Department of Neurology, University of Minnesota, 516 Delaware Street SE, Minneapolis, MN, 55455, United States.
Department of Neurology, University of Minnesota, 516 Delaware Street SE, Minneapolis, MN, 55455, United States.
Gait Posture. 2021 Feb;84:205-208. doi: 10.1016/j.gaitpost.2020.12.012. Epub 2020 Dec 24.
Assessing postural stability in Parkinson's disease (PD) often relies on measuring the stepping response to an imposed postural perturbation. The standard clinical technique relies on a brisk backwards pull at the shoulders by the examiner and judgement by a trained rater. In research settings, various quantitative measures and perturbation directions have been tested, but it is unclear which metrics and perturbation direction differ most between people with PD and controls.
(1) Use standardized forward vs. backward perturbations of a support surface to evaluate reactive stepping performance between PD and control participants. (2) Evaluate the utility of using principal components analysis to capture the dynamics of the reactive response and differences between groups.
Sixty-two individuals participated (40 mild-to-moderate PD, off medication). Standardized rapid translations of the support surface were applied, requiring at least one step, backward or forward, to restore balance. The number of steps taken and the projection of the first principal component (PC1) of the center of pressure (COP) time series were entered in linear repeated-measures mixed effect models.
Forward falls required significantly fewer steps to recover than backward falls. PC1 captured more than half of the variance in the COP trajectory. Analysis of the PC1 projection revealed a significant interaction effect of group (PD vs. controls) by direction, such that there was a group difference in forward stepping, but not backward.
Forward reactive stepping in PD differed from controls more than backward-stepping. PC1 projections of the COP trajectory capture the dynamics of the postural response and differ between PD and controls.
在帕金森病（PD）中评估姿势稳定性通常依赖于测量对施加的姿势扰动的跨步反应。标准的临床技术依赖于检查者对肩部的快速向后拉，并由受过训练的评估者进行判断。在研究环境中，已经测试了各种定量测量和扰动方向，但尚不清楚 PD 患者和对照组之间哪些指标和扰动方向差异最大。
（1）使用标准化的支持面前后扰动来评估 PD 和对照组参与者的反应性跨步性能。（2）评估使用主成分分析来捕捉反应性响应的动态和组间差异的效用。
共有 62 人参与（40 名轻度至中度 PD，停药）。支持面的标准化快速平移应用，要求至少向后或向前迈出一步以恢复平衡。所采取的步数和压力中心（COP）时间序列的第一主成分（PC1）的投影被输入线性重复测量混合效应模型。
向前跌倒需要的恢复步数明显少于向后跌倒。PC1 捕获了 COP 轨迹的一半以上的方差。COP 轨迹的 PC1 投影分析显示了组（PD 与对照组）与方向的显著交互作用，即 PD 患者在向前跨步方面存在差异，但向后跨步方面没有差异。
PD 患者的向前反应性跨步与对照组的差异大于向后跨步。COP 轨迹的 PC1 投影捕获了姿势反应的动态，并在 PD 和对照组之间存在差异。
