Stochastic galvanic vestibular stimulation produces a small reduction in sway in Parkinson's disease

We investigated the effects of bicathodal stochastic galvanic vestibular stimulation (GVS) on body sway in normal subjects and in Parkinson's Disease (PD) patients. Twenty normal subjects and five PD patients were stimulated with four stimulus intensities between 0 and 0.5 mA and sway was measured in two stance conditions (on a compliant surface with either eyes open (EOCS) or closed (ECCS)). Subjects stood facing forward with their feet together on a force platform. Centre of pressure (CoP) displacement over 26 seconds was measured in the anteroposterior (AP) and mediolateral (ML) planes. GVS had no significant overall effect on sway in the normal subjects. In the patients a small (4.5%) significant decrease in sway was seen in the ECCS condition with low intensity (0.1 mA) stimulation (P = 0.02). Similar changes were seen in the normal subjects. This work indicates that low intensities of stochastic GVS can reduce sway levels in PD patients for certain stance conditions.