Abstract
BackgroundA significant proportion of individuals are left with poor residual functioning of the affected arm after a stroke. This has a great impact on the quality of life and the ability for stroke survivors to live independently. While strengthening exercises have been recommended to improve arm function, their benefits are generally far from optimal due to the lack of appropriate dosing in terms of intensity. One way to address this problem is to develop better tools that could predict an individual’s potential for recovery and then adjust the intensity of exercise accordingly. In this study, we aim at determining whether an individualized strengthening program based on the integrity of the corticospinal tract, as reflected in the amplitude of motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS), in conjunction with transcranial direct current stimulation (tDCS), could lead to more optimal outcomes in terms of arm function in chronic stroke patients.MethodsThis multicentre, double-blinded, randomised controlled trial will aim to recruit 84 chronic stroke patients. Before and after training, participants will undergo a clinical evaluation, assessing motor recovery of the affected arm (Fugl-Meyer Stroke Assessment-FMA) and a TMS evaluation to assess the integrity of the corticospinal tract, as reflected in MEP amplitude. Based on their baseline MEPs amplitude, participants will be stratified into three groups of training intensity levels determined by the one-repetition maximum (1RM); 1) low: 35–50% 1 RM (MEPs < 50 μV); 2) moderate: 50–65% 1RM (MEPs 50-120 μV); and 3) high: 70–80% 1RM (MEPs > 120 μV). Training will target the affected arm (3 times/week for 4 weeks). In addition, participants will be randomly allocated into two tDCS groups (real vs. sham) and tDCS will be applied in an anodal montage during the exercise.DiscussionThis study will determine whether an individualized strength training intervention in chronic stroke survivors can lead to improved arm function. In addition, we will also determine whether combining anodal tDCS over the lesioned hemisphere with strength training can lead to further improvement in arm function, when compared to sham tDCS.Trial registrationClinicalTrials.gov Identifier: NCT02915185. Registered September 21 2016.
Highlights
A significant proportion of individuals are left with poor residual functioning of the affected arm after a stroke
A meta-analysis by Coupar et al [13] found that neurophysiological factors, such as the integrity of the corticospinal tract assessed by non-invasive brain stimulation (NIBS) techniques, were strongly associated with upper limb recovery after a stroke; supporting the use of neurophysiological markers in determining a person’s potential for recovery and functional performance
Results from a meta-analysis [35] support the therapeutic potential of transcranial direct current stimulation (tDCS) as an adjuvant treatment strategy to enhance training in stroke patients with upper limb deficits, where tDCS demonstrated a significant impact on rehabilitative training with a moderate effect size of + 0.52 (p < 0.001) and + 0.69 (p < 0.001) for both immediate and longer-lasting analyses, respectively
Summary
Study design and setting This is a multi-centre, randomised controlled trial (RCT) study. As intensity plays a crucial role in response to training, the intensity of the strength training program will be tailored to each participant’s potential for recovery based on their baseline MEP amplitudes and gradation of the intensity will follow the ASA recommendation [47] and will be based on the 1RM This same gradation will be applied for the hand muscles based on the participants’ maximal grip force on the JAMAR®. Preliminary results based on this study showed a 7-point gain on the FMA scale after 4 weeks of strength training for participants presenting pre-training MEPs. we estimate that the tDCS sham group (including participants with and without MEP) will show at least a 6-point gain on the FMA scale, exceeding the 5-point gain minimal detectable change (MDC) of this scale [57]. If an interaction is noted, paired t-tests will be used to locate any significant differences in each stratum with a Bonferroni correction for multiple tests (adjusted p-value of 0.02)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
