Abstract:
OBJECTIVES: Investigating differential vulnerability of thalamic nuclei in multiple sclerosis (MS). METHODS: In a secondary analysis of prospectively collected datasets, we pooled 136 patients with MS or clinically isolated syndrome and 71 healthy controls all scanned with conventional 3D-T1 and white-matter-nulled magnetization-prepared rapid gradient echo (WMn-MPRAGE) and tested for cognitive performance. T1-based thalamic segmentation was compared with the reference WMn-MPRAGE method. Volumes of thalamic nuclei were compared according to clinical phenotypes and cognitive profile. RESULTS: T1- and WMn-MPRAGE provided comparable segmentations (0.84 +/- 0.13 < volume-similarity-index < 0.95 +/- 0.03). Medial and posterior thalamic groups were significantly more affected than anterior and lateral groups. Cognitive impairment related to volume loss of the anterior group. CONCLUSION: Thalamic nuclei closest to the third ventricle are more affected, with cognitive consequences.

Abstract:
BACKGROUND: Cognitive impairment occurs in the earliest stages of multiple sclerosis (MS) together with altered functional connectivity (FC). OBJECTIVE: The aim of this study was to investigate the evolution of dynamic FC states in early MS and their role in shaping cognitive decline. METHODS: Overall, 32 patients were enrolled after their first neurological episode suggestive of MS and underwent cognitive evaluation and resting-state functional MRI (fMRI) over 5 years. In addition, 28 healthy controls were included at baseline. RESULTS: Cognitive performance was stable during the first year and declined after 5 years.At baseline, the number of transitions between states was lower in MS compared to controls (p = 0.01). Over time, frequency of high FC states decreased in patients (p = 0.047) and increased in state with low FC (p = 0.035). Cognitive performance at Year 5 was best predicted by the mean connectivity of high FC state at Year 1. CONCLUSION: Patients with early MS showed reduced functional network dynamics at baseline. Longitudinal changes showed longer time spent in a state of low FC but less time spent and more connectivity disturbance in more integrative states with high within- and between-network FC. Disturbed FC within this more integrative state was predictive of future cognitive decline.

Abstract:
While memory impairment in multiple sclerosis (MS) is known to be associated with hippocampal alterations, whether hippocampal networks could dynamically reorganize as a compensation mechanism is still a matter of debate. In this context, our aim was to identify the patterns of structural and functional connectivity between the hippocampus and the rest of the brain and their possible relevance to memory performances in early MS. Thirty-two patients with a first episode suggestive of MS together with 10 matched healthy controls were prospectively explored at baseline, 1 and 5 years follow up. They were scanned with MRI and underwent a neuropsychological battery of tests that included the Selective Reminding Test and the Brief Visual Memory Test Revised to assess verbal and visuo-spatial memory, respectively. Hippocampal volume was computed together with four graph theory metrics to study the structural and functional connectivity of both hippocampi with the rest of the brain. Associations between network parameters and memory performances were assessed using linear mixed-effects (LME) models. Considering cognitive abilities, verbal memory performances of patients decreased over time while visuo-spatial memory performances were maintained. In parallel, hippocampal volumes decreased significantly while structural and functional connectivity metrics were modified, with an increase in hippocampal connections over time. More precisely, these modifications were indicating a reinforcement of hippocampal short-distance connections. LME models revealed that the drop in verbal memory performances was associated with hippocampal volume loss, while the preservation of visuo-spatial memory performances was linked to decreased hippocampal functional shortest path length. In conclusion, we demonstrated a differential impairment in memory performances in the early stages of MS and an important interplay between hippocampal-related structural and functional networks and those performances. As the structural damage increases, functional reorganization seems to be able to maintain visuo-spatial memory performances with strengthened short-distance connections.

Abstract:
Background and Objectives: Young adults represent an increasingly large proportion of healthy volunteers in brain imaging research, but descriptions of incidental findings (IFs) in this age group are scarce. We aimed to assess the prevalence and severity of IFs on brain MRIs of healthy young research participants aged 18-35 years, and to describe the protocol implemented to handle them. Methods: The study population comprised 1,867 participants aged 22.1 +/- 2.3 years (72% women) from MRi-Share, the cross-sectional brain MRI substudy of the i-Share student cohort. IFs were flagged during the MRI quality control. We estimated the proportion of participants with IFs [any, requiring medical referral, potentially serious (PSIFs) as defined in the UK biobank]: overall, by type and severity of the final diagnosis, as well as the number of IFs. Results: 78/1,867 participants had at least one IF [4.2%, 95% Confidence Interval (CI) 3.4-5.2%]. IFs requiring medical referral (n = 38) were observed in 36/1,867 participants (1.9%, 1.4-2.7%), and represented 47.5% of the 80 IFs initially flagged. Referred IFs were retrospectively classified as PSIFs in 25/1,867 participants (1.3%, 0.9-2.0%), accounting for 68.4% of anomalies referred (26/38). The most common final diagnosis was cysts or ventricular abnormalities in all participants (9/1,867; 0.5%, 0.2-0.9%) and in those with referred IFs (9/36; 25.0%, 13.6-41.3%), while it was multiple sclerosis or radiologically isolated syndrome in participants with PSIFs (5/19; 26.3%, 11.5-49.1%) who represented 0.1% (0.0-0.4%) and 0.2% (0.03-0.5%) of all participants, respectively. Final diagnoses were considered serious in 11/1,867 participants (0.6%, 0.3-1.1%). Among participants with referred IFs, 13.9% (5/36) required active intervention, while 50.0% (18/36) were put on clinical surveillance. Conclusions: In a large brain imaging study of young healthy adults participating in research we observed a non-negligible frequency of IFs. The etiological pattern differed from what has been described in older adults.

Abstract:
BACKGROUND: The Minimal Assessment of Cognitive Function in Multiple sclerosis (MACFIMS) is an internationally recognised battery of neuropsychological tests for patients with multiple sclerosis (MS). OBJECTIVES: To establish regression-based norms for the MACFIMS in French-speaking healthy subjects (HS) and validate its use in persons with multiple sclerosis (PwMS). METHODS: 136 PwMS, including 43 with relapsing-remitting MS, 46 with secondary progressive MS and 45 with primary progressive MS, as well as 276 HS were enrolled. Regression-based norms and validity were established for the seven tests of the MACIMS: the Symbol Digit Modalities Test (SDMT), the Paced Auditory Serial Addition Test (PASAT), the French learning test (FLT) a French-adapted memory test (or the California Verbal Learning Test (CVLT) at re-testing), the Judgment of Line Orientation Test (JLO), the 'epreuve de classement de cartes de Champagne' (ECCC), a French adaptation of the DKEF-sorting test, the Brief Visuospatial Memory Test (BVMT-R) and the Controlled Oral Word Association Test (COWAT). RESULTS: Regression-based norms of MACFIMS tests were established in the HS population. The MACFIMS battery was able to identify cognitive impairment (CI) (at least two abnormal tests in different domains) in 32.7% of PwMS. The domains with more frequent impairment were (in descending order): learning followed by IPS, delayed memory, verbal fluency and working memory. CONCLUSION: This study established the regression-based norms for French subjects of the French adaptation of the MACFIMS and its validity in PwMS.

Abstract:
BACKGROUND: The relationship between structural and functional deficits in multiple sclerosis (MS) is unclear. OBJECTIVE: This study explored structure-function relationships during the 5 years following a clinically isolated syndrome and their role in cognitive performance. METHODS: Thirty-two patients were enrolled after their first neurological episode suggestive of MS and followed for 5 years, along with 10 matched healthy controls. We assessed structural (using diffusion tensor imaging) and functional (using resting-state functional magnetic resonance imaging (fMRI)) brain network metrics, clinical and cognitive scores at each follow-up visit. Structural-functional coupling, calculated as the correlation coefficient between strengths of structural and functional networks, was used to assess structure-function relationships. RESULTS: Structural clustering coefficient was significantly increased after 5 years, whereas characteristic path length decreased. Structural connections decreased after 1 year and increased after 5 years. Functional connections and related path lengths were decreased after 5 years. Structural-functional coupling had increased significantly after 5 years. This structural-functional coupling was associated with cognitive and clinical evolution, with stronger coupling associated with a decline in both domains. CONCLUSION: Our findings provide novel biological evidence that MS leads to a more constrained anatomical-dependant functional connectivity. The collapse of this network seems to lead to both cognitive worsening and clinical disability.

Abstract:
PURPOSE: The purpose of this study was to create an algorithm that combines multiple machine-learning techniques to predict the expanded disability status scale (EDSS) score of patients with multiple sclerosis at two years solely based on age, sex and fluid attenuated inversion recovery (FLAIR) MRI data. MATERIALS AND METHODS: Our algorithm combined several complementary predictors: a pure deep learning predictor based on a convolutional neural network (CNN) that learns from the images, as well as classical machine-learning predictors based on random forest regressors and manifold learning trained using the location of lesion load with respect to white matter tracts. The aggregation of the predictors was done through a weighted average taking into account prediction errors for different EDSS ranges. The training dataset consisted of 971 multiple sclerosis patients from the 'Observatoire francais de la sclerose en plaques' (OFSEP) cohort with initial FLAIR MRI and corresponding EDSS score at two years. A test dataset (475 subjects) was provided without an EDSS score. Ten percent of the training dataset was used for validation. RESULTS: Our algorithm predicted EDSS score in patients with multiple sclerosis and achieved a MSE=2.2 with the validation dataset and a MSE=3 (mean EDSS error=1.7) with the test dataset. CONCLUSION: Our method predicts two-year clinical disability in patients with multiple sclerosis with a mean EDSS score error of 1.7, using FLAIR sequence and basic patient demographics. This supports the use of our model to predict EDSS score progression. These promising results should be further validated on an external validation cohort.

Abstract:
BACKGROUND: There are few head-to-head studies to compare highly active treatments in multiple sclerosis (MS). OBJECTIVE: The aim of this study was to compare the effectiveness between natalizumab (NTZ) and fingolimod (FTY) in active relapsing-remitting MS. METHOD: Best Escalation STrategy in Multiple Sclerosis (BEST-MS) is a multicentric, prospective study with a 12-month follow-up including patients with active MS. Treatment choice was at the discretion of physician. Clinical and magnetic resonance imaging (MRI) data were collected at baseline and at 12 months. The primary outcome was the proportion of patients reaching no evidence of disease activity (NEDA) at 12 months. Secondary outcomes included annualized relapse rate and MRI activity. RESULTS: A total of 223 patients were included (NTZ: 109 and FTY: 114). Treatment groups were well balanced at baseline. Proportion of NEDA patients was 47.8% in NTZ group versus 30.4% in FTY group (p = 0.015). This superiority was driven by annualized relapse rate and MRI activity. In the multivariate analysis, treatment group was the only factor associated with NEDA at 12 months with a lower probability in FTY group (odds ratio (OR) = 0.49, p = 0.029). CONCLUSION: BEST-MS is a prospective study that compared head-to-head the effectiveness of NTZ and FTY in active relapsing-remitting MS. Our results suggest a superiority of NTZ over FTY.

Abstract:
BACKGROUND: Specific cognitive rehabilitation (SCR) has been suggested for multiple sclerosis (MS). A randomized controlled trial (RCT) evaluating the therapeutic effects of SCR is necessary. OBJECTIVE: To demonstrate the superiority of a SCR program (REACTIV) over nonspecific intervention (NSI) for neuropsychological (NP) assessment, virtual reality (VR) cognitive testing and daily cognitive functioning. METHODS: A single-blind RCT compared SCR and NSI in patients with MS with cognitive complaint. Both programs included 50 individual sessions, 3 times a week for 17 weeks in a real-world setting. The primary end-point was NP assessment. Secondary end-points included semiecological VR tasks (Urban Daily Cog(R)) and daily cognitive functioning assessment. Maintenance of the effects at 8 months was studied. RESULTS: Of the 35 patients, 18 completed the SCR, and 17 completed the NSI. Several NP and semiecological scores improved significantly more after SCR than after NSI. More NP scores improved significantly after SCR than after NSI. SCR improved daily cognitive functioning. Most improvements were maintained at 8 months. CONCLUSION: SCR performed in a real-world setting is superior to NSI for improving performance in specific cognitive domains and information processing speed, and for improving cognitive functioning, as evaluated by ecological tools close to daily life and a daily cognitive functioning questionnaire.

Abstract:
BACKGROUND: Cognitive impairment is important to consider in the assessment of multiple sclerosis (MS) patients. A short battery of cognitive assessment, the Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS), has been developed to address the need for rapid assessment by combining 3 tests assessing the main cognitive spheres reached in MS. OBJECTIVES: To establish regression-based norms of the BICAMS in French speaking healthy subjects (HS) and validate its use in persons with multiple sclerosis (PwMS). METHODS: In all, 123 PwMS including 40 with relapsing-remitting MS, 41 patients with secondary progressive MS and 42 with primary progressive MS and 276 HS were evaluated by the BICAMS including 3 tests, the Symbol Digit Modalities Test (SDMT), the French Verbal learning test (FVLT) a French-adapted memory test, (or the California Verbal Learning Test (CVLT) at retesting) and the Brief Visuo-Spatial Memory Test (BVMT-R). The standards for these tests were established in the healthy population using a multiple regression technique. Validity in MS was measured. RESULTS: Regression-based norms of BICAMS tests have been established in the HS population. 50.4% of PwMS have impairment for at least one BICAMS test (-1.5SD on the Z-score). The most common pathological test was the FVLT altered in 36.6% of patients, followed by the SDMT and the BVMT-R. The re-test reliability was good for the various BICAMS tests, 0.891 for SDMT, 0.781 for FVLT/CVLT and 0.669 for BVMT-R. CONCLUSION: This study establishes the validity of the BICAMS as a short and easy to apply battery for a brief assessment of the speed of information processing and episodic memory in MS.