The effect of optokinetic and galvanic vestibular stimulations in reducing post-stroke postural asymmetry

To investigate the postural effect of 2 types of sensory stimulation in patients with a left hemispheric lesion (LHL) or right hemispheric lesion (RHL) compared with controls.

35 patients (18 LHL, 17 RHL) and 27 controls (mean age 54.1 years), with a mean delay post-stroke of 3.0 months were enrolled. Subjects stood on a force platform and were stimulated on the left and right side by optokinetic (Okn) and galvanic vestibular (Gv) stimulation. Lateral displacement following stimulation toward the right and left directions was calculated as the mean position of the centre of pressure (CP) during the stimulation period minus the mean position at rest.

Postural asymmetry was reduced in LHL and RHL patients. CP displacement was higher in cases of left-sided stimulation in the RHL group compared with control subjects and LHL patients (respectively 2.8 and 2.4 times higher, group effect, p<0.001, group × direction of stimulation interaction, p=0.007). The magnitude of displacement under Okn significantly correlated with Gv in all cases (ρ=0.635, p<0.001).

Both GV and Okn stimulations can modulate hemiparetic's CP and their postural effects are correlated.

Results support a high level cortical postural effect of sensory stimulation on supramodal spatial network.