Transcranial direct current stimulation for the treatment of fibromyalgia: a systematic review

Introduction. Fibromyalgia is a multisymptomatic diffuse chronic musculoskeletal pain syndrome with evidence of central nervous system dysfunction. Accordingly, non-invasive brain stimulation techniques such as transcranial direct current stimulation (tDCS) may be a complementary therapeutic resource to reduce pain perception. Aims. To review the potential effectiveness of tDCS to reduce pain in fibromyalgia, to identify the most effective neurostimulation parameters and to delimit its safety. Patients and methods. Systematic review of prospective studies reported in PubMed and Cochrane reviews. Results. The anodal tDCS of the left primary motor cortex, at 2mA for 20 minutes with 35 cm(2) electrodes on five consecutive days, provides better results in reducing pain (14-59%), and improving sleep quality, with greater accentuation on the fifth day. The clinical improvement persists up to a minimum of 60 days (11-20% reduction of pain). Adverse effects are well tolerated and few. Conclusions. The experience with tDCS in fibromyalgia is still limited. However, the anodal tDCS in the left primary motor cortex can be recommended with level B (probable therapeutic efficacy) and appears to act through the modification of the sensorial processing of the pain of thalamic inhibitory circuitry.