Peripheral somatosensory stimulation for post-stroke spasticity: a systematic review and network meta-analysis of randomized controlled trials

BACKGROUND: Post-stroke spasticity is common, disabling, and difficult to treat, and clinicians lack clear comparative evidence on which peripheral somatosensory stimulation (PSS) modality offers the greatest benefit. We aimed to compare and rank PSS modalities for reducing post-stroke spasticity. Eligible trials evaluated prespecified PSS modalities - transcutaneous electrical nerve stimulation (TENS/TEAS/TES), neuromuscular electrical stimulation (NMES), repetitive peripheral magnetic stimulation (rPMS), vibration, extracorporeal shock-wave therapy (ESWT), cryotherapy, and prolonged cutaneous/mechanical stimulation - versus sham/usual care or another active modality. Two reviewers independently screened records, extracted data, and assessed risk of bias using the 13-item Joanna Briggs Institute checklist. The primary outcome was end-of-treatment Modified Ashworth Scale (MAS). A fixed-effect network meta-analysis estimated by generalized least squares, preserving multi-arm covariance, generated pooled mean differences and treatment rankings (P-scores/SUCRA); inconsistency (design-by-treatment approach), small-study effects (comparison-adjusted Egger regression), and prespecified sensitivity analyses were used to test robustness. RESULTS: Of 1135 records identified, 38 RCTs met eligibility criteria and were included. The evidence network was predominantly control-centered with few head-to-head comparisons among active modalities. Compared with control (lower MAS indicates less spasticity), several interventions showed superior effects: rPMS (mean difference [MD] -1.34, 95% CI -1.54 to -1.14), cryotherapy (-0.99, -1.40 to -0.57), vibration (-0.56, -0.70 to -0.41), NMES (-0.45, -0.73 to -0.18), prolonged cutaneous/mechanical stimulation (-0.34, -0.53 to -0.16), and TENS (-0.18, -0.23 to -0.12). ESWT did not demonstrate a clear benefit (-0.10, -0.30 to 0.10). Ranking favored rPMS (P-score 0.990), followed by cryotherapy (0.860), vibration (0.676), NMES (0.567), prolonged cutaneous/mechanical stimulation (0.460), TENS (0.262), ESWT (0.161), and control (0.024). Global and local assessments revealed no material inconsistency, funnel plots and regression suggested no small-study effects, and results were stable across sensitivity analyses. CONCLUSIONS: Multiple PSS modalities reduce post-stroke spasticity on the MAS, with the highest probability of benefit observed for rPMS and cryotherapy, followed by vibration and NMES, while ESWT did not show a clinically meaningful effect. These findings can inform selection of PSS options in rehabilitation practice, but the control-centered, star-shaped network and limited head-to-head evidence highlight the need for rigorously concealed, intention-to-treat RCTs directly comparing leading modalities and optimizing stimulation parameters to refine clinical decision-making.