A NEW TRUNK SWAY ASSESSMENT PROTOCOL FOR STROKE PATIENTS USING A BIOFEEDBACK INERTIAL-BASED SENSING MODALITY
Brain damage pathology can generate an irrelevant motor program leading to abnormal posture. Given this observation, we tested the hypothesis that postural control deficits are present in individuals with postural disorders. A new trunk sway assessment protocol evaluation system using an inertial-based sensing technique combined with visual-biofeedback strategies was developed. The proposed system was used to assess the angular deviation of the center of mass and enhanced balance control in patients with stroke. Twelve participants with hemiplegia were randomly divided into a visual-biofeedback group (experimental) and a without visual-biofeedback group (control), and were asked to stand as still as possible for 30 s. Postural sway data were submitted to conventional quantitative analyses of sway magnitude using a center of mass measurement. Additionally, group means were compared using parametric tests. Parameters in both the anterior-posterior and medio-lateral directions within the stroke patients were compared using paired t-tests. The experimental group showed increased postural control, indicative of reduced postural sway. Decreased complexity in the medio-lateral direction was also observed in the experimental group, suggesting both a reduction in the dynamic range available for postural control, and that their postural corrections were dominated primarily by longer-term scales. Significant interactions between the diagnostic group and visual condition were also observed for both of these measures, suggesting that the control group participants were impaired in their ability to make corrections to their sway pattern when no visual biofeedback was available. Greater sway magnitude and reduced complexity suggest that individuals with hemiplegia have deficits in sensorimotor integration and a reduced range of timescales available within which to make postural corrections.