Fibromyalgia is a chronic pain syndrome affecting the musculoskeletal system with unknown causes. Disease symptoms include diffusive pain, fatigue, and emotional distress. An accumulating amount of evidences suggest that non-invasive brain electric stimulation techniques targeting the primary motor cortex have significant analgesic effects in fibromyalgia by modifying the pain sensory process. However, results of clinical studies using these techniques are inconsistent, mainly due the lack of optimized standard protocols and trial design.
In a recent study, a team of researchers from the U.S. and Israel defined procedures for effective fibromyalgia pain treatment with High-Definition transcranial Direct Current Stimulation (HD-tDCS), establishing clinical protocols and optimal stimulation parameters. This methodology was described in a paper entitled “Clinically effective treatment of fibromyalgia pain with HD-tDCS – Phase II open-label dose-optimization,” published in The Journal of Pain.
The HD-tDCS technique allows for a non-invasive focused application of a low intensity direct current, enhancing and sustaining its pain reducing effects. Researchers used a visual analog scale and measurements of brain responses to assess the pain of 14 fibromyalgia patients treated with HD-tDCS for a maximum of six weeks. Their main goal was to define the mean number of sessions, defined as a 50% decrease in pain, and the optimal stimulation parameters required to achieve a clinical meaningful response with limited side effects.
Half of the participants reported that treatment resulted in a 50% pain reduction and both responders and non-responders showed increased pain relief levels and quality of life over time. Based on the results, the team estimated that a median of 15 HD-tDCS sessions with a 2 mA delivery current over the course of three weeks are required for an effective clinical outcome. Side effects were mainly mild, transient, and did not increase with the number of sessions, being related with scalp tingling sensation, mild headache, minor pain, and skin redness.
It thus seems that the protocol for fibromyalgia pain treatment with HD-tDCS has the potential to develop into an effective real-life therapy. However, validation of these results is needed. This work evaluated a reduced fibromyalgia population and did not consider the effect of placebo responses, a critical parameter in fibromyalgia. Future studies will likely address these issues, and an effective HD-tDCS protocol to alleviate fibromyalgia pain might become available to patients.