[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 cm2 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.