Robot and tDCS Based Proprioceptive Rehabilitation After Stroke

Background and Rationale: Proprioception is the awareness of where our limbs are in space, in the absence of vision. It is an important sense that allows us to have control over our movement and perform many activities of daily living. Every year, approximately 62,000 Canadians suffer from a stroke. Around 50% of individuals who suffer from a stroke are left with deficits in proprioception, yet clinically very little is done to rehabilitate this sense. Two novel interventions for rehabilitating proprioception are robotic rehabilitation and Transcranial Direct Current Stimulation (tDCS). Robotic rehabilitation is potentially beneficial over conventional therapies as the number of repetitions performed in a single session can be drastically increased and these movements can be performed in a well-controlled manner, something that is more difficult in conventional therapy. It is also easy to occlude vision when performing rehabilitation in a robotic environment, meaning proprioceptive retraining can be explicitly targeted. tDCS is another technology which has the potential to enhance rehabilitation. The technique involves placing two sponge electrodes over the scalp and passing a small electrical current (1-2mA) between the two electrodes, altering the membrane potential of the brain tissue through which the current passes. When tDCS has been paired with training, it has been shown to enhance learning in both healthy and stroke populations. tDCS has yet to be investigated to improve proprioception in a stroke population.

Research Question: Can a combination of robotic rehabilitation and tDCS enhance proprioception in a chronic stroke population?

Ethics: This study has been approved by the Research Ethics Board at the University of Calgary

Design: This is a Single-Blinded, Pilot, Randomized Controlled Trial with a Sham Arm

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Recruitment: 30 individuals with proprioceptive deficits beyond 6-months post-stroke are being recruited from the outpatient stroke community in Calgary, Alberta, Canada.

Randomization: Individuals are randomized into one of three groups: robotic rehabilitation plus anodal tDCS, robotic rehabilitation plus sham tDCS or standard of care rehabilitation.

Robotic Intervention: The robotic rehabilitation intervention consists of 10-days of robotic therapy in the Kinesiological Instrument for Normal and Altered Reaching Movements (KINARM) Exoskeleton. Robotic rehabilitation is conducted for 1 hour each day, on 10 consecutive days (excluding weekends). Therapy is tailored specifically towards rehabilitating proprioception and consists of a battery of 5 simple video game-like tasks. Each task is performed for 10-15 minutes each day. The order in which these tasks are completed are pseudo-randomized each day. Each day a motivation questionnaire will be completed.

tDCS Intervention: In addition to robotic rehabilitation, those in the tDCS group will also receive 20 minutes of 2mA anodal tDCS. This is applied during the first 20 minutes of each robotic session and is targeted over the ipsilesional sensory cortex. For the sham condition, the same setup will be used. Each day a tDCS tolerability questionnaire will be completed.

Assessments: All subjects will undergo 3 robotic assessments of proprioceptive performance, one at baseline (day 1), one immediately after the intervention (day 12) and one more at 3 months follow up. Two components of proprioception will be assessed during these robotic assessments (position sense and movement sense). Robotic assessments will be conducted in the same robotic exoskeleton that the therapy is delivered in.

A variety of clinical scales (Fugl-Meyer Assessment, Functional Independence Measure, and Nottingham Sensory Scale) will be collected at each time point. These will be secondary outcome measures. Performance on a robotic assessment of visually-guided reaching will also be a secondary outcome measure. All clinical assessments will be performed by a blinded assessor therapist.

Data analysis: Primary outcome measures will be analysed using a repeated measures ANOVA. Comparisons will be made between groups at each assessment time points. Secondary outcome measures and questionnaire data will also be analysed with a repeated measures ANOVA.