Differences in central neural pain processing following acupuncture and sham acupuncture therapy in fibromyalgia (FM)

Clinical trials of acupuncture for the treatment of chronic pain conditions such as fibromyalgia (FM) have resulted in equivocal findings. In most studies, traditional acupuncture and sham acupuncture are equally effective. However no study has used functional magnetic resonance imaging (fMRI) in FM patients to examine more detailed changes in central pain processing following traditional and sham acupuncture. 25 female FM participants were randomized to receive either 9 sessions of traditional Chinese acupuncture (TA; n =13; mean(SD)age=48.9(11.3)yrs) or 9 sessions of sham acupuncture (SA; n=12; mean(sd)age=42.9(13.6)yrs) over the course of one month. Neural activity evoked by painful pressures applied to the thumbnail was assessed pre- and post-treatment with fMRI. Clinical (Short Form of the McGill Pain Questionnaire; SFMPQ) and experimental pressure pain were assessed pre- and post-treatment. The entire cohort displayed reductions in both clinical and experimental pain (SFMPQ total mean(SD)change=5.15(5.65), p=0.001; mild pressure pain threshold mean(SD)change kg=0.58(0.85), p=0.003), however no significant differences in the amount of pain reduction were detected between groups for either pain dimension (both p>0.15). Significant differences in pain evoked neural activity were detected between TA and SA for the inferior parietal lobule (Z=3.5; p<0.001 uncorrected) and two regions in the cerebellum (region 1: Z=3.08; p=0.001 uncorrected; region 2: Z=3.2; p<0.001 uncorrected). In these regions greater reductions in pain evoked activity were detected following TA. Other regions within the cerebellum and the posterior cingulate showed trends towards greater reductions following TA (p<0.002 uncorrected). No regions were detected that showed greater reductions in neural activity following SA. Although both TA and SA resulted in similar reductions in pain report, fMRI was able to detect differences between these two treatments. fMRI may be more sensitive at detecting changes in pain processing than subjective pain report.

Funding:

Department of Army grant DAMD-17/002-0018

NIH grants M01-RR000042 and K01 AT01111-01.