Fatigue in Multiple Sclerosis: Neural Correlates and the Role of Non-Invasive Brain Stimulation

Hand fatigability, self-reported fatigue, and functionality in individuals with multiple sclerosis: A cross-sectional study

BACKGROUND

The individual experience of fatigue and fatigability in individuals with Multiple Sclerosis (MS) can vary greatly, beyond the high prevalence of fatigue in MS. Although fatigue is known as a common symptom that affects and potentially limits individuals with MS, it has recently been determined that fatigability also causes consequences that limit individuals' daily lives. The purpose of this study was to compare the associations between self-reported levels of fatigue, measured fatigability, and estimates of functional capacity in people with MS and sex- and age-matched healthy individuals.

METHODS

Twenty-three individuals with Relapsing-Remitting MS (RRMS) diagnosis and 23 age- and sex-matched healthy individuals were included in the study. To examine the fatigability level Dynamic and Static Fatigue Index were used for gross and pinch-grip, and manual dexterity and functionality levels the Scale for the Assessment and Rating of Ataxia (SARA), Nine Hole Peg Test (NHPT), and Dexterity Questionnaire-24 (DextQ-24) were used. While the Fatigue Severity Scale (FSS) and Fatigue Impact Scale (FIS) were used to examine self-reported fatigue, the Beck Depression Inventory (BDI) was used to assess emotional status.

RESULTS

There was no difference between RRMS and healthy individuals in terms of fatigability levels (p > 0.05). While the relationship between Static and Dynamic Fatigue Index gross grip fatigability and FSS and FIS was not found to be statistically significant, the relationship between non-dominant side pinch grip Static Fatigue Index and FSS and FIS was significant. In addition, the relationship between the non-dominant side gross grip Static Fatigue Index and the DextQ-24 dressing and daily activities subsections, and the dominant side pinch grip Dynamic Fatigue Index and the television/compact disk/digital video disk subsection of DextQ-24 was significant (p < 0.05).

CONCLUSION

Fatigability was related to daily life upper limb use for gross grip and self-reported fatigue for pinch grip in individuals with RRMS. It was concluded that future studies focusing on hand fatigability could also consider manual dexterity and self-reported fatigue in individuals with MS from the early-stage. Clarifying the relationship of between fatigability and self-reported fatigue to functioning will allow clinicians to plan more appropriate and directed treatment approaches for individuals with RRMS.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05880745.

Disrupted hemodynamic response within dorsolateral prefrontal cortex during cognitive tasks among people with multiple sclerosis-related fatigue

INTRODUCTION

Mental fatigue is an early and enduring symptom in persons with autoimmune disease particularly multiple sclerosis (MS). Neuromodulation has emerged as a potential treatment although optimal cortical targets have yet to be determined. We aimed to examine cortical hemodynamic responses within bilateral dorsolateral prefrontal cortex (dlPFC) and frontopolar areas during single and dual cognitive tasks in persons with MS-related fatigue compared to matched controls.

METHODS

We recruited persons (15 MS and 12 age- and sex-matched controls) who did not have physical or cognitive impairment and were free from depressive symptoms. Functional near infrared spectroscopy (fNIRS) registered hemodynamic responses during the tasks. We calculated oxyhemoglobin peak, time-to-peak, coherence between channels (a potential marker of neurovascular coupling) and functional connectivity (z-score).

RESULTS

In MS, dlPFC demonstrated disrupted hemodynamic coherence during both single and dual tasks, as evidenced by non-significant and negative correlations between fNIRS channels. In MS, reduced coherence occurred in left dorsolateral PFC during the single task but occurred bilaterally as the task became more challenging. Functional connectivity was lower during dual compared to single tasks in the right dorsolateral PFC in both groups. Lower z-score was related to greater feelings of fatigue. Peak and time-to-peak hemodynamic response did not differ between groups or tasks.

CONCLUSIONS

Hemodynamic responses were inconsistent and disrupted in people with MS experiencing mental fatigue, which worsened as the task became more challenging. Our findings point to dlPFC, but not frontopolar areas, as a potential target for neuromodulation to treat cognitive fatigue.

Brain stimulation for patients with multiple sclerosis: an umbrella review of therapeutic efficacy

Multiple sclerosis patients often experience various symptoms that can greatly impact their quality of life. There are various brain stimulation techniques that have been evaluated for their ability to reduce the symptoms of multiple sclerosis. However, there is inconsistency in the specific stimulation methods used and the symptoms targeted in the existing research. This umbrella review conducted in order to evaluate the effectiveness of brain stimulation and identify limitations and gaps for further research. In this umbrella review, we conducted a searched on Web of Knowledge, PubMed, and Scopus database. We specifically looked for reviews, with or without meta-analyses, that have investigated the effects of brain stimulation methods on symptoms of multiple sclerosis. All articles were examined by AMSTAR 2 (A Measure Tool to Assess Systematic Review 2). We identified 155 articles, of which 14 were eligible for inclusion. Of those, five were qualitative studies and nine were meta-analyses. Among the included studies, four examined the use of deep brain stimulation, while ten investigated the therapeutic potential of noninvasive brain stimulation. Considering the heterogeneity of studies, the current evidence suggests that repetitive transcranial magnetic stimulation may be effective in treating pain and improving motor function, while transcranial direct current stimulation may be useful in alleviating fatigue and enhancing certain aspects of cognitive performance. Deep brain stimulation, on the other hand, appears to be effective in reducing tremors. However, further research is warranted to validate these findings and address the existing limitations in the field.

Comparing the effects of cerebellar and prefrontal anodal transcranial direct current stimulation concurrent with postural training on balance and fatigue in patients with multiple sclerosis: a double-blind, randomized, sham-controlled trial

Fatigue and balance disorders are common challenges experienced by Multiple Sclerosis (MS) individuals. The purpose of this study was to compare the concurrent effects of cerebellar and prefrontal anodal trans-cranial direct current stimulation (a-tDCS) with postural training on balance and fatigue in MS patients. 51 patients were evaluated to randomly allocation to a-tDCS over cerebellum, a-tDCS over dorsolateral prefrontal cortex (DLPFC) and sham group. 46 individuals (n = 16 in experimental groups and n = 14 in control group) followed treatment. All the groups received 10 sessions of postural training. The experimental groups underwent a-tDCS with a current of 1.5 mA for a period of 20 min. While, in the sham group, tDCS was only activated for 30 s and then turned off. The treatment included 10 sessions for four weeks. Before and after intervention, fatigue and balance were assessed using Fatigue Severity Scale (FSS), Timed Up and Go (TUG) test and Berg Balance Score (BBS), respectively. There was found a significant reduction in fatigue in the group receiving a-tDCS over the prefrontal cortex with postural training compared to the other two groups (P < 0.001). Additionally, a significant improvement was found in balance in the group receiving a-tDCS over the cerebellum concurrent with postural training in comparison to the other two groups (P < 0.001). Besides, in the sham group, the significant results were not reported in the variables. (P > 0.001). The results demonstrated that a-tDCS enhances the effects of postural training on balance and fatigue in MS patients.

Efficacy and Safety of Ponesimod Compared with Teriflunomide in Female Patients with Relapsing Multiple Sclerosis: Findings from the Pivotal OPTIMUM Study

Background: Multiple sclerosis (MS) is threefold more prevalent in women than men. However, sex-specific efficacy analysis for MS disease-modifying therapies is not typically performed. Methods: Post hoc analyses of data from female patients enrolled in the phase 3, double-blind OPTIMUM study of relapsing MS were carried out. Eligible adults were randomized to ponesimod 20 mg or teriflunomide 14 mg once daily for up to 108 weeks. The primary endpoint was annualized relapse rate (ARR); secondary endpoints included change in symptom domain of Fatigue Symptom and Impact Questionnaire-Relapsing Multiple Sclerosis (FSIQ-RMS) at week 108, number of combined unique active lesions (CUALs) per year on magnetic resonance imaging, and time to 12- and 24-week confirmed disability accumulation (CDA). Results: A total of 735 female patients (581 of childbearing potential) were randomized to ponesimod (n = 363, 49.4%) or teriflunomide (n = 372, 50.6%). Relative risk reduction in the ARR for ponesimod versus teriflunomide was 33.1% (mean, 0.192 vs. 0.286, respectively; p < 0.002). Mean difference in FSIQ-RMS for ponesimod versus teriflunomide was -4.34 (0.12 vs. 4.46; p = 0.002); rate ratio in CUALs per year, 0.601 (1.45 vs. 2.41; p < 0.0001), and hazard ratio for time to 12- and 24-week CDA risk estimates, 0.83 (10.7% vs. 12.9%; p = 0.38) and 0.91 (8.8% vs. 9.7%; p = 0.69), respectively. Incidence of treatment-emergent adverse events was similar between treatment groups (89.0% and 90.1%). Conclusions: Analyses demonstrate the efficacy and safety of ponesimod, versus active comparator, for women with relapsing MS, supporting data-informed decision-making for women with MS. Clinical Trial Registration Number: NCT02425644.

Brain connectivity changes underlying depression and fatigue in relapsing-remitting multiple sclerosis: A systematic review

Multiple Sclerosis (MS) is an autoimmune disease affecting the central nervous system, characterised by neuroinflammation and neurodegeneration. Fatigue and depression are common, debilitating, and intertwined symptoms in people with relapsing-remitting MS (pwRRMS). An increased understanding of brain changes and mechanisms underlying fatigue and depression in RRMS could lead to more effective interventions and enhancement of quality of life. To elucidate the relationship between depression and fatigue and brain connectivity in pwRRMS we conducted a systematic review. Searched databases were PubMed, Web-of-Science and Scopus. Inclusion criteria were: studied participants with RRMS (n ≥ 20; ≥ 18 years old) and differentiated between MS subtypes; published between 2001-01-01 and 2023-01-18; used fatigue and depression assessments validated for MS; included brain structural, functional magnetic resonance imaging (fMRI) or diffusion MRI (dMRI). Sixty studies met the criteria: 18 dMRI (15 fatigue, 5 depression) and 22 fMRI (20 fatigue, 5 depression) studies. The literature was heterogeneous; half of studies reported no correlation between brain connectivity measures and fatigue or depression. Positive findings showed that abnormal cortico-limbic structural and functional connectivity was associated with depression. Fatigue was linked to connectivity measures in cortico-thalamic-basal-ganglial networks. Additionally, both depression and fatigue were related to altered cingulum structural connectivity, and functional connectivity involving thalamus, cerebellum, frontal lobe, ventral tegmental area, striatum, default mode and attention networks, and supramarginal, precentral, and postcentral gyri. Qualitative analysis suggests structural and functional connectivity changes, possibly due to axonal and/or myelin loss, in the cortico-thalamic-basal-ganglial and cortico-limbic network may underlie fatigue and depression in pwRRMS, respectively, but the overall results were inconclusive, possibly explained by heterogeneity and limited number of studies. This highlights the need for further studies including advanced MRI to detect more subtle brain changes in association with depression and fatigue. Future studies using optimised imaging protocols and validated depression and fatigue measures are required to clarify the substrates underlying these symptoms in pwRRMS.

Sleep Disorders and Fatigue among Patients with MS: The Role of Depression, Stress, and Anxiety

Sleep disorders and fatigue represent prominent symptoms frequently experienced by individuals with multiple sclerosis (MS). Some psychological factors such as depression, stress, and anxiety seem to have a relationship with such problems. This study aimed to examine the role of depression, stress, and anxiety in predicting sleep disorders and fatigue among patients with MS. Employing a cross-sectional descriptive-correlational design, the study involved a sample size of 252 participants selected through purposive sampling based on inclusion and exclusion criteria. We utilized a demographic information questionnaire along with the Mini-Sleep Questionnaire (MSQ), Fatigue Severity Scale (FSS), and Depression, Anxiety, and Stress Scale (DASS-21) to collect data and analyzed them applying SPSS22, incorporating statistical measures including Pearson correlation and regression. The results of the Pearson correlation coefficient showed that sleep disorders had a positive and significant relationship with depression (r = 0.56; P < 0.001), stress (r = 0.40; P < 0.001), and anxiety (r = 0.52; P < 0.001). There was no significant relationship between age and the development of sleep disorders in total score (r = -0.001; P < 0.985), but age had a relationship with insomnia (r = -0.146; P < 0.021) and oversleeping (r = 0.153; P < 0.015). Age and fatigue did not have a significant relationship as well (r = -0.044; P < 0.941). In addition, fatigue had a positive and significant relationship with depression (r = 0.52; P < 0.001), stress (r = 0.48; P < 0.001), and anxiety (r = 0.54; P < 0.001). The results of the regression analysis also showed that depression, stress, and anxiety predict 0.37% of the total variance of sleep disorders (F = 48.34; P < 0.001) and 0.35% of the total variance of fatigue (F = 44.64; P < 0.001). Our findings suggest that depression, stress, and anxiety play a significant role in predicting sleep disorders and fatigue among patients with MS. This study has been reported in accordance with the TREND checklist for nonrandomized trials.

Frequency and characteristics of chronic fatigue syndrome in multiple sclerosis patients at a university hospital in Eastern Saudi Arabia

BACKGROUND

Multiple sclerosis (MS) is a chronic, inflammatory demyelinating disease that affects various parts of the central nervous system. Fatigue, a common symptom, transient, prolonged, or chronic experienced by individuals with MS, can significantly impact daily functioning. It can be associated with underlying pathological processes or can have an idiopathic cause, such as chronic fatigue syndrome (CFS). The study aimed to assess the presence and etiology of fatigue in MS patients and its relationship with CFS.

MATERIALS AND METHODS

This cross-sectional study was conducted in the Eastern Province of Saudi Arabia. Data were collected using a questionnaire from a sample of 225 MS patients receiving care at our university hospital. The questionnaire included the Centers for Disease Control and Prevention (CDC) criteria for diagnosing CFS and the Expanded Disability Status Scale to evaluate fatigue in MS patients.

RESULTS

Of the total of 225 MS patients who participated in this study, 87.1% were diagnosed with relapsing-remitting MS, 6.7% with primary progressive MS, 3.6% with clinically isolated syndrome, and 2.7% with secondary progressive MS. About 53% had experienced fatigue that persisted for over 6 months. Analysis of CFS diagnosis revealed that 7.3% of patients met both CDC criteria and self-reported answers while 17.5% reported having CFS despite not meeting the CDC criteria. These findings highlight a significant lack of agreement between patient-reported diagnoses and established criteria, indicating poor agreement (P = 0.028).

CONCLUSION

The study found an association between CFS and MS, and a significant impact on daily functioning. The study revealed lack of agreement between patient-reported diagnoses and established criteria for CFS. This emphasizes the need for a standardized approach to diagnosis and evaluation of fatigue in MS patients.

Transcranial direct current stimulation for fatigue in neurological conditions: A systematic scoping review

BACKGROUND AND PURPOSE

Fatigue following neurological conditions negatively impacts daily activities, reducing overall quality of life. Transcranial direct current stimulation (tDCS) for fatigue management is still underexplored. This scoping review explores its use in managing fatigue among various neurological conditions.

METHODS

A thorough literature search was carried out using PubMed, Scopus, CINAHL, Web of Science, Embase, ProQuest, and the Cochrane Library. Google Scholar and clinicaltrials.gov were manually searched for gray literature and ongoing trials, respectively. Regardless of the study design, all studies utilizing tDCS for the management of fatigue in various neurological conditions were considered. Two reviewers independently screened all the studies, following which the data were retrieved.

RESULTS

Studies employing tDCS for fatigue management across neurological conditions is as follows: Multiple sclerosis (MS) (n = 28, 66%), stroke (n = 5, 12%), Parkinson's disease (PD) (n = 4, 10%), post-polio syndrome (PPS) (n = 2, 5%), traumatic brain injury (TBI) (n = 2, 5%), and amyotrophic lateral sclerosis (n = 1, 2%). All the studies used anodal stimulation, with the common stimulation site being the left dorsolateral prefrontal cortex for MS, stroke, and PD. A stimulation intensity of 1.0-4.0 mA with a duration ranging from 15 to 30 min in 1 to 24 sessions were commonly reported. The Fatigue Severity Scale (n = 21) and Modified Fatigue Impact Scale (n = 17) were frequently implemented outcome measures. Regardless of the study design, 36/42 (85.7%) studies reported an improvement in fatigue scores in the tDCS group. The common adverse events noted were tingling (n = 8, 35%), headache (n = 6, 26%), and itching (n = 6, 26%).

DISCUSSION

Application of tDCS for fatigue was explored in individuals with stroke, PD, PPS, and TBI after MS. Even though a wide range of treatment parameters and outcome measures were adopted to assess and target fatigue, tDCS proves to have a promising role in alleviating this symptom.

Diffusion tensor imaging changes of the cortico-thalamic-striatal tracts correlate with fatigue and disability in people with relapsing-remitting MS

PURPOSE

To investigate how the microstructural neural integrity of cortico-thalamic-striatal (CTS) tracts correlate with fatigue and disability over time. The primary outcome was diffusion tensor imaging (DTI) metrics change over time, and the secondary outcome was correlations with fatigue and disability in people with RRMS (pw-RRMS).

METHODS

76 clinically stable pw-RRMS and 43 matched healthy controls (HCs). The pw-RRMS cohort consisted of three different treatment subgroups. All participants underwent disability, cognitive, fatigue and mental health assessments. Structural and diffusion scans were performed at baseline (BL) and 2-year follow-up (2-YFU) for all participants. Fractional anisotropy (FA), mean, radial and axial diffusivities (MD, RD, AD) of normal-appearing white matter (NAWM) and white matter lesion (WML) in nine tracts-of-interests (TOIs) were estimated using our MRtrix3 in-house pipeline.

RESULTS

We found significant BL and 2-YFU differences in most diffusion metrics in TOIs in pw-RRMS compared to HCs (pFDR ≤ 0.001; false-detection-rate (FDR)-corrected). There was a significant decrease in WML diffusivities and an increase in FA over the follow-up period in most TOIs (pFDR ≤ 0.001). Additionally, there were no differences in DTI parameters across treatment groups. AD and MD were positively correlated with fatigue scores (r ≤ 0.33, p ≤ 0.01) in NAWM-TOIs, while disability (EDSS) was negatively correlated with FA in most NAWM-TOIs (|r|≤0.31, p ≤ 0.01) at both time points. Disability scores correlated with all diffusivity parameters (r ≤ 0.29, p ≤ 0.01) in most WML-TOIs at both time points.

CONCLUSION

Statistically significant changes in diffusion metrics in WML might be indicative of integrity improvement over two years in CTS tracts in clinically stable pw-RRMS. This finding represents structural changes within lesioned tracts. Measuring diffusivity in pw-RRMS affected tracts might be a relevant measure for future remyelination clinical trials.

Electrical stimulation therapy for pain and related symptoms in multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

The effectiveness of electrical stimulation therapy (EST) for pain, depression, fatigue, disability, and quality of life in multiple sclerosis (MS) remains uncertain. This study aims to analyze and discuss the efficacy of various EST treatments in alleviating pain among MS patients.

METHODS

The primary search was conducted using PubMed, Web of Science, Cochrane Library, Embase, and the Cumulative Index of Nursing and Allied Health Literature databases until September 25, 2023. Randomized controlled trials (RCTs) including patients with MS pain receiving EST compared with other therapies were included. Pain intensity, quality of life, and neuropsychiatric symptoms were reported. The mean difference (MD) with 95 % confidence intervals (CIs) was estimated separately for outcomes to understand the mean effect size.

RESULTS

Ten RCTs containing 315 participants were included. The pooled data from 8 trials including 267 participants showed that the EST was superior in alleviating pain (MD = -1.75, 95 % CI -2.85--0.64, P = 0.002, I2=73 %) evaluated by the visual analog scale. In subgroup analysis, medium-term EST treatment showed the highest effect size compared to short-term and long-term treatment (MDmedium-term = -2.17, 95 % CI -3.51--0.84, P = 0.001, I2 = 0 %). However, no significant differences were found in terms of pain-related quality of life, depression, fatigue, and pain-related disability. No adverse events related to EST were reported. A high risk of bias was identified in three of the ten included studies.

CONCLUSIONS

EST is effective and safe for alleviating pain in MS, but it should be noted that limited sample sizes and methodological issues were present in the included studies. More robust assessment criteria and high-quality RCTs are required for patients with MS.

TRIAL REGISTRATION

CRD42023406787. (https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=406787).

Management of multiple sclerosis fatigue in the digital age: from assessment to treatment

Fatigue is one of the most disabling symptoms of Multiple Sclerosis (MS), affecting more than 80% of patients over the disease course. Nevertheless, it has a multi-faceted and complex nature, making its diagnosis, evaluation, and treatment extremely challenging in clinical practice. In the last years, digital supporting tools have emerged to support the care of people with MS. These include not only smartphone or table-based apps, but also wearable devices or novel techniques such as virtual reality. Furthermore, an additional effective and cost-efficient tool for the therapeutic management of people with fatigue is becoming increasingly available. Virtual reality and e-Health are viable and modern tools to both assess and treat fatigue, with a variety of applications and adaptability to patient needs and disability levels. Most importantly, they can be employed in the patient's home setting and can not only bridge clinic visits but also be complementary to the monitoring and treatment means for those MS patients who live far away from healthcare structures. In this narrative review, we discuss the current knowledge and future perspectives in the digital management of fatigue in MS. These may also serve as sources for research of novel digital biomarkers in the identification of disease activity and progression.

[Alexithymia in Multiple Sclerosis - Narrative Review]

Alexithymia is a multidimensional construct of personality implicating difficulties in identifying and describing another's feelings, and externally oriented thinking. It is broadly reported in psychiatric patients but has gained little attention regarding its occurrence and pathophysiology in multiple sclerosis (MS). This narrative review aims to address prevalence, etiology, neurobiological, and clinical findings of alexithymia. The prevalence of alexithymia in MS ranges from 10 to 53%. There seems to be an association with anxiety, depression, fatigue, and some aspects of social cognition, while the relationship with clinical and classical cognitive variables was rarely evaluated. Only a few studies referred to its pathophysiology assuming an aberrant interhemispheric transfer or regional cerebral abnormalities. The prevalence of alexithymia in MS and the potential negative impact on quality of life and interpersonal communication could severely impact clinical MS management and a screnning for these factors should be mandatory. Thus, further evaluation is needed concerning its relationship with clinical, emotional, and cognitive confounders. Large-scale studies employing neuroimaging techniques are needed for a better understanding of the neural underpinnings of this MS feature.

Muscle Coactivation Index during Walking in People with Multiple Sclerosis with Mild Disability, a Cross-Sectional Study

BACKGROUND

Multiple sclerosis (MS) is a progressive neurodegenerative disease characterized by axonal degeneration and demyelination. Changes in gait, related to joint kinematics and kinetics, especially at the ankle and knee, have been observed in people with MS (pwMS). Muscle coactivation plays an important role in joint stabilization; however, excessive coactivation may interfere with gait. The aim of this study was to analyze the differences in muscle activation during gait in pwMS compared to healthy individuals.

METHODS

A cross-sectional study was conducted involving pwMS and healthy controls. Surface electromyography was used to record muscle activity during gait. The main outcome measures were the coactivation index (CI) and the area under the curve (AUC), which were calculated for several pairs of lower extremity muscles.

RESULTS

Nine pwMS and nine healthy controls were included. When comparing the MS group to the control group, the AUC was significantly higher in the lateral gastrocnemius (p = 0.023) and the CI for the lateral gastrocnemius-anterior tibialis (p = 0.022) and gluteus maximus-lateral gastrocnemius (p = 0.047).

CONCLUSION

Mildly affected pwMS have altered muscle coactivation patterns during gait, especially in the most affected limb. The results highlight the importance of muscle coactivation in pwMS and its possible role in the early detection of gait abnormalities.

Role of selective attention in fatigue in neurological disorders

BACKGROUND

Chronic fatigue is a significant symptom in several diseases including traumatic and degenerative neurological disorders. While several studies have investigated the correlates of chronic fatigue, there is as yet no unifying framework to explain chronic fatigue.

METHODS

In this narrative review, I investigate the role of selective attention in the development of chronic fatigue and discuss results within the framework of the sensory attenuation model of fatigue, which posits that fatigue is the phenomenological output of altered attention to sensory input. Following a short introduction of this framework, I present results from investigations that address attentional mechanisms in fatigue in multiple sclerosis, stroke, traumatic brain injury and Parkinson's disease.

RESULTS

Attention was quantified in all four disease models using a variety of outcome measures, including behavioural, neurophysiological, structural and functional brain connectivity. The range of measures precluded direct comparison of results across disease conditions; however, in all four disease models there was evidence of poor selective attention that explained levels of chronic fatigue, supporting the sensory attenuation model of fatigue as a disease-independent mechanism of fatigue. Evidence was lacking to draw any conclusions about the direction of causality.

CONCLUSION

The role of selective attention in development of fatigue is indicated. Future studies must focus on establishing causality and exploring attentional circuitry as a potential therapeutic target.

[Toward a better understanding of fatigue in schizophrenia]

Despite being one of the most common complaints of people with schizophrenia, fatigue remains largely unexplored in this population. The lack of knowledge regarding this complex symptom makes it often underdiagnosed and undertreated in schizophrenia. The aim of this brief perspective review is to outline the potential origins (distinguishing primary and secondary fatigue) and consequences of fatigue and to explore some potential treatments in this population. The current literature in schizophrenia has mainly investigated fatigue as a trait, using a self-administered questionnaire. Beyond this observational approach, which does not allow to capture the symptom in real life situations where high levels of fatigue can emerge rapidly, we propose to consider the state level of fatigue, for instance occurring after a prolonged period of cognitive activity (i.e. mental fatigue). We elaborate on the potential relationships between mental fatigue and negative symptoms of schizophrenia and propose some research avenues to test the effects of acute fatigue on effort intentions and behaviours. The consideration of the multidimensional aspects of fatigue will allow to move beyond the sole pharmacological approach to treat fatigue in schizophrenia. Targeting the cognitive as well as the performance components of fatigue through interventions such as concomitant aerobic exercise - mental training offers attractive prospects to reduce fatigue in this population and minimize its functional negative impact.

A virtual reality program to assess cognitive function in multiple sclerosis: A pilot study

Introduction: Cognitive impairment is a debilitating symptom in people with multiple sclerosis (MS). Most of the neuropsychological tasks have little resemblance to everyday life. There is a need for ecologically valid tools for assessing cognition in real-life functional contexts in MS. One potential solution would involve the use of virtual reality (VR) to exert finer control over the task presentation environment; however, VR studies in the MS population are scarce.

Objectives: To explore the utility and feasibility of a VR program for cognitive assessment in MS.

Methods: A VR classroom embedded with a continuous performance task (CPT) was assessed in 10 non-MS adults and 10 people with MS with low cognitive functioning. Participants performed the CPT with distractors (i.e., WD) and without distractors (i.e., ND). The Symbol Digit Modalities Test (SDMT), California Verbal Learning Test—II (CVLT-II), and a feedback survey on the VR program was administered.

Results: People with MS exhibited greater reaction time variability (RTV) compared to non-MS participants, and greater RTV in both WD and ND conditions was associated with lower SDMT.

Conclusions: VR tools warrant further research to determine their value as an ecologically valid platform for assessing cognition and everyday functioning in people with MS.

Neural bases of motor fatigue in multiple sclerosis: A multimodal approach using neuromuscular assessment and TMS-EEG

Motor fatigue is one of the most common symptoms in multiple sclerosis (MS) patients. Previous studies suggested that increased motor fatigue in MS may arise at the central nervous system level. However, the mechanisms underlying central motor fatigue in MS are still unclear. This paper investigated whether central motor fatigue in MS reflects impaired corticospinal transmission or suboptimal primary motor cortex (M1) output (supraspinal fatigue). Furthermore, we sought to identify whether central motor fatigue is associated with abnormal M1 excitability and connectivity within the sensorimotor network. Twenty-two patients affected by relapsing-remitting MS and 15 healthy controls (HCs) performed repeated blocks of contraction at different percentages of maximal voluntary contraction with the right first dorsal interosseus muscle until exhaustion. Peripheral, central, and supraspinal components of motor fatigue were quantified by a neuromuscular assessment based on the superimposed twitch evoked by peripheral nerve and transcranial magnetic stimulation (TMS). Corticospinal transmission, excitability and inhibition during the task were tested by measurement of motor evoked potential (MEP) latency, amplitude, and cortical silent period (CSP). M1 excitability and connectivity was measured by TMS-evoked electroencephalography (EEG) potentials (TEPs) elicited by M1 stimulation before and after the task. Patients completed fewer blocks of contraction and showed higher values of central and supraspinal fatigue than HCs. We found no MEP or CSP differences between MS patients and HCs. Patients showed a post-fatigue increase in TEPs propagation from M1 to the rest of the cortex and in source-reconstructed activity within the sensorimotor network, in contrast to the reduction observed in HCs. Post-fatigue increase in source-reconstructed TEPs correlated with supraspinal fatigue values. To conclude, MS-related motor fatigue is caused by central mechanisms related explicitly to suboptimal M1 output rather than impaired corticospinal transmission. Furthermore, by adopting a TMS-EEG approach, we proved that suboptimal M1 output in MS patients is associated with abnormal task-related modulation of M1 connectivity within the sensorimotor network. Our findings shed new light on the central mechanisms of motor fatigue in MS by highlighting a possible role of abnormal sensorimotor network dynamics. These novel results may point to new therapeutical targets for fatigue in MS.

Long-term dietary acid load is associated with depression in multiple sclerosis, but less evidence was found with fatigue and anxiety

BACKGROUND

Diet-dependent acid-base load has been associated with worsening in mental health, but to date no study has examined this in people with multiple sclerosis (PwMS). We examined the association between potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores and depression, anxiety, and fatigue in PwMS.

METHODS

Participants with a first clinical diagnosis of CNS demyelination were followed prospectively as part of the AusLong Study (aged 18-59 years at cohort entry). At baseline, 5- and 10-year reviews, PRAL and NEAP scores were calculated using dietary intake in the preceding 12 months calculated from a food frequency questionnaire. At 5- and 10-year reviews, the Hospital Anxiety and Depression Scale was used to assess depression and anxiety, and the Fatigue Severity Scale assessed fatigue.

RESULTS

Higher PRAL and NEAP scores were associated with increased subsequent absolute value and change in HADS depression scores over five years' follow-up (e.g., highest vs lowest PRAL quartile, 5-year change in HADS-D score: β=+3.01, 95%CI= 1.54, 4.48, p<0.001). The level of depression at the 10-year review was determined by both the baseline dietary acid scores and baseline-5-year changes in dietary acid scores (e.g., PRAL change from baseline to 5-year review, 10-year review HADS-D score: β=+0.09, 95%CI= 0.03, 0.15, p<0.001, NEAP change from baseline to 5-year review, 10-year review HADS-D score: β=+0.07, 95%CI= 0.01, 0.14, p=0.03). Some associations were observed with anxiety and fatigue but were much weaker and less consistent.

CONCLUSION

Our findings indicate that a higher dietary acid load potentially has a long-term influence on the level of depression in PwMS. The evidence is less convincing for anxiety and fatigue.

Non-invasive brain stimulation therapy on neurological symptoms in patients with multiple sclerosis: A network meta analysis

OBJECTIVE

The aim of the study was to evaluate non-invasive brain stimulation (NIBS) [including transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES)] on neurological symptoms in patients with multiple sclerosis (PwMS).

METHOD

We searched PubMed, Embase, Cochrane Library, Web of Science and Ovid MEDLINE until February 2022. And we evaluated the included studies for methodological quality by the Cochrane bias risk assessment tool and assessed the studies' certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. We performed network meta analysis (NMA) by using Stata 15 and ranked the results of the NMA by using the surface under the cumulative ranking curve (SUCRA) ranking chart.

RESULT

Twenty seven clinical trials were finally included (N = 596, 66.4% women). For the immediate effects, rTMS over M1 yielded the most optimal scheme for fatigue reduction among all the interventions compared to the sham stimulation groups [MD = -0.85, 95% CI (-1.57, -0.14)] (SUCRA = 82.6%). iTBS over M1 yielded the most signifcant reduced pain level than the sham groups did [MD = -1.26, 95% CI (-2.40, -0.11)] (SUCRA = 98.4%). tDCS over F3 was the best protocol of NIBS to improve quality of life (QOL) [MD = 1.41, 95% CI = (0.45,2.36)] (SUCRA = 76.7%), and iTBS over M1 may significantly reduce spasticity compared to sham stimulation [MD = -1.20, 95% CI = (-1.99, -0.41)] (SUCRA = 90.3%). Furthermore, rTMS, tRNS, and tDCS on certain areas may improve PwMS accuracy, response time, manual dexterity, pain relief and QOL, but does not show statistically significant differences. The evidence assessed using GRADE is very low.

CONCLUSION

Based on the NMA and SUCRA ranking, we can conclude that symptoms including fatigue, pain, spasticity, and QOL can be improved by following NIBS protocol after treatment. Nonetheless, most of the included studies lack a good methodology, and more high-quality randomized clinical trials are needed.

How is neuromuscular fatigability affected by perceived fatigue and disability in people with multiple sclerosis?

Whereas fatigue is recognized to be the main complaint of patients with multiple sclerosis (PwMS), its etiology, and particularly the role of resistance to fatigability and its interplay with disability level, remains unclear. The purposes of this review were to (i) clarify the relationship between fatigue/disability and neuromuscular performance in PwMS and (ii) review the corticospinal and muscular mechanisms of voluntary muscle contraction that are altered by multiple sclerosis, and how they may be influenced by disability level or fatigue. Neuromuscular function at rest and during exercise are more susceptible to impairement, due to deficits in voluntary activation, when the disability is greater. Fatigue level is related to resistance to fatigability but not to neuromuscular function at rest. Neurophysiological parameters related to signal transmission such as central motor conduction time, motor evoked potentials amplitude and latency are affected by disability and fatigue levels but their relative role in the impaired production of torque remain unclear. Nonetheless, cortical reorganization represents the most likely explanation for the heightened fatigability during exercise for highly fatigued and/or disabled PwMS. Further research is needed to decipher how the fatigue and disability could influence fatigability for an ecological task, especially at the corticospinal level.

Mapping grip-force related brain activity after a fatiguing motor task in multiple sclerosis

BACKGROUND

Motor fatigue is common in multiple sclerosis (MS), but its pathophysiology is still poorly understood. Here we used functional magnetic resonance imaging (fMRI) to delineate how the acute induction of motor fatigue alters functional activity of the motor system and how these activity changes are related to motor fatigue.

METHOD

Forty-four right-handed mildly disabled patients with relapsing-remitting MS and 25 healthy controls performed a maximal tonic precision grip with their right hand until they developed motor fatigue. Before and after the fatiguing task, participants performed a non-fatiguing tonic grip force task, producing 15-20% of their maximum grip force based on visual feedback. Task related brain activity was mapped with blood-oxygen level dependent fMRI at 3 T. Statistical parametric mapping was used to identify relative changes in task-related activation from the pre-fatigue to the recovery MRI session.

RESULTS

Following fatigue induction, task performance was perturbed in both groups, and task-related activation increased in the right (ipsilateral) primary motor hand area. In patients with MS, task-related activity increased bilaterally during the recovery phase in the ventrolateral portion of the middle putamen and lateral prefrontal cortex relative to controls. The more patients increased task-related activity in left dorsal premotor cortex after the fatiguing task, the less they experienced motor fatigue during daily life.

CONCLUSION

Patients with MS show enhanced functional engagement of the associative cortico-basal ganglia loop following acute induction of motor fatigue in the contralateral hand. This may reflect increased mental effort to generate movements in the recovery phase after fatigue induction. The ability to recruit the contralateral dorsal premotor cortex after fatigue induction may constitute a protective mechanism against experiencing motor fatigue in everyday life.

People with multiple sclerosis have reduced TMS-evoked motor cortical output compared with healthy individuals during fatiguing submaximal contractions

People with multiple sclerosis (PwMS) typically experience greater levels of exercise-induced fatigue compared with healthy individuals. Therefore, this study examined performance fatigability in PwMS when executing a prolonged submaximal contraction. Nine PwMS (38 ± 7 yr, 6 females) and nine healthy controls (35 ± 6 yr, 4 females) performed an elbow flexion at 15% maximal voluntary contraction (MVC) for 26 min. MVCs were performed every 2 min during, and following, the contraction to determine if maximal force was impaired by the low-intensity contraction. Single-pulse transcranial magnetic stimulation (TMS) was delivered to the primary motor cortex with a circular coil during each MVC and during the submaximal contraction. Superimposed and resting twitches were calculated from elbow flexion torque, whereas motor-evoked potentials were calculated from biceps brachii electromyography. Ratings of perceived exertion (RPE) were obtained before each MVC. During the fatiguing contraction protocol, the MS group exhibited a reduced MVC torque compared with the healthy control group (P = 0.044), which aligned with group differences in biceps brachii EMG activity (P = 0.022) and superimposed twitch amplitude (P = 0.016). Fatigue-related decrements in MVC torque (P = 0.044) and biceps brachii EMG activity (P = 0.043) demonstrated in the MS group persisted throughout recovery. However, MS did not affect the RPE during the fatigue task. These findings suggest that PwMS may have greater levels of performance fatigability due to decreased voluntary drive from the motor cortex, which is not associated with greater ratings of perceived exertion.NEW & NOTEWORTHY By combining TMS and motor nerve stimulation during a low-intensity exercise task, we were able to uncover the contribution that different levels of the CNS have during fatiguing exercise in PwMS. Our findings are novel and revealed that PwMS experienced decreased voluntary drive from the motor cortex during a low-intensity sustained fatiguing task that was associated with heightened levels of performance fatigability.

The Neurobiology of Pathological Fatigue: New Models, New Questions

The last decade has seen the emergence of new theoretical frameworks to explain pathological fatigue, a much neglected, yet highly significant symptom across a wide range of diseases. While the new models of fatigue provide new hypotheses to test, they also raise a number of questions. The primary purpose of this essay is to examine the predictions of three recently proposed models of fatigue, the overlap and differences between them, and the evidence from diseases that may lend support to the models of fatigue. I also present expansions for the sensory attenuation model of fatigue. Further questions examined here are the following: What are the neural substrates of fatigue? How can sensory attenuation, which underpins agency also explain fatigue? Are fatigue and agency related?

Fatigue in Multiple Sclerosis: A Review of the Exploratory and Therapeutic Potential of Non-Invasive Brain Stimulation

Fatigue is the most commonly reported symptom in patients with multiple sclerosis (MS). It is a worrisome, frequent, and debilitating manifestation that could occur at any time during the course of MS and in all its subtypes. It could engender professional, familial, and socioeconomic consequences and could severely compromise the patients' quality of life. Clinically, the symptom exhibits motor, cognitive, and psychosocial facets. It is also important to differentiate between perceived or subjective self-reported fatigue and fatigability which is an objective measure of decrement in the performance of cognitive or motor tasks. The pathophysiology of MS fatigue is complex, and its management remains a challenge, despite the existing body of literature on this matter. Hence, unraveling its neural mechanisms and developing treatment options that target the latter might constitute a promising field to explore. A PubMed/Medline/Scopus search was conducted to perform this review which aims (a) to reappraise the available electrophysiological studies that explored fatigue in patients with MS with a particular focus on corticospinal excitability measures obtained using transcranial magnetic stimulation and (b) to assess the potential utility of employing neuromodulation (i.e., non-invasive brain stimulation techniques) in this context. A special focus will be put on the role of transcranial direct current stimulation and transcranial magnetic stimulation. We have provided some suggestions that will help overcome the current limitations in upcoming research.

Fatigue, Depression, and Anxiety Among Ambulating Multiple Sclerosis Patients

Background

Multiple sclerosis (MS) is an inflammatory disease associated with adverse effects: including depression, anxiety, fatigue, which may affect physical activity and the quality of life (QoL) among patients with MS (pwMS).

Objective

This study aims to assess the prevalence of depression, anxiety, and fatigue among pwMS who have no physical disability in Saudi Arabia, and demonstrate any correlation between these factors and physical activity as well as the QoL.

Methods

A cross-sectional study was conducted in the Neuroimmunology outpatient clinics in King Fahad Medical City (KFMC) and King Saud University Medical City (KSUMC) in Riyadh City, KSA. The Arabic version of the Hospital Anxiety and Depression Scale (HADS) was used to measure anxiety and depression levels. The HADS scores were then categorized into three levels according to the total points: normal (0–7 points), borderline (7–10 points), and anxiety/depression (11 – 21 points). The Arabic version of the Fatigue Severity Scale (FSS) was used to measure fatigue (cut-off point ≥5). The physical activity was measured by the Arabic version of the short form of the International Physical Activity Questionnaire (IPAQ), which measure time spent walking, moderate- and vigorous-intensity physical activity of at least 10 minutes duration. The QoL was also measured by the Arabic version of the EuroQOL five-dimensional (EQ-5D-3L) instrument (i.e., mobility, self-care, usual activities, pain/discomfort, and anxiety/depression).

Results

A total of 323 pwMS participated in this study, 83 had scores that indicated anxiety (25.7%) and 44 had depression (13.6%). The majority of patients had scores with the normal range of depression and anxiety (70% and 57% respectively). The mean of EuroQol Group visual analogue scale (EQ-VAS) score was 80.43 (SD=19.8). 156 (48.3%) out of 323 pwMS reported fatigue while the remainder had no fatigue (n=167, 51.7%). The results indicate that only 143 patients (44.3%) had participated in vigorous physical activity during the last 70 days, with a median of 3 days per week (IQR= 5–3) and a median of 60 minutes per day 0 (Interquartile range: IQR = 60–30). Only 149 patients (49.2%) had patricpated in moderate physical activities during the previous week with a median of 3 days per week (IQR = 5–3) and a median of 40 minutes per day (IQR = 60–30). 194 patients had participated in walking activities (60.0%) with a median of 5 days per week (IQR = 7–3) and a median of 45 minutes per day (IQR = 60–30). The results revealed that fatigue was positively correlated with depression (r = 0.407, p-value < 0.001) and anxiety (r = 0.289, p-value < 0.001).

Conclusion

The current study shows depression, anxiety, and fatigue tend to be correlated and clustered together among pwMS in our cohort. However, fatigue is not associated with the intensity of physical activity undertaken. The results of this study are important for the improvement of the clinical management of MS patients.

Evaluation of Muscle Synergy during Exoskeleton-assisted Walking in Persons with Multiple Sclerosis

OBJECTIVE

Gait deficit after multiple sclerosis (MS) can be characterized by altered muscle activation patterns. There is preliminary evidence of improved walking with a lower limb exoskeleton in persons with MS. However, the effects of exoskeleton-assisted walking on neuromuscular modifications are relatively unclear. The objective of this study was to investigate the muscle synergies, their activation patterns and the differences in neural strategies during walking with (EXO) and without (No-EXO) an exoskeleton.

METHODS

Ten subjects with MS performed walking during EXO and No-EXO conditions. Electromyography signals from seven leg muscles were recorded. Muscle synergies and the activation profiles were extracted using non-negative matrix factorization.

RESULTS

The stance phase duration was significantly shorter during EXO compared to the No-EXO condition (p<0.05). Moreover, typically 3-5 modules were extracted in each condition. The module-1 (comprising Vastus Medialis and Rectus Femoris muscles), module-2 (comprising Soleus and Medial Gastrocnemius muscles), module-3 (Tibialis Anterior muscle) and module-4 (comprising Biceps Femoris and Semitendinosus muscles) were comparable between conditions. During EXO condition, Semitendinosus and Vastus Medialis emerged in module-5 in 7/10 subjects. Compared to No-EXO, average activation amplitude was significantly reduced corresponding to module-2 during the stance phase and module-3 during the swing phase during EXO.

CONCLUSION

Exoskeleton-assistance does not alter the existing synergy modules, but could induce a new module to emerge, and alters the control of these modules, i.e., modifies the neural commands indicated by the reduced amplitude of the activation profiles.

Signal Detection Theory as a Novel Tool to Understand Cognitive Fatigue in Individuals With Multiple Sclerosis

Multiple Sclerosis (MS) affects 2.8 million persons worldwide. One of the most persistent, pervasive, and debilitating symptoms of MS is cognitive fatigue. While this has been known for over a century, cognitive fatigue has been difficult to study because patients' subjective (self-reported) cognitive fatigue has consistently failed to correlate with more objective measures, such as reaction time (RT) and accuracy. Here, we investigated whether more nuanced metrics of performance, specifically the metrics of Signal Detection Theory (SDT), would show a relationship to cognitive fatigue even if RT and accuracy did not. We also measured brain activation to see whether SDT metrics were related to activation in brain areas that have been shown to be sensitive to cognitive fatigue. Fifty participants (30 MS, 20 controls) took part in this study and cognitive fatigue was induced using four blocks of a demanding working memory paradigm. Participants reported their fatigue before and after each block, and their performance was used to calculate SDT metrics (Perceptual Certainty and Criterion) and RT and accuracy. The results showed that the SDT metric of Criterion (i.e., response bias) was positively correlated with subjective cognitive fatigue. Moreover, the activation in brain areas previously shown to be related to cognitive fatigue, such as the striatum, was also related to Criterion. These results suggest that the metrics of SDT may represent a novel tool with which to study cognitive fatigue in MS and other neurological populations. These results hold promise for characterizing cognitive fatigue in MS and developing effective interventions in the future.

Perceived Fatigue Impact and Cognitive Variability in Multiple Sclerosis

OBJECTIVE

People with Multiple Sclerosis (PwMS) and healthy controls (HCs) were evaluated on cognitive variability indices and we examined the relationship between fatigue and cognitive variability between these groups. Intraindividual variability (IIV) on a neuropsychological test battery was hypothesized to mediate the group differences expected in fatigue.

METHOD

Fifty-nine PwMS and 51 HCs completed a psychosocial interview and battery of neuropsychological tests and questionnaires during a 1-day visit. Fatigue in this study was measured with the Fatigue Impact Scale (FIS), a self-report multidimensional measure of fatigue. IIV was operationalized using two different measures, a maximum discrepancy score (MDS) and intraindividual standard deviation (ISD), in two cognitive domains, memory and attention/processing speed. Two mediation analyses with group (PwMS or HCs) as the independent variable, variability composite (memory or attention/processing speed) measures as the mediators, total residual fatigue (after accounting for age) as the outcome, and depression as a covariate were conducted. The Baron and Kenny approach to testing mediation and the PROCESS macro for testing the strength of the indirect effect were used.

RESULTS

Results of a mediation analysis using 5000 bootstrap samples indicated that IIV in domains of both attention/processing speed and memory significantly mediated the effect of patient status on total residual fatigue.

CONCLUSION

IIV is an objective performance measure that is related to differences in fatigue impact between PwMS and HCs. PwMS experience more variability across tests of attention/processing speed and memory and this experience of variable performance may increase the impact of fatigue.

Effects of non-invasive brain stimulation in multiple sclerosis: systematic review and meta-analysis

Objective:

The objective of this meta-analysis was to summarize evidence on the therapeutic effects of non-invasive brain stimulation (NIBS) on core symptoms of multiple sclerosis (MS). Specifically, findings from studies deploying transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) protocols were summarized in this review.

Methods:

We systematically searched articles published in four databases, until 31 May 2021, which compared the effects of active tDCS or rTMS with sham intervention in MS patients. We used a random-effects model for this meta-analysis. Meta-regression and subgroup meta-analysis were used to examine the effects of stimulation dose and different stimulation protocols, respectively.

Results:

Twenty-five randomized controlled trials (RCTs) were included in this review, consisting of 19 tDCS and 6 rTMS studies. tDCS led to a significant and immediate reduction of fatigue with a large effect size (Hedges’s g = −0.870, 95% confidence intervals (CI) = [−1.225 to −0.458], number needed to treat (NNT) = 2). Particularly, a subgroup analysis showed that applying tDCS over the left DLPFC and bilateral S1 led to fatigue reductions compared to sham stimulation. Furthermore, tDCS had favorable effects on fatigue in MS patients with low physical disability but not those with high physical disability, and additionally improved cognitive function. Finally, whereas rTMS was observed to reduce muscle spasticity, these NIBS protocols showed no further effect on MS-associated pain and mood symptoms.

Conclusion:

tDCS in MS alleviates fatigue and improves cognitive function whereas rTMS reduces muscle spasticity. More high-quality studies are needed to substantiate the therapeutic effects of different NIBS protocols in MS.

Subcortical volumes as early predictors of fatigue in multiple sclerosis

OBJECTIVE

Fatigue is a frequent and severe symptom in multiple sclerosis (MS), but its pathophysiological origin remains incompletely understood. We aimed to examine the predictive value of subcortical gray matter volumes for fatigue severity at disease onset and after four years by applying structural equation modeling (SEM).

METHODS

This multi-center cohort study included 601 treatment-naive MS patients after the first demyelinating event. All patients underwent a standardized 3T MRI protocol. A subgroup of 230 patients with available clinical follow-up data after four years was also analyzed. Associations of subcortical volumes (included into SEM) with MS-related fatigue were studied regarding their predictive value. In addition, subcortical regions that have a central role in the brain network (hubs) were determined through structural covariance network (SCN) analysis.

RESULTS

Predictive causal modeling identified volumes of the caudate (s [standardized path coefficient]=0.763, p=0.003 [left]; s=0.755, p=0.006 [right]), putamen (s=0.614, p=0.002 [left]; s=0.606, p=0.003 [right]) and pallidum (s=0.606, p=0.012 [left]; s=0.606, p=0.012 [right]) as prognostic factors for fatigue severity in the cross-sectional cohort. Moreover, the volume of the pons was additionally predictive for fatigue severity in the longitudinal cohort (s=0.605, p=0.013). In the SCN analysis, network hubs in patients with fatigue worsening were detected in the putamen (p=0.008 [left]; p=0.007 [right]) and pons (p=0.0001).

INTERPRETATION

We unveiled predictive associations of specific subcortical gray matter volumes with fatigue in an early and initially untreated MS cohort. The colocalization of these subcortical structures with network hubs suggests an early role of these brain regions in terms of fatigue evolution. This article is protected by copyright. All rights reserved.

Quantitative body symmetry assessment during neurological examination

BACKGROUND

A lack of movement coordination characterized by the undershoot or overshoot of the intended location with the hand, arm, or leg is often found in individuals with multiple sclerosis (MS). Standardized as Finger-to-Nose (FNT) and The Heel-to-Shin (HST) tests are the most frequently used tests for qualitative examination of upper and lower body coordination. Inertial sensors facilitate in performing quantitative motion analysis and by estimating body symmetry more accurately assess coordination lesion and imbalance.

OBJECTIVES

To assess the body symmetry of upper and lower limbs quantitatively, and to find the best body symmetry indices to discriminate MS from healthy individuals (CO).

METHODS

28 MS patients and 23 CO participated in the study. Spatiotemporal parameters obtained from six Inertial Measurement Units (IMUs) were placed on the upper and lower extremities during FNT and HST tests. All data were analyzed using statistical methods in MATLAB.

RESULTS

Asymmetry indices of temporal parameters showed a significant increase in upper body and lower body asymmetry of MS compared to CO. However, CO have a greater kinematic asymmetry compared to MS.

CONCLUSION

Temporal parameters are the most sensitive to body asymmetry evaluation. However, range of motion is completely inappropriate if it is calculated for one movement cycle.

Are near visual signs and symptoms in multiple sclerosis compatible with convergence insufficiency?

CLINICAL RELEVANCE

Optometric management of neurodegenerative diseases is essential since visual signs, such as double vision, visual acuity reduction, or oculomotricity dysfunctions, are usually present in these subjects over the course of the disease. The present paper can guide clinicians in better managing their patients with multiple sclerosis.

BACKGROUND

Patients with multiple sclerosis present near vision symptoms that may be related to binocular anomalies, but these symptoms have not been investigated and related to specific signs. The aim of the present study was to evaluate the binocular vision in subjects with multiple sclerosis, and to analyse if the near visual signs and symptoms observed are compatible with those found in convergence insufficiency, as occurs in other neurodegenerative diseases.

METHODS

A total of 57 multiple sclerosis patients and 26 healthy controls were examined and classified as potentially compatible with convergence insufficiency according to the signs and symptoms. Clinical diagnosis of convergence insufficiency was established when subjects met the following criteria: NPC breakpoint more than 6 cm, PFV ≤ than 15^Δ (base-out), and exophoria greater at near than at distance at least 4^Δ. Convergence Insufficiency Symptom Survey (CISS) was administered to assess the symptomatology considering a score ≥16 as positive.

RESULTS

According to the CISS score, 54,4% of the multiple sclerosis subjects revised showed a suspect of convergence insufficiency, with a median score of 27 (IQR 9), whereas only one subject from control group (3.8%) showed this suspect. According to the diagnostic criteria based on signs, only 15.8% of multiple sclerosis patients had a real diagnosis of convergence insufficiency.

CONCLUSION

Multiple sclerosis patients showed symptomatology compatible with convergence insufficiency, but this was not supported by the signs which showed a more esophoric tendency. The discrepancies between the signs and symptoms could be due to the questionnaire used including items that are also related to the cognitive function and other ocular abnormalities.

Ponesimod Compared With Teriflunomide in Patients With Relapsing Multiple Sclerosis in the Active-Comparator Phase 3 OPTIMUM Study: A Randomized Clinical Trial

Importance

To our knowledge, the Oral Ponesimod Versus Teriflunomide In Relapsing Multiple Sclerosis (OPTIMUM) trial is the first phase 3 study comparing 2 oral disease-modifying therapies for relapsing multiple sclerosis (RMS).

Objective

To compare the efficacy of ponesimod, a selective sphingosine-1-phosphate receptor 1 (S1P1) modulator with teriflunomide, a pyrimidine synthesis inhibitor, approved for the treatment of patients with RMS.

Design, Setting, and Participants

This multicenter, double-blind, active-comparator, superiority randomized clinical trial enrolled patients from April 27, 2015, to May 16, 2019, who were aged 18 to 55 years and had been diagnosed with multiple sclerosis per 2010 McDonald criteria, with a relapsing course from the onset, Expanded Disability Status Scale (EDSS) scores of 0 to 5.5, and recent clinical or magnetic resonance imaging disease activity.

Interventions

Patients were randomized (1:1) to 20 mg of ponesimod or 14 mg of teriflunomide once daily and the placebo for 108 weeks, with a 14-day gradual up-titration of ponesimod starting at 2 mg to mitigate first-dose cardiac effects of S1P1 modulators and a follow-up period of 30 days.

Main Outcomes and Measures

The primary end point was the annualized relapse rate. The secondary end points were the changes in symptom domain of Fatigue Symptom and Impact Questionnaire-Relapsing Multiple Sclerosis (FSIQ-RMS) at week 108, the number of combined unique active lesions per year on magnetic resonance imaging, and time to 12-week and 24-week confirmed disability accumulation. Safety and tolerability were assessed. Exploratory end points included the percentage change in brain volume and no evidence of disease activity (NEDA-3 and NEDA-4) status.

Results

For 1133 patients (567 receiving ponesimod and 566 receiving teriflunomide; median [range], 37.0 [18-55] years; 735 women [64.9%]), the relative rate reduction for ponesimod vs teriflunomide in the annualized relapse rate was 30.5% (0.202 vs 0.290; P < .001); the mean difference in FSIQ-RMS, -3.57 (-0.01 vs 3.56; P < .001); the relative risk reduction in combined unique active lesions per year, 56% (1.405 vs 3.164; P < .001); and the reduction in time to 12-week and 24-week confirmed disability accumulation risk estimates, 17% (10.1% vs 12.4%; P = .29) and 16% (8.1% vs 9.9; P = .37), respectively. Brain volume loss at week 108 was lower by 0.34% (-0.91% vs -1.25%; P < .001); the odds ratio for NEDA-3 achievement was 1.70 (25.0% vs 16.4%; P < .001). Incidence of treatment-emergent adverse events (502 of 565 [88.8%] vs 499 of 566 [88.2%]) and serious treatment-emergent adverse events (49 [8.7%] vs 46 [8.1%]) was similar for both groups. Treatment discontinuations because of adverse events was more common in the ponesimod group (49 of 565 [8.7%] vs 34 of 566 [6.0%]).

Conclusions and Relevance

In this study, ponesimod was superior to teriflunomide on annualized relapse rate reduction, fatigue, magnetic resonance imaging activity, brain volume loss, and no evidence of disease activity status, but not confirmed disability accumulation. The safety profile was in line with the previous safety observations with ponesimod and the known profile of other S1P receptor modulators.

Trial Registration

ClinicalTrials.gov Identifier: NCT02425644.

A review of burn symptoms and potential novel neural targets for non-invasive brain stimulation for treatment of burn sequelae

Burn survivors experience myriad associated symptoms such as pain, pruritus, fatigue, impaired motor strength, post-traumatic stress, depression, anxiety, and sleep disturbance. Many of these symptoms are common and remain chronic, despite current standard of care. One potential novel intervention to target these post burn symptoms is transcranial direct current stimulation (tDCS). tDCS is a non-invasive brain stimulation (NIBS) technique that modulates neural excitability of a specific target or neural network. The aim of this work is to review the neural circuits of the aforementioned clinical sequelae associated with burn injuries and to provide a scientific rationale for specific NIBS targets that can potentially treat these conditions. We ran a systematic review, following the PRISMA statement, of tDCS effects on burn symptoms. Only three studies matched our criteria. One was a feasibility study assessing cortical plasticity in chronic neuropathic pain following burn injury, one looked at the effects of tDCS to reduce pain anxiety during burn wound care, and one assessed the effects of tDCS to manage pain and pruritus in burn survivors. Current literature on NIBS in burn remains limited, only a few trials have been conducted. Based on our review and results in other populations suffering from similar symptoms as patients with burn injuries, three main areas were selected: the prefrontal region, the parietal area and the motor cortex. Based on the importance of the prefrontal cortex in the emotional component of pain and its implication in various psychosocial symptoms, targeting this region may represent the most promising target. Our review of the neural circuitry involved in post burn symptoms and suggested targeted areas for stimulation provide a spring board for future study initiatives.

Objective electrophysiological fatigability markers and their modulation through tDCS

OBJECTIVE

Cognitive fatigability is a frequent symptom after sustained performance. Fatigability is evident in healthy subjects but is also often comorbid in several neuropsychiatric diseases. However, to date, clinical diagnostic almost solely relies on the self-reported subjective experience of fatigue. The goals of this present study were i) to complement the purely subjective fatigue diagnostic with objective electrophysiological fatigability parameters and ii) to prove the potential therapeutic application of transcranial direct current stimulation (tDCS) as a fatigability intervention.

METHODS

We performed a pseudo-randomized, sham-controlled, parallel-group trial. Forty healthy participants received either anodal or sham tDCS over the left dorsolateral prefrontal cortex (DLPFC) while they performed an exhaustive cognitive task to induce cognitive fatigability. To assess fatigability changes, we analyzed variations of prepulse inhibition (PPI) and P50 suppression as well as frontomedial theta and occipital alpha power with time-on-task.

RESULTS

The task reliably induced subjective exhaustion in all participants. Furthermore, we confirmed fatigability-related increases in frontomedial theta and occipital alpha power throughout the task. Additionally, fatigability significantly reduced PPI as well as P50 sensory gating. Anodal tDCS over the left DLPFC successfully counteracted fatigability and reduced the fatigability-related increase in alpha power as well as the decline in both gating parameters.

CONCLUSION

Occipital alpha and sensorimotor/sensory gating are suitable parameters to assess the severity of fatigability objectively. Anodal tDCS can counteract fatigability and has therapeutic potential for the treatment of fatigability in neuropsychiatric diseases.

SIGNIFICANCE

Fatigability can be objectively assessed by electrophysiological measures and attenuated by tDCS.

Effect of transcranial direct current stimulation on post-stroke fatigue

Background

Fatigue is one of the most commonly reported symptoms post-stroke, which has a severe impact on the quality of life. Post-stroke fatigue is associated with reduced motor cortical excitability, specifically of the affected hemisphere.

Objective

The aim of this exploratory study was to assess whether fatigue symptoms can be reduced by increasing cortical excitability using anodal transcranial direct current stimulation (tDCS).

Methods

In this sham-controlled, double-blind intervention study, tDCS was applied bilaterally over the primary motor cortex in a single session in thirty stroke survivors with high severity of fatigue. A questionnaire-based measure of trait fatigue (primary outcome) was obtained before, after a week and 5 weeks post stimulation. Secondary outcome measures of state fatigue, motor cortex neurophysiology and perceived effort were also assessed pre, immediately post, a week and 5 weeks post stimulation.

Results

Anodal tDCS significantly improved fatigue symptoms a week after real stimulation when compared to sham stimulation. There was also a significant change in motor cortex neurophysiology of the affected hemisphere and perceived effort, a week after stimulation. The degree of improvement in fatigue was associated with baseline anxiety levels.

Conclusion

A single session of anodal tDCS improves fatigue symptoms with the effect lasting up to a week post stimulation. tDCS may therefore be a useful tool for managing fatigue symptoms post-stroke.

Trial registration

NCT04634864

Date of registration

17/11/2020–“retrospectively registered”.

EEG Correlates of Central Origin of Cancer-Related Fatigue

The neurophysiological mechanism of cancer-related fatigue (CRF) remains poorly understood. EEG was examined during a sustained submaximal contraction (SC) task to further understand our prior research findings of greater central contribution to early fatigue during SC in CRF. Advanced cancer patients and matched healthy controls performed an elbow flexor SC until task failure while undergoing neuromuscular testing and EEG recording. EEG power changes over left and right sensorimotor cortices were analyzed and correlated with brief fatigue inventory (BFI) score and evoked muscle force, a measure of central fatigue. Brain electrical activity changes during the SC differed in CRF from healthy subjects mainly in the theta (4-8 Hz) and beta (12-30 Hz) bands in the contralateral (to the fatigued limb) hemisphere; changes were correlated with the evoked force. Also, the gamma band (30-50 Hz) power decrease during the SC did not return to baseline after 2 min of rest in CRF, an effect correlated with BFI score. In conclusion, altered brain electrical activity during a fatigue task in patients is associated with central fatigue during SC or fatigue symptoms, suggesting its potential contribution to CRF during motor performance. This information should guide the development and use of rehabilitative interventions that target the central nervous system to maximize function recovery.

Fatigue in teriflunomide-treated patients with relapsing remitting multiple sclerosis in the real-world Teri-FAST study

BACKGROUND

Fatigue is a frequent and disabling symptom of multiple sclerosis (MS) often associated with impaired quality of life (QoL) in patients. Teriflunomide is a once-daily oral immunomodulator used for the treatment of relapsing remitting forms of MS. However, its effect on fatigue is not well known in real life practice. We evaluated the impact of teriflunomide on fatigue in patients with relapsing remitting MS (RRMS) after 2 years of treatment in the real-world Teri-FAST study.

METHODS

Teri-FAST was a 2-year, prospective, observational study conducted in France in RRMS patients treated with teriflunomide 14 mg. Fatigue was assessed using the French version of the modified fatigue impact scale (EMIF-SEP). The primary endpoint was the change from baseline in EMIF-SEP score after 2 years of treatment. Secondary endpoints included evaluation of depression (Beck Depression Inventory [BDI]), health-related QoL (Two-Life Scale TLS-QoL 10), self-reported physical activity, and adverse events.

RESULTS

210 eligible patients were included in the study with a mean age of 45.4 years and a mean ± SD Expanded Disability Status Scale score of 1.76 ± 1.43 at baseline. About half (52.4%) of patients had no previous treatment for MS. In the 163 patients who completed at least 1 follow-up visit, the mean change in EMIF-SEP score at Year 2 was -1.54 (95% CI: -4.02, 0.94) indicating that fatigue remained stable. Similarly, there were no changes in depression level and QoL after 2 years of treatment. Physical activity slightly improved with 57% of patients reporting being physically active after 2 years as compared to 46% at baseline. The safety profile of teriflunomide was consistent with that seen during clinical development, and compliance with treatment was high.

CONCLUSION

Fatigue scores remained stable in RRMS patients treated with teriflunomide 14 mg over 2 years in real-life setting. Teriflunomide did not negatively impact depression or QoL.

A cross-sectional study of alexithymia in patients with relapse remitting form of multiple sclerosis

Background:

Alexithymia is one's incapacity to identify, comprehend, and describe emotions. There is almost no literature data about the levels of alexithymia among patients with relapse remitting type of multiple sclerosis.

Aim:

The objective of the present study was to assess the levels of alexithymia in patients with relapse remitting type of multiple sclerosis in relation to their sociodemographic variables and clinical characteristics of the disease.

Methods:

This cross-sectional study included 106 consecutively assessed patients with relapse remitting type of multiple sclerosis. In addition to the data regarding disease duration, number of demyelinating relapses, and degree of neurological disability, assessed by the expanded disability scale score (EDSS), we used Toronto alexithymia scale (TAS), fatigue severity scale (FSS) and, Hamilton scale for the assessment of anxiety and depression and sociodemographic questionnaire.

Results:

Study included 74 female and 32 male patients, with a median age of 44 years, median disease duration 90 months, and median EDSS 4. About 29.55% of patients had alexithymia and borderline alexithymia was observed in 31.15% patients. Alexithymia correlated with anxiety and depression (P < 0.01) on all TAS subscales. Higher levels of neurological disability based on EDSS, severe fatigue based on FSS scores, and severe relapse remitting type of multiple sclerosis with more relapses and longer disease duration correlated with alexithymia (P < 0.01), depression (P < 0.01), and anxiety (P < 0.01). Higher rates of alexithymia were noticed in older, unemployed, single patients, and those having fewer children.

Conclusions:

Alexithymia was found in a relatively high percentage in patients with relapse remitting type of multiple sclerosis.

Fatigue, depression, and pain in multiple sclerosis: How neuroinflammation translates into dysfunctional reward processing and anhedonic symptoms

Fatigue, depression, and pain affect the majority of multiple sclerosis (MS) patients, which causes a substantial burden to patients and society. The pathophysiology of these symptoms is not entirely clear, and current treatments are only partially effective. Clinically, these symptoms share signs of anhedonia, such as reduced motivation and a lack of positive affect. In the brain, they are associated with overlapping structural and functional alterations in areas involved in reward processing. Moreover, neuroinflammation has been shown to directly impede monoaminergic neurotransmission that plays a key role in reward processing. Here, we review recent neuroimaging and neuroimmunological findings, which indicate that dysfunctional reward processing might represent a shared functional mechanism fostering the symptom cluster of fatigue, depression, and pain in MS. We propose a framework that integrates these findings with a focus on monoaminergic neurotransmission and discuss its therapeutic implications, limitations, and perspectives.

New Strategies for Rehabilitation and Pharmacological Treatment of Fatigue Syndrome in Multiple Sclerosis

Multiple sclerosis (MS) is the most common autoimmune disease of the central nervous system (CNS), with an inflammatory demyelinating basis and a progressive course. The course of the disease is very diverse and unpredictable. Patients face many problems on a daily basis, such as problems with vision; sensory, balance, and gait disturbances; pain; muscle weakness; spasticity; tremor; urinary and fecal disorders; depression; and rapidly growing fatigue, which significantly influences quality of life among MS patients. Excessive fatigue occurs in most MS patients in all stages of this disease and is named MS-related fatigue. The crucial issue is the lack of effective treatment; therefore, this review focuses not only on the most common treatment methods, but also on additional novel therapies such as whole-body cryotherapy (WBC), functional electrical stimulation (FES), and non-invasive brain stimulation (NIBS). We also highlight the advantages and disadvantages of the most popular clinical scales used to measure fatigue. The entire understanding of the origins of MS-related fatigue may lead to the development of more effective strategies that can improve quality of life among MS patients. A literature search was performed using MEDLINE, EMBASE, and PEDro databases.

Efficacy and safety of amantadine for the treatment of fatigue in multiple sclerosis: a systematic review and meta-analysis

Background: Fatigue is a debilitating symptom of multiple sclerosis (MS) affecting at least 75% of patients. Amantadine has been tested for MS-related fatigue treatment but efficacy and safety remain unclear. Materials & methods: We performed a systematic review and meta-analysis of qualified literatures searched until 30 April 2020. Results: A total of 11 clinical trials were included. The meta-analysis revealed improvement of MS-related fatigue with amantadine treatment using the patients' subjective responses and validated fatigue scales. Conclusion: Amantadine is the most studied drug that has shown improvement of MS-related fatigue, with mild side effects and good tolerability. Larger studies using a standard measurement for MS-related fatigue are recommended to improve the quality of evidence. Safety and efficacy on long-term use needs further investigation.

Regional microglial activation in the substantia nigra is linked with fatigue in MS

OBJECTIVE

The goal of our study is to assess the role of microglial activation in MS-associated fatigue (MSAF) using [F-18]PBR06-PET.

METHODS

Fatigue severity was measured using the Modified Fatigue Impact Scale (MFIS) in 12 subjects with MS (7 relapsing-remitting and 5 secondary progressive) and 10 healthy control participants who underwent [F-18]PBR06-PET. The MFIS provides a total fatigue score as well as physical, cognitive, and psychosocial fatigue subscale scores. Standardized Uptake Value (SUV) 60-90 minute frame PET maps were coregistered to 3T MRI. Voxel-by-voxel analysis using Statistical Parametric Mapping and atlas-based regional analyses were performed. SUV ratios (SUVRs) were global brain normalized.

RESULTS

Peak voxel-based level of significance for correlation between total fatigue score and PET uptake was localized to the right substantia nigra (T-score 4.67, p = 0.001). Similarly, SUVRs derived from atlas-based segmentation of the substantia nigra showed significant correlation with MFIS (r = 0.76, p = 0.004). On multiple regression, the right substantia nigra was an independent predictor of total MFIS (p = 0.02) and cognitive MFIS subscale values (p = 0.007), after adjustment for age, disability, and depression. Several additional areas of significant correlations with fatigue scores were identified, including the right parahippocampal gyrus, right precuneus, and juxtacortical white matter (all p < 0.05). There was no correlation between fatigue scores and brain atrophy and lesion load in patients with MS.

CONCLUSION

Substantia nigra microglial activation is linked to fatigue in MS. Microglial activation across key brain regions may represent a unifying mechanism for MSAF, and further evaluation of neuroimmunologic basis of MSAF is warranted.

Multiple sclerosis-related fatigue: the role of impaired corticospinal responses and heightened exercise fatigability

It is unclear whether motor fatigability and perceived fatigue share a common pathophysiology in people with multiple sclerosis (PwMS). This cross-sectional investigation explored the relationship between the mechanisms of motor fatigability from cycling and fatigue severity in PwMS. Thirteen highly fatigued (HF) and thirteen nonfatigued (LF) PwMS and thirteen healthy controls (CON) completed a step test until volitional exhaustion on an innovative cycle ergometer. Neuromuscular evaluations involving femoral nerve electrical stimulation and transcranial magnetic stimulation were performed every 3 min throughout cycling. One-way ANOVA at baseline and exhaustion uncovered evidence of consistently smaller motor evoked potential (MEP) amplitudes (P = 0.011) and prolonged MEP latencies (P = 0.041) in HF as well as a greater decline in maximal voluntary contraction force (HF: 63 ± 13%; LF: 75 ± 13%; CON: 73 ± 11% of pre; P = 0.037) and potentiated twitch force (HF: 35 ± 13%; LF: 50 ± 16%; CON: 47 ± 17% of pre; P = 0.049) in HF at volitional exhaustion. Hierarchical regression determined that fatigue severity on the Fatigue Severity Scale was predicted by prolonged MEP latencies (change in r² = 0.389), elevated peripheral muscle fatigability (change in r² = 0.183), and depressive symptoms (change in r² = 0.213). These findings indicate that MS-related fatigue is distinguished by disrupted corticospinal responsiveness, which could suggest progressive pathology, but fatigability from whole body exercise and depressive symptoms also influence perceptions of fatigue in PwMS.NEW & NOTEWORTHY The etiology of fatigability from whole body exercise was examined for the first time to accurately elucidate the relationship between fatigue and fatigability in multiple sclerosis (MS). Compromised corticospinal responsiveness predicted fatigue severity, providing a novel, objective indicator of fatigue in MS. Although the impaired corticomotor transmission did not aggravate muscle activation in this group of people with multiple sclerosis (PwMS) of lower disability, heightened muscle fatigability was seen to contribute to perceptions of fatigue in PwMS.

Repeated and patterned stimulation of cutaneous reflex pathways amplifies spinal cord excitability

Priming with patterned stimulation of antagonist muscle afferents induces modulation of spinal cord excitability as evidenced by changes in group Ia reciprocal inhibition. When assessed transiently with a condition-test pulse paradigm, stimulating cutaneous afferents innervating the foot reduces Ia presynaptic inhibition and facilitates soleus Hoffmann (H)-reflex amplitudes. Modulatory effects (i.e., priming) of longer lasting sensory stimulation of cutaneous afferents innervating the foot have yet to be examined. As a first step, we examined how priming with 20 min of patterned and alternating stimulation between the left and right foot affects spinal cord excitability. During priming, stimulus trains (550 ms; consisting of twenty-eight 1-ms pulses at 51 Hz, 1.2 times the radiating threshold) were applied simultaneously to the sural and plantar nerves of the ankle. Stimulation to the left and right ankle was out of phase by 500 ms. We evoked soleus H-reflexes and muscle compound action potentials (M waves) before and following priming stimulation to provide a proxy measure of spinal cord excitability. H-reflex and M-wave recruitment curves were recorded at rest, during brief (<2 min) arm cycling, and with sural conditioning [train of five 1-ms pulses at 2 times the radiating threshold (RT) with a condition-test interval (C-T) = 80 ms]. Data indicate an increase in H-reflex excitability following priming via patterned sensory stimulation. Transient sural conditioning was less effective following priming, indicating that the increased excitability of the H-reflex is partially attributable to reductions in group Ia presynaptic inhibition. Sensory stimulation to cutaneous afferents, which enhances spinal cord excitability, may prove useful in both rehabilitation and performance settings.NEW & NOTEWORTHY Priming via patterned stimulation of the nervous system induces neuroplasticity. Yet, accessing previously known cutaneous reflex pathways to alter muscle reflex excitability has not yet been examined. Here, we show that sensory stimulation of the cutaneous afferents that innervate the foot sole can amplify spinal cord excitability, which, in this case, is attributed to reductions in presynaptic inhibition.

Sleep in multiple sclerosis patients treated with interferon beta: an actigraphic study

OBJECTIVE

Sleep disorders in multiple sclerosis (MS) patients are common and complex. Some evidences suggest that interferon beta (IFN-β), a first line disease modifying therapy can be involved in the induction of sleep architecture changes. The aim of this study was to evaluate and characterize actigraphic patterns in MS patients treated with IFN-β.

METHODS

Ten relapsing remitting MS patients with low to mild disability (Expanded Disability Status Scale<2.5), aged 20-50y treated with IFN-β for more than 6 months were enrolled. Actigraphy was used to study sleep pattern. Sleep quality was assessed by the Pittsburgh Sleep Quality Index (PSQI). Ten sex-and age-matched healthy subjects served as controls. In patients, a comparison between drug free nights and nights following drug administration was made.

RESULTS

Patients had significantly higher PSQI (p = 0.006), sleep onset latency (p = 0.029), sleep efficiency percentage (p = 0.001) and number of wake episodes (p = 0,0001) values, when compared with controls. When comparing the actigraphic results acquired in the nights after treatment with those acquired in the free-drug nights, the only significant difference (p = 0.038) was detected for time in bed that was higher after IFN-β administration.

CONCLUSIONS

Our results, besides confirming the presence of alterations in sleep patterns in MS patients, suggest that IFN-β may contribute to promote alteration in sleep architecture. Actigraphy is a simple diagnostic tool, able to support an objective measure of sleep parameters. The relative simplicity of application and low costs may allow considering its use for an adequate screening of sleep disorders in MS patients.