Anodal tDCS increases corticospinal output and projection strength in multiple sclerosis

The application of anodal transcranial direct current stimulation (atDCS) to the human brain has been shown to elicit corticospinal (CS) excitability changes. This study evaluated the effect of a single session of atDCS on CS excitability in patients with multiple sclerosis (MS). atDCS and sham tDCS (stDCS) were applied to the primary motor cortex (M1) contralateral to the more severely impaired hand for 20 min in a double-blinded crossover design. Changes in CS excitability were assessed using transcranial magnetic stimulation (TMS). The area under the recruitment curves increased significantly after application of atDCS (+56.58%, p = 0.023) but not after stDCS. A sigmoidal curve-analysis revealed a higher plateau of the curve after atDCS (+22.2%, p < 0.001). Our results showed that atDCS over M1 has the ability to increase CS output and projection strength in MS-patients, suggesting that atDCS can be considered during neural rehabilitation to facilitate motor recovery in MS.