Objectives: Fibromyalgia is a type of chronic musculoskeletal pain without a clear peripheral origin of nociception, often associated with depression. The underlying pathophysiology involves changes in a functional network that is related to pain and emotional processing in the central nervous system. Transcranial direct current stimulation (tDCS) targeting the dorsolateral prefrontal cortex or the occipital nerve (ON) are non-invasive neuromodulation techniques capable of improving fibromyalgia symptoms. This study aims to test the effect of combining two targets of stimulation using tDCS.
Methods: We applied ON-tDCS in isolation or coupled with pre-ONS right-anode bifrontal tDCS, and assessed its effect on fibromyalgia using the Fibromyalgia Impact Questionnaire, the Beck depression inventory, and Numeric Rating Scale for pain scores. These measures were compared to a sham control group using repeated measures ANOVA.
Results: The interaction effect of stimulation trials and the protocols of sham versus ON-tDCS was significant for the impact, distress, and pain caused by fibromyalgia (P <0.05). The interaction effect of trials and protocols of sham versus ON-tDCS with bifrontal tDCS was significant for the distress (P <0.01), and showed a trend of improvement for the impact and the pain (P <0.1). Based on the non-significant interaction effect of ON-tDCS versus ON-tDCS with bifrontal tDCS (P >0.1), adding bifrontal tDCS was found not to improve the treatment effect of ON-tDCS in any of the tested clinical outcome measures.
Discussion: This study suggests that adding right-anode bifrontal tDCS to ONS has no added benefit in improving fibromyalgia related symptoms.
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