Bilateral Motor Cortex tDCS Effects on Post-Stroke Pain and Spasticity: A Three Cases Study

Stretching exercises in managing spasticity: effectiveness, risks, and adjunct therapies

Spasticity is a component of upper motor neuron disorders and can be seen in neurological conditions like stroke and multiple sclerosis. Although the incidence rate of spasticity is unknown, it can put pressure on the health condition of those with spasticity, and there is no absolute effective way to control it. In the past, stretching exercises were an accessible tool for physical therapists to manage and control spasticity, but opinions on the optimal dose, aftereffects, and mechanism of effects were controversial. Therefore, this article tries to provide an overview of the effectiveness and risks of stretching exercises. Furthermore, there are several adjunct therapies, such as brain stimulation and botulinum injection, that can increase the effectiveness of a simple stretch by increasing cortical excitability and reducing muscle tone and their role is evaluated in this regard. The results of this study propose that several prospective and case studies have demonstrated the benefits of stretching to control spasticity, but it seems that other methods such as casting can be more effective than a simple stretch. Therefore, it is better to use stretching in combination with other therapeutic regimes to increase its effectivity of it.

Investigation into the Effectiveness of Combining Transcranial Direct Current Stimulation and Transcutaneous Electrical Nerve Stimulation as Treatment Options for Poststroke Shoulder Pain by Utilizing Functional Near-Infrared Spectroscopy

Objective

The aim of this study is to explore the therapeutic effects of transcranial direct current stimulation (tDCS) and transcutaneous electrical nerve stimulation (TENS) on post stroke shoulder pain (PSSP).

Methods

We enrolled 13 individuals in this study who underwent three different treatments in a random sequence: active tDCS+active TENS, active tDCS+sham TENS, and sham tDCS+active TENS. Each treatment was administered once, with a 3-day washout period between interventions. A blinded rater assessed the visual analog scale (VAS) scores, fNIRS readings, and sensory and pain tolerance thresholds of the participants before and after the stimulation.

Results

All three treatment methods can significantly alleviate PSSP (p<0.05). Compared with using tDCS alone, tDCS+TENS can significantly improve pain, with a statistically significant difference (p<0.05). In the 2KHz PTT task, the three treatment methods showed significant differences (p<0.05) in the mean oxygenated hemoglobin (HbO) levels in the false premotor cortex (PMC)/auxiliary motor area (SMA) before and after intervention.

Conclusion

The combination of tDCS+TENS can increase the pain-relieving impact on PSSP when compared to using tDCS alone. TENS may contribute an additional effect on the inhibitory systems influenced by tDCS that help reduce pain.

Clinical Registration Number

Registration website: https://www.chictr.org.cn. Registration date: 2022-02-25. Registration number: ChiCTR2200056970.

Exploring the Potential of Transcranial Direct Current Stimulation for Relieving Central Post-Stroke Pain: A Randomized Controlled Pilot Study

The potential of transcranial direct current stimulation (tDCS) as a non-invasive brain stimulation technique for treating pain has been studied. However, its effectiveness in patients with central post-stroke pain (CPSP) and the impact of lesion location remain unclear. This study investigated tDCS's pain reduction effects in patients with CPSP. Twenty-two patients with CPSP were randomized into the tDCS or sham groups. The tDCS group received stimulation of the primary motor cortex (M1) for 20 min, five times weekly, for two weeks, and underwent evaluations at baseline, immediately after the intervention, and one week after the intervention. The tDCS group had no significant improvement compared to the sham group in pain, depression, and quality of life. Nevertheless, significant changes were identified within the tDCS group, and the pain trends appeared to be influenced by the lesion location. These findings provide important insights into the use of tDCS in patients with CPSP, which could inform further research and development of pain treatment options.

MRI-Based Personalized Transcranial Direct Current Stimulation to Enhance the Upper Limb Function in Patients with Stroke: Study Protocol for a Double-Blind Randomized Controlled Trial

Transcranial direct current stimulation (tDCS) has been shown to have the potential to improve the motor recovery of the affected upper limbs in patients with stroke, and recently, several optimized tDCS methods have been proposed to magnify its effectiveness. This study aims to determine the effectiveness of personalized tDCS using brain MRI-based electrical field simulation and optimization, to enhance motor recovery of the upper limbs in the patients. This trial is a double-blind, randomized controlled trial in the subacute to chronic rehabilitation phase. Forty-two adult stroke patients with unilateral upper limb involvement will be randomly allocated to three groups: (1) personalized tDCS with MRI-based electrical field simulation and optimized stimulation, (2) conventional tDCS with bihemispheric stimulation of the primary motor cortex, and (3) sham tDCS. All three groups will undergo 10 intervention sessions with 30 min of 2-mA intensity stimulation, during a regular upper limb rehabilitation program over two weeks. The primary outcome measure for the motor recovery of the upper limb impairment is the Fugl-Meyer assessment for the upper extremity score at the end of the intervention, and the secondary measures include changes in the motor evoked potentials, the frequency power and coherence of the electroencephalography, performance in activities of daily living, and adverse events with a 1-month follow-up assessment. The primary outcome will be analyzed on the intention-to-treat principle. There is a paucity of studies regarding the effectiveness of personalized and optimized tDCS that considers individual brain lesions and electrical field characteristics in the real world. No feasibility or pivotal studies have been performed in stroke patients using brain MRI, to determine a lesion-specific tDCS simulation and optimization that considers obstacles in the segmentation and analysis of the affected brain tissue, such as ischemic and hemorrhagic lesions. This trial will contribute to addressing the effectiveness and safety of personalized tDCS, using brain MRI-based electrical field simulation and optimization, to enhance the motor recovery of the upper limbs in patients with stroke.

Effects of Non-Invasive Brain Stimulation on Post-Stroke Spasticity: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

In recent years, the potential of non-invasive brain stimulation (NIBS) for the therapeutic effect of post-stroke spasticity has been explored. There are various NIBS methods depending on the stimulation modality, site and parameters. The purpose of this study is to evaluate the efficacy of NIBS on spasticity in patients after stroke. This systematic review and meta-analysis was conducted according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. PUBMED (MEDLINE), Web of Science, Cochrane Library and Excerpta Medica Database (EMBASE) were searched for all randomized controlled trials (RCTs) published before December 2021. Two independent researchers screened relevant articles and extracted data. This meta-analysis included 14 articles, and all included articles included 18 RCT datasets. The results showed that repetitive transcranial magnetic stimulation (rTMS) (MD = −0.40, [95% CI]: −0.56 to −0.25, p < 0.01) had a significant effect on improving spasticity, in which low-frequency rTMS (LF-rTMS) (MD = −0.51, [95% CI]: −0.78 to −0.24, p < 0.01) and stimulation of the unaffected hemisphere (MD = −0.58, [95% CI]: −0.80 to −0.36, p < 0.01) were beneficial on Modified Ashworth Scale (MAS) in patients with post-stroke spasticity. Transcranial direct current stimulation (tDCS) (MD = −0.65, [95% CI]: −1.07 to −0.22, p < 0.01) also had a significant impact on post-stroke rehabilitation, with anodal stimulation (MD = −0.74, [95% CI]: −1.35 to −0.13, p < 0.05) being more effective in improving spasticity in patients. This meta-analysis revealed moderate evidence that NIBS reduces spasticity after stroke and may promote recovery in stroke survivors. Future studies investigating the mechanisms of NIBS in addressing spasticity are warranted to further support the clinical application of NIBS in post-stroke spasticity.

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.

The Concept, Development, and Application of a Home-Based High-Definition tDCS for Bilateral Motor Cortex Modulation in Migraine and Pain

Whereas, many debilitating chronic pain disorders are dominantly bilateral (e.g., fibromyalgia, chronic migraine), non-invasive and invasive cortical neuromodulation therapies predominantly apply unilateral stimulation. The development of excitatory stimulation targeting bilateral primary motor (M1) cortices could potentially expand its therapeutic effect to more global pain relief. However, this is hampered by increased procedural and technical complexity. For example, repetitive transcranial magnetic stimulation (rTMS) and 4 × 1/2 × 2 high-definition transcranial direct current stimulation (4 × 1/2 × 2 HD-tDCS) are largely center-based, with unilateral-target focus—bilateral excitation would require two rTMS/4 × 1 HD-tDCS systems. We developed a system that allows for focal, non-invasive, self-applied, and simultaneous bilateral excitatory M1 stimulation, supporting long-term home-based treatment with a well-tolerated wearable battery-powered device. Here, we overviewed the most employed M1 neuromodulation methods, from invasive techniques to non-invasive TMS and tDCS. The evaluation extended from non-invasive diffuse asymmetric bilateral (M1-supraorbital [SO] tDCS), non-invasive and invasive unilateral focal (4 × 1/2 × 2 HD-tDCS, rTMS, MCS), to non-invasive and invasive bilateral bipolar (M1-M1 tDCS, MCS), before outlining our proposal for a neuromodulatory system with unique features. Computational models were applied to compare brain current flow for current laboratory-based unilateral M1¹ and bilateral M1² HD-tDCS models with a functional home-based M1¹⁻² HD-tDCS prototype. We concluded the study by discussing the promising concept of bilateral excitatory M1 stimulation for more global pain relief, which is also non-invasive, focal, and home-based.