Effects of transcranial direct current stimulation on motor function in patients with multiple sclerosis: a systematic review and meta-analysis

Clinical Snapshot

Key Findings

• P Value: p < 0.0001 (primary lower limb outcome); walking distance p = 0.0005; static balance (BBS) p = 0.0002; walking speed and dynamic balance not significant; upper limb dexterity (9-HPT) p = 0.11 (non-significant)

• Effect Size: SMD = 0.31 (small-to-moderate effect favouring tDCS over control)

• Primary Outcome: Lower limb motor function in MS patients (composite of walking distance, walking speed, static balance, and dynamic balance)

• Nnt Or Sensitivity: NNT not calculable from SMD alone without minimal clinically important difference (MCID) data for the composite outcome. For the Berg Balance Scale, the MCID is approximately 6 points; clinical significance of the observed effect cannot be confirmed without raw mean differences. Stimulation subgroup: 2.0–2.5 mA significant (p = 0.007); 20-minute duration significant (p = 0.03).

• Confidence Interval: 95% CI: 0.16 to 0.46

Clinical Application

tDCS is a relatively low-cost, non-invasive neurostimulation technique with a favourable safety profile in general populations. Equipment is commercially available and can be administered in outpatient rehabilitation or home settings. However, optimal electrode placement for MS motor circuits requires trained personnel. The evidence base is insufficient to support routine clinical implementation without further large-scale RCTs. tDCS devices are not currently listed on the Australian Register of Therapeutic Goods (ARTG) for MS-specific indications and are not PBS-subsidised. The RACGP and MS Australia do not currently include tDCS in standard MS management guidelines. Australian neurologists and rehabilitation physicians should regard tDCS as investigational for MS motor rehabilitation. The National Disability Insurance Scheme (NDIS) may fund allied health interventions incorporating neurostimulation on a case-by-case basis. Australian MS cohorts are predominantly Caucasian with different genetic and environmental risk profiles compared to populations likely represented in Chinese-institution-led reviews, warranting caution in direct extrapolation. Adults with relapsing-remitting or progressive MS experiencing lower limb motor impairment, particularly walking and balance deficits. Applicability to upper limb fine motor dysfunction is not supported by current evidence.

Abstract

OBJECTIVE: To assess the effectiveness of transcranial direct current stimulation (tDCS) in enhancing motor function recovery in the upper and lower extremities of individuals with multiple sclerosis. DATA SOURCES: PubMed, Embase, Web of Science, Cochrane Library, and China Knowledge Network (CNKI) databases from inception until December 28, 2025. STUDY SELECTION: Randomized controlled trials that investigated transcranial direct current stimulation and tDCS combined with physical training on motor function in the upper and lower limbs of individuals with MS. DATA EXTRACTION: Two reviewers extracted the data and assessed the risk of bias. Standardized mean difference (SMD) and 95% confidence intervals (CI) were calculated using a random-effects model based on heterogeneity. The analysis included 10 articles with a total of 299 subjects. DATA SYNTHESIS: The Meta-analysis shows tDCS significantly improves lower limb motor function in MS patients (SMD = 0.31, 95% CI: 0.16 - 0.46, p < 0.0001). Subgroup analyses found significant increases in walking distance (p = 0.0005) and static balance (Berg Balance Score, p = 0.0002), but no significant improvements were observed in walking speed and dynamic balance. For upper limb motor function, no statistically significant difference was found in hand dexterity (9-HPT) (p = 0.11). Notably, subgroup analyses of stimulation parameters showed that high intensity (2.0-2.5 mA, p = 0.007) and a 20-minute duration (p = 0.03) yielded significant effects, whereas low intensity (1.0-1.5 mA) and 15-minute duration showed no significant benefits. CONCLUSIONS: Transcranial direct current stimulation is effective in enhancing lower limb motor function in patients with MS. However, the efficacy of tDCS in improving upper limb fine motor skills remains unclear. Evidence suggests that stimulation at 2.0-2.5 mA for 20 min may be the optimal protocol for clinical intervention.

References

1. 1.Zhang, J., Wu, Y., Chen, S., & Wang, Y. (2026). Effects of transcranial direct current stimulation on motor function in patients with multiple sclerosis: a systematic review and meta-analysis. Neurological Sciences: Official Journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology. https://doi.org/10.3389/fpsyt.2014.00086