Double-blind randomized control trial investigating immediate changes in pain processing measures in response to dry needling to the lumbar multifidus in an asymptomatic population.

INTRO: Dry needling (DN) is a conservative treatment for managing low back pain. Knowledge of the mechanisms by which DN modulates pain provides insight into matching this intervention to subgroups within the low back pain population with the potential to enhance outcomes. Quantitative sensory testing (QST) is an assessment of somatosensory responses to noxious stimuli. Measuring QST pre- and post-intervention informs mechanisms through which DN modulates pain.

METHODS

An asymptomatic convenience sample was recruited. Pre and post-intervention QST measures established pain sensitivity profiles. Participants were randomized to DN or sham DN to the lumbar multifidus. Participant expectations for changes in pain sensitivity were assessed immediately before and after needling. Blinding was assessed immediately after participants received the needling intervention. Repeated measures ANOVAs assessed between group by time differences and correlation coefficients assessed for factors associated with significant QST change scores.

RESULTS

34 participants completed the study. A significant main effect of time was observed for PPT at the low back (P = 0.04, 95 % CI: 0.60;-0.01), partial eta squared 0.12. Baseline conditioned pain modulation efficiency and post-needling expectation were significantly correlated to PPT change scores at r = 0.45 (p < 0.01) and r = -0.39 (p = 0.02).

CONCLUSION

A significant main effect was observed in response to DN and sham DN local to the intervention site. This finding suggests peripherally mediated shared mechanisms between DN and sham DN. Baseline pain modulatory efficiency and post-intervention expectations may be indicators of individuals who will experience a greater analgesic response to needling interventions.