A Robotic System with EMG-Triggered Functional Electrical Stimulation for Restoring Arm Functions in Stroke Survivors. 

The goal of this study is to conduct an adequately sized randomised controlled trial to evaluate the efficacy of robotic training combined with FES compared to advanced conventional therapy. The paper begins by stating that task oriented, high intensity and patients’ active participation facilitate cortical reorganisation.  

The authors report review article from literature which claim robot assisted training improves ADL (Cochrane review) and few others that had no effect on ADL (RATULS and review with 44 RCTs). They state that there is a need to advance towards robot-assisted personalized, task-oriented and ADL training. The paper then talks about FES, which has started 20 years ago and is recommended for patients with minimum movement. They report studies that showed FES provides higher improvement in body function and structure and activity domain and FES synchronised with volitional EMG enhances neuroplasticity.  Following this they also report studies that showed higher motor outcomes when robotic training is integrated with FES and voluntary effort. The authors claims that such hybrid robotic system makes the robotic training more functionally oriented. Therefore, the objective of the paper was to evaluate if hybrid robotic systems (arm training supported by RETRAINER integrated with EMG triggered FES) with task-oriented training improves arm function, strength, dexterity, and quality of life.  

Methods  

The study was single blinded RCT conducted in two centres. (The patient were recruited for a pilot study between 2016-2018 and the same patients were included in the analysis from 2017..)  

First time stroke between with time since stroke between 2 weeks up to 9 months were recruited with low level of spasticity (MAS < 2) and (MIC < 80) unaffected side. Patients were excluded if they had inability to tolerate FES and had major visual deficits.  

Intervention:   

• Participants were randomly assigned to advance conventional therapy group (control group) and RETRAINER group (experimental group).  

• Training duration for both groups: 90 minutes, 3 times/ week for 9 weeks. 

• The experimental group had 30 minutes of training with RETRAINER + 60 minutes of ACT 

• Control group had 90 minutes of ACT. 

• ACT was tailored for each patient (upper limb passive or active motion, arm cycle ergometer without FES, FES of forearm, virtual reality, repetitive arm training, mirror therapy.) 

• RETRAINER was 4 DOF passive exoskeleton equipped with electromagnetic brakes to provide antigravity support.  

• The exoskeleton was integrated with FES system, which was provided up to 2 arm muscles. 

• Biphasic (25 hz and 300

• μs

• 𝜇�

• ) pulse with increasing amplitude was triggered when the volitional EMG crossed threshold. 

• Visual feedback about the active participation was provided when FES was active (happy/sad emoji: active/passive). 

• Interactive objects with RFID and angle sensors to monitor positions were used. 

Outcome measure: 

• Primary outcome: ARAT 

• Secondary outcome: Motricity index, MAL, BBT, stroke specific quality of life scale (SSQoL), SUS, Technology acceptance model (TAM).    

Results 

• At baseline:  significant difference in age (exp group 7 years less than the control group) 

• FES forearm and repetitive task training, hand to mouth and anterior reaching on plane were most chosen ACT training and RETRAINER exercise respectively.  

• All outcomes except SSQol showed significant time effect. 

• Significant interaction effect: ARAT, BBT 

• Between group change of 11.5 at T1 and 13.6 at T2 in favour of experimental group was observed (More the MIC of 12 points at T2). 

• Percentage of clinically improved patients were not significantly different at T1 (47% RETRAINER and 28% ACT). But were significantly different at T2 (58% and 29 % exp & control group respectively). Subgroup analysis showed similar results with elderly and early subacute patients. 

• Significant differences were seen between groups with left hemispheric patients but not with right hemispheric patients. 

• High compliance, moderately usable (SUS: 61.5 +/- 22.8), useful and easy to use (TAM : 76%)  

Discussion 

• The experimental group higher improvements in arm functions, the authors report the following advantages of RETRAINER:  

• Personalised and task-oriented training. 

• High intensity active training (12 minutes / 30 minutes) 

• Enhanced sensory inputs.  

• “almost” physiological motor experience 

• Length of training (9 weeks) longer than other RCTs. 

• Unlike RATULS, RETRAINER group showed significant improvement in activity domain along with body functions structure domain, as RETRAINER feature are well grounded on neurophysiological basis. 

• Higher improvement in arm function did not translate to improvement in performing ADL, the possible reason there is no support for hand functions, they suggest to add arm and hand module of RETRAINER. 

• From the results of the Subgroup Analysis 

• Early intervention is beneficial. 

• Technology familiarization does not influence RETRAINER induced benefits in elderly. 

• Left hemiparetic are affected by perception disturbance, RETRAINER explore peri personal space thus increased effect. 

• Limitation of the study were:  

• Unmatched age at baseline 

• Time since stroke quite broad 

• Length of treatment – need for home-based devices. 

• Short follow up period 

• Perceptive disorder was not assessed. 

• Dominant side not noted.