Usefulness root mean square (RMS) analysis using wearable sensors for assessing balance in neurodegenerative disorders

Abstract

Postural instability is a common cause of sudden falls and fall-related injuries in patients with neurodegenerative diseases. Recently, using wearable sensors for assessing balance become alternative method for giving us objective and sensitive values. This study applied to 18 patients with sporadic adult-onset cerebellar ataxia (SAOA), 15 patients with Parkinson’s disease (PD), and 9 healthy controls. All participants were instructed to maintain an upright standing position in front of white wall, with performing visual conditions (eyes-open/close) and foot conditions (foot-open/close). To measure postural stability, we used a tri-axial gyro-based motion sensors attached to participant’s upper body. The mean distance reflecting the magnitude of AP (x) and ML (y) sway was analyzed by repeated measures ANOVA. Comparing with healthy control, patients with SAOA showed a larger mean distance. In Root Mean Square of Velocity (RMS) analysis, there was also a significant difference between 3 groups. As a result of Post-Hoc test, there was a significant difference between SAOA and PD group, and between SAOA and control group, however, there was no difference between PD and control group. In RMS acceleration analysis, three groups showed statistically significant differences. In detail, there were significant differences between SAOA and PD group, SAOA and control groups, but not between PD and control group. RMS and RMS acceleration showed disease specific characteristics. Our study shows not only usefulness as assessment tool but also evidence that has disease specific postural control system in neurodegenerative disease.