Why the fuck ARE YOU JUST 'IMPROVING' RECOVERY, RATHER THAT ACTIALLY DELIVERING 100% RECOVERY? You've never actually talked to a survivor about their wants? Just maybe you'll want that recovery when you become the 1 in 4 per WHO that has a stroke!). I'd suggest you start working on that now!
Patient-tailored transcranial direct current stimulation to improve stroke rehabilitation: study protocol of a randomized sham-controlled trial
Trials 24, Article number: 216 (2023)
Abstract
Background
Many patients do not fully regain motor function after ischemic stroke. Transcranial direct current stimulation (TDCS) targeting the motor cortex may improve(NOT GOOD ENOUGH!)motor outcome as an add-on intervention to physical rehabilitation. However, beneficial effects on motor function vary largely among patients within and across TDCS trials. In addition to a large heterogeneity of study designs, this variability may be caused by the fact that TDCS was given as a one-size-fits-all protocol without accounting for anatomical differences between subjects. The efficacy and consistency of TDCS might be improved by a patient-tailored design that ensures precise targeting of a physiologically relevant area with an appropriate current strength.
Methods
In a randomized, double-blinded, sham-controlled trial, patients with subacute ischemic stroke and residual upper-extremity paresis will receive two times 20 min of focal TDCS of ipsilesional primary motor hand area (M1-HAND) during supervised rehabilitation training three times weekly for 4 weeks. Anticipated 60 patients will be randomly assigned to active or sham TDCS of ipsilesional M1-HAND, using a central anode and four equidistant cathodes. The placement of the electrode grid on the scalp and current strength at each cathode will be personalized based on individual electrical field models to induce an electrical current of 0.2 V/m in the cortical target region resulting in current strengths between 1 and 4 mA. Primary endpoint will be the difference in change of Fugl-Meyer Assessment of Upper Extremity (FMA-UE) score between active TDCS and sham at the end of the intervention. Exploratory endpoints will include UE-FMA at 12 weeks. Effects of TDCS on motor network connectivity and interhemispheric inhibition will be assessed with functional MRI and transcranial magnetic stimulation.
Discussion
The study will show the feasibility and test the efficacy of personalized, multi-electrode anodal TDCS of M1-HAND in patients with subacute stroke patients with upper-extremity paresis. Concurrent multimodal brain mapping will shed light into the mechanisms of action of therapeutic personalized TDCS of M1-HAND. Together, the results from this trial may inform future personalized TDCS studies in patients with focal neurological deficits after stroke.
Introduction
Background and rationale
Ischemic stroke (IS) remains a global challenge and two-thirds of stroke patients show continued motor deficits which impact activities of daily living and quality of life [1]. Early-initiated rehabilitation training is central to recovery of motor function after IS [2, 3]. Transcranial brain stimulation (TBS) as an add-on to neurorehabilitation in the early subacute phase after IS (within the first 4 weeks after stroke onset) might result in faster and better recovery by optimizing the underlying neuroplastic processes, which may be more susceptible during the subacute phase post-stroke [4]. However, the use of a TBS technique to improve rehabilitation has to be feasible for patients and implementable in a clinical setting.
Transcranial direct current stimulation (TDCS) has been tested as a non-invasive tool to improve neurorehabilitation. The electric currents that TDCS can induce in the cortex through scalp electrodes result in a minor shift in the membrane potential and thereby a modification of the intrinsic neuronal network activity [5,6,7]. The pyramidal neurons in the area located under the anodal electrode are suggested to increase in excitability through depolarization of both the soma and the afferent axons while the pyramidal neurons located under the cathodal electrode decrease in excitability through hyperpolarization of the soma and afferent axons [8, 9]. These modulations in the membrane potential are thought to modulate behavior [10] and enhance neural plasticity by stimulating synaptic connections and long-term potentiation processes [11, 12].
Previous clinical trials have demonstrated that TDCS of the primary motor cortex (M1) may improve upper-extremity function in both subacute and chronic stroke patients, when applied concurrent with rehabilitation training. Ipsilesional anodal TDCS with the traditional montage of two square electrodes have been most widely examined [13,14,15], but contra-lesional cathodal TDCS [16, 17] and dual-TDCS [18] also has been studied. Across these studies, TDCS was applied to target the hand region of the primary motor cortex (M1-HAND) of either the healthy or the affected hemisphere, and current intensity is usually fixed between 1 and 2 mA across all subjects. However, according to meta-literature, up to 50% of patients are non-responders to the intervention [19], and only limited evidence of a significantly increased effect of TDCS compared to sham regarding upper-extremity rehabilitation [20,21,22]. Such lack of effects may associate to the one-size-fits-all approach which might miss the area thought to be targeted by TDCS (e.g., M1) both regarding location and current strength necessary to induce shifts in the membrane potential of the neurons in the target area. In addition, TDCS is often combined with either robot-assisted rehabilitation [22] or virtual reality [23] which may further confound the interpretation of the results.
Using individual magnetic resonance imaging (MRI) scans, electric field modeling enables a precise estimation of the electric field distribution in the brain during transcranial electrical brain stimulation and an optimization of electrode placement and dosing of interventional TDCS [24,25,26,27].
Patients with post-stroke upper extremity disability show an impaired motor network structure including a reduced excitatory influence from pre-motor brain areas and disinhibition of the contra-lesional M1-HAND [28, 29]. The interhemispheric imbalance between precentral motor cortices tends to improve with motor recovery and is often completely restored in patients with full recovery [28,29,30]. It is however unclear whether this imbalance facilitates or hinders motor recovery [29, 31].
Objectives
The main hypothesis of this study is that patient-tailored anodal TDCS targeting the ipsilesional M1-HAND during supervised upper extremity training will result in greater improvements in upper-extremity function, measured by difference in change in FMA-UE score, compared to sham stimulation. It is furthermore hypothesized that patient-tailored TDCS is feasible to use for stroke rehabilitation in a stroke unit at a hospital setting.
Additionally, it is hypothesized that motor improvements correlate with the degree of normalization of functional motor connectivity and interhemispheric inhibitory interaction as revealed by task-related functional MRI and TMS. We will also assess the degree of corticospinal tract (CST) integrity measured by transcranial magnetic stimulation (TMS) and diffusion-weighted MRI (DWI) to explore how structural impairment in the corticospinal tract relates to the efficacy of anodal TDCS.
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