Enhancing Recovery of Arm Movement in Stroke Patients

Training approaches based on established principles of motor learning and neural plasticity and non-invasive brain stimulation such as repetitive Transcranial Magnetic Stimulation and transcranial Direct Current Stimulation (tDCS) show promise in modulating brain activity in order to enhance upper limb (UL) motor recovery. However, the potential for recovery may still not be attained if training programs do not specifically focus on remediating motor impairment as defined by motor control science. This project is driven by a major theory of motor control (Threshold Control Theory) suggesting that rather than directly specifying motor commands to muscles, descending systems regulate spatial thresholds (STs) of reflexes to generate and control voluntary movement within specific areas of joint space. In patients with stroke, ST control is diminished leading to the appearance of muscle spasticity, weakness and abnormal muscle activation patterns during voluntary movement within well-defined spatial (angular) zones. The investigators hypothesize that recovery of voluntary motor control is tightly linked to the recovery of threshold control. The investigators propose a training program that incorporates personalized tDCS to balance cortical hypo/hyperexcitability as well as personalized movement arm reaching training based on the identification of disorders in ST.

Overall objectives of the proposal are:

• To test the effectiveness of personalized training programs to increase the range of regulation of STs in the elbow during reaching.
• To determine the effects of repetitive tDCS aimed at inhibiting excessive/exciting diminished cortical activity.
• To determine the feasibility of implementing personalized training programs in high and low-to-middle income countries.

Sixty patients with sub-acute (3 wks-6 mos) stroke will be recruited in this multi-site international trial taking place in Canada, Israel and India. Participants will have spasticity in the elbow flexors and/or extensors, with some active elbow control. Each site will recruit and randomize patients into one of 3 treatment groups. Group 1 will receive tDCS and practice personalized arm motor training. Group 2 will also receive tDCS with non-specific practice. Group 3 will receive Sham-tDCS and personalized practice. Training will consist of the application of tDCS in the first 30 minutes of a 50-minute arm reaching practice session,, 5 days per week for 2 weeks. Primary outcome measures (Pre, Post, Follow-up) are elbow flexor and extensor STs and related spasticity/active control zones. Secondary measures are clinical measures of UL motor activity. By accounting for the spatial structure of motor deficits, our research will benefit both researchers and clinicians by advancing our understanding of the mechanisms underlying unimpaired/impaired motor control and recovery.

Inclusion criteria

• first ever cortical or cortical/subcortical stroke confirmed by MRI/CT and medically stable;
• sub-acute stage of stroke (3 wk to 6 mo post-stroke);
• arm paresis (Chedoke-McMaster Arm Scale of 2-6 /7; Gowland et al. 1993) but able to perform voluntary elbow flexion/extension of at least 30° per direction;
• elbow flexor and/or extensor spasticity (> 1+/4 on Modified Ashworth Scale; Ashworth 1964; Bohannon and Smith 1987);
• able to provide informed consent.

Exclusion criteria

• major neurological (other than stroke) / neuromuscular / orthopaedic problems or pain that may interfere with interpretation of results;
• major cognitive deficits (a score <20 on the Montreal Cognitive Assessment, Nasreddine et al. 2005);
• history of psychiatric disorders, alcohol or drug abuse, skin sensitivity, seizures, migraines, metal in cranium and other implants (cochlear, cardiac);
• taking medications (e.g. epileptic and psychoactive drugs) that could affect brain activity (Poreisz 2007).