Reward During Arm Training Improves Impairment and Activity After Stroke: A Randomized Controlled Trial

 If you create 100% recovery protocols, the reward of recovery will be enough to get the therapy done,even if it requires 10 million repetitions. Use the correct reward structure and you'll get 100% compliance. This was not properly thought through.

Reward During Arm Training Improves Impairment and Activity After Stroke: A Randomized Controlled Trial

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Mario Widmer, Jeremia P. O. Held, Frieder Wittmann, ...

First Published December 22, 2021 Research Article 

https://doi.org/10.1177/15459683211062898

Article information

Abstract

Background

Learning and learning-related neuroplasticity in motor cortex are potential mechanisms mediating recovery of movement abilities after stroke. These mechanisms depend on dopaminergic projections from midbrain that may encode reward information. Likewise, therapist experience confirms the role of feedback/reward for training efficacy after stroke.

Objective

To test the hypothesis that rehabilitative training can be enhanced by adding performance feedback and monetary rewards.

Methods

This multicentric, assessor-blinded, randomized controlled trial used the ArmeoSenso virtual reality rehabilitation system to train 37 first-ever subacute stroke patients in arm-reaching to moving targets. The rewarded group (n = 19) trained with performance feedback (gameplay) and contingent monetary reward. The control group (n = 18) used the same system without monetary reward and with graphically minimized performance feedback. Primary outcome was the change in the two-dimensional reaching space until the end of the intervention period. Secondary clinical assessments were performed at baseline, after 3 weeks of training (15 1-hour sessions), and at 3 month follow-up. Duration and intensity of the interventions as well as concomitant therapy were comparable between groups.

Results

The two-dimensional reaching space showed an overall improvement but no difference between groups. The rewarded group, however, showed significantly greater improvements from baseline in secondary outcomes assessing arm activity (Box and Block Test at post-training: 6.03±2.95, P = .046 and 3 months: 9.66±3.11, P = .003; Wolf Motor Function Test [Score] at 3 months: .63±.22, P = .007) and arm impairment (Fugl-Meyer Upper Extremity at 3 months: 8.22±3.11, P = .011).

Conclusions

Although neutral in its primary outcome, the trial signals a potential facilitating effect of reward on training-mediated improvement of arm paresis.

Trial registration

ClinicalTrials.gov (ID: NCT02257125).

Keywords

rehabilitation, stroke, upper extremity, virtual reality, feedback, reward

Introduction

After stroke, 50% of survivors are left with upper extremity impairments,^1,2 a disability that lowers their health-related quality of life.³ Therapies to cure or ameliorate arm impairment are limited in their population efficacy, although some patients respond to therapy or recover spontaneously. Apart from training dose (ie, time spent training), it is unknown what makes training effective and in whom. When training dose is matched, most randomized controlled trials introducing new interventions (eg, robot-assisted therapy)⁴ showed no difference to control being routine care or conventional physical/occupational therapy. Assuming that currently available therapies do not fully exploit the biological recovery potential,⁵ there is urgent need for improvement.

Improvement may be achieved by identifying effective elements of therapy and boosting them. Reward during training may be one such element. In the rat, dopaminergic projections from the midbrain’s ventral tegmental area (VTA) to primary motor cortex (M1) are necessary for successful motor skill learning.⁶ Dopamine in M1 modulates excitability⁷ and enables long-term potentiation of cortico-cortical connections.⁸ Populations of dopaminergic VTA neurons respond to food rewards as well as to the combination of reward and training.⁹ In humans, reward enhances procedural¹⁰ and motor skill learning^11,12 and has a positive effect on motor adaptation.¹³ This is mainly the result of improved retention or consolidation.^11–13 In a functional magnetic resonance imaging study, we demonstrated that adding monetary rewards after good performance leads to better consolidation and higher ventral striatum activation than knowledge of performance alone,¹² the striatum being a key area of reward processing.^14,15

While motor skill learning is not the only mechanism mediating movement recovery after stroke, it certainly is an important factor.^16,17 It therefore seems likely that reward will also affect recovery, as it does skill learning. We thus hypothesized that augmenting reward improves recovery in response to training. Using the ArmeoSenso, a standardized virtual reality-based training system, allowed for delivery of intensive repetitive training of the upper limb¹⁸ while rewarding features like game scores (linked to a monetary reward), visual and sound special effects of the applied therapy game could be easily manipulated. Here we report a proof-of-concept, assessor-blinded, multicenter randomized controlled trial comparing the effect of enhanced feedback and reward vs unrewarded training matched in time and movement repetitions on arm activity and impairment.