Transcranial direct current stimulation (tDCS) of the left dorsal anterior cingulate cortex (dACC) may be associated with improvements in pain-related function, distress, and depression in patients with chronic low back pain, according to a study published in Pain Medicine.
A total of 21 patients age >18 with chronic low back pain and on stable medications for ≥1 month treated at the Providence Veterans Affairs Medical Center and Butler Hospital in Rhode Island were enrolled in the study. Study participants were randomly assigned to receive 10 weekday 2-mA active tDCS sessions (n=10) or a sham intervention (n=11), with each session lasting approximately 20 minutes. During each active tDCS session, physicians placed a cathodal electrode over FC1 and an anodal return electrode over the contralateral mastoid.
Researchers surveyed participants on pain acceptance (using the Chronic Pain Acceptance Questionnaire [CPAQ-8]), pain-related anxiety (with the Pain Anxiety Symptoms Scale [PASS-20]), disability (using the Roland Morris Disability Questionnaire [RMDQ]), pain interference (with the 18-item West Haven-Yale Multidimensional Pain Inventory’s General Activity Subscale [WHY-MPI-C]), pain intensity (with the 11-item Defense and Veterans Pain Rating Scale [DVPRS]), and general anxiety and depression (using the 9-item Patient Health Questionnaire [PHQ-9]).
Pain intensity was not found to differ between active treatment and sham tDCS at days 1, 5, and 10 or at the 6-week follow-up (P >.58 for all). Study participants treated with active tDCS vs sham control reported lower pain interference (P =.002), lower pain disability (P =.001), and reduced depression (P =.003) at 6 weeks.
Limitations of the analysis include its short follow-up and the small number of patients in the final cohort.
“Future studies…should consider additional cortical targets, high-density multi-electrode arrays for better spatial resolution, and neuroimaging (instead of the electrode field modeling done in our study) to demonstrate engagement of desired cortical targets,” noted the study authors.
Mariano TY, Burgess FW, Bowker M, et al. Transcranial direct current stimulation for affective symptoms and functioning in chronic low back pain: A pilot double-blinded, randomized, placebo-controlled trial [published online October 24, 2018]. Pain Med. doi:10.1093/pm/pny188