[Paper Review] A wearable anti-gravity supplement to therapy does not improve arm function in chronic stroke: a randomized trial

Courtney Celian, Partha Ryali+3 more|arXiv (Cornell University)|May 7, 2024

Stroke Rehabilitation and RecoveryMedicine3 citations

TL;DR

This randomized trial evaluated the ExoNET wearable anti-gravity device as a supplement to occupational therapy in chronic stroke survivors. Although the device was safe and feasible, and showed a significant improvement in Box and Blocks scores (effect size: 2.1, p = .04), no significant differences were found between groups in ARAT scores or other primary clinical metrics, suggesting limited overall efficacy for arm function recovery.

ABSTRACT

Background: Gravity confounds arm movement ability in post-stroke hemiparesis. Reducing its influence allows effective practice leading to recovery. Yet, there is a scarcity of wearable devices suitable for personalized use across diverse therapeutic activities in the clinic. Objective: In this study, we investigated the safety, feasibility, and efficacy of anti-gravity therapy using the ExoNET device in post-stroke participants. Methods: Twenty chronic stroke survivors underwent six, 45-minute occupational therapy sessions while wearing the ExoNET, randomized into either the treatment (ExoNET tuned to gravity-support) or control group (ExoNET tuned to slack condition). Clinical outcomes were evaluated by a blinded-rater at baseline, post, and six-week follow-up sessions. Kinetic, kinematic, and patient experience outcomes were also assessed. Results: Mixed-effect models showed a significant improvement in Box and Blocks scores in the post-intervention session for the treatment group (effect size: 2.1, p = .04). No significant effects were found between the treatment and control groups for ARAT scores and other clinical metrics. Direct kinetic effects revealed a significant reduction in muscle activity during free exploration with an effect size of (-7.12%, p< 005). There were no significant longitudinal kinetic or kinematic trends. Subject feedback suggested a generally positive perception of the anti-gravity therapy. Conclusions: Anti-gravity therapy with the ExoNET is a safe and feasible treatment for post-stroke rehabilitation. The device provided anti-gravity forces, did not encumber range of motion, and clinical metrics of anti-gravity therapy demonstrated improvements in gross manual dexterity. Further research is required to explore potential benefits in broader clinical metrics.

Motivation & Objective

• To assess the safety and feasibility of wearable anti-gravity therapy using the ExoNET device in chronic stroke survivors.
• To evaluate whether anti-gravity assistance during occupational therapy improves upper limb function in chronic stroke.
• To compare clinical, kinetic, and kinematic outcomes between participants using gravity-support mode versus slack condition.
• To examine patient-reported experiences and perceptions of the anti-gravity therapy device.

Proposed method

• Twenty chronic stroke survivors were randomized into treatment (ExoNET tuned to gravity-support) or control (ExoNET in slack condition) groups.
• Participants completed six 45-minute occupational therapy sessions over a 3-week period.
• Clinical outcomes were measured using standardized assessments including the Box and Blocks Test and the Action Research Arm Test (ARAT), evaluated by a blinded rater at baseline, post-intervention, and 6-week follow-up.
• Kinetic and kinematic data were collected during free exploration tasks to assess muscle activity and movement patterns.
• Subject feedback was collected to evaluate user experience and perception of the device.
• Mixed-effects models were used to analyze longitudinal changes in clinical and physiological outcomes.

Experimental results

Research questions

• RQ1 Does wearable anti-gravity therapy with the ExoNET device lead to significant improvements in upper limb function in chronic stroke survivors compared to standard therapy?
• RQ2 Is the ExoNET device safe and feasible for use during occupational therapy in a clinical setting?
• RQ3 Are there measurable changes in muscle activity or movement kinematics during anti-gravity assistance?
• RQ4 Does patient perception of the device correlate with clinical or kinetic improvements?
• RQ5 Are there sustained benefits in arm function at 6-week follow-up after the intervention ends?

Key findings

• The treatment group showed a statistically significant improvement in Box and Blocks scores (effect size: 2.1, p = .04) post-intervention.
• No significant between-group differences were observed in ARAT scores or other primary clinical metrics.
• A significant reduction in muscle activity was observed during free exploration in the treatment group (effect size: -7.12%, p < .005).
• No significant longitudinal trends were found in kinetic or kinematic data across the study period.
• Participants reported generally positive perceptions of the anti-gravity therapy and the device's usability.
• The ExoNET device provided effective anti-gravity assistance without restricting range of motion, supporting its feasibility for clinical use.