Posts Tagged Transcranial Direct Current Stimulation

[Abstract] Sham tDCS: A hidden source of variability? Reflections for further blinded, controlled trials

Abstract

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique increasingly used to modulate neural activity in the living brain. In order to establish the neurophysiological, cognitive or clinical effects of tDCS,tDCS most studies compare the effects of active tDCS to those observed with a sham tDCS intervention. In most cases, sham tDCS consists in delivering an active stimulation for a few seconds to mimic the sensations observed with active tDCS and keep participants blind to the intervention. However, to date, sham-controlled tDCS studies yield inconsistent results, which might arise in part from sham inconsistencies. Indeed, a multiplicity of sham stimulation protocols is being used in the tDCS research field and might have different biological effects beyond the intended transient sensations. Here, we seek to enlighten the scientific community to this possible confounding factor in order to increase reproducibility of neurophysiological, cognitive and clinical tDCS studies.

via Sham tDCS: A hidden source of variability? Reflections for further blinded, controlled trials – Brain Stimulation: Basic, Translational, and Clinical Research in Neuromodulation

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[ARTICLE] Home-based transcranial direct current stimulation plus tracking training therapy in people with stroke: an open-label feasibility study – Full Text

Abstract

Background

Transcranial direct current stimulation (tDCS) is an effective neuromodulation adjunct to repetitive motor training in promoting motor recovery post-stroke. Finger tracking training is motor training whereby people with stroke use the impaired index finger to trace waveform-shaped lines on a monitor. Our aims were to assess the feasibility and safety of a telerehabilitation program consisting of tDCS and finger tracking training through questionnaires on ease of use, adverse symptoms, and quantitative assessments of motor function and cognition. We believe this telerehabilitation program will be safe and feasible, and may reduce patient and clinic costs.

Methods

Six participants with hemiplegia post-stroke [mean (SD) age was 61 (10) years; 3 women; mean (SD) time post-stroke was 5.5 (6.5) years] received five 20-min tDCS sessions and finger tracking training provided through telecommunication. Safety measurements included the Digit Span Forward Test for memory, a survey of symptoms, and the Box and Block test for motor function. We assessed feasibility by adherence to treatment and by a questionnaire on ease of equipment use. We reported descriptive statistics on all outcome measures.

Results

Participants completed all treatment sessions with no adverse events. Also, 83.33% of participants found the set-up easy, and all were comfortable with the devices. There was 100% adherence to the sessions and all recommended telerehabilitation.

Conclusions

tDCS with finger tracking training delivered through telerehabilitation was safe, feasible, and has the potential to be a cost-effective home-based therapy for post-stroke motor rehabilitation.

Background

Post-stroke motor function deficits stem not only from neurons killed by the stroke, but also from down-regulated excitability in surviving neurons remote from the infarct [1]. This down-regulation results from deafferentation [2], exaggerated interhemispheric inhibition [3], and learned non-use [4]. Current evidence suggests that post-stroke motor rehabilitation therapies should encourage upregulating neurons and should target neuroplasticity through intensive repetitive motor practice [56]. Previously, our group has examined the feasibility and efficacy of a custom finger tracking training program as a way of providing people with stroke with an engaging repetitive motor practice [789]. In this program, the impaired index finger is attached to an electro-goniometer, and participants repeatedly move the finger up and down to follow a target line that is drawn on the display screen. In successive runs, the shape, frequency and amplitude of target line is varied, which forces the participant to focus on the tracking task. In one study, we demonstrated a 23% improvement in hand function (as measured by the Box and Block test; minimal detectable change is 18% [10]) after participants with stroke completed the tracking training program [9]. While our study did not evaluate changes in activity in daily life (ADL) or quality of life (because efficacy of the treatment was not the study objective), the Box and Block test is moderately correlated (r = 0.52) to activities in daily life and quality of life (r = 0.59) [11]. In addition, using fMRI, we showed that training resulted in an activation transition from ipsilateral to contralateral cortical activation in the supplementary motor area, primary motor and sensory areas, and the premotor cortex [9].

Recently, others have shown that anodal transcranial direct current stimulation (tDCS) can boost the beneficial effects of motor rehabilitation, with the boost lasting for at least 3 months post-training [12]. Also, bihemispheric tDCS stimulation (anodal stimulation to excite the ipsilateral side and cathodal stimulation to downregulate the contralateral side) in combination with physical or occupational therapy has been shown to provide a significant improvement in motor function (as measured by Fugl-Meyer and Wolf Motor Function) compared to a sham group [13]. Further, a recent meta-analysis of randomized-controlled trials comparing different forms of tDCS shows that cathodal tDCS is a promising treatment option to improve ADL capacity in people with stroke [14]. Compared to transcutaneous magnetic stimulation (TMS), tDCS devices are inexpensive and easier to operate. Improvement in upper limb motor function can appear after only five tDCS sessions [15], and there are no reports of serious adverse events when tDCS has been used in human trials for periods of less than 40 min at amplitudes of less than 4 mA [16].

Moreover, tDCS stimulation task also seems beneficial for other impairments commonly seen in people post-stroke. Stimulation with tDCS applied for 20 sessions of 30 min over a 4-week period has been shown to decrease depression and improve quality of life in people after a stroke [1718]. Four tDCS sessions for 10 min applied over the primary and sensory cortex in eight patients with sensory impairments more than 10 months post-stroke enhanced tactile discriminative performance [19]. Breathing exercises with tDCS stimulation seems to be more effective than without stimulation in patient with chronic stroke [20], and tDCS has shown promise in treating central post-stroke pain [21]. Finally, preliminary research on the effect of tDCS combined with training on resting-state functional connectivity shows promise to better understand the mechanisms behind inter-subject variability regarding tDCS stimulation [22].

Motor functional outcomes in stroke have declined at discharge from inpatient rehabilitation facilities [2324], likely a result of the pressures to reduce the length of stay at inpatient rehabilitation facilities as part of a changing and increasingly complex health care climate [2526]. Researchers, clinicians, and administrators continue to search for solutions to facilitate and post-stroke rehabilitation after discharge. Specifically, there has been considerable interest in low-cost stroke therapies than can be administered in the home with only a modest level of supervision by clinical professionals.

Home telerehabilitation is a strategy in which rehabilitation in the patient’s home is guided remotely by the therapist using telecommunication technology. If patients can safely apply tDCS to themselves at home, combining telerehabilitation with tDCS would be an easy way to boost therapy without costly therapeutic face-to-face supervision. For people with multiple sclerosis, the study of Charvet et al. (2017) provided tDCS combined with cognitive training, delivered through home telerehabilitation, and demonstrated greater improvement on cognitive measures compared to those who received just the cognitive training [27]. The authors demonstrated the feasibility of remotely supervised, at-home tDCS and established a protocol for safe and reliable delivery of tDCS for clinical studies [28]. Some evidence shows that telerehabilitation approaches are comparable to conventional rehabilitation in improving activities of daily living and motor function for stroke survivors [2930], and that telemedicine for stroke is cost-effective [3132]. A study in 99 people with stroke receiving training using telerehabilitation (either with home exercise program or robot assisted therapy with home program) demonstrated significant improvements in quality of life and depression [33].

A recent search of the literature suggests that to date, no studies combine tDCS with repetitive tracking training in a home telerehabilitation setting to determine whether the combination leads to improved motor rehabilitation in people with stroke. Therefore, the aim of this pilot project was to explore the safety, usability and feasibility of the combined system. For the tDCS treatment, we used a bihemispheric montage with cathodal tDCS stimulation to suppress the unaffected hemisphere in order to promote stroke recovery [34353637]. For the repetitive tracking training therapy, we used a finger tracking task that targets dexterity because 70% of people post-stroke are unable to use their hand with full effectiveness after stroke [38]. Safety was assessed by noting any decline of 2 points or more in the cognitive testing that persists over more than 3 days. We expect day to day variations of 1 digit. Motor decline is defined by a decline of 6 blocks on the Box and Block test due to muscle weakness. This is based on the minimal detectable change (5.5 blocks/min) [10]. The standard error of measurement is at least 2 blocks for the paretic and stronger side. We expect possible variations in muscle tone that could influence the scoring of the test. Usability was assessed through a questionnaire and by observing whether the participant, under remote supervision, could don the apparatus and complete the therapy sessions. Our intent was to set the stage for a future clinical trial to determine the efficacy of this approach.

Methods

Participants

Participants were recruited from a database of people with chronic stroke who had volunteered for previous post-stroke motor therapy research studies at the University of Minnesota. Inclusion criteria were: at least 6 months post-stroke; at least 10 degrees of active flexion and extension motion at the index finger; awareness of tactile sensation on the scalp; and a score of greater than or equal to 24 (normal cognition) on the Mini-Mental State Examination (MMSE) to be cognitively able to understand instructions to don and use the devices [39]. We excluded those who had a seizure within past 2 years, carried implanted medical devices incompatible with tDCS, were pregnant, had non-dental metal in the head or were not able to understand instructions on how to don and use the devices. The study was approved by the University of Minnesota IRB and all enrolled participants consented to be in the study.

Apparatus

tDCS was applied using the StarStim Home Research Kit (NeuroElectrics, Barcelona, Spain). The StarStim system consists of a Neoprene head cap with marked positions for electrode placement, a wireless cap-mounted stimulator and a laptop control computer. Saline-soaked, 5 cm diameter sponge electrodes were used. For electrode placement, we followed a bihemispheric montage [14] involving cathodal stimulation on the unaffected hemisphere with the anode positioned at C3 and the cathode at C4 for participants with left hemisphere stroke, and vice versa for participants with right hemisphere stroke. Stimulation protocols were set by the investigator on a web-based application that communicated with the tDCS control computer. A remote access application (TeamViewer) was also installed on the control computer, as was a video conferencing application (Skype).

The repetitive finger tracking training system was a copy of what we used in our previous stroke studies [789]. The apparatus included an angle sensor mounted to a lightweight brace and aligned with the metacarpophalangeal (MCP) joint of the index finger, a sensor signal conditioning circuit, and a target tracking application loaded on a table computer. Figure 1 shows a participant using the apparatus during a treatment session.

Fig. 1

Fig. 1 Participant with right hemiparesis receiving transcranial direct current magnetic stimulation (tDCS) in their home simultaneous while performing the finger movement tracking task on the tracking computer (left). The tDCS computer (right) shows the supervising investigator, located off-site, who communicated with the participant through the video conferencing application, controlled the tDCS stimulator through web-based software, and controlled the tracking protocols. (Permission was obtained from the participant for the publication of this picture)

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[WEB SITE] Transcranial Direct Current Stimulation – Video

People have investigated brain stimulation since very early times, in ancient Rome torpedo fish were applied to the heads of some patients to relieve headaches, for instance, by their electrical currents. In 1802, Aldini of Italy applied electrical current to the exposed cortex of the human brain and attempted also to treat melancholia with a voltaic pile.

Human brain connected to cables and computer chips. Image Credit: Mopic / Shutterstock

Human brain connected to cables and computer chips. Image Credit: Mopic / ShutterstockEnter a caption

The voltaic pile led to accelerated interest in electrical brain stimulation to treat various disorders, including mental illness. The results were not always encouraging, of course, and it wasn’t until much later, in the middle of the 20th century, that direct current stimulation was used to alter the excitable patterns of the brain. This led to increased interest in using direct current to treat mania or depression. There was a brief upsurge in the use of electroconvulsive therapy to treat schizophrenia and other mental illnesses, but it came to an end in the last decade of the 20th century. Electrical stimulation of the brain became stigmatized and drug therapy took center stage as far as psychiatric treatment was concerned.

Recently, interest has arisen in electrical stimulation of the brain because of the finding that weak transcranial direct current stimulation (tDCS) of the brain produced changes in polarization and excitable thresholds of the neurons, which lasted long beyond the period of stimulation. This has led many to investigate the nature of the changes and the potential applications of this technique to major depressive disorder, schizophrenia, obsessive-compulsive disorder and other disorders of the mind with a basis in brain functioning.

Transcranial Direct Current Stimulation Method

The technique of tDCS depends upon non-invasive stimulation of the brain through the skull, by a small constant current applied through scalp electrodes to the head. This leads to currents flowing through the superficial cortex. The strength of the current is so low that it does not directly cause an action potential in the brain neurons, and so instead regulates the excitability of the brain by making them more or less refractory to other endogenous stimulation according to the polarity of the electrodes. Anodal current is generally stimulatory by inducing increased excitability, but cathodal current reduces it. The effect of a single stimulus lasts for 30-120 minutes.

The way in which the current acts depends upon the polarity and the orientation of the cells. Anodal tDCS produces an inflow of current directed inwardly, which hyperpolarizes the apical dendrites of neurons in the pyramidal cortex, but depolarizes those of the somatic areas. Cathodal tDCS on the other hand leads to the reverse effect. The third factor determining the effect of the current is its dose. The strength of the electrical stimulation may lie between 0.5 and 2 mA, its duration is between 5-40 minutes, and the electrode size ranges from 3-100 cm. By altering these variables, it is possible to regulate the current density and total charge, but it may still be difficult to exactly quantify the total current delivered to the brain because of other factors outside the experimental field, such as scalp and cranial impedance.

The electrodes are placed in accordance with the international Electroencephalogram

System, so that one is on the scalp (the active electrode) and the other on the scalp (bipolar or bicephalic placement) or another part of the body, most commonly the upper arm or the shoulder (termed unipolar or monocephalic placement). The current traces a path from the anode, scalp, cranium, cortex, subcortical region, and cathode, stimulating not only the cortex but deeper structures, both in the deep brain and in the midbrain and spinal cord if unipolar placement is adopted. Secondly, the area stimulated is not confined to that near the electrodes because the current flows into adjoining regions in between and around the electrodes.

Mechanism of tDCS

Electrical stimulation with tDCS seems to produce a two-way modification of post-synaptic neuronal connections which results in the same effects as long-term potentiation or long-term depression of cortical excitability does. This is mediated through NMDA receptors. Glutamate antagonists prevent these long-term effects, while NMDAR agonists increase theiramplitude. Work is still going on as to whether repetitive tDCS could cause a more prolonged alteration of behavior. The stimulation has been found to change motor and emotional functioning, as well as sensory, attention-related, and cognitive responses. It is therefore likely to be useful in several psychiatric disorders. It has been found that glutamate antagonists abolish tDCS after-effects, while NMDA-agonists enhance them.

The Advantages and Disadvantages of tDCS

The technique of tDCS is easy to use, in fact, capable of application at home. It is noninvasive and inexpensive. No serious adverse effects have been noted so far. On the other hand, this very ease of use lends itself to a high potential for misuse, such as recreational use, unsupervised medical use, and unethical use as, for instance, to improve one’s attention span while studying. Its long-term effects are also not well established. Thus while the potential has long been recognized, the implementation of this technique is still not widespread pending proper regulation of its use worldwide.

Further Reading

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[ARTICLE] Transcranial direct current stimulation (tDCS) for upper limb rehabilitation after stroke: future directions. – Full Text

Abstract

Transcranial Direct Current Stimulation (tDCS) is a potentially useful tool to improve upper limb rehabilitation outcomes after stroke, although its effects in this regard have shown to be limited so far. Additional increases in effectiveness of tDCS in upper limb rehabilitation after stroke may for example be achieved by

(1) applying a more focal stimulation approach like high definition tDCS (HD-tDCS),

(2) involving functional imaging techniques during stimulation to identify target areas more exactly,

(3) applying tDCS during Electroencephalography (EEG) (EEG-tDCS),

(4) focusing on an effective upper limb rehabilitation strategy as an effective base treatment after stroke.

Perhaps going even beyond the application of tDCS and applying alternative stimulation techniques such as transcranial Alternating Current Stimulation (tACS) or transcranial Random Noise Stimulation (tRNS) will further increase effectiveness of upper limb rehabilitation after stroke.

Background

Impaired arm function after stroke is both frequent and a considerable burden for people with stroke and their caregivers. An emerging approach for enhancing neural plasticity after acute and chronic brain damage, thus enhancing rehabilitation outcomes in the upper limb rehabilitation after stroke, is non-invasive brain stimulation (NIBS), for example delivered by transcranial direct current stimulation (tDCS) [1]. tDCS is a potentially useful tool for facilitating neural plasticity, because it is relatively inexpensive, easy to administer and safe.

Many small trials regarding the effects of tDCS on arm motor function poststroke were undertaken in the past with partly promising but not conclusive results [23]. Based on these trials a lot of research interest increased in the last 10 to 15 years which still persists. This considerable research interest is a bit surprising first, given the fact that this type of therapy is not used across the board in clinical routine and second, the largest multicenter randomized clinical trial with appropriate methodology including 96 patients did not find clear results in favor of this type of stimulation [4]. A recent network meta-analysis of randomised controlled trials about the effectiveness of tDCS suggested only limited evidence for effectiveness of tDCS after stroke for arm rehabilitation [3]. The optimal stimulation paradigm regarding polarisation, electrode location, amount of direct current applied and stimulation duration still has to be established in order to maximize clinical effectiveness of tDCS [5]. Additionally, doubts emerged that the underlying rationale, the interhemispheric competition model, may be oversimplified or even incorrect [6]. The interhemispheric competition model postulates that a stroke leads to an inhibition of the ipsilateral and to an (over-) excitation of the contralateral brain hemisphere. Hence its clinical implications are to inhibit the contralateral hemisphere and to excited ipsilateral hemisphere. Moreover, electrode positioning and the resulting direction of electric fields as well as variation in head anatomy also modulate stimulation effects [78]. Hence, further approaches may be warranted beyond the approach of neuronavigation prior to stimulation: Additional increases in effectiveness of tDCS in upper limb rehabilitation after stroke may for example be achieved by (1) applying a more focal stimulation approach like high definition tDCS (HD-tDCS), (2) involving functional imaging techniques during stimulation to identify target areas more exactly, (3) applying tDCS during EEG (EEG-tDCS), (4) focusing on an effective upper limb rehabilitation strategy as an effective base treatment after stroke. Perhaps going even beyond the application of tDCS and applying alternative stimulation techniques such as transcranial Alternating Current Stimulation (tACS) [9] or transcranial Random Noise Stimulation (tRNS) [10] will further increase effectiveness of upper limb rehabilitation after stroke.[…]

 

Continue —>  Transcranial direct current stimulation (tDCS) for upper limb rehabilitation after stroke: future directions. | Journal of NeuroEngineering and Rehabilitation | Full Text

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[ARTICLE] Noninvasive Brain Stimulation to Enhance Functional Recovery After Stroke: Studies in Animal Models – Full Text

Background. Stroke is the leading cause of adult disability, but treatment options remain limited, leaving most patients with incomplete recovery. Patient and animal studies have shown potential of noninvasive brain stimulation (NIBS) strategies to improve function after stroke. However, mechanisms underlying therapeutic effects of NIBS are unclear and there is no consensus on which NIBS protocols are most effective.

Objective. Provide a review of articles that assessed effects and mechanisms of repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) in animal stroke models.

Methods. Articles were searched in PubMed, including cross-references.

Results. Nineteen eligible studies reporting effects of rTMS or tDCS after stroke in small rodents were identified. Seventeen of those described improved functional recovery or neuroprotection compared with untreated control or sham-stimulated groups. The effects of rTMS could be related to molecular mechanisms associated with ischemic tolerance, neuroprotection, anti-apoptosis, neurogenesis, angiogenesis, or neuroplasticity. Favorable outcome appeared most effectively when using high-frequency (>5 Hz) rTMS or intermittent theta burst stimulation of the ipsilesional hemisphere. tDCS effects were strongly dependent on stimulation polarity and onset time. Although these findings are promising, most studies did not meet Good Laboratory Practice assessment criteria.

Conclusions. Despite limited data availability, animal stroke model studies demonstrate potential of NIBS to promote stroke recovery through different working mechanisms. Future studies in animal stroke models should adhere to Good Laboratory Practice guidelines and aim to further develop clinically applicable treatment protocols by identifying most favorable stimulation parameters, treatment onset, adjuvant therapies, and underlying modes of action.

Globally, stroke is a devastating neurological disorder and a leading cause of death and acquired disability.1 The majority of stroke patients experience motor impairment, which affects movement of the face, leg, and/or arm on one side of the body.2 Upper limb motor deficiencies are often persistent and disabling, affecting independent functional activities of daily living.3 Unfortunately, most stroke patients recover incompletely after stroke, despite intensive rehabilitation strategies.3,4 Although there is a diverse range of interventions (for overview, see review by Pollock and colleagues4) aimed at improving motor outcome after stoke, there is still a pressing need for novel treatment therapies and continued research to reduce disability and improve functional recovery after stroke.

Noninvasive brain stimulation (NIBS) techniques, such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), have shown promising therapeutic potential in stroke patient studies.5,6 The rationale behind rTMS or tDCS therapy is to modulate cortical excitability, increase neural plasticity, and improve functional motor outcome. For many studies, this approach has been based on the interhemispheric competition model.7 The interhemispheric competition model suggests that functional recovery in stroke patients is hindered due to reduced output from the affected hemisphere and excessive transcallosal inhibition from the unaffected hemisphere.8 Therefore, improvement in motor deficits may be obtained with NIBS strategies that facilitate excitability in the affected hemisphere or suppress inhibitory activity from the unaffected hemisphere.9,10 Depending on the type and duration of the stimulation protocol, both rTMS and tDCS can be used to increase (>5 Hz rTMS; intermittent theta burst stimulation; anodal tDCS) or decrease (⩽1 Hz rTMS; continuous theta burst stimulation; cathodal tDCS) cortical excitability, with potentially lasting effects beyond the stimulation period, promoting mechanisms of synaptic plasticity.11 Evidence suggests that rTMS and tDCS techniques are able to induce changes in cortical excitability associated with facilitation or long-term potentiation like plasticity via glutamatergic neurotransmission, or inhibition and long-term depression via GABAergic neurotransmission.12,13 Furthermore, effects of rTMS and tDCS are not restricted to the target region of stimulation, but also affect distantly connected cortical areas, allowing for the modulation of large-scale neural networks.14

However, despite accumulating evidence of the potential of NIBS, the precise therapeutic mechanisms of action of rTMS and tDCS are largely unidentified and there is no consensus about standardized treatment protocols. Moreover, when deciding on treatment after stroke with either rTMS or tDCS, the poststroke time and lesion status should be considered, and stimulation intensity and duration must be fine-tuned to prevent further tissue damage or the interruption of beneficial plastic changes.15,16 These uncertainties emphasize the critical need for basic understanding of the (patho)physiological processes that are influenced by rTMS and tDCS paradigms after stroke, which may ideally be explored in well-controllable and reproducible experimental animal models.

In animal models of stroke, similar to the human condition, there is a variable degree of spontaneous functional improvement after stroke, associated with a complex cascade of cellular and molecular processes that are activated within minutes after the insult, both in perilesional tissue and remote brain regions.17,18 These events include changes in genetic transcriptional and translational processes, alterations in neurotransmitter interactions, altered secretion of growth factors, gliosis, vascular remodeling, and structural changes in axons, dendrites, and synapses.19,20 Therefore, assessment of the effects of NIBS on endogenous recovery processes in animal stroke models offer excellent opportunities for the exploration of neuroplastic and neuromodulatory mechanisms, which could aid in the optimization of treatment protocols for clinical applications.

Our goal was to provide an overview of studies that assessed functional outcomes and potential mechanisms of action of rTMS and tDCS in animal models of stroke, which may guide future studies that aim to improve mechanistic insights and therapeutic utilization of NIBS effects after stroke.[…]

 

Continue —->  Noninvasive Brain Stimulation to Enhance Functional Recovery After Stroke: Studies in Animal Models – Julia Boonzaier, Geralda A. F. van Tilborg, Sebastiaan F. W. Neggers, Rick M. Dijkhuizen, 2018

 

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[Abstract + References] Transcranial Direct Current Stimulation for Poststroke Motor Recovery: Challenges and Opportunities – PM&R

Abstract

There has been a renewed research interest in transcranial direct current stimulation (tDCS) as an adjunctive tool for poststroke motor recovery as it has a neuro-modulatory effect on the human cortex. However, there are barriers towards its successful application in motor recovery as several scientific issues remain unresolved, including device-related issues (ie, dose-response relationship, safety and tolerability concerns, interhemispheric imbalance model, and choice of montage) and clinical trial-related issues (ie, patient selection, timing of study, and choice of outcomes). This narrative review examines and discusses the existing challenges in using tDCS as a brain modulation tool in facilitating recovery after stroke. Potential solutions pertinent to using tDCS with the goal of harnessing the brains plasticity are proposed.

References

  1. Kreisel, S.H., Bazner, H., Hennerici, M.G. Pathophysiology of stroke rehabilitation: Temporal aspects of neuro-functional recovery. Cerebrovasc Dis2006;21:6–17.
  2. Nitsche, M.A., Paulus, W. Sustained excitability elevations induced by transcranial DC motor cortex stimulation in humans. Neurology2001;57:1899–1901.
  3. Fritsch, B., Reis, J., Martinowich, K. et al, Direct current stimulation promotes BDNF-dependent synaptic plasticity: Potential implications for motor learning. Neuron2010;66:198–204.
  4. Schlaug, G., Renga, V., Nair, D. Transcranial direct current stimulation in stroke recovery. Arch Neurol2008;65:1571–1576.
  5. Brunoni, A.R., Nitsche, M.A., Bolognini, N. et al, Clinical research with transcranial direct current stimulation (TDCS): Challenges and future directions. Brain Stimul2012;5:175–195.
  6. Fregni, F., Nitsche, M., Loo, C. et al, Regulatory considerations for the clinical and research use of transcranial direct current stimulation (TDCS): Review and recommendations from an expert panel.Clin Res Regul Aff2015;32:22–35.
  7. Feng, W.W., Bowden, M.G., Kautz, S. Review of transcranial direct current stimulation in poststroke recovery. Top Stroke Rehabil2013;20:68–77.
  8. Ferbert, A., Priori, A., Rothwell, J.C., Day, B.L., Colebatch, J.G., Marsden, C.D. Interhemispheric inhibition of the human motor cortex. J Physiol1992;453:525–546.
  9. Di Lazzaro, V., Oliviero, A., Profice, P. et al, Direct demonstration of interhemispheric inhibition of the human motor cortex produced by transcranial magnetic stimulation. Exp Brain Res1999;124:520–524.
  10. Stinear, C.M., Petoe, M.A., Byblow, W.D. Primary motor cortex excitability during recovery after stroke: Implications for neuromodulation. Brain Stimul2015;8:1183–1190.
  11. McDonnell, M.N., Stinear, C.M. TMS measures of motor cortex function after stroke: A meta-analysis. Brain Stimul2017;10:721–734.
  12. Wu, D., Qian, L., Zorowitz, R.D., Zhang, L., Qu, Y., Yuan, Y. Effects on decreasing upper-limb poststroke muscle tone using transcranial direct current stimulation: A randomized sham-controlled study. Arch Phys Med Rehabil2013;94:1–8.
  13. Waters, S., Wiestler, T., Diedrichsen, J. Cooperation not competition: Bihemispheric tdcs and fmri show role for ipsilateral hemisphere in motor learning. J Neurosci2017;37:7500–7512.
  14. Truong, D.Q., Huber, M., Xie, X. et al, Clinician accessible tools for gui computational models of transcranial electrical stimulation: Bonsai and spheres. Brain Stimul2014;7:521–524.
  15. Saturnino, G.B., Antunes, A., Thielscher, A. On the importance of electrode parameters for shaping electric field patterns generated by TDCS. NeuroImage2015;120:25–35.
  16. Vines, B.W., Cerruti, C., Schlaug, G. Dual-hemisphere TDCS facilitates greater improvements for healthy subjects’ non-dominant hand compared to uni-hemisphere stimulation. BMC Neurosci2008;9:103.
  17. Chi, R.P., Fregni, F., Snyder, A.W. Visual memory improved by non-invasive brain stimulation. Brain Res2010;1353:168–175.
  18. Chhatbar, P.Y., Ramakrishnan, V., Kautz, S., George, M.S., Adams, R.J., Feng, W. Transcranial direct current stimulation post-stroke upper extremity motor recovery studies exhibit a dose-response relationship. Brain Stimul2016;9:16–26.
  19. Nitsche, M.A., Paulus, W. Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation. J Physiol2000;527:633–639.
  20. Bastani, A., Jaberzadeh, S. Differential modulation of corticospinal excitability by different current densities of anodal transcranial direct current stimulation. PLoS One2013;8:e72254.
  21. Bastani, A., Jaberzadeh, S. A-TDCS differential modulation of corticospinal excitability: The effects of electrode size. Brain Stimul2013;6:932–937.
  22. Liebetanz, D., Koch, R., Mayenfels, S., Konig, F., Paulus, W., Nitsche, M.A. Safety limits of cathodal transcranial direct current stimulation in rats. Clin Neurophysiol2009;120:1161–1167.
  23. Chhatbar, P.Y., George, M.S., Kautz, S.A., Feng, W. Quantitative reassessment of safety limits of tdcs for two animal studies. Brain Stimul2017;10:1011–1012.
  24. Chhatbar, P.Y., George, M.S., Kautz, S.A., Feng, W. Charge density, not current density, is a more comprehensive safety measure of transcranial direct current stimulation. Brain Behav Immun2017;66:414–415.
  25. Palm, U., Keeser, D., Schiller, C. et al, Skin lesions after treatment with transcranial direct current stimulation (TDCS). Brain Stimul2008;1:386–387.
  26. Frank, E., Wilfurth, S., Landgrebe, M., Eichhammer, P., Hajak, G., Langguth, B. Anodal skin lesions after treatment with transcranial direct current stimulation. Brain Stimul2010;3:58–59.
  27. Wang, J., Wei, Y., Wen, J., Li, X. Skin burn after single session of transcranial direct current stimulation (TDCS). Brain Stimul2015;8:165–166.
  28. Minhas, P., Datta, A., Bikson, M. Cutaneous perception during TDCS: Role of electrode shape and sponge salinity. Clin Neurophysiol2011;122:637–638.
  29. Chhatbar, P.Y., Chen, R., Deardorff, R. et al, Safety and tolerability of transcranial direct current stimulation to stroke patients—a phase I current escalation study. Brain Stimul2017;10:553–559.
  30. Kessler, S.K., Minhas, P., Woods, A.J., Rosen, A., Gorman, C., Bikson, M. Dosage considerations for transcranial direct current stimulation in children: A computational modeling study. PLoS One2013;8:e76112.
  31. Truong, D.Q., Magerowski, G., Blackburn, G.L., Bikson, M., Alonso-Alonso, M. Computational modeling of transcranial direct current stimulation (TDCS) in obesity: Impact of head fat and dose guidelines.Neuroimage Clin2013;2:759–766.
  32. Datta, A., Bikson, M., Fregni, F. Transcranial direct current stimulation in patients with skull defects and skull plates: High-resolution computational FEM study of factors altering cortical current flow.Neuroimage2010;52:1268–1278.
  33. Datta, A., Baker, J.M., Bikson, M., Fridriksson, J. Individualized model predicts brain current flow during transcranial direct-current stimulation treatment in responsive stroke patient. Brain Stimul2011;4:169–174.
  34. Suh, H.S., Lee, W.H., Kim, T.-S. Influence of anisotropic conductivity in the skull and white matter on transcranial direct current stimulation via an anatomically realistic finite element head model. Phys Med Biol2012;57:6961.
  35. Lee, W., Seo, H., Kim, S., Cho, M., Lee, S., Kim, T.-S. Influence of white matter anisotropy on the effects of transcranial direct current stimulation: A finite element study. in: C.K. Lim, J.C.H. Goh (Eds.)ICBME 2008-13th International Conference on Biomedical EngineeringSpringerHeidelberg2009:460–464.
  36. Metwally, M.K., Han, S.M., Kim, T.S. The effect of tissue anisotropy on the radial and tangential components of the electric field in transcranial direct current stimulation. Med Biol Eng Comput2015;53:1085–1101.
  37. Huang, Y., Liu, A.A., Lafon, B. et al, Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation. Elife2017;6:e18834.
  38. Opitz, A., Falchier, A., Yan, C.G. et al, Spatiotemporal structure of intracranial electric fields induced by transcranial electric stimulation in humans and nonhuman primates. Sci Rep2016;6:31236.
  39. Chhatbar, P.Y., Kautz, S.A., Takacs, I. et al, Evidence of transcranial direct current stimulation-generated electric fields at subthalamic level in human brain in vivo. Brain Stimul2018;11:727–733.
  40. Lindenberg, R., Renga, V., Zhu, L.L., Nair, D., Schlaug, G. Bihemispheric brain stimulation facilitates motor recovery in chronic stroke patients. Neurology2010;75:2176–2184.
  41. Levy, R.M., Harvey, R.L., Kissela, B.M. et al, Epidural electrical stimulation for stroke rehabilitation: Results of the prospective, multicenter, randomized, single-blinded Everest trial. Neurorehabil Neural Repair2016;30:107–119.
  42. Feng, W., Wang, J., Chhatbar, P.Y. et al, Corticospinal tract lesion load—a potential imaging biomarker for stroke motor outcomes. Ann Neurol2015;78:860–870.
  43. Dromerick, A.W., Edwardson, M.A., Edwards, D.F. et al, Critical periods after stroke study: Translating animal stroke recovery experiments into a clinical trial. Front Hum Neurosci2015;9:231.
  44. Jorgensen, H.S., Nakayama, H., Raaschou, H.O., Vive-Larsen, J., Stoier, M., Olsen, T.S. Outcome and time course of recovery in stroke. Part II: Time course of recovery. The Copenhagen Stroke Study.Arch Phys Med Rehabil1995;76:406–412.
  45. Cortes, J.C., Goldsmith, J., Harran, M.D. et al, A short and distinct time window for recovery of arm motor control early after stroke revealed with a global measure of trajectory kinematics. Neurorehabil Neural Repair2017;31:552–560.
  46. Bushnell, C., Bettger, J.P., Cockroft, K.M. et al, Chronic stroke outcome measures for motor function intervention trials: Expert panel recommendations. Circ Cardiovasc Qual Outcomes2015;8:S163–S169.
  47. Viana, R.T., Laurentino, G.E., Souza, R.J. et al, Effects of the addition of transcranial direct current stimulation to virtual reality therapy after stroke: A pilot randomized controlled trial.NeuroRehabilitation2014;34:437–446.
  48. Fusco, A., Assenza, F., Iosa, M. et al, The ineffective role of cathodal tdcs in enhancing the functional motor outcomes in early phase of stroke rehabilitation: An experimental trial. Biomed Res Int2014;2014:547290.
  49. Kim, D.Y., Lim, J.Y., Kang, E.K. et al, Effect of transcranial direct current stimulation on motor recovery in patients with subacute stroke. Am J Phys Med Rehabil2010;89:879–886.
  50. Boggio, P.S., Nunes, A., Rigonatti, S.P., Nitsche, M.A., Pascual-Leone, A., Fregni, F. Repeated sessions of noninvasive brain DC stimulation is associated with motor function improvement in stroke patients. Restor Neurol Neurosci2007;25:123–129.
  51. Bolognini, N., Vallar, G., Casati, C., Latif, L.A., El-Nazer, R., Williams, J. et al, Neurophysiological and behavioral effects of TDCS combined with constraint-induced movement therapy in poststroke patients. Neurorehabil Neural Repair2011;25:819–829.
  52. Hesse, S., Waldner, A., Mehrholz, J., Tomelleri, C., Pohl, M., Werner, C. Combined transcranial direct current stimulation and robot-assisted arm training in subacute stroke patients: An exploratory, randomized multicenter trial. Neurorehabil Neural Repair2011;25:838–846.
  53. Di Lazzaro, V., Dileone, M., Capone, F. et al, Immediate and late modulation of interhemipheric imbalance with bilateral transcranial direct current stimulation in acute stroke. Brain Stimul2014;7:841–848.
  54. Rossi, C., Sallustio, F., Di Legge, S., Stanzione, P., Koch, G. Transcranial direct current stimulation of the affected hemisphere does not accelerate recovery of acute stroke patients. Eur J Neurol2013;20:202–204.
  55. Nair, D.G., Renga, V., Lindenberg, R., Zhu, L., Schlaug, G. Optimizing recovery potential through simultaneous occupational therapy and non-invasive brain-stimulation using tdcs. Restor Neurol Neurosci2011;29:411–420.
  56. Ang, K.K., Guan, C., Phua, K.S. et al, Facilitating effects of transcranial direct current stimulation on motor imagery brain-computer interface with robotic feedback for stroke rehabilitation. Arch Phys Med Rehabil2015;96:S79–S87.
  57. Sattler, V., Acket, B., Raposo, N. et al, Anodal tdcs combined with radial nerve stimulation promotes hand motor recovery in the acute phase after ischemic stroke. Neurorehabil Neural Repair2015;29:743–754.
  58. Andrade, S.M., Batista, L.M., Nogueira, L.L. et al, Constraint-induced movement therapy combined with transcranial direct current stimulation over premotor cortex improves motor function in severe stroke: A pilot randomized controlled trial. Rehabil Res Pract2017;2017:6842549.
  59. Figlewski, K., Blicher, J.U., Mortensen, J., Severinsen, K.E., Nielsen, J.F., Andersen, H. Transcranial direct current stimulation potentiates improvements in functional ability in patients with chronic stroke receiving constraint-induced movement therapy. Stroke2017;48:229–232.
  60. Medeiros, L.F., de Souza, I.C.C., Vidor, L.P. et al, Neurobiological effects of transcranial direct current stimulation: A review. Front Psychiatry2012;3:110.

 

via Transcranial Direct Current Stimulation for Poststroke Motor Recovery: Challenges and Opportunities – PM&R

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[Abstract] Combined transcranial direct current stimulation with virtual reality exposure for posttraumatic stress disorder: Feasibility and pilot results

Abstract

Background

Facilitating neural activity using non-invasive brain stimulation may improve extinction-based treatments for posttraumatic stress disorder (PTSD).

Objective/hypothesis

Here, we examined the feasibility of simultaneous transcranial direct current stimulation (tDCS) application during virtual reality (VR) to reduce psychophysiological arousal and symptoms in Veterans with PTSD.

Methods

Twelve Veterans with PTSD received six combat-related VR exposure sessions during sham-controlled tDCS targeting ventromedial prefrontal cortex. Primary outcome measures were changes in skin conductance-based arousal and self-reported PTSD symptom severity.

Results

tDCS + VR components were combined without technical difficulty. We observed a significant interaction between reduction in arousal across sessions and tDCS group (p = .03), indicating that the decrease in physiological arousal was greater in the tDCS + VR versus sham group. We additionally observed a clinically meaningful reduction in PTSD symptom severity.

Conclusions

This study demonstrates feasibility of applying tDCS during VR. Preliminary data suggest a reduction in psychophysiological arousal and PTSD symptomatology, supporting future studies.

via Combined transcranial direct current stimulation with virtual reality exposure for posttraumatic stress disorder: Feasibility and pilot results – Brain Stimulation: Basic, Translational, and Clinical Research in Neuromodulation

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[ARTICLE] Home-based transcranial direct current stimulation plus tracking training therapy in people with stroke: an open-label feasibility study – Full Text

Abstract

Background

Transcranial direct current stimulation (tDCS) is an effective neuromodulation adjunct to repetitive motor training in promoting motor recovery post-stroke. Finger tracking training is motor training whereby people with stroke use the impaired index finger to trace waveform-shaped lines on a monitor. Our aims were to assess the feasibility and safety of a telerehabilitation program consisting of tDCS and finger tracking training through questionnaires on ease of use, adverse symptoms, and quantitative assessments of motor function and cognition. We believe this telerehabilitation program will be safe and feasible, and may reduce patient and clinic costs.

Methods

Six participants with hemiplegia post-stroke [mean (SD) age was 61 (10) years; 3 women; mean (SD) time post-stroke was 5.5 (6.5) years] received five 20-min tDCS sessions and finger tracking training provided through telecommunication. Safety measurements included the Digit Span Forward Test for memory, a survey of symptoms, and the Box and Block test for motor function. We assessed feasibility by adherence to treatment and by a questionnaire on ease of equipment use. We reported descriptive statistics on all outcome measures.

Results

Participants completed all treatment sessions with no adverse events. Also, 83.33% of participants found the set-up easy, and all were comfortable with the devices. There was 100% adherence to the sessions and all recommended telerehabilitation.

Conclusions

tDCS with finger tracking training delivered through telerehabilitation was safe, feasible, and has the potential to be a cost-effective home-based therapy for post-stroke motor rehabilitation.

Background

Post-stroke motor function deficits stem not only from neurons killed by the stroke, but also from down-regulated excitability in surviving neurons remote from the infarct [1]. This down-regulation results from deafferentation [2], exaggerated interhemispheric inhibition [3], and learned non-use [4]. Current evidence suggests that post-stroke motor rehabilitation therapies should encourage upregulating neurons and should target neuroplasticity through intensive repetitive motor practice [56]. Previously, our group has examined the feasibility and efficacy of a custom finger tracking training program as a way of providing people with stroke with an engaging repetitive motor practice [789]. In this program, the impaired index finger is attached to an electro-goniometer, and participants repeatedly move the finger up and down to follow a target line that is drawn on the display screen. In successive runs, the shape, frequency and amplitude of target line is varied, which forces the participant to focus on the tracking task. In one study, we demonstrated a 23% improvement in hand function (as measured by the Box and Block test; minimal detectable change is 18% [10]) after participants with stroke completed the tracking training program [9]. While our study did not evaluate changes in activity in daily life (ADL) or quality of life (because efficacy of the treatment was not the study objective), the Box and Block test is moderately correlated (r = 0.52) to activities in daily life and quality of life (r = 0.59) [11]. In addition, using fMRI, we showed that training resulted in an activation transition from ipsilateral to contralateral cortical activation in the supplementary motor area, primary motor and sensory areas, and the premotor cortex [9].

Recently, others have shown that anodal transcranial direct current stimulation (tDCS) can boost the beneficial effects of motor rehabilitation, with the boost lasting for at least 3 months post-training [12]. Also, bihemispheric tDCS stimulation (anodal stimulation to excite the ipsilateral side and cathodal stimulation to downregulate the contralateral side) in combination with physical or occupational therapy has been shown to provide a significant improvement in motor function (as measured by Fugl-Meyer and Wolf Motor Function) compared to a sham group [13]. Further, a recent meta-analysis of randomized-controlled trials comparing different forms of tDCS shows that cathodal tDCS is a promising treatment option to improve ADL capacity in people with stroke [14]. Compared to transcutaneous magnetic stimulation (TMS), tDCS devices are inexpensive and easier to operate. Improvement in upper limb motor function can appear after only five tDCS sessions [15], and there are no reports of serious adverse events when tDCS has been used in human trials for periods of less than 40 min at amplitudes of less than 4 mA [16].

Moreover, tDCS stimulation task also seems beneficial for other impairments commonly seen in people post-stroke. Stimulation with tDCS applied for 20 sessions of 30 min over a 4-week period has been shown to decrease depression and improve quality of life in people after a stroke [1718]. Four tDCS sessions for 10 min applied over the primary and sensory cortex in eight patients with sensory impairments more than 10 months post-stroke enhanced tactile discriminative performance [19]. Breathing exercises with tDCS stimulation seems to be more effective than without stimulation in patient with chronic stroke [20], and tDCS has shown promise in treating central post-stroke pain [21]. Finally, preliminary research on the effect of tDCS combined with training on resting-state functional connectivity shows promise to better understand the mechanisms behind inter-subject variability regarding tDCS stimulation [22].

Motor functional outcomes in stroke have declined at discharge from inpatient rehabilitation facilities [2324], likely a result of the pressures to reduce the length of stay at inpatient rehabilitation facilities as part of a changing and increasingly complex health care climate [2526]. Researchers, clinicians, and administrators continue to search for solutions to facilitate and post-stroke rehabilitation after discharge. Specifically, there has been considerable interest in low-cost stroke therapies than can be administered in the home with only a modest level of supervision by clinical professionals.

Home telerehabilitation is a strategy in which rehabilitation in the patient’s home is guided remotely by the therapist using telecommunication technology. If patients can safely apply tDCS to themselves at home, combining telerehabilitation with tDCS would be an easy way to boost therapy without costly therapeutic face-to-face supervision. For people with multiple sclerosis, the study of Charvet et al. (2017) provided tDCS combined with cognitive training, delivered through home telerehabilitation, and demonstrated greater improvement on cognitive measures compared to those who received just the cognitive training [27]. The authors demonstrated the feasibility of remotely supervised, at-home tDCS and established a protocol for safe and reliable delivery of tDCS for clinical studies [28]. Some evidence shows that telerehabilitation approaches are comparable to conventional rehabilitation in improving activities of daily living and motor function for stroke survivors [2930], and that telemedicine for stroke is cost-effective [3132]. A study in 99 people with stroke receiving training using telerehabilitation (either with home exercise program or robot assisted therapy with home program) demonstrated significant improvements in quality of life and depression [33].

A recent search of the literature suggests that to date, no studies combine tDCS with repetitive tracking training in a home telerehabilitation setting to determine whether the combination leads to improved motor rehabilitation in people with stroke. Therefore, the aim of this pilot project was to explore the safety, usability and feasibility of the combined system. For the tDCS treatment, we used a bihemispheric montage with cathodal tDCS stimulation to suppress the unaffected hemisphere in order to promote stroke recovery [34353637]. For the repetitive tracking training therapy, we used a finger tracking task that targets dexterity because 70% of people post-stroke are unable to use their hand with full effectiveness after stroke [38]. Safety was assessed by noting any decline of 2 points or more in the cognitive testing that persists over more than 3 days. We expect day to day variations of 1 digit. Motor decline is defined by a decline of 6 blocks on the Box and Block test due to muscle weakness. This is based on the minimal detectable change (5.5 blocks/min) [10]. The standard error of measurement is at least 2 blocks for the paretic and stronger side. We expect possible variations in muscle tone that could influence the scoring of the test. Usability was assessed through a questionnaire and by observing whether the participant, under remote supervision, could don the apparatus and complete the therapy sessions. Our intent was to set the stage for a future clinical trial to determine the efficacy of this approach.

Methods

Participants

Participants were recruited from a database of people with chronic stroke who had volunteered for previous post-stroke motor therapy research studies at the University of Minnesota. Inclusion criteria were: at least 6 months post-stroke; at least 10 degrees of active flexion and extension motion at the index finger; awareness of tactile sensation on the scalp; and a score of greater than or equal to 24 (normal cognition) on the Mini-Mental State Examination (MMSE) to be cognitively able to understand instructions to don and use the devices [39]. We excluded those who had a seizure within past 2 years, carried implanted medical devices incompatible with tDCS, were pregnant, had non-dental metal in the head or were not able to understand instructions on how to don and use the devices. The study was approved by the University of Minnesota IRB and all enrolled participants consented to be in the study.

Apparatus

tDCS was applied using the StarStim Home Research Kit (NeuroElectrics, Barcelona, Spain). The StarStim system consists of a Neoprene head cap with marked positions for electrode placement, a wireless cap-mounted stimulator and a laptop control computer. Saline-soaked, 5 cm diameter sponge electrodes were used. For electrode placement, we followed a bihemispheric montage [14] involving cathodal stimulation on the unaffected hemisphere with the anode positioned at C3 and the cathode at C4 for participants with left hemisphere stroke, and vice versa for participants with right hemisphere stroke. Stimulation protocols were set by the investigator on a web-based application that communicated with the tDCS control computer. A remote access application (TeamViewer) was also installed on the control computer, as was a video conferencing application (Skype).

The repetitive finger tracking training system was a copy of what we used in our previous stroke studies [789]. The apparatus included an angle sensor mounted to a lightweight brace and aligned with the metacarpophalangeal (MCP) joint of the index finger, a sensor signal conditioning circuit, and a target tracking application loaded on a table computer. Figure 1 shows a participant using the apparatus during a treatment session.

Fig. 1

Fig. 1Participant with right hemiparesis receiving transcranial direct current magnetic stimulation (tDCS) in their home simultaneous while performing the finger movement tracking task on the tracking computer (left). The tDCS computer (right) shows the supervising investigator, located off-site, who communicated with the participant through the video conferencing application, controlled the tDCS stimulator through web-based software, and controlled the tracking protocols. (Permission was obtained from the participant for the publication of this picture)

[…]

 

Continue —>  Home-based transcranial direct current stimulation plus tracking training therapy in people with stroke: an open-label feasibility study | Journal of NeuroEngineering and Rehabilitation | Full Text

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[Abstract] A meta-analysis of the efficacy of anodal transcranial direct current stimulation for upper limb motor recovery in stroke survivors

Abstract

Study Design

Systematic review and meta-analysis.

Introduction

Prior reviews on the effects of anodal transcranial direct current stimulation (a-tDCS) have shown the effectiveness of a-tDCS on corticomotor excitability and motor function in healthy individuals but nonsignificant effect in subjects with stroke.

Purpose

To summarize and evaluate the evidence for the efficacy of a-tDCS in the treatment of upper limb motor impairment after stroke.

Methods

A meta-analysis of randomized controlled trials that compared a-tDCS with placebo and change from baseline.

Results

A pooled analysis showed a significant increase in scores in favor of a-tDCS (standard mean difference [SMD]=0.40, 95% confidence interval [CI]=0.10–0.70, p=0.010, compared with baseline). A similar effect was observed between a-tDCS and sham (SMD=0.49, 95% CI=0.18–0.81, p=0.005).

Conclusion

This meta-analysis of eight randomized placebo-controlled trials provides further evidence that a-tDCS may benefit motor function of the paretic upper limb in patients suffering from chronic stroke.

via A meta-analysis of the efficacy of anodal transcranial direct current stimulation for upper limb motor recovery in stroke survivors – Journal of Hand Therapy

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[Abstract] Impact of transcranial direct current stimulation on structural plasticity of the somatosensory system

Significance Recently, it has been shown that repeated anodal transcranial direct current stimulation (tDCS) applied to the somatosensory system induces functionalchanges at its site of application in the primary somatosensory cortex and therefore at an early stage of information processing (Hilgenstock, Weiss, Huonker, & Witte, ). The present study complements this finding by showing that tDCS also affects the somatosensory system on a structural level, however, at a late stage of decision making, probably at the stage of decision readout. Thus, tDCS seems capable of inducing changes at all levels of the somatosensory processing hierarchy.

Abstract

While there is a growing body of evidence regarding the behavioral and neurofunctional changes in response to the longitudinal delivery of transcranial direct current stimulation (tDCS), there is limited evidence regarding its structural effects. Therefore, the present study was intended to investigate the effect of repeatedly applied anodal tDCS over the primary somatosensory cortex on the gray matter (GM) and white matter (WM) compartment of the brain. Structural tDCS effects were, moreover, related to effects evidenced by functional imaging and behavioral assessment. tDCS was applied over the course of 5 days in 25 subjects with concomitant assessment of tactile acuity of the right and left index finger as well as imaging at baseline, after the last delivery of tDCS and at follow‐up 4 weeks thereafter. Irrespective of the stimulation condition (anodal vs. sham), voxel‐based morphometry revealed a behaviorally relevant decrease of GM in the precuneus co‐localized with a functional change of its activity. Moreover, there was a decrease in GM of the bilateral lingual gyrus and the right cerebellum. Diffusion tensor imaging analysis showed an increase of fractional anisotropy exclusively in the tDCSanodal condition in the left frontal cortex affecting the final stretch of a somatosensory decision making network comprising the middle and superior frontal gyrus as well as regions adjacent to the genu of the corpus callosum. Thus, this is the first study in humans to identify structural plasticity in the GM compartment and tDCS‐specific changes in the WM compartment in response to somatosensory learning.

 

via Impact of transcranial direct current stimulation on structural plasticity of the somatosensory system – Hirtz – 2018 – Journal of Neuroscience Research – Wiley Online Library

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