Table 2.

tDCS studies for therapeutic purpose

References	Patient group	Study design	Intervention	Target of the stimulation	Effect
Buttkus et al. [26]	10 MD (guitarists)	Double-blinded randomized with cross-over	Single session of cathodal tDCS (2 mA for 20 min) vs. placebo	Left M1	No change in fine motor control after 30 min
Benninger et al. [24]	12 WC	Double-blinded randomized, sham-controlled with parallel	Prolonged sessions (3 in 1 week) of cathodal tDCS	M1 contralateral to FHD	No positive effects in clinical measures nor handwriting and cortical excitability
Buttkus et al. [25]	9 MD (pianists)	Double-blinded sham-controlled with cross-over	Anodal tDCS, cathodal tDCS (2 mA for 20 min) during sensorimotor retraining	Left M1	No favorable result in behavior
Furuya et al. [27]	10 MD, 10 healthy musicians (pianists)	Double-blinded sham-controlled with cross-over	tDCS (2 mA for 24 min) during bimanual mirrored finger movements	Bihemispheric motor cortices	Improved rhythmic accuracy of sequential finger movements with cathodal-affected and anodal-unaffected tDCS
Sadnicka et al. [29]	10 WC	Single-blinded sham-controlled with cross-over	Single session anodal tDCS (sham-controlled)	Cerebellum	No changes in clinical symptoms nor in M1 plasticity
Bradnam et al. [28]	8 FHD (5 WC, 3 MD) and 8 HV	Double-blinded randomized sham-controlled with cross-over	Anodal, cathodal (2 mA, 20 min) or sham tDCS	Cerebellum	Improved writing kinematics and decreased CBI with anodal tDCS
Rosset-Llobet et al. [30]	30 MD	Parallel double-blind randomized design	tDCS (real vs. sham) for 30 min coupled with 1 hr sensory motor retuning therapy for 2 weeks (10 days)	Cathode over left and anode over right parietal regions	Improved dystonia severity score in both groups; more benefit in real tDCS than sham group

tDCS: transcranial direct current stimulation, MD: musician’s dystonia, WC: writer’s cramp, HV: healthy volunteer, FHD: focal hand dystonia, CBI: cerebellar inhibition, M1: motor cortex.