Combined Transcranial Direct Current Stimulation and Motor Imagery-based Robotic Arm Training for Stroke Rehabilitation

Stroke is the most common cause of adult disability. Current treatments for functional loss of the upper extremity post-stroke remain limited in efficacy, particularly for those with moderate to severe impairment. Previous studies have demonstrated the efficacy of transcranial direct current stimulation (tDCS) for motor recovery post-stroke, a technique of neuromodulation. Motor imagery is effective to enhance motor recovery, with activation of neural pathways similar to that of motor execution. This treatment is accessible to more severely impaired stroke survivors. Our previous studies have demonstrated feasibility and efficacy of motor imagery-based brain computer interface (MI-BCI) for post-stroke motor impairment, in which motor imagery is detected by surface EEG and translated to execution of the target movement with the aid of an arm robot (MIT-Manus). In this study, we investigate the feasibility of combining robot-assisted MI-BCI training, with tDCS to facilitate post-stroke motor recovery in moderate to severe impairment of upper extremity function. We hypothesise that both tDCS-BCI and sham-BCI will improve motor function in the stroke-affected arm; but that tDCS-BCI will be more effective than sham-BCI. Our secondary aim is to gain insight into the neurophysiological mechanism by comparing the cortical excitability changes following sham-BCI vs tDCS-BCI, using transcranial magnetic stimulation (TMS). We will conduct a randomized, double-blinded study with MI-BCI combined with tDCS (tDCS-BCI) vs MI-BCI combined with sham-tDCS (sham tDCS-BCI). Subjects will undergo 10 sessions of tDCS each lasting 20 minutes, followed by 40 minutes of robot-assisted MI-BCI training at each session. Primary outcome will be functional ability measured by upper extremity component of the Fugl-Meyer Assessment. Secondary outcome measures will be the Box \& Block Test, Modified Ashworth Score (measuring spasticity), grip strength and measures of brain activity including tran