Combined central and peripheral stimulation to facilitate motor recovery after stroke: the effect of number of sessions on outcome.

Background. Proof-of-principle studies have demonstrated transient beneficial effects of transcranial direct current stimulation (tDCS) on motor function in stroke patients, mostly after single treatment sessions. Objective. To assess the efficacy of multiple treatment sessions on motor outcome. Methods. The authors examined the effects of two 5-day intervention periods of bihemispheric tDCS and simultaneous occupational/physical therapy on motor function in a group of 10 chronic stroke patients. Results. The first 5-day period yielded an increase in Upper-Extremity Fugl-Meyer (UE-FM) scores by 5.9 ± 2.4 points (16.6% ± 10.6%). The second 5-day period resulted in further meaningful, although significantly lower, gains with an additional improvement of 2.3 ± 1.4 points in UE-FM compared with the end of the first 5-day period (5.5% ± 4.2%). The overall mean change after the 2 periods was 8.2 ± 2.2 points (22.9% ± 11.4%). Conclusion. The results confirm the efficacy of bihemispheric tDCS in combination with peripheral sensorimotor stimulation. Furthermore, they demonstrate that the effects of multiple treatment sessions in chronic stroke patients may not necessarily lead to a linear response function, which is of relevance for the design of experimental neurorehabilitation trials.