Effects of unilateral and bilateral cutaneous electrical stimulation on upper limb functions in patients with chronic stroke

Abstract

Stroke is recognized as a global disease which could lead to long-term disability. The upper limb impairment in motor control is one of the common sequelaes in people with chronic stroke. About one-third of the people with stroke suffered upper limb motor function deficit six months after stroke, which could be a great burden for them return to the normal daily lives. Therefore, one of the main goals of stroke rehabilitation is to enhance the motor recovery of the paretic upper limb among people with stroke. Evidence showed that transcutaneous electrical nerve stimulation (TENS) was an effective intervention to enhance the motor recovery of upper limb in people with stroke when combined with task-oriented training (TOT). In addition, the bilateral upper limb exercise was found to induce significant greater improvement of upper limb motor control than the unilateral upper limb exercise in people with stroke. The bilateral exercise could recruit the pathway in both the intact and lesioned hemisphere to elicit a greater cortical activation so as to enhance the upper limb motor recovery in people with stroke. Based on the evidence that the combination of TENS and TOT is an effective intervention in enhancing the upper limb motor recovery, and given the advantage of bilateral exercise can recruit more neural pathway to elicit greater cortical activation, it is reasonable to hypothesize that bilateral TENS (Bi-TENS) could augment the effect of TOT of upper limb motor recovery in people with stroke. Hence, the aim of this study is to investigate whether Bi-TENS+TOT is superior to unilateral TENS (Uni-TENS)+TOT, Placebo-TENS+TOT and control without any active treatment in improving the motor function of upper limb in people with chronic stroke. This thesis started with a systematic review and meta-analysis (Study 1) of comparing the effect of bilateral upper limb exercise with unilateral upper limb exercise on the recovery of upper limb motor control and functional performance in people with chronic stroke. The result of the current studies indicated that bilateral form of upper limb exercise was superior to unilateral upper limb exercise in enhancing the recovery of the upper limb motor control in people with stroke. Study 2 investigated the impacts of self-perceived performance of the paretic upper limb on the recovery of the functional performance of paretic upper limb in people with stroke when controlled the influence from the upper limb motor control. The self-perceived performance, hand motor control and functional performance of paretic upper limb was measured by Motor Activity Log (MAL), hand subscale of Fugl-Meyer Assessment (FMA-hand) and Action Research Arm Test (ARAT), respectively. The finding of the study showed that the MAL score was a significant predictor of ARAT score in people with stroke, when the impact of FMA-hand was controlled. In order to improve ARAT score after intervention, assessment and training protocol about self-perceived performance of upper limb functions should be included in the main study. Study 3 is our main study which compared the effect of Bi-TENS+TOT with Uni-TENS+TOT, Placebo-TENS+TOT and control without active treatment in improving the upper limb motor control, muscle strength of upper limb, abnormal muscle activation, range of motion, functional performance of upper limb, performance of daily function of upper limb, self-perceived performance of upper limb and community integration level in people with chronic stroke. Total one hundred and twenty subjects were randomly assigned to Bi-TENS+TOT, Uni-TENS+TOT, Placebo-TENS+TOT and Control group. Among the four groups, the subjects in Bi-TENS+TOT, Uni-TENS+TOT and Placebo-TENS+TOT group received twenty sessions of intervention, while the Control group did not receive any active treatment. The primary outcome was FMA-UE score, while the secondary outcomes included peak torque and co-contraction ratio of wrist flexion/extension during maximum isometric voluntary contraction (MIVC), active range of motion of wrist flexion/extension, elbow flexion/extension, Jacket Test completion time, ARAT, MAL and Community Integration Measure score. These outcome measures were measured among the four groups in baseline, mid-intervention, immediately post-intervention, one-month follow-up and three-month follow-up assessment. The result showed that the patients in Bi-TENS+TOT group got a significantly greater between-group improvement than Uni-TENS+TOT beginning from post-intervention assessment. While a significantly greater between-group improvement of FMA-UE score was shown in Bi-TENS+TOT group than Placebo-TENS+TOT and Control group beginning from mid-intervention assessment and maintained in one-month follow-up and three-month follow-up. Both the Bi-TENS+TOT and Uni-TENS+TOT group showed significant within-group improvement in FMA-UE at post-intervention assessment when compared with baseline. The Bi-TENS+TOT showed an earlier within-group improvement than Uni-TENS+TOT in the improvement of FMA-UE score. Only the patients in Bi-TENS+TOT group showed significant within-group improvement in peak torque during MIVC of wrist flexion and ARAT score in post-intervention assessment when compared with baseline. The significant improvement was maintained in one-month follow-up and three-month follow-up.