Efficacy of transcranial electrical stimulation in the treatment of chronic nonspecific low back pain: a systematic review and meta-analysis.

INTRODUCTION: Chronic nonspecific low back pain (CNLBP) is a prevalent condition associated with substantial disability and a marked reduction in quality of life. First‑line treatments, such as pharmacotherapy and physical therapy, often have limited effectiveness. This systematic review and meta‑analysis evaluated the efficacy of transcranial electrical stimulation (tES) modalities, including transcranial direct current stimulation (tDCS), high‑definition transcranial direct current stimulation (HD‑tDCS), and transcranial alternating current stimulation (tACS), for the treatment of CNLBP. METHODS: A comprehensive search was conducted across six electronic databases, and 19 randomized controlled trials met the inclusion criteria. Of these, 15 studies evaluated conventional tDCS, two evaluated high‑definition tDCS, one evaluated high‑definition transcranial infraslow pink‑noise stimulation (HD‑tIPNS), and one evaluated tACS. RESULTS: The pooled results showed that single‑session tDCS did not significantly reduce pain intensity compared with sham. However, when combined with physical or behavioral interventions, tDCS was associated with significant pain reduction. Subgroup analyses showed no significant differences in outcomes according to stimulation target, including the primary motor cortex and dorsolateral prefrontal cortex. DISCUSSION: Although tDCS showed promise as an adjunct for pain relief, its effects on functional disability and psychological outcomes were less conclusive. Further high‑quality studies are needed to optimize stimulation protocols and clarify the role of tDCS as an adjunct to other therapeutic approaches. SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD420261298298, CRD420261298298.