ArticlePDF Available

Using clinical and robotic assessment tools to examine the feasibility of pairing tDCS with upper extremity physical therapy in patients with stroke and TBI: A consideration-of-concept pilot study

Authors:

Abstract and Figures

Background: Transcranial direct current stimulation (tDCS) may provide a safe, non-invasive technique for modulating neural excitability during neurorehabilitation. Objective: 1) Assess feasibility and potential effectiveness of tDCS as an adjunct to standard upper extremity (UE) physical therapy (PT) for motor impairments resulting from neurological insult. 2) Determine sustainability of improvements over a six month period. Methods: Five participants with chronic neurologic insult (stroke or traumatic brain injury > 6 months prior) completed 24 sessions (40 minutes, three times/week) of UE-PT combined with bihemispheric tDCS delivered at 1.5 mA over the motor cortex during the first 15 minutes of each PT session. Outcomes were assessed using clinical (UE Fugl-Meyer, Purdue Pegboard, Box and Block, Stroke Impact Scale) and robotic (unimanual and bimanual motor control) measures. Change in scores and associated effects sizes from Pre-test to Post-test and a six month Follow-up were calculated for each participant and group as a whole. Results: Scores on UE Fugl-Meyer, Box and Block, Purdue Pegboard, Stroke Impact Scale, and robotic measures improved from Pre- to Post-test. Improvements on UE Fugl-Meyer, Box and Block, and robotic measures were largely sustained at six months. Conclusions: Combining bihemispheric tDCS with UE-PT in individuals with neurological insult warrants further investigation.
Robotic Assessment. A, Individual seated at the KINARM End-Point Lab (BKIN Technologies, Kingston, Ontario, Canada). While sitting in a modified wheelchair base that can be raised and lowered with a hydraulic system, participants grasp two handles linked to robotic motors that can apply loads to either hand. Small discs are mounted underneath each handle to provide the hands with gravitational support. A video monitor and semitransparent mirror located above the hands are used to project visual targets onto the same plane as the hands. B,C, Hand paths and hand-speed profiles of Participant 5 during performance of the visually guided reaching task with the affected left hand (left half) and less affected right hand (right half) at Pre-test (B) and Post-test (C). Hand paths (center row) depict each reaching movements from the central target out to the four peripheral targets (first and third plots) and from the peripheral targets back to the central target (second and fourth plots). The hand-speed profiles (top and bottom rows) correspond to reaching movements to and from the closest peripheral target in each plot. Each line on the graph represents a single trial. D, Overhead reproduction of Participant 2 (right upper extremity affected) performing the object hit task. Participants use paddles (5 cm) attached to each hand to hit away as many balls as possible as they move towards them from the top of the screen. E, F, Performance of Participant 2 on the object hit task at Pre-test (E) and Post-test (F). Balls move along 10 vertical paths (columns) with 30 balls (rows) in each path for a total of 300 balls. Blue areas represent hits with the left hand (less affected) and red areas represent hits with the right hand (affected). White areas represent misses. At Pre-test, Participant 2 frequently uses her left hand to hit balls on the right side of the screen (E), whereas hand and use is more symmetrical at Post-test (F). This is shown measured by the hand transition parameter (dashed line), which is on the right during the Pre-test and relatively central during the Post-test.
… 
Content may be subject to copyright.
A preview of the PDF is not available
... 57 At the motor impairment level, the FMA was commonly used. 41,42,48,51,53 Goniometry 34,35,49 and torque-controlled passive extension 37 helped assess changes in wrist and elbow ranges of motion. In addition, kinematic motor performance outcomes including speed, reaching path straightness, and accuracy helped quantify motor impairment. ...
... The WMFT was commonly used [40][41][42]56 across the different studies. Dexterity was measured by using the BBT, 46,48,51 Purdue Pegboard Test, 43 TEMPA, 37,52 and Jebsen Taylor Hand Function test 48 in different studies. Limitations in ADL performance were also quantified using the FIM, 36,53 the CHART, 36 Frenchay Arm Test, 56 and the ARAT. ...
... 12 Retention of improvements in performance noted at the end of the intervention denote motor learning. However, only 10 [36][37][38][39]41,44,51,52,55,56 studies included any form of retention testing. Amongst these studies, the timing of testing varied widely. ...
Article
Background Traumatic brain injury (TBI) is a leading cause of adult morbidity and mortality. Individuals with TBI have impairments in both cognitive and motor domains. Motor improvements post-TBI are attributable to adaptive neuroplasticity and motor learning. Majority of the studies focus on remediation of balance and mobility issues. There is limited understanding on the use of interventions for upper limb (UL) motor improvements in this population. Objective We examined the evidence regarding the effectiveness of different interventions to augment UL motor improvement after a TBI. Methods We systematically examined the evidence published in English from 1990–2020. The modified Downs and Black checklist helped assess study quality (total score: 28). Studies were classified as excellent: 24–28, good: 19–23, fair: 14–18, and poor: ≤13 in quality. Effect sizes helped quantify intervention effectiveness. Results Twenty-three studies were retrieved. Study quality was excellent (n = 1), good (n = 5) or fair (n = 17). Interventions used included strategies to decrease muscle tone (n = 6), constraint induced movement therapy (n = 4), virtual reality gaming (n = 5), non-invasive stimulation (n = 3), arm motor ability training (n = 1), stem cell transplant (n = 1), task-oriented training (n = 2), and feedback provision (n = 1). Motor impairment outcomes included Fugl-Meyer Assessment, Modified Ashworth Scale, and kinematic outcomes (error and movement straightness). Activity limitation outcomes included Wolf Motor Function Test and Motor Activity Log (MAL). Effect sizes for majority of the interventions ranged from medium (.5-.79) to large (≥.8). Only ten studies included retention testing. Conclusion There is preliminary evidence that using some interventions may enhance UL motor improvement after a TBI. Answers to emergent questions can help select the most appropriate interventions in this population.
... Furthermore, different parts of the brain regions including prefrontal cortex and motor cortex are stimulated to treat TBI impairments such as cognitive and motor problems. For instance, among people with TBI, the prefrontal area and the dorsolateral prefrontal cortex (either left-or right-side DLPFC) was stimulated to treat non-motor (e.g., depression, attention, memory) impairment [32,34] while motor impairment was usually treated by stimulating the motor cortex [30,37,38]. Similarly, TMS has been reported to improve motor and behavioural functions after stimulating the cerebellum, motor cortex/M1, frontal (DLPFC) and/or temporal regions in TBI [39][40][41]; cognitive functions (e.g., working memory and executive function) after stimulating the DLPFC, frontotemporal, or posterior parietal cortex [41][42][43][44]; and psychological problems (e.g., posttraumatic stress disorder) after stimulating the DLPFC [40,43,45,46]. ...
... The funnel plot result did not show significant asymmetry (Figure 3). [38,40,[55][56][57][58][59][60][61]. ...
... The effect of non-invasive brain stimulation (NIBS) on memory; (a) summary table for each study; (b) forest plot for each study[38,[55][56][57][58][59]61]. ...
Article
Full-text available
This systematic review and meta-analysis aggregated and examined the treatment effect of non-invasive brain stimulation (NIBS) (transcranial direct current stimulation and transcranial magnetic stimulation) on cognitive functions in people with traumatic brain injury (TBI). A systematic search was conducted using databases (PubMed, Web of Science, Scopus, PsycINFO, EMBASE) for studies with keywords related to non-randomized and randomized control trials of NIBS among people with TBI. Nine out of 1790 NIBS studies with 197 TBI participants (103 active vs. 94 sham) that met the inclusion and exclusion criteria of the present study were finally selected for meta-analysis using Comprehensive Meta-Analysis software (version 3). Results showed that the overall effect of NIBS on cognition in people with TBI was moderately significant (g = 0.304, 95% CI = 0.055 to 0.553) with very low heterogeneity across studies (I2 = 0.000, Tau = 0.000). Specifically, significant and marginally significant moderate effect sizes were found for cognitive sub-domains including attention, memory, and executive function. The present findings suggest that NIBS is moderately effective in improving cognitive functions among people with TBI. In particular, NIBS may be used as an alternative and/or an adjunct treatment to the traditional approach in rehabilitating cognitive functions in people with TBI.
... In 2014, Middleton et al. [39] conduct a study, which enrolled 5 patients with chronic neurologic insult, which stroke or traumatic brain injury more than 6 months. Participants were requested to complete 24 courses (40 minutes, three times a week) of upper limb physical therapy (UE-PT) and to perform bihemispheric tDCS on the motor cortex at a speed of 1.5 MA in the first 15 minutes of each course. ...
... (2) A safe, noninvasive technique [39]. ...
... (3) Stimulation was well-tolerated [39]. ...
Article
Full-text available
The rapid progress of the combination of medicine and engineering provides better chances for the clinical treatment and healthcare engineering. Traumatic brain injury (TBI) and its related symptoms have become a major global health problem. At present, these techniques has been widely used in the rehabilitation of TBI. In this review article, we summarizes the progress of the combination of medicine and industry in the rehabilitation of traumatic brain injury in recent years, mainly from the following aspects: artificial intelligence (AI), brain-computer interfaces (BCI), noninvasive brain stimulation (NIBS), and wearable-assisted devices. We believe the summary of this article can improve insight into the combination of medicine and industry in the rehabilitation of traumatic brain injury.
... Outcomes assessed using Fugl-Meyer Assessment for upper extremity, Box and Block test, Stroke Impact Scale and robotic measures significatively enhanced after treatment. Increases recorded were confirmed six months later 58 . In 2016 Sacco et al 59 investigated the application of tDCS on the recovery of divided attention in patients with severe brain injury. ...
Article
Objective: This review aimed to evaluate and summarize the current knowledge about the non-pharmacological neurological stimulation (NPNS) in patients with severe brain injuries (SBI). The approaches we analyzed included sensory stimulation, music therapy, virtual reality, transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS). Materials and methods: We performed a review following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) standards. The key words used for the search across electronic databases such as PubMed and the Cochrane Library were "brain injury" or "coma" or "vegetative state" and "neurological stimulation" or "sensory stimulation" or "music therapy" or "virtual reality" or "transcranial direct current stimulation" or "transcranial magnetic stimulation". Results: 38 studies matched the inclusion criteria. These articles were categorized into five clusters: sensory stimulation, music therapy, virtual reality, transcranial direct current stimulation and transcranial magnetic stimulation. Hence, a concise summary of each study was made up, including study population characteristics, type of non-pharmacological neurological stimulation, neurological clinical outcomes or neuroimaging outcomes. Conclusions: Overall, all the non-pharmacological approaches to neurological stimulation in patients with SBI seem to be innovative and promising. Further randomized clinical trials, including a wide range of patients, will be necessary to definitely validate these methods and develop standardized protocols shared in the scientific community.
... 57,58 Several studies demonstrated that TMS and tDCS can improve attention, working memory, and motor performance after TBI. [59][60][61][62] This has important implications in the treatment of motor and cognitive deficits because it provides further evidence that chronic electrical stimulation may be a feasible method to promote recovery. While early evidence suggests invasive stimulation likely results in a greater level of behavioral improvement, 39 more research directly comparing the effectiveness and the adverse effect profile of the 2 treatment modalities is needed. ...
Article
We aim to provide a comprehensive review of the current scientific evidence supporting the use of invasive neurostimulation in the treatment of deficits associated with traumatic brain injury (TBI), as well as to identify future directions for research and highlight important questions that remain unaddressed. Neurostimulation is a treatment modality with expanding applications in modern medical practice. Targeted electrical stimulation of specific brain regions has been shown to increase synaptogenesis and enhance structural reorganization of neuronal networks. This underlying therapeutic effect might be of high value for patients suffering from TBI because it could modulate neuronal connectivity and function of areas that are partially or completely spared after injury. The current published literature exploring the application of invasive neurostimulation for the treatment of functional deficits associated with TBI is scarce but promising. Rodent models have shown that targeted stimulation of the hippocampus or connecting structures can result in significant cognitive recovery, while stimulation of the motor cortex and deep cerebellar nuclei is associated with motor improvements. Data from clinical studies are extremely limited; single-patient reports and case series found neurostimulation to be effective in relieving motor symptoms, improving visuospatial memory, and supporting emotional adjustment. Looking forward, it will be important to identify stimulation targets and paradigms that can maximize improvement over multiple functional domains. It will also be important to corroborate the observed behavioral improvements with histological, electrophysiological, and radiological evidence. Finally, the impact of biological variables such as sex and age on the treatment outcomes needs to be explored.
... 38 2. Robotic motor assessment tools are being developed as well that not only do an assessment but also quantify objectively over a long period this will enhance assessments even more so than in-person in the future. 39,40 The neurological examination requires some special tools depending on the patient's needs. Technological advancement has met some of these challenges, eg, physicians use different mobile apps to perform examinations in neuro-ophthalmology. ...
Article
Full-text available
Virtual care is here to stay. The explosive expansion of telehealth caused by the SARS-CoV-2 pandemic is more than a necessary measure of protection. The key drivers of this transition in healthcare delivery to a virtual setting are changes in patient behavior and expectations and societal attitudes, and prevailing technologies that are impossible to ignore. The younger population - Generation Z - is increasingly connected and mobile-first. We are heading to a world where we expect to see healthcare in general and neurology, in particular, delivered virtually. The medical community should prepare for this overhaul; proper implementation of virtual care from the ground up is the need of the hour. In an era of virtualization, it is up to the medical community to ensure a well-informed patient population, overcome cultural differences and build digital infrastructure with enhanced access and equity in care delivery, especially for the aging neurological patient population, which is not technologically savvy. Virtual care is a continuum of care that needs deeper integration at systematic levels. The design principles of a patient’s journey need to be incorporated while simultaneously placing physician satisfaction with a better user experience at the center of implementation. In this paper, we discuss common challenges and pitfalls of virtual care implementation in neurology - logistical, technical, medicolegal, and those faced in incorporating health and medical education into virtual care - intending to provide solutions and strategies.
... In testing chronic stroke patients, many prior studies reported transient and sustained treatment effects of tDCS protocols on unilateral paretic arm functions [22,97,98], whereas potential tDCS effects on bimanual motor functions are still insufficient. A limited number of studies revealed that bihemispheric tDCS in addition to conventional physical therapy improved interlimb coordinative skills in patients with stroke [99,100]. ...
Article
Full-text available
Executing voluntary motor actions in the upper extremities after a stroke is frequently challenging and frustrating. Although spontaneous motor recovery can occur, reorganizing the activation of the primary motor cortex and supplementary motor area takes a considerable amount of time involving effective rehabilitation interventions. Based on motor control theory and experience-dependent neural plasticity, stroke protocols centered on bimanual movement coordination are generating considerable evidence in overcoming dysfunctional movements. Looking backward and forward in this comprehensive review, we discuss noteworthy upper extremity improvements reported in bimanual movement coordination studies including force generation. Importantly, the effectiveness of chronic stroke rehabilitation approaches that involve voluntary interlimb coordination principles look promising.
... Acupuncture, a method used in TCM for over 2,000 years, involves the stimulation of specifi c meridian points, or acupoints, by inserting fi ne needles on the skin. [39][40][41] The goal of applying acupuncture is to enhance health through restoring the strength and quality of the fl ow of Qi, which is defi ned as the vital force or energy that fl ows along channels called meridians. 41 Overall, improvements in adults with ABI have been seen in general functionality, motor function, and posttraumatic headache. ...
... Stimulation intensity was set to 1.5 mA and was delivered for 15 minutes via saline-soaked sponge electrodes (size: 5x5cm; surface area: 25 cm 2 ; current density: 0.06 mA/cm 2 ), connected to aDC stimulator (tDCS Stimulator Clinical Version, TCT research Limited, Hong-Kong), using a 10 seconds ''on" and ''off" ramping. The configuration of the above parameters was based on a previous study that combined tDCS with physical therapy in patients (Middleton et al., 2014). The size of the anode electrode and stimulation intensity were based on methods detailed previously (Ho et al., 2016). ...
Article
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that may improve motor learning. However, the long-term effects of tDCS have not been explored, and the ecological validity of the evaluated tasks was limited. To determine whether 20 sessions of tDCS over the primary motor cortex (M1) would enhance the performance of a complex life motor skill, i.e., typing, in healthy young adults. Healthy young adults (n=60) were semi-randomly assigned to 3 groups: the tDCS group (n=20) received anodal tDCS over M1; the SHAM group (n=20) received sham tDCS, both while performing a typing task; and the Control group (CON, n=20) only performed the typing task. Typing speed and errors at maximum (mTT) and submaximal (iTT) speeds were measured before training, and after 10 and 20 sessions of tDCS. Every subject increased maximum typing speed after 10 and 20 tDCS sessions, with no significant differences (p> 0.05) between the groups. The number of errors at submaximal rates decreased significantly (p< 0.05) by 4% after 10 tDCS sessions compared with the 3% increase in the SHAM and the 2% increase in the CON groups. Between the 10th and 20th tDCS sessions, the number of typing errors increased significantly in all groups. While anodal tDCS reduced typing errors marginally, such performance-enhancing effects plateaued after 10 sessions without any further improvements in typing speed. These findings suggest that long-term tDCS may not have functionally relevant effects on healthy young adults’ typing performance.
Article
Full-text available
Background: Since a stroke can impair bimanual activities, enhancing bimanual cooperation through motor skill learning may improve neurorehabilitation. Therefore, robotics and neuromodulation with transcranial direct current stimulation (tDCS) are promising approaches. To date, tDCS has failed to enhance bimanual motor control after stroke possibly because it was not integrating the hypothesis that the undamaged hemisphere becomes the major poststroke hub for bimanual control. Objective: We tested the following hypotheses: (I) In patients with chronic hemiparetic stroke training on a robotic device, anodal tDCS applied over the primary motor cortex of the undamaged hemisphere enhances bimanual motor skill learning compared to sham tDCS. (II) The severity of impairment correlates with the effect of tDCS on bimanual motor skill learning. (III) Bimanual motor skill learning is less efficient in patients than in healthy individuals (HI). Methods: A total of 17 patients with chronic hemiparetic stroke and 7 healthy individuals learned a complex bimanual cooperation skill on the REAplan® neurorehabilitation robot. The bimanual speed/accuracy trade-off (biSAT), bimanual coordination (biCo), and bimanual force (biFOP) scores were computed for each performance. In patients, real/sham tDCS was applied in a crossover, randomized, double-blind approach. Results: Compared to sham, real tDCS did not enhance bimanual motor skill learning, retention, or generalization in patients, and no correlation with impairment was noted. The healthy individuals performed better than patients on bimanual motor skill learning, but generalization was similar in both groups. Conclusion: A short motor skill learning session with a robotic device resulted in the retention and generalization of a complex skill involving bimanual cooperation. The tDCS strategy that would best enhance bimanual motor skill learning after stroke remains unknown. Clinical trial registration: https://clinicaltrials.gov/ct2/show/NCT02308852, identifier: NCT02308852.
Article
Full-text available
Existing clinical scores of upper limb function often use observer-based ordinal scales that are subjective and commonly have floor and ceiling effects. The purpose of the present study was to develop an upper limb motor task to assess objectively the ability of participants to select and engage motor actions with both hands. A bilateral robotic system was used to quantify upper limb sensorimotor function of participants with stroke. Participants performed an object hit task that required them to hit virtual balls moving towards them in the workspace with virtual paddles attached to each hand. Task difficulty was initially low, but increased with time by increasing the speed and number of balls in the workspace. Data were collected from 262 control participants and 154 participants with recent stroke. Control participants hit ~60 to 90% of the 300 balls with relatively symmetric performance for the two arms. Participants with recent stroke performed the task with most participants hitting fewer balls than 95% of healthy controls (67% of right-affected and 87% of left-affected strokes). Additionally, nearly all participants (97%) identified with visuospatial neglect hit fewer balls than healthy controls. More detailed analyses demonstrated that most participants with stroke displayed asymmetric performance between their affected and non-affected limbs with regards to number of balls hit, workspace area covered by the limb and hand speed. Inter-rater reliability of task parameters was high with half of the correlations above 0.90. Significant correlations were observed between many of the task parameters and the Functional Independence Measure and/or the Behavioural Inattention Test. As this object hit task requires just over two minutes to complete, it provides an objective and easy approach to quantify upper limb motor function and visuospatial skills following stroke.
Article
Full-text available
Combining tDCS with robotic therapy is a new and promising form of neurorehabilitation after stroke, however the effectiveness of this approach is likely to be influenced by the relative timing of the brain stimulation and the therapy. To measure the kinematic and neurophysiological effects of delivering tDCS before, during and after a single session of robotic motor practice (wrist extension). We used a within-subjects repeated-measurement design in 12 chronic (>6 months) stroke survivors. Twenty minutes of anodal tDCS was delivered to the affected hemisphere before, during, or after a 20-minute session of robotic practice. Sham tDCS was also applied during motor practice. Robotic motor performance and corticomotor excitability, assessed through transcranial magnetic stimulation (TMS), were evaluated pre- and post-intervention. Movement speed was increased after motor training (sham tDCS) by ∼20%. Movement smoothness was improved when tDCS was delivered before motor practice (∼15%). TDCS delivered during practice did not offer any benefit, whereas it reduced speed when delivered after practice (∼10%). MEPs were present in ∼50% of patients at baseline; in these subjects motor practice increased corticomotor excitability to the trained muscle. In a cohort of stroke survivors, motor performance kinematics improved when tDCS was delivered prior to robotic training, but not when delivered during or after training. The temporal relationship between non-invasive brain stimulation and neurorehabilitation is important in determining the efficacy and outcome of this combined therapy.
Article
Full-text available
Transcranial direct current stimulation (tDCS) is a non-invasive technique that modulates the excitability of neurons within the primary motor cortex (M1). Research shows that anodal-tDCS applied over the non-dominant M1 (i.e. unilateral stimulation) improves motor function of the non-dominant hand. Similarly, previous studies also show that applying cathodal tDCS over the dominant M1 improves motor function of the non-dominant hand, presumably by reducing interhemispheric inhibition. In the present study, one condition involved anodal-tDCS over the non-dominantM1 (unilateral stimulation) whilst a second condition involved applying cathodal-tDCS over the dominant M1 and anodal-tDCS over non-dominant M1 (bilateral stimulation) to determine if unilateral or bilateral stimulation differentially modulates motor function of the non-dominant hand. Using a randomized, cross-over design,11 right-handed participants underwent three stimulation conditions: 1) unilateral stimulation, that involved anodal-tDCS applied over the non-dominant M1, 2) bilateral stimulation, whereby anodal-tDCS was applied over the non-dominant M1, and cathodal-tDCS over the dominant M1, and 3) sham stimulation. Transcranial magnetic stimulation (TMS) was performed before, immediately after, 30 and 60 minutes after stimulation to elucidate the neural mechanisms underlying any potential after-effects on motor performance. Motor function was evaluated by the Purdue pegboard test. There were significant improvements in motor function following unilateral and bilateral stimulation when compared to sham stimulation at all-time points (all P < 0.05); however there was no difference across time points between unilateral and bilateral stimulation. There was also a similar significant increase in corticomotor excitability with both unilateral and bilateral stimulation immediately post, 30 minutes and 60 minutes compared to sham stimulation (all P < 0.05). Unilateral and bilateral stimulation reduced short-interval intracortical inhibition (SICI) immediately post and at 30 minutes (all P < 0.05), but returned to baseline in both conditions at 60 minutes. There was no difference between unilateral and bilateral stimulation for SICI (P > 0.05). Furthermore, changes in corticomotor plasticity were not related to changes in motor performance. These results indicate that tDCS induced behavioural changes in the non-dominant hand as a consequence of mechanisms associated with use-dependant cortical plasticity that is independent of the electrode arrangement.
Article
Full-text available
Transcranial direct current stimulation (TDCS) of primary motor cortex (M1) can transiently improve paretic hand function in chronic stroke. However, responses are variable so there is incentive to try to improve efficacy and or to predict response in individual patients. Both excitatory (Anodal) stimulation of ipsilesional M1 and inhibitory (Cathodal) stimulation of contralesional M1 can speed simple reaction time. Here we tested whether combining these two effects simultaneously, by using a bilateral M1-M1 electrode montage, would improve efficacy. We tested the physiological efficacy of Bilateral, Anodal or Cathodal TDCS in changing motor evoked potentials (MEPs) in the healthy brain and their behavioural efficacy in changing reaction times with the paretic hand in chronic stroke. In addition, we aimed to identify clinical or neurochemical predictors of patients' behavioural response to TDCS. There were three main findings: 1) Unlike Anodal and Cathodal TDCS, Bilateral M1-M1 TDCS (1mA, 20 minutes) had no significant effect on MEPs in the healthy brain or on reaction time with the paretic hand in chronic stroke patients; 2) GABA levels in ipsilesional M1 predicted patients' behavioural gains from Anodal TDCS; 3) Although patients were in the chronic phase, time since stroke (and its combination with Fugl-Meyer score) was a positive predictor of behavioural gain from Cathodal TDCS. These findings indicate the superiority of Anodal or Cathodal over Bilateral TDCS in changing motor cortico-spinal excitability in the healthy brain and in speeding reaction time in chronic stroke. The identified clinical and neurochemical markers of behavioural response should help to inform the optimization of TDCS delivery and to predict patient outcome variability in future TDCS intervention studies in chronic motor stroke.
Article
Full-text available
Objective: We compared the long-term effect of anodal versus cathodal transcranial direct current stimulation (tDCS) on motor recovery in patients after subacute stroke. Methods: Forty patients with ischemic stroke undergoing rehabilitation were randomly assigned to 1 of 3 groups: Anodal, Cathodal (over-affected and unaffected hemisphere, respectively), and Sham. Each group received tDCS at an intensity of 2 mA for 25 minutes daily for 6 consecutive days over of the motor cortex hand area. Patients were assessed with the National Institutes of Health Stroke Scale (NIHSS), Orgogozo's MCA scale (OMCASS), the Barthel index (BI), and the Medical Research Council (MRC) muscle strength scale at baseline, after the sixth tDCS session and then 1, 2, and 3 months later. Motor cortical excitability was measured with transcranial magnetic stimulation (TMS) at baseline and after the sixth session. Results: By the 3-month follow-up, all groups had improved on all scales with P values ranging from .01 to .0001. Improvement was equal in the Anodal and Cathodal groups. When these treated groups were combined and compared with Sham, significant interactions were seen for the OMCASS and BI scales of functional ability (P = .002 for each). There was increased cortical excitability of the affected hemisphere in all groups with the changes being greater in the real versus sham groups. There were borderline significant improvements in muscle strength. Conclusion: A brief course of 2 types of tDCS stimulation is superior to sham stimulation in enhancing the effect of rehabilitation training to improve motor recovery after stroke.
Article
Full-text available
Background: After stroke, deregulated interhemispheric interactions influence residual paretic hand function. Anodal or cathodal transcranial direct current stimulation (tDCS) can rebalance these abnormal interhemispheric interactions and improve motor function. Objective: We explored whether dual-hemisphere tDCS (dual-tDCS) in participants with chronic stroke can improve fine hand motor function in 2 important aspects: precision grip and dexterity. Methods: In all, 19 chronic hemiparetic individuals with mild to moderate impairment participated in a double-blind, randomized trial. During 2 separate cross-over sessions (real/sham), they performed 10 precision grip movements with a manipulandum and the Purdue Pegboard Test (PPT) before, during, immediately after, and 20 minutes after dual-tDCS applied simultaneously over the ipsilesional (anodal) and contralateral (cathodal) primary motor cortices. Results: The precision grip performed with the paretic hand improved significantly 20 minutes after dual-tDCS, with reduction of the grip force/load force ratio by 7% and in the preloading phase duration by 18% when compared with sham. The dexterity of the paretic hand started improving during dual-tDCS and culminated 20 minutes after the end of dual-tDCS (PPT score +38% vs +5% after sham). The maximal improvements in precision grip and dexterity were observed 20 minutes after dual-tDCS. These improvements correlated negatively with residual hand function quantified with ABILHAND. Conclusions: One bout of dual-tDCS improved the motor control of precision grip and digital dexterity beyond the time of stimulation. These results suggest that dual-tDCS should be tested in longer protocols for neurorehabilitation and with moderate to severely impaired patients. The precise timing of stimulation after stroke onset and associated training should be defined.
Article
Full-text available
BACKGROUND: . After stroke, deregulated interhemispheric interactions influence residual paretic hand function. Anodal or cathodal transcranial direct current stimulation (tDCS) can rebalance these abnormal interhemispheric interactions and improve motor function. OBJECTIVE: . We explored whether dual-hemisphere tDCS (dual-tDCS) in participants with chronic stroke can improve fine hand motor function in 2 important aspects: precision grip and dexterity. METHODS: . In all, 19 chronic hemiparetic individuals with mild to moderate impairment participated in a double-blind, randomized trial. During 2 separate cross-over sessions (real/sham), they performed 10 precision grip movements with a manipulandum and the Purdue Pegboard Test (PPT) before, during, immediately after, and 20 minutes after dual-tDCS applied simultaneously over the ipsilesional (anodal) and contralateral (cathodal) primary motor cortices. RESULTS: . The precision grip performed with the paretic hand improved significantly 20 minutes after dual-tDCS, with reduction of the grip force/load force ratio by 7% and in the preloading phase duration by 18% when compared with sham. The dexterity of the paretic hand started improving during dual-tDCS and culminated 20 minutes after the end of dual-tDCS (PPT score +38% vs +5% after sham). The maximal improvements in precision grip and dexterity were observed 20 minutes after dual-tDCS. These improvements correlated negatively with residual hand function quantified with ABILHAND. CONCLUSIONS: . One bout of dual-tDCS improved the motor control of precision grip and digital dexterity beyond the time of stimulation. These results suggest that dual-tDCS should be tested in longer protocols for neurorehabilitation and with moderate to severely impaired patients. The precise timing of stimulation after stroke onset and associated training should be defined.
Article
Anodal and cathodal transcranial direct current stimulations (tDCS) are both established techniques to induce cortical excitability changes. Typically, in the human motor system, such cortical modulations are inferred through changes in the amplitude of the motor evoked potentials (MEPs). However, it is now possible to directly evaluate tDCS-induced changes at the cortical level by recording the transcranial magnetic stimulation evoked potentials (TEPs) using electroencephalography (EEG). The present study investigated the modulation induced by the tDCS on the motor system. The study evaluates changes in the MEPs, in the amplitude and distribution of the TEPs, in resting state oscillatory brain activity and in behavioural performance in a simple manual response task. Both the short- and long-term tDCS effects were investigated by evaluating their time course at ~0 and 30 minutes after tDCS. Anodal tDCS over the left primary motor cortex (M1) induced an enhancement of corticospinal excitability, whereas cathodal stimulation produced a reduction. These changes in excitability were indexed by changes in MEP amplitude. More interestingly, tDCS modulated the cortical reactivity, which is the neuronal activity evoked by TMS, in a polarity-dependent and site-specific manner. Cortical reactivity increased after anodal stimulation over the left M1, whereas it decreased with cathodal stimulation. These effects were partially present also at long term evaluation. No polarity-specific effect was found either on behavioral measures or on oscillatory brain activity. The latter showed a general increase in the power density of low frequency oscillations (theta and alpha) at both stimulation polarities. Our results suggest that tDCS is able to modulate motor cortical reactivity in a polarity-specific manner, inducing a complex pattern of direct and indirect cortical activation or inhibition of the motor system-related network, which might be related to changes in synaptic efficacy of the motor cortex.