Efficacy and safety of non-invasive brain stimulation for chronic low back pain: a systematic review and meta-analysis of randomised controlled trials

Non-invasive brain stimulation (NIBS), including transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS), is a potential treatment for chronic low back pain (CLBP). However, its efficacy and safety remain inconclusive. In this systematic review and meta-analysis, the clinical benefits of NIBS for pain relief, functional improvement, and quality of life (QoL) in patients with CLBP were evaluated. Five databases (PubMed, Web of Science, Cochrane Library, Embase and Scopus) were searched to identify randomised controlled trials (RCTs) of NIBS for CLBP. The final review included 21 RCTs involving 744 participants. The included studies assessed pain intensity, disability, and QoL outcomes, along with adverse events. Risk of bias (RoB) was evaluated using the RoB-2 tool, and meta-analyses were conducted using the R platform. NIBS was found to significantly reduce pain intensity (standardised mean difference [SMD] = − 0.85 [− 1.21, − 0.49]) and disability (SMD = − 0.52 [− 0.89, − 0.16]) compared with sham or control interventions. Subgroup analyses revealed that tDCS yielded broader benefits for both pain (SMD = − 0.80) and disability (SMD = − 0.59), while rTMS had the largest effect on pain reduction (SMD = − 1.09). tDCS targeting the primary motor cortex (M1) showed the strongest effects on pain relief (SMD = − 0.95) and functional improvement (SMD = − 0.59), while dorsolateral prefrontal cortex stimulation also yielded significant benefits for both pain (SMD = − 0.64) and disability (SMD = − 0.65). There is very low to moderate evidence that NIBS can help relieve pain and reduce disability in individuals with CLBP.