Effects of Galvanic Vestibular Stimulation on Subjective Visual Vertical and Sitting Balance in Patients with Stroke

This study aimed to examine the effects of galvanic vestibular stimulation (GVS) on visual vertical cognition and sitting balance in stroke patients.Patients with unilateral supratentorial infarction and hemorrhagic lesions and healthy controls were recruited. Bipolar GVS was performed through the bilateral mastoid processes with an 1.5-mA electric current. Each participant received three stimulation patterns: right anode-left cathode, left anode-right cathode, and sham. The subjective visual vertical (SVV) and center of gravity positions in the sitting posture were measured in three groups of participants: patients with right hemisphere lesions, patients with left hemisphere lesions, and in healthy controls. Changes in the SVV and center of gravity positions before and during galvanic vestibular stimulation were assessed.In each group, eight individuals were recruited for SVV measurements and nine individuals for center of gravity measurements. We found changes due to polarity of stimulation on the SVV and mediolateral changes in the center of gravity in the sitting position of patients with stroke, while there was no significant difference between groups or interaction of the two factors (polarity vs. group).Changes in the visual vertical cognition and sitting balance occur during GVS in patients with stroke. GVS is a potential tool for ameliorating balance dysfunction in patients with stroke.