Intracortical lesions by 3T magnetic resonance imaging and correlation with cognitive impairment in multiple sclerosis

The contribution of paramagnetic rim and cortical lesions to physical and cognitive disability at multiple sclerosis clinical onset: evaluating the power of MRI and OCT biomarkers

BACKGROUND

In multiple sclerosis (MS), imaging biomarkers play a crucial role in characterizing the disease at the time of diagnosis. MRI and optical coherence tomography (OCT) provide readily available biomarkers that may help to define the patient's clinical profile. However, the evaluation of cortical and paramagnetic rim lesions (CL, PRL), as well as retinal atrophy, is not routinely performed in clinic.

OBJECTIVE

To identify the most significant MRI and OCT biomarkers associated with early clinical disability in MS.

METHODS

Brain, spinal cord (SC) MRI, and OCT scans were acquired from 45 patients at MS diagnosis to obtain: brain PRL and non-PRL, CL, SC lesion volumes and counts, brain volumetric metrics, SC C2-C3 cross-sectional area, and retinal layer thickness. Regression models assessed relationships with physical disability (Expanded Disability Status Scale [EDSS]) and cognitive performance (Brief International Cognitive Assessment for Multiple Sclerosis [BICAMS]).

RESULTS

In a stepwise regression (R2 = 0.526), PRL (β = 0.001, p = 0.023) and SC lesion volumes (β = 0.001, p = 0.017) were the most significant predictors of EDSS, while CL volume and age were strongly associated with BICAMS scores. Moreover, in a model where PRL and non-PRL were pooled, only the contribution of SC lesion volume was retained in EDSS prediction. OCT measures did not show associations with disability at the onset.

CONCLUSION

At MS onset, PRL and SC lesions exhibit the strongest association with physical disability, while CL strongly contribute to cognitive performance. Incorporating the evaluation of PRL and CL into the initial MS patient assessment could help define their clinical profile, thus supporting the treatment choice.

Subtypes and location of (juxta)cortical lesions relate to cognitive dysfunction in people with multiple sclerosis

BACKGROUND

Cortical lesion subtypes' occurrence and distribution across networks may shed light on cognitive impairment (CI) in multiple sclerosis (MS).

METHODS

In 332 people with MS, lesions were classified as intracortical, leukocortical or juxtacortical based on artificially generated double inversion-recovery images.

RESULTS

CI-related leukocortical lesion count increases were greatest within sensorimotor and cognitive networks (p < 0.001). Only intracortical lesion count could distinguish between cognitive groups (p = 0.024). Effect sizes were two- to four-fold larger than differences between MS phenotypes.

CONCLUSION

In CI-MS, leukocortical lesions predominate, whereas intracortical lesions distinguish cognitive groups. Lesions' grey matter (GM) involvement might be decisive for cognition in MS, surpassing overall disease burden.

Contribution of new and chronic cortical lesions to disability accrual in multiple sclerosis

Cortical lesions are common in multiple sclerosis and are associated with disability and progressive disease. We asked whether cortical lesions continue to form in people with stable white matter lesions and whether the association of cortical lesions with worsening disability relates to pre-existing or new cortical lesions. Fifty adults with multiple sclerosis and no new white matter lesions in the year prior to enrolment (33 relapsing-remitting and 17 progressive) and a comparison group of nine adults who had formed at least one new white matter lesion in the year prior to enrolment (active relapsing-remitting) were evaluated annually with 7 tesla (T) brain MRI and 3T brain and spine MRI for 2 years, with clinical assessments for 3 years. Cortical lesions and paramagnetic rim lesions were identified on 7T images. Seven total cortical lesions formed in 3/30 individuals in the stable relapsing-remitting group (median 0, range 0-5), four total cortical lesions formed in 4/17 individuals in the progressive group (median 0, range 0-1), and 16 cortical lesions formed in 5/9 individuals in the active relapsing-remitting group (median 1, range 0-10, stable relapsing-remitting versus progressive versus active relapsing-remitting P = 0.006). New cortical lesions were not associated with greater change in any individual disability measure or in a composite measure of disability worsening (worsening Expanded Disability Status Scale or 9-hole peg test or 25-foot timed walk). Individuals with at least three paramagnetic rim lesions had a greater increase in cortical lesion volume over time (median 16 µl, range -61 to 215 versus median 1 µl, range -24 to 184, P = 0.007), but change in lesion volume was not associated with disability change. Baseline cortical lesion volume was higher in people with worsening disability (median 1010 µl, range 13-9888 versus median 267 µl, range 0-3539, P = 0.001, adjusted for age and sex) and in individuals with relapsing-remitting multiple sclerosis who subsequently transitioned to secondary progressive multiple sclerosis (median 2183 µl, range 270-9888 versus median 321 µl, range 0-6392 in those who remained relapsing-remitting, P = 0.01, adjusted for age and sex). Baseline white matter lesion volume was not associated with worsening disability or transition from relapsing-remitting to secondary progressive multiple sclerosis. Cortical lesion formation is rare in people with stable white matter lesions, even in those with worsening disability. Cortical but not white matter lesion burden predicts disability worsening, suggesting that disability progression is related to long-term effects of cortical lesions that form early in the disease, rather than to ongoing cortical lesion formation.

Automated analysis of gray matter damage in aged mice reveals impaired remyelination in the cuprizone model

Multiple sclerosis is a chronic autoimmune disease of the central nervous system characterized by myelin loss, axonal damage, and glial scar formation. Still, the underlying processes remain unclear, as numerous pathways and factors have been found to be involved in the development and progression of the disease. Therefore, it is of great importance to find suitable animal models as well as reliable methods for their precise and reproducible analysis. Here, we describe the impact of demyelination on clinically relevant gray matter regions of the hippocampus and cerebral cortex, using the previously established cuprizone model for aged mice. We could show that bioinformatic image analysis methods are not only suitable for quantification of cell populations, but also for the assessment of de- and remyelination processes, as numerous objective parameters can be considered for reproducible measurements. After cuprizone-induced demyelination, subsequent remyelination proceeded slowly and remained incomplete in all gray matter areas studied. There were regional differences in the number of mature oligodendrocytes during remyelination suggesting region-specific differences in the factors accounting for remyelination failure, as, even in the presence of oligodendrocytes, remyelination in the cortex was found to be impaired. Upon cuprizone administration, synaptic density and dendritic volume in the gray matter of aged mice decreased. The intensity of synaptophysin staining gradually restored during the subsequent remyelination phase, however the expression of MAP2 did not fully recover. Microgliosis persisted in the gray matter of aged animals throughout the remyelination period, whereas extensive astrogliosis was of short duration as compared to white matter structures. In conclusion, we demonstrate that the application of the cuprizone model in aged mice mimics the impaired regeneration ability seen in human pathogenesis more accurately than commonly used protocols with young mice and therefore provides an urgently needed animal model for the investigation of remyelination failure and remyelination-enhancing therapies.

Current Status of Oral Disease-Modifying Treatment Effects on Cognitive Outcomes in Multiple Sclerosis: A Scoping Review

INTRODUCTION

Cognitive impairment represents one of the most hidden and disabling clinical aspects of multiple sclerosis (MS). In this regard, the major challenges are represented by the need for a comprehensive and standardised cognitive evaluation of each patient, both at disease onset and during follow-up, and by the lack of clear-cut data on the effects of treatments. In the present review, we summarize the current evidence on the effects of the available oral disease-modifying treatments (DMTs) on cognitive outcome measures.

MATERIALS AND METHODS

In this systematised review, we extract all the studies that reported longitudinally acquired cognitive outcome data on oral DMTs in MS patients.

RESULTS

We found 29 studies that evaluated at least one oral DMT, including observational studies, randomised controlled trials, and their extension studies. Most of the studies (n = 20) evaluated sphingosine-1-phosphate (S1P) modulators, while we found seven studies on dimethyl fumarate, six on teriflunomide, and one on cladribine. The most frequently used cognitive outcome measures were SDMT and PASAT. Most of the studies reported substantial stability or mild improvement in cognitive outcomes in a short-time follow-up (duration of most studies ≤2 years). A few studies also reported MRI measures of brain atrophy.

CONCLUSION

Cognitive outcomes were evaluated only in a minority of prospective studies on oral DMTs in MS patients with variable findings. More solid and numerous data are present for the S1P modulators. A standardised cognitive evaluation remains a yet unmet need to better clarify the possible positive effect of oral DMTs on cognition.

Interrater reliability for the detection of cortical lesions on phase-sensitive inversion recovery magnetic resonance imaging in patients with multiple sclerosis

Objective

To assess the reliability of phase-sensitive inversion recovery (PSIR) magnetic resonance imaging (MRI) and its accuracy for determining the topography of demyelinating cortical lesions in patients with multiple sclerosis (MS).

Materials and Methods

This was a cross-sectional study conducted at a tertiary referral center for MS and other demyelinating disorders. We assessed the agreement among three raters for the detection and topographic classification of cortical lesions on fluid-attenuated inversion recovery (FLAIR) and PSIR sequences in patients with MS.

Results

We recruited 71 patients with MS. The PSIR sequences detected 50% more lesions than did the FLAIR sequences. For detecting cortical lesions, the level of interrater agreement was satisfactory, with a mean free-response kappa (κFR) coefficient of 0.60, whereas the mean κFR for the topographic reclassification of the lesions was 0.57. On PSIR sequences, the raters reclassified 366 lesions (20% of the lesions detected on FLAIR sequences), with excellent interrater agreement. There was a significant correlation between the total number of lesions detected on PSIR sequences and the Expanded Disability Status Scale score (ρ = 0.35; p < 0.001).

Conclusion

It seems that PSIR sequences perform better than do FLAIR sequences, with clinically satisfactory interrater agreement, for the detection and topographic classification of cortical lesions. In our sample of patients with MS, the PSIR MRI findings were significantly associated with the disability status, which could influence decisions regarding the treatment of such patients.

Imaging cortical lesions in multiple sclerosis

PURPOSE OF REVIEW

Cortical lesions are an established pathological feature of multiple sclerosis, develop from the earliest disease stages and contribute to disease progression. Here, we discuss current imaging approaches for detecting cortical lesions in vivo and their contribution for improving our understanding of cortical lesion pathogenesis as well as their clinical significance.

RECENT FINDINGS

Although a variable portion of cortical lesions goes undetected at clinical field strength and even at ultra-high field MRI, their evaluation is still clinically relevant. Cortical lesions are important for differential multiple sclerosis (MS) diagnosis, have relevant prognostic value and independently predict disease progression. Some studies also show that cortical lesion assessment could be used as a therapeutic outcome target in clinical trials. Advances in ultra-high field MRI not only allow increased cortical lesion detection in vivo but also the disclosing of some interesting features of cortical lesions related to their pattern of development and evolution as well to the nature of associated pathological changes, which might prove relevant for better understanding the pathogenesis of these lesions.

SUMMARY

Despite some limitations, imaging of cortical lesions is of paramount importance in MS for elucidating disease mechanisms as well as for improving patient management in clinic.

The State of the Art of Pediatric Multiple Sclerosis

Multiple sclerosis (MS) represents a chronic immune-mediated neurodegenerative disease of the central nervous system that generally debuts around the age of 20-30 years. Still, in recent years, MS has been increasingly recognized among the pediatric population, being characterized by several peculiar features compared to adult-onset disease. Unfortunately, the etiology and disease mechanisms are poorly understood, rendering the already limited MS treatment options with uncertain efficacy and safety in pediatric patients. Thus, this review aims to shed some light on the progress in MS therapeutic strategies specifically addressed to children and adolescents. In this regard, the present paper briefly discusses the etiology, risk factors, comorbidities, and diagnosis possibilities for pediatric-onset MS (POMS), further moving to a detailed presentation of current treatment strategies, recent clinical trials, and emerging alternatives. Particularly, promising care solutions are indicated, including new treatment formulations, stem cell therapies, and cognitive training methods.

Accurate Diagnosis of Cortical and Infratentorial Lesions in Multiple Sclerosis Using Accelerated Fluid and White Matter Suppression Imaging

OBJECTIVES

The precise location of multiple sclerosis (MS) cortical lesions can be very challenging at 3 T, yet distinguishing them from subcortical lesions is essential for the diagnosis and prognosis of the disease. Compressed sensing-accelerated fluid and white matter suppression imaging (CS-FLAWS) is a new magnetic resonance imaging sequence derived from magnetization-prepared 2 rapid acquisition gradient echo with promising features for the detection and classification of MS lesions. The objective of this study was to compare the diagnostic performances of CS-FLAWS (evaluated imaging) and phase sensitive inversion recovery (PSIR; reference imaging) for classification of cortical lesions (primary objective) and infratentorial lesions (secondary objective) in MS, in combination with 3-dimensional (3D) double inversion recovery (DIR).

MATERIALS AND METHODS

Prospective 3 T scans (MS first diagnosis or follow-up) acquired between March and August 2021 were retrospectively analyzed. All underwent 3D CS-FLAWS, axial 2D PSIR, and 3D DIR. Double-blinded reading sessions exclusively in axial plane and final consensual reading were performed to assess the number of cortical and infratentorial lesions. Wilcoxon test was used to compare the 2 imaging datasets (FLAWS + DIR and PSIR + DIR), and intraobserver and interobserver agreement was assessed using the intraclass correlation coefficient.

RESULTS

Forty-two patients were analyzed (38 with relapsing-remitting MS, 29 women, 42.7 ± 12.6 years old). Compressed sensing-accelerated FLAWS allowed the identification of 263 cortical lesions versus 251 with PSIR ( P = 0.74) and 123 infratentorial lesions versus 109 with PSIR ( P = 0.63), corresponding to a nonsignificant difference between the 2 sequences. Compressed sensing-accelerated FLAWS exhibited fewer false-negative findings than PSIR either for cortical lesions (1 vs 13; P < 0.01) or infratentorial lesions (1 vs 15; P < 0.01). No false-positive findings were found with any of the 2 sequences. Diagnostic confidence was high for each contrast.

CONCLUSION

Three-dimensional CS-FLAWS is as accurate as 2D PSIR imaging for classification of cortical and infratentorial MS lesions, with fewer false-negative findings, opening the way to a reliable full brain MS exploration in a clinically acceptable duration (5 minutes 15 seconds).

An investigation of the association between focal damage and global network properties in cognitively impaired and cognitively preserved patients with multiple sclerosis

Introduction

The presence of focal cortical and white matter damage in patients with multiple sclerosis (pwMS) might lead to specific alterations in brain networks that are associated with cognitive impairment. We applied microstructure-weighted connectomes to investigate (i) the relationship between global network metrics and information processing speed in pwMS, and (ii) whether the disruption provoked by focal lesions on global network metrics is associated to patients' information processing speed.

Materials and methods

Sixty-eight pwMS and 92 healthy controls (HC) underwent neuropsychological examination and 3T brain MRI including multishell diffusion (dMRI), 3D FLAIR, and MP2RAGE. Whole-brain deterministic tractography and connectometry were performed on dMRI. Connectomes were obtained using the Spherical Mean Technique and were weighted for the intracellular fraction. We identified white matter lesions and cortical lesions on 3D FLAIR and MP2RAGE images, respectively. PwMS were subdivided into cognitively preserved (CPMS) and cognitively impaired (CIMS) using the Symbol Digit Modalities Test (SDMT) z-score at cut-off value of -1.5 standard deviations. Statistical analyses were performed using robust linear models with age, gender, and years of education as covariates, followed by correction for multiple testing.

Results

Out of 68 pwMS, 18 were CIMS and 50 were CPMS. We found significant changes in all global network metrics in pwMS vs HC (p < 0.05), except for modularity. All global network metrics were positively correlated with SDMT, except for modularity which showed an inverse correlation. Cortical, leukocortical, and periventricular lesion volumes significantly influenced the relationship between (i) network density and information processing speed and (ii) modularity and information processing speed in pwMS. Interestingly, this was not the case, when an exploratory analysis was performed in the subgroup of CIMS patients.

Discussion

Our study showed that cortical (especially leukocortical) and periventricular lesions affect the relationship between global network metrics and information processing speed in pwMS. Our data also suggest that in CIMS patients increased focal cortical and periventricular damage does not linearly affect the relationship between network properties and SDMT, suggesting that other mechanisms (e.g. disruption of local networks, loss of compensatory processes) might be responsible for the development of processing speed deficits.

Improved prediction of early cognitive impairment in multiple sclerosis combining blood and imaging biomarkers

Disability in multiple sclerosis is generally classified by sensory and motor symptoms, yet cognitive impairment has been identified as a frequent manifestation already in the early disease stages. Imaging- and more recently blood-based biomarkers have become increasingly important for understanding cognitive decline associated with multiple sclerosis. Thus, we sought to determine the prognostic utility of serum neurofilament light chain levels alone and in combination with MRI markers by examining their ability to predict cognitive impairment in early multiple sclerosis. A comprehensive and detailed assessment of 152 early multiple sclerosis patients (Expanded Disability Status Scale: 1.3 ± 1.2, mean age: 33.0 ± 10.0 years) was performed, which included serum neurofilament light chain measurement, MRI markers (i.e. T₂-hyperintense lesion volume and grey matter volume) acquisition and completion of a set of cognitive tests (Symbol Digits Modalities Test, Paced Auditory Serial Addition Test, Verbal Learning and Memory Test) and mood questionnaires (Hospital Anxiety and Depression scale, Fatigue Scale for Motor and Cognitive Functions). Support vector regression, a branch of unsupervised machine learning, was applied to test serum neurofilament light chain and combination models of biomarkers for the prediction of neuropsychological test performance. The support vector regression results were validated in a replication cohort of 101 early multiple sclerosis patients (Expanded Disability Status Scale: 1.1 ± 1.2, mean age: 34.4 ± 10.6 years). Higher serum neurofilament light chain levels were associated with worse Symbol Digits Modalities Test scores after adjusting for age, sex Expanded Disability Status Scale, disease duration and disease-modifying therapy (B = −0.561; SE = 0.192; P = 0.004; 95% CI = −0.940 to −0.182). Besides this association, serum neurofilament light chain levels were not linked to any other cognitive or mood measures (all P-values > 0.05). The tripartite combination of serum neurofilament light chain levels, lesion volume and grey matter volume showed a cross-validated accuracy of 88.7% (90.8% in the replication cohort) in predicting Symbol Digits Modalities Test performance in the support vector regression approach, and outperformed each single biomarker (accuracy range: 68.6–75.6% and 68.9–77.8% in the replication cohort), as well as the dual biomarker combinations (accuracy range: 71.8–82.3% and 72.6–85.6% in the replication cohort). Taken together, early neuro-axonal loss reflects worse information processing speed, the key deficit underlying cognitive dysfunction in multiple sclerosis. Our findings demonstrate that combining blood and imaging measures improves the accuracy of predicting cognitive impairment, highlighting the clinical utility of cross-modal biomarkers in multiple sclerosis.

Symptom Interconnectivity in Multiple Sclerosis: A Narrative Review of Potential Underlying Biological Disease Processes

Introduction

Fatigue, cognitive impairment, depression, and pain are highly prevalent symptoms in multiple sclerosis (MS). These often co-occur and may be explained by a common etiology. By reviewing existing literature, we aimed to identify potential underlying biological processes implicated in the interconnectivity between these symptoms.

Methods

A literature search was conducted to identify articles reporting research into the biological mechanisms responsible for the manifestation of fatigue, cognitive impairment, depression, and pain in MS. PubMed was used to search for articles published from July 2011 to July 2021. We reviewed and assessed findings from the literature to identify biological processes common to the symptoms of interest.

Results

Of 693 articles identified from the search, 252 were selected following screening of titles and abstracts and assessing reference lists of review articles. Four biological processes linked with two or more of the symptoms of interest were frequently identified from the literature: (1) direct neuroanatomical changes to brain regions linked with symptoms of interest (e.g., thalamic injury associated with cognitive impairment, fatigue, and depression), (2) pro-inflammatory cytokines associated with so-called ‘sickness behavior,’ including manifestation of fatigue, transient cognitive impairment, depression, and pain, (3) dysregulation of monoaminergic pathways leading to depressive symptoms and fatigue, and (4) hyperactivity of the hypothalamic–pituitary-adrenal (HPA) axis as a result of pro-inflammatory cytokines promoting the release of brain noradrenaline, serotonin, and tryptophan, which is associated with symptoms of depression and cognitive impairment.

Conclusion

The co-occurrence of fatigue, cognitive impairment, depression, and pain in MS appears to be associated with a common set of etiological factors, namely neuroanatomical changes, pro-inflammatory cytokines, dysregulation of monoaminergic pathways, and a hyperactive HPA axis. This association of symptoms and biological processes has important implications for disease management strategies and, eventually, could help find a common therapeutic pathway that will impact both inflammation and neuroprotection.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-022-00368-2.

Short-Range Structural Connections Are More Severely Damaged in Early-Stage MS

BACKGROUND AND PURPOSE

Long-range connections are more severely damaged and relevant for cognition in long-standing MS. However, the evolution of such coordinated network damage in patients with MS is unclear. We investigated whether short- and long-range structural connections sustained equal damage in early-stage MS.

MATERIALS AND METHODS

Sixteen patients with early-stage MS and 17 healthy controls were scanned by high-resolution, multishell diffusion imaging on 7T MR imaging and assessed cognitively. We investigated macrostructural properties in short- and long-range fibers and of microstructural metrics derived from 2 quantitative diffusion MR imaging models: DTI and neurite orientation dispersion and density imaging.

RESULTS

Patients had significant WM integrity damage-that is, higher radial diffusivity and a lower intracellular volume fraction in the focal WM lesions. Compared with the healthy controls, the patients had noticeable microstructure changes in both short- and long-range fibers, including increased radial diffusivity, mean diffusivity, and axial diffusivity. Z scores further indicated greater damage in the short-range fibers than in the long-range fibers.

CONCLUSIONS

Our findings demonstrate that more severe demyelination preceding axonal degeneration occurs in short-range connections but not in long-range connections in early-stage MS, suggesting the possibility that there are cortical lesions that are undetectable by current MR imaging.

Comparing diagnostic criteria for the diagnosis of neurocognitive disorders in multiple sclerosis

BACKGROUND

People with multiple sclerosis (MS) commonly experience cognitive impairment associated with the disease, but there is currently no agreed-upon operational definition for identifying the presence of that impairment, in either research or clinic contexts. The International MS Cognition Society (IMSCOGS) established a task force to begin to examine this issue and this paper represents the results of an initial pilot investigation. The aim of this paper was to compare two criterion sets to determine how to identify cognitive impairment among people with MS: the general Diagnostic and Statistical Manual (DSM-5) Criteria for neurocognitive disorders and criteria derived from existing MS research (scores in two domains fall 1.5 standard deviations below normative controls).

METHODS

Two hundred and ten people with MS presented for a brief cognitive evaluation in an MS Multidisciplinary Clinic at a midwestern academic medical center in the United States. Participants were generally middle aged (average 51.5 years), female (73.8%), and white (93.3%). McNemar's test was computed to compare the number of individuals whose cognitive test score performance was deemed cognitively normal, mildly impaired, or more significantly impaired.

RESULTS

DSM-5 criteria classified 87.2% of the sample as cognitively impaired, where 66.7% were more mildly impaired and 20.5% more significantly impaired. By contrast, research-based criteria classified 63.3% of the sample as cognitively impaired, with 49.5% as mildly impaired and 13.8% as more significantly impaired.

CONCLUSIONS

These findings indicate that compared to research criteria, the DSM-5 criteria classified far more people with MS as having cognitive impairment secondary to the disease. The paper discusses the potential benefits and drawbacks of the two diagnostic methods, highlighting that more work will be needed in order to establish a standardized and validated method for characterizing these impairments.

Correlation of cortical lesions of multiple sclerosis at double inversion recovery with cognition screening scores

Background

Multiple sclerosis is a chronic inflammatory disease affecting both white and gray matters of the central nervous system. It has been approved that the degree of gray matter involvement is closely associated with the degree of physical disability and the extent of cognitive impairment. Thus, it is necessary to incorporate widely available simple methods for neurocognitive evaluation and gray matter detection in the periodic assessment of MS patients that will influence treatment decisions.

Objectives

To assess the correlation of cortical lesions of multiple sclerosis (MS) at double inversion recovery (DIR) with cognition screening scores

Methods

This study was conducted on 30 patients with MS with an average age of 31.3±13.6 years. All of them underwent MRI and clinical assessment with the calculation of Expanded Disability Status Scale (EDSS), Montreal Cognitive Assessment (MoCA), and Symbol Digit Modality Test (SDMT) scores. The image analysis was performed by 2 reviewers for cortical lesion number, shape, and subtypes, and total lesion load.

Results

Both MoCA and SDMT scales had a significant inverse correlation with cortical lesions number (r=− 0.68, − 0.72) respectively and total lesion load (r=− 0.53, − 0.65) respectively. Besides, there was a significant inverse correlation between the MoCA test, varied cortical subtypes: leukocortical, juxtacortical, and intracortical subtypes (r = − 0.63, − 0.56, − 0.52) respectively, and different cortical lesion shapes: oval, wedge, and curvilinear shaped (r = − 0.62, − 0.69, − 0.49) respectively. As well, the SDMT scale showed a significant inverse correlation with varied cortical subtypes: intracortical, leukocortical, and juxtacortical subtypes (r = − 0.63, − 0.61, − 0.57) respectively, and different cortical lesion shapes: oval, curvilinear, and wedge shaped (r = − 0.61, − 0.59, − 0.46) respectively. Interestingly, there was an excellent inter-observer correlation of cortical lesion number (r = 0.96), total lesion load (r = 0.95), subtypes of cortical lesion (r = 0.94), and cortical lesion shapes (r = 0.77).

Conclusion

We concluded that DIR can detect cortical lesions of MS, and MRI findings were well-correlated with cognitive dysfunction in these patients.

Multi-layer analysis of quantitative 7 T magnetic resonance imaging in the cortex of multiple sclerosis patients reveals pathology associated with disability

BACKGROUND

Cortical demyelination is a relevant aspect of tissue damage in multiple sclerosis (MS). Microstructural changes may affect each layer in the cortex differently.

OBJECTIVES

To evaluate the sensitivity of quantitative magnetic resonance imaging (qMRI) measurements on cortical layers as clinically accessible biomarkers of grey matter (GM) pathology.

METHODS

Forty-five participants with MS underwent 7 T magnetic resonance imaging (MRI) of the brain. Magnetization prepared two rapid acquisition gradient echoes (MP2RAGE) was processed for T1-weighted images and a T1 map. Multi-echo gradient echo images were processed for quantitative susceptibility and R2* maps. Cortical GM volumes were segmented into four cortical layers, and relaxometry metrics were calculated within and between these layers.

RESULTS

Significant correlations were found for disability scales and multi-layer metrics, for example, Expanded Disability Status Scale (EDSS) and peak height (PH) in the subpial (T1: ρ = -0.372, p < 0.050) and inner (R2*: ρ = -0.359, p < 0.050) cortical layers. Multivariate regression showed interdependency between atrophy and cortical metrics in some instances, but an independent relationship between cortical metrics and disability in others.

CONCLUSION

Cortical layer 7 T qMRI analyses reveal layer-specific relationships with disability in MS and allow emergence of clinically relevant associations that are hidden when analysing the full cortex.

Pain, cognition and disability in advanced multiple sclerosis

OBJECTIVES

In patients with multiple sclerosis (MS), a relationship between physical disability and pain has been observed. In addition a relationship between physical disability and cognition in MS has been suggested. However, cognitive functions and pain appear not to be correlated in MS patients. Therefore, we examined whether a possible relationship between pain and cognitive functioning may exist, and if so, if such a relationship is mediated by physical disability.

METHODS

Forty-five MS patients with chronic pain, and in an advanced stage of the disease were included. Physical disabilities were assessed by the Expanded Disability Status Scale (EDSS). Episodic memory was assessed by means of the Eight Words test, and Face and Picture Recognition. Executive functions (EF) were examined by Digit Span Backward for working memory, and the Rule Shift Cards and Category Fluency test for cognitive flexibility. Pain Intensity and Pain Affect were assessed by means of visual analogue scales and one verbal pain scale and mood (depression, anxiety) by the Beck Depression Inventory and the Symptom Check List (SCL-90). The research questions were analyzed by means of regression analyses and the Sobel test for mediation.

RESULTS

A significant relationship was found between Pain Affect and EF, but that relationship was not mediated by physical disabilities (EDSS). In addition, Pain Intensity and EF showed a significant relationship but only in combination with physical disabilities (EDSS). Finally, mood was related to pain affect.

DISCUSSION

The findings suggest that the lower the EF, exclusively or in combination with more physical disabilities, the more the patient may suffer from pain.

IMPLICATIONS

The more one is cognitively and physically impaired, the more one might suffer from pain, and, the less one is able to communicate pain. The latter could put MS patients at risk for underdiagnosing and undertreatment of pain.

Imaging cortical multiple sclerosis lesions with ultra-high field MRI

BACKGROUND

Cortical lesions are abundant in multiple sclerosis (MS), yet difficult to visualize in vivo. Ultra-high field (UHF) MRI at 7 T and above provides technological advances suited to optimize the detection of cortical lesions in MS.

PURPOSE

To provide a narrative and quantitative systematic review of the literature on UHF MRI of cortical lesions in MS.

METHODS

A systematic search of all literature on UHF MRI of cortical lesions in MS published before September 2020. Quantitative outcome measures included cortical lesion numbers reported using 3 T and 7 T MRI and between 7 T MRI sequences, along with sensitivity of UHF MRI towards cortical lesions verified by histopathology.

RESULTS

7 T MRI detected on average 52 ± 26% (mean ± 95% confidence interval) more cortical lesions than the best performing image contrast at 3 T, with the largest increase in type II-IV intracortical lesion detection. Across all studies, the mean cortical lesion number was 17 ± 6 per patient. In progressive MS cohorts, approximately four times more cortical lesions were reported than in CIS/early RRMS, and RRMS. Yet, there was no difference in lesion type ratio between these MS subtypes. Furthermore, superiority of one MRI sequence over another could not be established from available data. Post-mortem lesion detection with UHF MRI agreed only modestly with pathological examinations. Mean pro- and retrospective sensitivity was 33 ± 6% and 71 ± 10%, respectively, with the highest sensitivity towards type I and type IV lesions.

CONCLUSION

UHF MRI improves cortical lesion detection in MS considerably compared to 3 T MRI, particularly for type II-IV lesions. Despite modest sensitivity, 7 T MRI is still capable of visualizing all aspects of cortical lesion pathology and could potentially aid clinicians in diagnosing and monitoring MS, and progressive MS in particular. However, standardization of acquisition and segmentation protocols is needed.

Ultra-high field 7 T imaging in multiple sclerosis

PURPOSE OF REVIEW

Ultra-high field 7 T MRI has multiple applications for the in vivo characterization of the heterogeneous aspects underlying multiple sclerosis including the identification of cortical lesions, characterization of the different types of white matter plaques, evaluation of structures difficult to assess with conventional MRI (thalamus, cerebellum, spinal cord, meninges).

RECENT FINDINGS

The sensitivity of cortical lesion detection at 7 T is twice than at lower field MRI, especially for subpial lesions, the most common cortical lesion type in multiple sclerosis. Cortical lesion load accrual is independent of that in the white matter and predicts disability progression.Seven Tesla MRI provides details on tissue microstructure that can be used to improve white matter lesion characterization. These include the presence of a central vein, whose identification can be used to improve multiple sclerosis diagnosis, or the appearance of an iron-rich paramagnetic rim on susceptibility-weighted images, which corresponds to iron-rich microglia at the periphery of slow expanding lesions. Improvements in cerebellar and spinal cord tissue delineation and lesion characterization have also been demonstrated.

SUMMARY

Imaging at 7 T allows assessing more comprehensively the complementary pathophysiological aspects of multiple sclerosis, opening up novel perspectives for clinical and therapeutics evaluation.

Histopathology-validated recommendations for cortical lesion imaging in multiple sclerosis

Cortical demyelinating lesions are clinically important in multiple sclerosis, but notoriously difficult to visualize with MRI. At clinical field strengths, double inversion recovery MRI is most sensitive, but still only detects 18% of all histopathologically validated cortical lesions. More recently, phase-sensitive inversion recovery was suggested to have a higher sensitivity than double inversion recovery, although this claim was not histopathologically validated. Therefore, this retrospective study aimed to provide clarity on this matter by identifying which MRI sequence best detects histopathologically-validated cortical lesions at clinical field strength, by comparing sensitivity and specificity of the thus far most commonly used MRI sequences, which are T₂, fluid-attenuated inversion recovery (FLAIR), double inversion recovery and phase-sensitive inversion recovery. Post-mortem MRI was performed on non-fixed coronal hemispheric brain slices of 23 patients with progressive multiple sclerosis directly after autopsy, at 3 T, using T₁ and proton-density/T₂-weighted, as well as FLAIR, double inversion recovery and phase-sensitive inversion recovery sequences. A total of 93 cortical tissue blocks were sampled from these slices. Blinded to histopathology, all MRI sequences were consensus scored for cortical lesions. Subsequently, tissue samples were stained for proteolipid protein (myelin) and scored for cortical lesion types I–IV (mixed grey matter/white matter, intracortical, subpial and cortex-spanning lesions, respectively). MRI scores were compared to histopathological scores to calculate sensitivity and specificity per sequence. Next, a retrospective (unblinded) scoring was performed to explore maximum scoring potential per sequence. Histopathologically, 224 cortical lesions were detected, of which the majority were subpial. In a mixed model, sensitivity of T₁, proton-density/T₂, FLAIR, double inversion recovery and phase-sensitive inversion recovery was 8.9%, 5.4%, 5.4%, 22.8% and 23.7%, respectively (20, 12, 12, 51 and 53 cortical lesions). Specificity of the prospective scoring was 80.0%, 75.0%, 80.0%, 91.1% and 88.3%. Sensitivity and specificity did not significantly differ between double inversion recovery and phase-sensitive inversion recovery, while phase-sensitive inversion recovery identified more lesions than double inversion recovery upon retrospective analysis (126 versus 95; P < 0.001). We conclude that, at 3 T, double inversion recovery and phase-sensitive inversion recovery sequences outperform conventional sequences T₁, proton-density/T₂ and FLAIR. While their overall sensitivity does not exceed 25%, double inversion recovery and phase-sensitive inversion recovery are highly pathologically specific when using existing scoring criteria and their use is recommended for optimal cortical lesion assessment in multiple sclerosis.

Insights into the role of B cells in the cortical pathology of Multiple sclerosis: evidence from animal models and patients

Multiple sclerosis (MS) is a chronic, immune-mediated disease of the central nervous system (CNS) that affects both white and gray matter. Although it has been traditionally considered as a T cell mediated disease, the role of B cell in MS pathology has become a topic of great research interest. Cortical lesions, key feature of the progressive forms of MS, are involved in cognitive impairment and worsening of the patients' outcome. These lesions present pathognomonic hallmarks, such as: absence of blood-brain barrier (BBB) disruption, limited inflammatory events, reactive microglia, neurodegeneration, demyelination and meningeal inflammation. B cells located in the meninges, either as part of diffuse inflammation or as part of follicle-like structures, are strongly associated with cortical damage. The function of CD20-expressing B cells in MS is further highlighted by the success of specific therapies using anti-CD20 antibodies. The possible roles of B cells in pathology go beyond their ability to produce antibodies, as they also present antigens to T cells, secrete cytokines (both pathogenic and protective) within the CNS to modulate T and myeloid cell functions, and are involved in meningeal inflammation. Here, we will review the contributions of B cells to the pathogenesis of meningeal inflammation and cortical lesions in MS patients as well as in preclinical animal models.

Training the brain: could it improve multiple sclerosis treatment?

Multiple sclerosis (MS) is a neurological disease characterized by neuroinflammation, demyelination and axonal degeneration along with loss of function in the central nervous system. For many years, research in MS has focused on the efficacy of pharmacological treatments. However, during the last years, many publications have been dedicated to the study of the efficacy of non-pharmacological strategies, such as physical exercise and cognitive training. Beneficial effects of the combination of both strategies on cognitive function have been described in both ageing adults and patients with neurodegenerative diseases, such as MS. The analysis of combining both physical and cognitive stimulation can be summarized by the environmental enrichment (EE) experiments, which are more suitable for animal models. EE refers to housing conditions consisting of exercise and cognitive and social stimulation. In this review, we will summarize the available studies that describe the influence of EE in both MS patients and MS animal models.

Cognitive impairment in multiple sclerosis: clinical management, MRI, and therapeutic avenues

Multiple sclerosis is a chronic, demyelinating disease of the CNS. Cognitive impairment is a sometimes neglected, yet common, sign and symptom with a profound effect on instrumental activities of daily living. The prevalence of cognitive impairment in multiple sclerosis varies across the lifespan and might be difficult to distinguish from other causes in older age. MRI studies show that widespread changes to brain networks contribute to cognitive dysfunction, and grey matter atrophy is an early sign of potential future cognitive decline. Neuropsychological research suggests that cognitive processing speed and episodic memory are the most frequently affected cognitive domains. Narrowing evaluation to these core areas permits brief, routine assessment in the clinical setting. Owing to its brevity, reliability, and sensitivity, the Symbol Digit Modalities Test, or its computer-based analogues, can be used to monitor episodes of acute disease activity. The Symbol Digit Modalities Test can also be used in clinical trials, and data increasingly show that cognitive processing speed and memory are amenable to cognitive training interventions.

Frontal aslant tracts as correlates of lexical retrieval in MS

INTRODUCTION

Previous studies reveal that a newly described white matter pathway, the frontal aslant tract (FAT), connecting inferior and superior frontal gyri has a role in speech and language functions. We explored the role of this tract in a phonemic and semantic fluency tasks in a cohort of multiple sclerosis patients diagnosed with cognitive impairment.

METHODS

Thirty-five MS patients with varying degrees of cognitive impairment underwent diffusion tensor imaging and the Controlled Associated Word Test. Fractional anisotropy (FA) of FAT and arcuate fasciculus (AF) were obtained through a supervised, atlas-based tissue segmentation and parcellation method. Phonemic and semantic fluency scores were obtained from COWAT. We ran a multivariate regression model, and partial correlation analyses adjusted for age, education, and lesion load, and corrected for multiple comparisons. False discovery rate (FDR) was used for the correction of multiple comparisons.

RESULTS

Bilateral FAT FA showed significant association with phonemic verbal fluency task (Left; r = 0.46, p = 0.0058 and right; r = 0.46, p = 0.0059) but not semantic fluency task and this relation remained significant after FDR correction (p = 0.02 bilaterally). Although left AF showed some significant association with phonemic fluency task, this relation was insignificant after FDR correction.

CONCLUSION

We show that bilateral FAT are correlates of phonemic verbal fluency task but not semantic in an MS cohort with cognitive impairment. This finding suggests that FAT is more specialized in lexical retrieval function as semantic fluency test encompasses all the functions except the lexical retrieval.

Cognitive impairment in early MS: contribution of white matter lesions, deep grey matter atrophy, and cortical atrophy

Background

Cognitive impairment (CI) is a frequent and debilitating symptom in MS. To better understand the neural bases of CI in MS, this magnetic resonance imaging (MRI) study aimed to identify and quantify related structural brain changes and to investigate their relation to each other.

Methods

We studied 51 patients with CI and 391 patients with cognitive preservation (CP). We analyzed three-dimensional T1-weighted and FLAIR scans at 3 Tesla. We determined mean cortical thickness as well as volumes of cortical grey matter (GM), deep GM including thalamus, cerebellar cortex, white matter, corpus callosum, and white matter lesions (WML). We also analyzed GM across the whole brain by voxel-wise and surface-based techniques.

Results

Mean disease duration was 5 years. Comparing MS patients with CI and CP, we found higher volumes of WML, lower volumes of deep and cortical GM structures, and lower volumes of the corpus callosum (all corrected p values < 0.05). Effect sizes were largest for WML and thalamic volume (standardized ß values 0.25 and − 0.25). By logistic regression analysis including both WML and thalamic volume, we found a significant effect only for WML volume. Inclusion of the interaction term of WML and thalamic volume increased the model fit and revealed a highly significant interaction of WML and thalamic volume. Moreover, voxel-wise and surface-based comparisons of MS patients with CI and CP showed regional atrophy of both deep and cortical GM independent of WML volume and overall disability, but effect sizes were lower.

Conclusion

Although several mechanisms contribute to CI already in the early stage of MS, WML seem to be the main driver with thalamic atrophy primarily intensifying this effect.

Contribution of cortical lesions to cognitive impairment in Japanese patients with multiple sclerosis

Cortical lesions (CLs) have a low prevalence and are associated with physical disabilities in Japanese patients with multiple sclerosis (MS). However, the contribution of CLs to cognitive impairment remains unclear in Asian MS. Sixty-one prospectively enrolled MS patients underwent three-dimensional double inversion recovery MR imaging, the Brief Repeatable Battery of Neuropsychological Tests (BRB-N), the Apathy Scale (AS), the Fatigue Questionnaire (FQ), and the Hospital Anxiety and Depression Scale (HADS) within a 1-week period. The cognitive impairment index (CII) score was calculated to measure patients’ overall cognitive impairment. MS patients with CLs had poorer scores than those without CLs in most BRB-N tests, but scored comparably in the FQ, AS, and HADS. The number of CLs correlated negatively with all BRB-N test scores and positively with total CII scores. Leukocortical lesions were more extensively associated with cognitive dysfunction in various domains than intracortical lesions. Stepwise multiple regression analysis revealed that potential confounding factors for the highest quartile of CII score were the number of CLs (odds ratio 2.38, p = 0.0070) and the Expanded Disability Severity Scale score (odds ratio 2.13, p = 0.0003). Our results demonstrate that the presence and number of CLs are robustly associated with cognitive dysfunction in Asian MS patients.

Environmental enrichment improves cognitive symptoms and pathological features in a focal model of cortical damage of multiple sclerosis

Multiple Sclerosis (MS) is a neuroinflammatory disease affecting white and grey matter, it is characterized by demyelination, axonal degeneration along with loss of motor, sensitive and cognitive functions. MS is a heterogeneous disease that displays different clinical courses: relapsing/remitting MS (RRMS), and MS progressive forms: primary progressive (PPMS) and secondary progressive (SPMS). Cortical damage in the progressive MS forms has considerable clinical relevance due to its association with cognitive impairment and disability progression in patients. One treatment is available for the progressive forms of the disease, but none are specific for cognitive deficits. We developed an animal model that reflects most of the characteristics of the cortical damage, such as cortical neuroinflammation, demyelination, neurodegeneration and meningeal inflammation, which was associated with cognitive impairment. Cognitive rehabilitation, exercise and social support have begun to be evaluated in patients and animal models of neurodegenerative diseases. Environmental enrichment (EE) provides exercise as well as cognitive and social stimulation. EE has been demonstrated to exert positive effects on cognitive domains, such as learning and memory, and improving anxiety-like symptoms. We proposed to study the effect of EE on peripherally stimulated cortical lesion induced by the long term expression of interleukin IL-1β (IL-1β) in adult rats. Here, we demonstrated that EE: 1) reduces the peripheral inflammatory response to the stimulus, 2) ameliorates cognitive deficits and anxiety-like symptoms, 3) modulates neurodegeneration, demyelination and glial activation, 4) regulates neuroinflammation by reducing the expression of pro-inflammatory cytokines and enhancing the expression of anti-inflammatory ones. Our findings correlate with the fact that EE housing could be considered an effective non- pharmacological therapeutic agent that can synergistically aid in the rehabilitation of the disease.

7T quantitative magnetization transfer (qMT) of cortical gray matter in multiple sclerosis correlates with cognitive impairment

Cognitive impairment (CI) is a major manifestation of multiple sclerosis (MS) and is responsible for extensively hindering patient quality of life. Cortical gray matter (cGM) damage is a significant contributor to CI, but is poorly characterized by conventional MRI let alone with quantitative MRI, such as quantitative magnetization transfer (qMT). Here we employed high-resolution qMT at 7T via the selective inversion recovery (SIR) method, which provides tissue-specific indices of tissue macromolecular content, such as the pool size ratio (PSR) and the rate of MT exchange (kmf). These indices could represent expected demyelination that occurs in the presence of gray matter damage. We utilized selective inversion recovery (SIR) qMT which provides a low SAR estimate of macromolecular-bulk water interactions using a tailored, B1 and B0 robust inversion recovery (IR) sequence acquired at multiple inversion times (TI) at 7T and fit to a two-pool model of magnetization exchange. Using this sequence, we evaluated qMT indices across relapsing-remitting multiple sclerosis patients (N = 19) and healthy volunteers (N = 37) and derived related associations with neuropsychological measures of cognitive impairment. We found a significant reduction in k_mf in cGM of MS patients (15.5%, p = 0.002), unique association with EDSS (ρ = -0.922, p = 0.0001), and strong correlation with cognitive performance (ρ = -0.602, p = 0.0082). Together these findings indicate that the rate of MT exchange (k_mf) may be a significant biomarker of cGM damage relating to CI in MS.

Cortical and meningeal pathology in progressive multiple sclerosis: a new therapeutic target?

Multiple sclerosis (MS) is an inflammatory and neurodegenerative disease that involves an intricate interaction between the central nervous system and the immune system. Nevertheless, its etiology is still unknown. MS exhibits different clinical courses: recurrent episodes with remission periods ('relapsing-remitting') that can evolve to a 'secondary progressive' form or persistent progression from the onset of the disease ('primary progressive'). The discovery of an effective treatment and cure has been hampered due to the pathological and clinical heterogeneity of the disease. Historically, MS has been considered as a disease exclusively of white matter. However, patients with progressive forms of MS present with cortical lesions associated with meningeal inflammation along with physical and cognitive disabilities. The pathogenesis of the cortical lesions has not yet been fully described. Animal models that represent both the cortical and meningeal pathologies will be critical in addressing MS pathogenesis as well as the design of specific treatments. In this review, we will address the state-of-the-art diagnostic and therapeutic alternatives and the development of strategies to discover new therapeutic approaches, especially for the progressive forms.

Detection of Leukocortical Lesions in Multiple Sclerosis and Their Association with Physical and Cognitive Impairment: A Comparison of Conventional and Synthetic Phase-Sensitive Inversion Recovery MRI

BACKGROUND AND PURPOSE

Cortical lesions are common in multiple sclerosis and are included in the latest diagnostic criteria. The limited sensitivity of cortical MS lesions on conventional MR imaging can be improved by phase-sensitive inversion recovery. Synthetic MR imaging could provide phase-sensitive inversion recovery without additional scanning, but the use of synthetic phase-sensitive inversion recovery remains to be validated. We aimed to compare the ability and clinical value of detecting leukocortical lesions with conventional and synthetic phase-sensitive inversion recovery in MS.

MATERIALS AND METHODS

Twenty-one patients with MS prospectively underwent conventional and synthetic phase-sensitive inversion recovery, 3D T1-weighted, and T2 FLAIR imaging. Two neuroradiologists independently performed blinded phase-sensitive inversion recovery lesion assessments; a consensus rating with all sequences was considered the criterion standard. Lesion volumes were segmented. All participants underwent standardized cognitive and physical examinations and Fatigue Severity Scale assessment. Results were analyzed with multiple linear regressions.

RESULTS

Interrater and criterion standard agreement for leukocortical lesions was excellent for both conventional and synthetic phase-sensitive inversion recovery (intraclass correlation coefficient = 0.79-0.97). Leukocortical lesion volumes for both sequences were associated with lower information-processing speed (P ≤ .01) and verbal fluency (P ≤ .02). Both phase-sensitive inversion recovery sequences showed a positive effect on the association when combining volumes of leukocortical lesions and white matter lesions with information-processing speed (P ≤ .005) and verbal fluency (P ≤ .03). No associations were found between leukocortical lesion volumes and physical disability or fatigue.

CONCLUSIONS

Synthetic and conventional phase-sensitive inversion recovery have a sensitivity similar to that of leukocortical MS lesions. The detected leukocortical lesions are associated with cognitive dysfunction and thus provide clinically relevant information, which encourages assessment of cortical MS involvement at conventional field strengths.

[What do we know about the pathology of gray matter in multiple sclerosis]

The emergence of modern methods of immunohistochemistry and further development of MRI has led to a deeper understanding of gray matter (GM) pathology in multiple sclerosis (MS). GM involvement can be extensive including both demyelination (cortical lesions) and neuroaxonal damage. The mechanisms of GM damage in MS remain insufficiently studied. There are two concepts: the lesion of GM is primary and is paralleled by changes in white matter (WM), or secondary, i.e. it is a consequence of the pathological process in WM. More research into GM pathology using the latest MRI techniques will contribute to the understanding of pathological changes in both cortical and subcortical GM.

Correlation between cortical lesions and cognitive impairment in multiple sclerosis

OBJECTIVES

Gray matter (GM) damage is well known as a fundamental aspect of multiple sclerosis (MS). Above all, cortical lesions (CLs) burden, detectable at MRI with double inversion recovery (DIR) sequences, has been demonstrated to correlate with cognitive impairment (CI). The aim of this study was to investigate the role of CLs number in predicting CI in a cohort of patients with MS in a clinical practice setting.

MATERIALS AND METHODS

Thirty consecutive patients with MS presenting CLs (CL+) at high-field (3.0 T) MRI 3D-DIR sequences and an even group of MS patients without CLs (CL-) as a control, were investigated with the Rao Brief Repeatable Battery of Neuropsychological Tests (BRB), Version A. Total and lobar CLs number were computed in CL+ patients.

RESULTS

Among the sixty patients with MS enrolled, forty-seven (78.3%) had a relapsing-remitting course, while thirteen (21.7%) a progressive one, eleven secondary progressive, and two primary progressive. Compared to CL-, CL+ patients had a greater proportion of progressive forms (p = .03). The most affected region was the frontal lobe (73.3% of patients), followed by temporal and parietal ones (both 60.0%). Multivariate (logistic regression) analysis revealed a significant correlation between total CLs number and the presence of mild cognitive impairment defined as pathologic score in at least one BRB test (p = .04); it was also correlated with deficit at PASAT 3 (p = .05) and Stroop Test (p = .02).

CONCLUSIONS

We confirmed CLs number, evaluated with a technique quite commonly available in clinical practice, as a predictive factor of CI in patients with MS, in order to improve the diagnosis and management of CI and monitor potential neuroprotective effects of therapies.

Quantitative Limbic System Mapping of Main Cognitive Domains in Multiple Sclerosis

Background and objective

Cognitive impairment (CI) is common in multiple sclerosis (MS), but underlying mechanisms and their imaging correlates are not completely understood. The gray and white matter structures of the limbic system (LS) play crucial roles in different aspects of cognition. To investigate their role in MS related CI, and since a detailed evaluations are lacking in the literature, we used a comprehensive neuroimaging approach to evaluate CI’s correlations with the main components of the LS.

Methods

Ten non-cognitively impaired MS patients and 30 MS patients with diagnosed CI, who underwent a comprehensive neuropsychological evaluation were included in the analysis. Microstructural integrity, volumetry of main limbic gray and white matter structures and cortical thickness were assessed for associations with CI.

Results

Fornix and cingulum/cingulate cortices were found to be the strongest correlates of CI in MS. As expected, LS’ gray and white matter structures were involved in various cognitive functions. Uncinate fasciculi showed significant correlation with verbal and visuospatial learning and memory, phonemic and semantic fluency; hippocampi with visuospatial skills, phonemic and semantic fluency, executive functions, and processing speed; thalami with verbal learning, visuospatial skills, semantic fluency; and amygdala with verbal recognition discrimination.

Conclusion

This comprehensive neuroimaging approach elucidated the role of the main limbic structures in cognitive functions associated with MS-related CI.

Clinical significance of cortical lesions in patients with multiple sclerosis: A neuropsychological and neuroimaging study

INTRODUCTION

This study aims to investigate the association between the presence and frequency of cortical lesions (CLs), and the clinical and psychological features of multiple sclerosis (MS).

METHODS

A total of 19 patients with MS were examined using double inversion recovery (DIR) sequences with 3T magnetic resonance imaging (MRI) and classified into two groups: CL and non-CL. In-house software was used to quantitatively determine the atrophy of each brain region. Activities of daily living (ADL) were estimated using the Kurtzke Expanded Disability Status Scale (EDSS). Cognitive function was assessed using the following tests: Mini-Mental State Examination (MMSE), Trail Making Test (TMT), and Paced Auditory Serial Addition Task (PASAT). Z-scores were used to assess significant differences in the neuropsychological test outcomes between the groups.

RESULTS

Six of 19 patients had subcortical and deep WM lesions (non-CL group; diagnosed with relapsing-remitting MS). Thirteen of 19 patients had both subcortical and cortical lesions (CL group; 9-relapsing-remitting MS; 4-primary/secondary progressive MS). There were no significant differences in age, education, and disease duration, but EDSS scores were significantly higher in the CL group compared to the non-CL group. There were no significant differences in gray and white matter volume between the CL and the non-CL groups, but the white matter lesion volume was significantly higher in the CL group compared to the non-CL group. Neuropsychological tests showed significant performance worsening in the CL group as compared to the standard values for healthy individuals in their age group, especially in the TMT data.

CONCLUSIONS

Progressive MS, which was associated with decreased physical functioning, ADL, and cognitive impairment, was found in patients in the CL group.

A new focal model resembling features of cortical pathology of the progressive forms of multiple sclerosis: Influence of innate immunity

Multiple sclerosis (MS) is an inflammatory and demyelinating disease of unknown aetiology that causes neurological disabilities in young adults. MS displays different clinical patterns, including recurrent episodes with remission periods ("relapsing-remitting MS" (RRMS)), which can progress over several years to a secondary progressive form (SPMS). However, 10% of patients display persistent progression at the onset of disease ("primary progressive MS" (PPMS)). Currently, no specific therapeutic agents are available for the progressive forms, mainly because the underlying pathogenic mechanisms are not clear and because no animal models have been specifically developed for these forms. The development of MS animal models is required to clarify the pathological mechanisms and to test novel therapeutic agents. In the present work, we overexpressed interleukin 1 beta (IL-1β) in the cortex to develop an animal model reflecting the main pathological hallmarks of MS. The treated animals presented with neuroinflammation, demyelination, glial activation, and neurodegeneration along with cognitive symptoms and MRI images consistent with MS pathology. We also demonstrated the presence of meningeal inflammation close to cortical lesions, with characteristics similar to those described in MS patients. Systemic pro-inflammatory stimulation caused a flare-up of the cortical lesions and behavioural symptoms, including impairment of working memory and the appearance of anxiety-like symptoms. Our work demonstrated induced cortical lesions, reflecting the main histopathological hallmarks and cognitive impairments characterizing the cortical pathology described in MS patients with progressive forms of the disease.

Relation of serum levels of homocysteine, vitamin B12 and folate to cognitive functions in multiple sclerosis patients

BACKGROUND

Hyperhomocysteinemia, vitamin B12 and folate deficiency have been linked to cognitive dysfunction in multiple sclerosis (MS) patients.

OBJECTIVE

This study aimed to investigate the relation of serum homocysteine (Hcy), vitamin B12 and folate to cognitive functions in MS patients.

SUBJECTS AND METHODS

Forty-five MS patients and twenty matched healthy controls were included. Subjects were submitted to cognitive assessment using a selected psychometric battery and measurement of serum levels of homocysteine, B12 and folic acid.

RESULTS

MS patients showed significant worse performance in cognitive scales compared to controls (P  ≤ 0.05). Serum homocysteine, vitamin B12 and folate showed no significant difference between patients and controls (P  > 0.05). Serum homocysteine was negatively correlated with total score of Addenbrooke's Cognitive Examination (ACE), paced auditory serial addition test and controlled oral word association test scores. Serum vitamin B12 was positively correlated with ACE language, visuospatial and total scores and negatively correlated with trail making B score. Serum folate was significantly positively correlated with ACE language and total scores. Homocysteine was the only significant predictor for cognitive impairment in MS patients.

CONCLUSION

Serum homocysteine may play a role in cognitive dysfunction in MS patients.

Improved Visualization of Cortical Lesions in Multiple Sclerosis Using 7T MP2RAGE

BACKGROUND AND PURPOSE

Cortical lesions are common and often extensive in multiple sclerosis but are difficult to visualize by MRI, leaving important questions about their clinical implications and response to therapy unanswered. Our aim was to determine whether cortical lesions are better visualized using magnetization prepared 2 rapid acquisition gradient echoes (MP2RAGE) than T2*-weighted imaging on 7T MR imaging.

MATERIALS AND METHODS

Brain MR imaging using T1-weighted MP2RAGE at 500-μm isotropic resolution, T2*-weighted gradient-echo, and T2*-weighted segmented echo-planar imaging sequences were collected for 13 patients with MS and 5 age-matched neurologically healthy controls on a 7T research system. One MS case underwent postmortem MR imaging including gradient-echo and MP2RAGE sequences, after which cortical lesions seen on MR imaging were assessed with immunohistochemistry.

RESULTS

MP2RAGE detected 203 cortical lesions (median, 16 lesions/case; interquartile range, 15), compared to 92 with T2*gradient-echo (median, 7; interquartile range, 8; P < .001) and 81 with T2*EPI (median, 7; interquartile range, 5; P < .001). This increase in lesion number detected on MP2RAGE versus T2* was observed for juxtacortical, leukocortical, and intracortical lesions. Forty-three percent of all cortical lesions were identified only on MP2RAGE. White matter lesion volume correlated with total juxtacortical (r = 0.86, P < .001) and leukocortical lesion volume (r = 0.70, P < .01) but not intracortical lesion volume, suggesting that pathophysiology may differ by lesion type. Of 4 suspected lesions seen on postmortem imaging, 3 were found to be true cortical lesions while 1 represented postmortem tissue damage.

CONCLUSIONS

A combination of MP2RAGE and T2*-weighted imaging at 7T improved detection of cortical lesions and should enable longitudinal studies to elucidate their spatiotemporal dynamics and clinical implications.

Postmortem magnetic resonance imaging

This chapter provides a brief overview of studies that combine postmortem magnetic resonance imaging (MRI) and histopathology. We touch upon the logistics of setting up a protocol that limits unwanted postmortem delays and explain how combining postmortem MRI and histopathology can elucidate the histologic substrate of signal changes that appear on MRI. This is demonstrated by exemplary studies in multiple sclerosis, and includes various histopathologic techniques and a wide range of conventional and advanced MRI sequences at various field strengths. We cover topics such as how to visualize white-matter pathology and repair with conventional and advanced MRI sequences, describe the history of visualizing pathology of the gray matter (with newly developed MRI and immunohistopathology techniques), and how advanced methods have aided research in other neurologic diseases. We conclude with several suggestions for future development, such as bridging the gap between postmortem and in vivo research and the importance of collecting non-neurological control tissue.

Neuropsychology of Multiple Sclerosis: Looking Back and Moving Forward

The neuropsychological aspects of multiple sclerosis (MS) have evolved over the past three decades. What was once thought to be a rare occurrence, cognitive dysfunction is now viewed as one of the most disabling symptoms of the disease, with devastating effects on patients' quality of life. This selective review will highlight major innovations and scientific discoveries in the areas of neuropathology, neuroimaging, diagnosis, and treatment that pertain to our understanding of the neuropsychological aspects of MS. Specifically, we focus on the recent discovery that MS produces pathogical lesions of gray matter (GM) that have consequences for cognitive functions. Methods for imaging these GM lesions in MS are discussed along with multimodal imaging studies that integrate structural and functional imaging methods to provide a better understanding of the relationship between cognitive test performance and functional reserve. Innovations in the screening and comprehensive assessment of cognitive disorders are presented along with recent research that examines cognitive dysfunction in pediatric MS. Results of innovative outcome studies in cognitive rehabilitation are discussed. Finally, we highlight trends for potential future innovations over the next decade. (JINS, 2017, 23, 832-842).

Cortical pathology in multiple sclerosis detected by the T1/T2-weighted ratio from routine magnetic resonance imaging

OBJECTIVE

In multiple sclerosis, neuropathological studies have shown widespread changes in the cerebral cortex. In vivo imaging is critical, because the histopathological substrate of most measurements is unknown.

METHODS

Using a novel magnetic resonance imaging analysis technique, based on the ratio of T1- and T2-weighted signal intensities, we studied the cerebral cortex of a large cohort of patients in early stages of multiple sclerosis. A total of 168 patients with clinically isolated syndrome or relapsing-remitting multiple sclerosis (Expanded Disability Status Scale: median = 1, range = 0-3.5) and 80 age- and sex-matched healthy controls were investigated. We also searched for the histopathological substrate of the T1/T2-weighted ratio by combining postmortem imaging and histopathology in 9 multiple sclerosis brain donors.

RESULTS

Patients showed lower T1/T2-weighted ratio values in parietal and occipital areas. The 4 most significant clusters appeared in the medial occipital and posterior cingulate cortex (each left and right). The decrease of the T1/T2-weighted ratio in the posterior cingulate was related to performance in attention. Analysis of the T1/T2-weighted ratio values of postmortem imaging yielded a strong correlation with dendrite density but none of the other parameters including myelin.

INTERPRETATION

The T1/T2-weighted ratio decreases in early stages of multiple sclerosis in a widespread manner, with a preponderance of posterior areas and with a contribution to attentional performance; it seems to reflect dendrite pathology. As the method is broadly available and applicable to available clinical scans, we believe that it is a promising candidate for studying and monitoring cortical pathology or therapeutic effects in multiple sclerosis. Ann Neurol 2017;82:519-529.

HLA-DRB1*04:05 allele is associated with intracortical lesions on three-dimensional double inversion recovery images in Japanese patients with multiple sclerosis

BACKGROUND

Cortical lesions (CLs) frequently observed in Caucasian patients with multiple sclerosis (MS) contribute to disability. However, it remains unclear whether CLs are associated with clinical features and genetic risk factors, such as HLA-DRB1*15:01 and -DRB1*04:05 in Asian MS patients.

OBJECTIVE

To elucidate the frequency of CLs and their association with HLA-DRB1 and DPB1 alleles in Japanese MS patients.

METHODS

Three-dimensional double inversion recovery imaging and clinical information were retrospectively obtained from 92 Japanese MS patients.

RESULTS

CLs of any type, intracortical lesions (ICLs), and leukocortical lesions (LCLs) were detected in 39.1%, 26.1%, and 28.3% of patients, respectively. MS patients with ICLs had a significantly higher frequency of secondary progression and greater Expanded Disability Status Scale (EDSS) scores than those without ICLs. Similar trends were observed with CLs and LCLs. The number of all three lesion types positively correlated with EDSS scores. The frequency and number of ICLs were significantly higher in HLA-DRB1*15:01 carriers than in HLA-DRB1*15:01 non-carriers, but significantly lower in HLA-DRB1*04:05 carriers than in HLA-DRB1*04:05 non-carriers. Multivariate logistic regression analysis revealed a negative association of HLA-DRB1*04:05 with ICLs.

CONCLUSION

ICLs are associated with greater disease severity in Japanese MS patients and are partly suppressed by the HLA-DRB1*04:05 allele.

Role of Oligodendrocyte Dysfunction in Demyelination, Remyelination and Neurodegeneration in Multiple Sclerosis

Oligodendrocytes (OLs) are the myelinating cells of the central nervous system (CNS) during development and throughout adulthood. They result from a complex and well controlled process of activation, proliferation, migration and differentiation of oligodendrocyte progenitor cells (OPCs) from the germinative niches of the CNS. In multiple sclerosis (MS), the complex pathological process produces dysfunction and apoptosis of OLs leading to demyelination and neurodegeneration. This review attempts to describe the patterns of demyelination in MS, the steps involved in oligodendrogenesis and myelination in healthy CNS, the different pathways leading to OLs and myelin loss in MS, as well as principles involved in restoration of myelin sheaths. Environmental factors and their impact on OLs and pathological mechanisms of MS are also discussed. Finally, we will present evidence about the potential therapeutic targets in re-myelination processes that can be accessed in order to develop regenerative therapies for MS.

Delineation of cortical pathology in multiple sclerosis using multi-surface magnetization transfer ratio imaging

The purpose of our study was to evaluate the utility of measurements of cortical surface magnetization transfer ratio (csMTR) on the inner, mid and outer cortical boundaries as clinically accessible biomarkers of cortical gray matter pathology in multiple sclerosis (MS). Twenty-five MS patients and 12 matched controls were recruited from the MS Clinic of the Montreal Neurological Institute. Anatomical and magnetization transfer ratio (MTR) images were acquired using 3 Tesla MRI at baseline and two-year time-points. MTR maps were smoothed along meshes representing the inner, mid and outer neocortical boundaries. To evaluate csMTR reductions suggestive of sub-pial demyelination in MS patients, a mixed model analysis was carried out at both the individual vertex level and in anatomically parcellated brain regions. Our results demonstrate that focal areas of csMTR reduction are most prevalent along the outer cortical surface in the superior temporal and posterior cingulate cortices, as well as in the cuneus and precentral gyrus. Additionally, age regression analysis identified that reductions of csMTR in MS patients increase with age but appear to hit a plateau in the outer caudal anterior cingulate, as well as in the precentral and postcentral cortex. After correction for the naturally occurring gradient in cortical MTR, the difference in csMTR between the inner and outer cortex in focal areas in the brains of MS patients correlated with clinical disability. Overall, our findings support multi-surface analysis of csMTR as a sensitive marker of cortical sub-pial abnormality indicative of demyelination in MS patients.

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Novel cortical MTR analysis identifies areas of sub-pial abnormality in MS patients.

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A greater area of sub-pial abnormality in MS exists on the outer cortical layer.

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Cortical regions most affected were involved in executive function and processing speed.

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Normalized differences between outer and inner cortex MTR correlate with EDSS in MS.

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This technique can be applied for clinical trials at the MRI field strength of 3 T.

Diffusion Tensor Imaging-Defined Sulcal Enlargement Is Related to Cognitive Impairment in Multiple Sclerosis

BACKGROUND AND PURPOSE

Cerebrospinal fluid (CSF) in the brain can be compartmentalized into two main divisions: ventricular CSF and subarachnoid space (sulcal CSF). Changes in CSF volumetry are seen in many neurological conditions including multiple sclerosis (MS) and found to correlate with clinical outcomes. We aimed to test the relation between the volumetry of sulcal and ventricular CSF and cognitive impairment (CI) based on the minimal assessment of cognitive function in MS (MACFIMS) in patients with MS.

MATERIAL AND METHODS

Forty-six patients with MS underwent the MACFIMS battery and classified as nonimpaired (MSNI) (n = 10) and cognitively impaired (MSCI) (n = 30) and borderline (MSBD) MS patients (n = 6). Volumes of sulcal and ventricular CSF along with global gray and white matter volumes and cortical thickness were obtained by diffusion tensor imaging (DTI) and T1-weighted (T1w)-based segmentation. These measures were statistically analyzed for associations with CI after adjusting for the age, education in years, lesion load, and disease duration.

RESULTS

Sulcal CSF showed the strongest correlation with CI (r = .51, P = .001) in our cohort, whereas ventricular CSF (P = .28, P = .19) along with cortical thickness and gray matter volume failed to show a significant correlation. Group analyses unadjusted for multiple comparisons showed significant difference in volumes of sulcal CSF and ventricular CSF between MSNI and MSCI groups (P < .05).

CONCLUSION

Sulcal CSF correlates with CI in patients with MS, possibly explained by cortical atrophy. DTI/T1w-based sulcal CSF segmentation method might be used as an indirect and simple neuroimaging marker to monitor CI in MS patients.

The association between intra- and juxta-cortical pathology and cognitive impairment in multiple sclerosis by quantitative T2* mapping at 7 T MRI

Using quantitative T₂* at 7 Tesla (T) magnetic resonance imaging, we investigated whether impairment in selective cognitive functions in multiple sclerosis (MS) can be explained by pathology in specific areas and/or layers of the cortex.

Thirty-one MS patients underwent neuropsychological evaluation, acquisition of 7 T multi-echo T₂* gradient-echo sequences, and 3 T anatomical images for cortical surfaces reconstruction. Seventeen age-matched healthy subjects served as controls.

Cortical T₂* maps were sampled at various depths throughout the cortex and juxtacortex. Relation between T₂*, neuropsychological scores and a cognitive index (CI), calculated from a principal component analysis on the whole battery, was tested by a general linear model.

Cognitive impairment correlated with T₂* increase, independently from white matter lesions and cortical thickness, in cortical areas highly relevant for cognition belonging to the default-mode network (p < 0.05 corrected). Dysfunction in different cognitive functions correlated with longer T₂* in selective cortical regions, most of which showed longer T₂* relative to controls. For most tests, this association was strongest in deeper cortical layers. Executive dysfunction, however, was mainly related with pathology in juxtameningeal cortex. T₂* explained up to 20% of the variance of the CI, independently of conventional imaging metrics (adjusted-R²: 52–67%, p < 5.10^− 4).

Location of pathology across the cortical width and mantle showed selective correlation with impairment in differing cognitive domains. These findings may guide studies at lower field strength designed to develop surrogate markers of cognitive impairment in MS.

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Cognitive deficit in multiple sclerosis is associated with cortical T₂* increase.

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Location of clusters of correlation varies upon affected cognitive domains.

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Global cognitive deficit was associated with T₂* increase in deepest cortical layers.

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Executive dysfunction was associated with T₂* increase in outer cortical layers.

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Regional T₂* explained up to 20% of the variance of cognitive performance in MS.