Functional connectivity-targeted high-definition transcranial infraslow grey noise stimulation for chronic low back pain: protocol for a double-blinded, randomised, controlled clinical trial.

Introduction: Chronic low back pain (CLBP) is a disabling condition worldwide, with unsatisfactory treatment outcomes, warranting newer therapies. Brain imaging demonstrates altered functional connectivity among three pain processing networks; salience network (SN), default mode network (DMN) and somatomotor network (SMN). Treatments targeted to change the functional connectivity among these networks may produce clinical benefits. This trial will evaluate the efficacy of a novel non-invasive brain stimulation technique targeting the functional connectivity among the SN, DMN and SMN for improving pain intensity in people with CLBP.

Methods And Analysis: A single-centre double-blinded randomised two-arm placebo-controlled parallel phase II efficacy trial will be conducted at the University of Otago (Dunedin, New Zealand). Participants (n=164) with CLBP will be randomised (1:1) to receive 12 sessions (three per week) of either sham or active stimulation. The primary endpoint will be the change in average pain intensity from baseline to 1 week post completion of intervention. Secondary outcome measures include clinical, functional, psychological, quantitative sensory testing and electroencephalography collected at baseline, 1 week post completion of intervention and at follow-up of 1, 3, and 6 months post intervention. Linear mixed model analyses will be used to evaluate the efficacy of the intervention on the primary outcome.

Ethics And Dissemination: Ethical approval has been obtained from Northern B Health and Disability Ethics Committee, New Zealand (Ref: 2024 FULL 21891). All participants will provide written informed consent. Findings will be reported to the funding and regulatory bodies, presented at national/international conferences and published in scientific journals.

Trial Registration Number: ClinicalTrials.gov, NCT06902233.