Intensity Dependent Effects of Transcranial Direct Current Stimulation on Corticospinal Excitability in Chronic Spinal Cord Injury

Murray, Lynda M.; Edwards, Dylan; Ruffini, Giulio; Labar, Douglas; Stampas, Argyrios; Pascual‐Leone, Álvaro; Cortes, Mar

doi:10.1016/j.apmr.2014.11.004

Cited by 57 publications

(57 citation statements)

References 56 publications

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“…No significant differences were found when we compared the after-effects of condition 2mA vs. 1mA. However, in accordance with previous investigations [43, 47] we observed higher MEP amplitudes after 2mA for all three sessions. Consequently, we concluded that 2mA-atDCS induces a more consistent group excitatory response than 1mA-atDCS across repeated sessions when applied with at least 48 hours apart.…”

Section: Discussionsupporting

confidence: 91%

Response variability of different anodal transcranial direct current stimulation intensities across multiple sessions

2017

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Background It is well known that transcranial direct current stimulation (tDCS) is capable of modulating corticomotor excitability. However, a source of growing concern has been the observed inter- and intra-individual variability of tDCS-responses. Recent studies have assessed whether individuals respond in a predictable manner across repeated sessions of anodal tDCS (atDCS). The findings of these investigations have been inconsistent, and their methods have some limitations (i.e. lack of sham condition or testing only one tDCS intensity). Objective To study inter- and intra-individual variability of atDCS effects at two different intensities on primary motor cortex (M1) excitability. Methods Twelve subjects participated in a crossover study testing 7-min atDCS over M1 in three separate conditions (2mA, 1mA, sham) each repeated three times separated by 48hrs. Motor evoked potentials were recorded before and after stimulation (up to 30min). Time of testing was maintained consistent within participants. To estimate the reliability of tDCS effects across sessions, we calculated the Intra-class Correlation Coefficient (ICC). Results AtDCS at 2mA, but not 1mA, significantly increased cortical excitability at the group level in all sessions. The overall ICC revealed fair to high reliability of tDCS effects for multiple sessions. Given that the distribution of responses showed important variability in the sham condition, we established a Sham Variability-Based Threshold to classify responses and to track individual changes across sessions. Using this threshold an intra-individual consistent response pattern was then observed only for the 2mA condition. Conclusion 2mA anodal tDCS results in consistent intra- and inter-individual increases of M1 excitability.

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Section: Discussionsupporting

confidence: 91%

Response variability of different anodal transcranial direct current stimulation intensities across multiple sessions

2017

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“…Borckardt et al, 2012; Faria et al, 2012; Murray et al, 2015). Twenty minutes of real ( n = 13) or sham ( n = 11) 2 mA HD-tDCS over the motor cortex using 1 cm 2 electrodes (Borckardt et al, 2012) or 3 × 20 min sessions with 1–2 mA using 3 cm 2 PiStim electrodes (hybrid Ag/AgCl EEG/tDCS electrodes with a circular contact area, Starstim, Neuroelectrics) (Murray et al, 2015) resulted in no AEs.…”

Section: Electrode Design For Tesmentioning

confidence: 99%

“…The most common reported AEs were mild sensory phenomena that only occurred during stimulation at or near the electrodes (tingling, itching, phosphenes) that occurred in 253 (11.2%) subjects (e.g., Grecco et al, 2014a; Triccas et al, 2015). Transient events included skin irritation (75 subjects; 3.3%, Ferrucci et al, 2014; Triccas et al, 2015), issues with sleep or energy level, including sleepiness, fatigue, and insomnia (74 subjects; 3.3%; e.g., Lesniak et al, 2014; Murray et al, 2015), headache or nausea (56 subjects; 2.5%; Khedr et al, 2014; Kim et al, 2014), problems with concentrating (15 subjects; 0.7%; e.g., Wrigley et al, 2013), and neck pain (4 subjects; 0.2%; e.g. Straudi et al, 2016).…”

Section: The Application Of Low Intensity Tes In Human Studies: Aementioning

confidence: 99%

Low intensity transcranial electric stimulation: Safety, ethical, legal regulatory and application guidelines

Antal

Alekseichuk

Bikson

et al. 2017

Clinical Neurophysiology

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Low intensity transcranial electrical stimulation (TES) in humans, encompassing transcranial direct current (tDCS), transcutaneous spinal Direct Current Stimulation (tsDCS), transcranial alternating current (tACS), and transcranial random noise (tRNS) stimulation or their combinations, appears to be safe. No serious adverse events (SAEs) have been reported so far in over 18,000 sessions administered to healthy subjects, neurological and psychiatric patients, as summarized here. Moderate adverse events (AEs), as defined by the necessity to intervene, are rare, and include skin burns with tDCS due to suboptimal electrode-skin contact. Very rarely mania or hypomania was induced in patients with depression (11 documented cases), yet a causal relationship is difficult to prove because of the low incidence rate and limited numbers of subjects in controlled trials. Mild AEs (MAEs) include headache and fatigue following stimulation as well as prickling and burning sensations occurring during tDCS at peak-to-baseline intensities of 1–2 mA and during tACS at higher peak-to-peak intensities above 2 mA. The prevalence of published AEs is different in studies specifically assessing AEs vs. those not assessing them, being higher in the former. AEs are frequently reported by individuals receiving placebo stimulation. The profile of AEs in terms of frequency, magnitude and type is comparable in healthy and clinical populations, and this is also the case for more vulnerable populations, such as children, elderly persons, or pregnant women. Combined interventions (e.g., co-application of drugs, electrophysiological measurements, neuroimaging) were not associated with further safety issues. Safety is established for low-intensity ‘conventional’ TES defined as <4 mA, up to 60 min duration per day. Animal studies and modeling evidence indicate that brain injury could occur at predicted current densities in the brain of 6.3–13 A/m2 that are over an order of magnitude above those produced by tDCS in humans. Using AC stimulation fewer AEs were reported compared to DC. In specific paradigms with amplitudes of up to 10 mA, frequencies in the kHz range appear to be safe. In this paper we provide structured interviews and recommend their use in future controlled studies, in particular when trying to extend the parameters applied. We also discuss recent regulatory issues, reporting practices and ethical issues. These recommendations achieved consensus in a meeting, which took place in Göttingen, Germany, on September 6–7, 2016 and were refined thereafter by email correspondence.

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“…As closing articles for this issue, we present application of rTMS and tDCS in rehabilitation of spinal cord injury (SCI), a condition that presumably ‘spares’ the brain. Still, Murray et al 47 . and Tazoe and Perez 48 argue that motor cortex and its corticospinal tracts may be promising anatomical substrates following incomplete SCI because muscles below the lesion, albeit weak, may still exhibit viable corticospinal response as sensorimotor cortices exhibit tremendous reorganization.…”

Section: What Is Non-invasive Brain Stimulation?mentioning

confidence: 99%

It Takes Two: Noninvasive Brain Stimulation Combined With Neurorehabilitation

Page

Cunningham

Plow

et al. 2015

Archives of Physical Medicine and Rehabilitation

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The goal of post-acute neurorehabilitation is to maximize patients' function, ideally by using surviving brain and central nervous system tissue when possible. Yet the structures incorporated into neurorehabilitative approaches often differ from this target, which may explain why efficacy of conventional clinical treatments targeting neurological impairments varies widely. Non-invasive brain stimulation such as with Transcranial Magnetic Stimulation (TMS) and transcranial direct current stimulation (tDCS) offers the possibility of directly targeting brain structures to facilitate or inhibit their activity so as to steer neural plasticity in recovery, and measure neuronal output and interactions for evaluating progress. Latest advances as stereotactic navigation and electric field modeling are enabling more precise targeting of patient's residual structures in diagnosis and therapy. Given its promise, this supplement illustrates the wide-ranging significance of TMS and tDCS in neurorehabilitation, including in stroke, pediatrics, traumatic brain injury, focal hand dystonia, neuropathic pain and spinal cord injury. TMS and tDCS are still not widely used and remain poorly understood in neurorehabilitation. Thus, the present supplement includes articles that highlight ready clinical application of these technologies, including their comparative diagnostic capabilities relative to neuroimaging, their therapeutic benefit, their optimal delivery, the stratification of likely responders, and the variable benefits associated with their clinical use due to interactions between pathophysiology and the innate reorganization of the patient's brain. Overall, the supplement concludes that whether provided in isolation or in combination, non-invasive brain stimulation with neuro-rehabilitation are synergistic in the potential to transform clinical practice.

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Intensity Dependent Effects of Transcranial Direct Current Stimulation on Corticospinal Excitability in Chronic Spinal Cord Injury

Cited by 57 publications

References 56 publications

Response variability of different anodal transcranial direct current stimulation intensities across multiple sessions

Response variability of different anodal transcranial direct current stimulation intensities across multiple sessions

Low intensity transcranial electric stimulation: Safety, ethical, legal regulatory and application guidelines

It Takes Two: Noninvasive Brain Stimulation Combined With Neurorehabilitation

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