A sham-controlled trial found evidence of the placebo effect among patients with fibromyalgia (FM) in which patients had decreased pain after sham transcranial direct current simulation (tDCS). These findings were published in the journal Pain.
Women (N=130) with FM were recruited at 5 centers in Galicia, Spain between 2017 and 2019 for this longitudinal, randomized, sham-controlled, double-blind clinical trial. Patients were randomized to receive tDCS over the primary motor cortex (M1; n=34), dorsolateral prefrontal cortex (DLPFC; n=33), operculo-insular cortex (OIC; n=33), or sham (n=30) treatment administered during 15 sessions lasting 20 minutes. Outcomes were measured at 6 and 12 months by a variety of validated instruments.
The M1, DLPFC, OIC, and sham cohorts comprised women aged mean 49.38, 50.55, 50.21, and 50.67, respectively. Overall, 78.8% used pain medication including antidepressants (53.8%) and opioids (32.6%).
Significant improvements were observed for pain, fatigue, mood disturbances, and sleep quality up to 6 months (all P <.05) regardless of treatment assignment.
Pain, according to a numerical rating scale, fluctuated at every session but tended to trend downward.
There was a significant time by group effect for anxiety and depression among the M1 (P =.037), DLPFC (P =.002), and OIC (P =0.000) groups but not for the sham cohort (P =.438).
Adverse effects lasting 5 days among the active and sham cohorts were tickling (42.9% vs 57.7%), itching (46.4% vs 53.8%), and burning (28.6% vs 30.8%), respectively.
This study may have been limited by only stimulating targets on the left hemisphere, however, this was consistent with previously published trials.
The study authors observed an improvement to pain as well as fatigue, mood, and sleep among women with FM after receiving active or sham tDCS treatment at 3 differing targets. As pharmacological treatments for FM have been shown to have limited benefit, tDCS therapy may be a viable alternative.
Samartin-Veiga N, Pidal-Miranda M, González-Villar AJ, et al. Transcranial direct current stimulation of three cortical targets is no more effective than placebo as treatment for fibromyalgia: a double-blind sham-controlled clinical trial. Pain. Published online September 23, 2021. doi:10.1097/j.pain.0000000000002493