Transcranial direct current stimulation (tDCS) has the potential to improve upper limb motor outcomes after stroke. According to the assumption of interhemispheric inhibition, excessive inhibition from the motor cortex of the unaffected hemisphere to the motor cortex of the affected hemisphere may worsen upper limb motor recovery after stroke. We evaluated the effects of active cathodal tDCS of the primary motor cortex of the unaffected hemisphere (ctDCSM1UH) compared to sham, in subjects within 72 hours to 6 weeks post ischemic stroke. Cathodal tDCS was intended to inhibit the motor cortex of the unaffected hemisphere and hence decrease the inhibition from the unaffected to the affected hemisphere and enhance motor recovery. We hypothesized that motor recovery would be greater in the active than in the sham group. In addition, greater motor recovery in the active group might be associated with bigger improvements in measures in activity and participation in the active than in the sham group. We also explored, for the first time, changes in cognition and sleep after ctDCSM1UH. Thirty subjects were randomized to six sessions of either active or sham ctDCSM1UH as add-on interventions to rehabilitation. The NIH Stroke Scale (NIHSS), Fugl-Meyer Assessment of Motor Recovery after Stroke (FMA), Barthel Index (BI), Stroke Impact Scale (SIS), and Montreal Cognitive Assessment (MoCA) were assessed before, after treatment, and three months later. In the intent-to-treat (ITT) analysis, there were significant GROUP*TIME interactions reflecting stronger gains in the sham group for scores in NIHSS, FMA, BI, MoCA, and four SIS domains. At three months post intervention, the sham group improved significantly compared to posttreatment in FMA, NIHSS, BI, and three SIS domains while no significant changes occurred in the active group. Also at three months, NIHSS improved significantly in the sham group and worsened significantly in the active group. FMA scores at baseline were higher in the active than in the sham group. After adjustment of analysis according to baseline scores, the between-group differences in FMA changes were no longer statistically significant. Finally, none of the between-group differences in changes in outcomes after treatment were considered clinically relevant. In conclusion, active CtDCSM1UH did not have beneficial effects, compared to sham. These results were consistent with other studies that applied comparable tDCS intensities/current densities or treated subjects with severe upper limb motor impairments during the first weeks post stroke. Dose-finding studies early after stroke are necessary before planning larger clinical trials.
Introduction: Transcranial direct current stimulation (tDCS) has the potential to improve upper limb motor outcomes after stroke. Objective: To evaluate the safety and preliminary efficacy of active cathodal compared to sham tDCS of the primary motor cortex of the unaffected hemisphere (ctDCSM1 UH ), within 72 hours to 6 weeks post-ischemic stroke. Methods: In this randomized, double-blind study, 30 patients with unilateral hand paresis were assigned to either active or sham ctDCSM1 UH as add-on interventions to rehabilitation. The primary outcome was the frequency of adverse events. Secondary outcomes, compared before, immediately after treatment and three months later, included measures of upper limb motor performance and quality of life. Stroke volume was assessed before and after treatment. Results: Overall, tDCS was well tolerated and there were no serious adverse events. One subject in the active group reported paresthesias in the paretic arm during the first session of ctDCSM1 UH . Heart rate increased significantly after active and decreased significantly after sham ctDCSM1 UH but these changes were not clinically significant. Upper limb motor impairment and quality of life improved significantly more in the sham than in the active group at three months post-treatment according to intention-to-treat and per-protocol analyses. The between-group difference in motor impairment was not clinically relevant. There were no recurrent strokes and lesion volumes did not increase significantly in either group. Conclusions: Active ctDCSM1 UH was safe and well tolerated but the preliminary efficacy results do not support a beneficial role of this intervention within the first six weeks after stroke.
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