Effects of visual feedback of center-of-pressure displacements on undisturbed upright postural control of hemiparetic stroke patients

Abstract

To assess whether insights from postural control without additional visual feedback (VFB) could be gained to explain the possible VFB effects (or non-effects) on upright stance performance. The center-of-pressure (CP) displacements of 39 patients with a recent hemispheric stroke (93 days ± 56; mean ± s.d.) were analyzed in two conditions (eyes open and VFB) through various classical parameters and fractional Brownian motion (fBm) modeling. Correlations between their ability to use the VFB technique appropriately and parameters assessing the eyes open condition were also computed. The fBm modeling showed that the VFB technique improves the control of the CP trajectories over the longer time intervals. In both conditions, the patients with right hemiparesis, compared to those with left hemiparesis, demonstrated improved control of their CP displacement along the AP axis over the shortest time intervals. Overall, 28% of the patients did not use the VFB technique. The correlation analysis indicated that the larger the spontaneous CP movements in the eyes open condition, the greater the effect of the VFB technique. By emphasizing its particular effects and the profile of the patients who used the technique, these data specify the conditions allowing hemiparetic patients to use the VFB technique appropriately and immediately.