Changes in Trunk Compensation and Reaching Performance as a Result of a Novel Virtual Reality–Based Intervention for People With Chronic Stroke

BACKGROUND AND PURPOSE: The recruitment of excessive trunk flexion during reaching movements is one of the most common and well-researched poststroke compensation strategies for people with hemiparesis (Cirstea & Levin, 2000). The continued use of the trunk to adapt to limitations in functional tasks and activity performance may lead to chronic pain and suboptimal motor recovery in the impaired upper extremity (Levin et al., 2009). Virtual reality (VR) is a novel rehabilitation tool that is able to motivate clients to complete large numbers of task-based repetitions intended to drive neuroplastic change and motor recovery (Laver et al., 2015). VR may also be able to provide feedback during repetitive practice to incrementally shape the use of trunk compensation during impaired reaching. The purpose of this study was to determine the preliminary efficacy of a custom-designed VR tool for reducing trunk compensation and improving reaching performance when implemented within a VR-based motor intervention for people with chronic hemiparetic stroke.

METHOD: A small cohort (N = 5) of people with chronic stroke took part in an 18-session intervention over the course of 6 wk (3×/wk, 1 hr/session). Participants were aged 44–78, were ≥6 mo poststroke, had mild to moderate impairment (National Institutes of Health Stroke Scale arm/motor scores of 1–3), and exhibited ≥20° of compensatory trunk flexion during a simple reaching task.

The VR tool used for this study was designed to use the Kinect v2 (Microsoft, Redmond, WA) custom control software and online videogames to convert upper extremity movement into virtual events and the automatic provision of compensation-related feedback. During each session and after a calibration procedure, participants interacted with four different videogames of their choosing by repeatedly reaching to a virtual target situated at their maximal range of motion (ROM). Real-time feedback was provided relative to a 90% threshold of their calibrated trunk compensation maximum in the form of a red stoplight signal, a loud buzzer sound, and cancellation of the virtual event. In this way, both reaching performance and trunk compensation were effectively shaped and challenged during each intervention session.

A standardized reach test (Wagner et al., 2008) involving multiple extended reaches to a single target in the scaption plane was completed pre- and postintervention to assess changes in reaching performance. An eight-camera video motion capture system was used to measure kinematic variables including reaching ROM, shoulder flexion and abduction, trunk flexion and lateral flexion, and elbow flexion. Pre- to postintervention changes were analyzed using Wilcoxon’s signed rank test (α = .05) and Spearman rank correlation coefficients.

RESULTS: Compensatory trunk flexion during extended reaching decreased significantly from pre- to postintervention (M = –8.2°, p = .04). Sagittal plane reaching ROM (M = 4.8 cm, p = .04), frontal plane reaching ROM (M = 3.9 cm, p = .04), and shoulder abduction (M = 3.1°, p = .04) increased significantly. Correlations between performance improvements and compensation reductions were small and not statistically significant (–.20 < ρ < .40).

CONCLUSION: The VR tool designed and implemented as an intervention in this study reduced trunk compensation and improved reaching performance in a small cohort of people with stroke. Future work should focus on further improvements to the system software and the application of this therapy tool within a larger, controlled study to establish its clinical efficacy.

References

Cirstea, M. C., & Levin, M. F. (2000). Compensatory strategies for reaching in stroke. Brain, 123, 940–953. https://doi.org/10.1093/brain/123.5.940

Laver, K. E., George, S., Thomas, S., Deutsch, J. E., & Crotty, M. (2015). Virtual reality for stroke rehabilitation. Cochrane Database of Systematic Reviews, 2015, CD008349. https://doi.org/10.1002/14651858.CD008349.pub3

Levin, M. F., Kleim, J. A., & Wolf, S. L. (2009). What do motor “recovery” and “compensation” mean in patients following stroke? Neurorehabilitation and Neural Repair, 23, 313–319. https://doi.org/10.1177/1545968308328727

Wagner, J. M., Rhodes, J. A., & Patten, C. (2008). Reproducibility and minimal detectable change of three-dimensional kinematic analysis of reaching tasks in people with hemiparesis after stroke. Physical Therapy, 88, 652–663. https://doi.org/10.2522/ptj.20070255