Unexpected Low Rate of Amyloid-ß Pathology in Multiple Sclerosis Patients.

The life expectancy of people with multiple sclerosis (MS) has increased, yet we have noted that development of a typical Alzheimer disease dementia syndrome is uncommon. We hypothesized that Alzheimer disease pathology is uncommon in MS patients. In 100 MS patients, the rate of amyloid-ß plasma biomarker positivity was approximately half the rate in 300 non-MS controls matched on age, sex, apolipoprotein E proteotype, and cognitive status. Interestingly, most MS patients who did have amyloid-ß pathology had features atypical for MS at diagnosis. These results support that MS is associated with reduced Alzheimer disease risk, and suggest new avenues of research. ANN NEUROL 2024.

Dimethyl Fumarate Delays Multiple Sclerosis in Radiologically Isolated Syndrome.

OBJECTIVE: The radiologically isolated syndrome (RIS) represents the earliest detectable pre-clinical phase of multiple sclerosis (MS). This study evaluated the impact of therapeutic intervention in preventing first symptom manifestation at this stage in the disease spectrum. METHODS: We conducted a multi-center, randomized, double-blinded, placebo-controlled study involving people with RIS. Individuals without clinical symptoms typical of MS but with incidental brain MRI anomalies consistent with central nervous system (CNS) demyelination were included. Within 12 MS centers in the United States, participants were randomly assigned 1:1 to oral dimethyl fumarate (DMF) 240 mg twice daily or placebo. The primary endpoint was the time to onset of clinical symptoms attributable to a CNS demyelinating event within a follow-up period of 96 weeks. An intention-to-treat analysis was applied to all participating individuals in the primary and safety investigations. The study is registered at ClinicalTrials.gov, NCT02739542 (ARISE). RESULTS: Participants from 12 centers were recruited from March 9, 2016, to October 31, 2019, with 44 people randomized to dimethyl fumarate and 43 to placebo. Following DMF treatment, the risk of a first clinical demyelinating event during the 96-week study period was highly reduced in the unadjusted Cox proportional-hazards regression model (hazard ratio [HR] = 0.18, 95% confidence interval [CI] = 0.05-0.63, p = 0.007). More moderate adverse reactions were present in the DMF (34 [32%]) than placebo groups (19 [21%]) but severe events were similar (DMF, 3 [5%]; placebo, 4 [9%]). INTERPRETATION: This is the first randomized clinical trial demonstrating the benefit of a disease-modifying therapy in preventing a first acute clinical event in people with RIS. ANN NEUROL 2023;93:604-614.

Structural MRI measures are associated with fatigue severity and persistence in a large, real-world cohort of people with multiple sclerosis.

BACKGROUND: Results of research on radiological hallmarks of multiple sclerosis (MS) fatigue have been conflicting. OBJECTIVE: To investigate the associations of lesion and brain compartment volumes with fatigue severity and persistence in people with multiple sclerosis (PwMS). METHODS: The Multiple Sclerosis Partners Advancing Technology and Health Solutions (MS PATHS) network collects standardized data during routine care of PwMS from 10 healthcare institutions. Magnetic resonance imaging (MRI) predictors included baseline brain parenchymal (BPF) and gray matter fractions (GMF) and T2 lesion volume (T2LV). The Quality of Life in Neurological Disorders (Neuro-QOL) fatigue subscore was analyzed linearly and categorically using T-score cutpoints, with a period of elevated symptoms defined as T-score ⩾ mean + 0.5 SD over follow-up. RESULTS: At baseline, of 4012 participants (average age: 45.6 ± 11.8 years; 73% female; 31% progressive MS), 2058 (51%) had no fatigue, 629 (16%) had mild fatigue, and 1325 (33%) had moderate-to-severe fatigue. One SD greater baseline BPF and GMF were associated with 0.83 (p < 0.001) and 0.38 (p = 0.02) lower values in the baseline Neuro-QOL fatigue T-score. A 1 SD lower log of total T2LV was associated with a 0.49 (p < 0.001) lower baseline fatigue T-score. Higher BPF and lower T2LV at baseline were associated with lower odds of subsequent periods of elevated fatigue. CONCLUSION: Baseline lesion burden and lower generalized whole-brain volumes were associated with MS fatigue in cross-sectional and longitudinal analyses in a large, real-world cohort of PwMS.

Concurrent administration of serotonergic antidepressants and ozanimod in participants with relapsing multiple sclerosis from the open-label extension DAYBREAK trial.

BACKGROUND: Monoamine oxidase (MAO) inhibitors can interact with selective serotonin reuptake inhibitors (SSRIs)/serotonin-norepinephrine reuptake inhibitors (SNRIs). There is clinical interest surrounding use of ozanimod with SSRIs/SNRIs because the major metabolites of ozanimod are weak inhibitors of MAO-B in vitro. OBJECTIVE: To evaluate the incidence of treatment-emergent adverse events (TEAEs) potentially related to serotonin accumulation (SA) during concomitant ozanimod and SSRI/SNRI use by performing analyses of data from an open-label, oral ozanimod 0.92 mg trial (DAYBREAK; NCT02576717). METHODS: SA narrow (serotonin syndrome, neuroleptic malignant syndrome, and hyperthermia malignant) and broad (terms potentially associated with SA) MedDRA v24.0 searches were performed using TEAE data from participants with relapsing multiple sclerosis who entered DAYBREAK from phase 3 studies (cutoff February 1, 2022). Incidences of TEAEs matching terms from each search were stratified by SSRI/SNRI use. RESULTS: Of 2257 DAYBREAK participants, 274 (12.1%) used an SSRI/SNRI. No participants had TEAEs matching the SA narrow search terms. There was no significant difference in the percentage of participants with ⩾1 TEAE matching the SA broad search for those on versus off SSRIs/SNRIs (on: 12.4%, n = 34/274; off: 15.6%, n = 310/1982, nominal p = 0.1630). CONCLUSION: MedDRA searches showed no increase in TEAEs potentially associated with SA with concomitant SSRI/SNRI and ozanimod use.

Diroximel fumarate in patients with relapsing-remitting multiple sclerosis: Final safety and efficacy results from the phase 3 EVOLVE-MS-1 study.

BACKGROUND: Diroximel fumarate (DRF) is approved for adults with relapsing-remitting multiple sclerosis (RRMS) in Europe and for relapsing forms of MS in the United States. DRF and dimethyl fumarate (DMF) yield bioequivalent exposure of the active metabolite monomethyl fumarate. Prior studies indicated fewer gastrointestinal (GI)-related adverse events (AEs) with DRF compared with DMF. OBJECTIVE: To report final outcomes from EVOLVE-MS-1. METHODS: EVOLVE-MS-1 was an open-label, 96-week, phase 3 study assessing DRF safety, tolerability, and efficacy in patients with RRMS. The primary endpoint was safety and tolerability; efficacy endpoints were exploratory. RESULTS: Overall, 75.7% (800/1057) of patients completed the study; median exposure was 1.8 (range: 0.0-2.0) years. AEs occurred in 938 (88.7%) patients, mostly of mild (28.9%) or moderate (50.3%) severity. DRF was discontinued due to AEs in 85 (8.0%) patients, with < 2% discontinuing due to GI or flushing/flushing-related AEs. At Week 96, mean number of gadolinium-enhancing lesions was significantly reduced from baseline (72.7%; p < 0.0001); adjusted annualized relapse rate was 0.13 (95% confidence interval: 0.11-0.15). CONCLUSION: DRF was generally well tolerated over 2 years, with few discontinuations due to AEs; radiological measures indicated decreased disease activity from baseline. These outcomes support DRF as a treatment option in patients with RRMS.

Central vein sign and other radiographic features distinguishing myelin oligodendrocyte glycoprotein antibody disease from multiple sclerosis and aquaporin-4 antibody-positive neuromyelitis optica.

BACKGROUND: Myelin oligodendrocyte glycoprotein antibody disease (MOGAD) can radiographically mimic multiple sclerosis (MS) and aquaporin-4 (AQP4) antibody-positive neuromyelitis optica spectrum disorder (NMOSD). Central vein sign (CVS) prevalence has not yet been well-established in MOGAD. OBJECTIVE: Characterize the magnetic resonance imaging (MRI) appearance and CVS prevalence of MOGAD patients in comparison to matched cohorts of MS and AQP4+ NMOSD. METHODS: Clinical MRIs from 26 MOGAD patients were compared to matched cohorts of MS and AQP4+ NMOSD. Brain MRIs were assessed for involvement within predefined regions of interest. CVS was assessed by overlaying fluid-attenuated inversion recovery (FLAIR) and susceptibility-weighted sequences. Topographic analyses were performed on spinal cord and orbital MRIs when available. RESULTS: MOGAD patients had fewer brain lesions and average CVS+ rate of 12.1%, compared to 44.4% in MS patients (p = 0.0008). MOGAD spinal cord and optic nerve involvement was lengthier than MS (5.8 vs 1.0 vertebral segments, p = 0.020; 3.0 vs 0.5 cm, p < 0.0001). MOGAD patients tended to have bilateral/anterior optic nerve pathology with perineural contrast enhancement, contrasting with posterior optic nerve involvement in NMOSD. CONCLUSION: CVS+ rate and longer segments of involvement in the spinal cord and optic nerve can differentiate MOGAD from MS, but do not discriminate as well between MOGAD and AQP4+ NMOSD.

Multiple sclerosis diagnosis: Knowledge gaps and opportunities for educational intervention in neurologists in the United States.

BACKGROUND: Few studies have addressed the results of educational efforts concerning proper use of McDonald criteria (MC) revisions outside multiple sclerosis (MS) subspecialty centers. Neurology residents and MS subspecialist neurologists demonstrated knowledge gaps for core elements of the MC in a recent prior study. OBJECTIVE: To assess comprehension and application of MC core elements by non-MS specialist neurologists in the United States who routinely diagnose MS. METHODS: Through a cross-sectional study design, a previously developed survey instrument was distributed online. RESULTS: A total of 222 neurologists completed the study survey. Syndromes atypical for MS were frequently incorrectly considered "typical" MS presentations. Fourteen percent correctly identified definitions of both "periventricular" and "juxtacortical" lesions and 2% correctly applied these terms to 9/9 images. Twenty-four percent correctly identified all four central nervous system (CNS) regions for satisfaction of magnetic resonance imaging (MRI) dissemination in space. In two presented cases, 61% and 71% correctly identified dissemination in time (DIT) was not fulfilled, and 85% and 86% subsequently accepted nonspecific historical symptoms without objective evidence for DIT fulfillment. CONCLUSION: The high rate of knowledge deficiencies and application errors of core elements of the MC demonstrated by participants in this study raise pressing questions concerning adequacy of dissemination and educational efforts upon publication of revisions to MC.

Phase 2 Trial of Ibudilast in Progressive Multiple Sclerosis.

BACKGROUND: There are limited treatments for progressive multiple sclerosis. Ibudilast inhibits several cyclic nucleotide phosphodiesterases, macrophage migration inhibitory factor, and toll-like receptor 4 and can cross the blood-brain barrier, with potential salutary effects in progressive multiple sclerosis. METHODS: We enrolled patients with primary or secondary progressive multiple sclerosis in a phase 2 randomized trial of oral ibudilast (≤100 mg daily) or placebo for 96 weeks. The primary efficacy end point was the rate of brain atrophy, as measured by the brain parenchymal fraction (brain size relative to the volume of the outer surface contour of the brain). Major secondary end points included the change in the pyramidal tracts on diffusion tensor imaging, the magnetization transfer ratio in normal-appearing brain tissue, the thickness of the retinal nerve-fiber layer, and cortical atrophy, all measures of tissue damage in multiple sclerosis. RESULTS: Of 255 patients who underwent randomization, 129 were assigned to ibudilast and 126 to placebo. A total of 53% of the patients in the ibudilast group and 52% of those in the placebo group had primary progressive disease; the others had secondary progressive disease. The rate of change in the brain parenchymal fraction was -0.0010 per year with ibudilast and -0.0019 per year with placebo (difference, 0.0009; 95% confidence interval, 0.00004 to 0.0017; P=0.04), which represents approximately 2.5 ml less brain-tissue loss with ibudilast over a period of 96 weeks. Adverse events with ibudilast included gastrointestinal symptoms, headache, and depression. CONCLUSIONS: In a phase 2 trial involving patients with progressive multiple sclerosis, ibudilast was associated with slower progression of brain atrophy than placebo but was associated with higher rates of gastrointestinal side effects, headache, and depression. (Funded by the National Institute of Neurological Disorders and Stroke and others; NN102/SPRINT-MS ClinicalTrials.gov number, NCT01982942 .).

Challenges in multiple sclerosis diagnosis: Misunderstanding and misapplication of the McDonald criteria.

OBJECTIVE: To assess comprehension and application of the McDonald criteria. BACKGROUND: Studies suggest that knowledge gaps for specific core elements of the McDonald criteria may contribute to multiple sclerosis (MS) misdiagnosis. METHODS: Neurology residents (NR) and multiple sclerosis specialists (MSS) in North America completed a web-based survey. RESULTS: A total of 160 participants were included: 72 NR and 88 MSS. Syndromes incorrectly identified as typical of MS included: complete transverse myelopathy (35% NR and 15% MSS), intractable vomiting/nausea/hiccoughs (20% NR and 5% MSS), and bilateral optic neuritis/unilateral optic neuritis with poor visual recovery (17% NR and 10% MSS). Periventricular magnetic resonance imaging (MRI) lesions were correctly identified by 39% NR and 52% MSS, and juxtacortical lesions were correctly identified by 28% NR and 53% MSS. The correct definition of "periventricular" was chosen by 38% NR and 61% MSS, and that of "juxtacortical" was chosen by 19% NR and 54% MSS. Regions incorrectly identified for MRI dissemination in space fulfillment included the optic nerve (31% NR and 26% MSS) and the subcortical white matter (11% NR and 18% MSS). The majority of participants assessed previous non-specific neurological symptoms without objective evidence of a central nervous system (CNS) lesion as sufficient for clinical dissemination in time. CONCLUSION: The McDonald criteria are often misunderstood and misapplied. Concerted educational efforts may prevent MS misdiagnosis.

Neurofilament light chain in a phase 2 clinical trial of ibudilast in progressive multiple sclerosis.

BACKGROUND: Sensitive and specific biomarkers for use in progressive multiple sclerosis (MS) have not been established. We investigate neurofilament light (NfL) as a treatment response biomarker in progressive MS. OBJECTIVE: To evaluate whether ibudilast 100 mg/day alters serum and cerebrospinal fluid (CSF) levels of NfL in progressive MS. METHODS: In a protocol-defined exploratory analysis from a 2-year, phase 2 clinical trial of ibudilast in progressive MS (NCT01982942), serum samples were collected from 239 subjects and a subset contributed CSF and assayed using single-molecule assay (SIMOA) immunoassay. A mixed model for repeated measurements yielded log(NfL) as the response variable. RESULTS: The geometric mean baseline serum NfL was 31.9 and 28.8 pg/mL in placebo and ibudilast groups, respectively. The geometric mean baseline CSF NfL was 1150.8 and 1290.3 pg/mL in placebo and ibudilast groups, respectively. Serum and CSF NfL correlations were r = 0.52 and r = 0.78 at weeks 48 and 96, respectively. Over 96 weeks, there was no between-group difference in NfL in either serum (p = 0.76) or CSF (p = 0.46). After controlling for factors that may affect NfL, no effect of ibudilast on NfL in either serum or CSF was observed. CONCLUSION: Ibudilast treatment was not associated with a change in either serum or CSF NfL.

Optical coherence tomography outcomes from SPRINT-MS, a multicenter, randomized, double-blind trial of ibudilast in progressive multiple sclerosis.

BACKGROUND: The SPRINT-MS trial demonstrated benefit of ibudilast on brain atrophy over 96 weeks in progressive multiple sclerosis (MS). Optical coherence tomography (OCT) was performed in all trial participants. OBJECTIVE: Report the OCT results of the SPRINT-MS trial. METHODS: OCT was obtained at baseline and every 6 months using spectral domain OCT and analyzed by an OCT reading center. Change in each OCT outcome measure by treatment group was estimated using linear mixed models. RESULTS: Change in pRNFL thickness was +0.0424 uM/year (95% confidence interval (CI): -0.3091 to 0.3939) for ibudilast versus -0.2630 uM (95% CI: -0.5973 to 0.0714) for placebo (n = 244, p = 0.22). Macular volume change was -0.00503 mm3/year (-0.02693 to 0.01688) with ibudilast versus -0.03659 mm3/year (-0.05824 to -0.01494) for placebo in the Spectralis cohort (n = 61, p = 0.044). For the Cirrus cohort, macular volume change was -0.00040 mm3/year (-0.02167, 0.020866) with ibudilast compared to -0.02083 mm3/year (-0.04134 to -0.00033) for placebo (n = 183, p = 0.1734). Ganglion cell-inner plexiform layer thickness change, available from Cirrus, was -0.4893 uM/year (-0.9132, -0.0654) with ibudilast versus -0.9587 uM/year (-1.3677, -0.5498) with placebo (n = 183, p = 0.12). CONCLUSION: Retinal thinning in MS may be attenuated by ibudilast. Sample size estimates suggest OCT can be a viable outcome measure in progressive MS trials if a therapy has a large treatment effect. TRIAL REGISTRATION: NN102/SPRINT-MS ClinicalTrials.gov number, NCT01982942.

Diroximel fumarate (DRF) in patients with relapsing-remitting multiple sclerosis: Interim safety and efficacy results from the phase 3 EVOLVE-MS-1 study.

BACKGROUND: Diroximel fumarate (DRF) is a novel oral fumarate for patients with relapsing-remitting multiple sclerosis (RRMS). DRF and the approved drug dimethyl fumarate yield bioequivalent exposure to the active metabolite monomethyl fumarate; thus, efficacy/safety profiles are expected to be similar. However, DRF's distinct chemical structure may result in a differentiated gastrointestinal (GI) tolerability profile. OBJECTIVE: To report interim safety/efficacy findings from patients in the ongoing EVOLVE-MS-1 study. METHODS: EVOLVE-MS-1 is an ongoing, open-label, 96-week, phase 3 study assessing DRF safety, tolerability, and efficacy in RRMS patients. Primary endpoint is safety and tolerability; efficacy endpoints are exploratory. RESULTS: As of March 2018, 696 patients were enrolled; median exposure was 59.9 (range: 0.1-98.9) weeks. Adverse events (AEs) occurred in 84.6% (589/696) of patients; the majority were mild (31.2%; 217/696) or moderate (46.8%; 326/696) in severity. Overall treatment discontinuation was 14.9%; 6.3% due to AEs and <1% due to GI AEs. At Week 48, mean number of gadolinium-enhancing lesions was significantly reduced from baseline (77%; p < 0.0001) and adjusted annualized relapse rate was low (0.16; 95% confidence interval: 0.13-0.20). CONCLUSION: Interim data from EVOLVE-MS-1 suggest DRF is a well-tolerated treatment with a favorable safety/efficacy profile for patients with RRMS.

Incorporating non-linear alignment and multi-compartmental modeling for improved human optic nerve diffusion imaging.

In vivo human optic nerve diffusion magnetic resonance imaging (dMRI) is technically challenging with two outstanding issues not yet well addressed: (i) non-linear optic nerve movement, independent of head motion, and (ii) effect from partial-volumed cerebrospinal fluid or interstitial fluid such as in edema. In this work, we developed a non-linear optic nerve registration algorithm for improved volume alignment in axial high resolution optic nerve dMRI. During eyes-closed dMRI data acquisition, optic nerve dMRI measurements by diffusion tensor imaging (DTI) with and without free water elimination (FWE), and by diffusion basis spectrum imaging (DBSI), as well as optic nerve motion, were characterized in healthy adults at various locations along the posterior-to-anterior dimension. Optic nerve DTI results showed consistent trends in microstructural parametric measurements along the posterior-to-anterior direction of the entire intraorbital optic nerve, while the anterior portion of the intraorbital optic nerve exhibited the largest spatial displacement. Multi-compartmental dMRI modeling, such as DTI with FWE or DBSI, was less subject to spatially dependent biases in diffusivity and anisotropy measurements in the optic nerve which corresponded to similar spatial distributions of the estimated fraction of isotropic diffusion components. DBSI results derived from our clinically feasible (∼10 min) optic nerve dMRI protocol in this study are consistent with those from small animal studies, which provides the basis for evaluating the utility of multi-compartmental dMRI modeling in characterizing coexisting pathophysiology in human optic neuropathies.

Histopathological correlation of diffusion basis spectrum imaging metrics of a biopsy-proven inflammatory demyelinating brain lesion: A brief report.

Diffusion basis spectrum imaging (DBSI) models diffusion-weighted magnetic resonance imaging (MRI) signals as a combination of discrete anisotropic diffusion tensors and a spectrum of isotropic diffusion tensors. Here, we report the histopathological correlates of DBSI in the biopsied brain tissue of a patient with an inflammatory demyelinating lesion typical of multiple sclerosis (MS). Increased radial diffusivity (marker of demyelination), decreased fiber fraction (apparent axonal density), elevated nonrestricted isotropic fraction (marker of vasogenic edema), but unchanged axial diffusivity (marker of integrity of residual axons) seen in the lesion appeared consistent with histopathological findings of inflammatory demyelination with relative axonal sparing. Our report supports the application of DBSI as a biomarker in human studies of MS.

Streamlined EDSS for use in multiple sclerosis clinical practice: Development and cross-sectional comparison to EDSS.

BACKGROUND: The Expanded Disability Status Scale (EDSS) is the standard measure of disability in multiple sclerosis clinical trials. The EDSS has limited application in the clinical setting due to required completion time and scoring complexity. Systematically recording an objective, simplified, less time-intensive, and neurologist-derived disability score would be beneficial for patient care. OBJECTIVE: To develop and validate a streamlined version of the Expanded Disability Status Scale (sEDSS) for clinical monitoring. METHODS: The EDSS was modified by eliminating maneuvers with no impact on function, consolidating redundancies, and simplifying scoring. This sEDSS was refined and preliminarily validated using a pilot cohort of 102 patients. Subsequently, the sEDSS was retrospectively validated using 968 patients from the CombiRx trial. We evaluated correlation and agreement between each functional system as well as the overall sEDSS and EDSS. RESULTS: The sEDSS correlated strongly with the EDSS, both overall (Spearman's rho = 0.93) and for each functional system (Spearman's rho 0.65-0.97). Correlation was slightly lower for functional systems where scoring was modified for consolidation and simplification. CONCLUSION: The sEDSS had strong agreement and correlation with the existing EDSS and can provide a useful measure of disability in clinical practice.

Active CMV infection in two patients with multiple sclerosis treated with alemtuzumab.

Alemtuzumab is a humanized monoclonal antibody targeting the surface molecule CD52, resulting in a rapid depletion of innate and adaptive immune cells. Infection rates in multiple sclerosis (MS) treatment trials were higher in alemtuzumab than in interferon beta-treated patients. We report two MS patients who developed cytomegalovirus disease within 1 month after the first 5-day cycle of alemtuzumab. Upon identification and appropriate treatment of the infection, each recovered completely. Neurologists should be aware of this serious but treatable complication.

High-Frequency Learning Goals: Using Self-Regulated Learning to Influence Day-to-Day Practice in Clinical Education.

PROBLEM: Although self-regulated learning (SRL) is considered a fundamental skill that must be developed in physician training, many programs of SRL utilize learning goals that are generated only at the beginning of learning experiences or are widely spaced apart in time. These goals are often not formally shared with those actually working with the learner in the clinical setting. INTERVENTION: We developed a program of written, student-generated weekly learning goals in which students focused on processes of becoming better doctors for their patients. These goals were shared at the beginning of each week with students' clinical teams for feedback and incorporation into the work. CONTEXT: The weekly learning goals program was developed and implemented as part of a required 3rd-year neurology clerkship. At the end of each 4-week clerkship, students were asked to evaluate the program through an anonymous electronic survey utilizing quantitative and open-ended qualitative questions. OUTCOME: Seventy-six of 82 students completed the evaluation survey (93% response rate). Eighty-six percent reported that the weekly learning goals increased their awareness of their thoughts and actions. Seventy-eight percent reported that the learning goals helped to improve their clinical performance to some degree, and 57% reported that the learning goals increased their focus on patient care. Students described a greater sense of focus on self-assessment and accountability from their goals. Students often commented that engagement from attendings and residents regarding their goals was a key element for successful learning from their goals. LESSONS LEARNED: Student-generated weekly learning goals on a neurology clerkship appear to be an effective method to operationalize SRL. For most students, the frequency of the goals allowed for close self-monitoring, and the act of sharing goals with the team opened a new avenue for dialogue between students and their supervisors.

Differentiation and quantification of inflammation, demyelination and axon injury or loss in multiple sclerosis.

Axon injury/loss, demyelination and inflammation are the primary pathologies in multiple sclerosis lesions. Despite the prevailing notion that axon/neuron loss is the substrate of clinical progression of multiple sclerosis, the roles that these individual pathological processes play in multiple sclerosis progression remain to be defined. An imaging modality capable to effectively detect, differentiate and individually quantify axon injury/loss, demyelination and inflammation, would not only facilitate the understanding of the pathophysiology underlying multiple sclerosis progression, but also the assessment of treatments at the clinical trial and individual patient levels. In this report, the newly developed diffusion basis spectrum imaging was used to discriminate and quantify the underlying pathological components in multiple sclerosis white matter. Through the multiple-tensor modelling of diffusion weighted magnetic resonance imaging signals, diffusion basis spectrum imaging resolves inflammation-associated cellularity and vasogenic oedema in addition to accounting for partial volume effects resulting from cerebrospinal fluid contamination, and crossing fibres. Quantitative histological analysis of autopsied multiple sclerosis spinal cord specimens supported that diffusion basis spectrum imaging-determined cellularity, axon and myelin injury metrics closely correlated with those pathologies identified and quantified by conventional histological staining. We demonstrated in healthy control subjects that diffusion basis spectrum imaging rectified inaccurate assessments of diffusion properties of white matter tracts by diffusion tensor imaging in the presence of cerebrospinal fluid contamination and/or crossing fibres. In multiple sclerosis patients, we report that diffusion basis spectrum imaging quantitatively characterized the distinct pathologies underlying gadolinium-enhanced lesions, persistent black holes, non-enhanced lesions and non-black hole lesions, a task yet to be demonstrated by other neuroimaging approaches. Diffusion basis spectrum imaging-derived radial diffusivity (myelin integrity marker) and non-restricted isotropic diffusion fraction (oedema marker) correlated with magnetization transfer ratio, supporting previous reports that magnetization transfer ratio is sensitive not only to myelin integrity, but also to inflammation-associated oedema. Our results suggested that diffusion basis spectrum imaging-derived quantitative biomarkers are highly consistent with histology findings and hold promise to accurately characterize the heterogeneous white matter pathology in multiple sclerosis patients. Thus, diffusion basis spectrum imaging can potentially serve as a non-invasive outcome measure to assess treatment effects on the specific components of underlying pathology targeted by new multiple sclerosis therapies.