Non-invasive brain stimulation in fibromyalgia
Fibromyalgia (FM) is a disorder characterized by widespread musculoskeletal pain accompanied by fatigue, sleep, memory and mood issues. Symptoms sometimes begin after a physical trauma, surgery, infection or significant psychological stress. Brain stimulation therapies can treat mental disorders by activating or inhibiting the brain with electricity.
The electricity can be given directly by electrodes implanted in the brain, or non-invasively through electrodes placed on the scalp. The effects of non-invasive brain stimulation (NBS), including repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (TDCS), in treating FM remain inconclusive. A study was performed with the aim to investigate present evidence of using NBS as an add-on treatment in treating FM.
From the database search of the Medline, Embase, PsycINFO and Cochrane Library electronic databases, from inception to July 2015, a trial was conducted to analyze randomized controlled trials of NBS in treating FM. A total of 16 studies were included in the current meta-analysis.
After the analysis, pooled mean effect sizes of the 16 included studies revealed significant favorable effects of NBS. The weighted mean effect size in reducing pain, depression, fatigue, sleep disturbance and tender points and improving general health/function were 0.667 (95% CI 0.446, 0.889), 0.322 (95% CI 0.140, 0.504), 0.511 (95% CI 0.247, 0.774), 0.682 (95% CI 0.350, 1.014), 0.867 (95% CI 0.310, 1.425) and 0.473 (95% CI 0.285, 0.661), respectively. rTMS stimulation yielded a greater effect size compared with that of TDCS (effect size 0.698 and 0.568, respectively; P < 0.0001). The primary motor cortex (M1) stimulation yielded a subtle greater effect size in pain reduction compared with that of the dorsolateral prefrontal cortex (effect size 0.709 and 0.693, respectively; P < 0.0001). No linear relationships were found between the effect sizes and treatment regimens and dose. Most of reported adverse effects were minor.
From the observations, it was noted that Both rTMS and TDCS might be feasible and safe modalities for treating FM. The general effects of rTMS and TDCS were compatible in FM patients. M1 stimulation has proven to be a better option in pain reduction and the dorsolateral prefrontal cortex might be better in depression improvement.