Moving Forward by Stimulating the Brain: Transcranial Direct Current Stimulation in Post-Stroke Hemiparesis

I don't give a shit about the mechanisms of tDCS, motor learning and neuroplasticity. It is very fucking simple, write up repeatable stroke protocols. Survivors want to know exactly how to recover, they don't care about the big words you are using to impress your colleagues.
http://journal.frontiersin.org/article/10.3389/fnhum.2016.00394/full?

Heather T. Peters^1,2*, Dylan J. Edwards^3,4, Susan Wortman-Jutt⁵ and Stephen J. Page^1,2

• ¹Division of Occupational Therapy, The Ohio State University, Columbus, OH, USA
• ²Better Rehabilitation and Assessment for Improved Neuro-recovery (B.R.A.I.N.) Laboratory, Ohio State University, Columbus, OH, USA
• ³Laboratory for Non-Invasive Brain Stimulation and Human Motor Control, The Burke Medical Research Institute, White Plains, NY, USA
• ⁴Department of Neurology, Weill Cornell Medical College, White Plains, NY, USA
• ⁵Burke Rehabilitation Hospital, White Plains, NY, USA

Stroke remains a leading cause of disability worldwide, with a majority of survivors experiencing long term decrements in motor function that severely undermine quality of life. While many treatment approaches and adjunctive strategies exist to remediate motor impairment, many are only efficacious or feasible for survivors with active hand and wrist function, a population who constitute only a minority of stroke survivors. Transcranial direct current stimulation (tDCS), a type of non-invasive brain stimulation, has been increasingly utilized to increase motor function following stroke as it is able to be used with stroke survivors of varying impairment levels, is portable, is relatively inexpensive and has few side effects and contraindications. Accordingly, in recent years the number of studies investigating its efficacy when utilized as an adjunct to motor rehabilitation regimens has drastically increased. While many of these trials have reported positive and promising efficacy, methodologies vary greatly between studies, including differences in stimulation parameters, outcome measures and the nature of physical practice. As such, an urgent need remains, centering on the need to investigate these methodological differences and synthesize the most current evidence surrounding the application of tDCS for post-stroke motor rehabilitation. Accordingly, the purpose of this paper is to provide a detailed overview of the most recent tDCS literature (published 2014-2015), while highlighting these variations in methodological approach, as well to elucidate the mechanisms associated with tDCS and post-stroke motor re-learning and neuroplasticity.

Many stroke survivors exhibit hemiparesis, which undermines independence and quality of life (Mayo et al., 2002). Several rehabilitative approaches targeting hemiparetic limbs have been developed (Page et al., 2013a,b) with most incorporating task-specific physical practice of the paretic limb. These approaches attempt to exploit surviving brain tissue and, specifically, to modulate synaptic networks and strengthen connections subserving these networks. While such regimens demonstrate promise, these brain processes can be difficult to modulate with a high precision and consistency when physical practice is the singular method applied.

The therapeutic application of electrical currents to the brain has been documented for centuries (Nitsche et al., 2008), with its use becoming more clinically-plausible through the introduction of the electrical battery in the eighteenth century. In subsequent decades, brain stimulation was successfully applied for a variety of psychological disorders (Kubera et al., 2015; Xie et al., 2015), as well as pain (Ma et al., 2015). More recently, transcranial direct current stimulation (tDCS)—non-invasive brain stimulation administering a constant, low current—has been used to facilitate neurophysiological (Nitsche and Paulus, 2000) and motor changes in post-stroke hemiparesis (Butler et al., 2013). tDCS offers the additional advantage of being portable, relatively inexpensive, and straightforward in administration. As a treatment for targeting post-stroke motor impairments, tDCS can enhance or suppress brain excitability with great focality and over prolonged periods, which constitutes decided benefits over physical therapy alone.

The continued prevalence and impact of stroke-induced hemiparesis suggests a need to evaluate the efficacy of tDCS as an adjuvant to physical therapy for post-stroke motor rehabilitation. In recent years, the number of studies utilizing tDCS alongside a variety of physical rehabilitation regimens has drastically increased. While results from these trials are promising, methodologies vary greatly in terms of the nature of physical practice, stimulation montage and type of outcome measures, among other important factors. There is an urgent need to highlight these methodological differences and provide a snapshot of the most current evidence surrounding the application of tDCS for post-stroke motor rehabilitation. This paper provides an overview of recent tDCS literature (published 2014-2015), with an emphasis on methodological approach, as well a description of the mechanisms associated with tDCS and post-stroke motor re-learning and neuroplasticity.