Transcutaneous electrical nerve stimulation for treatment of primary dysmenorrhea: A systematic review and meta-analysis of randomized controlled trials

Primarily dysmenorrhea (PD) occurs in about 50%-90% of individuals who menstruate and is a painful cramping of the uterus with nausea, fatigue, and impairment of functionality. Nonsteroidal anti-inflammatory drugs (NSAIDs) and hormonal contraceptives are also popular treatment, but their effectiveness might not be high, and some adverse effects might limit their use over the long term. Non-invasive analgesic modality, Transcutaneous electrical nerve stimulation (TENS), is a non-invasive stimulation technique that alters pain by its peripheral and central mechanisms. It was a systematic review and meta-analysis study that attempted to assess the effectiveness and safety of the TENS in the management of primary dysmenorrhea through the synthesis of randomized controlled trials (RCTs) evidence. In accordance with the PRISMA 2020 guidelines, the extensive search of PubMed, Scopus, Web of Science, and Cochrane Library located English-language RCTs that compared TENS to control interventions in PD patients. Two reviewers carried out the study selection, data extraction, and risk-of-bias assessment using the RoB 2 tool. Primary outcomes that included Visual Analog Scale (VAS) pain scores, duration of pain reduction, and ibuprofen use, and secondary outcomes that included lower abdominal pain, lower back and thigh referred pain, and Brief Pain Inventory (BPI) scores were analyzed by use of random-effects models to pool mean differences (MD) or standardized MD (SMD). RevMan version 5.3 was used to conduct statistical analysis. It included 13 RCTs that had 779 participants. TENS had a significant impact on the intensity of menstrual pain (MD −1.97, 95% CI −3.13 −0.81), the length of pain relief (SMD 0.78, 95% CI 0.54 to 1.02), and the reduction of the intake of ibuprofen (MD -1.29, 95% CI −2.54 to −0.05). There were also significant changes in lower abdominal pain (SMD −1.33, 95% CI −1.60 −1.07), lower back pain (SMD −1.60, 95% CI −1.96 −1.25) and bilateral thigh pain (SMD −1.39, 95% CI −1.71 −1.06) and No significant difference in BPI scores (MD 0.01, 95% CI −0.37 −0.4 TENS was also tolerated and no major adverse events were reported. Altogether, TENS seems to be an effective and safe non-pharmacological treatment for decreasing the severity of pain and analgesic consumption in primary dysmenorrhea, yet the impact of TENS on the functional disability is not clear, which necessitates further high-quality and standardized studies to conclude on the best treatment regimens and protracted results.