Somatosensory evoked potentials amplitude is enhanced after non-invasive brain stimulation in chronic ischemic stroke: Preliminary results from a randomised control trial.

OBJECTIVE: To investigate the effects of transcranial electrical and magnetic non-invasive brain stimulation (NIBS) protocols on somatosensory evoked potential (SEP) in chronic ischemic stroke. METHODS: 33 patients were randomly assigned to one of the four treatment groups of the transcranial direct current stimulation (tDCS) and/or repetitive transcranial magnetic stimulation (rTMS) protocol. SEP parameters were recorded before and after ten days of the treatment session. All the statistical analyses were carried out using SPSS version 19. RESULTS: It was found that there is a statistically significant improvement in the N20-P22 mean amplitude after treatment sessions in all groups except the group where tDCS and rTMS groups were sham. On paired t-tests, the difference betweeen post and pre-stimulation SEP amplitudes for the real tDCS and real rTMS coupled group was 1.045 ± 0.732 (p value = 0.005). For sham tDCS+real rTMS group, 1.05 ± 0.96 (P = 0.04); for real tDCS+sham rTMS 0.543 ± 0.332 (P = 0.01) and for double sham stimulation, 0.204 ± 0.648 (P =  0.4) respectively CONCLUSION: In ischemic stroke patients, either or coupled true transcranial tDCS and rTMS was found to be safe and significantly enhanced the amplitude of cortical somatosensory potentials when combined with standard physiotherapy, in the interim analysis of an ongoing randomised controlled trial. CLINICAL TRIAL REGISTRY OF INDIA: CTRI/2019/11/022009 SIGNIFICANCE: The results of this research indicates the importance of RCTs in developing robust improved NIBS protocols coupled to physiotherapy to enhance the sensory-motor functional recovery following ischemic stroke.

Short-term Effect of Noninvasive Brain Stimulation Techniques on Motor Impairment in Chronic Ischemic Stroke: A Systematic Review with Meta-Analysis.

Background: In recent years, noninvasive brain stimulation (NIBS) has shown promise for stroke rehabilitation as a novel nonpharmaceutical neuromodulatory intervention with attractive neurophysiological theories backing it up. Objective: To find out the short-term effects of NIBS techniques on motor impairment in chronic ischemic stroke. Materials and Methods: A systematic review with meta-analysis was performed separately for transcranial direct current stimulation (tDCS), transcranial magnetic stimulation (TMS), and studies that combined both, utilizing various databases for a period spanning from 2001 to 2019. Good-quality randomized controlled trials (RCTs) on chronic ischemic stroke cases with homogeneous clinical upper motor short-term outcome measures were considered for the meta-analysis. RevMan 5.1 software was used for the meta-analysis. Meta-analysis registration: CRD42021196299; https://www.crd.york.ac.uk/PROSPERO. Results: A total of 319 studies were identified initially. After necessary filters to comply with the strict recruitment criteria, only four studies qualified, two each for tDCS and TMS and none qualified for analysis under the combined category. tDCS showed a nonsignificant effect on the upper limb motor function improvement (-0.10 [95% confidence interval {CI}: -0.84 to 0.64; I2 0%; P = 0.8]), whereas the repetitive TMS showed a significant effect (0.75 [95% CI: 0.03-1.48; I2 0%; P = 0.04]). The safety analysis did not reveal any major concerns for several published protocols. Conclusions: tDCS alone did not significantly benefit motor recovery; rTMS was effective in providing immediate functional benefits in chronic ischemic stroke. While the current stroke rehabilitation protocols with NIBS appear safe, more good-quality stratified RCTs with more innovative experimental protocols are needed to analyze and quantify the efficacy of these techniques in stroke rehabilitation.