Neurology · Medical Literature
Effect of mirror therapy combined with transcranial direct current stimulation on upper limb motor function in stroke patients: A meta-analysis.
Abstract
Upper limb motor impairment is a major contributor to long-term disability after stroke. Mirror therapy (MT) promotes motor relearning through visuomotor feedback, whereas transcranial direct current stimulation (tDCS) may facilitate neuroplasticity by modulating cortical excitability. We conducted a systematic review and meta-analysis to evaluate whether MT combined with tDCS provides additional benefits for poststroke upper limb rehabilitation. We searched PubMed, Embase, Web of Science, the Cochrane Library, CNKI, and Wanfang for randomized controlled trials (RCTs) published from 2015 to November 2025. Eligible studies enrolled adults with stroke-related upper limb motor deficits and compared MT + tDCS with MT alone or tDCS alone. Twelve RCTs involving 1024 participants were included. For Fugl-Meyer Assessment for Upper Extremity, MT + tDCS showed superior improvement versus MT alone (3 studies; I-squared statistic (I2) = 21.9%; MD = 12.65, 95% confidence interval [CI] 10.07-15.23) and versus tDCS alone (7 studies; I2 = 93.3%; MD = 7.03, 95% CI 3.76-10.31). For activities of daily living, the effect on Modified Barthel Index versus MT alone was highly heterogeneous and imprecise (2 studies; I2 = 94.7%; MD = 24.19, 95% CI - 144.99 to 193.38), whereas MT + tDCS significantly improved Modified Barthel Index versus tDCS alone (5 studies; I2 = 42.7%; MD = 9.29, 95% CI 6.36-12.22). For hand function, MT + tDCS improved Wolf Motor Function Test versus tDCS alone (3 studies; I2 = 80.3%; MD = 4.90, 95% CI 0.59-9.22). Reported adverse events were generally mild and transient. MT combined with tDCS appears to provide additional benefits for poststroke upper limb motor recovery, with consistent improvements in Fugl-Meyer Assessment for Upper Extremity and favorable effects on daily functioning and hand performance in key comparisons. However, heterogeneity across protocols and imprecision in some outcomes limit certainty. Larger, rigorously designed RCTs with standardized MT dosing and tDCS parameters and longer follow-up are warranted.
Clinical relevance
Upper limb motor impairment is a leading cause of long-term disability in stroke survivors, and standard rehabilitation strategies frequently yield incomplete recovery. This meta-analysis addresses a critical evidence gap by evaluating whether combining mirror therapy (MT) — a visuomotor feedback-based neurorehabilitation technique — with transcranial direct current stimulation (tDCS), a non-invasive cortical excitability modulator, produces synergistic neuroplastic benefits beyond either modality alone. With 12 RCTs and over 1,000 participants synthesized, this study provides the most current quantitative estimate of combination therapy efficacy and is immediately relevant to neurorehabilitation specialists managing post-stroke upper limb deficits.
Key findings
1. MT + tDCS versus MT alone (Fugl-Meyer Assessment for Upper Extremity [FMA-UE], 3 RCTs, n not individually specified): significant superiority of combination therapy (MD = 12.65, 95% CI 10.07–15.23; I² = 21.9%), with low heterogeneity strengthening confidence in this estimate. 2. MT + tDCS versus tDCS alone (FMA-UE, 7 RCTs): again significantly superior (MD = 7.03, 95% CI 3.76–10.31), though substantial heterogeneity was noted (I² = 93.3%), urging cautious interpretation. 3. MT + tDCS versus tDCS alone (Modified Barthel Index [MBI] for ADL, 5 RCTs): statistically significant improvement in daily functioning (MD = 9.29, 95% CI 6.36–12.22; I² = 42.7%), with moderate and acceptable heterogeneity. 4. MT + tDCS versus MT alone (MBI, 2 RCTs): the ADL effect was highly heterogeneous and statistically imprecise (MD = 24.19, 95% CI −144.99 to 193.38; I² = 94.7%), precluding meaningful conclusions for this comparison. 5. MT + tDCS versus tDCS alone (Wolf Motor Function Test [WMFT] for hand function, 3 RCTs): significant improvement in hand performance (MD = 4.90, 95% CI 0.59–9.22; I² = 80.3%), though high heterogeneity limits certainty. 6. Adverse events across all 12 included RCTs (1,024 participants total) were reported as generally mild and transient, suggesting an acceptable short-term safety profile for the combined intervention.
Practice implications
Neurorehabilitation clinicians should consider incorporating tDCS as an adjunct to structured mirror therapy protocols in adult stroke patients with residual upper limb motor deficits, as this combination demonstrates consistent and clinically meaningful gains in FMA-UE scores and ADL performance compared to either modality in isolation. However, given the very high heterogeneity in FMA-UE vs. tDCS-alone comparisons (I² = 93.3%) and the statistically imprecise MBI result vs. MT alone, patient selection should be guided by emerging protocol-specific data, and MT dosing parameters (session duration, frequency, total dose) as well as tDCS parameters (electrode montage, current intensity, stimulation duration) should be standardized and documented in clinical practice to facilitate future comparative effectiveness research. Larger, rigorously designed RCTs with longer follow-up are needed before definitive protocol recommendations can be established, and clinicians should monitor for — though expect to find minimal — adverse effects given the currently reassuring safety signal.