A group of European experts was commissioned by the European Chapter of the International
Federation of Clinical Neurophysiology to gather knowledge about the state of the
art of the therapeutic use of transcranial direct current stimulation (tDCS) from
studies published up until September 2016, regarding pain, Parkinson's disease, other
movement disorders, motor stroke, poststroke aphasia, multiple sclerosis, epilepsy,
consciousness disorders, Alzheimer's disease, tinnitus, depression, schizophrenia,
and craving/addiction. The evidence-based analysis included only studies based on
repeated tDCS sessions with sham tDCS control procedure; 25 patients or more having
received active treatment was required for Class I, while a lower number of 10-24
patients was accepted for Class II studies. Current evidence does not allow making
any recommendation of Level A (definite efficacy) for any indication. Level B recommendation
(probable efficacy) is proposed for: (i) anodal tDCS of the left primary motor cortex
(M1) (with right orbitofrontal cathode) in fibromyalgia; (ii) anodal tDCS of the left
dorsolateral prefrontal cortex (DLPFC) (with right orbitofrontal cathode) in major
depressive episode without drug resistance; (iii) anodal tDCS of the right DLPFC (with
left DLPFC cathode) in addiction/craving. Level C recommendation (possible efficacy)
is proposed for anodal tDCS of the left M1 (or contralateral to pain side, with right
orbitofrontal cathode) in chronic lower limb neuropathic pain secondary to spinal
cord lesion. Conversely, Level B recommendation (probable inefficacy) is conferred
on the absence of clinical effects of: (i) anodal tDCS of the left temporal cortex
(with right orbitofrontal cathode) in tinnitus; (ii) anodal tDCS of the left DLPFC
(with right orbitofrontal cathode) in drug-resistant major depressive episode. It
remains to be clarified whether the probable or possible therapeutic effects of tDCS
are clinically meaningful and how to optimally perform tDCS in a therapeutic setting.
In addition, the easy management and low cost of tDCS devices allow at home use by
the patient, but this might raise ethical and legal concerns with regard to potential
misuse or overuse. We must be careful to avoid inappropriate applications of this
technique by ensuring rigorous training of the professionals and education of the
patients.