Mirror Visual Feedback Prior to Robot-Assisted Training Facilitates Rehabilitation After Stroke: A Randomized Controlled Study

Good luck finding these robotics to go with your mirror therapy.

Embodiment: the representation or expression of something in a tangible or visible form.

Mirror Visual Feedback Prior to Robot-Assisted Training Facilitates Rehabilitation After Stroke: A Randomized Controlled Study

 

Jifeng Rong^1†, Li Ding^2†, Li Xiong¹, Wen Zhang¹, Weining Wang¹, Meikui Deng¹, Yana Wang¹, Zhen Chen^3* and Jie Jia^2,4*

• ¹The Center of Rehabilitation Therapy, The First Rehabilitation Hospital of Shanghai, Shanghai, China
• ²The Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China
• ³The Neurorehabilitation Centre, The First Rehabilitation Hospital of Shanghai, Shanghai, China
• ⁴The National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China

Purpose: Robot-assisted training has been widely used in neurorehabilitation, but its effect on facilitating recovery after stroke remains controversial. One possible reason might be lacking consideration of the role of embodiment in robotic systems. Mirror visual feedback is an ideal method to approach embodiment. Thus, we hypothesized that mirror visual feedback priming with subsequent robot-assisted training might provide additional treatment benefits in rehabilitation.

Method: This is a prospective, assessor-blinded, randomized, controlled study. Forty subacute stroke patients were randomly assigned into an experimental group (N = 20) or a control group (N = 20). They received either mirror visual feedback or sham-mirror visual feedback prior to robot-assisted training for 1.5 h/day, 5 days/week for 4 weeks. Before and after intervention, the Fugl-Meyer Assessment Upper Limb subscale, the Functional Independence Measure, the modified Barthel Index, and grip strength were measured. Scores of four specified games were recorded pre and post one-time mirror visual feedback priming before intervention in the experimental group.

Results: All measurements improved significantly(But to 100% recovery?) in both groups following interventions. Moreover, the Fugl-Meyer Assessment Upper Limb subscale, self-care subscale of the Functional Independence Measure, and the grip strength were improved significantly in the experimental group after a 4-week intervention, compared with the control group. Significantly higher scores of two games were revealed after one-time priming.

Conclusions: Mirror visual feedback prior to robot-assisted training could prompt motor recovery, increase ability of self-care, and potentially enhance grip strength in stroke patients, compared to control treatment. Moreover, mirror visual feedback priming might have the capability to improve the patient's performance and engagement during robot-assisted training, which could prompt the design and development of robotic systems.

Clinical Trial Registration: www.ClinicalTrials.gov, identifier: ChiCTR1900023356.

Introduction

Approximately 75% of stroke patients suffer from upper limb motor impairments, which are challenging and complex to restore (1). Since the first employment in clinical study (2), robot-assisted training (RT), as an intensive and task-specific intervention, has been increasingly used in neurorehabilitation and numerous studies have reported its potential to facilitate upper limb rehabilitation (3–7). Recent studies suggested that repetitions of movement and patient engagement are determinants in neural plasticity, which is of great importance for prompting rehabilitation (8, 9). With engagement increasing, patient–robot interaction, which plays a critical role in robotic systems, could be enhanced (10). Moreover, patients with strong motivation could pay more attention and could actively attempt to accomplish physical exercise during RT. Therefore, approaches and strategies, such as virtual reality (VR) and assist-as-needed, have been proposed to increase patient participation and motivation in RT (11). However, to the best of our knowledge, there are few methods and research focusing on reinforcing patient engagement or attention from the perspective of embodiment prior to RT.

Embodiment, also called bodily self-consciousness, is a kind of experience, which comprise four basic components, namely, body ownership, location, agency, and deafference (12, 13). Illusions stemming from rubber hand, mirror visual feedback (MVF), and VR have been suggested to evaluate aspects of embodiment (14–17). Research on stroke rehabilitation demonstrate that the experience of embodiment during these visual stimulations, like MVF, has the potential to alter the patient's sensorimotor activity and contribute to motor recovery (18–20). Studies reported that MVF priming had an instant effect on neural modulation and a long-term effect on neural plasticity, which was recognized as the underlying therapeutic mechanism (20–23). Moreover, patients with hemiparalysis after stroke may obtain more benefits on motor function restoration through the substitution of paralyzed limbs with visual inputs of the active side controlled by the patients themselves (24, 25). Wainer et al. reported that embodiment could affect patients' engagement and presented a positive correlation between the embodiment perception and the effectiveness of RT (26). Thus, we inferred that lacking education or perception of embodiment might limit the benefits achieved from RT in patients with stroke. Additionally, our previous studies demonstrated that the embodiment deriving from MVF could enhance the patient's attention to affected upper limb, which might strengthen the control of paralyzed limbs and hinder the development of learned non-use after stroke (18, 27). Therefore, we hypothesized that using MVF as a priming technique to promote the patient's attention to affected limbs and train the embodiment perception prior to RT might facilitate the rehabilitation process after stroke.

In the present study, an arm rehabilitation robot and a customized camera-based MVF (camMVF) (18, 27) were employed to provide robot-assisted upper limb training and MVF for patients after stroke. A randomized controlled study was designed to investigate the potential effects of MVF prior to RT on motor function, daily activities, grip strength, and gamified training performance.

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