Research Report
Population: Adult
Kathryn S Hayward, PT PhD, Postdoctoral Fellow, University of Queensland; James Cook University k.hayward@uq.edu.au
Richard Carson, PhD, Professor, Trinity College; Queens University Richard.Carson@tcd.ie
Kathy Ruddy, PhD, Postdoctoral Fellow, Swiss Federal Institute of Technology kathy.ruddy@hest.ethz.ch
Sandra Brauer, PT PhD, Professor, University of Queensland s.brauer@uq.edu.au
Ruth Barker, PT PhD, Clinical Leader & Adjunct Senior Lecturer, James Cook University; Northern Australia Primary Health ruth.barker@jcu.edu.au
Keywords: Participation, Stroke, Upper Extremity, Task-Oriented Training
Purpose: Reaching training can promote recovery of function in stroke survivors with severe arm paresis. To amplify cortical activity and enhance functional benefits, training has been combined with non-invasive brain stimulation (e.g., transcranial-direct current stimulation), but with limited success in people with severe paresis. An alternative approach is transcranial random noise stimulation (tRNS). Here, it is thought that by adding random noise, the detection of weak stimuli (or the information content of a signal) will be enhanced and thus, boost the adaptive potential of the stimulated cortical area. The aim of this study was to investigate the feasibility of combining reaching training with tRNS timed to coincide with the generation of a voluntary motor command in stroke survivors with chronic and severe arm paresis.
Subjects: Four stroke survivors 6-months to 5-years post stroke with severe arm paresis (triceps manual muscle test ≥2-; Motor Assessment Scale Item 6 [MAS6] ≤3 out of 6) who were not currently taking any medications that had the potential to alter cortical excitability e.g., antidepressants and had no contraindications to tRNS or MRI.
Methods: A triple-blind pilot RCT was completed. Participants were randomly allocated to 12 sessions of reaching training over 4-weeks with active or sham tRNS delivered over C3/C4. tRNS delivery was triggered by a ‘go’ signal so as to coincide stimulation with a voluntary movement attempt, which ceased after 5-seconds. At this point, outcome-triggered electrical stimulation could be delivered to triceps brachii to enable full range reaching. To determine feasibility we considered: 1) ability to complete repetitive training, 2) potential to improve on clinical outcomes between time-points (pre-, post-training, follow-up) and 3) adverse events. To determine if the ability to engage in training was contingent upon the structural integrity of descending white matter projections, diffusion weighted imaging of the posterior limb of the internal capsule (PLIC) was undertaken. The asymmetry index (AI) between lesioned and non-lesioned hemisphere PLIC projections was calculated, with an AI >0.15 classified as loss beyond the point of no return (PNR).
Results: Two participants received active and two sham tRNS. Two participants had no extractable PLIC tracts in the lesioned hemisphere (n = 1 active and n = 1 sham tRNS). All participants completed all training sessions, engaged in repetitive practice (1763, 1128, 1015, 1696 total repetitions respectively) and demonstrated clinical improvements across functional outcomes including triceps muscle strength, MAS6 and REACH scale. However, outcomes demonstrated were individualised and appeared irrespective of tRNS group and PNR classification. There were no adverse events.
Conclusion: Reaching training that includes tRNS timed to coincide with the generation of voluntary motor commands is feasible.
Clinical relevance: People with severe paresis can engage in repetitive task-oriented reaching practice and achieve clinical improvements, even when AI is classified as beyond the PNR.
Citation:
Hayward, Kathryn S, PT PhD; Carson, Richard G, PhD; Ruddy, Kathy L, PhD; Brauer, Sandra G, PT PhD; Barker, Ruth N, PT PhD. Repetitive reaching training combined with transcranial Random Noise Stimulation in stroke survivors with chronic and severe arm paresis: A triple blind pilot RCT.. Poster Presentation. IV STEP Conference, American Physical Therapy Association, Columbus, OH, July 17, 2016. Online. https://u.osu.edu/ivstep/poster/abstracts/010_hayward-et-al/