Effects of bilateral cutaneous electrical stimulation in improving lower limb motor functions and level of community integration in people with stroke

Abstract

Stroke is one of the leading causes of long-term disability globally. The residual physical impairments after stroke reduce both the quality and the quantity of the survivor's social participation. Transcutaneous electrical nerve stimulation (TENS) has been used to enhance the paretic lower limb motor functions in people with stroke. Besides, clinical studies demonstrated that the bilateral motor training was superior to unilateral training in improving the motor recovery in people with stroke. Current evidence showed that bilateral intervention recruits the spare neural substrates which can be utilized to enhance motor recovery. It was hypothesized that bilateral TENS (Bi-TENS) applied over both paretic and non-paretic legs induce greater and earlier improving in lower limb motor functions when compared to unilateral TENS (Uni-TENS). The aim of the work presented in this thesis was to compare the efficacy of Bi-TENS + task-oriented training (TOT) and Uni-TENS + TOT in enhancing motor recovery and augment the level of community integration in people with chronic stroke. This thesis starts with a systematic review and meta-analyses that summarised the effects of TENS on lower-limbs motor recovery in people with stroke. Results of the meta-analysis indicates that TENS is effective at enhancing walking capacity and reducing spasticity. The subsequence cross-sectional study 2 and 3 investigate the influence of assessment procedures of Berg Balance Scale and Five-Times-Sit-to-Stand Test. Results of these studies showed that selection of weight-bearing leg affects the Berg Balance Scale total score, and the arm positions or foot placements affects the Five-Times-Sit-to-Stand Test completion time. Thus, standardising the assessment procedure is necessary for using these outcomes in the randomised control trial. Study 4 describes the translation and validation processes of the Subjective Index of Physical and Social Outcome. Results show that the translated questionnaire is reliable and valid to measure the level of community integration in people with stroke in Hong Kong. Study 5 evaluates the relationship between physical functions and level of community integration in community-dwelling people with stroke. Results show that paretic ankle dorsiflexion strength, walking endurance and balance performance were predictors of the level of community integration. Therefore, this study forms the rationale of measuring the level of community integration in the randomised control trial Study 6 is the main study which compares the efficacy of the Bi-TENS + TOT versus Uni-TENS + TOT in improving paretic ankle muscle strength, balance performance, walking capacity and level of community integration in people with chronic stroke. Eighty subjects were randomly assigned to Bi-TENS + TOT or Uni-TENS +TOT group and received 20-session of training. Results showed that Bi-TENS with TOT was superior to Uni-TENS with TOT in improving the paretic ankle dorsiflexion strength after 10-session of training and Timed Up and Go test completion time after 20-session of training. Since the neurophysiological machanism that mediate the effects of Uni-TENS and Bi-TENS remains unclear, study 7 aims to evaluate the effects of Bi-TENS and Uni-TENS on cortical perfusion and motor performance in healthy older adults. The results showed that Bi-TENS applied over the peroneal nerve reduced the maximal change of Oxyhaemogobin concentration during isometric ankle dorsiflexion when compared to placebo stimulation and Uni-TENS. However, there was no significant difference existed in motor performance.