Comparison of bihemispheric and unihemispheric M1 transcranial direct current stimulations during physical therapy in subacute stroke patients: A randomized controlled trial

Neuromodulation technologies improve functional recovery after brain injury: From bench to bedside

Spontaneous recovery frequently proves maladaptive or insufficient because the plasticity of the injured adult mammalian central nervous system is limited. This limited plasticity serves as a primary barrier to functional recovery after brain injury. Neuromodulation technologies represent one of the fastest-growing fields in medicine. These techniques utilize electricity, magnetism, sound, and light to restore or optimize brain functions by promoting reorganization or long-term changes that support functional recovery in patients with brain injury. Therefore, this review aims to provide a comprehensive overview of the effects and underlying mechanisms of neuromodulation technologies in supporting motor function recovery after brain injury. Many of these technologies are widely used in clinical practice and show significant improvements in motor function across various types of brain injury. However, studies report negative findings, potentially due to variations in stimulation protocols, differences in observation periods, and the severity of functional impairments among participants across different clinical trials. Additionally, we observed that different neuromodulation techniques share remarkably similar mechanisms, including promoting neuroplasticity, enhancing neurotrophic factor release, improving cerebral blood flow, suppressing neuroinflammation, and providing neuroprotection. Finally, considering the advantages and disadvantages of various neuromodulation techniques, we propose that future development should focus on closed-loop neural circuit stimulation, personalized treatment, interdisciplinary collaboration, and precision stimulation.

Intra-rater reliability and validity of neuro-mobinavigation: A mobile app and laser-guided system of motor HotSpot localization

BACKGROUND

Optimal transcranial magnetic stimulation (TMS) efficacy depends on precise coil placement and orientation, as even minor deviations can significantly change the excitation evoked when stimulating the primary motor cortex (M1). To compare the intra-rater reliability of a novel method for consistent TMS coil orientation over a predetermined hotspot in M1, and to benchmark its accuracy against non-navigated method.

NEW METHOD

A three-step method was employed. First, a laser-guided-system stabilized head position. Second, a mobile-app monitored coil tilt and orientation. Finally, coil position was marked on participant's head cap for visual reference for both methods. Twenty-nine healthy-participants underwent six TMS blocks of 20 pulses each. Six experimental blocks, alternating between non-navigated-TMS and Neuro-Mobinavigated-TMS, to investigate the parameters of motor evoked potential (MEP). The experimental blocks were quasi-randomized with a five-minute interval.

RESULTS AND COMPARISON WITH EXISTING METHOD(S)

The novel method demonstrated excellent intra-rater reliability (ICC = 0.95, 95 % CI: 0.90-0.97) compared to moderate intra-rater reliability of the non-navigated TMS (ICC = 0.73, 95 % CI: 0.57-0.85) for MEP peak amplitude. Repeated measures ANOVA for novel-method showed consistent peak amplitude across three blocks (p = 0.078), non-navigated TMS exhibited significant variations (p < 0.0001). Wilcoxon signed rank test revealed significantly higher mean peak amplitudes for the novel method (1.02 ± 0.74) compared to non-navigated TMS (0.78 ± 0.61) (p < 0.001), small effect size (r = 0.35).

CONCLUSIONS

Neuro-Mobinavigation is superior to non-navigated method and provides a reliable and cost-effective alternative for MEP studies where gold standard neuronavigation is not available.

Efficacy of anodal transcranial direct current stimulation for upper extremity function after ischemic stroke: A systematic review of parallel randomized clinical trials

BACKGROUND

Although existing studies had shown therapeutic effects of transcranial direct current stimulation (tDCS) on upper limb dysfunction after stroke, previous systematic reviews had mostly provided general analyses on the polarity of tDCS and the type of stroke, with inconsistent results. We aimed to determine the efficacy of anodal transcranial direct current stimulation in enhancing upper extremity function following ischemic stroke.

METHODS

A comprehensive search was conducted across a variety of databases, spanning from their inception to March 15th, 2024.The focus was on parallel randomized clinical trials published that explored the impact of anodal transcranial direct current stimulation on upper extremity function in ischemic stroke patients. Data extraction and quality assessment were conducted independently by two reviewers. The Cochrane Risk of Bias Tool was utilized to assess the risk of bias in the included studies.

RESULTS

A total of 19 studies involving 1032 participants were included in the analysis. The pooled results of these studies indicated that anodal transcranial direct current stimulation had a positive impact on the Fugl-Meyer Assessment Upper Extremity, Wolf Motor Function Test, Resting Motion Threshold, and Barthel Index Score in ischemic stroke patients with upper extremity dysfunction. Follow-up data suggested the potential long-term efficacy of anodal transcranial direct current stimulation in ischemic stroke. Reported adverse reactions indicated that anodal transcranial direct current stimulation was relatively safe for stroke patients.

CONCLUSIONS

Anodal transcranial direct current stimulation is an effective intervention and relatively safe and effective intervention for improving upper extremity function in ischemic stroke patients.

A Literature Review on Optimal Stimulation Parameters of Transcranial Direct Current Stimulation for Motor Recovery After Stroke

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulatory technique with potential in stroke rehabilitation by modulating cortical excitability. However, the optimal parameters, including electrode placement, current intensity, stimulation duration, and electrode size, remain poorly understood, and the interactions among these factors contribute to mixed results in motor recovery post-stroke. This review explores the various stimulation parameters and their impact on enhancing corticospinal excitability (CSE) and motor function recovery. Different electrode placement (montages), such as anodal, cathodal, and bi-hemispheric stimulation, have demonstrated varying effectiveness in restoring motor function. Bihemispheric stimulation demonstrated a larger effect size compared to other unihemispheric (anodal or cathodal) stimulation; however, its relative superiority remains inconclusive. Inter-individual anatomical variations, such as skull thickness, lesion location, and cortical atrophy, can affect tDCS outcomes, highlighting the need for personalized electrode placement guided by computational modeling based on brain imaging. Furthermore, stimulation intensity, typically 1-2 mA, exhibited nonlinear effects on CSE, contrasting with the dose-response relationships observed in earlier studies. Stimulation duration is also critical, with evidence suggesting that prolonged stimulation may reverse excitability-enhancing effects beyond a certain threshold. While smaller electrodes enhance focality, an appropriately sized electrode is necessary to effectively modulate electrical activity in the target region, with evidence suggesting a dose-response relationship between electrode size and motor recovery. Overall, the interplay among these parameters underscores the need for personalized and optimized tDCS protocols to achieve consistent motor recovery in stroke patients. Future research should focus on refining these parameters to maximize the therapeutic benefits of tDCS.

Transcranial Direct Current Stimulation for Improving Balance in Healthy Older Adults and Older Adults with Stroke: A Scoping Review

Background/Objectives: Age-related decline in balance and postural control is common in healthy elders and is escalated in aging adults with stroke. Transcranial direct current stimulation (tDCS) has emerged as one of the promising brain stimulations adjoining therapeutic exercise to enhance the recovery of balance and motor functions in persons with and without neurological disorders. This review aims to summarize and compare the available evidence of the tDCS on improving balance in the older adults without neurological disorders and the older adults with stroke. Methods: The Ovid (Medline) database was searched from its inception through to 06/15/2024 for randomized controlled trials investigating tDCS for improving balance in older adults with and without stroke. Results: Overall, 20 appropriate studies (including 271 stroke subjects and 259 healthy older adults) were found. The data indicate mixed results of tDCS for improving balance in older adults with and without stroke. Conclusions: Based on current research evidence, we have not found a specific tDCS protocol that is more effective than other tDCS protocols for improving balance and postural control in healthy older adults and older adults with stroke. Further research should explore the ideal tDCS approach, possibly in conjunction with standard interventions, to optimize postural control and balance in healthy older adults and older adults with stroke.

Exploring the Prospects of Transcranial Electrical Stimulation (tES) as a Therapeutic Intervention for Post-Stroke Motor Recovery: A Narrative Review

INTRODUCTION

Stroke survivors often have motor impairments and related functional deficits. Transcranial Electrical Stimulation (tES) is a rapidly evolving field that offers a wide range of capabilities for modulating brain function, and it is safe and inexpensive. It has the potential for widespread use for post-stroke motor recovery. Transcranial Direct Current Stimulation (tDCS), Transcranial Alternating Current Stimulation (tACS), and Transcranial Random Noise Stimulation (tRNS) are three recognized tES techniques that have gained substantial attention in recent years but have different mechanisms of action. tDCS has been widely used in stroke motor rehabilitation, while applications of tACS and tRNS are very limited. The tDCS protocols could vary significantly, and outcomes are heterogeneous.

PURPOSE

the current review attempted to explore the mechanisms underlying commonly employed tES techniques and evaluate their prospective advantages and challenges for their applications in motor recovery after stroke.

CONCLUSION

tDCS could depolarize and hyperpolarize the potentials of cortical motor neurons, while tACS and tRNS could target specific brain rhythms and entrain neural networks. Despite the extensive use of tDCS, the complexity of neural networks calls for more sophisticated modifications like tACS and tRNS.

Transcranial direct current stimulation in physical therapy treatment for adults after stroke: A systematic review

BACKGROUND

Stroke is a clinical syndrome that can cause neurological disorders due to a reduction or interruption in the blood flow at the brain level. Transcranial direct current stimulation (TDCS) is a non-invasive electrotherapy technique with the ability to modulate the function of nervous tissue.

OBJECTIVE

The aim of this review is to analyze the effects derived from the application of the TDCS for post-stroke patients on functionality and mobility.

METHODS

The data search was conducted in PubMed, PEDro, Cochrane Library, Web of Science and Scopus between July and August 2023. The search focused on randomized clinical trials conducted in the period of 2019-2023, and according to the selection criteria, seven studies were obtained.

RESULTS

The results found are mainly focused on the analysis of the scales Fugl-Meyer Assessment for Upper Extremity and Wolf Motor Function Test.

CONCLUSION

The application of TDCS presents benefits in post-stroke individuals on functionality, mobility and other secondary studied variables.