Immediate Effects of Dry Needling on Central Pain Processing and Skin Conductance in Patients with Chronic Nonspecific Neck Pain: A Randomized Controlled Trial

Abstract

Although current evidence supports the use of dry needling for improving some clinical outcomes in people with neck pain, no previous research explored the effects of dry needling on the central processing of pain and autonomic nervous system in this population. Therefore, this clinical trial aimed to compare the effects of real and sham dry needling on autonomic nervous system function, pain processing as well as clinical and psychological variables in patients with chronic nonspecific neck pain. A double-blinded randomized clinical trial including 60 patients with neck pain was conducted. Patients were randomized to the real needling (n = 30) or sham needling (n = 30) group. Skin conductance (SC), pressure pain thresholds (PPTs), temporal summation (TS), conditioned pain modulation (CPM) as well as pain intensity, related-disability, catastrophism, and kinesiophobia levels were assessed by an assessor blinded to the allocation intervention. The results did not find significant group * time interactions for most outcomes, except for the global percentage of change of SC values (mean: F = 35.90, p < 0.001, ηp2 = 0.459; minimum: F = 33.99, p = 0.839, ηp2 = 0.371; maximum: F = 24.71, p < 0.001, ηp2 = 0.037) and PPTs at C5-C6 joint in the same side of needling (F = 9.982; p = 0.003; = 0.147), in favor of the dry needling group. Although the proportion of subjects experiencing moderate to large self-perceived improvement after the intervention was significantly higher (X2 = 8.297; p = 0.004) within the dry needling group (n = 18, 60%) than in the sham needling group (n = 7, 23.3%), both groups experienced similar improvements in clinical and psychological variables. Our results suggested that dry needling applied to patients with chronic nonspecific neck pain produced an immediate decrease in mechanical hyperalgesia at local sites and produced an increase in skin conductance as compared with sham needling. No changes in central pain processing were observed. A single session of sham or real dry needling was similarly effective for decreasing related disability, pain intensity, catastrophism, and kinesiophobia levels. Further studies are needed to better understand the clinical implications of autonomic nervous system activation on central sensitization and pain processing in the long-term after the application of dry needling.