Effects of transcutaneous electrical nerve stimulation on spasticity in individuals with spinal cord injury: A systematic review and meta-analysis

CONTEXT: Spasticity is among the most common impairments following spinal cord injury (SCI). Transcutaneous electrical nerve stimulation (TENS) is a modality that delivers noninvasive electrical stimulation to peripheral nerves. OBJECTIVES: This review aims to investigate the effects of TENS on spasticity in individuals with SCI. METHODS: PubMed, Scopus, MEDLINE, REHABDATA, PEDro, CINAHL, EMBASE, and Web of Science were searched from inception to June 2026. Experimental studies investigating the effects of TENS on spasticity in individuals with SCI were included. Methodological quality was assessed using the Cochrane Risk of Bias 2 tool and the PEDro scale. Certainty of evidence was evaluated using the GRADE framework. RESULTS: ² = 92%). In contrast, pooled analysis of neurophysiological outcomes showed no significant effect on H/M ratio (SMD = 0.00, 95% CI -0.05-0.05). Individual study findings were inconsistent, and overall methodological quality ranged from poor to fair. The certainty of evidence was rated as low. No adverse events were reported. CONCLUSIONS: TENS may be associated with improvements in clinically assessed spasticity in individuals with SCI; however, these findings should be interpreted with caution due to substantial heterogeneity, small sample sizes, and low-certainty evidence. High-quality randomized controlled trials with standardized protocols and comprehensive outcome measures are required to establish the effectiveness and mechanisms of TENS in SCI-related spasticity.