How Additional Visual Feedback of the Movements Between Center of Pressure and Vertically Projected Center of Gravity Can Be Used by Hemiparetic Patients

Abstract

Purpose: In healthy adults, the beneficial effect of providing additional visual feedback (VFB) with a delay of either the center of pressure (CP) or the difference between CP movements and center of gravity (CP−CG_v) movements was previously demonstrated and explained by their capacity to decrease their CP-CG_v movements. The present study seeks to demonstrate whether similar trends could be observed in hemiparetic patients. Methods: Posturographic measurements were recorded in 56 hemiparetic patients in 3 VFB conditions: (1) CP in real time (VFB_CP0), (2) CP with a 600-ms delay (VFB_CP600), and (3) CP−CG_v with a 600-ms delay (VFB_CP-CG600). A condition without VFB (eyes open [EO]) was also included. The individual capacity to lower CP−CG_v movements as compared to the reference VFB_CP0 condition was assessed using dependency coefficients (ie, average surface covered by the CP−CG_v displacements in an experimental condition relative to the VFB_CP0 condition) in the VFB_CP600, VFB_CP-CG600, and EO conditions. Results: Reduced CP−CG_v movements were only obtained for half of the patients for the conditions with delay or without VFB. Significant linear correlations revealed that the most successful patients are characterized by reduced CP−CG_v movements in these conditions and in the EO condition. In contrast, a poor correlation was found with the patients’ clinical scores. Conclusion: Based on the behavioral profile of a patient able to use these VFB techniques effectively, this study emphasizes the complementary nature of the various conditions proposed by the VFB technique and provides insights for establishing rehabilitation protocols based on this VFB technique.

Keywords:

• center of gravity
• center of pressure
• hemiparesis
• rehabilitation
• postural control
• visual feedback