Gait and Functional Mobility in Multiple Sclerosis: Immediate Effects of Transcranial Direct Current Stimulation (tDCS) Paired With Aerobic Exercise

Non-invasive brain stimulation enhances the effect of physiotherapy for balance and mobility impairment in people with Multiple Sclerosis

BACKGROUND

Impairment of balance and gait is common in Multiple Sclerosis (MS). Non-invasive Brain Stimulation techniques are promising adjuncts to physical therapy to improve disability.

OBJECTIVE

To determine if combining transcranial direct current stimulation (tDCS) with conventional exercise therapy enhances balance and mobility in people with multiple sclerosis (PwMS) compared to exercise alone.

METHODS

In a double-blind randomised controlled trial, PwMS were randomised into a real or sham tDCS group. All patients received individualized exercise treatment. Twelve sessions of real (intensity 2mA, bipolar) or sham tDCS was administered over the primary motor area for 20 minutes followed by one hour of physiotherapy focusing on balance, strength, and mobility, twice a week for six weeks. Outcome measures included balance (Berg Balance Score), mobility (10m Walk Test), fatigue (Fatigue Severity Scale) and quality of life (Multiple Sclerosis Quality of Life - 54) performed 1 week before intervention, at week 7 (1-week post-intervention), and at six months post-intervention. Falls questionnaire was completed 1 week before intervention and at 6 months post-intervention. Generalised linear mixed model analysis was used to compare outcomes at different time points within groups (before and after exercise treatment) and between groups (sham vs real stimulation groups).

RESULTS

Forty participants (mean age 54 and mean EDSS 3.5) were randomly allocated to receive real (n=19) or sham (n=21) stimulation, with 36 completing the post-intervention (real 17, sham 19) and 32 completing the 6-month assessments (real 15, sham 17). All participants had significantly improved balance and mobility scores post exercise treatment (within groups comparison, p<0.05). Between groups comparison found a small but significant improvement in the Berg Balance Score (mean improvement 1.9 and 2 points, p <0.05) and 10-metre Walk Test (mean improvement of 0.09 and 0.11m/s, p <0.05) in the real tDCS group compared to the sham group after six weeks of training and at six months follow-up, respectively. There was no benefit in fatigue, falls and QOL scores in the real stimulation group compared to the control group.

CONCLUSION

Our results suggest that the addition of tDCS prior to exercise treatment provides a significant improvement in walking speed and balance in people with MS which lasts longer, compared to exercise alone. Further study is needed to optimize the use of this relatively inexpensive and well tolerated device for rehabilitation.

TRIAL REGISTRATION

Australia and New Zealand Clinical Trial Registry (ACTRN12628001836224).

Harnessing Brainwave Entrainment: A Non-invasive Strategy To Alleviate Neurological Disorder Symptoms

From 1990-2019, the burden of neurological disorders varied considerably across countries and regions. Psychiatric disorders, often emerging in early to mid-adulthood, are linked to late-life neurodegenerative diseases like Alzheimer's disease and Parkinson's disease. Individuals with conditions such as Major Depressive Disorder, Anxiety Disorder, Schizophrenia, and Bipolar Disorder face up to four times higher risk of developing neurodegenerative disorders. Contrarily, 65 % of those with neurodegenerative conditions experience severe psychiatric symptoms during their illness. Further, the limitation of medical resources continues to make this burden a significant global and local challenge. Therefore, brainwave entrainment provides therapeutic avenues for improving the symptoms of diseases. Brainwaves are rhythmic oscillations produced either spontaneously or in response to stimuli. Key brainwave patterns include gamma, beta, alpha, theta, and delta waves, yet the underlying physiological mechanisms and the brain's ability to shift between these dynamic states remain areas for further exploration. In neurological disorders, brainwaves are often disrupted, a phenomenon termed "oscillopathy". However, distinguishing these impaired oscillations from the natural variability in brainwave activity across different regions and functional states poses significant challenges. Brainwave-mediated therapeutics represents a promising research field aimed at correcting dysfunctional oscillations. Herein, we discuss a range of non-invasive techniques such as non-invasive brain stimulation (NIBS), neurologic music therapy (NMT), gamma stimulation, and somatosensory interventions using light, sound, and visual stimuli. These approaches, with their minimal side effects and cost-effectiveness, offer potential therapeutic benefits. When integrated, they may not only help in delaying disease progression but also contribute to the development of innovative medical devices for neurological care.

Effects of non-pharmacological interventions on gait and balance of persons with Multiple Sclerosis: A narrative review

BACKGROUND

Multiple Sclerosis (MS) is among the most common reasons for disability in young adults. Mobility impairment, primarily related to gait and balance, is ranked as the preeminent concern among persons with MS (PwMS). Gait and balance dysfunction can directly affect the quality of life and activities of daily life in PwMS, hence the importance of effective treatment strategies. Previous studies have demonstrated the positive effect of various non-pharmacological rehabilitation methods, including physiotherapy and electrical stimulation, on gait and mobility in PwMS. Non-pharmacological methods can be tailored to the individual needs and abilities of each patient, allowing healthcare providers to create personalized training programs. Furthermore, these methods typically result in minimal or no side effects.

PURPOSE

This review provides a comprehensive overview of an array of non-pharmacological treatment approaches aimed at enhancing ambulatory performance in PwMS.

METHODS

We performed a narrative review of the original papers available in PubMed, investigating the effects of different nonmedical approaches on the gait and balance performance of the PwMS. Reviewed treatment approaches include "exercise, physical rehabilitation, dual-task (DT) rehabilitation, robot-assisted rehabilitation, virtual reality-assisted rehabilitation, game training, electrical stimulation devices, auditory stimulation, visual feedback, and shoe insoles".

RESULTS AND CONCLUSIONS

Eighty articles were meticulously reviewed. Our study highlights the positive effects of non-pharmacological interventions on patients' quality of life, reducing disability, fatigue, and muscle spasticity. While some methods, including exercise and physiotherapy, showed substantial promise, further research is needed to evaluate whether visual biofeedback and auditory stimulation are preferable over conventional approaches. Additionally, approaches such as functional electrical stimulation, non-invasive brain stimulation, and shoe insoles demonstrate substantial short-term benefits, prompting further investigation into their long-term effects. Non-pharmacological interventions can serve as a valuable complement to medication-based approaches.

Does non-invasive brain stimulation improve spatiotemporal gait parameters in people with multiple sclerosis? A systematic review and meta-analysis

BACKGROUND

Multiple sclerosis (MS) is a chronic autoimmune disease that causes progressive functional impairment, mainly in walking tasks. Noninvasive brain stimulation (NIBS) could influence the motor function and improving gait ability of patients.

OBJECTIVE

The aim was to analyze the effects of NIBS (transcranial direct current stimulation [tDCS] or transcranial magnetic stimulation [TMS] on functional locomotion in people with multiple sclerosis (PwMS).

METHODS

A search was conducted for randomized controlled trials published up to November 2023 comparing the application of NIBS versus a sham or control group. The primary outcome were spatiotemporal gait parameters and functional mobility. Two review authors independently assessed the risk of bias in the included studies, and we used the Grading of Recommendations Assessment, Development, and Evaluation methodology to rate the certainty of the evidence for each outcome. A meta-analysis was performed by pooling the appropriate data using RevMan Web.

RESULTS

A total of four clinical trials were included for metanalysis. We observed that there is no statistically significant difference in overall effect in gait speed (MD = 0.08; 95% CI: -0.08-0.24; p = 0.32), and cadence (MD = 0.22; 95% CI: -11.54-11.98; p = 0.97%) between groups. But there was a statistically significant difference in overall effect in stride length between groups (MD:0.19; 95% CI: 0.07-0.31; p = 0.002), mainly when the intervention performed by multiple sessions and associated with motor rehabilitation (MD = 0.29; 95% CI: 0.14-0.44; p = 0.0002).

CONCLUSIONS

tDCS applied by multiple session and combined with motor rehabilitation (i.e., aerobic and/or resistance training) can improve stride length in PwMS.

The effect of multi-function swing suspension training on upper and lower extremities function and quality of life in multiple sclerosis women with different disability status

BACKGROUND

Multiple sclerosis (MS) can lead to impaired upper and lower extremity function (ULEF), which reduces the quality of life (QoL). Exercise is beneficial for symptom management, but newer approaches like multi-function swing suspension training (MFSST) need further investigation. Additionally, tailoring exercises to individual needs remains a challenging area of investigation.

AIM

To investigate the effect of an MFSST program on ULEF, and QoL in MS women according to the expanded disability status scale (EDSS) score.

METHODS

Forty-seven MS women meeting selection criteria were randomly assigned to intervention groups A (EDSS 2-4) and B (EDSS 4.5-6.5), and the control group (EDSS 2-6.5). Intervention groups did an 8-week MFSST program with 3 × 1hr sessions/week. Prior to the intervention, and after 4, 6, and 8 weeks, the 9-hole peg test (9HPT) and the timed 25-foot walk (T25FW) test were performed for both the intervention groups and the control group. The Short Form questionnaire (SF-36) was used to measure their QoL.

RESULTS

Significant main effects for time were observed in both the 9HPT (F = 52.48, p = 0.001, Pη2 = 0.78) and the T25FW (F = 85.63, p = 0.000, Pη2 = 0.859). Speed increased between the pre-test, 4th week, 6th week, and 8th week in both tests. These tests revealed significant interaction effects between group and time. The 9HPT had an F-value of 9.01 (p = 0.001, Pη2 = 0.392), while the T25FW had an F-value of 13.812 (p = 0.000, Pη2 = 0.497). Across both tests, Group B, with higher EDSS scores, demonstrated greater speed improvement over the three-time measurements (4th week, 6th week, and 8th week) than Group A. The control group did not exhibit any improvement in speed. Intervention groups showed improvement in all QoL subscales except emotional role limitation.

CONCLUSIONS

An 8-week MFSST improves ULEF and QoL in women with MS, particularly those with higher EDSS scores (more than 4.5). Notably, significant improvements were observed after four weeks of the intervention. The incorporation of a variety of exercises in a single device provides a significant advantage over traditional exercise programs. Therefore, MFSST can be a valuable and efficient tool for improving symptoms and QoL in MS patients.

TRIAL REGISTRATION

IRCT20220526054997N1.

Effectiveness of transcranial direct current stimulation on balance and gait in patients with multiple sclerosis: systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Motor impairments are very common in neurological diseases such as multiple sclerosis. Noninvasive brain stimulation could influence the motor function of patients.

OBJECTIVE

The aim of this meta-analysis was to evaluate the effectiveness of transcranial direct current stimulation (tDCS) on balance and gait ability in patients with multiple sclerosis. Additionally, a secondary aim was to compare the influence of the stimulation location of tDCS on current effectiveness.

METHODS

A search was conducted for randomized controlled trials published up to May 2023 comparing the application of tDCS versus a sham or control group. The primary outcome variables were balance and gait ability.

RESULTS

Eleven studies were included in the qualitative analysis, and ten were included in the quantitative analysis, which included 230 patients with multiple sclerosis. The average effect of tDCS on gait functionality was superior to that of the control group (SMD = -0.71; 95% CI, -1.05 to -0.37). However, the overall results of the tDCS vs. sham effect on static balance did not show significant differences between groups (MD = 1.26, 95% CI, -1.31 to 3.82). No significant differences were found when different locations of tDCS were compared.

CONCLUSIONS

These results reveal that tDCS is an effective treatment for improving gait ability with a low quality of evidence. However, the application of tDCS has no effect on static balance in patients with multiple sclerosis with very low quality of evidence. Similarly, there seems to be no difference regarding the stimulation area with tDCS.

Non-invasive brain stimulation on clinical symptoms in multiple sclerosis patients: A systematic review and meta-analysis

BACKGROUND

Non-invasive brain stimulation (NIBS) has demonstrated mixed effects on the clinical symptoms of multiple sclerosis. This systematic review and meta-analysis aimed to evaluate the effects of NIBS techniques on the most common symptoms of MS.

METHODS

A literature search was performed until October 2022 which included randomized controlled trials and quasi-experimental studies that used sham-controlled NIBS in patients with MS. We calculated the Hedge's effect sizes of each domain of interest and their 95% confidence intervals (95% CIs) and performed random effects meta-analyses.

RESULTS

A total of 49 studies were included in the systematic review (944 participants). Forty-four eligible studies were included for quantitative analysis, of which 33 applied transcranial direct current stimulation (tDCS), 9 transcranial magnetic stimulation (TMS), and 2 transcranial random noise stimulation (tRNS). We found a significant decrease in fatigue (ES:  - 0.86, 95% CI:  - 1.22 to - 0.51, p < 0.0001), pain (ES: - 1.91, 95% CI, - 3.64 to - 0.19, p=  0.03) and psychiatric symptoms (ES: - 1.44, 95% CI - 2.56 to - 0.32, p = 0.01) in favor of tDCS compared with the sham. On the other hand, there was no strong evidence showing tDCS effectiveness on motor performance and cognition (ES: - 0.03, 95% CI - 0.35 to 0.28, p = 0.83 and ES: 0.71, 95% CI, - 0.09 to 1.52, p = 0.08, respectively). Regarding TMS, we found a significant decrease in fatigue (ES: - 0.45, 95% CI: - 0.84 to -0.07, p = 0.02) and spasticity levels (ES: - 1.11, 95% CI: - 1.48 to - 0.75, p < 0.00001) compared to the sham. However, there was no strong evidence of the effectiveness of TMS on motor performance (ES: - 0.39, 95% CI - 0.95 to 0.16, p = 0.16). Finally, there was no significant evidence showing the effectiveness of tRNS on fatigue levels (ES: - 0.28, 95% CI: - 1.02 to 0.47, p = 0.46) and cognitive improvement (ES: - 0.04, 95% CI: - 0.6, 0.52, p = 0.88) compared with the sham.

CONCLUSIONS

Overall, most studies have investigated the effects of tDCS on MS symptoms, particularly fatigue. The symptom that most benefited from NIBS was fatigue, while the least to benefit was motor performance. In addition, we found that disability score was associated with fatigue improvement. Thus, these findings support the idea that NIBS could have some promising effects on specific MS symptoms. It is also important to underscore that studies are very heterogeneous regarding the parameters of stimulation, and this may also have influenced the effects on some specific behavioral domains.

Influence of Transcranial Direct Current Stimulation and Exercise on Physical Capacity and Gait in Multiple Sclerosis: A Cross-Over Pilot Study

Physical capacity provides a link between disease or impairment and limitations in activity; in multiple sclerosis (MS), it is limited and decreased. The aim of this study was to study the effects of exercise and transcranial direct current stimulation (tDCS) on the left dorsolateral prefrontal cortex area in MS patients with fatigue and an impaired gait ability. A cross-over design was carried out on fifteen patients with two disability associations, but three were excluded. Before and after each intervention, the 6 min walk test (6MWT) and the 2 min walk test (2MWT) were used to assess walking ability and the Modified Fatigue Impact Scale (MFIS) was used to assess fatigue. A total of twelve patients were enrolled (48.0 median age, Kurtzke Disability Scale (EDSS) 3.66 ± 1.3): five females and seven males. After the application of the exercise program, significant improvements were observed in the 6MWT (p < 0.001, g = 0.159) and 2MWT (p < 0.001, g = 0.182). Furthermore, fatigue was significantly reduced after the application of the exercise program (p < 0.05, g = 0.742) and after tDCS (p < 0.05, g = 0.525). We could consider therapeutic exercise in the future to improve the walking ability and fatigue in MS patients. Furthermore, tDCS did not exert a significant improvement in walking ability, but it appeared to influence fatigue. Clinical trial registration code: ACTRN12622000264785.

Efficacy of non-invasive brain stimulation on cognitive and motor functions in multiple sclerosis: A systematic review and meta-analysis

Objective

In this study, we aimed to investigate the effects of non-invasive brain stimulation (NIBS) on cognitive and motor functions in patients with multiple sclerosis (pwMS).

Methods

A literature search was performed in the Cochrane Library, Embase, PubMed, Web of Science, Medline, CNKI, and Wan fang. The time interval used for database construction was up to December 2022, and the language was not limited. The collected trials were subsequently screened, the data were extracted, the quality was evaluated, and the effect sizes were computed using STATA/MP Version 13 for outcome analysis. Standard mean difference (SMD) and 95% confidence interval (CI) were calculated for domain of interest.

Results

In total, 17 articles that examined 364 patients with multiple sclerosis were included in this analysis. Non-invasive brain stimulation did not improve the overall cognitive function [SMD = 0.18, 95% CI (-0.32, 0.69), P = 0.475] but helped improve motor function in patients [SMD = 0.52, 95% CI (0.19, 0.85), P = 0.002]. Moreover, this study specifically indicated that non-invasive brain stimulation improved alerting [SMD = 0.68, 95% CI (0.09, 1.26), P = 0.02], whereas non-invasive brain stimulation intervention improved motor function in patients aged <45 years [SMD = 0.67, 95% CI (0.23, 1.10), P = 0.003] and in patients with expanded disability status scale scores (EDSS) <3.5 [SMD = 0.82, 95% CI (0.22, 1.42), P = 0.007]. In particular, NIBS contributed to the improvement of spasticity in pwMS [SMD = 0.68, 95% CI (0.13, 1.23), P = 0.015].

Conclusion

These results of this present study provide evidence that non-invasive brain stimulation could improve alertness in pwMS. Furthermore, NIBS may help pwMS with motor function and those who are under 45 years of age or with EDSS < 3.5 improve their motor function. For the therapeutic use of NIBS, we recommend applying transcranial magnetic stimulation as an intervention and located on the motor cortex M1 according to the subgroup analysis of motor function. These findings warrant verification.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022301012.

The Effect of Combining Transcranial Direct Current Stimulation Treatment and an Exercise Program on Fragility in a Population with Multiple Sclerosis: Cross-Over Design Trial

BACKGROUND

The relationship between fragility and neurological diseases is extensive and affects many patients with multiple sclerosis (MS), whose risk factors are related to fragility.

OBJECTIVE

To study the effects of exercise and transcranial direct current stimulation (tDCS) in MS patients with fatigue from four dimensions: functional mobility, balance, fatigue, and depression.

METHODS

A total of 12 patients who belonged to two associations of people with physical disabilities participated. Functional mobility, depression, balance, and fatigue were assessed before and after the intervention. Transcranial direct current stimulation and the exercise program were carried out over a 4-week period with a wash-out period of 5 months.

RESULTS

After the application of tDCS, we found significant improvements in balance (p < 0.05, g = 0.632), depression (p < 0.05, g = 0.402), functional mobility (p < 0.05, g = 0.297), and fatigue (p < 0.05, g = 0.526). After the exercise program, significant improvements were shown in balance (p < 0.01, g = 0.418), depression (p < 0.001, g = 0.540), functional mobility (p < 0.01, g = 0.262), and fatigue (p < 0.01, g = 0.742). Two-way mixed-measures ANOVA showed that all variables improved in both groups, with significant differences over time but not between groups. Secondary analysis showed significant correlations between balance and functional mobility (r = 0.671, p = 0.017), depression and fatigue (r = 0.586, p = 0.044) and between intensity of rehabilitation and balance (r = 0.622, p = 0.031).

CONCLUSION

Participating in an exercise program and receiving tDCS separately improved the variables of depression, balance, mobility, and fatigue.

Effects of Nonconsecutive Sessions of Transcranial Direct Current Stimulation and Stationary Cycling on Walking Capacity in Individuals With Multiple Sclerosis

BACKGROUND

Exercise has been demonstrated to be safe and well-tolerated in individuals with multiple sclerosis (MS). Physical activity has been shown to enhance the therapeutic effects of transcranial direct current stimulation (tDCS). This study aimed to determine the efficacy of intermittent tDCS combined with riding a stationary bicycle to improve walking capacity in individuals with MS.

METHODS

This double-blind randomized controlled trial enrolled 50 eligible participants. Thirty-nine participants completed the study: 21 in the active group and 18 in the control group. Participants were assigned randomly to exercise on a stationary bike in conjunction with anodal tDCS or to exercise combined with a sham tDCS protocol. Walking capacity tests (2-Minute Walk Test, 5-Meter Walk Test, Timed Up and Go test), manual muscle testing, the Fatigue Severity Scale, and the Multiple Sclerosis Quality of Life-54 were used to determine outcomes.

RESULTS

In terms of observed changes in 2-Minute Walk Test and 5-Meter Walk Test values, the exercise + tDCS group achieved significantly higher posttreatment values than the exercise + sham tDCS group. After the intervention and 1 month later, the intervention group's mean Timed Up and Go test value decreased significantly (P = .002) compared with that of the control group. There was no difference in Fatigue Severity Scale score, Multiple Sclerosis Quality of Life-54 score, or manual muscle testing improvement between the 2 groups.

CONCLUSIONS

Nonconsecutive sessions of anodal tDCS combined with stationary cycling may have a greater effect on the walking capacity of individuals with MS than exercise alone.

Potential of Transcranial Direct Current Stimulation in Alzheimer's Disease: Optimizing Trials Toward Clinical Use

Transcranial direct current stimulation (tDCS) is a safe and well-tolerated noninvasive method for stimulating the brain that is rapidly developing into a treatment method for various neurological and psychiatric conditions. In particular, there is growing evidence of a therapeutic role for tDCS in ameliorating or delaying the cognitive decline in Alzheimer's disease (AD). We provide a brief overview of the current development and application status of tDCS as a nonpharmacological therapeutic method for AD and mild cognitive impairment (MCI), summarize the levels of evidence, and identify the improvements needed for clinical applications. We also suggest future directions for large-scale controlled clinical trials of tDCS in AD and MCI, and emphasize the necessity of identifying the mechanistic targets to facilitate clinical applications.

Efficacy of Transcranial Direct Current Stimulation (tDCS) on Balance and Gait in Multiple Sclerosis Patients: A Machine Learning Approach

Transcranial direct current stimulation (tDCS) has emerged as an appealing rehabilitative approach to improve brain function, with promising data on gait and balance in people with multiple sclerosis (MS). However, single variable weights have not yet been adequately assessed. Hence, the aim of this pilot randomized controlled trial was to evaluate the tDCS effects on balance and gait in patients with MS through a machine learning approach. In this pilot randomized controlled trial (RCT), we included people with relapsing−remitting MS and an Expanded Disability Status Scale >1 and <5 that were randomly allocated to two groups—a study group, undergoing a 10-session anodal motor cortex tDCS, and a control group, undergoing a sham treatment. Both groups underwent a specific balance and gait rehabilitative program. We assessed as outcome measures the Berg Balance Scale (BBS), Fall Risk Index and timed up-and-go and 6-min-walking tests at baseline (T0), the end of intervention (T1) and 4 (T2) and 6 weeks after the intervention (T3) with an inertial motion unit. At each time point, we performed a multiple factor analysis through a machine learning approach to allow the analysis of the influence of the balance and gait variables, grouping the participants based on the results. Seventeen MS patients (aged 40.6 ± 14.4 years), 9 in the study group and 8 in the sham group, were included. We reported a significant repeated measures difference between groups for distances covered (6MWT (meters), p < 0.03). At T1, we showed a significant increase in distance (m) with a mean difference (MD) of 37.0 [−59.0, 17.0] (p = 0.003), and in BBS with a MD of 2.0 [−4.0, 3.0] (p = 0.03). At T2, these improvements did not seem to be significantly maintained; however, considering the machine learning analysis, the Silhouette Index of 0.34, with a low cluster overlap trend, confirmed the possible short-term effects (T2), even at 6 weeks. Therefore, this pilot RCT showed that tDCS may provide non-sustained improvements in gait and balance in MS patients. In this scenario, machine learning could suggest evidence of prolonged beneficial effects.

Split-Belt Training but Not Cerebellar Anodal tDCS Improves Stability Control and Reduces Risk of Fall in Patients with Multiple Sclerosis

The objective of this study was to examine the therapeutic potential of multiple sessions of training on a split-belt treadmill (SBT) combined with cerebellar anodal transcranial direct current stimulation (tDCS) on gait and balance in People with Multiple Sclerosis (PwMS). Twenty-two PwMS received six sessions of anodal (PwMS_real, n = 12) or sham (PwMS_sham, n = 10) tDCS to the cerebellum prior to performing the locomotor adaptation task on the SBT. To evaluate the effect of the intervention, functional gait assessment (FGA) scores and distance walked in 2 min (2MWT) were measured at the baseline (T0), day 6 (T5), and at the 4-week follow up (T6). Locomotor performance and changes of motor outcomes were similar in PwMS_real and PwMS_sham independently from tDCS mode applied to the cerebellum (anodal vs. sham, on FGA, p = 0.23; and 2MWT, p = 0.49). When the data were pooled across the groups to investigate the effects of multiple sessions of SBT training alone, significant improvement of gait and balance was found on T5 and T6, respectively, relative to baseline (FGA, p < 0.001 for both time points). The FGA change at T6 was significantly higher than at T5 (p = 0.01) underlining a long-lasting improvement. An improvement of the distance walked during the 2MWT was also observed on T5 and T6 relative to T0 (p = 0.002). Multiple sessions of SBT training resulted in a lasting improvement of gait stability and endurance, thus potentially reducing the risk of fall as measured by FGA and 2MWT. Application of cerebellar tDCS during SBT walking had no additional effect on locomotor outcomes.

Efficacy of transcranial direct current stimulation in people with multiple sclerosis: a review

BACKGROUND AND PURPOSE

Multiple sclerosis (MS) is a chronic inflammatory disease causing a wide range of symptoms including motor and cognitive impairment, fatigue and pain. Over the last two decades, non-invasive brain stimulation, especially transcranial direct current stimulation (tDCS), has increasingly been used to modulate brain function in various physiological and pathological conditions. However, its experimental applications for people with MS were noted only as recently as 2010 and have been growing since then. The efficacy for use in people with MS remains questionable with the results of existing studies being largely conflicting. Hence, the aim of this review is to paint a picture of the current state of tDCS in MS research grounded on studies applying tDCS that have been done to date.

METHODS

A keyword search was performed to retrieve articles from the earliest article identified until 14 February 2021 using a combination of the groups (1) 'multiple sclerosis', 'MS' and 'encephalomyelitis' and (2) 'tDCS' and 'transcranial direct current stimulation'.

RESULTS

The analysis of the 30 articles included in this review underlined inconsistent effects of tDCS on the motor symptoms of MS based on small sample sizes. However, tDCS showed promising benefits in ameliorating fatigue, pain and cognitive symptoms.

CONCLUSION

Transcranial direct current stimulation is attractive as a non-drug approach in ameliorating MS symptoms, where other treatment options remain limited. The development of protocols tailored to the individual's own neuroanatomy using high definition tDCS and the introduction of network mapping in the experimental designs might help to overcome the variability between studies.

Cerebellar Contributions to Motor Impairments in People with Multiple Sclerosis

Although Charcot characterized classic cerebellar symptoms in people with multiple sclerosis (PwMS) in 1877, the impact of cerebellar dysfunction on MS symptoms has predominately been evaluated in the last two decades. Recent studies have clearly demonstrated the association between cerebellar pathology, including atrophy and reduced fractional anisotropy in the peduncles, and motor impairments, such as reduced gait velocity and time to complete walking tasks. However, future studies using novel imaging techniques are needed to elucidate all potential pathophysiology that is associated with disability in PwMS. Additionally, future studies are required to determine the most effective treatments for motor impairments in PwMS, including the specific type and duration of exercise interventions, and potential means to amplify their effects, such as transcranial direct current stimulation (tDCS). This mini-review critically discusses the distinct role of cerebellar dysfunction in motor impairments in PwMS, potential treatments, and directions for future studies.

Alterations in Leg Muscle Glucose Uptake and Inter-Limb Asymmetry after a Single Session of tDCS in Four People with Multiple Sclerosis

Asymmetrical lower limb weakness is an early symptom and significant contributor to the progressive worsening of walking ability in people with multiple sclerosis (PwMS). Transcranial direct current stimulation (tDCS) may effectively increase neural drive to the more-affected lower limb and, therefore, increase symmetrical activation. Four PwMS (1 female, age range: 27–57) underwent one session each of 3 mA or SHAM tDCS over the motor cortex corresponding to their more-affected limb followed by 20 min of treadmill walking at a self-selected speed. Two min into the treadmill task, the subjects were injected with the glucose analog [¹⁸F]fluorodeoxyglucose (FDG). Immediately after treadmill walking, the subjects underwent whole-body positron emission tomography (PET) imaging. Glucose uptake (GU) values were compared between the legs, the spatial distribution of FDG was assessed to estimate glucose uptake heterogeneity (GUh), and GU asymmetry indices (AIs) were calculated. After tDCS, GU was altered, and GUh was decreased in various muscle groups in each subject. Additionally, AIs went from asymmetric to symmetric after tDCS in the subjects that demonstrated asymmetrical glucose uptake during SHAM. These results indicate that tDCS improved GU asymmetries, potentially from an increased neural drive and a more efficient muscle activation strategy of the lower limb in PwMS.

Non-invasive brain stimulation to assess neurophysiologic underpinnings of lower limb motor impairment in multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a neuroinflammatory disease resulting in axonal demyelination and an amalgamation of symptoms which commonly result in decreased quality of life due to mobility dysfunction and limited participation in meaningful activities.

NEW METHOD

The use of non-invasive brain stimulation (NIBS) techniques, specifically transcranial magnetic and transcranial direct current stimulation, have been essential in understanding the pathophysiological decrements related to disease progression, particularly with regard to motor impairments. Although the research in this area has primarily focused on the upper extremities, new interest has arisen in understanding the neurophysiological underpinnings of lower limb impairment. Therefore, the purpose of this review is to: first, provide an overview of common NIBS techniques used to explore sensorimotor neurophysiology; second, summarize lower limb neuromuscular and mobility impairments typically observed in PwMS; third, review the current knowledge regarding interactions between TMS-assessed neurophysiology and lower limb impairments in PwMS; and fourth, provide recommendations for future NIBS studies based on current gaps in the literature.

RESULTS

PwMS exhibit reduced excitability and increased inhibitory neurophysiologic function which has been related to disease severity and lower limb motor impairments. Comparison with existing methods: Moreover, promising results indicate that the use of repetitive stimulation and transcranial direct current stimulation may prime neural adaptability and prove useful as a therapeutic tool in ameliorating lower limb impairments.

CONCLUSIONS

While these studies are both informative and promising, additional studies are necessary to be conclusive. As such, studies assessing objective measures of lower limb impairments associated with neurophysiological adaptations need further evaluation.

Update on the Use of Transcranial Electrical Brain Stimulation to Manage Acute and Chronic COVID-19 Symptoms

The coronavirus disease 19 (COVID-19) pandemic has resulted in the urgent need to develop and deploy treatment approaches that can minimize mortality and morbidity. As infection, resulting illness, and the often prolonged recovery period continue to be characterized, therapeutic roles for transcranial electrical stimulation (tES) have emerged as promising non-pharmacological interventions. tES techniques have established therapeutic potential for managing a range of conditions relevant to COVID-19 illness and recovery, and may further be relevant for the general management of increased mental health problems during this time. Furthermore, these tES techniques can be inexpensive, portable, and allow for trained self-administration. Here, we summarize the rationale for using tES techniques, specifically transcranial Direct Current Stimulation (tDCS), across the COVID-19 clinical course, and index ongoing efforts to evaluate the inclusion of tES optimal clinical care.

Walking in multiple sclerosis improves with tDCS: a randomized, double-blind, sham-controlled study

OBJECTIVE

To evaluate whether multiple sessions of transcranial direct current stimulation (tDCS) applied to the primary motor (M1) cortex paired with aerobic exercise can improve walking functions in multiple sclerosis (MS).

METHODS

MS participants were recruited for a double-blind, parallel-arm, randomized, sham-controlled trial and assigned to 10 sessions (5 d/wk for 2 weeks) of either active or sham tDCS paired with unloaded cycling for 20 minutes. Stimulation was administered over the left M1 cortex (2.5 mA; anode over C3/cathode over FP2). Gait spatiotemporal parameters were assessed using a wearable inertial sensor (10-meter and 2-minute walking tests). Measurements were collected at baseline, end of tDCS intervention, and 4-week postintervention to test for duration of any benefits.

RESULTS

A total of 15 participants completed the study, nine in the active and six in the sham condition. The active and sham groups were matched according to gender (50% vs. 40% female), neurologic disability (median EDSS 5.5 vs. 5), and age (mean 52.1 ± 12.9 vs. 53.7 ± 9.8 years). The active group had a significantly greater increase in gait speed (0.87 vs. 1.20 m/s, p < 0.001) and distance covered during the 2-minute walking test (118.53 vs. 133.06 m, p < 0.001) at intervention end compared to baseline. At 4-week follow-up, these improvements were maintained (baseline vs. follow-up: gait speed 0.87 vs. 1.18 m/s, p < 0.001; distance traveled 118.53 vs. 143.82 m, p < 0.001).

INTERPRETATION

Multiple sessions of tDCS paired with aerobic exercise lead to cumulative and persisting improvements in walking and endurance in patients with MS.

Different Effects of Transcranial Direct Current Stimulation on Leg Muscle Glucose Uptake Asymmetry in Two Women with Multiple Sclerosis

Asymmetrical lower limb strength is a significant contributor to impaired walking abilities in people with multiple sclerosis (PwMS). Transcranial direct current stimulation (tDCS) may be an effective technique to enhance cortical excitability and increase neural drive to more-affected lower limbs. A sham-controlled, randomized, cross-over design was employed. Two women with MS underwent two 20 min sessions of either 3 mA tDCS or Sham before 20 min of treadmill walking at a self-selected speed. During walking, the participants were injected with the glucose analogue, [¹⁸F] fluorodeoxyglucose (FDG). Participants were then imaged to examine glucose metabolism and uptake asymmetries in the legs. Standardized uptake values (SUVs) were compared between the legs and asymmetry indices were calculated. Subject 2 was considered physically active (self-reported participating in at least 30 min of moderate-intensity physical activity on at least three days of the week for the last three months), while Subject 1 was physically inactive. In Subject 1, there was a decrease in SUVs at the left knee flexors, left upper leg, left and right plantar flexors, and left and right lower legs and SUVs in the knee extensors and dorsiflexors were considered symmetric after tDCS compared to Sham. Subject 2 showed an increase in SUVs at the left and right upper legs, right plantar flexors, and right lower leg with no muscle group changing asymmetry status. This study demonstrates that tDCS may increase neural drive to leg muscles and decrease glucose uptake during walking in PwMS with low physical activity levels.