Safety Review of Transcranial Direct Current Stimulation in Stroke

The safety, painless, and tolerability features of transcranial Direct Current Stimulation (tDCS) have prompted the research on the therapeutic effects of this technique in stroke; however, an in-depth and unarguable examination of the adverse effects of tDCS in stroke patients is still lacking. This review analyzes the reported adverse effects in stroke, looking for factors that may induce side-effects.

A comprehensive search of articles published from 1998 to 2015 describing tDCS application in stroke patients performed through data extraction from MEDLINE/PubMed database.

Only 11.62% of published papers reported the occurrence of tDCS adverse effects in stroke patients. The most common was itching (70%), followed by burning sensation (40%), headache (40%), tingling (30%), sleepiness (20%), difficulty of concentration, mild fatigue, skin redness, and dizziness (10%). No significant difference was found between studies "Reporting" vs. "Non-reporting" adverse effects regarding tDCS parameters (intensity, current density, duration of stimulation, and number of sessions).

In the majority of stroke patients, tDCS did not induce any severe adverse effect. Regrettably, many published papers did not provide a careful description of exclusion criteria, nor a systematic report of side effects. Our work emphasizes the need of a more meticulous description of the adopted exclusion criteria and of the induced adverse effects, in order to optimize the therapeutic use of tDCS and to better delineate its safety parameters in stroke.