concern for the Inuit population of northern Québec, who have been exposed to mercury (Hg), polychlorinated biphenyls (PCBs) and lead (Pb). During the last 25 years, the Nunavik Child Development Study (NCDS) birth cohort has reported adverse associations between these exposures and brain function outcomes. In the current study, we aimed to determine whether contaminant exposure is associated with alterations of the corpus callosum (CC), which plays an important role in various cognitive, motor and sensory function processes. Magnetic resonance imaging (MRI) was administered to 89 NCDS participants (mean age ± SD = 18.4 ± 1.2). Diffusion-weighted imaging was assessed to characterize the microstructure of the CC white matter in 7 structurally and functionally distinct regions of interest (ROIs) using a tractography-based segmentation approach. The following metrics were computed: fiber tract density, fractional anisotropy (FA), axial diffusivity (AD) and radial diffusivity (RD). Multiple linear regression models adjusted for sex, age, current alcohol/drug use and fish nutrients (omega-3 fatty acids and selenium) were conducted to assess the association between diffusion-weighted imaging metrics and Hg, PCB 153 and Pb concentrations obtained at birth in the cord blood and postnatally (mean values from blood samples at 11 and 18 years of age). Exposures were not associated with fiber tract density. Nor were significant associations found with cord and postnatal blood Pb concentrations for FA. However, pre- and postnatal Hg and PCB concentrations were significantly associated with higher FA of several regions of the CC, namely anterior midbody, posterior midbody, isthmus, and splenium, with the most pronounced effects observed in the splenium. FA results were mainly associated with lower RD. This study shows that exposure to Hg and PCB 153 alters the posterior microstructure of the CC, providing neuroimaging evidence of how developmental exposure to environmental chemicals can impair brain function and behavior in late adolescence.

Characterization of Glial Populations in the Aging and Remyelinating Mouse Corpus Callosum

Cells in the white matter of the adult brain have a characteristic distribution pattern in which several cells are contiguously connected to each other, making a linear array (LA) resembling pearls-on-a-string parallel to the axon axis. We have been interested in how this pattern of cell distribution changes during aging and remyelination after demyelination. In the present study, with a multiplex staining method, semi-quantitative analysis of the localization of oligodendrocyte lineage cells (oligodendrocyte progenitors, premyelinating oligodendrocytes, and mature oligodendrocytes), astrocytes, and microglia in 8-week-old (young adult) and 32-week-old (aged) corpus callosum showed that young adult cells still include immature oligodendrocytes and that LAs contain a higher proportion of microglia than isolated cells. In aged mice, premyelinating oligodendrocytes were decreased, but microglia continued to be present in the LAs. These results suggest that the presence of microglia is important for the characteristic cell localization pattern of LAs. In a cuprizone-induced demyelination model, we observed re-formation of LAs after completion of cuprizone treatment, concurrent with remyelination. These re-formed LAs again contained more microglia than the isolated cells. This finding supports the hypothesis that microglia contribute to the formation and maintenance of LAs. In addition, regardless of the distribution of cells (LAs or isolated cells), astrocytes were found to be more abundant than in the normal corpus callosum at 24 weeks after cuprizone treatment when remyelination is completed. This suggests that astrocytes are involved in maintaining the functions of remyelinated white matter.

Persistent white matter vulnerability in a mouse model of mild traumatic brain injury

Background

Following one mild traumatic brain injury (mTBI), there is a window of vulnerability during which subsequent mTBIs can cause substantially exacerbated impairments. Currently, there are no known methods to monitor, shorten or mitigate this window.

Methods

To characterize a preclinical model of this window of vulnerability, we first gave male and female mice one or two high-depth or low-depth mTBIs separated by 1, 7, or 14 days. We assessed brain white matter integrity using silver staining within the corpus callosum and optic tracts, as well as behavioural performance on the Y-maze test and visual cliff test.

Results

The injuries resulted in windows of white matter vulnerability longer than 2 weeks but produced no behavioural impairments. Notably, this window duration is substantially longer than those reported in any previous preclinical vulnerability study, despite our injury model likely being milder than the ones used in those studies. We also found that sex and impact depth differentially influenced white matter integrity in different white matter regions.

Conclusions

These results suggest that the experimental window of vulnerability following mTBI may be longer than previously reported. Additionally, this work highlights the value of including white matter damage, sex, and replicable injury models for the study of post-mTBI vulnerability and establishes important groundwork for the investigation of potential vulnerability mechanisms, biomarkers, and therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12868-022-00730-y.

Evaluating the rare cases of cortical vertigo using disconnectome mapping

In rare cases, cortical infarcts lead to vertigo. We evaluated structural and functional disconnection in patients with acute vertigo due to unilateral ischemic cortical infarcts compared to infarcts without vertigo in a similar location with a focus on the connectivity of the vestibular cortex, i.e., the parieto-opercular (retro-)insular cortex (PIVC). Using lesion maps from the ten published case reports, we computed lesion-functional connectivity networks in a set of healthy individuals from the human connectome project. The probability of lesion disconnection was evaluated by white matter disconnectome mapping. In all ten cases with rotational vertigo, disconnections of interhemispheric connections via the corpus callosum were present but were spared in lesions of the PIVC without vertigo. Further, the arcuate fascicle was affected in 90% of the lesions that led to vertigo and spared in lesions that did not lead to vertigo. The lesion-functional connectivity network included vestibulo-cerebellar hubs, the vestibular nuclei, the PIVC, the retro-insular and posterior insular cortex, the multisensory vestibular ventral intraparietal area, motion-sensitive areas (temporal area MT+ and cingulate visual sulcus) as well as hubs for ocular motor control (lateral intraparietal area, cingulate and frontal eye fields). However, this was not sufficient to differentiate between lesions with and without vertigo. Disruption of interhemispheric connections of both PIVC via the corpus callosum and intra-hemispheric disconnection via the arcuate fascicle might be the distinguishing factor between vestibular cortical network lesions that manifest with vertigo compared to those without vertigo.

The effect of Zingiber Officinale Extract on Preventing Demyelination of Corpus Callosum in a Rat Model of Multiple Sclerosis

Background

Multiple sclerosis (MS) is the most prevalent neurological disability of young adults. Anti-inflammatory drugs have relative effects on MS. The anti-inflammatory and antioxidative effects of Zingiber officinale (ginger) have been proven in some experimental and clinical investigations. The aim of this study was to evaluate the effects of ginger extract on preventing myelin degradation in a rat model of MS.

Methods

Forty nine male Wistar rats were used in this study and divided into four control groups: the normal group, cuprizone-induced group, sham group (cuprizone [CPZ] + sodium carboxymethyl cellulose [NaCMC]), standard control group (fingolimod + cuprizone), including three experimental groups of CPZ, each receiving three different doses of ginger extract: 150, 300, and 600mg/kg /kg/day.

Results

Ginger extract of 600 mg/kg prevented corpus callosum from demyelination; however, a significant difference was observed in the fingolimod group (p < 0.05). Difference in the CPZ group was quite significant (p < 0.05).

Conclusion

Treatment with ginger inhibited demyelination and alleviated remyelination of corpus callosum in rats. Therefore, it could serve as a therapeutic agent in the MS.

Altered transcallosal fiber count and volume in high-functioning adults with autism spectrum disorder

An altered pattern of information processing has been hypothesized in autism spectrum disorder (ASD), characterized by enhanced local network connectivity and reduced long-distance communication. Previous findings of impaired white matter integrity in the genu and the body of the corpus callosum already indicated reduced long-distance connectivity in patients with ASD. However, it remained unclear how this reduced white matter integrity affects the structural connectivity of the corresponding brain areas. To this end, we analyzed magnetic resonance images (MRI) from 30 participants with high-functioning ASD and 30 typically developed individuals using a global tracking approach to estimate the fiber count and volume of the transcallosal fiber tracts of the five corpus callosum subsections. A reduced fiber count and fiber volume in the anterior subsection of the corpus callosum was detected, supporting the hypothesis of reduced long-distance connectivity in ASD.

Spatial and temporal heterogeneity in the lineage progression of fine oligodendrocyte subtypes

Background

Oligodendrocytes are glial cells that support and insulate axons in the central nervous system through the production of myelin. Oligodendrocytes arise throughout embryonic and early postnatal development from oligodendrocyte precursor cells (OPCs), and recent work demonstrated that they are a transcriptional heterogeneous cell population, but the regional and functional implications of this heterogeneity are less clear. Here, we apply in situ sequencing (ISS) to simultaneously probe the expression of 124 marker genes of distinct oligodendrocyte populations, providing comprehensive maps of the corpus callosum, cingulate, motor, and somatosensory cortex in the brain, as well as gray matter (GM) and white matter (WM) regions in the spinal cord, at postnatal (P10), juvenile (P20), and young adult (P60) stages. We systematically compare the abundances of these populations and investigate the neighboring preference of distinct oligodendrocyte populations.

Results

We observed that oligodendrocyte lineage progression is more advanced in the juvenile spinal cord compared to the brain, corroborating with previous studies. We found myelination still ongoing in the adult corpus callosum while it was more advanced in the cortex. Interestingly, we also observed a lateral-to-medial gradient of oligodendrocyte lineage progression in the juvenile cortex, which could be linked to arealization, as well as a deep-to-superficial gradient with mature oligodendrocytes preferentially accumulating in the deeper layers of the cortex. The ISS experiments also exposed differences in abundances and population dynamics over time between GM and WM regions in the brain and spinal cord, indicating regional differences within GM and WM, and we found that neighboring preferences of some oligodendroglia populations are altered from the juvenile to the adult CNS.

Conclusions

Overall, our ISS experiments reveal spatial heterogeneity of oligodendrocyte lineage progression in the brain and spinal cord and uncover differences in the timing of oligodendrocyte differentiation and myelination, which could be relevant to further investigate functional heterogeneity of oligodendroglia, especially in the context of injury or disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01325-z.

Psychosocial Risk Factors for Alzheimer's Disease in Patients with Down Syndrome and Their Association with Brain Changes: A Narrative Review

Several recent epidemiological studies attempted to identify risk factors for Alzheimer’s disease. Age, family history, genetic factors (APOE genotype, trisomy 21), physical activity, and a low level of schooling are significant risk factors. In this review, we summarize the known psychosocial risk factors for the development of Alzheimer’s disease in patients with Down syndrome and their association with neuroanatomical changes in the brains of people with Down syndrome. We completed a comprehensive review of the literature on PubMed, Google Scholar, and Web of Science about psychosocial risk factors for Alzheimer’s disease, for Alzheimer’s disease in Down syndrome, and Alzheimer’s disease in Down syndrome and their association with neuroanatomical changes in the brains of people with Down syndrome. Alzheimer’s disease causes early pathological changes in individuals with Down syndrome, especially in the hippocampus and corpus callosum. People with Down syndrome living with dementia showed reduced volumes of brain areas affected by Alzheimer’s disease as the hippocampus and corpus callosum in association with cognitive decline. These changes occur with increasing age, and the presence or absence of psychosocial risk factors impacts the degree of cognitive function. Correlating Alzheimer’s disease biomarkers in Down syndrome and cognitive function scores while considering the effect of psychosocial risk factors helps us identify the mechanisms leading to Alzheimer’s disease at an early age. Also, this approach enables us to create more sensitive and relevant clinical, memory, and reasoning assessments for people with Down syndrome.

Free water diffusion MRI and executive function with a speed component in healthy aging

Extracellular free water (FW) increases are suggested to better provide pathophysiological information in brain aging than conventional biomarkers such as fractional anisotropy. The aim of the present study was to determine the relationship between conventional biomarkers, FW in white matter hyperintensities (WMH), FW in normal appearing white matter (NAWM) and in white matter tracts and executive functions (EF) with a speed component in elderly persons.

We examined 226 healthy elderly participants (median age 69.83 years, IQR: 56.99–74.42) who underwent brain MRI and neuropsychological examination. FW in WMH and in NAWM as well as FW corrected diffusion metrics and measures derived from conventional MRI (white matter hyperintensities, brain volume, lacunes) were used in partial correlation (adjusted for age) to assess their correlation with EF with a speed component. Random forest analysis was used to assess the relative importance of these variables as determinants. Lastly, linear regression analyses of FW in white matter tracts corrected for risk factors of cognitive and white matter deterioration, were used to examine the role of specific tracts on EF with a speed component, which were then ranked with random forest regression.

Partial correlation analyses revealed that almost all imaging metrics showed a significant association with EF with a speed component (r = −0.213 – 0.266). Random forest regression highlighted FW in WMH and in NAWM as most important among all diffusion and structural MRI metrics. The fornix (R²=0.421, p = 0.018) and the corpus callosum (genu (R² = 0.418, p = 0.021), prefrontal (R² = 0.416, p = 0.026), premotor (R² = 0.418, p = 0.021)) were associated with EF with a speed component in tract based regression analyses and had highest variables importance.

In a normal aging population FW in WMH and NAWM is more closely related to EF with a speed component than standard DTI and brain structural measures. Higher amounts of FW in the fornix and the frontal part of the corpus callosum leads to deteriorating EF with a speed component.

Primary CNS lymphoma of the corpus callosum: presentation and neurocognitive outcomes

INTRODUCTION

The corpus callosum (CC) is frequently involved in primary central nervous system lymphomas (PCNSLs). In this cohort study, we described the neurocognition of patients with PCNSL-CC and its posttherapeutic evolution.

METHODS

Immunocompetent patients with PCNSL-CC were identified retrospectively at the Pitié-Salpêtrière Hospital. We described their clinical presentation. Neuropsychological test scores (MMSE; digit spans; Free and Cued Selective Reminding Test; Image Oral Naming Test; Frontal Assessment Battery; Trail Making Test; Stroop and verbal fluency tests; Rey's Complex Figure test) and factors impacting them were analyzed.

RESULTS

Twenty-seven patients were included (median age: 67 years, median Karnofsky Performance Status: 70); cognitive impairment and balance disorders were present in 74% and 59%, respectively. At diagnosis, neuropsychological test results were abnormal for global cognitive efficiency (63% of patients), memory (33-80% depending on the test) and executive functions (44-100%). Results for visuospatial and language tests were normal. All patients received high-dose methotrexate-based polychemotherapy, followed in one patient by whole-brain radiotherapy; 67% of patients achieved complete response (CR). With a median follow-up of 48 months (range 6-156), patients in CR had persistent abnormal test results for global cognitive efficiency in 17%, executive function in 18-60%, depending on the test, and memory in 40-60%. Splenium location and age ≥ 60 years were significantly associated with worse episodic memory scores throughout the follow-up.

CONCLUSIONS

PCNSL-CC is associated with frequent cognitive dysfunctions, especially memory impairment, which may recover only partially despite CR and warrant specific rehabilitation. Older age (≥ 60) and splenium location are associated with worse neurocognitive outcomes.

Generalisation of continuous time random walk to anomalous diffusion MRI models with an age-related evaluation of human corpus callosum

Diffusion MRI measures of the human brain provide key insight into microstructural variations across individuals and into the impact of central nervous system diseases and disorders. One approach to extract information from diffusion signals has been to use biologically relevant analytical models to link millimetre scale diffusion MRI measures with microscale influences. The other approach has been to represent diffusion as an anomalous transport process and infer microstructural information from the different anomalous diffusion equation parameters. In this study, we investigated how parameters of various anomalous diffusion models vary with age in the human brain white matter, particularly focusing on the corpus callosum. We first unified several established anomalous diffusion models (the super-diffusion, sub-diffusion, quasi-diffusion and fractional Bloch-Torrey models) under the continuous time random walk modelling framework. This unification allows a consistent parameter fitting strategy to be applied from which meaningful model parameter comparisons can be made. We then provided a novel way to derive the diffusional kurtosis imaging (DKI) model, which is shown to be a degree two approximation of the sub-diffusion model. This link between the DKI and sub-diffusion models led to a new robust technique for generating maps of kurtosis and diffusivity using the sub-diffusion parameters β_SUB and D_SUB. Superior tissue contrast is achieved in kurtosis maps based on the sub-diffusion model. 7T diffusion weighted MRI data for 65 healthy participants in the age range 19-78 years was used in this study. Results revealed that anomalous diffusion model parameters α and β have shown consistent positive correlation with age in the corpus callosum, indicating α and β are sensitive to tissue microstructural changes in ageing.

Individual variability in the nonlinear development of the corpus callosum during infancy and toddlerhood: a longitudinal MRI analysis

The human brain spends several years bootstrapping itself through intrinsic and extrinsic modulation, thus gradually developing both spatial organization and functions. Based on previous studies on developmental patterns and inter-individual variability of the corpus callosum (CC), we hypothesized that inherent variations of CC shape among infants emerge, depending on the position within the CC, along the developmental timeline. Here we used longitudinal magnetic resonance imaging data from infancy to toddlerhood and investigated the area, thickness, and shape of the midsagittal plane of the CC by applying multilevel modeling. The shape characteristics were extracted using the Procrustes method. We found nonlinearity, region-dependency, and inter-individual variability, as well as intra-individual consistencies, in CC development. Overall, the growth rate is faster in the first year than in the second year, and the trajectory differs between infants; the direction of CC formation in individual infants was determined within six months and maintained to two years. The anterior and posterior subregions increase in area and thickness faster than other subregions. Moreover, we clarified that the growth rate of the middle part of the CC is faster in the second year than in the first year in some individuals. Since the division of regions exhibiting different tendencies coincides with previously reported divisions based on the diameter of axons that make up the region, our results suggest that subregion-dependent individual variability occurs due to the increase in the diameter of the axon caliber, myelination partly due to experience and axon elimination during the early developmental period.

Statistical shape analyses of corpus callosum changes at preoperative and postoperative scaphocephaly patients

PURPOSE

Scaphocephaly is the premature closure of the sagittal suture. The treatment strategies mainly focus on correcting the shape of the head, but there are very limited studies examining changes in brain structure. This study aimed to investigate shape differences in the shape of corpus callosum regarding the pre-treatment and post-treatment term at scaphocephaly patients.

METHODS

Cranium shape data were collected from the two-dimensional digital images. The generalized Procrustes analysis was used to obtain mean shapes in the pre- and postoperative phases. The shape deformation of the corpus callosum from the pre- to postoperative phases was evaluated using the thin plate spline method.

RESULTS

There is an enlargement of the splenium part of corpus callosum in the late group. In the early group, corpus callosum genu and body enlargement were observed in the postoperative period compared to the preoperative period, followed by a narrowing of the isthmus region.

CONCLUSION

This study showed structural deformations in the corpus callosum in scaphocephaly patients using head shape with the landmark-based geometric morphometric method by taking into consideration the topographic distribution. An enlargement at the splenium part of corpus callosum exposes after the cranial vault expansion depending on time.

A rare case of bilateral vitreoretinopathy of Aicardi syndrome

Purpose

To report a rare case of Aicardi syndrome presenting with concurrent peripheral retina nonperfusion with 360-degree neovascularization in the right eye and stalk tissue with a peripapillary fibrovascular membrane and tractional retinal detachment (TRD) in the left eye.

Observations

A one-month-old girl was referred for an ophthalmic evaluation to confirm the diagnosis of Aicardi syndrome due to abnormal brain magnetic resonance imaging. A 360-degree circumferential peripheral avascular retina with extensive neovascularization was present in the right eye. Stalk tissue with fibrovascular proliferation causing TRD was found in the left fundus. The retina of the right eye became quiescent after completing peripheral laser photocoagulation. The detached retina in the left eye was flattened, and the peripapillary chorioretinal lacunae became visible one year after surgical removal of the traction. In addition, the axial length growth of the left eye regained.

Conclusion and importance

This is a rare case of Aicardi syndrome with concurrent peripapillary fibrovascular traction in one eye and peripheral retina nonperfusion in the other eye. Surgical intervention is vital not only for removing the traction and flattening the retina but also for promoting continual growth of the eyeball.

Morphometry of Corpus Callosum in South Indian Population

Background:

The corpus callosum (CC) is a connecting bridge between two cerebral hemispheres and helps in interhemispheric integration of information.

Purpose:

The primary objective of the study is to explain the topographical position of CC in relation to the brain in the South Indian population, contributing to the reference values of measurements of CC, which helps in planning surgical interventions. Also, the reference values help in cross-referencing with other populations and ethnic group.

Methods:

In the study, 40 formalin fixed, full brain specimens were cut in midsagittal plane and CC was measured along with its relation to the brain. The major diameters considered were longitudinal dimension of corpus callosum (LC), distance of CC from frontal pole to genu (AS), distance of CC occipital pole to splenium (PS), and longitudinal dimension of brain (LB) from frontal pole to occipital pole.

Results:

Pearson’s ratio showed a positive correlation between LB and PS (0.61), and also between LB and LC (0.59). The ratio of LC/LB was 0.45 and LC/CD was 0.69, which are stable in all brains studied.

Conclusion:

The study concludes that CC maintains a stable proportion with its parts (genu, rostrum, body, and splenium) and with the horizontal dimension of the brain. Further, measured values help in cross-referencing with other population.

Corpus Callosum Volumes in Children with Autism Spectrum Disorders: Sex-Associated Differences

This study aimed to analyze the relationship between sex and corpus callosum (CC) volume in children with autism spectrum disorders (ASD) aged 2-4 years. This prospective study included 50 children with ASD and 50 typically developing (TD) children aged 2-4 years. Midsagittal slices of the CCs of the participants were divided into five subregions using FreeSurfer software. The PMCC, AMCC and TCC volumes were significantly higher in ASD participants than in TD participants, and results were significant in females with ASD rather than in males with ASD (all P < 0.05). In toddlers with ASD, the CC volumes were increased and more pronounced in females than in males. This could be due to overgrowth of axons or/and axonal pruning disorders.

Biochemical Alterations in White Matter Tracts of the Aging Mouse Brain Revealed by FTIR Spectroscopy Imaging

White matter degeneration in the central nervous system (CNS) has been correlated with a decline in cognitive function during aging. Ultrastructural examination of the aging human brain shows a loss of myelin, yet little is known about molecular and biochemical changes that lead to myelin degeneration. In this study, we investigate myelination across the lifespan in C57BL/6 mice using electron microscopy and Fourier transform infrared (FTIR) spectroscopic imaging to better understand the relationship between structural and biochemical changes in CNS white matter tracts. A decrease in the number of myelinated axons was associated with altered lipid profiles in the corpus callosum of aged mice. FTIR spectroscopic imaging revealed alterations in functional groups associated with phospholipids, including the lipid acyl, lipid ester and phosphate vibrations. Biochemical changes in white matter were observed prior to structural changes and most predominant in the anterior regions of the corpus callosum. This was supported by biochemical analysis of fatty acid composition that demonstrated an overall trend towards increased monounsaturated fatty acids and decreased polyunsaturated fatty acids with age. To further explore the molecular mechanisms underlying these biochemical alterations, gene expression profiles of lipid metabolism and oxidative stress pathways were investigated. A decrease in the expression of several genes involved in glutathione metabolism suggests that oxidative damage to lipids may contribute to age-related white matter degeneration.

Combined use of multimodal techniques for the resection of glioblastoma involving corpus callosum

PURPOSE

To compare the multimodal techniques (including neuronavigation, intraoperative MRI [iMRI], and neuromonitoring [IONM]) and conventional approach (only guided by neuronavigation) in removing glioblastoma (GBM) with corpus callosum (CC) involvement (ccGBM), their effectiveness and safety were analyzed and compared.

METHODS

Electronic medical records were retrospectively reviewed for ccGBM cases treated in our hospital between January 2016 and July 2020. Patient demographics, tumor characteristics, clinical outcomes, extent of resection (EOR), progression-free survival (PFS), and overall survival (OS) were obtained and compared between the multimodal group (used multimodal techniques) and the conventional group (only used neuronavigation). Both groups only included patients that had maximal safe resection (not biopsy). Postoperative radiochemotherapy was also performed or not. Univariate and multivariate analyses were performed to identify significant prognostic factors and optimal EOR threshold.

RESULTS

Finally 56 cases of the multimodal group and 21 cases of the conventional group were included. The multimodal group achieved a higher median EOR (100% versus 96.1%, P = 0.036) and gross total resection rate (60.7% versus 33.3%, P = 0.032) and a lower rate of permanent motor deficits (5.4% versus 23.8%, P = 0.052) than the conventional approach. The multimodal group had the longer median PFS (10.9 versus 7.0 months, P = 0.023) and OS (16.1 versus 11.6 months, P = 0.044) than the conventional group. Postoperative language and cognitive function were similar between the two groups. In multivariate analysis, a higher EOR, radiotherapy, and longer cycles of temozolomide chemotherapy were positive prognostic factors for survival of ccGBM. An optimal EOR threshold of 92% was found to significantly benefit the PFS (HR = 0.51, P = 0.036) and OS (HR = 0.49, P = 0.025) of ccGBM.

CONCLUSION

Combined use of multimodal techniques can optimize the safe removal of ccGBM. Aggressive resection of EOR > 92% using multimodal techniques combined with postoperative radiochemotherapy should be suggested for ccGBM.

Inflammatory cytokines and callosal white matter microstructure in adolescents

Adolescent depression is characterized by heightened inflammation and altered connectivity of fronto-cingulate-limbic tracts, including the genu of the corpus callosum (CCG) and the uncinate fasciculus (UF). No studies, however, have yet examined the association between inflammation, measured by peripheral levels of cytokines, and white matter connectivity of fronto-cingulate-limbic tracts in adolescents. Here, 56 depressed adolescents (32 females, 3 non-binary; 16.23 ± 1.28 years) and 19 controls (10 females; 15.72 ± 1.17 years) completed a diffusion-weighted MRI scan at 3 Tesla. We conducted deterministic tractography to segment bilateral corpus callosum (genu and splenium) and UF and computed mean fractional anisotropy (FA) in each tract. A subset of participants (43 depressed and 17 healthy controls) also provided dried blood spot samples from which we assayed interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-ɑ) using a Luminex multiplex array. Depressed participants did not differ from controls in FA of the corpus callosum or UF (all FDR-corrected ps > 0.056) but exhibited higher levels of inflammation than did controls (IL-6: β = 0.91, FDR-corrected p = 0.006; TNF-α: β = 0.76, FDR-corrected p = 0.006). Although diagnostic group did not moderate the associations between inflammatory cytokines and FA in the CCG and UF, across both groups, greater peripheral inflammation was associated with lower FA in the CCG (IL-6: β = -0.38; FDR-corrected p = 0.044; TNF-ɑ: β = -0.41, FDR-corrected p = 0.044). This study is the first to examine associations between peripheral inflammation and white matter microstructure of fronto-cingulate-limbic tracts in depressed and nondepressed adolescents. Future mechanistic studies are needed to confirm our findings; nevertheless, our results suggest that heightened inflammation is an important component of neurophenotypes that are relevant to adolescent depression.