Prefrontal tDCS Decreases Pain in Patients with Multiple Sclerosis

Comparative Neurological and Behavioral Assessment of Central and Peripheral Stimulation Technologies for Induced Pain and Cognitive Tasks

Pain is a multifaceted, multisystem disorder that adversely affects neuro-psychological processes. This study compares the effectiveness of central stimulation (transcranial direct current stimulation-tDCS over F3/F4) and peripheral stimulation (transcutaneous electrical nerve stimulation-TENS over the median nerve) in pain inhibition during a cognitive task in healthy volunteers and to observe potential neuro-cognitive improvements. Eighty healthy participants underwent a comprehensive experimental protocol, including cognitive assessments, the Cold Pressor Test (CPT) for pain induction, and tDCS/TENS administration. EEG recordings were conducted pre- and post-intervention across all conditions. The protocol for this study was categorized into four groups: G1 (control), G2 (TENS), G3 (anodal-tDCS), and G4 (cathodal-tDCS). Paired t-tests (p < 0.05) were conducted to compare Pre-Stage, Post-Stage, and neuromodulation conditions, with t-values providing insights into effect magnitudes. The result showed a reduction in pain intensity with TENS (p = 0.002, t-value = -5.34) and cathodal-tDCS (p = 0.023, t-value = -5.08) and increased pain tolerance with TENS (p = 0.009, t-value = 4.98) and cathodal-tDCS (p = 0.001, t-value = 5.78). Anodal-tDCS (p = 0.041, t-value = 4.86) improved cognitive performance. The EEG analysis revealed distinct neural oscillatory patterns across the groups. Specifically, G2 and G4 showed delta-power reductions, while G3 observed an increase. Moreover, G2 exhibited increased theta-power in the occipital region during CPT and Post-Stages. In the alpha-band, G2, G3, and G4 had reductions Post-Stage, while G1 and G3 increased. Additionally, beta-power increased in the frontal region for G2 and G3, contrasting with a reduction in G4. Furthermore, gamma-power globally increased during CPT1, with G1, G2, and G3 showing reductions Post-Stage, while G4 displayed a global decrease. The findings confirm the efficacy of TENS and tDCS as possible non-drug therapeutic alternatives for cognition with alleviation from pain.

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.

Pharmacological and Non-pharmacological Approaches for the Management of Neuropathic Pain in Multiple Sclerosis

Multiple sclerosis is a chronic inflammatory disease that affects the central nervous system and can cause various types of pain including ongoing extremity pain, Lhermitte's phenomenon, trigeminal neuralgia, and mixed pain. Neuropathic pain is a major concern for individuals with multiple sclerosis as it is directly linked to myelin damage in the central nervous system and the management of neuropathic pain in multiple sclerosis is challenging as the options available have limited efficacy and can cause unpleasant side effects. The literature search was conducted across two databases, PubMed, and Google Scholar. Eligible studies included clinical trials, observational studies, meta-analyses, systematic reviews, and narrative reviews. The objective of this article is to provide an overview of literature on pharmacological and non-pharmacological strategies employed in the management of neuropathic pain in multiple sclerosis. Pharmacological options include cannabinoids, muscle relaxants (tizanidine, baclofen, dantrolene), anticonvulsants (benzodiazepines, gabapentin, phenytoin, carbamazepine, lamotrigine), antidepressants (duloxetine, venlafaxine, tricyclic antidepressants), opioids (naltrexone), and botulinum toxin variants, which have evidence from various clinical trials. Non-pharmacological approaches for trigeminal neuralgia may include neurosurgical methods. Non-invasive methods, physical therapy, and psychotherapy (cognitive behavioral therapy, acceptance and commitment therapy and mindfulness-based stress reduction) may be recommended for patients with neuropathic pain in multiple sclerosis. The choice of treatment depends on the severity and type of pain as well as other factors, such as patient preferences and comorbidities. There is a pressing need for healthcare professionals and researchers to prioritize the development of better strategies for managing multiple sclerosis-induced neuropathic pain.

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.

Brain stimulation targets for chronic pain: Insights from meta-analysis, functional connectivity and literature review

Noninvasive brain stimulation (NIBS) techniques have demonstrated their potential for chronic pain management, yet their efficacy exhibits variability across studies. Refining stimulation targets and exploring additional targets offer a possible solution to this challenge. This study aimed to identify potential brain surface targets for NIBS in treating chronic pain disorders by integrating literature review, neuroimaging meta-analysis, and functional connectivity analysis on 90 chronic low back pain patients. Our results showed that the primary motor cortex (M1) (C3/C4, 10-20 EEG system) and prefrontal cortex (F3/F4/Fz) were the most used brain stimulation targets for chronic pain treatment according to the literature review. The bilateral precentral gyrus (M1), supplementary motor area, Rolandic operculum, and temporoparietal junction, were all identified as common potential NIBS targets through both a meta-analysis sourced from Neurosynth and functional connectivity analysis. This study presents a comprehensive summary of the current literature and refines the existing NIBS targets through a combination of imaging meta-analysis and functional connectivity analysis for chronic pain conditions. The derived coordinates (with integration of the international electroencephalography (EEG) 10/20 electrode placement system) within the above brain regions may further facilitate the localization of these targets for NIBS application. Our findings may have the potential to expand NIBS target selection beyond current clinical trials and improve chronic pain treatment.

Short-term effectiveness of transcranial direct current stimulation in the nociceptive behavior of neuropathic pain rats in development

Neuropathic pain (NP) is caused by a lesion that triggers pain chronification and central sensitization and it can develop in a different manner, dependent of age. Recent studies have demonstrated the efficacy of transcranial direct current stimulation (tDCS) for treating NP. Then, we aimed to investigate the effects of tDCS and BDNF levels in neuropathic pain rats in development, with 30 days old in the beginning of experiments. Eight-five male Wistar rats were subjected to chronic constriction injury. After establishment of NP, bimodal tDCS was applied to the rats for eight consecutive days, for 20 minutes each session. Subsequently, nociceptive behavior was assessed at baseline, 14 days after surgery, 1 day and 7 days after the end of tDCS. The rats were sacrificed 8 days after the last session of tDCS. An increase in the nociceptive threshold was observed in rats in development 1 day after the end of tDCS (short-term effect), but this effect was not maintained 7 days after the end of tDCS (long-term effect). Furthermore, brain derived neurotrophic factor (BDNF) levels were analyzed in the frontal cortex, spinal cord and serum using ELISA assays. The neuropathic pain model showed an effect of BDNF in the spinal cord of rats in development. There were no effects of BNDF levels of pain or tDCS in the frontal cortex or serum. In conclusion, tDCS is an effective technique to relieve nociceptive behavior at a short-term effect in neuropathic pain rats in development, and BDNF levels were not altered at long-term effect.

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).

Effects of transcranial alternating current stimulation on cognitive function in people with multiple sclerosis: A randomized controlled trial

BACKGROUND

Cognitive impairment is a core symptom that profoundly impacts the lives of people with multiple sclerosis (PwMS). Since the existing disease modifying therapies can only stabilize, but not actively treat, cognition in PwMS, there is an unmet need to expand approaches to treat these cognitive symptoms. Transcranial alternating current stimulation (tACS) permits frequency-specific entrainment of neural oscillations intrinsic to cognitive activity. However, the effects of the tACS on cognitive function in PwMS have not yet been assessed. We aimed to evaluate the potential efficacy of applying frontal theta-tACS to improve information processing speed in PwMS.

METHODS

60 PwMS with cognitive complaints were enrolled in a double-blinded, randomized, controlled trial with three stimulation groups: 2 mA, 1 mA, or sham control. A single session of theta-tACS was applied while participants were engaged in a cognitive program which has shown to improve processing speed in PwMS. tACS effects were examined by the Symbol Digit Modalities Test (SDMT). Tolerability, side effects and acceptability were measured.

RESULTS

1 mA groups had a significantly higher SDMT score after stimulation compared to their pre-stimulation score, 2 mA group showed a marginally significant improvement of their SDMT score, while the SDMT score in the sham group did not change. Overall, 49% of the stimulation group participants showed a clinically meaningful SDMT improvement (4+-point increase).

CONCLUSION

tACS is a well-tolerated, non-pharmacological intervention. Based on the positive effects observed in the current study of a single session of tACS applied during cognitive engagement, the effects of repeated tACS on cognitive function in PwMS merit further research.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04466228.

Home-Based Treatment for Chronic Pain Combining Neuromodulation, Computer-Assisted Training, and Telemonitoring in Patients With Breast Cancer: Protocol for a Rehabilitative Study

BACKGROUND

Chronic pain is a disabling symptom frequently reported in patients with breast cancer with a prevalence ranging from 25% to 60%, representing a major health issue. It has negative consequences on health status, causing psychological distress and affecting quality of life. Furthermore, the clinical management of chronic pain is often inadequate, and many patients do not benefit from the administration of pharmacological treatments. Alternative therapeutic options have been implemented to improve the psychophysical well-being of patients, including neuromodulation and complementary interventions.

OBJECTIVE

We aimed to investigate the effectiveness of a home care strategy combining computerized rehabilitation, transcranial direct current stimulation (tDCS), and remote telemonitoring via a web-based platform in patients with breast cancer suffering for chronic pain.

METHODS

A web-based structured survey aimed at monitoring chronic pain and its effect on psychological functions will be delivered to patients with breast cancer through social media and email. In total, 42 patients with breast cancer affected by chronic pain will be recruited during the medical screening visit. The patients will be randomly divided into 3 treatment groups that will carry out either tDCS only, exercise therapy only, or a combination of both over a 3-week period. All the treatments will be delivered at the patients' home through the use of a system including a tablet, wearable inertial sensors, and a tDCS programmable medical device. Using web-based questionnaires, the perception of pain (based on the pain self-efficacy questionnaire, visual analogue scale, pain catastrophizing scale, and brief pain inventory) and psychological variables (based on the hospital and anxiety depression scale and 12-item short form survey) will be assessed at the beginning of treatment, 1 week after the start of treatment, at the end of treatment, 1 month after the start of treatment, and 3 months after the start of treatment. The system's usability (based on the mobile app rating scale and system usability scale) and its involvement in the decision-making process (based on the 9-item shared decision-making questionnaire) will be also evaluated. Finally, at the end of the treatment, a digital focus group will be conducted with the 42 patients to explore their unexpressed needs and preferences concerning treatment.

RESULTS

The study project is scheduled to start in June 2023, and it is expected to be completed by August 2025.

CONCLUSIONS

We expect that the combination of tDCS and telemedicine programs will reduce pain perceived by patients with breast cancer and improve their mental well-being more effectively than single interventions. Furthermore, we assume that this home-based approach will also improve patients' participation in routine clinical care, reducing disparities in accessing health care processes. This integrated home care strategy could be useful for patients with breast cancer who cannot find relief from chronic pain with pharmacological treatments or for those who have limited access to care due to poor mobility or geographical barriers, thus increasing the patients' empowerment and reducing health care costs.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/49508.

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.

Rest-Activity Rhythm, Pain, and Motor Activity in Multiple Sclerosis

BACKGROUND

Although the relationships among physical disability, mood disorders, and pain are well described in multiple sclerosis (MS), little is known about whether those symptoms are associated with sleep disturbances.

METHODS

Forty-six patients with MS experiencing pain participated. Sleep was indirectly measured by assessing rest-activity rhythm via actigraphy: interdaily stability, intradaily variability, and relative amplitude. Pain was assessed using visual and verbal analog scales, mood by the Beck Depression Inventory and Symptom Checklist-90, and physical disability by the Expanded Disability Status Scale.

RESULTS

Incorporating mood, pain, and physical disability into 1 regression model resulted in a significant association with interdaily stability.

CONCLUSIONS

Compared with intradaily variability and relative amplitude, interdaily stability seems to be the most vulnerable actigraphy variable for mood disturbances, pain, and physical disabilities.

Transcranial Direct Current Stimulation in Nicotine Use: Nursing Implications for Patient Outcomes

ABSTRACT

Tobacco use is a leading cause of cancer, cardiovascular and respiratory disease, and preventable death in the United States. The brains of individuals with nicotine dependence are characterized by damaged mesolimbic pathways in the medial portion of the limbic and frontal lobes, creating positive reinforcing mechanisms. Transcranial direct current stimulation (tDCS) targets this neuroadaptation to improve smokers' nicotine-related outcomes, such as craving and smoking behavior, by depolarizing or hyperpolarizing the neurons of the brain. Recent literature reported promising outcomes in smokers after tDCS treatment interventions. tDCS has great potential for clinical nursing research for tobacco control given its multiple methodological advantages and few disadvantages. Nurse researchers can consider individualized and home-based tDCS interventions for community-based tobacco control research and may need to consider objective outcome measures (e.g., cotinine in urine) and addiction-related cognitive variables (e.g., self-regulation). Users of electronic nicotine delivery systems also need to be considered as participants in tDCS interventions. Additional considerations for nursing research are discussed.

Effects of repetitive twice-weekly transcranial direct current stimulations on fatigue and fatigability in people with multiple sclerosis

Fatigue is associated with a dramatically decreased quality of life in people with multiple sclerosis (pwMS). It refers to a constant subjective feeling of exhaustion and performance decline, known as fatigability. However, inconsistency and heterogeneity in defining and assessing fatigue have led to limited advances in understanding and treating MS-associated fatigue. Transcranial direct current stimulation (tDCS) has emerged as a promising, non-pharmaceutical treatment strategy for subjective fatigue. However, whether repetitive tDCS also have long-term effects on time-on-task performance has not yet been investigated. This pseudorandomized, single-blinded, and sham-controlled study investigated tDCS effects on behavioral and electrophysiological parameters. 18 pwMS received eight twice-weekly 30 min stimulations over the left dorsolateral prefrontal cortex. Fatigability was operationalized as time-on-task-related changes in reaction time variability and P300 amplitude. Additionally, subjective trait and state fatigue ratings were assessed. The results revealed an overall decrease in subjective trait fatigue ratings that lasted at least four weeks after the stimulations. However, the ratings declined after both anodal and sham tDCS. No effects were found on subjective state fatigue and objective fatigability parameters. Linear Mixed Models and Bayesian Regression models likewise favored the absence of a tDCS effect on fatigability parameters. The results confirm the complex relationship between MS-associated fatigue and fatigability. Reliable and clinically relevant parameters need to be established to extend the potential of tDCS for treating fatigability. Furthermore, our results indicate that consecutive stimulations rather than twice-weekly stimulations should be the preferred stimulation scheme in future studies.

Pain and cognitive performance in adults with multiple sclerosis: A systematic review

INTRODUCTION

Pain and cognitive dysfunction are separately known to be important manifestations of multiple sclerosis (MS). Although pain is a complex subjective phenomenon with affective and cognitive aspects, it is not known if people with MS reporting pain are at greater risk of reduced performance in objective tests of cognition. The presence or direction of any association remains to be clarified, as do the roles of confounders such as fatigue, medication and mood.

METHODS

We conducted a systematic review of studies examining the relationship between pain and objectively measured cognition in adults with confirmed MS, according to a pre-registered protocol (PROSPERO 42,020,171,469). We carried out searches in MEDLINE, Embase and PsychInfo. Studies of adults with any subtype of MS, with chronic pain and in which cognitive evaluation was conducted by validated instruments were included. We evaluated the role of potential confounders (medication, depression, anxiety, fatigue and sleep) and described findings by eight pre-specified cognitive domains. Risk of bias was assessed using the Newcastle-Ottawa Scale.

RESULTS

11 studies (n = 3714 participants, range 16 to 1890 per study) were included in the review. Four studies included longitudinal data. Nine studies identified a relationship between pain and objectively measured cognitive performance. In seven of these studies, higher pain scores were associated with poorer cognitive performance. However, no evidence was available for some cognitive domains. Heterogeneous study methodology precluded meta-analysis. Studies infrequently controlled for the specified confounders. Most studies were judged to be at risk of bias.

DISCUSSION

Several studies, but not all, identified a negative relationship between pain severity and objectively measured cognitive performance. Our ability to further characterise this relationship is limited by study design and lack of evidence in many cognitive domains. Future studies should better establish this relationship and delineate the neurological substrate underpinning it.

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 therapeutic potential of non-invasive brain stimulation for the treatment of Long-COVID-related cognitive fatigue

Following an acute COVID-19 infection, a large number of patients experience persisting symptoms for more than four weeks, a condition now classified as Long-COVID syndrome. Interestingly, the likelihood and severity of Long-COVID symptoms do not appear to be related to the severity of the acute COVID-19 infection. Fatigue is amongst the most common and debilitating symptoms of Long-COVID. Other symptomes include dyspnoea, chest pain, olfactory disturbances, and brain fog. Fatigue is also frequently reported in many other neurological diseases, affecting a broad range of everyday activities. However, despite its clinical significance, limited progress has been made in understanding its causes and developing effective treatment options. Non-invasive brain stimulation (NIBS) methods offer the unique opportunity to modulate fatigue-related maladaptive neuronal activity. Recent data show promising results of NIBS applications over frontoparietal regions to reduce fatigue symptoms. In this current paper, we review recent data on Long-COVID and Long-COVID-related fatigue (LCOF), with a special focus on cognitive fatigue. We further present widely used NIBS methods, such as transcranial direct current stimulation, transcranial alternating current stimulation, and transcutaneous vagus nerve stimulation and propose their use as possible therapeutic strategies to alleviate individual pathomechanisms of LCOF. Since NIBS methods are safe and well-tolerated, they have the potential to enhance the quality of life in a broad group of patients.

Is transcranial direct current stimulation beneficial for treating pain, depression, and anxiety symptoms in patients with chronic pain? A systematic review and meta-analysis

BACKGROUND

Chronic pain is often accompanied by emotional dysfunction. Transcranial direct current stimulation (tDCS) has been used for reducing pain, depressive and anxiety symptoms in chronic pain patients, but its therapeutic effect remains unknown.

OBJECTIVES

To ascertain the treatment effect of tDCS on pain, depression, and anxiety symptoms of patients suffering from chronic pain, and potential factors that modulate the effectiveness of tDCS.

METHODS

Literature search was performed on PubMed, Embase, Web of Science, and Cochrane Library from inception to July 2022. Randomized controlled trials that reported the effects of tDCS on pain and depression and anxiety symptoms in patients with chronic pain were included.

RESULTS

Twenty-two studies were included in this review. Overall pooled results indicated that the use of tDCS can effectively alleviate short-term pain intensity [standard mean difference (SMD): -0.43, 95% confidence interval (CI): -0.75 to -0.12, P = 0.007] and depressive symptoms (SMD: -0.31, 95% CI, -0.47 to -0.14, P < 0.001), middle-term depressive symptoms (SMD: -0.35, 95% CI: -0.58 to -0.11, P = 0.004), long-term depressive symptoms (ES: -0.38, 95% CI: -0.64 to -0.13, P = 0.003) and anxiety symptoms (SMD: -0.26, 95% CI: -0.51 to -0.02, P = 0.03) compared with the control group.

CONCLUSION

tDCS may be an effective short-term treatment for the improvement of pain intensity and concomitant depression and anxiety symptoms in chronic pain patients. Stimulation site, stimulation frequency, and type of chronic pain were significant influence factors for the therapeutic effect of tDCS.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=297693, identifier: CRD42022297693.

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.

Single Session Anodal Transcranial Direct Current Stimulation on Different Cortical Areas

Abstract. Transcranial direct current stimulation (tDCS) studies in healthy volunteers have shown conflicting results in terms of modulation in pain thresholds. The aim of this study was to investigate how single session anodal tDCS and modulated tDCS (mtDCS) of distinct cortical areas affected pain and perception thresholds in healthy participants. Five different stimulation conditions were applied at different cortical sites to 20 healthy volunteers to investigate the effects of tDCS and mtDCS (20 Hz) on pain and perception thresholds. TDCS over the motor cortex (M1), mtDCS over the motor cortex, tDCS over the dorsolateral prefrontal cortex (DLPFC), mtDCS of the DLPFC, and mtDCS over the occipital cortex were the stimulation conditions. All of the stimulations were anodal. The stimulations were given in a randomized order at 20-minute intervals. For comparison, electrical pain and perception thresholds were obtained from the right middle finger before and during the tDCS. After each measurement, participants were asked to give a score to their pain. In repeated measures analysis of variance (RM-ANOVA) test, the Condition × Time interaction showed no significant influence on changes in pain, perception thresholds, and pain scores ( p = .48, p = .89, and p = .50, respectively). However, regardless of the condition types, there was a significant difference in pain and perceptual thresholds during tDCS ( p = .01, p = .025, respectively). Our findings did not support difference in pain and perception modulation by a single session anodal tDCS over M1 and DLPFC compared to the occipital cortex in healthy volunteers. The increase in all thresholds during tDCS, irrespective of conditions, and peripheral sensations, including an active control group, taken together, suggest a placebo effect of active tDCS. Future studies about pain and perception in healthy subjects should consider the level of experimental pain and a strong placebo effect.

Can noninvasive Brain Stimulation Improve Pain and Depressive Symptoms in Patients With Neuropathic Pain? A Systematic Review and Meta-Analysis

CONTEXT

Noninvasive brain stimulations (NIBS) have been increasingly applied to the patients with neuropathic pain (NP), while the effectiveness of NIBS in the management of NP is still conflicting.

OBJECTIVES

To examine the effectiveness of NIBS on pain and depression symptoms of patients with NP.

METHODS

A comprehensive literature retrieval was performed on MEDLINE, Embase, PsycINFO, PEDro, and CENTRAL from the establishment of the databases to June 2021. Randomized controlled trials comparing NIBS with sham stimulation were included.

RESULTS

A total of thirteen trials comprising 498 participants met the inclusion criteria. The pooled analysis found a significant effect on the improvement of pain scores at post-treatment, favoring NIBS over sham stimulation (SMD = -0.60; 95% CI: -1.00 to -0.20; P = 0.004). Subgroup analysis showed that only transcranial direct current stimulation (tDCS) (SMD = -0.38; 95% CI: -0.71 to -0.04; P = 0.030) and high-frequency repetitive transcranial magnetic stimulation (H-rTMS) (SMD = -0.95; 95% CI: -1.85 to -0.04; P = 0.040) had positive effects on pain reduction among all types of NIBS. The favorable effects of NIBS remained significant at follow-up visit (SMD = -0.51; 95% CI: -0.79 to -0.23; P = 0.000), while only H-rTMS was found in subgroup analyses to significantly improve pain scales of the patients (SMD = -0.54; 95% CI: -0.85 to -0.24; P = 0.000). Additionally, overall NIBS showed no beneficial effect over sham stimulation in reducing depression symptoms of NP patients either at post-treatment (SMD = -0.19; 95% CI: -0.39 to 0.01; P = 0.061) or at follow-up visit (SMD = -0.18; 95% CI: -0.45 to 0.10; P = 0.202).

CONCLUSION

This meta-analysis revealed the analgesic effect of NIBS on patients with NP, while no beneficial effect was observed on reducing concomitant depression symptoms. The findings recommended the clinical application of NIBS in patients with NP.

Transcranial direct current stimulation in the management of phantom limb pain: a systematic review of randomized controlled trials

INTRODUCTION

Phantom limb pain (PLP) after amputation is a frequent entity that conditions the life of those who suffer it. Current treatment methods are not sufficiently effective for PLP management. We aim to analyze the clinical application of transcranial direct current (tDCS) in people with amputation suffering from PLP.

EVIDENCE ACQUISITION

The following databases were consulted in September 2021: MEDLINE, EMBASE, The Web of Science, PEDro, SCOPUS and SciELO. Randomized controlled trials investigating the use of tDCS in people with amputation undergoing PLP were selected. Demographic data, type and cause of amputation, time since amputation, stimulation parameters, and outcomes were extracted.

EVIDENCE SYNTHESIS

Six articles were included in this review (seven studies were considered because one study performed two individual protocols). All included studies evaluated PLP; six evaluated the phantom limb sensations (PLS) and two evaluated the psychiatric disorders. In all included studies the intensity and frequency of PLP was reduced, in three PLS were reduced, and in none study psychiatric symptoms were modified.

CONCLUSIONS

Anodic tDCS over the contralateral M1 to the affected limb, with an intensity of 1-2 mA, for 15-20 minutes seems to significantly reduce PLP in people with amputation. Single-session treatment could modify PLP intensity for hours, and multi-session treatment could modify PLP for months. Limited evidence suggests that PLS and psychiatric disorders should be treated with different PLP electrode placements. Further studies with larger sample size and longer follow-up times are needed to establish the priority of tDCS application in the PLP management.

Brain augmentation and neuroscience technologies: current applications, challenges, ethics and future prospects

Ever since the dawn of antiquity, people have strived to improve their cognitive abilities. From the advent of the wheel to the development of artificial intelligence, technology has had a profound leverage on civilization. Cognitive enhancement or augmentation of brain functions has become a trending topic both in academic and public debates in improving physical and mental abilities. The last years have seen a plethora of suggestions for boosting cognitive functions and biochemical, physical, and behavioral strategies are being explored in the field of cognitive enhancement. Despite expansion of behavioral and biochemical approaches, various physical strategies are known to boost mental abilities in diseased and healthy individuals. Clinical applications of neuroscience technologies offer alternatives to pharmaceutical approaches and devices for diseases that have been fatal, so far. Importantly, the distinctive aspect of these technologies, which shapes their existing and anticipated participation in brain augmentations, is used to compare and contrast them. As a preview of the next two decades of progress in brain augmentation, this article presents a plausible estimation of the many neuroscience technologies, their virtues, demerits, and applications. The review also focuses on the ethical implications and challenges linked to modern neuroscientific technology. There are times when it looks as if ethics discussions are more concerned with the hypothetical than with the factual. We conclude by providing recommendations for potential future studies and development areas, taking into account future advancements in neuroscience innovation for brain enhancement, analyzing historical patterns, considering neuroethics and looking at other related forecasts.

Effectiveness of non-pharmacological rehabilitation interventions in pain management in patients with multiple sclerosis: Systematic review and meta-analysis

BACKGROUND

Multiple sclerosis (MS) is a progressive inflammatory and autoimmune neurological disease caused by inflammation and demyelination of the central nervous system. Pain is a typical symptom of central nervous system demyelination, affecting 63% of adults with MS. Recently, the role of non-pharmacological pain management in patients is growing because the non-pharmacological interventions are considered safe, affordable, easy, and accessible. However, to date, no systematic reviews or meta-analyses have comprehensively examined the therapeutic effects of the variety of non-pharmacological therapeutic interventions in the management of pain in patients with MS.

OBJECTIVE

The study aimed to conduct a systematic review with meta-analysis to assess the effectiveness of the non-pharmacological rehabilitation interventions in pain management in patients with MS.

METHODS

A comprehensive search using PubMed, Cochrane, and Science Direct databases was performed and included all randomized controlled trials, randomized cross-over trials, and quasi-experimental trials assessing the effect of non-pharmacological interventions for managing pain in patients with MS. This study was conducted according to PRISMA guidelines of a systematic review and pair-wise meta-analysis. Meta-analyses were performed by calculating the standardized mean difference at a 95% confidence interval using Review Manager software.

RESULTS

Twenty-nine papers were included in the systematic review, and only 22 of them were included in the meta-analysis. The pooled analysis showed a significant effect of neuromodulation and transcranial direct current stimulation on pain intensity reduction in patients with MS (SMD -0.51, 95% CI -0.51 to -0.09, P = 0.02), (SMD -0.67, 95% CI -1.18 to -0.16 P = 0.01), respectively. The analysis showed significant improvement in pain intensity in patient with MS after mind-body therapies (SMD -0.45, 95% CI -0.82 to -0.7, P = 0.02), mindfulness (SMD -0.55, 95% CI -0.96 to -0.14, P = 0.009), hypnosis (SMD -0.88, 95% CI -1.30 to -0.46, P = 0.0001), trigger point therapies (SMD -0.83, 95% CI -1.65 to -0.01, P = 0.05) and cognitive behavioral therapy (SMD -0.64, 95% CI -1.18 to -0.11, P = 0.02). However, there is no significant effect of relaxation therapy on pain reduction in patients with MS (SMD -0.82, 95% CI -1.94 to 0.31, P = 0.15).

CONCLUSIONS

The results indicated that the majority of the non-pharmacological rehabilitation interventions showed potential therapeutic effects in reducing pain intensity in patients with MS.

Transcranial Direct Current Stimulation of the Dorsolateral Prefrontal Cortex for Treatment of Neuropsychiatric Disorders

Background

The dorsolateral prefrontal cortex (DLPFC) is a key node of the frontal cognitive circuit. It is involved in executive control and many cognitive processes. Abnormal activities of DLPFC are likely associated with many psychiatric diseases. Modulation of DLPFC may have potential beneficial effects in many neural and psychiatric diseases. One of the widely used non-invasive neuromodulation technique is called transcranial direct current stimulation (or tDCS), which is a portable and affordable brain stimulation approach that uses direct electrical currents to modulate brain functions.

Objective

This review aims to discuss the results from the past two decades which have shown that tDCS can relieve clinical symptoms in various neurological and psychiatric diseases.

Methods

Here, we performed searches on PubMed to collect clinical and preclinical studies that using tDCS as neuromodulation technique, DLPFC as the stimulation target in treating neuropsychiatric disorders. We summarized the stimulation sites, stimulation parameters, and the overall effects in these studies.

Results

Overall, tDCS stimulation of DLPFC could alleviate the clinical symptoms of schizophrenia, depression, drug addiction, attention deficit hyperactivity disorder and other mental disorders.

Conclusion

The stimulation parameters used in these studies were different from each other. The lasting effect of stimulation was also not consistent. Nevertheless, DLPFC is a promising target for non-invasive stimulation in many psychiatric disorders. TDCS is a safe and affordable neuromodulation approach that has potential clinical uses. Larger clinical studies will be needed to determine the optimal stimulation parameters in each condition.

Non-invasive Brain Stimulation for Central Neuropathic Pain

The research and clinical application of the noninvasive brain stimulation (NIBS) technique in the treatment of neuropathic pain (NP) are increasing. In this review article, we outline the effectiveness and limitations of the NIBS approach in treating common central neuropathic pain (CNP). This article summarizes the research progress of NIBS in the treatment of different CNPs and describes the effects and mechanisms of these methods on different CNPs. Repetitive transcranial magnetic stimulation (rTMS) analgesic research has been relatively mature and applied to a variety of CNP treatments. But the optimal stimulation targets, stimulation intensity, and stimulation time of transcranial direct current stimulation (tDCS) for each type of CNP are still difficult to identify. The analgesic mechanism of rTMS is similar to that of tDCS, both of which change cortical excitability and synaptic plasticity, regulate the release of related neurotransmitters and affect the structural and functional connections of brain regions associated with pain processing and regulation. Some deficiencies are found in current NIBS relevant studies, such as small sample size, difficulty to avoid placebo effect, and insufficient research on analgesia mechanism. Future research should gradually carry out large-scale, multicenter studies to test the stability and reliability of the analgesic effects of NIBS.

Causal evidence of the roles of the prefrontal and occipital cortices in modulating the impact of color on moral judgement

Moral judgment is known to be affected by factors such as color. Previous research has shown that the colors black and white are particularly important, however, the neural mechanisms underlying this effect remain unclear. This study aimed to investigate the causal relationship between specific brain regions (left dorsolateral prefrontal cortex, left DLPFC and occipital cortex, OC) and their impact of black and white moral judgement by using transcranial direct current stimulation (tDCS). The results of Experiment 1 (N = 54) and Experiment 2 (N = 66) showed that anodal tDCS over the left DLPFC inhibited the impact of black and white on moral judgment while cathodal tDCS over the left DLPFC enhanced the effect. Conversely, anodal tDCS over the OC enhanced the impact of white on moral judgment, while cathodal tDCS over the OC inhibited it. Together these results suggest that moral judgment relies not only on the cognitive control network, but also brain regions important for sensory perception. The current findings provide enhanced insight into how colors can impact moral judgments.

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.

Attentional networks in neurodegenerative diseases: anatomical and functional evidence from the Attention Network Test

INTRODUCTION

Understanding alterations to brain anatomy and cognitive function associated with neurodegenerative diseases remains a challenge for neuroscience today. In experimental neuroscience, several computerised tests have been developed to contribute to our understanding of neural networks involved in cognition. The Attention Network Test (ANT) enables us to measure the activity of 3 attentional networks (alertness, orienting, and executive function).

OBJECTIVES

The main aim of this review is to describe all the anatomical and functional alterations found in diverse neurological diseases using the ANT.

MATERIAL AND METHODS

We collected studies published since 2010 in the PubMed database that employed the ANT in different neurological diseases. Thirty-two articles were obtained, addressing multiple sclerosis, epilepsy, and Parkinson's disease, among other disorders.

CONCLUSIONS

Some of the anatomical structures proposed in the 3 attentional networks model were confirmed. The most relevant structures in the alertness network are the prefrontal cortex, parietal region, thalamus, and cerebellum. The thalamus is also relevant in the orienting network, together with posterior parietal regions. The executive network does not depend exclusively on the prefrontal cortex and anterior cingulate cortex, but also involves such subcortical structures as the basal ganglia and cerebellum and their projections towards the entire cortex.

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.

Multiple sclerosis: Inflammation, autoimmunity and plasticity

In recent years, experimental studies have clarified that immune system influences the functioning of the central nervous system (CNS) in both physiologic and pathologic conditions. The neuro-immune crosstalk plays a crucial role in neuronal development and may be critically involved in mediating CNS response to neuronal damage. Multiple sclerosis (MS) represents a good model to investigate how the immune system regulates neuronal activity. Accordingly, a growing body of evidence has demonstrated that increased levels of pro-inflammatory mediators may significantly impact synaptic mechanisms, influencing overall neuronal excitability and synaptic plasticity expression. In this chapter, we provide an overview of preclinical data and clinical studies exploring synaptic functioning noninvasively with transcranial magnetic stimulation (TMS) in patients with MS. Moreover, we examine how inflammation-driven synaptic dysfunction could affect synaptic plasticity expression, negatively influencing the MS course. Contrasting CSF inflammation together with pharmacologic enhancement of synaptic plasticity and application of noninvasive brain stimulation, alone or in combination with rehabilitative treatments, could improve the clinical compensation and prevent the accumulating deterioration in MS.

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.

A randomized controlled trial to explore the efficacy and safety of transcranial direct current stimulation on patients with post-stroke fatigue

BACKGROUND

Post-stroke fatigue seriously affects the quality of life for stroke patients. There is no effective treatment at present. transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation which may have therapeutic effect on post-stroke fatigue. This study will explore about this.

METHOD

A total of 60 patients with post-stroke fatigue were randomly divided into the control group and the treatment group with 30 patients each by minimization randomization. Both groups received basic treatment and conventional rehabilitation. In the treatment group, patients were treated with active tDCS, while in the control group, sham tDCS. Both active and sham tDCS were administered 6 times a week for 4 weeks. Before and after the trial, the Fatigue Severity Scale (FSS), Fugl-Meyer Assessment (FMA) and Modified Barthel Index (MBI) were evaluated and analyzed. And comparisons were made among groups. And there were an 8-week follow-up after the intervention.

RESULT

Before the intervention, there were no significant differences in baseline data and assessment scores between the groups (P > 0.05). After 4 weeks of intervention, FSS scores in the treatment group were significantly lower than those in the control group (P = 0.012), and FMA and BMI scores were significantly higher than those in the control group (P < 0.05). There was no significant change in FSS scores after 8 months of follow-up (P > 0.05).

DISCUSSION

TDCS is a safe treatment that can effectively reduce the degree of fatigue after stroke, improve the motor function and daily activity ability of patients after stroke, and the efficacy is better than only routine rehabilitation training.

TRIAL REGISTRATION NUMBER

Chinese Clinical Trial Registry, ChiCTR2000031120. Registered on March 22, 2020.

Effects of transcranial direct current stimulation on cognitive dysfunction in multiple sclerosis

BACKGROUND

Around 40%-70% of patients with multiple sclerosis (MS) may experience cognitive impairments during the course of their disease with detrimental effects on social and occupational activities. Transcranial direct current stimulation (tDCS has been investigated in pain, fatigue, and mood disorders related to MS, but to date, few studies have examined effects of tDCS on cognitive performance in MS.

OBJECTIVE

The current study aimed to investigate the effects of a multi-session tDCS protocol on cognitive performance and resting-state brain electrical activities in patients with MS.

METHODS

Twenty-four eligible MS patients were randomly assigned to real (anodal) or sham tDCS groups. Before and after 8 consecutive daily tDCS sessions over the left dorsolateral prefrontal cortex (DLPFC), patients' cognitive performance was assessed using the Cambridge Brain Sciences-Cognitive Platform (CBS-CP). Cortical electrical activity was also evaluated using quantitative electroencephalography (QEEG) analysis at baseline and after the intervention.

RESULTS

Compared to the sham condition, significant improvement in reasoning and executive functions of the patients in the real tDCS group was observed. Attention was also improved considerably but not statistically significantly following real tDCS. However, no significant changes in resting-state brain activities were observed after stimulation in either group.

CONCLUSION

Anodal tDCS over the left DLPFC appears to be a promising therapeutic option for cognitive dysfunction in patients with MS. Larger studies are required to confirm these findings and to investigate underlying neuronal mechanisms.

Is Allodynia a Determinant Factor in the Effectiveness of Transcranial Direct Current Stimulation in the Prophylaxis of Migraine?

OBJECTIVES

Allodynia, the clinical marker of central sensitization, affects even simple daily living activities and increases the tendency for migraine to be more resistant to treatment and have a chronic course. Migraine that impairs quality of life can often be treated with variable pharmaceutical agents, but with various side effects. Transcranial direct current stimulation (tDCS) is a potential alternative treatment for migraine prophylaxis.

MATERIALS AND METHODS

Seventy-seven patients diagnosed with migraine (48 with allodynia and 29 without allodynia) were included in the study. Randomly, 41 of the 77 patients received sham stimulation and 36 patients underwent three sessions of anodal left primary motor cortex stimulation for 2 mA, 20 min. Migraine attack characteristics (frequency, severity, and duration) and analgesic drug use were followed with headache diaries for one month after the stimulation.

RESULTS

After tDCS, migraine attack frequency (p = 0.021), the number of headache days (p = 0.005), duration of attacks (p = 0.008), and symptomatic analgesic drug use (p = 0.007) decreased in patients receiving active tDCS, compared to the sham group. The therapeutic gain of tDCS was calculated as 44% (95% confidence interval [CI]: 22-60%) for headache days and 76% (95% CI: 55-86) for headache duration. Response to tDCS treatment was higher in patients without allodynia (60% vs. 24%; p = 0.028) and allodynia came out as an independent predictor of response to tDCS with logistic regression analysis. Side effects were rare and similar to the sham group.

CONCLUSIONS

tDCS is a safe, efficacious, and fast method for migraine prophylaxis. However, the administration of tDCS before allodynia occurs, that is, before central sensitization develops, will provide increased responsiveness to the treatment.

SIGNIFICANCE

tDCS is more effective before the development of allodynia, but it also improves the quality of life even after the development of allodynia.

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.

Effects of Transcranial Direct Current Stimulation on Cognition, Mood, Pain, and Fatigue in Multiple Sclerosis: A Systematic Review and Meta-Analysis

Background: The study aimed to evaluate the effects of transcranial direct current stimulation (tDCS) on cognition, mood disturbance, pain, and fatigue in people with multiple sclerosis (PwMS).

Methods: A literature search was performed on articles published between January 1990 and May 2020 in Pubmed, Medline, and Web of Science using the following keywords and their abbreviation in combinations: multiple sclerosis and transcranial direct current stimulation. Mean effect size (ES) and 95% confidence interval were calculated for each domain of interest.

Results: Seventeen articles with a total of 383 PwMS were included in this analysis. For cognition, a strong effect size was found for the trial administering the Symbol Digit Modalities Test (ES: 1.15), whereas trials applying the Attention Network Test showed a negative effect size of −0.49. Moderate to strong effect sizes were observed for mood disturbance (mean ES: 0.92), pain (mean ES: 0.59), and fatigue (mean ES: 0.60). Further subgroup analyses for MS-related fatigue showed that both high and low intensities of stimulation lead to nearly the same degree of favorable effects. More pronounced effects were observed in studies administering the Fatigue Severity Scale compared with studies using other fatigue measures such as the Modified Fatigue Impact Scale.

Conclusion: These results provide preliminary evidence that tDCS has a favorable effect on cognitive processing speed, mood disturbance, pain, and fatigue in MS. However, the effects on cognition and fatigue vary based on the specific assessment used.

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”.

dmPFC-vlPAG projection neurons contribute to pain threshold maintenance and antianxiety behaviors

The dorsal medial prefrontal cortex (dmPFC) has been recognized as a key cortical area for nociceptive modulation. However, the underlying neural pathway and the function of specific cell types remain largely unclear. Here, we show that lesions in the dmPFC induced an algesic and anxious state. Using multiple tracing methods including a rabies-based transsynaptic tracing method, we outlined an excitatory descending neural pathway from the dmPFC to the ventrolateral periaqueductal gray (vlPAG). Specific activation of the dmPFC/vlPAG neural pathway by optogenetic manipulation produced analgesic and antianxiety effects in a mouse model of chronic pain. Inhibitory neurons in the dmPFC were specifically activated using a chemogenetic approach, which logically produced an algesic and anxious state under both normal and chronic pain conditions. Antagonists of the GABAA receptor (GABAAR) or mGluR1 were applied to the dmPFC, which produced analgesic and antianxiety effects. In summary, the results of our study suggest that the dmPFC/vlPAG neural pathway might participate in the maintenance of pain thresholds and antianxiety behaviors under normal conditions, while silencing or suppressing the dmPFC/vlPAG pathway might be involved in the initial stages and maintenance of chronic pain and the emergence of anxiety-like behaviors.

The emotional disorders associated with multiple sclerosis

Multiple sclerosis (MS) is associated with a high prevalence of emotional and mood disorders. Emotional disorders may worsen during illness progression and affect the quality of life of patients and their families. MS is often associated with depression, with an increased risk of suicide, poor adherence to treatment, decreased functional status, and quality of life. The diagnosis and treatment of emotional and mood disorders in these patients is often challenging since several symptoms of these disorders overlap with those of MS. Other prevalent emotional disorders in MS include bipolar disorder, anxiety disorders, emotional blunting (apathy), and pseudobulbar affect. Early recognition and treatment of these comorbidities could contribute to the reduction of disability and even to decreased mortality. The aim of this chapter is to provide an up-to-date review of mood and emotional disorders that are often associated with MS, focusing on their epidemiology, clinical features, pathogenesis, assessment, and treatment. The interplay between the psychosocial impact of the chronic disability and the demyelinating structural lesions of the brain in precipitating emotional and mood disorders is discussed, as well as its implications for diagnosis and treatment.

Non-invasive Brain and Spinal Stimulation for Pain and Related Symptoms in Multiple Sclerosis: A Systematic Review

Background: Neuropathic and nociceptive pain frequently affect patients with multiple sclerosis (MS), with a prevalence close to 90% and significant impact on general health and quality of life. Pharmacological strategies are widely used to treat pain in MS, but their effectiveness and side-effects are controversial. Among non-pharmacological treatments for pain, non-invasive brain and spinal stimulation (NIBSS) has shown promising preliminary results in MS.

Objective: Systematic review to investigate the effect of NIBSS for the management of pain in MS.

Methods: A literature search using Pubmed, Science Direct and Web of Science was conducted from databases inception to February 21, 2020 for studies assessing the analgesic effect of NIBSS on pain in MS.

Results: A total of 279 records were title- and abstract-screened, nine were assessed for full text and included. The NIBSS techniques explored were transcranial direct current stimulation (N = 5), transcranial magnetic stimulation (N = 2), transcranial random noise stimulation (N =1), transcutaneous spinal direct current stimulation (N = 1). The targets were the primary motor cortex (M1; N = 4), the left dorsolateral pre-frontal cortex (DLPFC; N = 3), the spinal cord (N = 1), unspecified brain target (N = 1). The study designs were randomized (N = 7), open label (N = 1), single case report (N = 1). Despite the differences in study design, target and NIBSS technique that impeded a meta-analysis, all the studies converge in showing a significant improvement of pain after active NIBSS with less consistent effects on other symptoms of the pain-related cluster (depression, fatigue, cognition) and quality of life.

Conclusions: Excitatory NIBSS over M1, left DLPFC and spinal cord appear to be the most effective protocols for pain in MS. Open questions include the use of neurophysiological or neuroimaging surrogate outcome measures, the stratification of patients according to the clinical profiles and underlying pathogenetic mechanisms and the combination of NIBSS to pharmacological treatment, neurorehabilitation, or psychotherapy to improve the clinical effect. The duration of the effect to NIBSS and the feasibility and efficacy of telemedicine NIBSS protocols are other open key questions.

Effects of Transcranial Direct Current Stimulation on Information Processing Speed, Working Memory, Attention, and Social Cognition in Multiple Sclerosis

Multiple Sclerosis (MS) is a chronic inflammatory disease of the central nervous system. Cognitive impairment occurs in 40-65% of patients and could drastically affect their quality of life. Deficits could involve general cognition (e.g., attention and working memory) as well as social cognition. Transcranial direct current stimulation (tDCS), is a novel brain stimulation technique that has been assessed in the context of several neuropsychiatric symptoms, including those described in the context of MS. However, very rare trials have assessed tDCS effects on general cognition in MS, and none has tackled social cognition. The aim of this work was to assess tDCS effects on general and social cognition in MS. Eleven right-handed patients with MS received two blocks (bifrontal tDCS and sham, 2 mA, 20 min, anode/cathode over left/right prefrontal cortex) of 5 daily stimulations separated by a 3-week washout interval. Working memory and attention were, respectively, measured using N-Back Test (0-Back, 1-Back, and 2-Back) and Symbol Digit Modalities Test (SDMT) at the first and fifth day of each block and 1 week later. Social cognition was evaluated using Faux Pas Test and Eyes Test at baseline and 1 week after each block. Interestingly, accuracy of 1-Back test improved following sham but not active bifrontal tDCS. Therefore, active bifrontal tDCS could have impaired working memory via cathodal stimulation of the right prefrontal cortex. No significant tDCS effects were observed on social cognitive measures and SDMT. Admitting the small sample size and the learning (practice) effect that might arise from the repetitive administration of each task, the current results should be considered as preliminary and further investigations in larger patient samples are needed to gain a closer understanding of tDCS effects on cognition in MS.

Attentional networks in neurodegenerative diseases: anatomical and functional evidence from the Attention Network Test

INTRODUCTION

Understanding alterations to brain anatomy and cognitive function associated with neurodegenerative diseases remains a challenge for neuroscience today. In experimental neuroscience, several computerised tests have been developed to contribute to our understanding of neural networks involved in cognition. The Attention Network Test (ANT) enables us to measure the activity of 3 attentional networks (alertness, orienting, and executive function).

OBJECTIVES

The main aim of this review is to describe all the anatomical and functional alterations found in diverse neurological diseases using the ANT.

MATERIAL AND METHODS

We collected studies published since 2010 in the PubMed database that employed the ANT in different neurological diseases. Thirty-two articles were obtained, addressing multiple sclerosis, epilepsy, and Parkinson's disease, among other disorders.

CONCLUSIONS

Some of the anatomical structures proposed in the 3 attentional networks model were confirmed. The most relevant structures in the alertness network are the prefrontal cortex, parietal region, thalamus, and cerebellum. The thalamus is also relevant in the orienting network, together with posterior parietal regions. The executive network does not depend exclusively on the prefrontal cortex and anterior cingulate cortex, but also involves such subcortical structures as the basal ganglia and cerebellum and their projections towards the entire cortex.

Clinical perspective on pain in multiple sclerosis

Pain is an important and frequent symptom in multiple sclerosis (MS), which leads to a low quality of life, increased disability level, and lack of employment and mental health. Recently, studies have shown increased interest in pain in MS and there is a growing evidence of its prevalence. However, the literature suffers from lack of experimental studies focusing on pain reduction. This topical review summarizes the current knowledge about pain in MS with its definitions, assessments, treatments and rehabilitation within a holistic perspective.

The Impact of Anodal tDCS on the Attentional Networks as a Function of Trait Anxiety and Depressive Symptoms: A Preregistered Double-Blind Sham-Controlled Experiment

OBJECTIVE

Attention is a multifaceted construct, including three distinct attentional networks: the alerting, orienting, and executive conflict networks. Recently, researchers have started to envision strategies to enhance the attentional networks, and transcranial Direct Current Stimulation (tDCS) has emerged as a promising tool to do so, especially regarding the executive conflict network. On the other hand, other research lines have suggested that anodal tDCS might yield more substantial impacts among depressive and anxious participants.

METHOD

In this preregistered study, we thus examined two questions. First, we wanted to replicate previous observations and tested whether anodal tDCS does improve the executive conflict network's efficiency. Second, we set out to clarify the impact of anxiety and depressive symptoms on this effect. To do so, we adopted a double-blind within-subject protocol in an unselected sample (n = 50) and delivered a single session of anodal- applied over the dorsolateral part of the left prefrontal cortex-versus sham tDCS during the completion of a task assessing the attentional networks. We assessed anxiety and depressive symptoms at baseline.

RESULTS AND CONCLUSIONS

Although there were no significant direct effects of tDCS on the attentional networks, we found that the higher the levels of depression and trait anxiety, the larger the executive conflict network's enhancement during tDCS. By highlighting the importance of trait anxiety and depression when considering the impact of tDCS on the attentional networks, this study fulfills a valuable niche in clinical neuroscience, wherein preclinical data provide critical clues for larger, more definitive future translational efforts.

Comparing the effects of multi-session anodal trans-cranial direct current stimulation of primary motor and dorsolateral prefrontal cortices on fatigue and quality of life in patients with multiple sclerosis: a double-blind, randomized, sham-controlled trial

OBJECTIVE

To compare the effects of anodal trans-cranial direct current stimulation (a-tDCS) over primary motor and dorsolateral prefrontal cortices on Fatigue Severity Scale and its lasting effect on fatigue reduction and improvement in quality of life in patients with multiple sclerosis.

DESIGN

A randomized, double-blinded, sham-controlled parallel clinical trial study.

SETTING

Neurological physiotherapy clinics.

SUBJECTS

Thirty-nine participants were randomly assigned to three groups: dorsolateral prefrontal cortex a-tDCS, primary motor a-tDCS (experimental groups) and sham a-tDCS. Finally, 36 participants completed the whole study (n = 12 in each group).

INTERVENTIONS

Participants in the experimental groups received six-session a-tDCS (1.5 mA, 20 minutes) during two weeks (three sessions per week). The sham group received six sessions of 20-minute sham stimulation.

MAIN MEASURES

The Fatigue Severity Scale and quality of life were assessed before, immediately and four weeks after the intervention.

RESULTS

Findings indicated a significant reduction in the Fatigue Severity Scale and a significant increase in the quality of life in both experimental groups, immediately after the intervention (P < 0.001), while Fatigue Severity Scale and quality of life changes were not significant in the sham a-tDCS group (P > 0.05). In addition, improvement of the variables remained four weeks after the intervention in dorsolateral prefrontal cortex a-tDCS (mean differences (95% confidence interval): 0.03 (-0.63 to 0.68) as compared to primary motor (-0.62 (-0.11 to -1.14) and sham a-tDCS groups (-0.47 (-1.37 to 0.43)).

CONCLUSION

Both primary motor and dorsolateral prefrontal cortex a-tDCS as compared to sham intervention can immediately improve fatigue and quality of life. However, the effects last up to four weeks only by the dorsolateral prefrontal cortex a-tDCS.