Efficacy of repetitive transcranial magnetic stimulation for improving lower limb function in individuals with neurological disorders: A systematic review and meta-analysis of randomized sham-controlled trials

Abstract

Objective: To determine the efficacy of repetitive transcranial magnetic stimulation vs sham stimulation on improving lower-limb functional outcomes in individuals with neurological disorders. Data sources: PubMed, CINAHL, Embase and Scopus databases were searched from inception to 31 March 2020 to identify papers (n = 1,198). Two researchers independently reviewed studies for eligibility. Randomized clinical trials with parallel-group design, involving individuals with neurological disorders, including lower-limb functional outcome measures and published in scientific peer-reviewed journals were included. Data extraction: Two researchers independently screened eligible papers (n = 27) for study design, clinical population characteristics, stimulation protocol and relevant outcome measures, and assessed study quality. Data synthesis: Studies presented a moderate risk of selection, attrition and reporting bias. An overall effect of repetitive transcranial magnetic stimulation was found for outcomes: gait (effect size [95% confidence interval; 95% CI]: 0.51 [0.29; 0.74], p = 0.003) and muscle strength (0.99 [0.40; 1.58], p = 0.001) and disorders: stroke (0.20 [0.00; 0.39], p = 0.05), Parkinson’s disease (1.01 [0.65; 1.37], p = 0.02) and spinal cord injury (0.50 [0.14; 0.85], p = 0.006), compared with sham. No effect was found for outcomes: mobility and balance. Conclusion: Supplementary repetitive transcranial magnetic stimulation may promote rehabilitation focused on ambulation and muscle strength and overall lower-limb functional recovery in individuals with stroke, Parkinson’s disease and spinal cord injury. Further evidence is needed to extrapolate these findings. Lay abstract Non-invasive magnetic brain stimulation can cause beneficial changes in the central nervous system of individuals with neurological disorders, which, in turn, may have a number of therapeutic qualities. This paper summarizes current knowledge about whether the technique can be used to promote recovery of leg movement function. By searching the available literature for studies on individuals with neurological disorders that have compared the effects of magnetic brain stimulation with placebo stimulation, 27 relevant studies were identified. Combined data from these studies suggested that real stimulation, compared with placebo, had positive effects specifically for recovery of walking ability and maximal leg muscle strength, as well as for improvement in overall leg movement function in individuals with stroke, Parkinson’s disease and spinal cord injury. These findings are important for patients and therapists seeking to improve rehabilitation outcomes. This research area deserves increased scientific focus.

Keywords

• transcranial magnetic stimulation
• neurological disorders
• lower extremity