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A home-based anodal transcranial direct current stimulation (tDCS) of the dorsoprefrontal cortex of individuals with fibromyalgia may provide significant pain relief when used for an extended period, according to study results published in the Journal of Pain.
The use of tDCS has been associated with greater efficacy in some patients with fibromyalgia compared with pharmacologic treatment, but the therapy is generally administered under supervision in a medical setting.
In this randomized double-blind sham-controlled trial (ClinicalTrials.gov identifier: NCT02652988), 20 right-handed women aged 18 to 65 years with a diagnosis of fibromyalgia were enrolled between January 2017 and July 2018. Study participants had to have a pain score ≥50 on a 0 to 100 visual analog scale (VAS) to be included. Following in-person training on a special tDCS device designed for in-home self-administration, participants were randomly assigned to receive active tDCS (n=10; mean age, 48.6 years; fibromyalgia duration, 5.75 years) or sham tDCS (n=10; mean age, 49.7 years; fibromyalgia duration, 6.62 years) 5 days a week for a period of 12 consecutive weeks (60 sessions).
The procedure was performed at 2 mA for 30 minutes, with the anode and cathode placed over the left and right dorsolateral prefrontal cortices, respectively. The study’s primary outcome was the VAS pain score in the last 24 hours. Secondary outcomes included pain-related disability, analgesic use, psychological symptoms, and quantitative sensory test results. Serum levels of brain-derived neurotropic factor (BDNF) were measured at baseline and at 12 weeks.
After 20 sessions, participants who had received active tDCS had a 45.65% reduction in cumulative pain scores from baseline (mean VAS scores, 7.25±1.43 to 3.94±1.14), compared with a 27.74% reduction (mean VAS scores, 7.10±1.81 to 5.13±0.90) in participants in the sham tDCS group (P =.01). After 60 sessions, pain reduction was also greater in patients receiving active vs sham stimulation (reduction, 62.06%; 7.25±1.43 to 2.75±0.80 vs 24.92%; 7.10±1.81 to 5.33±0.81, respectively; P <.0001). The intragroup effect size at 12 weeks was 3.14 and 0.97 in the active and sham stimulation, respectively (intergroup effect size, 1.59).
At 12 weeks, participants who had received active vs sham stimulation reported greater total score reductions on the Brazilian version of the Profile of Chronic Pain screen (P <.001), as well as on the interference in daily life activities and emotional burden subscales (P <.01 and P <.009, respectively). In addition, participants receiving active vs sham tDCS reported greater reductions in analgesic use (55% vs 35%, respectively; P <.03). Serum levels of BDNF were inversely correlated with VAS pain scores, with higher levels predicting larger decreases in pain than lower VAS scores (P =.01).
Study limitations include the sole recruitment of women and a lack of extended follow-up to assess long-term effects.
“The results provide additional data to use the [dorsolateral prefrontal cortex] as a target for the treatment of fibromyalgia,” noted the authors. “The serum BDNF may be a valuable predictor of the magnitude of tDCS on pain score decreases.”
Reference
Brietzke AP, Zortea M, Carvalho F, et al. Large treatment effect with extended home-based transcranial direct current stimulation over dorsolateral prefrontal cortex in fibromyalgia: a proof of concept sham-randomized clinical study [published online July 26, 2019]. J Pain. doi:10.1016/j.jpain.2019.06.013
