And you somehow think this is of any use at all when delivery of cathodal tDCS is needed 30 minutes after stroke onset?
Effect of Cathodal Transcranial Direct Current Stimulation for Lower Limb Subacute Stroke Rehabilitation
Abstract
Background and Purpose.
Motor dysfunction of the lower limb is a common sequela in stroke patients. The aim was to evaluate the efficacy of cathodal transcranial direct current stimulation (ctDCS) combined with conventional gait rehabilitation (CGR) to compare and clarify the clinical rehabilitation efficacy of ctDCS on motor dysfunction of the lower limbs after stroke to improve the walking ability of stroke patients.
Methods.
A pilot double-blind and randomized clinical trial. Ninety-one subjects with subacute stroke were treated with cathodal/sham stimulation tDCS based on CGR (physiotherapy 40 min/d and occupational therapy 20 min/d) once daily for 20 consecutive working days. Computer-based stratified randomization (1 : 1) was employed by considering age and sex, with concealed assignments in opaque envelopes to ensure no allocation errors after disclosure at the study’s end. Patients were evaluated at T0 before treatment, T1 immediately after the posttreatment assessment, and T2 assessment one month after the end of the treatment. The primary outcome index was assessed: lower limb Fugl-Meyer motor score (FMA-LE); secondary endpoints were other gait assessment and relevant stroke scale assessment.
Results.
Patients in the trial group performed significantly better than the control group in all primary outcome indicators assessed post treatment T1 and at follow-up T2: FMA-LE outcome indicators between the two groups in T1 (P=0.032; effect size 1.00, 95% CI: 0.00 to 2.00) and FMA-LE outcome indicators between the two groups in T2 (P=0.010; effect size 2.00, 95% CI: 1.00 to 3.00).
Conclusion.
In the current pilot study, ctDCS plus CGR was an effective treatment modality to improve lower limb motor function with subacute stroke. The effectiveness of cathodal tDCS in poststroke lower limb motor dysfunction is inconclusive. Therefore, a large randomized controlled trial is needed to verify its effectiveness.
1. Introduction
Stroke is the third leading cause of disability worldwide, resulting in permanent disability in 15% to 30% of survivors. Gait balance dysfunction is the most common complication in stroke patients, and it is estimated that more than 50% of hemiplegic patients are left with lower limb gait balance dysfunction, which causes falls, increases the risk of trauma, affects independence in daily life, and increases the burden on families and society [1].
Walking is a complicated motor pattern [2]. Dynamic standing balance, strength, motor control, and precise movement of the center of pressure are all necessary for normal walking. Most improvements in standing balance and walking ability after the stroke occur within 5 to 8 weeks [3]. However, rehabilitation training (proprioceptive training, gait walking training, lower limb robotic training, and ankle-foot orthosis) can improve gait balance, but the effect of rehabilitation is relatively slow [4]. Therefore, new rehabilitation techniques have become a hot topic of research. Studies have shown that restoring spontaneous neuroplasticity is crucial in gait recovery [5]. Transcranial direct current stimulation (tDCS) is an efficient, simple, portable, safe, and economical noninvasive brain neuromodulation technique [6] that regulates GABAergic and glutamatergic synapses in the cortex by generating low-intensity direct current (usually 1 to 2 mA) through electrodes placed in the cranial area. Synapses, depending on the polarity of the stimulus, cause a change in the depolarization or hyperpolarization of the resting membrane potential of neurons, increasing or decreasing cortical excitability at the anode and cathode, respectively. In addition, it increases cortical blood flow, promotes cortical reorganization, and noninvasively increases neuroplasticity to improve motor skills [7]. Functional magnetic resonance imaging (fMRI) after anodal tDCS stimulation of the M1 area has been shown to significantly increase functional connectivity in the premotor and motor areas of the stimulated hemisphere and modulates the imbalance of connectivity between the left and right hemispheres [8]. Bicephalic tDCS plus functional electrical stimulation improves reaching motor performance after stroke [9].
Rehabilitation of the lower limbs seriously affects daily life. The study of tDCS to improve gait balance disorders in the lower limbs after stroke is an emerging area of research in which treatment with tDCS promotes neurological remodeling on the affected side of the stroke and a certain degree of improvement in gait balance. Still, the stimulation site is seen mainly in the cranially related area where anodal tDCS is placed [10, 11]. One study by Saeys et al. showed a significant improvement in the Tinetti scores compared to the control group in 31 stroke patients after 16 sessions of 1.5 mA, 20 min anodal tDCS [12]. In a chronic stroke patient, Dumont et al. performed 20 min, 2 mA tDCS combined with motor plank training, with anodal tDCS placed in the motor cortex on the side of the lesion, and found that training reduced anterior-posterior sway of the center of gravity (6.18%), displacement trajectory (3.3%), and sway speed (3.3%) [13].
Until now, there are few reports about treating lower limb gait balance disorder with cathodal transcranial direct current stimulation (ctDCS) after stroke [14], primarily seen in rehabilitating upper limb function. A study reported that ctDCS has no beneficial effects on upper motor deficits and quality of life based after stroke compared to sham tDCS. The Fugl-Meyer assessment of motor recovery- (FMA-) upper limb motor, Barthel index (BI), and stroke impact scale (SIS) were assessed before and after treatment [15]. However, in a study of 59 patients divided into a cathodal stimulation group, virtual reality group, and cathodal stimulation combined with the virtual reality training group, the results showed that ctDCS stimulation combined with the virtual reality training group improved upper limb function more significantly than the other two groups [16]. Andrade et al. showed significant improvements in 6MWT and balance BBS indicators in the lower limb of patients after cathodal tDCS stimulation [17], while Fusco et al. did not find improvements in gait-related indicators in their study [18].
TDCS as a noninvasive tool for stroke therapy has shown great potential in the acute phases after cerebral ischemia [19]. A study [20] explored the effects of ctDCS 6 h after focal forelimb M1 ischemia in mice; ctDCS improved motor functionality of the affected forelimbs without changing the ischemic volume. Motor recovery following an ischemic event is correlated with a decrease in the number of microglial cells in the area surrounding the ischemic core; at the same time, microglia morphology shifted toward a healthier state with less phagocytic anti-inflammatory activity.
The initial acute study conducted to mice treated with cathodal tDCS starting after the first 30 minutes of middle cerebral artery occlusion (MCAO) demonstrated that an even earlier intervention using cathodal tDCS led to positive effects on preserving cortical neurons from the ischemic damage, reducing inflammation, and promoting better clinical recovery compared with sham and anodal treatments [21]. These findings suggest a positive role for early ctDCS in neuroprotective effect and motor recovery. However, the effectiveness of ctDCS in poststroke lower limb function is inconclusive; therefore, a large randomized controlled trial is needed to verify its effectiveness. Our paper is aimed at investigating the clinical rehabilitation efficacy of ctDCS on poststroke lower limb motor dysfunction.
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