Anodal transcranial direct current stimulation for chronic pain in the elderly: a pilot study

Effects of tDCS on Foot Biomechanics: A Narrative Review and Clinical Applications

In recent years, neuro-biomechanical enhancement techniques, such as transcranial direct current stimulation (tDCS), have been widely used to improve human physical performance, including foot biomechanical characteristics. This review aims to summarize research on the effects of tDCS on foot biomechanics and its clinical applications, and further analyze the underlying ergogenic mechanisms of tDCS. This review was performed for relevant papers until July 2023 in the following databases: Web of Science, PubMed, and EBSCO. The findings demonstrated that tDCS can improve foot biomechanical characteristics in healthy adults, including proprioception, muscle strength, reaction time, and joint range of motion. Additionally, tDCS can be effectively applied in the field of foot sports medicine; in particular, it can be combined with functional training to effectively improve foot biomechanical performance in individuals with chronic ankle instability (CAI). The possible mechanism is that tDCS may excite specific task-related neurons and regulate multiple neurons within the system, ultimately affecting foot biomechanical characteristics. However, the efficacy of tDCS applied to rehabilitate common musculoskeletal injuries (e.g., CAI and plantar fasciitis) still needs to be confirmed using a larger sample size. Future research should use multimodal neuroimaging technology to explore the intrinsic ergogenic mechanism of tDCS.

Sling Exercise Can Drive Cortical Representation of the Transversus Abdominis and Multifidus Muscles in Patients With Chronic Low Back Pain

Objective

The transversus abdominis (TrA) and multifidus (MF) muscles are essential in preventing chronic low back pain (CLBP) recurrence by maintaining segmental stabilization and stiffness. Sling exercise is a high-level core stability training to effectively improve the activities of the TrA and MF muscles. However, the neural mechanism for sling exercise-induced neural plasticity change in the primary motor cortex (M1) remains unclear. This study aimed to investigate the role of sling exercise in the reorganization of the motor cortical representation of the TrA and MF muscles.

Methods

Twenty patients with CLBP and 10 healthy individuals were recruited. For map volume, area, the center of gravity (CoG) location (medial-lateral location and anterior-posterior location), and latency, two-way ANOVA was performed to compare the effects of groups (the CLBP-pre, CLBP-post, and healthy groups) and the two muscles (the TrA and MF muscles). The Visual Analog Scale (VAS), the Oswestry Disability Index (ODI), and postural balance stability were assessed at baseline and at the end of 2 weeks of sling exercise. Linear correlations between VAS or ODI and CoG locations were assessed by Pearson's correlation test.

Results

2 weeks of sling exercise induced both the anterior-medial (P < 0.001) and anterior-posterior (P = 0.025) shifts of the MF muscle representation at the left motor cortex in patients with CLBP. Anterior-medial (P = 0.009) shift of the TrA muscle representation at the right motor cortex was observed in patients with CLBP. The motor cortical representation of the two muscles in patients with CLBP after sling exercise (TrA: 2.88 ± 0.27 cm lateral and 1.53 ± 0.47 cm anterior of vertex; MF: 3.02 ± 0.48 cm lateral and 1.62 ± 0.40 cm anterior of vertex) closely resembled that observed in healthy individuals (TrA: 2.83 ± 0.48 cm lateral and 2.00 ± 0.43 cm anterior of vertex; MF: 2.94 ± 0.43 cm lateral and 1.77 ± 0.48 cm anterior of vertex). The VAS and the ODI were reduced following the sling exercise (VAS: P < 0.001; ODI: P < 0.001).

Conclusion

This study provides evidence that sling training can drive plasticity changes in the motor system, which corresponds with the reduction in pain and disability levels in patients with CLBP. This study was registered in the Chinese Clinical Trial Registry (Clinical Trial Registration Number: ChiCTR2100045904, http://www.chictr.org.cn/showproj.aspx?proj=125819).

Clinical Trial Registration

ChiCTR2100045904.

Relieving Chronic Musculoskeletal Pain in Older Adults Using Transcranial Direct Current Stimulation: Effects on Pain Intensity, Quality, and Pain-Related Outcomes

Introduction

Chronic pain is a significant health problem and is particularly prevalent amongst the elderly. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that has been proposed to reduce chronic pain. The aim of this study was to evaluate and compare the efficacy of active and sham tDCS in reducing pain in older individuals living with chronic musculoskeletal pain.

Materials and Methods

Twenty-four older individuals (mean age: 68 ± 7 years) suffering from chronic musculoskeletal pain were randomized to receive either anodal tDCS over the contralateral motor cortex (2 mA, 20 min; n = 12) or sham tDCS (20 min; n = 12) for five consecutive days. Pain logbooks were used to measure pain intensity. Questionnaires (McGill Pain Questionnaire, Brief Pain Inventory, Beck Depression Inventory [BDI], Beck Anxiety Inventory, Pain Catastrophizing Scale [PCS], and Margolis Pain Drawing and Scoring System [MPDSS]) were also used to assess pain in its globality.

Results

Analysis of pain logbooks revealed that active tDCS led to a reduction in daily average pain intensity (all p ≤ 0.04), while sham tDCS did not produce any change (p = 0.15). Between-group comparisons for change in pain intensity reduction between active and sham tDCS showed a trend during treatment (p = 0.08) which was significant at the follow-up period (p = 0.02). Active tDCS also improved scores of all questionnaires (all p ≤ 0.02), while sham tDCS only reduced MPDSS scores (p = 0.04). Between-group comparisons for the pain-related outcomes showed significant differences for BDI et PCS after the last tDCS session.

Conclusions

These results suggest that anodal tDCS applied over the primary motor cortex is an effective modality to decrease pain in older individuals. tDCS can also improve other key outcomes, such as physical and emotional functioning, and catastrophic thinking.

Brain stimulation: a therapeutic approach for the treatment of neurological disorders

Brain stimulation has become one of the most acceptable therapeutic approaches in recent years and a powerful tool in the remedy against neurological diseases. Brain stimulation is achieved through the application of electric currents using non-invasive as well as invasive techniques. Recent technological advancements have evolved into the development of precise devices with capacity to produce well-controlled and effective brain stimulation. Currently, most used non-invasive techniques are repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), whereas the most common invasive technique is deep brain stimulation (DBS). In last decade, application of these brain stimulation techniques has not only exploded but also expanded to wide variety of neurological disorders. Therefore, in the current review, we will provide an overview of the potential of both non-invasive (rTMS and tDCS) and invasive (DBS) brain stimulation techniques in the treatment of such brain diseases.

Vitamin D and Depressive Symptoms in Adults with Multiple Sclerosis: A Scoping Review

BACKGROUND

Vitamin D deficiency has been correlated with Multiple Sclerosis (MS) risk and disease activity. There is some controversy as to whether vitamin D could have an impact on depressive symptoms in people with MS (pwMS). The aim of this scoping review was to evaluate the association between vitamin D status and depressive symptoms in pwMS.

METHODS

We searched databases to include studies published up to March 2021 to provide an overview of the available evidence on the correlation between vitamin D status and depressive symptoms in pwMS. The eligibility criteria were as follows: studies evaluating the use of vitamin D measurement on depressive symptoms in patients suffering from MS, including randomized and non-randomized studies; studies written in English; and studies exploring an adult population over the age of 18.

RESULTS

Eleven studies met our inclusion criteria: two of them were abstracts only; the majority were cross-sectional studies; two were prospective longitudinal studies; one was a retrospective cohort study; and one was a randomized placebo-controlled trial (RCT). Of the eleven studies selected, seven showed a potential correlation between low vitamin D levels and depressive symptoms.

CONCLUSION

Future RCT studies should include patients with greater severity of depressive symptoms and should consider confounding factors such as sun exposure and seasonal variation of vitamin D.

Evaluation of the response to electric pulp testing in multiple sclerosis patients without a history of trigeminal neuralgia: a case-control study

Background

The importance of evaluating the pulpal threshold to electrical stimulation, as a side effect of probable neuropathy in Multiple Sclerosis (MS) patients is a novel issue. This study aimed to investigate electrical pulp test thresholds in MS patients without a history of trigeminal neuralgia compared to healthy individuals.

Methods

Sixty-nine maxillary central incisors, belonging to 34 relapsing-remitting MS patients, and 35 healthy individuals were included in this survey. The MS patients matched for intended variables, were 22–50 years old, had a more than 1-year history of MS, no history of trigeminal neuralgia and/or other neuropathy. The electric pulp sensibility test was performed on all samples. Electric pulp testing (EPT) results were recorded based on the pulp tester^’s grade that evoked a response. Data were analyzed with paired T-test, Mann-Whitney test, and Spearman correlation (P < 0.05).

Results

According to the results of this study, the mean values of response to EPT were 1.2 ± 0.5 and 1.8 ± 0.5 in MS patients and healthy individuals, respectively. The pulpal response to EPT between the two groups was significantly different (P < 0.0001).

Conclusions

MS patients showed a significantly reduced response to the electric pulp test in their maxillary central incisors in comparison to matched healthy persons.

Neuropathic Pain in the Elderly

Neuropathic pain due to a lesion or a disease of the somatosensory system often affects older people presenting several comorbidities. Moreover, elderly patients are often poly-medicated, hospitalized and treated in a nursing home with a growing risk of drug interaction and recurrent hospitalization. Neuropathic pain in the elderly has to be managed by a multidimensional approach that involves several medical, social and psychological professionals in order to improve the quality of life of the patients and, where present, their relatives.

Age as a Mediator of tDCS Effects on Pain: An Integrative Systematic Review and Meta-Analysis

Introduction: The transcranial direct current stimulation (tDCS) is a neuromodulatory technique with the potential to decrease pain scores and to improve chronic pain treatment. Although age is an essential factor that might impact the tDCS effect, most studies are solely conducted in adults. Therefore, the age limitation presents a critical research gap in this field and can be shown by only a handful of studies that have included other age groups. To examine the evidence upon the tDCS effect on pain scores on children, adolescents, or elderly, and indirectly, to infer the age-dependent impact on tDCS effects, we conducted a systematic review and meta-analysis.

Methods: A systematic review searching the following databases: PubMed, EMBASE, and Science Direct using the following search terms adapted according to MeSh or Entree: [(“Adolescent” OR “Children” OR “Elderly”) AND (“tDCS”) AND (“Pain” OR “Pain threshold”) AND (“dorsolateral prefrontal cortex” OR “Motor cortex)] up to April 20th, 2020. We retrieved 228 articles, 13 were included in the systematic review, and five studies with elderly subjects that had their outcomes assessed by pain score or pain threshold were included in the meta-analysis.

Results: For the analysis of pain score, 96 individuals received active stimulation, and we found a favorable effect for active tDCS to reduce pain score compared to sham (P = 0.002). The standardized difference was −0.76 (CI 95% = −1.24 to −0.28). For the pain threshold, the analysis showed no significant difference between active and sham tDCS. We reviewed two studies with adolescents: one study using anodal tDCS over the prefrontal cortex reported a reduction in pain scores. However, the second study reported an increase in pain sensitivity for the dorsolateral prefrontal cortex (DLPFC) stimulation.

Conclusion: Our findings suggest tDCS may reduce pain levels in the elderly group. Nevertheless, the small number of studies included in this review—and the considerable heterogeneity for clinical conditions and protocols of stimulation present—limits the support of tDCS use for pain treatment in elderly people. Larger studies on the tDCS effect on pain are needed to be conducted in elderly and adolescents, also evaluating different montages and electrical current intensity.

Effects of Transcranial Direct Current Stimulation on Knee Osteoarthritis Pain in Elderly Subjects With Defective Endogenous Pain-Inhibitory Systems: Protocol for a Randomized Controlled Trial

BACKGROUND

Knee osteoarthritis (OA) has been the main cause behind chronic pain and disabilities in the elderly population. The traditional treatment for knee OA pain currently concerns a number of combinations of pharmacological and nonpharmacological therapies. However, such combinations have displayed little effects on a significant group of subjects. In addition to this, pharmacological treatments often cause adverse effects, which limits their use on this population. Previous studies showed that chronic knee OA pain may be associated with maladaptive compensatory plasticity in pain-related neural central circuits indexed by a defective descending pain-inhibitory system. Transcranial direct current stimulation (tDCS) can revert some of these maladaptive changes, thus decreasing chronic pain sensation. Numerous studies have demonstrated that the use of anodal tDCS stimulation over the primary motor cortex (M1) has positive effects on chronic neuropathic pain. Yet, data on OA pain in elderly patients, including its effects on the endogenous pain-inhibitory system, remain limited.

OBJECTIVE

The objective of this study is to evaluate the efficacy of tDCS in reducing pain intensity caused by knee OA in elderly subjects with defective endogenous pain-inhibitory systems.

METHODS

We designed a randomized, sham-controlled, single-center, double-blinded clinical trial. Patients with knee OA who have maintained a chronic pain level during the previous 6 months and report a pain score of 4 or more on a 0-10 numeric rating scale (NRS) for pain in that period will undergo a conditioned pain modulation (CPM) task. Participants who present a reduced CPM response, defined as a decrease in NRS during the CPM task of less than 10%, and meet all of the inclusion criteria will be randomly assigned to receive 15 sessions of 2 mA active or sham tDCS for 20 minutes. A sample size of 94 subjects was calculated. The Brief Pain Inventory pain items will be used to assess pain intensity as our primary outcome. Secondary outcomes will include pain impact on functioning, mobility performance, quality of life, CPM, pressure pain threshold, touch-test sensory evaluation, and safety. Follow-up visits will be performed 2, 4, and 8 weeks following intervention. The data will be analyzed using the principle of intention-to-treat.

RESULTS

This study was approved by the institutional review board with the protocol number 1685/2016. The enrollment started in April 2018; at the time of publication of this protocol, 25 subjects have been enrolled. We estimate we will complete the enrollment process within 2 years.

CONCLUSIONS

This clinical trial will provide relevant data to evaluate if anodal tDCS stimulation over M1 can decrease chronic knee OA pain in elderly subjects with defective CPM. In addition, this trial will advance the investigation of the role of central sensitization in knee OA and evaluate how tDCS stimulation may affect it.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03117231; https://clinicaltrials.gov/ct2/show/NCT03117231 (Archived by WebCite at http://webcitation.org/73WM1LCdJ).

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR1-10.2196/11660.

Physical therapist decision-making in managing plantar heel pain: cases from a pragmatic randomized clinical trial

INTRODUCTION

Plantar heel pain (PHP) is a common condition managed by physical therapists that can, at times, be difficult to treat. Management of PHP is complicated by a variety of pathoanatomic features associated with PHP in addition to several treatment approaches with varying efficacy. Although clinical guidelines and clinical trial data support a general approach to management, the current literature is limited in case-specific descriptions of PHP management that addresses unique combinations of pathoanatomical, physical, and psychosocial factors that are associated with PHP. Purpose: The purpose of this case series is to describe physical therapist decision-making of individualized multimodal treatment for PHP cases presenting with varied clinical presentations. Treatment incorporated clinical guidelines and recent evidence including a combination of manual therapy, patient education, stretching, resistance training, and neurodynamic interventions. A common clinical decision-making framework was used to progress individualized treatment from a focus on symptom modulation initially to increased load tolerance of involved tissues and graded activity. In each case, patients met their individual goals and demonstrated clinically meaningful improvements in pain, function, and global rating of change that were maintained at the 1-2-year follow-up. Implications: This case series provides details of physical therapist management of a variety of PHP clinical presentations that can be used to complement clinical practice guidelines in the management of PHP.

Low back pain and disability in individuals with plantar heel pain

BACKGROUND

Lack of response to plantar heel pain (PHP) treatment may be related to unmanaged low back pain (LBP) and low back dysfunction, but a relationship between LBP and PHP has not been established. The purpose of this investigation was to compare the prevalence of LBP among individuals with and without PHP and to assess the association between low back disability and foot/ankle function.

METHODS

A cross-sectional study compared the prevalence and likelihood of LBP in individuals with (n=27) and without (n=27) PHP matched to age, sex, BMI, foot posture, and foot mobility. In individuals with PHP, correlations were examined between foot/ankle function using the foot and ankle ability measure (FAAM), low back disability using the Oswestry low back disability questionnaire (OSW), duration of PHP symptoms, body mass index (BMI), and age.

RESULTS

A greater percentage of individuals with PHP had LBP (74% versus 37% of controls, odds ratio=5.2, P=0.009) and higher levels of low back disability (17% higher OSW score than controls, P<0.001). In individuals with PHP, FAAM scores were correlated with OSW scores (ρ=-0.463, P=0.015), but not with duration of PHP symptoms, BMI, or age (P>0.150).

CONCLUSIONS

Individuals with PHP had a greater prevalence of LBP and higher low back disability that was correlated to reduced foot and ankle function. Treatment to address both local and proximal impairments, including impairments related to LBP, may be warranted to improve the management of PHP.

Can we improve pain and sleep in elderly individuals with transcranial direct current stimulation? - Results from a randomized controlled pilot study

Background

The prevalence of chronic pain and sleep disturbances substantially increases with age. Pharmacotherapy remains the primary treatment option for these health issues. However, side effects and drug interactions are difficult to control in elderly individuals.

Aims

The objective of this study was to assess the feasibility of conducting a randomized sham-controlled trial and to collect preliminary data on the efficacy of transcranial direct current stimulation (tDCS) to reduce pain and improve sleep in older adults suffering from chronic pain.

Methods

Fourteen elderly individuals (mean age 71±7 years) suffering from chronic pain and sleep complaints were randomized to receive either anodal tDCS, applied over the primary motor cortex (2 mA, 20 minutes), or sham tDCS, for 5 consecutive days. Pain was measured with visual analog scales, pain logbooks and questionnaires, while sleep was assessed with actigraphy, sleep diaries and questionnaires.

Results

There were no missing data for pain and sleep measures, except for actigraphy, that generated several missing data. Blinding was maintained throughout the study, for both the evaluator and participants. Active but not sham tDCS significantly reduced pain (P<0.05). No change was observed in sleep parameters, in both the active and sham tDCS groups (all P≥0.18).

Conclusion

The present study provides guidelines for the implementation of future tDCS studies in larger populations of elderly individuals. M1 anodal tDCS in this population appears to be effective to reduce pain, but not to improve sleep.

Long-Term Effects of Repeated Prefrontal Cortex Transcranial Direct Current Stimulation (tDCS) on Food Craving in Normal and Overweight Young Adults

BACKGROUND

The dorsolateral prefrontal cortex (DLPFC) plays an important role in the regulation of food intake. Several previous studies demonstrated that a single session of transcranial direct current stimulation (tDCS) of the DLPFC reduces food craving and caloric intake.

OBJECTIVES

We hypothesized that repeated tDCS of the right DLPFC cortex may exert long-term changes in food craving in young, healthy adults and that these changes may differ between normal and overweight subjects.

METHODS

Thirty healthy individuals who reported frequent food cravings without a prior history of eating disorders were initially recruited. Subjects were randomized into an ACTIVE group who received 5 days of real tDCS (20 minutes, anode right-cathode left montage, 2 mA with current density kept at 0.06 mA/cm2, 1 min ramp-up/ramp-down), and a SHAM group, who received one day of real tDCS, on the first day (same parameters), followed by 4 days of sham tDCS. Food craving intensity was examined by Food Craving Questionnaires State and Trait and Food Craving Inventory before, during, (5-days) and one month (30-days) after tDCS.

RESULTS

Single session of tDCS significantly reduced the intensity of current food craving (FCQ-S). Five days of active tDCS significantly reduced habitual experiences of food craving (FCQ-T), when compared to baseline pre-stimulation levels. Furthermore, both current (FCQ-S) and habitual craving (FCQ-T) were significantly reduced 30 days after active tDCS, while sham tDCS, i.e. a single tDCS session did not have significant effects. Also, active tDCS significantly decreased craving for fast food and sweets, and to a lesser degree for fat, while it did not have significant effects on craving for carbohydrates (FCI). There were no significant differences between individual FCQ-T subscales (craving dimensions) after 5 or 30 days of either sham or active tDCS. Changes in craving were not significantly associated with the initial weight, or with weight changes 30 days after the stimulation in the subjects.

CONCLUSIONS

The results confirm earlier findings that single session of tDCS has immediate effects in reducing food craving. They also show that repeated tDCS over the right DLPFC may increase the duration of its effects, which may be present 30 days after the stimulation. These results support further investigation of the use of tDCS in obesity.