tDCS application for postural control in Parkinson's disease: Effects are associated with baseline characteristics.

INTRODUCTION: Transcranial direct current stimulation (tDCS) improves postural response to perturbation in patients with Parkinson's disease (PwPD). However, the influence of baseline characteristics such as clinical/cognitive and postural performance on the response to tDCS remains unclear. OBJECTIVE: To investigate whether baseline level of postural control (performance during sham condition) and clinical/cognitive characteristics are associated with tDCS-related changes in postural responses to external perturbations in PwPD. METHODS: Twenty-four PwPD participated in this study. Clinical assessment included disease severity, disease duration, levodopa equivalent dose and global cognition. Anodal tDCS protocols targeting the primary motor cortex were applied in two separate sessions (at least 2 weeks apart): active (2 mA for 20 min) and sham stimulation. Seven trials with the backward translation of the support base (20 cm/s and 5 cm) were performed after tDCS. Postural outcomes included the recovery time to stable position and onset latency of the medial gastrocnemius (MG). Pearson and Spearman correlation tests were performed. RESULTS: No significant correlations were observed between clinical/cognitive characteristics and tDCS-related changes in postural responses. Negative associations were observed between the baseline level of postural control and tDCS-related changes in postural responses for the recovery time (r = -0.657; p < 0.001) and the MG onset latency (rs = -0.539; p = 0.007). PwPD with worse baseline postural control demonstrated greater improvement after active stimulation. CONCLUSIONS: Findings suggest that tDCS-related effects on postural response to perturbation are related to the baseline level of postural control, but not to clinical characteristics in PwPD. Those with worse baseline postural control responded better to tDCS.

Effects of Robotic Therapy Associated With Noninvasive Brain Stimulation on Upper-Limb Rehabilitation After Stroke: Systematic Review and Meta-analysis of Randomized Clinical Trials.

BACKGROUND: Robot-assisted therapy and noninvasive brain stimulation (NIBS) are promising strategies for stroke rehabilitation. OBJECTIVE: This systematic review and meta-analysis aims to evaluate the evidence of NIBS as an add-on intervention to robotic therapy in order to improve outcomes of upper-limb motor impairment or activity in individuals with stroke. METHODS: This study was performed according to the PRISMA Protocol and was previously registered on the PROSPERO Platform (CRD42017054563). Seven databases and gray literature were systematically searched by 2 reviewers, and 1176 registers were accessed. Eight randomized clinical trials with upper-limb body structure/function or activity limitation outcome measures were included. Subgroup analyses were performed according to phase poststroke, device characteristics (ie, arm support, joints involved, unimanual or bimanual training), NIBS paradigm, timing of stimulation, and number of sessions. The Grade-Pro Software was used to assess quality of the evidence. RESULTS: A nonsignificant homogeneous summary effect size was found both for body structure function domain (mean difference [MD] = 0.15; 95% CI = -3.10 to 3.40; P = 0.93; I2 = 0%) and activity limitation domain (standard MD = 0.03; 95% CI = -0.28 to 0.33; P = 0.87; I2 = 0%). CONCLUSIONS: According to this systematic review and meta-analysis, at the moment, there are not enough data about the benefits of NIBS as an add-on intervention to robot-assisted therapy on upper-limb motor function or activity in individuals with stroke.

Noninvasive Brain Stimulation Does Not Improve Neuropathic Pain in Individuals With Spinal Cord Injury: Evidence From a Meta-Analysis of 11 Randomized Controlled Trials.

OBJECTIVE: The aim of the study was to examine the effectiveness of noninvasive brain stimulation on neuropathic pain in individuals with spinal cord injury. METHODS: A meta-analysis on pain intensity, depression, and anxiety levels was conducted to evaluate the effect of noninvasive brain stimulation on neuropathic pain in individuals with spinal cord injury. The authors searched Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (PubMed), Embase (OvidSP), PsycINFO (OvidSP), and Physiotherapy Evidence Database (PEDro). Randomized controlled trials comparing noninvasive brain stimulation with sham stimulation were included. RESULTS: Eleven studies were selected. The pooled analysis demonstrated no significant effect of repetitive transcranial magnetic stimulation, transcranial direct current stimulation, or cranial electrotherapy stimulation on neuropathic pain reduction after spinal cord injury. In addition, noninvasive brain stimulation showed no beneficial effect over sham stimulation on the improvement of depression, while it yielded a significant reduction of anxiety levels immediately after treatment. Subgroup analysis showed that only cranial electrotherapy stimulation had a significant effect on the reduction of anxiety levels among the three types of noninvasive brain stimulation. CONCLUSIONS: In individuals with spinal cord injury, no significant effects of noninvasive brain stimulation on neuropathic pain and depression were observed. Cranial electrotherapy stimulation may be beneficial for the management of anxiety. These findings do not support the routine use of noninvasive brain stimulation for neuropathic pain in individuals with spinal cord injury.

Statistical power estimation in non-invasive brain stimulation studies and its clinical implications: An exploratory study of the meta-analyses.

BACKGROUND: Non-invasive brain stimulation (NIBS) techniques have emerged as a promising tool for understanding and treating psychiatric disorders, necessitating a caution in terms of interpreting research results. OBJECTIVE: This study aimed at systematically evaluating a representative sample of research conducted using NIBS interventions in neuro-psychiatric conditions, and assessing the power these studies achieved, given their sample sizes. METHODS: A database search was conducted with defined keyword combinations. Using reported summary effects of the meta-analyses as estimate of the true effects, we calculated achieved power of each individual study to detect the effect indicated by the corresponding meta-analysis. RESULTS: Findings suggest that mean and median powers in the field of NIBS were 0.50, with a mode at 0.83 (range 0.05-1.00). When analysed separately, the median powers were 0.27 for tDCS, 0.70 for TMS and 0.97 for ECT. These studies had a mean total sample size of 22.2 ±â€¯24.9 subjects and the median reported effect size across all studies was 0.61. CONCLUSION: According to our findings, studies conducted in NIBS miss around 50% of true positive results. Further, it appears that most of the researchers in this field chase statistical significance with small sample sizes, thus compromising the quality of their conclusions.

Analytical bias accounts for some of the reported effects of tACS on auditory perception.

BACKGROUND: Transcranial alternating current stimulation (tACS) has been shown to modulate auditory, visual, cognitive and motor function. However, tACS effects can often be small and difficult to reproduce. Thus, the establishment of robust experimental and analysis procedures is of high importance. We reviewed the analysis used in six studies that investigated if tACS can phase-modulate auditory perception. All studies used analytical methods that introduce bias and could produce false positive results. Four studies corrected for this bias but two did not. OBJECTIVE: Our objectives were two-fold: 1) Use simulated null hypothesis datasets, where no tACS effect is present, to determine if uncorrected analytical bias could account for some of the reported effects on auditory perception. 2) Help establish best practices to correct for bias when analyzing tACS phase-effects on perception. METHODS: We simulated null hypothesis datasets (i.e. no tACS effect) by drawing samples for all tACS and sham conditions from the same normal distribution. We then applied the reported analyses to the null hypothesis datasets. RESULTS: Reported results from studies that did not correct for analytical bias could be reproduced from the null hypothesis datasets. However, results for studies that did correct for analytical bias could not be reproduced from the null hypothesis datasets. CONCLUSION: True effects of tACS on auditory perception can be detected if analytical bias is accounted for by using correction procedures. However, to fully establish the effects of tACS on auditory perception a reanalysis of the data for the studies that used biased analysis without correction procedures is needed.

The treatment of orofacial pain by using transcranial direct current stimulation.

Neurostimulation methods are used in the treatment of chronic pain, although mainly for pharmacology resistant pain. Transcranial Direct Current Stimulation (tDCS) is a non-invasive neurostimulation method using low direct current (0.029-0.08 mA/cm2) applied to a cathode and anode, which directly stimulates the cranial surface. The applied current causes the most significant changes directly under the electrodes: the cathode reduces the excitability of cortical neurons, whereas the anode increases excitability. The effect of stimulation usually lasts a few hours up to a few days. We observed 19 patients with chronic orofacial pain. Inclusion criteria for the study were the following: orofacial pain, stable analgesic medication for at least one week before the beginning of stimulation and during its course, and age 18-75 years old. Patients with severe organic brain damage or seizure disease (epilepsy) were not included. The most common diagnosis was secondary trigeminal neuralgia after dental surgery. We measured thermal and tactile stimulation on the face before and after tDCS, then at 14 days. The total follow-up period lasted six months. We evaluated pain on a numerical scale (0-10) at each follow-up. We used sets of inventories focused on the examination of pain (a short form of McGill inventory), depression, anxiety, and pain interference with daily activities. tDCS is a non-invasive stimulation technique that is affordable and can be easily administered, especially when compared to other neurostimulation techniques. Only 15 patients out of the total number of 19 responded to the questionnaires.

Swallowing therapy for dysphagia in acute and subacute stroke.

BACKGROUND: Dysphagia (swallowing problems), which is common after stroke, is associated with increased risk of death or dependency, occurrence of pneumonia, poor quality of life, and longer hospital stay. Treatments provided to improve dysphagia are aimed at accelerating recovery of swallowing function and reducing these risks. This is an update of the review first published in 1999 and updated in 2012. OBJECTIVES: To assess the effects of swallowing therapy on death or dependency among stroke survivors with dysphagia within six months of stroke onset. SEARCH METHODS: We searched the Cochrane Stroke Group Trials Register (26 June 2018), the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 6) in the Cochrane Library (searched 26 June 2018), MEDLINE (26 June 2018), Embase (26 June 2018), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (26 June 2018), Web of Science Core Collection (26 June 2018), SpeechBITE (28 June 2016), ClinicalTrials.Gov (26 June 2018), and the World Health Organization International Clinical Trials Registry Platform (26 June 2018). We also searched Google Scholar (7 June 2018) and the reference lists of relevant trials and review articles. SELECTION CRITERIA: We sought to include randomised controlled trials (RCTs) of interventions for people with dysphagia and recent stroke (within six months). DATA COLLECTION AND ANALYSIS: Two review authors independently applied the inclusion criteria, extracted data, assessed risk of bias, used the GRADE approach to assess the quality of evidence, and resolved disagreements through discussion with the third review author (PB). We used random-effects models to calculate odds ratios (ORs), mean differences (MDs), and standardised mean differences (SMDs), and provided 95% confidence intervals (CIs) for each.The primary outcome was functional outcome, defined as death or dependency (or death or disability), at the end of the trial. Secondary outcomes were case fatality at the end of the trial, length of inpatient stay, proportion of participants with dysphagia at the end of the trial, swallowing ability, penetration aspiration score, or pneumonia, pharyngeal transit time, institutionalisation, and nutrition. MAIN RESULTS: We added 27 new studies (1777 participants) to this update to include a total of 41 trials (2660 participants).We assessed the efficacy of swallowing therapy overall and in subgroups by type of intervention: acupuncture (11 studies), behavioural interventions (nine studies), drug therapy (three studies), neuromuscular electrical stimulation (NMES; six studies), pharyngeal electrical stimulation (PES; four studies), physical stimulation (three studies), transcranial direct current stimulation (tDCS; two studies), and transcranial magnetic stimulation (TMS; nine studies).Swallowing therapy had no effect on the primary outcome (death or dependency/disability at the end of the trial) based on data from one trial (two data sets) (OR 1.05, 95% CI 0.63 to 1.75; 306 participants; 2 studies; I² = 0%; P = 0.86; moderate-quality evidence). Swallowing therapy had no effect on case fatality at the end of the trial (OR 1.00, 95% CI 0.66 to 1.52; 766 participants; 14 studies; I² = 6%; P = 0.99; moderate-quality evidence). Swallowing therapy probably reduced length of inpatient stay (MD -2.9, 95% CI -5.65 to -0.15; 577 participants; 8 studies; I² = 11%; P = 0.04; moderate-quality evidence). Researchers found no evidence of a subgroup effect based on testing for subgroup differences (P = 0.54). Swallowing therapy may have reduced the proportion of participants with dysphagia at the end of the trial (OR 0.42, 95% CI 0.32 to 0.55; 1487 participants; 23 studies; I² = 0%; P = 0.00001; low-quality evidence). Trial results show no evidence of a subgroup effect based on testing for subgroup differences (P = 0.91). Swallowing therapy may improve swallowing ability (SMD -0.66, 95% CI -1.01 to -0.32; 1173 participants; 26 studies; I² = 86%; P = 0.0002; very low-quality evidence). We found no evidence of a subgroup effect based on testing for subgroup differences (P = 0.09). We noted moderate to substantial heterogeneity between trials for these interventions. Swallowing therapy did not reduce the penetration aspiration score (i.e. it did not reduce radiological aspiration) (SMD -0.37, 95% CI -0.74 to -0.00; 303 participants; 11 studies; I² = 46%; P = 0.05; low-quality evidence). Swallowing therapy may reduce the incidence of chest infection or pneumonia (OR 0.36, 95% CI 0.16 to 0.78; 618 participants; 9 studies; I² = 59%; P = 0.009; very low-quality evidence). AUTHORS' CONCLUSIONS: Moderate- and low-quality evidence suggests that swallowing therapy did not have a significant effect on the outcomes of death or dependency/disability, case fatality at the end of the trial, or penetration aspiration score. However, swallowing therapy may have reduced length of hospital stay, dysphagia, and chest infections, and may have improved swallowing ability. However, these results are based on evidence of variable quality, involving a variety of interventions. Further high-quality trials are needed to test whether specific interventions are effective.

[Transcranial Direct Current Stimulation (tDCS) : psychiatric use]. / La stimulation électrique transcrânienne (tDCS) : applications en psychiatrie.

Transcranial Direct Current Stimulation (tDCS) is a cheap, easy to use, and relatively safe noninvasive brain stimulation technique. It is increasingly used in several indications in psychiatry and neurology, mainly for depression, chronic pain and cognitive decline due to degenerative brain diseases. Its efficacy is probable in depression and must still be confirmed in numerous other indications. Lowcost devices for the general public are easy to find on the internet and are frequently used for non-therapeutic indications, like the improvement of video gamers' performances. A non-medical use could represent a public health hazard, due to lack of control on stimulation parameters i.e. localization, duration and intensity.

La stimulation électrique trancrânienne à courant direct (tDCS) est une technique de neuromodulation simple d'utilisation, peu coûteuse et présentant très peu d'effets secondaires. Elle connaît une popularité croissante dans une série d'applications en psychiatrie et en neurologie, principalement dans la dépression, les douleurs chroniques et les troubles cognitifs associés à des maladies dégénératives. Son efficacité est probable dans la dépression et doit encore être confirmée dans de nombreuses autres indications. Des appareils bon marché à destination du grand public sont facilement accessibles sur internet et souvent utilisés à des fins non thérapeutiques et de dopage, telles que l'amélioration des performances pour les joueurs de jeux vidéo. Une utilisation sans encadrement médical pourrait représenter un risque de santé publique en raison du non-contrôle des paramètres de stimulation (localisation, durée et intensité).

Non-invasive brain stimulation for negative symptoms in schizophrenia: An updated systematic review and meta-analysis.

BACKGROUND: Schizophrenia is a mental disorder with significant socioeconomic burden. Although current pharmacological treatments are effective for treating positive symptoms, medications have little-to-no effect in the treatment of negative symptoms. OBJECTIVE: To assess the efficacy of non-invasive brain stimulation (NIBS) for negative symptoms in schizophrenia in randomized clinical trials (RCTs). METHODS: A systematic review in Medline and Cochrane Library databases was performed up to May 31, 2017. The primary outcome was Hedges' g for continuous scores in a random-effects model. Heterogeneity was evaluated with the I2 and χ2 tests. Publication bias was assessed using Begg's funnel plot. RESULTS: 31 RCTs (n = 1272) were included, most with small-to-modest sample sizes. Both repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) were superior to sham (Hedges' g = 0.19; 95% CI 0.07-0.32; and 0.5; 0.02-0.97, respectively). Only one study evaluated the use of transcutaneous auricular vagus nerve stimulation (taVNS). The funnel plot and Eggers test showed that the risk of publication bias was low. In relation to heterogeneity, we found an I2 of 0% (p = 0.749) and 51.3% (0.055) for rTMS and tDCS, respectively. CONCLUSION: Both rTMS and tDCS were superior to sham stimulation for ameliorating negative symptoms in schizophrenia. We found no considerable heterogeneity or publication bias in our analysis, corroborating the strength of our findings. Not enough studies on other NIBS techniques, such as taVNS, were found for an isolated analysis. Further RCTs with larger sample sizes are needed to clarify the specific impact of NIBS on negative symptoms in schizophrenia.

Feasibility and Clinical Utility of High-definition Transcranial Direct Current Stimulation in the Treatment of Persistent Hallucinations in Schizophrenia.

Persistent auditory verbal hallucination is a clinically significant problem in schizophrenia. Recent studies suggest a promising role for add-on transcranial direct current stimulation (tDCS) in treatment. An optimised version of tDCS, namely high-definition tDCS (HD-tDCS), uses smaller electrodes arranged in a 4x1 ring configuration and may offer more focal and predictable neuromodulation than conventional tDCS. This case report illustrates the feasibility and clinical utility of add-on HD-tDCS over the left temporoparietal junction in a 4x1 ring configuration to treat persistent auditory verbal hallucination in schizophrenia.

A Systematic Review and Meta-Analysis of the Effects of Transcranial Direct Current Stimulation (tDCS) Over the Dorsolateral Prefrontal Cortex in Healthy and Neuropsychiatric Samples: Influence of Stimulation Parameters.

BACKGROUND: Research into the effects of transcranial direct current stimulation of the dorsolateral prefrontal cortex on cognitive functioning is increasing rapidly. However, methodological heterogeneity in prefrontal tDCS research is also increasing, particularly in technical stimulation parameters that might influence tDCS effects. OBJECTIVE: To systematically examine the influence of technical stimulation parameters on DLPFC-tDCS effects. METHODS: We performed a systematic review and meta-analysis of tDCS studies targeting the DLPFC published from the first data available to February 2016. Only single-session, sham-controlled, within-subject studies reporting the effects of tDCS on cognition in healthy controls and neuropsychiatric patients were included. RESULTS: Evaluation of 61 studies showed that after single-session a-tDCS, but not c-tDCS, participants responded faster and more accurately on cognitive tasks. Sub-analyses specified that following a-tDCS, healthy subjects responded faster, while neuropsychiatric patients responded more accurately. Importantly, different stimulation parameters affected a-tDCS effects, but not c-tDCS effects, on accuracy in healthy samples vs. PATIENTS: increased current density and density charge resulted in improved accuracy in healthy samples, most prominently in females; for neuropsychiatric patients, task performance during a-tDCS resulted in stronger increases in accuracy rates compared to task performance following a-tDCS. CONCLUSIONS: Healthy participants respond faster, but not more accurate on cognitive tasks after a-tDCS. However, increasing the current density and/or charge might be able to enhance response accuracy, particularly in females. In contrast, online task performance leads to greater increases in response accuracy than offline task performance in neuropsychiatric patients. Possible implications and practical recommendations are discussed.

A systematic review of the clinical efficacy of transcranial direct current stimulation (tDCS) in psychiatric disorders.

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique, which can be used to selectively disrupt patterns of neural activity that are associated with symptoms of mental illness. tDCS has been implemented in numerous therapeutic trials across a range of patient populations, with a rapidly increasing number of studies being published each year. This systematic review aimed to evaluate the efficacy of tDCS in the treatment of psychiatric disorders. Four electronic databases were searched from inception until December 2015 by two independent reviewers, and 66 eligible studies were identified. Depression was the most extensively researched condition, followed by schizophrenia and substance use disorders. Data on obsessive compulsive disorder, generalised anxiety disorder, and anorexia nervosa were also obtained. The quality of included studies was appraised using a standardised assessment framework, which yielded a median score corresponding to "weak" on the three-point scale. This improved to "moderate" when case reports/series were excluded from the analysis. Overall, data suggested that tDCS interventions comprising multiple sessions can ameliorate symptoms of several major psychiatric disorders, both acutely and in the long-term. Nevertheless, the tDCS field is still in its infancy, and several methodological and ethical issues must be addressed before clinical efficacy can truly be determined. Studies probing the mechanisms of action of tDCS and those facilitating the definition of optimised stimulation protocols are warranted. Furthermore, evidence from large-scale, multi-centre randomised controlled trials is required if the transition of this therapy from the laboratory to the clinic is to be considered.

Intraoperative Spinal Cord and Nerve Root Monitoring: A Hospital Survey and Review.

Intraoperative monitoring (IOM) of spinal cord and nerve root injury through somatosensory evoked potentials (SSEP), transcranial motor evoked potentials (TcMEP), spontaneous electromyography (sEMG), and triggered electromyography (tEMG) modalities is vital during spinal surgery. However, there are currently no practice guidelines or practice patterns for the utilization of unimodal and multimodal IOM for specific surgeries. This study reviews IOM modalities and documents practice patterns of spine surgeons at our single-center tertiary hospital about their use of various IOM modalities on 23 spinal procedures. As different intraoperative monitoring modalities have shown to have different sensitivities and specificities, devising practice guidelines for IOM utilization in specific spinal procedures should be considered.

Outside access: advances in tDCS could provide a mainstream clinical tool for noninvasive neuromodulation.

A treatment for depression, chronic pain, cravings, and more--this is the emerging field of transcranial direct current stimulation (tDCS). In tDCS, transcranial means through the skull, and direct current is a weak stimulation current delivered to the brain using noninvasive electrodes placed on the scalp [Figure 1(a)].

Theoretical Analysis of the Effect of Temperature on Current Delivery to the Brain During tDCS.

BACKGROUND: Transcranial direct current simulation (tDCS) is a non-invasive neuromodulation technique that has become increasingly popular as a potential therapeutic method for a variety of brain disorders. Since the treatment outcome may depend on the current density delivered to the brain cortical region, a significant challenge is to control the current dose reaching the cortical region. OBJECTIVE AND METHODS: This study aims to investigate the effect of temperature on current delivery to the brain. We devised a method for modulating the amount of current delivered to the brain by changing the temperature of the scalp. We developed analytical and numerical models that describe the relationship between temperature and electrical properties of the scalp based on the following mechanisms: ion mobility and blood perfusion in scalp. RESULTS AND CONCLUSIONS: The current delivery to brain was investigated by changing the temperature between two electrodes that are attached to the surface of the scalp, within a tolerable physiological range. Results show that by increasing the temperature between two electrodes, a higher portion of current is shunted via the scalp and the proportion of the current that penetrates the scalp and skull into brain is decreased. On the other hand, cooling the area between two electrodes on the scalp increases the current delivery to the cortical region of the brain. Our results show that cooling the scalp during tDCS can be considered as a possible way to effectively control the current delivery to the brain and increase the efficacy of tDCS.

Neuromodulation research and application in the U.S. Department of Defense.

BACKGROUND: Modern neuromodulatory techniques for military applications have been explored for the past decade, with an intent to optimize operator performance and, ultimately, to improve overall military effectiveness. In light of potential military applications, some researchers have voiced concern about national security agency involvement in this area of research, and possible exploitation of research findings to support military objectives. The aim of this article is to examine the U.S. Department of Defense's interest in and application of neuromodulation. METHODS: We explored articles, cases, and historical context to identify critical considerations of debate concerning dual use (i.e., national security and civilian) technologies, specifically focusing on non-invasive brain stimulation (NIBS). DISCUSSION: We review the background and recent examples of DoD-sponsored neuromodulation research, framed in the more general context of research that aims to optimize and/or rehabilitate human performance. We propose that concerns about military exploitation of neuromodulatory science and technology are not unique, but rather are part of a larger philosophic debate pertaining to military application of human performance science and technology. We consider unique aspects of the Department of Defense research enterprise--which includes programs crucial to the advancement of military medicine--and why it is well-situated to fund and perform such research. We conclude that debate concerning DoD investment in human performance research must recognize the significant potential for dual use (civilian, medical) benefit as well as the need for civilian scientific insight and influence. Military interests in the health and performance of service members provide research funding and impetus to dual use applications that will benefit the civilian community.