Table 2 Characteristics of intervention used in included trials (n = 6)

Dehem et al. [39]

20 min of real dual-tDCS (at 1 mA) along with RAT

20 min of sham dual-tDCS along with RAT

Two sessions 7 days apart, each session lasted for 20 min

BBT (P = 0.008) and straightness during free amplitude task (P = 0.019) were significantly better after receiving real tDCS + RAT

Other kinematics and fine manual dexterity were not significantly improved after real tDCS + RAT (P > 0.05)

Edwards et al. [40] 

RT plus tDCS − 2 mA current for 20 min

RT plus sham tDCS

3 sessions per week (RT = ~ 1 h, tDCS = 20 min), for 12 weeks

FM-UE score and Wolf Motor Function Test improved significantly

Mazzoleni wt al. [3]

Wrist RAT + real tDCS anodic stimulation of 2 mA

Wrist RAT + sham tDCS with initial activation ramp (t = 5 s)

Five sessions per week, each session lasted 30 min, for 6 weeks

Significant improvements in the FM/ue, FM/w, MI and B&B in both groups

MAS/w: slightly decrease in both groups, no significant difference between groups

Mazzoleni et al. [41]

Real tDCS − 2 mA for 20 min along with wrist RT

Sham tDCS (5 s) along with wrist RT

Five sessions per week, each session lasted 30 min, for 6 weeks

All clinical outcome measures, except the MAS/w, showed a significant increase after treatment

No significant difference in the average changes after the treatment between the EG and the CG was observed

Straudi et al. [36]

30 min of real tdcs (at 1 mA) + 30 min of RAT

30 min of sham TDCS (first 30 s current delivered) + 30 min of RAT

Five sessions/week over 2 weeks (10 sessions), each session lasted about 60 min (30 mnt tDCS + 30 mnt RAT)

Significant differences in FMA-UE in both groups

Scores of BBT and MAL were improved only in real-tDCS group

Triccas et al. [4]

Real tDCS − 1 mA for 20 min along with RT

Sham tDCS − 1 mA along with RT

2–3 sessions per week for 8 weeks, each session lasted for 1 h and 15 min

FM-UE improved in both groups

Similar effect was observed for the HPR, ARAT, MAL and SIS