Effectiveness of unilateral lower-limb exoskeleton robot on balance and gait recovery and neuroplasticity in patients with subacute stroke: a randomized controlled trial

Abstract

Background: Impaired balance and gait in stroke survivors are associated with decreased functional independence. This study aimed to evaluate the effectiveness of unilateral lower-limb exoskeleton robot-assisted overground gait training compared with conventional treatment and to explore the relationship between neuroplastic changes and motor function recovery in subacute stroke patients.

Methods: In this randomized, single-blind clinical trial, 40 patients with subacute stroke were recruited and randomly assigned to either a robot-assisted training (RT) group or a conventional training (CT) group. All outcome measures were assessed at the enrollment baseline (T0), 2nd week (T1) and 4th week (T2) of the treatment. The primary outcome was the between-group difference in the change in the Berg balance scale (BBS) score from baseline to T2. The secondary measures included longitudinal changes in the Fugl-Meyer assessment of the lower limb (FMA-LE), modified Barthel index (mBI), functional ambulation category (FAC), and locomotion assessment with gait analysis. In addition, the cortical activation pattern related to robot-assisted training was measured before and after intervention via functional near-infrared spectroscopy.

Results: A total of 30 patients with complete data were included in this study. Clinical outcomes improved after 4 weeks of training in both groups, with significantly better BBS (F = 6.341, p = 0.018, partial η2 = 0.185), FMA-LE (F = 5.979, p = 0.021, partial η2 = 0.176), FAC (F = 7.692, p = 0.010, partial η2 = 0.216), and mBI scores (F = 7.255, p = 0.042, partial η2 = 0.140) in the RT group than in the CT group. Both groups showed significant improvement in gait speed and stride cadence on the locomotion assessment. Only the RT group presented a significantly increased stride length (F = 4.913, p = 0.015, partial η2 = 0.267), support phase (F = 5.335, p = 0.011, partial η2 = 0.283), and toe-off angle (F = 3.829, p = 0.035, partial η2 = 0.228) on the affected side after the intervention. The RT group also showed increased neural activity response over the ipsilesional motor area and bilateral prefrontal cortex during robot-assisted weight-shift and gait training following 4 weeks of treatment.

Conclusions: Overground gait training with a unilateral exoskeleton robot showed improvements in balance and gait functions, resulting in better gait patterns and increased gait stability for stroke patients. The increased cortical response related to the ipsilesional motor areas and their related functional network is crucial in the rehabilitation of lower limb gait in post-stroke patients.

Keywords: Gait rehabilitation; Neuroplasticity; Stroke; Unilateral lower-limb exoskeleton robot.

Fig. 1

Schematic of the experimental design. (A) Experimental design. (B) fNIRS optode probe set. The fNIRS system consists of 21 light sources (shown in red) and 15 detectors (shown in blue), resulting in a total of 40 channels distributed over prefrontal, motor and occipital area in accordance with the international 10–20 system. (C) fNIRS measurement during robot-assisted overground gait training

Fig. 2

Flow diagram of the study

Fig. 3

Comparison of longitudinal clinical scores between the RT and CT groups. Significant within-group differences are marked with (* p < 0.05, ** p < 0.001). Significant between-group differences are marked with (# p < 0.05)

Fig. 4

Longitudinal cortical activation pattern in response to robot-assisted weight-shift training in the RT group. (A) Significant cortical activation maps in weight-shift training relative to rest tested by one sample t test with FDR correction. (B) Changes in the cortical activation response across the 4 weeks of training according to one-sample t tests with FDR correction. (C) Comparison of the LI for each cortex at each test with FDR correction

Fig. 5

Longitudinal cortical activation pattern in response to robot-assisted walking training in the RT group. (A) Significant cortical activation maps relative to the remaining maps were tested by one sample t test with FDR correction. (B) Changes in the cortical activation response following rehabilitation with FDR correction

Fig. 6

Relationships between motor recovery and cortical response changes related to robot-assisted weight-shift training (A) and robot-assisted walking training (B) from T0 to T1