Targeting symptoms of fibromyalgia through transcutaneous electrical nerve stimulation (TENS): a systematic review of current systematic reviews

BACKGROUND: Fibromyalgia syndrome (FMS) is a chronic condition characterized by widespread musculoskeletal pain, fatigue, and cognitive dysfunction. Considering that current treatments often provide limited relief, interest has grown in non-pharmacological options such as transcutaneous electrical nerve stimulation (TENS). OBJECTIVE: To systematically and critically assess and synthesize current evidence from systematic reviews and meta-analyses on the efficacy and safety of TENS for managing symptoms of FMS. METHODS: An umbrella review was conducted in accordance with the PRISMA 2020 guidelines. Databases including PubMed, Scopus, Embase, Web of Science, and Cochrane Library were searched in April 2024 for systematic reviews and meta-analyses evaluating TENS in adults with FMS. Reviews were included if they reported symptom-related outcomes such as pain, fatigue, sleep, function, or quality of life. Data extraction and risk of bias assessment were performed independently by 2 reviewers. The GRADE approach was used to assess the certainty of evidence, and a narrative synthesis was conducted due to heterogeneity. RESULTS: Nine systematic reviews, encompassing a broad range of TENS protocols and study populations, were included. TENS provided short-term pain relief, particularly when applied at higher intensities in treatment courses of 10 or more sessions. Functional and psychosocial outcomes were inconsistently reported and typically did not show clinically significant improvements. TENS was reported as safe and well-tolerated across all reviews. Methodological quality of the included systematic reviews was predominantly high. However, GRADE assessment indicated low to moderate certainty for pain reduction with TENS, very low to low certainty for functional outcomes, and moderate certainty for its effects on pain modulation in fibromyalgia. CONCLUSIONS: While TENS appears to be a safe and potentially effective adjunct for short-term pain relief and enhancing pain modulation, the overall evidence remains limited by inconsistency and low certainty regarding functional improvements.