Previous studies suggest that transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) reduces chronic pain levels. In this randomized controlled trial, we investigated the effects of 5 consecutive 20-minute sessions of 2-mA anodal tDCS directed to the M1 in 48 patients (45 females) with fibromyalgia. Changes in pain, stress, daily functioning, psychiatric symptoms, and health-related quality of life were measured. Pain and stress were measured 30 days before treatment, at each treatment, and 30 days after treatment by using short message service on mobile phones. Patients were randomized to the active or sham tDCS group by receiving individual treatment codes associated either with the sham or active tDCS in the stimulator. Adverse effects were registered using a standardized form. A small but significant improvement in pain was observed under the active tDCS condition but not under the sham condition. Fibromyalgia-related daily functioning improved in the active tDCS group compared with the sham group. The stimulation was well tolerated by the patients, and no significant difference in the adverse effects between the groups was observed. The results suggest that tDCS has the potential to induce statistically significant pain relief in patients with fibromyalgia, with no serious adverse effects, but small effect sizes indicate that the results are unlikely to reflect clinically important changes.
Five 20-minute sessions of anodal transcranial direct current stimulation on M1 reduced pain levels in patients with fibromyalgia. Stimulation was well tolerated by patients.
aDepartment of Surgery and Anesthesia, University Hospital of North Norway, Tromsø, Norway
bDepartment of Psychology, University of Tromsø, Tromsø, Norway
cDepartment of Physical Medicine and Rehabilitation, University Hospital of North Norway, Tromsø, Norway
dDivision of Child and Adolescent Health Services, Department of Child and Adolescent Psychiatry, University Hospital of North Norway, Tromsø, Norway
Corresponding author. Address: Department of Psychology, Faculty of Health Sciences, University of Tromsø, 9037 Tromsø, Norway. Tel.: +49 97604709; fax: +47 77645291. E-mail address: firstname.lastname@example.org (A. J. Fagerlund).
Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.
Received July 11, 2014
Received in revised form October 16, 2014
Accepted October 21, 2014