Acute effect of transcranial direct current stimulation on gait kinematics in individuals with Parkinson's disease

Abstract

Introduction: From the limitations of activities caused by Parkinson's disease (PD), gait impairments are considered as the most disabling. PD gait is typical, with feasting characteristics and freezing episodes. Due to gait changes together with postural instability and decreased mobility, patients are at large fall risk. Recently, non-invasive brain stimulation techniques have been introduced as a therapeutic tool for coping with PD such as transcranial direct current (tDCS) stimulation. This consists of the application of a constant current of low intensity. However, the effects of tDCS on motor losses such as gait in PD have not yet been fully established. Objective: The objective of this study is to verify if the anodal tDCS modifies the kinematic gait variables in individuals with PD after a single stimulation session. Methods: Twenty one individuals with PD underwent 10 sessions of conventional physiotherapy to homogenize the level of physical activity of the sample. They were then evaluated through the kinematics and the Unified Parkinson's Disease Rating Scale - Part III (UPDRS - III). Then, they received a single anodal tDCS session in which the anodal electrode was allocated 1.8 cm ahead of Cz in the area of the supplementary motor area (AMS) and the cathode electrode was placed in the supraorbital region of the most affected side (reported by the individual). Immediately after, they were reevaluated with the same instruments. Results: Four patients were excluded from the analyzes. Thus, the results are related to 8 patients in the real tDCS group and 9 in the sham tDCS group. The gait data are relative to the right leg. There was a statistical difference between the groups for gait cadence (t = 2,627, p = 0.007, d = -1.60) and for the variable number of strides (t = -3.095, p = 0.018, d = 1.40) when comparing real tDCS with sham tDCS groups. There was also a large effect size for these variables. For all others, there were no
statistical differences. Conclusion: The findings of this study suggest that anodal tDCS administered in a single session may improve kinematic gait variables in PD.