Progressive Injury in Chronic Multiple Sclerosis Lesions Is Gender-Specific: A DTI Study

Imaging phenotypic differences in multiple sclerosis: at the crossroads of aging, sex, race, and ethnicity

Clear sex differences are observed in clinical and imaging phenotypes of multiple sclerosis (MS), which evolve significantly over the age spectrum, and more specifically, during reproductive milestones such as pregnancy and menopause. With neuroimaging being an outcome measure and also a key subclinical biomarker of subsequent clinical phenotype in MS, this comprehensive review aims to provide an overview of sex and hormone differences in structural and functional imaging biomarkers of MS, including lesion burden and location, atrophy, white matter integrity, functional connectivity, and iron distribution. Furthermore, how therapies aimed at altering sex hormones can impact imaging of women and men with MS over the lifespan is discussed. This review also explores the key intersection between age, sex, and race/ethnicity in MS, and how this intersection may affect imaging biomarkers of MS.

Longitudinal Effects of Sex, Aging, and Multiple Sclerosis Diagnosis on Function

BACKGROUND

A gap in research about the trajectories of function among men and women aging with functional limitations because of multiple sclerosis (MS) hinders ability to plan for future needs.

OBJECTIVES

Using a biopsychosocial model, we characterize how men and women with MS report changes over time in their function and test how person-level differences in age, diagnosis duration, and sex influence perceived function.

METHODS

A longitudinal study with multiple waves of surveys was used to collect data on participant perceptions of function, as well as demographic and contextual variables. Self-reported functional limitation was measured over a decade. The study participants were community residing with physician-diagnosed MS.

RESULTS

The people with MS had a diagnosis duration of about 13 years and were around 51 years of age, on average, at the start of the study. They were primarily women and non-Hispanic White. We analyzed the data using mixed-effects models. Subject-specific, functional limitation trajectories were described best with a quadratic growth model. Relative to men, women reported lower functional limitation and greater between-person variation and rates of acceleration in functional limitation scores.

DISCUSSION

Results suggest function progressed through two pathways for over a decade, particularly closer to diagnoses. Variability in trajectories between individuals based on sex and years since diagnosis of disease indicates that men and women with MS may experience perceptions of their function with age differently. This has implications for clinician advice to men and women with MS.

Structural and functional brain damage in women with multiple sclerosis: A mini-review of neuroimaging sex-based studies

Neuroimaging literature in healthy humans has shown that there are sex-related differences in healthy brain's anatomical structure, associated function and susceptibility to neurological diseases. This mini-review summarizes findings derived from the current neuroimaging studies focused on sex-related brain structural and functional damage in women with multiple sclerosis (MS). MS is a chronic, multifactorial, immune-mediated disorder of the central nervous system that affects mostly women. Even if recent neuroimaging studies have shed light on distinctive features of sex-related MS differences in brain structural and functional damage, more research is needed to better elucidate sex-related MS pathological changes and susceptibility and to implement sex-tailored treatment strategies in MS.

Association Between Body Mass Index and Response to Disease-Modifying Therapies in Patients With Relapsing-Remitting Multiple Sclerosis at King Abdulaziz University Hospital: A Retrospective Study

Background Multiple sclerosis (MS) is an immune-mediated inflammatory disease that attacks myelinated axons in the central nervous system, destroying the myelin and axon to varying degrees and producing significant physical disability. So far, many studies have found that having a high body mass index (BMI) is associated with severe autoimmune and neurodegenerative disease course. However, the impact of BMI on disease-modifying therapy (DMT) response in terms of decreasing relapses and improving overall health remains unknown. Aims and objectives The study aimed to demonstrate the effect of BMI on DMT responsiveness in patients with relapse-remitting MS at a tertiary hospital. Methods and material A single-center retrospective study was conducted at a tertiary care center in Jeddah, Saudi Arabia. The study included 89 individuals with relapsing-remitting MS who had their BMI measured within six months of their first clinical relapse, as well as their clinical response to the DMT (number of relapses on a single DMT after six months of initiation) and MRI changes (development of new T2 lesions or gadolinium-enhancing lesions on single DMT six months after DMT initiation). Results Demographic data revealed a female predominance of 71.9%, and 51.7% of the patients had a normal weight. The most commonly prescribed DMT was Gilenya at 47.2%. A significant relationship was found between BMI and the total number of clinical relapses (p=0.038), with the co-existence of a positive correlation between BMI and the number of relapses after at least six months of initiation of DMT. Additionally, MS patients who had both positive MRI changes and obesity had a significantly higher BMI mean than non-obese. Conclusion Increased BMI appeared to be associated with a lower response to DMT, as overweight patients had a worse course than normal and underweight patients. Pharmacokinetic differences are the most likely factors implicated in medication responsiveness.

Sex bias in multiple sclerosis and neuromyelitis optica spectrum disorders: How it influences clinical course, MRI parameters and prognosis

This review is a condensed summary of representative articles addressing the sex/gender bias in multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD). The strong effects of sex on the incidence and possibly also the activity and progression of these disorders should be implemented in the evaluation of any phase of clinical research and also in treatment choice consideration in clinical practice and evaluation of MRI parameters. Some relationships between clinical variables and gender still remain elusive but with further understanding of sex/gender-related differences, we should be able to provide appropriate patient-centered care and research.

What Can We Learn from Sex Differences in MS?

Multiple sclerosis (MS) is the major acquired central nervous system disease of young adults. It is a female predominant disease. Multiple aspects of MS are influenced by sex-based differences. This has become an important area of research and study. It teaches us how the impact of sex on a disease can lead to new insights, guidelines, management, and treatments.

SeXX Matters in Multiple Sclerosis

Multiple sclerosis (MS) is the most common chronic inflammatory and neurodegenerative disease of the central nervous system (CNS). An interesting feature that this debilitating disease shares with many other inflammatory disorders is that susceptibility is higher in females than in males, with the risk of MS being three times higher in women compared to men. Nonetheless, while men have a decreased risk of developing MS, many studies suggest that males have a worse clinical outcome. MS exhibits an apparent sexual dimorphism in both the immune response and the pathophysiology of the CNS damage, ultimately affecting disease susceptibility and progression differently. Overall, women are predisposed to higher rates of inflammatory relapses than men, but men are more likely to manifest signs of disease progression and worse CNS damage. The observed sexual dimorphism in MS may be due to sex hormones and sex chromosomes, acting in parallel or combination. In this review, we outline current knowledge on the sexual dimorphism in MS and discuss the interplay of sex chromosomes, sex hormones, and the immune system in driving MS disease susceptibility and progression.

Sex-specific differences in rim appearance of multiple sclerosis lesions on quantitative susceptibility mapping

BACKGROUND

Susceptibility MRI techniques, such as phase and quantitative susceptibility mapping (QSM) reveal lesion heterogeneity in MS, including the presence of lesions with outer rims suggestive of iron accumulation in macrophages and microglia, indicative of chronic-active inflammatory white matter lesions (WMLs).

OBJECTIVE

To evaluate the in vivo relationship between chronic-active WMLs (as visualized by rimmed lesions on QSM) and several clinical metrics.

METHODS

39 patients (15 men, 24 women) with MS underwent 7 Tesla brain MRIs and clinical evaluation. Contrast patterns of lesions identified on FLAIR and quantitative susceptibility maps were reviewed and compared to demographic characteristics and disability scores.

RESULTS

1279 lesions were identified on FLAIR MRI; 846 (66.2%) of these were visible on QSM, 119 (14.1%) of which had visible rims. Lesions visible on QSM were more likely to have rims in men (16.1%, vs 4.9% in women, p=0.009). In a logistic regression model accounting for several factors, male sex conferred a >10-fold risk of having ≥1 rimmed lesion(s) (p=0.026).

CONCLUSION

Our findings provide in vivo support for the body of histopathologic literature indicating sex-specific differences in MS WML formation and suggest that QSM can be used to study these sex differences in the future.

Value of fluid-attenuated inversion recovery MRI data analyzed by the lesion segmentation toolbox in amyotrophic lateral sclerosis

Background

MRI fluid‐attenuated inversion recovery (FLAIR) studies reported hyperintensity in the corticospinal tract and corpus callosum of patients with amyotrophic lateral sclerosis (ALS).

Purpose

To evaluate the lesion segmentation toolbox (LST) for the objective quantification of FLAIR lesions in ALS patients.

Study Type

Retrospective.

Population

Twenty‐eight ALS patients (eight females, mean age: 50 range: 24–73, mean ALSFRS‐R sum score: 36) were compared with 31 age‐matched healthy controls (12 females, mean age: 45, range: 25–67). ALS patients were treated with riluzole and additional G‐CSF (granulocyte‐colony stimulating factor) on a named patient basis.

Field Strength/Sequence

1.5 T, FLAIR, T₁‐weighted MRI.

Assessment

The lesion prediction algorithm (LPA) of the LST enabled the extraction of individual binary lesion maps, total lesion volume (TLV), and number (TLN). Location and overlap of FLAIR lesions across patients were investigated by registration to FLAIR average space and an atlas. ALS‐specific functional rating scale revised (ALSFRS‐R), disease progression, and survival since diagnosis served as clinical correlates.

Statistical Tests

Univariate analysis of variance (ANOVA), repeated‐measures ANOVA, t‐test, Bravais‐Pearson correlation, Chi‐square test of independence, Kaplan–Meier analysis, Cox‐regression analysis.

Results

Both ALS patients and healthy controls exhibited FLAIR alterations. TLN significantly depended on age (F(1,54) = 24.659, P < 0.001) and sex (F(1,54) = 5.720, P = 0.020). ALS patients showed higher TLN than healthy controls depending on sex (F(1, 54) = 5.076, P = 0.028). FLAIR lesions were small and most pronounced in male ALS patients. FLAIR alterations were predominantly detected in the superior and posterior corona radiata, anterior capsula interna, and posterior thalamic radiation. Patients with pyramidal tract (PT) lesions exhibited significantly inferior survival than patients without PT lesions (P = 0.013). Covariate age exhibited strong prognostic value for survival (P = 0.015).

Data Conclusion

LST enables the objective quantification of FLAIR alterations and is a potential prognostic biomarker for ALS.

Level of Evidence: 3

Technical Efficacy: Stage 2

J. Magn. Reson. Imaging 2019;50:552–559.

White matter tract-specific quantitative analysis in multiple sclerosis: Comparison of optic radiation reconstruction techniques

The posterior visual pathway is commonly affected by multiple sclerosis (MS) pathology that results in measurable clinical and electrophysiological impairment. Due to its highly structured retinotopic mapping, the visual pathway represents an ideal substrate for investigating patho-mechanisms in MS. Therefore, a reliable and robust imaging segmentation method for in-vivo delineation of the optic radiations (OR) is needed. However, diffusion-based tractography approaches, which are typically used for OR segmentation are confounded by the presence of focal white matter lesions. Current solutions require complex acquisition paradigms and demand expert image analysis, limiting application in both clinical trials and clinical practice. In the current study, using data acquired in a clinical setting on a 3T scanner, we optimised and compared two approaches for optic radiation (OR) reconstruction: individual probabilistic tractography-based and template-based methods. OR segmentation results were applied to subjects with MS and volumetric and diffusivity parameters were compared between OR segmentation techniques. Despite differences in reconstructed OR volumes, both OR lesion volume and OR diffusivity measurements in MS subjects were highly comparable using optimised probabilistic tractography-based, and template-based, methods. The choice of OR reconstruction technique should be determined primarily by the research question and the nature of the available dataset. Template-based approaches are particularly suited to the semi-automated analysis of large image datasets and have utility even in the absence of dMRI acquisitions. Individual tractography methods, while more complex than template based OR reconstruction, permit measurement of diffusivity changes along fibre bundles that are affected by specific MS lesions or other focal pathologies.

Enlarged Virchow Robin spaces associate with cognitive decline in multiple sclerosis

The clinical significance of Virchow Robin spaces (VRS) in inflammatory brain disorders, especially in multiple sclerosis (MS), is still undefined. We analysed enlarged VRS (eVRS) by means of phase sensitive inversion recovery (PSIR) MRI sequence and investigated their association with inflammation or brain atrophy, and to clinical or physical disability. Forty-three MS patients (21 clinically isolated syndrome suggestive of MS [CIS], 15 RRMS, 7 progressive [PMS]) and 10 healthy controls (HC) were studied. 3DT1, 3DFLAIR and 2DPSIR images were obtained with a 3T MRI scanner. eVRS number and volume were calculated by manual segmentation (ITK-SNAP). Freesurfer was used to assess brain parenchymal fraction (BPF). All patients underwent clinical (EDSS) and cognitive (Rao’s BRB and DKEFS) evaluation.

eVRS number and volume resulted significantly higher on 2D-PSIR compared to both 3D-T1 (p<0.001) and 3D-FLAIR (p<0.001) and were significantly increased in CIS compared to HC (p<0.05), in PMS and RRMS compared to CIS (p<0.001) and in male versus female patients (p<0.05). eVRS volume increased significantly with disease duration (r = 0.6) but did not correlate with EDSS. eVRS significantly correlated with SPARTd (r = -0.47) and DKEFSfs (r = -0.46), especially when RRMS and PMS were merged in a single group (r = 0.89, p = 0.002 and r = 0.66, p = 0.009 respectively), while no correlation was found with BPF (r = 0.3), gadolinium-enhancing lesions (r = 0.2) and WMT2 lesion volume (r = 0.2). 2DPSIR allowed the detection of an impressive higher number of eVRS compared to 3DT1 and 3DFLAIR. eVRS associate with SPARTd and DKEFSfs failure in relapse-onset MS, suggesting they may contribute to cognitive decline in MS.

Validation of an automated tractography method for the optic radiations as a biomarker of visual acuity in neurofibromatosis-associated optic pathway glioma

INTRODUCTION

Fractional anisotropy (FA) of the optic radiations has been associated with vision deficit in multiple intrinsic brain pathologies including NF1 associated optic pathway glioma, but hand-drawn regions of interest used in previous tractography methods limit consistency of this potential biomarker. We created an automated method to identify white matter tracts in the optic radiations and compared this method to previously reported hand-drawn tractography.

METHOD

Automated tractography of the optic radiation using probabilistic streamline fiber tracking between the lateral geniculate nucleus of the thalamus and the occipital cortex was compared to the hand-drawn method between regions of interest posterior to Meyer's loop and anterior to tract branching near the calcarine cortex. Reliability was assessed by two independent raters in a sample of 20 healthy child controls. Among 50 children with NF1-associated optic pathway glioma, the association of FA and visual acuity deficit was compared for both tractography methods.

RESULTS

Hand-drawn tractography methods required 2.6±0.9min/participant; automated methods were performed in <1min of operator time for all participants. Cronbach's alpha was 0.83 between two independent raters for FA in hand-drawn tractography, but repeated automated tractography resulted in identical FA values (Cronbach's alpha=1). On univariate and multivariate analyses, FA was similarly associated with visual acuity loss using both methods. Receiver operator characteristic curves of both multivariate models demonstrated that both automated and hand-drawn tractography methods were equally able to distinguish normal from abnormal visual acuity.

CONCLUSION

Automated tractography of the optic radiations offers a fast, reliable and consistent method of tract identification that is not reliant on operator time or expertise. This method of tract identification may be useful as DTI is developed as a potential biomarker for visual acuity.

Structural sex differences at disease onset in multiple sclerosis patients

BACKGROUND

Male sex is associated with worsening disability and a more rapid progression of multiple sclerosis (MS). This study analysed structural sex differences in magnetic resonance images of the brain, comparing women whose disease started before and after the menopause with a control group of men.

METHODS

This was a case control study in which female patients whose MS started before (Group 1) and after (Group 2) the menopause were included. The control group was matched by age, disease duration, Expanded Disability Status Scale and disease-modifying treatment. Patients were analysed according to demographic and clinical variables, as well as in terms of radiological measurements at disease onset and during the first 12 months of follow-up. These measurements included normalised total brain volume (NTBV), normalised cortical volume (NCV), normalised white matter volume, left and right hippocampus, the thalamus, brain stem volume, lesion load and percentage brain volume change. A linear regression model was used to analyse the data.

RESULTS

A total of 97 patients were included: 53 in Group 1 (27 females) and 44 in Group 2 (22 females). In Group 1, we observed a reduction in brain volume in males compared with females at disease onset in NTBV (p = 0.01), NCV (p = 0.001) and brain stem volume (p = 0.01). We did not observe differences in Group 2 at disease onset in the brain volumes analysed.

CONCLUSION

We observed structural sex differences in brain volume at disease onset in the pre-menopausal group. However, no structural differences were observed at disease onset between the sexes after the menopause had started.