Ceroid lipofuscinosis type 2 disease: Effective presymptomatic therapy-Oldest case of a presymptomatic enzyme therapy.

Neuronal ceroid lipofuscinosis type 2 (CLN2) disease is a rare, lysosomal storage disorder that causes pediatric onset neurodegenerative disease. It is characterized by mutations in the TPP1 gene. Symptoms begin between 2 and 4 years of age with loss of previously acquired motor, cognitive, and language abilities. Cerliponase alfa, a recombinant human TPP1 enzyme, is the only approved therapy. We report the first presymptomatic cerliponase alfa intraventricular treatment in a familial case of CLN2 related to a classical TPP1 variant. Sister 1 presented with motor, cognitive, and language decline and progressive myoclonic epilepsy since the age of 3 years, evolved with severe diffuse encephalopathy, received no specific treatment, and died at 11 years. Sister 2 had a CLN2 presymptomatic diagnosis and has been treated with cerliponase since she was 12 months old. She is now 6 years 8 months and has no CLN2 symptom except one generalized seizure 1 year ago. No serious adverse event has occurred. Repeated Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition standardized index scores are heterogeneous in the extremely low to low average ranges. Mean length of utterances, a global index of sentence complexity, showed a delay, but a gradual improvement. The reported case enhances the major contribution of presymptomatic diagnosis and significant middle-term treatment benefit for patients with CLN2.

Long-term weight gain in children with craniopharyngioma.

OBJECTIVE: Adamantinomatous craniopharyngioma mainly affects children. Excessive weight gain is a major long-term complication. The primary objective of this study was to assess long-term weight changes in children treated for craniopharyngioma. The secondary objectives were to identify risk factors for excessive weight gain and to look for associations with hypothalamic damage by the tumour or treatment. DESIGN: Single-centre retrospective cohort study. METHOD: Children managed for craniopharyngioma at our centre between 1990 and 2019 were included. The body mass index (BMI) standard deviation scores (SDS) at baseline and at last follow-up were compared. Univariate and multivariate analyses were performed in order to identify variables associated with the long-term BMI-SDS variation. RESULTS: The 108 patients had a mean follow-up of 10.4 years. The mean BMI-SDS increase over time was 2.11 (P < .001) overall, 1.21 (P < .001) in the group without hypothalamic involvement by the tumour, and 1.95 (P < .001) in the group managed using intended hypothalamus-sparing surgery. The absence of hypothalamic involvement by the tumour or treatment was significantly associated with less weight gain (P = .046 and P < .01, respectively). After adjustment, factors associated with a BMI-SDS change greater than 2 were female sex (P = .023), tumour involving the hypothalamus (P = .04), and higher baseline BMI (P < .001). CONCLUSION: Clinically significant weight gain occurred in nearly all children treated for craniopharyngioma, including those whose hypothalamus was spared by the tumour and intentionally by treatment. However, hypothalamus integrity was associated with less weight gain. Despite hypothalamus-sparing strategies, hypothalamic obesity remains a major concern, indicating a need for novel treatment approaches.

Brain 18 F-FDG PET reveals cortico-subcortical hypermetabolic dysfunction in juvenile neuropsychiatric systemic lupus erythematosus.

BACKGROUND: In juvenile systemic lupus erythematosus (j-SLE) with neuropsychiatric (NP) symptoms, there is a lack of diagnostic biomarkers. Thus, we study whether PET-FDG may identify any metabolic dysfunction in j-NPSLE. METHODS: A total of 19 18FDG-PET exams were consecutively performed using PET-MRI system in 11 non-sedated patients presenting with j-NPSLE (11-18y) for less than 18 months (m) and without any significant lesion at MRI. Psychiatric symptoms were scored from 0 (none) to 3 (severe) at PET time. PET images were visually analyzed and voxel-based analyses of cerebral glucose metabolism were performed using statistical parametric mapping (spm) with an age-matched control group, at threshold set > 50 voxels using both p < 0.001 uncorrected (unc.) and p < 0.05 corrected family wise error (FWE). RESULTS: Patients exhibited mainly psychiatric symptoms, with diffuse inflammatory j-NPSLE. First PET (n = 11) was performed at a mean of 15y of age, second/third PET (n = 7/n = 1) 6 to 19 m later. PET individual analysis detected focal bilateral anomalies in 13/19 exams visually but 19/19 using spm (unc.), mostly hypermetabolic areas (18/19). A total of 15% of hypermetabolic areas identified by spm had been missed visually. PET group analysis (n = 19) did not identify any hypometabolic area, but a large bilateral cortico-subcortical hypermetabolic pattern including, by statistical decreasing order (unc.), thalamus, subthalamic brainstem, cerebellum (vermis and cortex), basal ganglia, visual, temporal and frontal cortices. Mostly the subcortical hypermetabolism survived to FWE analysis, being most intense and extensive (51% of total volume) in thalamus and subthalamus brainstem. Hypermetabolism was strictly subcortical in the most severe NP subgroup (n = 8, scores 2-3) whereas it also extended to cerebral cortex, mostly visual, in the less severe subgroup (n = 11, scores 0-1), but difference was not significant. Longitudinal visual analysis was inconclusive due to clinical heterogeneity. CONCLUSIONS: j-NPSLE patients showed a robust bilateral cortico-subcortical hypermetabolic network, focused subcortically, particularly in thalamus, proportionally to psychiatric features severity. Further studies with larger, but homogeneous, cohorts are needed to determine the sensitivity and specificity of this dysfunctional pattern as a potential biomarker in diffuse inflammatory j-NPSLE with normal brain MRI.

CNS tumors with PLAGL1-fusion: beyond ZFTA and YAP1 in the genetic spectrum of supratentorial ependymomas.

A novel methylation class, "neuroepithelial tumor, with PLAGL1 fusion" (NET-PLAGL1), has recently been described, based on epigenetic features, as a supratentorial pediatric brain tumor with recurrent histopathological features suggesting an ependymal differentiation. Because of the recent identification of this neoplastic entity, few histopathological, radiological and clinical data are available. Herein, we present a detailed series of nine cases of PLAGL1-fused supratentorial tumors, reclassified from a series of supratentorial ependymomas, non-ZFTA/non-YAP1 fusion-positive and subependymomas of the young. This study included extensive clinical, radiological, histopathological, ultrastructural, immunohistochemical, genetic and epigenetic (DNA methylation profiling) data for characterization. An important aim of this work was to evaluate the sensitivity and specificity of a novel fluorescent in situ hybridization (FISH) targeting the PLAGL1 gene. Using histopathology, immunohistochemistry and electron microscopy, we confirmed the ependymal differentiation of this new neoplastic entity. Indeed, the cases histopathologically presented as "mixed subependymomas-ependymomas" with well-circumscribed tumors exhibiting a diffuse immunoreactivity for GFAP, without expression of Olig2 or SOX10. Ultrastructurally, they also harbored features reminiscent of ependymal differentiation, such as cilia. Different gene partners were fused with PLAGL1: FOXO1, EWSR1 and for the first time MAML2. The PLAGL1 FISH presented a 100% sensitivity and specificity according to RNA sequencing and DNA methylation profiling results. This cohort of supratentorial PLAGL1-fused tumors highlights: 1/ the ependymal cell origin of this new neoplastic entity; 2/ benefit of looking for a PLAGL1 fusion in supratentorial cases of non-ZFTA/non-YAP1 ependymomas; and 3/ the usefulness of PLAGL1 FISH.

A comprehensive histomolecular characterization of meningioangiomatosis: Further evidence for a precursor neoplastic lesion.

Meningioangiomatosis (MAM) remains a poorly understood lesion responsible for epileptic disease. In the past, MAM was primarily described in the context of neurofibromatosis type 2 before being mainly reported sporadically. Moreover, the malformative or tumoral nature is still debated. Because a subset of MAM are associated with meningiomas, some authors argue that MAM corresponds to an infiltration pattern of these tumors. For these reasons, MAM has not been added to the World Health Organization (WHO) Classification of Central Nervous System Tumors as a specific entity. In the present study, we characterized a series of pure MAM (n = 7) and MAM associated with meningiomas (n = 4) using histopathology, immunohistochemistry, genetic (fluorescent in situ and DNA sequencing analyses), and epigenetic (DNA-methylation profiling) data. We evidenced two distinct morphological patterns: MAM with a fibroblastic-like pattern having few lesional cells, and MAM with a more cellular pattern. A subset was associated with the genetic alterations previously reported in meningiomas (such as a KMT2C mutation and a hemizygous deletion of chromosome 22q including the NF2 gene). The DNA-methylation profile, using a t-distributed stochastic neighbor embedding analysis, evidenced that MAM (pure or associated with meningiomas) clustered in a separate group from pediatric meningiomas. The present results seem to suggest that MAM represents a neoplastic lesion and encourage the further study of similar additional series so that it may be included in a future WHO classification.

Clinical, Neuroimaging, and Metabolic Footprint of the Neurodevelopmental Disorder Caused by Monoallelic HK1 Variants.

Background and Objectives: Hexokinase 1 (encoded by HK1) catalyzes the first step of glycolysis, the adenosine triphosphate-dependent phosphorylation of glucose to glucose-6-phosphate. Monoallelic HK1 variants causing a neurodevelopmental disorder (NDD) have been reported in 12 individuals. Methods: We investigated clinical phenotypes, brain MRIs, and the CSF of 15 previously unpublished individuals with monoallelic HK1 variants and an NDD phenotype. Results: All individuals had recurrent variants likely causing gain-of-function, representing mutational hot spots. Eight individuals (c.1370C>T) had a developmental and epileptic encephalopathy with infantile onset and virtually no development. Of the other 7 individuals (n = 6: c.1334C>T; n = 1: c.1240G>A), 3 adults showed a biphasic course of disease with a mild static encephalopathy since early childhood and an unanticipated progressive deterioration with, e.g., movement disorder, psychiatric disease, and stroke-like episodes, epilepsy, starting in adulthood. Individuals who clinically presented in the first months of life had (near)-normal initial neuroimaging and severe cerebral atrophy during follow-up. In older children and adults, we noted progressive involvement of basal ganglia including Leigh-like MRI patterns and cerebellar atrophy, with remarkable intraindividual variability. The CSF glucose and the CSF/blood glucose ratio were below the 5th percentile of normal in almost all CSF samples, while blood glucose was unremarkable. This biomarker profile resembles glucose transporter type 1 deficiency syndrome; however, in HK1-related NDD, CSF lactate was significantly increased in all patients resulting in a substantially different biomarker profile. Discussion: Genotype-phenotype correlations appear to exist for HK1 variants and can aid in counseling. A CSF biomarker profile with low glucose, low CSF/blood glucose, and high CSF lactate may point toward monoallelic HK1 variants causing an NDD. This can help in variant interpretation and may aid in understanding the pathomechanism. We hypothesize that progressive intoxication and/or ongoing energy deficiency lead to the clinical phenotypes and progressive neuroimaging findings.

Vitamin deficiencies in children: Lessons from clinical and neuroimaging findings.

BACKGROUND AND AIMS: Water-soluble vitamins play an essential coenzyme role in the nervous system. Acquired vitamin deficiencies are easily treatable, however, without treatment, they can lead to irreversible complications. This study aimed to provide clinical, laboratory parameters and neuroimaging data on vitamin deficiencies in an attempt to facilitate early diagnosis and prompt supplementation. METHODS: From July 1998 to July 2023, patients at Necker-Enfants-Malades Hospital presenting with acute neurological symptoms attributed to acquired vitamin deficiency were included. Clinical data were extracted from Dr Warehouse database. Neuroimaging, biochemical and electrophysiological data were reviewed. RESULTS: Patients with vitamin B1 deficiency exhibited abnormal eye movements (n = 4/4), fluctuations in consciousness (n = 3/4), and ataxia (n = 3/4). Brain MRI showed alterations of fourth ventricle region (n = 4/4), periaqueductal region (n = 4/4), tectum (n = 3/4), and median thalami (n = 3/4). Patients with vitamin B2 deficiency presented with early onset hypotonia (n = 3/4), hyperlactatemia (n = 4/4), and hyperammonemia (n = 4/4). Plasma acylcarnitines revealed a multiple acyl-coA dehydrogenase deficiency-like profile (n = 4/4). In vitamin B12 deficiency, young children presented with developmental delay (n = 7/7) and older children with proprioceptive ataxia (n = 3/3). Brain MRI revealed atrophy (n = 7/7) and spinal MRI hyperintensity in posterior cervical columns (n = 3/3). Metabolic findings showed elevated methylmalonic acid (n = 6/7) and hyperhomocysteinemia (n = 6/7). Patients with vitamin C deficiency exhibited gait disturbances and muscle weakness (n = 2/2). CONCLUSIONS: Acquired vitamin deficiencies may display reversible clinical symptoms mimicking inherited metabolic disorders. Some situations raise suspicion for diagnosis: concordant clinical presentation, suggestive neuroimaging findings, and/or biochemical evidence. Any acute neurological condition should be treated without waiting for definitive biochemical confirmation.

A loss of function mutation in CLDN25 causing Pelizaeus-Merzbacher-like leukodystrophy.

Claudin-25 (CLDN-25), also known as Claudin containing domain 1, is an uncharacterized claudin family member. It has less conserved amino acid sequences when compared to other claudins. It also has a very broad tissue expression profile and there is currently a lack of functional information from murine knockout models. Here, we report a de novo missense heterozygous variant in CLDN25 (c. 745G>C, p. A249P) found in a patient diagnosed with Pelizaeus-Merzbacher-like leukodystrophy and presenting with symptoms such as delayed motor development, several episodes of tonic absent seizures and generalized dystonia. The variant protein does not localize to the cell-cell borders where it would normally be expected to be expressed. Amino acid position 249 is located 4 amino acids from the C-terminal end of the protein where most claudin family members have a conserved binding motif for the key scaffolding protein ZO-1. However, CLDN-25 does not contain this motif. Here, we show that the C-terminal end of CLDN-25 is required for its junctional localization in a ZO-1 independent manner. The A249P mutant protein as well as a deletion mutant lacking its last 5 C-terminal amino acids also failed to localize to the cell-cell border in vitro. Intriguingly, cellular knockout of CLDN25, in vitro, appeared to increase the integrity of the tight junction between 2 contacting cells, while driving highly unusual increased movement of solutes between cells. We propose that the barrier function of CLDN-25 is akin to a decoy claudin, whereby decreasing its expression in "leaky" epithelial cells and endothelial cells will drive dynamic changes in the adhesion and interaction capacity of cell-cell contact points. While it remains unclear how this de novo CLDN-25 mutant induces leukodystrophy, our findings strongly suggest that this mutation induces haploinsufficiency of CLDN-25. Elucidating the function of this uncharacterized claudin protein will lead to a better understanding of the role of claudin proteins in health and disease.

De novo variants in DENND5B cause a neurodevelopmental disorder.

The Rab family of guanosine triphosphatases (GTPases) includes key regulators of intracellular transport and membrane trafficking targeting specific steps in exocytic, endocytic, and recycling pathways. DENND5B (Rab6-interacting Protein 1B-like protein, R6IP1B) is the longest isoform of DENND5, an evolutionarily conserved DENN domain-containing guanine nucleotide exchange factor (GEF) that is highly expressed in the brain. Through exome sequencing and international matchmaking platforms, we identified five de novo variants in DENND5B in a cohort of five unrelated individuals with neurodevelopmental phenotypes featuring cognitive impairment, dysmorphism, abnormal behavior, variable epilepsy, white matter abnormalities, and cortical gyration defects. We used biochemical assays and confocal microscopy to assess the impact of DENND5B variants on protein accumulation and distribution. Then, exploiting fluorescent lipid cargoes coupled to high-content imaging and analysis in living cells, we investigated whether DENND5B variants affected the dynamics of vesicle-mediated intracellular transport of specific cargoes. We further generated an in silico model to investigate the consequences of DENND5B variants on the DENND5B-RAB39A interaction. Biochemical analysis showed decreased protein levels of DENND5B mutants in various cell types. Functional investigation of DENND5B variants revealed defective intracellular vesicle trafficking, with significant impairment of lipid uptake and distribution. Although none of the variants affected the DENND5B-RAB39A interface, all were predicted to disrupt protein folding. Overall, our findings indicate that DENND5B variants perturb intracellular membrane trafficking pathways and cause a complex neurodevelopmental syndrome with variable epilepsy and white matter involvement.

"Hemispheric pilocytic astrocytoma" revisited: A comprehensive clinicopathological and molecular series emphasizing their overlap with other glioneuronal tumors.

Pilocytic astrocytomas (PA) typically exhibit distinct clinical, radiological, histopathological, and genetic features. DNA-methylation profiling distinguishes PA according to their location (infratentorial, midline, hemispheric, or spinal). In the hemispheric location, distinguishing PA from glioneuronal tumors remains a common diagnostic challenge for neuropathologists. Furthermore, the current version of the DKFZ classifier seems to have difficulty separating them from gangliogliomas. In this study, after central radiological review, we identified a histopathologically defined set of PA (histPA, n = 11) and a cohort of DNA-methylation defined PA (mcPA, n = 11). Nine out of the 11 histPA matched the methylation class of hemispheric PA, whereas 2 cases were classified at the end of the study as dysembryoplastic neuroepithelial tumors. Similarly, the mcPA cohort contained tumors mainly classified as PA (7/11), but 4 cases were classified as glioneuronal. The analysis of the 16 tumors with an integrated diagnosis of PA revealed that they affect mainly children with a wide spectrum of radiological, histopathological (i.e. a predominantly diffuse growth pattern), and genetic characteristics (large range of mitogen-activated protein kinase alterations). Based on these results, we consider hemispheric PA to be different from their counterparts in other locations and to overlap with other glioneuronal tumors, reinforcing the necessity of interpreting all data to obtain an accurate diagnosis.

CNS erythroblastic sarcoma: a potential emerging pediatric tumor type characterized by NFIA::RUNX1T1/3 fusions.

Erythroblastic sarcoma (ES) (previously called chloroma or granulocytic sarcoma) are rare hematological neoplams characterized by the proliferation of myeloid blasts at extramedullary sites, and primarily involve the skin and soft tissue of middle-aged adults. ES may be concomitant with or secondary to myeloid neoplasms (mostly acute myeloid leukemia (AML)) or in isolated cases (de novo) without infiltration of the bone marrow by blasts. ES share cytogenetic and molecular abnormalities with AML, including RUNX1T1 fusions. Some of these alterations seem to be correlated with particular sites of involvement. Herein, we report an isolated erythroblastic sarcoma with NFIA::RUNX1T1 located in the central nervous system (CNS) of a 3-year-old boy. Recently, two pediatric cases of CNS MS with complete molecular characterization have been documented. Like the current case, they concerned infants (2 and 3 years-old) presenting a brain tumor (pineal involvement) with leptomeningeal dissemination. Both cases also harbored a NFIA::RUNX1T3 fusion. ES constitutes a diagnostic challenge for neuropathologists because it does not express differentiation markers such as CD45, and may express CD99 which could be confused with CNS Ewing sarcoma. CD43 is the earliest pan-hematopoietic marker and CD45 is not expressed by erythroid lineage cells. E-cadherin (also a marker of erythroid precursors) and CD117 (expressed on the surface of erythroid lineage cells) constitute other immunhistochemical hallmarks of ES. The prognosis of patients with ES is similar to that of other patients with AML but de novo forms seem to have a poorer prognosis, like the current case. To conclude, pediatric ES with NFIA::RUNX1T1/3 fusions seem to have a tropism for the CNS and thus constitute a potential pitfall for neuropathologists. Due to the absence of circulating blasts and a DNA-methylation signature, the diagnosis must currently be made by highlighting the translocation and expression of erythroid markers.

Fluid suppression in amide proton transfer-weighted (APTw) CEST imaging: New theoretical insights and clinical benefits.

PURPOSE: Amide proton transfer-weighted (APTw) MRI at 3T provides a unique contrast for brain tumor imaging. However, APTw imaging suffers from hyperintensities in liquid compartments such as cystic or necrotic structures and provides a distorted APTw signal intensity. Recently, it has been shown that heuristically motivated fluid suppression can remove such artifacts and significantly improve the readability of APTw imaging. THEORY AND METHODS: In this work, we show that the fluid suppression can actually be understood by the known concept of spillover dilution, which itself can be derived from the Bloch-McConnell equations in comparison to the heuristic approach. Therefore, we derive a novel post-processing formula that efficiently removes fluid artifact, and explains previous approaches. We demonstrate the utility of this APTw assessment in silico, in vitro, and in vivo in brain tumor patients acquired at MR scanners from different vendors. RESULTS: Our results show a reduction of the CEST signals from fluid environments while keeping the APTw-CEST signal intensity almost unchanged for semi-solid tissue structures such as the contralateral normal appearing white matter. This further allows us to use the same color bar settings as for conventional APTw imaging. CONCLUSION: Fluid suppression has considerable value in improving the readability of APTw maps in the neuro-oncological field. In this work, we derive a novel post-processing formula from the underlying Bloch-McConnell equations that efficiently removes fluid artifact, and explains previous approaches which justify the derivation of this metric from a theoretical point of view, to reassure the scientific and medical field about its use.

Performance of Non-EPI DW MRI for Pediatric Cholesteatoma Follow-Up.

OBJECTIVE: To evaluate the accuracy, sensitivity, and specificity of nonecho planar (non-EPI) diffusion-weighted (DW) magnetic resonance imaging (MRI) to detect residual cholesteatoma in children. STUDY DESIGN: Retrospective study. SETTING: Tertiary comprehensive hospital. METHODS: Children operated on for a first-stage cholesteatoma procedure from 2010 to 2019 were included. MRIs were performed with non-EPI DW sequences. Initial reports were collected, indicating the presence or absence of hyperintensity suggestive of cholesteatoma. Three hundred twenty-three MRIs were correlated with the subsequent surgery (66%) or year-later MRI (21%), or were considered accurate if performed 5 years or more after the last surgery (13%). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each imaging procedure for the detection of cholesteatoma were calculated. RESULTS: Two hundred twenty-four children with mean age of 9 ± 4 years old presented with cholesteatoma. MRIs were performed 27 ± 24 months after surgery. Residual cholesteatoma was diagnosed in 35%. The sensitivity, specificity, PPV, and NPV of MRI were 62%, 86%, 74%, and 78%, respectively. Accuracy, sensitivity, and specificity increased significantly over time (multivariate analysis). The mean delay after last surgery was of 30 ± 2.0 months for accurate MRI (true positive or negative) versus 17 ± 2.0 months for nonaccurate (false positive or negative) MRIs (p < .001). CONCLUSION: However, long the delay after the last surgery, the sensitivity of non-EPI diffusion sequence MRI in children has limitations for the detection of residual cholesteatoma. Surveillance for residual cholesteatoma should incorporate findings at primary surgery, surgeon experience, a low threshold for second-look procedures, and routine imaging.

Diffuse midline glioma invasion and metastasis rely on cell-autonomous signaling.

BACKGROUND: Diffuse midline gliomas (DMG) are pediatric tumors with negligible 2-year survival after diagnosis characterized by their ability to infiltrate the central nervous system. In the hope of controlling the local growth and slowing the disease, all patients receive radiotherapy. However, distant progression occurs frequently in DMG patients. Current clues as to what causes tumor infiltration circle mainly around the tumor microenvironment, but there are currently no known determinants to predict the degree of invasiveness. METHODS: In this study, we use patient-derived glioma stem cells (GSCs) to create patient-specific 3D avatars to model interindividual invasion and elucidate the cellular supporting mechanisms. RESULTS: We show that GSC models in 3D mirror the invasive behavior of the parental tumors, thus proving the ability of DMG to infiltrate as an autonomous characteristic of tumor cells. Furthermore, we distinguished 2 modes of migration, mesenchymal and ameboid-like, and associated the ameboid-like modality with GSCs derived from the most invasive tumors. Using transcriptomics of both organoids and primary tumors, we further characterized the invasive ameboid-like tumors as oligodendrocyte progenitor-like, with highly contractile cytoskeleton and reduced adhesion ability driven by crucial over-expression of bone morphogenetic pathway 7 (BMP7). Finally, we deciphered MEK, ERK, and Rho/ROCK kinases activated downstream of the BMP7 stimulation as actionable targets controlling tumor cell motility. CONCLUSIONS: Our findings identify 2 new therapeutic avenues. First, patient-derived GSCs represent a predictive tool for patient stratification in order to adapt irradiation strategies. Second, autocrine and short-range BMP7-related signaling becomes a druggable target to prevent DMG spread and metastasis.

Imaging features to distinguish posterior fossa ependymoma subgroups.

OBJECTIVES: Posterior fossa ependymoma group A (EPN_PFA) and group B (EPN_PFB) can be distinguished by their DNA methylation and give rise to different prognoses. We compared the MRI characteristics of EPN_PFA and EPN_PFB at presentation. METHODS: Preoperative imaging of 68 patients with posterior fossa ependymoma from two centers was reviewed by three independent readers, blinded for histomolecular grouping. Location, tumor extension, tumor volume, hydrocephalus, calcifications, tissue component, enhancement or diffusion signal, and histopathological data (cellular density, calcifications, necrosis, mitoses, vascularization, and microvascular proliferation) were compared between the groups. Categorical data were compared between groups using Fisher's exact tests, and quantitative data using Mann-Whitney tests. We performed a Benjamini-Hochberg correction of the p values to account for multiple tests. RESULTS: Fifty-six patients were categorized as EPN_PFA and 12 as EPN_PFB, with median ages of 2 and 20 years, respectively (p = 0.0008). The median EPN_PFA tumoral volume was larger (57 vs 29 cm3, p = 0.003), with more pronounced hydrocephalus (p = 0.002). EPN_PFA showed an exclusive central position within the 4th ventricle in 61% of patients vs 92% for EPN_PFB (p = 0.01). Intratumor calcifications were found in 93% of EPN_PFA vs 40% of EPN_PFB (p = 0.001). Invasion of the posterior fossa foramina was mostly found for EPN_PFA, particularly the foramina of Luschka (p = 0.0008). EPN_PFA showed whole and homogeneous tumor enhancement in 5% vs 75% of EPN_PFB (p = 0.0008). All mainly cystic tumors were EPN_PFB (p = 0.002). The minimal and maximal relative ADC was slightly lower in EPN_PFA (p = 0.02 and p = 0.01, respectively). CONCLUSION: Morphological characteristics from imaging differ between posterior fossa ependymoma subtypes and may help to distinguish them preoperatively. CLINICAL RELEVANCE STATEMENT: This study provides a tool to differentiate between group A and group B ependymomas, which will ultimately allow the therapeutic strategy to be adapted in the early stages of patient management. KEY POINTS: • Posterior fossa ependymoma subtypes often have different imaging characteristics. • Posterior fossa ependymomas group A are commonly median or lateral tissular calcified masses, with incomplete enhancement, affecting young children and responsible for pronounced hydrocephalus and invasion of the posterior fossa foramina. • Posterior fossa ependymomas group B are commonly median non-calcified masses of adolescents and adults, predominantly cystic, and minimally invasive, with total and homogeneous enhancement.

Identifying interindividual variability of social perception and associated brain anatomical correlations in children with autism spectrum disorder using eye-tracking and diffusion tensor imaging MRI (DTI-MRI).

Even though deficits in social cognition constitute a core characteristic of autism spectrum disorders, a large heterogeneity exists regarding individual social performances and its neural basis remains poorly investigated. Here, we used eye-tracking to objectively measure interindividual variability in social perception and its correlation with white matter microstructure, measured with diffusion tensor imaging MRI, in 25 children with autism spectrum disorder (8.5 ± 3.8 years). Beyond confirming deficits in social perception in participants with autism spectrum disorder compared 24 typically developing controls (10.5 ± 2.9 years), results revealed a large interindividual variability of such behavior among individuals with autism spectrum disorder. Whole-brain analysis showed in both autism spectrum disorder and typically developing groups a positive correlation between number of fixations to the eyes and fractional anisotropy values mainly in right and left superior longitudinal tracts. In children with autism spectrum disorder a correlation was also observed in right and left inferior longitudinal tracts. Importantly, a significant interaction between group and number of fixations to the eyes was observed within the anterior portion of the right inferior longitudinal fasciculus, mainly in the right anterior temporal region. This additional correlation in a supplementary region suggests the existence of a compensatory brain mechanism, which may support enhanced performance in social perception among children with autism spectrum disorder.

Interhemispheric Vertical Hemispherotomy: Technique, Outcome, and Pitfalls-A Bicentric Retrospective Case Series of 39 Cases.

BACKGROUND AND OBJECTIVES: When seizure onset affects a whole hemisphere, hemispheric disconnections are efficient and safe procedures. However, both lateral peri-insular hemispherotomy and vertical paramedian hemispherotomy approaches report a failure rate around 20%, which can be explained by residual connections giving rise to persistent seizures. In this study, we present the interhemispheric vertical hemispherotomy (IVH), a technical variation of the vertical paramedian hemispherotomy approach, that aims to increase seizure control avoiding residual connections while exposing the corpus callosum. METHODS: This is a retrospective study of IVH in two centers, with analysis of clinical and MRI data and outcomes. A detailed description of the technique is provided with a video. RESULTS: IVH was performed in 39 children. The mean age at surgery was 7.2 years, and etiologies were as follows: malformations of cortical development (n = 14), Rasmussen's encephalitis (n = 10), stroke (n = 10), post-traumatic (3), and Sturge-Weber Syndrome (2). Hemispheric disconnection was complete on postoperative MRI in 34 cases. There was no mortality, hydrocephalus occurred in one case, and subdural collection occurred in four cases. A second surgery was performed in four cases because of seizure relapse (n = 3) and/or incomplete disconnection on MRI (n = 4). With a mean follow-up of 3.2 years, International League Against Epilepsy class I epilepsy outcome was obtained for 37/39 patients. CONCLUSION: IVH is a safe and effective variation of the vertical approaches for hemispheric disconnection. It allows a good exposure and anatomic control of the corpus callosum, which is a frequent site of incomplete disconnection. IVH may be limited by the thalamic volume and the ventricular size, notably in hemimegalencephaly cases.

Evidence of spinal stiffening following fusionless bipolar fixation for neuromuscular scoliosis: a shear wave elastography assessment of lumbar annulus fibrosus.

OBJECTIVES: There are no established criteria for stiffness after fusionless surgery for neuromuscular scoliosis (NMS). As a result, there is no consensus regarding the surgical strategy to propose at long-term follow-up. This study reports the first use of shear wave elastography for assessing the mechanical response of lumbar intervertebral discs (IVDs) after fusionless bipolar fixation (FBF) for NMS and compares them with healthy controls. The aim was to acquire evidence from the stiffness of the spine following FBF. PATIENTS AND METHODS: Nineteen NMS operated on with FBF (18 ± 2y at last follow-up, 6 ± 1 y after surgery) were included prospectively. Preoperative Cobb was 89 ± 20° and 35 ± 1° at latest follow-up. All patients had reached skeletal maturity. Eighteen healthy patients (20 ± 4 y) were also included. Shear wave speed (SWS) was measured in the annulus fibrosus of L3L4, L4L5 and L5S1 IVDs and compared between the two groups. A measurement reliability was performed. RESULTS: In healthy subjects, average SWS (all disc levels pooled) was 7.5 ± 2.6 m/s. In NMS patients, SWS was significantly higher at 9.9 ± 1.4 m/s (p < 0.05). Differences were significant between L3L4 (9.3 ± 1.8 m/s vs. 7.0 ± 2.5 m/s, p = 0.004) and L4L5 (10.3 ± 2.3 m/s vs. 7.1 ± 1.1 m/s, p = 0.0006). No difference was observed for L5S1 (p = 0.2). No correlation was found with age at surgery, Cobb angle correction and age at the SWE measurement. CONCLUSIONS: This study shows a significant increase in disc stiffness at the end of growth for NMS patients treated by FBF. These findings are a useful adjunct to CT-scan in assessing stiffness of the spine allowing the avoidance of surgical final fusion at skeletal maturity.