Effects of transcutaneous electrical nerve stimulation on upper limb recovery in stroke survivors: A systematic review and meta-analysis of randomized controlled trials.

Background: People with stroke commonly experience upper limb impairments. Transcutaneous electrical nerve stimulation is a noninvasive approach that delivers electrical signals to stimulate nerves.

Purpose: To evaluate the effectiveness of transcutaneous electrical nerve stimulation, with or without concurrent rehabilitation interventions, compared with passive or active controls, on upper limb motor recovery, spasticity, strength, range of motion, and dexterity post-stroke, and to identify optimal transcutaneous electrical nerve stimulation parameters.

Study design: Systematic review and meta-analysis.

Methods: A systematic search was conducted in PubMed, Scopus, MEDLINE, PEDro, REHABDATA, CINAHL, and EMBASE from inception to August 2024. Eligible studies were randomized controlled trials involving adults with stroke who received transcutaneous electrical nerve stimulation to the upper limb, alone or with rehabilitation interventions. Comparators included passive controls (eg, sham) or active controls (eg, conventional therapy). Studies assessed upper limb outcomes, including motor recovery, spasticity, strength, range of motion, or dexterity. Data were synthesized using Comprehensive Meta-Analysis Version 4. Study quality was assessed using the PEDro scale.

Results: Ten RCTs involving 744 post-stroke participants (mean age 61; 63% male) met inclusion criteria. Meta-analysis showed small, non-significant effects of TENS on functional recovery (SMD = 0.21, 95% CI: -0.15 to 0.57, p = 0.26; I² = 81%) and spasticity (SMD = 0.05, 95% CI: -0.35 to 0.44, p = 0.82; I² = 77%). Some studies reported significant improvements in strength, range of motion, and dexterity when TENS was combined with rehabilitation, though between-group differences were often not significant. Results for activities of daily living and quality of life were inconsistent and generally non-significant.

Conclusions: Transcutaneous electrical nerve stimulation alone shows limited effectiveness for upper limb recovery post-stroke. Combined with rehabilitation, it may offer additional benefits. Transcutaneous electrical nerve stimulation parameters should be individualized. More trials are needed to determine optimal applications in stroke rehabilitation.