Self-administered transcranial direct current stimulation for pain in older adults with knee osteoarthritis: A randomized controlled study

Transcranial direct current stimulation alleviates the pain severity in people suffering from knee osteoarthritis: a systematic review and meta-analysis

Considerable research has shown the benefits of transcranial direct current stimulation (tDCS) for the alleviation of pain associated with knee osteoarthritis (KOA). Still, a large variance in study protocols and observations across publications exists. We here thus completed a systematic review and meta-analysis to comprehensively and quantitatively characterize the effects of tDCS on KOA-related pain. A search strategy based on the Population, Intervention, Comparison, Outcome, and Study design (PICOS) principle was used to obtain the publications in 7 databases. Studies exploring the effects of tDCS on KOA-related pain were screened, and eligible studies were included. Ten studies of 518 participants using Visual Analogue Scale or Numeric Rating Scale to assess pain were included in the systematic review, and 9 of them were included in meta-analysis. The quality of these studies was good. Compared to control, tDCS induced significant short-term improvements in KOA-related pain with medium heterogeneity (standardized mean difference [SMD] = -0.91, 95% confidence interval [-1.24, -0.58], P < 0.001, I2 = 61%). Subgroup analyses showed that both home-based (SMD = -1.32, 95% CI [-1.65, -0.99], P < 0.001, I 2 = 0%) and laboratory-based intervention (SMD = -0.66, 95% CI [-0.99, -0.33], P < 0.001, I 2 = 40%) with at least 5 sessions per week (SMD = -1.02, 95% CI [-1.41, -0.64], P < 0.001, I 2 = 65%) and/or with a total number of at least 10 sessions (SMD = -1.12, 95% CI [-1.51, -0.74], P < 0.001, I 2 = 59%) can induce maximum benefits for the alleviation of KOA-related pain. The results here showed that tDCS is of great promise to alleviate KOA-related pain. Still, future studies with more rigorous design are needed to confirm the observations from this work, which can ultimately help the determination of appropriate intervention protocol that can maximize such benefits.

Exploring whether home-based neuromodulation can boost the analgesic effects of exercise in people with knee osteoarthritis: protocol for a double-blinded, pilot randomised controlled trial

INTRODUCTION

Knee osteoarthritis (OA) represents a leading cause of disability globally. Exercise has been demonstrated to improve pain and function in people with knee OA. However, when in pain, commencement of exercise is difficult, and clinical effects with such interventions are often modest. Recently, transcranial direct current stimulation (tDCS), a form of non-invasive brain stimulation, has been shown to bolster the pain-relieving effect of exercise in experimental settings. While promising, the utility of employing this approach beyond the research environment is yet to be elucidated. Therefore, this pilot study aims to investigate the feasibility, safety, adherence, tolerability and preliminary efficacy of tDCS and exercise in home-based settings to improve pain and function in people with knee OA.

METHODS AND ANALYSIS

This protocol is for a pilot randomised, double-blinded, sham-controlled trial. 24 individuals with idiopathic knee OA will be randomised to receive either active tDCS+exercise (Intervention) or sham tDCS+exercise (Control) at home. Participants will receive 20 min of tDCS 5 days per week for the first 2 weeks of this 8-week trial. Participants in both groups will complete a lower limb strengthening programme 3 days per week for the entire 8 weeks. Outcome measures of feasibility (acceptability, satisfaction, retention), safety, adherence and tolerability will be assessed throughout the trial period, with clinical outcomes of pain and function assessed before and following the intervention. Feasibility, safety, adherence and tolerability outcomes will be explored descriptively using frequencies and percentages. To examine preliminary efficacy, within-group and between-group changes in pain and functional measures will be analysed.

ETHICS AND DISSEMINATION

This protocol obtained ethical approval from the Queensland University of Technology Human Research Ethics Committee (HREA 2024-8302-20200). All participants will provide written informed consent. The findings of the study will be disseminated via journal publications and international conference proceedings.

TRIAL REGISTRATION NUMBER

ACTRN12624000397516p.

Effects of transcranial direct current stimulation on pain and physical function in patients with knee osteoarthritis: a systematic review and meta-analysis

BACKGROUND

Keen Osteoarthritis (KOA) is a common chronic disabling disease characterized by joint pain and dysfunction, which seriously affects patients' quality of life. Recent studies have shown that transcranial direct current stimulation (tDCS) was a promising treatment for KOA.

PURPOSE

Investigate the effects of tDCS on pain and physical function in patients with KOA.

METHODS

Randomized controlled trials related to tDCS and KOA were systematically searched in the PubMed, Embase, Medline, Cochrane Library, CINHL, and Web of Science databases from inception to July 23, 2024. The pain intensity was evaluated using the visual analog scale or the numeric rating scale, and the pain sensitivity was assessed using conditioned pain modulation, pressure pain threshold, heat pain threshold, or heat pain tolerance. The physical function outcome was evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index or the Knee injury and Osteoarthritis Outcome Score. Statistical analysis was performed using Review Manager 5.4.

RESULTS

Seven studies with a total of 503 participants were included. Compared to sham tDCS, tDCS was effective in reducing the short-term pain intensity (SMD: -0.58; 95% CI: -1.02, -0.14; p = 0.01) and pain sensitivity (SMD: -0.43; 95% CI: -0.70, -0.16; p = 0.002) but failed to significantly improve the long-term pain intensity (SMD: -0.26; 95% CI: -0.59, 0.08; p = 0.13) in KOA patients. In addition, tDCS did not significantly improve the short-term (SMD: -0.13; 95% CI: -0.35, 0.08; p = 0.22) and long-term (SMD: 0.02; 95% CI: -0.22, 0.25; p = 0.90) physical function in patients with KOA.

CONCLUSIONS

The tDCS can reduce short-term pain intensity and sensitivity but fails to significantly relieve long-term pain intensity and improve the physical function in patients with KOA. Thus, tDCS may be a potential therapeutic tool to reduce short-term pain intensity and pain sensitivity in patients with KOA.

Comparison of responders and nonresponders with knee osteoarthritis after transcranial direct current stimulation

AIM

The study compared responders and nonresponders to transcranial direct current stimulation (tDCS) regarding clinical pain outcomes in knee osteoarthritis (OA) patients.

PATIENTS AND METHODS/MATERIALS

Sixty participants received home-based active tDCS, and clinical pain outcomes were compared between responders and nonresponders.

RESULTS

Latent class growth analyses classified 41 participants as responders and 19 as nonresponders. Responders showed significantly greater decreases in pain intensity from baseline to post intervention than nonresponders (p < .001). Participants with higher BMI (p = .02) and weight (p = .005) were more likely to respond, while no significant sociodemographic differences were found.

CONCLUSIONS

Identifying characteristics of nonresponsive tDCS subgroups can tailor treatments for each group.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov identifier is NCT04016272.

The effects of combined transcranial direct Current stimulation with physiotherapy for physical function in subjects with knee osteoarthritis: a systematic review and meta-analysis

BACKGROUND

Transcranial Direct Current Stimulation (tDCS) emerges as a promising therapeutic intervention for knee osteoarthritis (KOA), yet its impact on physical function remains insufficiently explored.

OBJECTIVES

To evaluate the relative effects of tDCS for physical function in patients with KOA.

METHODS

Pubmed, Web of Science, Scopus and Cochrane Database were explored as of August 2023 to identify studies to be included in the current systematic review and metaanalysis. Randomized controlled trials in patients with KOA comparing tDCS with placebo were included. The outcomes defined were measures of physical function (questionnaires, gait, or physical performance). The Risk of Bias tool was used to assess bias in the randomized controlled trials, whereas the PEDro scale was applied for methodological quality, and the certainty of evidence for each outcome was assessed through GRADE. Results for each outcome were synthesized using meta-analysis (random-effects model, I2-test for heterogeneity) and a subgroup analysis was performed to improve the sensitivity of the results and to explore potential moderating factors of the effect sizes.

RESULTS

Ten studies with good to excellent quality were included, analyzing a total of 628 participants. Regarding physical function, tDCS showed a favorable effect (ES: -0.58; 95%CI -0.82, -0.33; I2: 52.1%) with a low risk of bias and low to moderate certainty of evidence. The concurrent application of physiotherapy interventions and tDCS improved the effects on pain and function. Applying physiotherapy interventions, as well as adding peripheral currents, increased the effect sizes (ES: -0.95, k = 3, p = .018; ES: -0.95, k = 4 p = .001, respectively). The pattern of application of the tDCS, either daily or in alternate days, did not moderate the effect size (p = .619). Meta-regression revealed that the number of tDCS sessions did not moderate the effect size either (p = .242).

CONCLUSION

The tDCS might be a promising therapeutic approach to enhance physical function in subjects affected with KOA. However, further systematic reviews with meta-analyses should be performed with standardized and proven-efficacy physiotherapy programs, as well as with long-term results, to ascertain whether the improvement may be sustained over time. This study provides valuable insights into optimizing tDCS interventions for enhanced outcomes in the management of KOA.Protocol available via PROSPERO [CRD42023440676].

The Efficacy of the Addition of tDCS and TENS to an Education and Exercise Program in Subjects with Knee Osteoarthritis: A Randomized Controlled Trial

Knee osteoarthritis (KOA) has a significant impact on patients' quality of life. This study aimed to assess the effectiveness of integrating transcranial direct current stimulation (tDCS) and transcutaneous electrical nerve stimulation (TENS) into an education and exercise program with the aim of decreasing pain and improving physical function in KOA. A randomized controlled trial with 65 KOA patients was conducted. The subjects were assigned to one of the following three groups: education and active exercise plus (1) double active tDCS and TENS, (2) active tDCS and sham TENS, and (3) double sham tDCS and TENS. Sessions were conducted over a 20 min period, whilst data on pain, chronic pain clinical variables, and physical function were collected. Although all groups showed improvement in pain-related symptoms in the short and medium term, the addition of tDCS and/or TENS did not significantly enhance the benefits of the exercise and education program. These findings suggest that an education and active exercise program in the treatment of KOA has a positive effect on pain, with or without the addition of tDCS and/or TENS.

Targeting Prefrontal Cortex Dysfunction in Pain

The prefrontal cortex (PFC) has justifiably become a significant focus of chronic pain research. Collectively, decades of rodent and human research have provided strong rationale for studying the dysfunction of the PFC as a contributing factor in the development and persistence of chronic pain and as a key supraspinal mechanism for pain-induced comorbidities such as anxiety, depression, and cognitive decline. Chronic pain alters the structure, chemistry, and connectivity of PFC in both humans and rodents. In this review, we broadly summarize the complexities of reported changes within both rodent and human PFC caused by pain and offer insight into potential pharmacological and nonpharmacological approaches for targeting PFC to treat chronic pain and pain-associated comorbidities. SIGNIFICANCE STATEMENT: Chronic pain is a significant unresolved medical problem causing detrimental changes to physiological, psychological, and behavioral aspects of life. Drawbacks of currently approved pain therapeutics include incomplete efficacy and potential for abuse producing a critical need for novel approaches to treat pain and comorbid disorders. This review provides insight into how manipulation of prefrontal cortex circuits could address this unmet need of more efficacious and safer pain therapeutics.

Efficacy of Transcranial Direct Current Stimulation on Pain Intensity and Functionality in Patients With Knee Osteoarthritis: A Systematic Review and Meta-analysis

OBJECTIVE

The aim of the study is to investigate whether transcranial direct current stimulation is superior to control groups or other interventions for pain relief and improving functionality in knee osteoarthritis patients.

METHODS

PubMed, the Physiotherapy Evidence Database, the Cochrane Library, ProQuest, and Scopus databases were searched from inception to July 2022 to identify randomized clinical trials. The main outcomes were subjective perception of pain intensity measured either with the visual analog scale or with the numeric rating scale; and the functionality, assessed with the Western Ontario and McMaster Universities Osteoarthritis Index. As secondary outcomes, pressure pain threshold, conditioned pain modulation, and its safety were evaluated.

RESULTS

We identified 10 randomized clinical trials (634 participants). The results showed an important effect favoring transcranial direct current stimulation for pain relief (mean difference = -1.1 cm, 95% confident interval = -2.1 to -0.2) and for improving functionality (standardized mean difference = -0.6, 95% confident interval = -1.02 to -0.26). There was also a significant improvement in pressure pain threshold (mean difference = 0.9 Kgf/cm 2 , 95% confident interval = 0.1 to 1.6). The certainty of evidence according to Grades of Recommendation Assessment, Development and Evaluation was generally moderate.

CONCLUSIONS

Our findings suggest that transcranial direct current stimulation is a safe treatment for reducing pain intensity, improving functionality, and the pressure pain thresholds in patients with knee osteoarthritis.

Transcranial Direct Current Stimulation for Knee Osteoarthritis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

The effects of transcranial direct current stimulation (tDCS) in the treatment of knee osteoarthritis (KOA) is still unclear. The objective is to evaluate the efficacy and safety of tDCS in improving symptoms in patients with KOA.

METHODS

The following electronic databases were searched for eligible randomized controlled trials (RCTs): PubMed, Embase, Web of Science, and the Cochrane Library. The search was performed from the inception dates to April 30, 2023. Data extraction and quality assessment were performed by two independent reviewers. Standard mean differences (SMDs) with 95% confidence intervals (95% CIs) for pooled data were calculated. A random-effects model was used for the data analyses. The primary outcomes were pain and physical function. Secondary outcomes included stiffness, mobility performance, quality of life, pressure pain tolerance, and plasma levels of brain-derived neurotrophic factor (BDNF).

RESULTS

This meta-analysis included 13 RCTs. tDCS was significantly associated with pain decrease compared with sham tDCS (SMD = -0.62, 95% CI -0.87 to -0.37, P < 0.00001). When comparing tDCS plus other non-tDCS with sham tDCS plus other non-tDCS, there was no longer a significant association with pain decrease (SMD = -0.45, 95% CI -1.08 to 0.17, P = 0.16). The changes in physical function were not significantly different between the tDCS and sham tDCS groups (SMD = -0.09, 95% CI -0.56 to 0.38, P = 0.71). When comparing tDCS plus other non-tDCS with sham tDCS plus other non-tDCS, there was still no significant association with improvement in physical function (SMD = -0.66, 95% CI -1.63 to 0.30, P = 0.18). There was no significant difference with improvement in stiffness (SMD = -0.21, 95% CI -0.77 to 0.34, P = 0.45), mobility performance (SMD = 4.58, 95% CI -9.21 to 18.37, P = 0.51), quality of life (SMD = -7.01, 95% CI -22.61 to 8.59, P = 0.38), and pressure pain tolerance (SMD = 0.30, 95% CI -0.09 to 0.69, P = 0.13). There was a statistically significant reduction in plasma levels of BDNF (SMD = -13.57, 95% CI -24.23 to -2.92, P = 0.01).

CONCLUSION

In conclusion, tDCS could significantly alleviate pain, but it might have no efficacy in physical function, stiffness, mobility performance, quality of life, and pressure pain tolerance among patients with KOA.

Transcranial Direct Current Stimulation for Orthopedic Pain: A Systematic Review with Meta-Analysis

(1) Background: Transcranial direct current stimulation (tDCS) appears to alleviate chronic pain via a brain-down mechanism. Although several review studies have examined the effects of tDCS on patients with chronic pain, no systematic review or meta-analysis has comprehensively analyzed the effects of tDCS on chronic orthopedic joint pain in one study. We aim to evaluate the effectiveness of tDCS for pain reduction in chronic orthopedic patients; (2) Methods: A comprehensive search of five electronic databases (Medline, Embase, Web of Science, CINAHL, and Cochrane) was performed. Only randomized controlled trials that compared tDCS with a control intervention were included. Eighteen studies met our inclusion criteria. We identified four categories of chronic orthopedic pain: knee (k = 8), lower back (k = 7), shoulder (k = 2), and orofacial pain (k = 1). Random effect models were utilized, and a sensitivity analysis was conducted in the presence of significant heterogeneity. Studies within each pain condition were further classified according to the number of treatment sessions: 1-5 sessions, 6-10 sessions, and >10 sessions.; (3) Results: Significant reductions in chronic orthopedic joint pain were observed following tDCS compared to controls for knee (g = 0.59, p = 0.005), lower back (g = 1.14, p = 0.005), and shoulder (g = 1.17, p = 0.020). Subgroup analyses showed pain reductions after 6-10 tDCS sessions for knee pain and after 1-5 and >10 sessions for lower back pain; (4) Conclusions: tDCS could be considered a potential stand-alone or supplemental therapy for chronic knee and lower back pain. The effectiveness of tDCS treatment varies depending on the number of treatment sessions. Our findings suggest the importance of implementing individualized treatment plans when considering tDCS for chronic pain conditions.

The effectiveness of home-based transcranial direct current stimulation on chronic pain: A systematic review and meta-analysis

Objective

As highlighted by the COVID-19 pandemic, identifying strategies for home-based patient management is crucial. As pain is highly prevalent and imposes significant burdens, interest in its remote management is steadily increasing. Transcranial Direct Current Stimulation (tDCS) seems promising in this context.

Methods

This systematic review and meta-analysis aimed to determine the effectiveness of home-based tDCS in pain management (PROSPERO, CRD42023452899). The extracted data included clinical conditions, interventions, comparators, outcome measures, adverse effects, and risk of bias; the Grading of Recommendations Assessment, Development and Evaluation (GRADE) assessment was carried out.

Results

12 records (9 randomized controlled trials [RCTs], 446 participants, 266 undergoing tDCS) were included in the systematic review. The meta-analysis showed that home-based tDCS might produce large and clinically relevant improvement in chronic pain intensity at the end of the intervention (standard mean difference [SMD] -0.95, 95% CI -1.34 to -0.56; p < 0.01; 404 participants, low certainty), as well as small clinically unimportant improvement at short-term follow-up (SMD -0.50, 95% CI -0.82 to -0.19; p < 0.01; 160 participants, moderate certainty). A subgroup analysis showed that it might clinically improve the chronic pain related to fibromyalgia and knee osteoarthritis. Moreover, home-based tDCS seems to modulate pressure pain threshold, heat pain threshold, and heat and cold tolerance at the end of the intervention. Notably, tDCS appeared to be generally safe, well-accepted and easily applied at home.

Conclusions

Low to moderate certainty evidence suggests that home-based self-administered tDCS is a safe and effective tool for managing various types of chronic pain. Further well-designed, large-scale RCTs are warranted.

Effectiveness of Transcranial Direct Current Stimulation in Knee Osteoarthritis: A Systematic Review and Meta-analysis of Randomized Sham-Controlled Trials

OBJECTIVE

The aim of the study is to assess the effectiveness of transcranial direct current stimulation in knee osteoarthritis.

METHODS

The study searched PubMed, Cochrane Library, Embase, and Scopus databases until August 3, 2023, and identified randomized controlled trials evaluating the effects of transcranial direct current stimulation in knee osteoarthritis whose outcomes using pain scores or functional scales. The selected randomized controlled trials were subjected to meta-analysis and risk of bias assessment.

RESULTS

Seven randomized controlled trials involving 488 patients were included in this meta-analysis. Compared with the control group, the transcranial direct current stimulation group exhibited significant improvement in pain scores after treatment (standardized mean difference = 1.03; 95% confidence interval: 0.70 to 1.35; n = 359; I2 = 46%), pain scores during follow-up (standardized mean difference = 0.83; 95% confidence interval: 0.21 to 1.45; n = 358; I2 = 86%), and Western Ontario and McMaster Universities Osteoarthritis scores after treatment (standardized mean difference = 4.76; 95% confidence interval: 0.16 to 9.53; n = 319; I2 = 74 % ), but Western Ontario and McMaster Universities Osteoarthritis scores during follow-up did not differ significantly between the groups (standardized mean difference = 0.06; 95% confidence interval: -0.2 to 0.32; n = 225; I2 = 0%).

CONCLUSIONS

Transcranial direct current stimulation is a promising therapy for knee osteoarthritis. Further investigation using large-scale, high-quality randomized controlled trials is necessary for optimal transcranial direct current stimulation approach in knee osteoarthritis.

OARSI year in review 2023: Rehabilitation and outcomes

OBJECTIVE

We systematically reviewed the literature to identify comparative studies of core treatments (exercise, education, or weight management), adjunct treatments (e.g. electrotherapeutical modalities, bracing), or multimodal treatments (core plus other treatments), for treating osteoarthritis (OA) complaints, published between 1 March 2022 and 1 March 2023.

DESIGN

We searched three electronic databases for peer-reviewed comparative studies evaluating core treatments, adjunct treatments, or multimodal treatments for OA affecting any joint, in comparison to other OA treatments. Two authors independently screened records. Methodological quality was assessed using the Physiotherapy Evidence Database (PEDro) scale. A narrative synthesis focusing on pain and function outcomes was performed in studies with a mean sample size of at least 46 participants per treatment arm.

RESULTS

33 publications (28 studies), 82% with PEDro ratings of good or excellent, were eligible for narrative synthesis: 23 studies evaluated knee OA; one knee OA or chronic low back pain; two knee or hip OA; one hip OA only; and one thumb OA. No studies identified a dose, duration or type of exercise that resulted in better pain or function outcomes. Core treatments generally showed modest benefits compared to no or minimal intervention controls.

CONCLUSIONS

Rehabilitation research continues to be focused on the knee. Most studies are not adequately powered to assess pain efficacy. Further work is needed to better account for contextual effects, identify treatment responder characteristics, understand treatment mechanisms, and implement guideline care.

The effects of anodal tDCS on pain reduction in people with knee osteoarthritis: A systematic review and meta-analysis

OBJECTIVES

To synthesise the literature on the efficacy of primary motor cortex anodal transcranial direct current stimulation (M1-a-tDCS), as a standalone or priming technique, for pain reduction in people with knee osteoarthritis (KOA).

METHODS

The systematic literature search was conducted in MEDLINE, CINAHL, Embase and CENTRAL according to PRISMA statement.

RESULTS

Fourteen studies involving 740 people with KOA were included. In the meta-analysis, six studies compared a-tDCS alone with sham stimulation, and five studies compared a-tDCS combined with other methods with sham stimulation. We found positive effect of a-tDCS alone on pain in KOA (standard mean difference (SMD) -0.52; 95% CI, -0.78 to -0.25; P=0.001; I2 = 69%). Further, a-tDCS with other treatments showed positive effect (SMD -1.23; 95% CI, -1.59 to -0.88; P<0.001; I2 = 48%) on pain in people with KOA. This evidence showed low certainty due to a high risk of bias and imprecision.

DISCUSSION AND CONCLUSION

A-tDCS could be considered as standalone and an adjunct treatment for pain reduction in people with KOA. Future randomised studies should address quality issues, including small sample size, to enhance the overall certainty of the findings.

SIGNIFICANCE

A-tDCS can be used as a standalone and adjunct treatment for KOA.

STUDY REGISTRATION

PROSPERO number CRD42021255114.

Feasibility, Acceptability, and Efficacy of Home-Based Transcranial Direct Current Stimulation on Pain in Older Adults with Alzheimer's Disease and Related Dementias: A Randomized Sham-Controlled Pilot Clinical Trial

Although transcranial direct current stimulation (tDCS) is emerging as a convenient pain relief modality for several chronic pain conditions, its feasibility, acceptability, and preliminary efficacy on pain in patients with Alzheimer's disease and related dementias (ADRD) have not been investigated. The purpose of this pilot study was to assess the feasibility, acceptability, and preliminary efficacy of 5, 20-min home-based tDCS sessions on chronic pain in older adults with ADRD. We randomly assigned 40 participants to active (n = 20) or sham (n = 20) tDCS. Clinical pain intensity was assessed using a numeric rating scale (NRS) with patients and a proxy measure (MOBID-2) with caregivers. We observed significant reductions of pain intensity for patients in the active tDCS group as reflected by both pain measures (NRS: Cohen's d = 0.69, p-value = 0.02); MOBID-2: Cohen's d = 1.12, p-value = 0.001). Moreover, we found home-based tDCS was feasible and acceptable intervention approach for pain in ADRD. These findings suggest the need for large-scale randomized controlled studies with larger samples and extended versions of tDCS to relieve chronic pain on the long-term for individuals with ADRD.

Self-administered transcranial direct current stimulation treatment of knee osteoarthritis alters pain-related fNIRS connectivity networks

Significance

Knee osteoarthritis (OA) is a disease that causes chronic pain in the elderly population. Currently, OA is mainly treated pharmacologically with analgesics, although research has shown that neuromodulation via transcranial direct current stimulation (tDCS) may be beneficial in reducing pain in clinical settings. However, no studies have reported the effects of home-based self-administered tDCS on functional brain networks in older adults with knee OA.

Aim

We used functional near-infrared spectroscopy (fNIRS) to investigate the functional connectivity effects of tDCS on underlying pain processing mechanisms at the central nervous level in older adults with knee OA.

Approach

Pain-related brain connectivity networks were extracted using fNIRS at baseline and for three consecutive weeks of treatment from 120 subjects randomly assigned to two groups undergoing active tDCS and sham tDCS.

Results

Our results showed that the tDCS intervention significantly modulated pain-related connectivity correlation only in the group receiving active treatment. We also found that only the active treatment group showed a significantly reduced number and strength of functional connections evoked during nociception in the prefrontal cortex, primary motor (M1), and primary somatosensory (S1) cortices. To our knowledge, this is the first study in which the effect of tDCS on pain-related connectivity networks is investigated using fNIRS.

Conclusions

fNIRS-based functional connectivity can be effectively used to investigate neural circuits of pain at the cortical level in association with nonpharmacological, self-administered tDCS treatment.

Efficacy of Home-Based Transcranial Direct Current Stimulation on Experimental Pain Sensitivity in Older Adults with Knee Osteoarthritis: A Randomized, Sham-Controlled Clinical Trial

Although transcranial direct current stimulation (tDCS) is encouraging regarding clinical pain intensity for individuals with knee osteoarthritis, very few studies have explored its impact on experimental pain sensitivity, which may hinder our understanding of underlying therapeutic mechanisms. The purpose of this study was to assess the efficacy of 15 home-based tDCS sessions on experimental pain sensitivity and explore its relationships with clinical pain intensity. We randomly assigned 120 participants to active tDCS (n = 60) and sham tDCS (n = 60). Quantitative sensory testing (QST) was used, including heat pain threshold and tolerance, pressure pain threshold, and conditioned pain modulation. Patients in the active tDCS group exhibited reduced experimental pain sensitivity as reflected by all QST measures at the end of treatment. Furthermore, correlations were observed between changes in clinical pain intensity and experimental pain sensitivity. These findings warrant further studies on tDCS and experimental pain sensitivity in patients with knee osteoarthritis and exploring the magnitude and sustainability of effects on a longer term.