Dataset Information

Safety of Transcranial Direct Current Stimulation: Evidence Based Update 2016.

ABSTRACT: This review updates and consolidates evidence on the safety of transcranial Direct Current Stimulation (tDCS). Safety is here operationally defined by, and limited to, the absence of evidence for a Serious Adverse Effect, the criteria for which are rigorously defined. This review adopts an evidence-based approach, based on an aggregation of experience from human trials, taking care not to confuse speculation on potential hazards or lack of data to refute such speculation with evidence for risk. Safety data from animal tests for tissue damage are reviewed with systematic consideration of translation to humans. Arbitrary safety considerations are avoided. Computational models are used to relate dose to brain exposure in humans and animals. We review relevant dose-response curves and dose metrics (e.g. current, duration, current density, charge, charge density) for meaningful safety standards. Special consideration is given to theoretically vulnerable populations including children and the elderly, subjects with mood disorders, epilepsy, stroke, implants, and home users. Evidence from relevant animal models indicates that brain injury by Direct Current Stimulation (DCS) occurs at predicted brain current densities (6.3-13?A/m(2)) that are over an order of magnitude above those produced by conventional tDCS. To date, the use of conventional tDCS protocols in human trials (?40?min, ?4?milliamperes, ?7.2 Coulombs) has not produced any reports of a Serious Adverse Effect or irreversible injury across over 33,200 sessions and 1000 subjects with repeated sessions. This includes a wide variety of subjects, including persons from potentially vulnerable populations.

SUBMITTER: Bikson M

PROVIDER: S-EPMC5007190 | biostudies-literature | 2016 Sep-Oct

REPOSITORIES: biostudies-literature

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Safety of Transcranial Direct Current Stimulation: Evidence Based Update 2016.

Bikson Marom M Grossman Pnina P Thomas Chris C Zannou Adantchede Louis AL Jiang Jimmy J Adnan Tatheer T Mourdoukoutas Antonios P AP Kronberg Greg G Truong Dennis D Boggio Paulo P Brunoni André R AR Charvet Leigh L Fregni Felipe F Fritsch Brita B Gillick Bernadette B Hamilton Roy H RH Hampstead Benjamin M BM Jankord Ryan R Kirton Adam A Knotkova Helena H Liebetanz David D Liu Anli A Loo Colleen C Nitsche Michael A MA Reis Janine J Richardson Jessica D JD Rotenberg Alexander A Turkeltaub Peter E PE Woods Adam J AJ

Brain stimulation 20160615 5

This review updates and consolidates evidence on the safety of transcranial Direct Current Stimulation (tDCS). Safety is here operationally defined by, and limited to, the absence of evidence for a Serious Adverse Effect, the criteria for which are rigorously defined. This review adopts an evidence-based approach, based on an aggregation of experience from human trials, taking care not to confuse speculation on potential hazards or lack of data to refute such speculation with evidence for risk. ...[more]

PMID: 27372845

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Project description:Introduction: Conventional transcranial direct current stimulation (tDCS) and high-definition tDCS (HD-tDCS) may improve motor learning in children. Mechanisms are not understood. Neuronavigated robotic transcranial magnetic stimulation (TMS) can produce individualised maps of primary motor cortex (M1) topography. We aimed to determine the effects of tDCS- and HD-tDCS-enhanced motor learning on motor maps. Methods: Typically developing children aged 12-18 years were randomised to right M1 anodal tDCS, HD-tDCS, or Sham during training of their left-hand on the Purdue Pegboard Task (PPT) over 5 days. Bilateral motor mapping was performed at baseline (pre), day 5 (post), and 6-weeks retention time (RT). Primary muscle was the first dorsal interosseous (FDI) with secondary muscles of abductor pollicis brevis (APB) and adductor digiti minimi (ADM). Primary mapping outcomes were volume (mm2/mV) and area (mm2). Secondary outcomes were centre of gravity (COG, mm) and hotspot magnitude (mV). Linear mixed-effects modelling was employed to investigate effects of time and stimulation type (tDCS, HD-tDCS, Sham) on motor map characteristics. Results: Twenty-four right-handed participants (median age 15.5 years, 52% female) completed the study with no serious adverse events or dropouts. Quality maps could not be obtained in two participants. No effect of time or group were observed on map area or volume. LFDI COG (mm) differed in the medial-lateral plane (x-axis) between tDCS and Sham (p = 0.038) from pre-to-post mapping sessions. Shifts in map COG were also observed for secondary left-hand muscles. Map metrics did not correlate with behavioural changes. Conclusion: Robotic TMS mapping can safely assess motor cortex neurophysiology in children undergoing motor learning and neuromodulation interventions. Large effects on map area and volume were not observed while changes in COG may occur. Larger controlled studies are required to understand the role of motor maps in interventional neuroplasticity in children.

Project description:BackgroundTranscranial direct current stimulation (tDCS) is a form of noninvasive brain stimulation that has shown improved adult stroke outcomes. Applying tDCS in children with congenital hemiparesis has not yet been explored.ObjectiveThe primary objective of this study was to explore the safety and feasibility of single-session tDCS through an adverse events profile and symptom assessment within a double-blind, randomized placebo-controlled preliminary study in children with congenital hemiparesis. A secondary objective was to assess the stability of hand and cognitive function.DesignA double-blind, randomized placebo-controlled pretest/posttest/follow-up study was conducted.SettingThe study was conducted in a university pediatric research laboratory.ParticipantsThirteen children, ages 7 to 18 years, with congenital hemiparesis participated.MeasurementsAdverse events/safety assessment and hand function were measured.InterventionParticipants were randomly assigned to either an intervention group or a control group, with safety and functional assessments at pretest, at posttest on the same day, and at a 1-week follow-up session. An intervention of 10 minutes of 0.7 mA tDCS was applied to bilateral primary motor cortices. The tDCS intervention was considered safe if there was no individual decline of 25% or group decline of 2 standard deviations for motor evoked potentials (MEPs) and behavioral data and no report of adverse events.ResultsNo major adverse events were found, including no seizures. Two participants did not complete the study due to lack of MEP and discomfort. For the 11 participants who completed the study, group differences in MEPs and behavioral data did not exceed 2 standard deviations in those who received the tDCS (n=5) and those in the control group (n=6). The study was completed without the need for stopping per medical monitor and biostatisticial analysis.LimitationsA limitation of the study was the small sample size, with data available for 11 participants.ConclusionsBased on the results of this study, tDCS appears to be safe, feasible, and well tolerated in most children with hemiparesis. Future investigations of serial sessions of tDCS in conjunction with rehabilitation in pediatric hemiparesis are indicated to explore the benefit of a synergistic approach to improving hand function.

Project description:Background: In transcranial direct current stimulation (tDCS), the injected current becomes distributed across the brain areas. The objective is to stimulate the target region of interest (ROI) while minimizing the current in non-target ROIs (the 'focality' of tDCS). For this purpose, determining the appropriate current dose for an individual is difficult. Aim: To introduce a dose-target determination index (DTDI) to quantify the focality of tDCS and examine the dose-focality relationship in three different populations. Method: Here, we extended our previous toolbox i-SATA to the MNI reference space. After a tDCS montage is simulated for a current dose, the i-SATA(MNI) computes the average (over voxels) current density for every region in the brain. DTDI is the ratio of the average current density at the target ROI to the ROI with a maximum value (the peak region). Ideally, target ROI should be the peak region, so DTDI shall range from 0 to 1. The higher the value, the better the dose. We estimated the variation of DTDI within and across individuals using T1-weighted brain images of 45 males and females distributed equally across three age groups: (a) young adults (20 ≤ x ˂ 40 years), (b) mid adults (40 ≤ x ˂ 60 years), and (c) older adults (60 ≤ x ˂ 80 years). DTDI's were evaluated for the frontal montage with electrodes at F3 and the right supraorbital for three current doses of 1 mA, 2 mA, and 3 mA, with the target ROI at the left middle frontal gyrus. Result: As the dose is incremented, DTDI may show (a) increase, (b) decrease, and (c) no change across the individuals depending on the relationship (nonlinear or linear) between the injected tDCS current and the distribution of current density in the target ROI. The nonlinearity is predominant in older adults with a decrease in focality. The decline is stronger in males. Higher current dose at older age can enhance the focality of stimulation. Conclusion: DTDI provides information on which tDCS current dose will optimize the focality of stimulation. The recommended DTDI dose should be prioritized based on the age (>40 years) and sex (especially for males) of an individual. The toolbox i-SATA(MNI) is freely available.

Dataset Information

Safety of Transcranial Direct Current Stimulation: Evidence Based Update 2016.

Publications

Safety of Transcranial Direct Current Stimulation: Evidence Based Update 2016.

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