Evidence of neuroplasticity with robotic hand exoskeleton for post-stroke rehabilitation: a randomized controlled trial

Abstract

Background: A novel electromechanical robotic-exoskeleton was designed in-house for the rehabilitation of wrist joint and Metacarpophalangeal (MCP) joint.

Objective: The objective was to compare the rehabilitation effectiveness (clinical-scales and neurophysiological-measures) of robotic-therapy training sessions with dose-matched conventional therapy in patients with stroke.

Methods: A pilot prospective parallel randomized controlled study at clinical settings was designed for patients with stroke within 2 years of chronicity. Patients were randomly assigned to receive an intervention of 20 sessions of 45 min each, five days a week for four weeks, in Robotic-therapy Group (RG) (n = 12) and conventional upper-limb rehabilitation in Control-Group (CG) (n = 11). We intended to evaluate the effects of a novel exoskeleton based therapy on the functional rehabilitation outcomes of upper-limb and cortical-excitability in patients with stroke as compared to the conventional-rehabilitation. Clinical-scales- Modified Ashworth Scale, Active Range of Motion, Barthel-Index, Brunnstrom-stage and Fugl-Meyer (FM) scale and neurophysiological measures of cortical-excitability (using Transcranial Magnetic Stimulation) -Motor Evoked Potential and Resting Motor threshold, were acquired pre- and post-therapy.

Results: No side effects were noticed in any of the patients. Both RG and CG showed significant (p < 0.05) improvement in all clinical motor-outcomes except Modified Ashworth Scale in CG. RG showed significantly (p < 0.05) higher improvement over CG in Modified Ashworth Scale, Active Range of Motion and Fugl-Meyer scale and FM Wrist-/Hand component. An increase in cortical-excitability in ipsilesional-hemisphere was found to be statistically significant (p < 0.05) in RG over CG, as indexed by a decrease in Resting Motor Threshold and increase in the amplitude of Motor Evoked Potential. No significant changes were shown by the contralesional-hemisphere. Interhemispheric RMT-asymmetry evidenced significant (p < 0.05) changes in RG over CG indicating increased cortical-excitability in ipsilesional-hemisphere along with interhemispheric changes.

Conclusion: Robotic-exoskeleton training showed improvement in motor outcomes and cortical-excitability in patients with stroke. Neurophysiological changes in RG could most likely be a consequence of plastic reorganization and use-dependent plasticity. Trial registry number: ISRCTN95291802.

Keywords: Cortical-excitability; Metacarpophalangeal joint; Neurological rehabilitation; Robotic exoskeleton; Stroke; Transcranial Magnetic Stimulation; Wrist.

Fig. 1

Patient Enrolment Consort

Fig. 2

Whole set-up of exoskeleton with performance biofeedback, voluntary cue and PCB in the black control box which also works as user interface [28]

Fig. 3

a Scatter-plot showing the relationship between improvements in RMT in the ipsilesional-hemisphere and improvements in functional performance of the distal-component pre-to-post-therapy for individual patient’s data. Greater decreases in motor-threshold tend to show greater increases in FMW/H. Red Line (RG) and the blue line (CG) represents a linear-trend in improvement in distal motor-outcome (∆FMW/H) score as a function of change in the ipsilesional-hemisphere (∆RMTipsi) in RG and CG pre-to-post-therapy in which RG shows a significant correlation (r = 0.64, F = 7.24, p = 0.022), b Scatter-plot showing the relationship between change in RMT asymmetry-ratio (ipsilesional/contralesional) pre-to-post-therapy and functional performance of distal-component for individual patient’s data. Greater decreases in motor-threshold tend to show greater increases in FMW/H. The red line (RG) and the blue line (CG) represents a linear-trend in improvement in distal motor-outcome (∆FMW/H) score as a function of change in RMT-ratio (∆RMTasymm-ratio) in RG and CG pre-to-post-therapy in which RG shows a significant correlation (r = 0.6, F = 5.77, p = 0.03)