Alterations in Functional and Structural Connectivity in Pediatric-Onset Multiple Sclerosis

Pediatric Neuroimaging of Multiple Sclerosis and Neuroinflammatory Diseases

Using a pediatric-focused lens, this review article briefly summarizes the presentation of several demyelinating and neuroinflammatory diseases using conventional magnetic resonance imaging (MRI) sequences, such as T1-weighted with and without an exogenous gadolinium-based contrast agent, T2-weighted, and fluid-attenuated inversion recovery (FLAIR). These conventional sequences exploit the intrinsic properties of tissue to provide a distinct signal contrast that is useful for evaluating disease features and monitoring treatment responses in patients by characterizing lesion involvement in the central nervous system and tracking temporal features with blood-brain barrier disruption. Illustrative examples are presented for pediatric-onset multiple sclerosis and neuroinflammatory diseases. This work also highlights findings from advanced MRI techniques, often infrequently employed due to the challenges involved in acquisition, post-processing, and interpretation, and identifies the need for future studies to extract the unique information, such as alterations in neurochemistry, disruptions of structural organization, or atypical functional connectivity, that may be relevant for the diagnosis and management of disease.

Compensatory mechanisms amidst demyelinating disorders: insights into cognitive preservation

Demyelination disrupts the transmission of electrical signals in the brain and affects neurodevelopment in children with disorders such as multiple sclerosis and myelin oligodendrocyte glycoprotein-associated disorders. Although cognitive impairments are prevalent in these conditions, some children maintain cognitive function despite substantial structural injury. These findings raise an important question: in addition to the degenerative process, do compensatory neural mechanisms exist to mitigate the effects of myelin loss? We propose that a multi-dimensional approach integrating multiple neuroimaging modalities, including diffusion tensor imaging, magnetoencephalography and eye-tracking, is key to investigating this question. We examine the structural and functional connectivity of the default mode and executive control networks due to their significant roles in supporting higher-order cognitive processes. As cognitive proxies, we examine saccade reaction times and direction errors during an interleaved pro- (eye movement towards a target) and anti-saccade (eye movement away from a target) task. 28 typically developing children, 18 children with multiple sclerosis and 14 children with myelin oligodendrocyte glycoprotein-associated disorders between 5 and 18.9 years old were scanned at the Hospital for Sick Children. Tractography of diffusion MRI data examined structural connectivity. Intracellular and extracellular microstructural parameters were extracted using a white matter tract integrity model to provide specific inferences on myelin and axon structure. Magnetoencephalography scanning was conducted to examine functional connectivity. Within groups, participants had longer saccade reaction times and greater direction errors on the anti- versus pro-saccade task; there were no group differences on either task. Despite similar behavioural performance, children with demyelinating disorders had significant structural compromise and lower bilateral high gamma, higher left-hemisphere theta and higher right-hemisphere alpha synchrony relative to typically developing children. Children diagnosed with multiple sclerosis had greater structural compromise relative to children with myelin oligodendrocyte glycoprotein-associated disorders; there were no group differences in neural synchrony. For both patient groups, increased disease disability predicted greater structural compromise, which predicted longer saccade reaction times and greater direction errors on both tasks. Structural compromise also predicted increased functional connectivity, highlighting potential adaptive functional reorganisation in response to structural compromise. In turn, increased functional connectivity predicted faster saccade reaction times and fewer direction errors. These findings suggest that increased functional connectivity, indicated by increased alpha and theta synchrony, may be necessary to compensate for structural compromise and preserve cognitive abilities. Further understanding these compensatory neural mechanisms could pave the way for the development of targeted therapeutic interventions aimed at enhancing these mechanisms, ultimately improving cognitive outcomes for affected individuals.

Lesion phenotyping based on magnetic susceptibility in pediatric multiple sclerosis

BACKGROUND AND PURPOSE

Pediatric multiple sclerosis (MS) displays different pathological features compared to adult MS, which can be studied in vivo by assessing tissue magnetic susceptibility with 3T-MRI. We aimed to assess different white matter lesions (WMLs) phenotypes in pediatric MS patients using quantitative susceptibility mapping (QSM) and susceptibility mapping weighted imaging (SMWI) over 12 months.

METHODS

Eleven pediatric MS patients [female: 63.6%; mean ± standard deviation (SD) age and disease duration: 16.3 ± 2.2 and 2.4 ± 1.5; median (range) Expanded Disability Status Scale (EDSS) 1 (0-2)] underwent 3 Tesla-MRI exams and EDSS assessments at baseline and after 1 year. QSM and SMWI were obtained using 3-dimensional (3D)-segmented echo-planar-imaging with submillimetric spatial resolution. WMLs were classified according to their QSM appearance and SMWI was used to identify QSM hyperintensities ascribable to veins. Total brain volumes at baseline and follow-up were computed using high-resolution 3D T1-weighted images.

RESULTS

Mean ± SD paramagnetic rim lesions (PRLs) prevalence was 7.0% ± 9.0. Fifty-four percent (6/11) of patients exhibited at least one PRL, with one patient exhibiting ≥ 4 PRLs. All patients showed QSM-iso-/hypo-intense lesions, which represented a mean ± SD of 65.8% ± 22.7 of total WMLs. QSM-hyperintense WMLs showed a positive correlation with total brain volume reduction at follow-up (r = 0.705; p =  .02). No lesion was classified as different between baseline and follow-up.

CONCLUSION

Chronic compartmentalized inflammation seems to occur early in pediatric MS patients with short disease duration. A high prevalence of iso-/hypo-intense lesions was found, which could account for the higher remyelination potential in pediatric MS.

Bibliometric analysis of myelin imaging studies of patients with multiple sclerosis (2000-2022)

Background

Multiple sclerosis (MS) is a condition that can impact the central nervous system (CNS) and cause damage to the myelin, which is responsible for facilitating the normal transmission of electrical impulses along the nerves. We performed a bibliometric analysis of the scientific publications on myelin imaging in MS to reveal the development trends in this field and to evaluate research trends in myelin imaging in MS.

Methods

The Web of Science Core Collection was searched for articles related to myelin imaging in MS published between January 2000 and December 2022. CiteSpace, VOSviewer, and R language were used to evaluate and visualize contributions by and co-occurrence relationships among countries and institutions, authors, journals, citations, keywords, and so on.

Results

A total of 1,639 articles addressed the topic of myelin imaging in MS. The United States had the largest number of annual publications. The University of London was the institution with the highest number of publications (n=118) and citations (n=9,885). The top 3 productive authors were all from the University of British Columbia in Canada. An article published by Mackay et al. in 1994 had the most citations (n=272). Neuroimage [impact factor (IF) =7.40, Journal Citation Reports quartile 1 (Q1)] was the most productive journal in terms of the number of articles relating to myelin imaging in MS (n=149). In recent years, myelin water imaging, synthetic magnetic resonance imaging (SyMRI), inhomogeneous magnetization, positron emission tomography (PET) imaging, and aquaporin-4 (AQP4) have been researched hotspots of myelin imaging in MS.

Conclusions

With advancements in the pathophysiological research on myelin changes in MS, myelin imaging is playing an important role in the diagnosis and treatment of MS. In addition, the use of new sequences of myelin imaging to distinguish MS from other inflammatory demyelinating diseases is a future development trend in this field.

The Economic and Humanistic Burden of Pediatric-Onset Multiple Sclerosis

Background: Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system. Pediatric-onset MS (POMS), defined as onset of MS before 18 years of age, is estimated to account for 2% to 5% of the MS population worldwide. Objectives: To conduct a literature review focused on the healthcare resource utilization and cost as well as quality-of-life (QOL) outcomes among patients with POMS. Methods: We conducted a systematic literature review of English-language studies published after September 2010 in MEDLINE and Embase to describe the global economic healthcare resource utilization and costs and humanistic (QOL) burden in patients with POMS. Results: We found 11 studies that reported on healthcare resource utilization, cost, or insurance coverage and 36 studies that reported on QOL outcomes in patients with POMS. Patients with POMS had higher rates of primary care visits (1.41 [1.29-1.54]), hospital visits (10.74 [8.95-12.90]), and admissions (rate ratio, 4.27 [2.92-6.25];OR, 15.2 [12.0-19.1]) compared with healthy controls. Mean per-patient costs in the United States were $5907 across all settings per year of follow-up between 2002 and 2012; mean costs per hospital stay were $38 543 (in 2015 USD) between 2004 and 2013. Three studies reported psychosocial scores between 71.59 and 79.7, and 8 studies reported physical health scores between 74.62 to 82.75 using the Pediatric Quality of Life Measurement Model (PedsQLTM). Twelve studies used the PedsQL™ Multidimensional Fatigue Scale. Mean scores on the self-reported general fatigue scale ranged from 63.15 to 78.5. Quality-of-life scores were lower than those of healthy controls. Discussion: Our review presents a uniquely broad and recent overview of the global economic and humanistic burden of patients with POMS. Additional research on healthcare resource utilization and cost would provide a more robust understanding of the economic burden in this population. Conclusions: Healthcare resource utilization and costs are high in this population, and patients report reduced QOL and significant fatigue compared with healthy children and adolescents.

Patterns of white and gray structural abnormality associated with paediatric demyelinating disorders

•

A multi-modal approach was used to evaluate the visual pathway from anterior (retina) to posterior (visual cortex) in both paediatric MOGAD and MS patients.

•

MS patients exhibited more widespread white matter abnormalities; MOGAD patients exhibited white matter changes primarily within the optic radiation.

•

The pattern of cortical thinning differed in MS and MOGAD patients.

•

Reduced RNFLT was associated with lower axonal density in MOGAD and tortuosity in MS.

The impact of multiple sclerosis (MS) and myelin oligodendrocyte glycoprotein (MOG) - associated disorders (MOGAD) on brain structure in youth remains poorly understood. Reductions in cortical mantle thickness on structural MRI and abnormal diffusion-based white matter metrics (e.g., diffusion tensor parameters) have been well documented in MS but not in MOGAD. Characterizing structural abnormalities found in children with these disorders can help clarify the differences and similarities in their impact on neuroanatomy. Importantly, while MS and MOGAD affect the entire CNS, the visual pathway is of particular interest in both groups, as most patients have evidence for clinical or subclinical involvement of the anterior visual pathway. Thus, the visual pathway is of key interest in analyses of structural abnormalities in these disorders and may distinguish MOGAD from MS patients.

In this study we collected MRI data on 18 MS patients, 14 MOGAD patients and 26 age- and sex-matched typically developing children (TDC). Full-brain group differences in fixel diffusion measures (fibre-bundle populations) and cortical thickness measures were tested using age and sex as covariates. Visual pathway analysis was performed by extracting mean diffusion measures within lesion free optic radiations, cortical thickness within the visual cortex, and retinal nerve fibre layer (RNFL) and ganglion cell layer thickness measures from optical coherence tomography (OCT). Fixel based analysis (FBA) revealed MS patients have widespread abnormal white matter within the corticospinal tract, inferior longitudinal fasciculus, and optic radiations, while within MOGAD patients, non-lesional impact on white matter was found primarily in the right optic radiation. Cortical thickness measures were reduced predominately in the temporal and parietal lobes in MS patients and in frontal, cingulate and visual cortices in MOGAD patients. Additionally, our findings of associations between reduced RNFLT and axonal density in MOGAD and TORT in MS patients in the optic radiations imply widespread axonal and myelin damage in the visual pathway, respectively. Overall, our approach of combining FBA, cortical thickness and OCT measures has helped evaluate similarities and differences in brain structure in MS and MOGAD patients in comparison to TDC.

Pediatric multiple sclerosis: developments in timely diagnosis and prognostication

INTRODUCTION

Pediatric-onset (PO) multiple sclerosis (MS) accounts for about 2-10% of the total MS cases. Recently, a greater attention has been given to POMS, with substantial improvements in the understanding of its pathophysiology, in the diagnostic work-up and in the identification of reliable prognosticators associated with long-term disability in these patients.

AREAS COVERED

This review summarizes the most recent updates regarding the pathophysiology of POMS, the current diagnostic criteria and the clinical, neuroradiological and laboratoristic markers that have been associated with disease progression (i.e. occurrence of a second clinical attack at disease onset and accumulation of disability in definite MS).

EXPERT OPINION

The study of POMS, where the clinical onset is closer to the biological onset of MS, may contribute to better understand how the different pathological processes impact brain maturation and contribute to disease progression, but also how brain plasticity may counterbalance structural damage accumulation. Although rare, POMS is a severe disease, characterized by a prominent clinical and radiological activity at disease onset and by the accumulation of physical and cognitive disability at a younger age compared to the adult counterpart, with significant detrimental consequences at long-term. Early and accurate diagnosis, together with early treatment, is highly warranted.

Disrupted cognitive development following pediatric acquired demyelinating syndromes: a longitudinal study

Long-term cognitive deficits have been observed in some children who experience an acquired demyelinating syndrome (ADS). We examined changes in cognitive functioning over the first two years following incident ADS andtested whether normalized brain and thalamic volume accounted for decline over time. Twenty-five youth (mean age 12.8 years) with ADS, 9 of whom were diagnosed with multiple sclerosis (MS) and 16 of whom experienced monophasic ADS (monoADS), underwent two neuropsychological evaluationsand MRI scans at approximately6- and 24-months post ADS-onset. We examined changes in cognitive outcomes over time and between patient groups. Generalized linear mixed-effect regression models were used to examine the association of normalized brain and thalamic volumesbetween the two timepointswith cognitive z-scores. Cognitive performance was within the age-expected range for both groups and remained stable over time on 15 measures. In the combined sample of monoADS and MS patients, declines (p < .05) were noted on the Symbol Digit Modalities Test (SDMT), the Auditory Working Memory (AWM), and the WJ-III Visual Matching (VisMat)tests, but did not survive FDR correction. Clinically significant declines, as measured by the Reliable Change Index, were observed on the SDMT,AWM, and VisMattests by 19, 42, and 32%, respectively. Lower normalized brain volume at 6-months predicted a negative change in SDMT (B = 0.45, 95%CI: 0.07,0.83) and AWM (B = 0.30, 95%CI: 0.13, 0.47). Chronicity of demyelination is not required for cognitive decline nor for reduced brain volume, suggesting that even a single demyelinating event may negatively impact cognitive potential in children.

Pediatric inflammatory demyelinating disorders and mimickers: How to differentiate with MRI?

Multiple sclerosis (MS) is a chronic, immune-mediated, neurodegenerative disorder of the central nervous system (CNS).While the clinical symptoms of MS most commonly manifest between 20 and 40 years of age, approximately 3 to 10% of all MS patients report that their first inaugural events can occur earlier in life, even in childhood, and thus include the pediatric population. The prevalence of MS onset in childhood/adolescence varies between 2.0% and 4.0% of all MS cases according to several extensive studies. The main imaging patterns of pediatric inflammatory demyelinating disorders and mimicking entities, including multiple sclerosis, neuromyelitis optica spectrum disorders, acute disseminated encephalomyelitis, MOG (myelin oligodendrocyte glycoprotein) antibody-related disorders and differential diagnoses will be addressed in this article, highlighting key points to the differential diagnosis.

Paediatric multiple sclerosis and antibody-associated demyelination: clinical, imaging, and biological considerations for diagnosis and care

The field of acquired CNS neuroimmune demyelination in children is transforming. Progress in assay development, refinement of diagnostic criteria, increased biological insights provided by advanced neuroimaging techniques, and high-level evidence for the therapeutic efficacy of biological agents are redefining diagnosis and care. Three distinct neuroimmune conditions-multiple sclerosis, myelin-oligodendrocyte glycoprotein antibody-associated disease (MOGAD), and aquaporin-4 antibody-associated neuromyelitis optica spectrum disorder (AQP4-NMOSD)-can now be distinguished, with evidence from humans and animal models supporting distinct pathobiological disease mechanisms. The development of highly effective therapies for adult-onset multiple sclerosis and AQP4-NMOSD that suppress relapse rate by more than 90% has motivated advocacy for trials in children. However, doing clinical trials is challenging because of the rarity of these conditions in the paediatric age group, necessitating new approaches to trial design, including age-based trajectory modelling based on phase 3 studies in adults. Despite these limitations, the future for children and adolescents living with multiple sclerosis, MOGAD, or AQP4-NMOSD is far brighter than in years past, and will be brighter still if successful therapies to promote remyelination, enhance neuroprotection, and remediate cognitive deficits can be further accelerated.

Impairments of white matter tracts and connectivity alterations in five cognitive networks of patients with multiple sclerosis

INTRODUCTION

MS is associated with structural and functional brain alterations leading to cognitive impairments across multiple domains including attention, memory, and speed of information processing. Here, we analyzed the white matter damage and topological organization of white matter tracts in specific brain regions responsible for cognition in MS.

METHODS

Brain DTI, rs-fMRI, T1, T2, and T2-FLAIR were acquired for 22 MS subjects and 22 healthy controls. Automatic brain parcellation was performed on T1-weighted images. Skull-stripped T1-weighted intensity inverted images were co-registered to the b0 image. Diffusion-weighted images were processed to perform whole brain tractography. The rs-fMRI data were processed, and the connectivity matrixes were analyzed to identify significant differences in the network of nodes between the two groups using NBS analysis. In addition, diffusion entropy maps were produced from DTI data sets using in-house software.

RESULTS

MS subjects exhibited significantly reduced mean FA and entropy in 38 and 34 regions, respectively, out of a total of 54 regions. The connectivity values in both structural and functional analyses were decreased in most regions of the default mode network and in four other cognitive networks in MS subjects compared to healthy controls. MS also induced significant reduction in the normalized hippocampus and corpus callosum volumes; the normalized hippocampus volume was significantly correlated with EDSS scores.

CONCLUSION

MS subjects have significant white matter damage and reduction of FA and entropy in various brain regions involved in cognitive networks. Structural and functional connectivity within the default mode network and an additional four cognitive networks exhibited significant changes compared with healthy controls.

Reduced fractional anisotropy in projection, association, and commissural fiber networks in neonates with prenatal methamphetamine exposure

Prenatal exposure to methamphetamine is associated with neurostructural changes, including alterations in white matter microstructure. This study investigated the effects of methamphetamine exposure on microstructure of global white matter networks in neonates. Pregnant women were interviewed beginning in mid-pregnancy regarding their methamphetamine use. Diffusion weighted imaging sets were acquired for 23 non-sedated neonates. White matter bundles associated with pairs of target regions within five networks (commissural fibers, left and right projection fibers, and left and right association fibers) were estimated using probabilistic tractography, and fractional anisotropy (FA) and diffusion measures determined within each connection. Multiple regression analyses showed that increasing methamphetamine exposure was significantly associated with reduced FA in all five networks, after control for potential confounders. Increased exposure was associated with lower axial diffusivity in the right association fiber network and with increased radial diffusivity in the right projection and left and right association fiber networks. Within the projection and association networks a subset of individual connections showed a negative correlation between FA and methamphetamine exposure. These findings are consistent with previous reports in older children and demonstrate that microstructural changes associated with methamphetamine exposure are already detectable in neonates.

MRI features associated with high likelihood of conversion of radiologically isolated syndrome to multiple sclerosis

Radiologically isolated syndrome (RIS) is the asymptomatic precursor to clinically isolated syndrome, relapsing-remitting multiple sclerosis (MS) or primary progressive MS. RIS is frequently diagnosed when an individual gets an MRI for an unrelated medical issue, such as headache or trauma. Treating RIS patients is controversial, but physicians may be inclined to offer prophylactic treatment for high-risk RIS patients. Identifying imaging and clinical features associated with high likelihood of early clinical conversion may prove helpful to identify a high-risk subset for potential MS therapy. The goal of this paper is to review current literatures to identify imaging and clinical features that predict early (within 5 years) conversion from RIS to MS.

Advances in brain imaging in multiple sclerosis

Brain imaging is increasingly used to support clinicians in diagnosing multiple sclerosis (MS) and monitoring its progression. However, the role of magnetic resonance imaging (MRI) in MS goes far beyond its clinical application. Indeed, advanced imaging techniques have helped to detect different components of MS pathogenesis in vivo, which is now considered a heterogeneous process characterized by widespread damage of the central nervous system, rather than multifocal demyelination of white matter. Recently, MRI biomarkers more sensitive to disease activity than clinical disability outcome measures, have been used to monitor response to anti-inflammatory agents in patients with relapsing-remitting MS. Similarly, MRI markers of neurodegeneration exhibit the potential as primary and secondary outcomes in clinical trials for progressive phenotypes. This review will summarize recent advances in brain neuroimaging in MS from the research setting to clinical applications.

White matter plasticity and maturation in human cognition

White matter plasticity likely plays a critical role in supporting cognitive development. However, few studies have used the imaging methods specific to white matter tissue structure or experimental designs sensitive to change in white matter necessary to elucidate these relations. Here we briefly review novel imaging approaches that provide more specific information regarding white matter microstructure. Furthermore, we highlight recent studies that provide greater clarity regarding the relations between changes in white matter and cognition maturation in both healthy children and adolescents and those with white matter insult. Finally, we examine the hypothesis that white matter is linked to cognitive function via its impact on neural synchronization. We test this hypothesis in a population of children and adolescents with recurrent demyelinating syndromes. Specifically, we evaluate group differences in white matter microstructure within the optic radiation; and neural phase synchrony in visual cortex during a visual task between 25 patients and 28 typically developing age-matched controls. Children and adolescents with demyelinating syndromes show evidence of myelin and axonal compromise and this compromise predicts reduced phase synchrony during a visual task compared to typically developing controls. We investigate one plausible mechanism at play in this relationship using a computational model of gamma generation in early visual cortical areas. Overall, our findings show a fundamental connection between white matter microstructure and neural synchronization that may be critical for cognitive processing. In the future, longitudinal or interventional studies can build upon our knowledge of these exciting relations between white matter, neural communication, and cognition.

Long-term Chinese calligraphic handwriting training has a positive effect on brain network efficiency

As a visual art form, Chinese calligraphic handwriting (CCH) has been found to correlate with certain brain activity and to induce functional connectivity reorganization of the brain. This study investigated the effect of long-term CCH training on brain functional plasticity as assessed with network measures. With the resting-state fMRI data from 31 participants with at least five years of CCH training and 40 controls, we constructed brain functional networks, examined group differences at both the whole brain and modular levels, and correlated the topological characteristics with calligraphy skills. We found that, compared to the control group, the CCH group showed shorter characteristic path lengths and higher local efficiency in certain brain areas in the frontal and parietal cortices, limbic system, basal ganglia, and thalamus. Moreover, these network measures in the cingulate cortex, caudate nucleus, and thalamus were associated with CCH performance (i.e., copying and creating skills). These results suggest that long-term CCH training has a positive effect on the topological characteristics of brain networks.

Functional Connectivity in Multiple Sclerosis: Recent Findings and Future Directions

Multiple sclerosis is a debilitating disorder resulting from scattered lesions in the central nervous system. Because of the high variability of the lesion patterns between patients, it is difficult to relate existing biomarkers to symptoms and their progression. The scattered nature of lesions in multiple sclerosis offers itself to be studied through the lens of network analyses. Recent research into multiple sclerosis has taken such a network approach by making use of functional connectivity. In this review, we briefly introduce measures of functional connectivity and how to compute them. We then identify several common observations resulting from this approach: (a) high likelihood of altered connectivity in deep-gray matter regions, (b) decrease of brain modularity, (c) hemispheric asymmetries in connectivity alterations, and (d) correspondence of behavioral symptoms with task-related and task-unrelated networks. We propose incorporating such connectivity analyses into longitudinal studies in order to improve our understanding of the underlying mechanisms affected by multiple sclerosis, which can consequently offer a promising route to individualizing imaging-related biomarkers for multiple sclerosis.

Pediatric Multiple Sclerosis: Distinguishing Clinical and MR Imaging Features

This article presents an overview of evolving diagnostic criteria of pediatric multiple sclerosis and related disorders, emphasizing distinguishing clinical and neuroimaging features that should be considered for differential diagnosis in childhood and adolescence. New data on the integrity of brain tissue in children with MS provided by advanced MR imaging techniques are addressed as well.

Paediatric multiple sclerosis and other acute demyelinating diseases

PURPOSE OF REVIEW

Neuroimmunological diseases encompass a wide spectrum of diseases in children. Apart from the discovery of autoantibodies affecting primarily grey matter structures and the improved clinical characterization of rare entities such as N-methyl D-aspartate receptor-R- encephalitis, important strides have also been made in autoimmune-mediated white matter diseases, including paediatric multiple sclerosis (pedMS) and other acute demyelinating syndromes (ADS) often associated with antibodies (abs) against myelin-oligodendrocyte-glycoprotein (MOG). This review will cover findings of recent studies in pedMS, in the emerging field of non-MS acute demyelinating episodes associated with MOG abs and lastly from new imaging techniques such as diffusion tensor imaging (DTI) revealing new insights in the pathogenesis of ADS in children.

RECENT FINDINGS

The first prospective randomized clinical pedMS trial assessing the clinical and radiological efficacy of fingolimod versus a standard disease-modifying agent has shown clear superiority of fingolimod. The clinical spectrum of MOG-associated diseases has been characterized in more detail revealing clinical subtypes distinct from pedMS. A recent large European study further showed that MOG-associated diseases do not respond to first-line disease-modifying treatment (DMT) in MS but fare better with B-cell modulating therapies including regular intravenous immunoglobulin (IVIG).

SUMMARY

Recent findings strongly indicate that in particular in highly active pedMS characterized by new relapses or accrual of new MRI lesions despite first-line DMT treatment should be escalated. Secondly, several studies have shown that MOG-spectrum diseases include children with monophasic and recurrent subtypes other than MS with different clinical, radiological characteristics and treatment challenges.

Pronounced Structural and Functional Damage in Early Adult Pediatric-Onset Multiple Sclerosis with No or Minimal Clinical Disability

Pediatric-onset multiple sclerosis (POMS) may represent a model of vulnerability to damage occurring during a period of active maturation of the human brain. Whereas adaptive mechanisms seem to take place in the POMS brain in the short-medium term, natural history studies have shown that these patients reach irreversible disability, despite slower progression, at a significantly younger age than adult-onset MS (AOMS) patients. We tested for the first time whether significant brain alterations already occurred in POMS patients in their early adulthood and with no or minimal disability (n = 15) in comparison with age- and disability-matched AOMS patients (n = 14) and to normal controls (NC, n = 20). We used a multimodal MRI approach by modeling, using FSL, voxelwise measures of microstructural integrity of white matter tracts and gray matter volumes with those of intra- and internetwork functional connectivity (FC) (analysis of variance, p ≤ 0.01, corrected for multiple comparisons across space). POMS patients showed, when compared with both NC and AOMS patients, altered measures of diffusion tensor imaging (reduced fractional anisotropy and/or increased diffusivities) and higher probability of lesion occurrence in a clinically eloquent region for physical disability such as the posterior corona radiata. In addition, POMS patients showed, compared with the other two groups, reduced long-range FC, assessed from resting functional MRI, between default mode network and secondary visual network, whose interaction subserves important cognitive functions such as spatial attention and visual learning. Overall, this pattern of structural damage and brain connectivity disruption in early adult POMS patients with no or minimal clinical disability might explain their unfavorable clinical outcome in the long term.

White matter changes in paediatric multiple sclerosis and monophasic demyelinating disorders

See Hacohen et al. (doi:10.1093/awx075) for a scientific commentary on this article. Most children who experience an acquired demyelinating syndrome of the central nervous system will have a monophasic disease course, with no further clinical or radiological symptoms. A subset will be diagnosed with multiple sclerosis, a life-long disorder. Using linear mixed effects models we examined longitudinal diffusion properties of normal-appearing white matter in 505 serial scans of 132 paediatric participants with acquired demyelinating syndromes followed for a median of 4.4 years, many from first clinical presentation, and 106 scans of 80 healthy paediatric participants. Fifty-three participants with demyelinating syndromes eventually received a diagnosis of paediatric-onset multiple sclerosis. Diffusion tensor imaging measures properties of water diffusion through tissue, which normally becomes increasingly restricted and anisotropic in the brain during childhood and adolescence, as fibre bundles develop and myelinate. In the healthy paediatric participants, our data demonstrate the expected trajectory of more restricted and anisotropic white matter diffusivity with increasing age. However, in participants with multiple sclerosis, fractional anisotropy decreased and mean diffusivity of non-lesional, normal-appearing white matter progressively increased after clinical presentation, suggesting not only a failure of age-expected white matter development but also a progressive loss of tissue integrity. Surprisingly, patients with monophasic disease failed to show age-expected changes in diffusion parameters in normal-appearing white matter, although they did not show progressive loss of integrity over time. Further analysis demonstrated that participants with monophasic disease experienced different post-onset trajectories in normal-appearing white matter depending on their presenting phenotype: those with acute disseminated encephalomyelitis demonstrated abnormal trajectories of diffusion parameters compared to healthy paediatric participants, as did patients with non-acute disseminated encephalomyelitis presentations associated with lesions in the brain at onset. Patients with monofocal syndromes such as optic neuritis, transverse myelitis, or isolated brainstem syndromes in whom multifocal brain lesions were absent, showed trajectories more closely approximating normal-appearing white matter development. Our findings also suggest the existence of sexual dimorphism in the effects of demyelinating syndromes on normal-appearing white matter development. Overall, we demonstrate failure of white matter maturational changes and progressive loss of white matter integrity in paediatric-onset multiple sclerosis, but also show that even a single demyelinating attack-when associated with white matter lesions in the brain-negatively impacts subsequent normal-appearing white matter development.

MRI substrates of sustained attention system and cognitive impairment in pediatric MS patients

Objective:

To explore the structural and functional integrity of the sustained attention system in patients with pediatric multiple sclerosis (MS) and its effect on cognitive impairment.

Methods:

We enrolled 57 patients with pediatric MS and 14 age- and sex-matched healthy controls (HCs). Patients with >3 abnormal tests at neuropsychological evaluation were classified as cognitively impaired (CI). Sustained attention system activity was studied with fMRI during the Conners Continuous Performance Test (CCPT). Structural integrity of attention network connections was quantified with diffusion tensor (DT) MRI.

Results:

Within-group analysis showed similar patterns of recruitment of the attention network in HCs and patients with pediatric MS. Diffuse network DT MRI structural abnormalities were found in patients with MS. During CCPT, with increasing task demand, patients with pediatric MS showed increased activation of the left thalamus, anterior insula, and anterior cingulate cortex (ACC) and decreased recruitment of the right precuneus compared to HCs. Thirteen patients (23%) were classified as CI. Compared to cognitively preserved patients, CI patients with pediatric MS had decreased recruitment of several areas located mainly in parietal and occipital lobes and cerebellum and increased deactivation of the ACC, combined with more severe structural damage of white matter tracts connecting these regions.

Conclusions:

Our results suggest that the age-expected level of sustained attention system functional competence is achieved in patients with pediatric MS. Inefficient regulation of the functional interaction between different areas of this system, due to abnormal white matter integrity, may result in global cognitive impairment in these patients.