Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC, United States of America.
UNC Healthcare, UNC Center for Rehabilitation Care, Chapel Hill, NC, United States of America.
PLoS One. 2020 Mar 10;15(3):e0230202. doi: 10.1371/journal.pone.0230202. eCollection 2020.
People with multiple sclerosis (PwMS) who exhibit minimal to no disability are still over twice as likely to fall as the general population and many of these falls occur during walking. There is a need for more effective ways to detect preclinical walking balance deficits in PwMS. Therefore, the purpose of this study was to investigate the effects of optical flow perturbations applied using virtual reality on walking balance in PwMS compared to age-matched controls. We hypothesized that susceptibility to perturbations-especially those in the mediolateral direction-would be larger in PwMS compared to controls. Fourteen PwMS and fourteen age-matched controls walked on a treadmill while viewing a virtual hallway with and without optical flow perturbations in the mediolateral or anterior-posterior directions. We quantified foot placement kinematics, gait variability, lateral margin of stability and, in a separate session, performance on the standing sensory organization test (SOT). We found only modest differences between groups during normal, unperturbed walking. These differences were larger and more pervasive in the presence of mediolateral perturbations, evidenced by higher variability in step width, sacrum position, and margin of stability at heel-strike in PwMS than controls. PwMS also performed worse than controls on the SOT, and there was a modest correlation between step width variability during perturbed gait and SOT visual score. In conclusion, mediolateral optical flow perturbations revealed differences in walking balance in PwMS that went undetected during normal, unperturbed walking. Targeting this difference may be a promising approach to more effectively detect preclinical walking balance deficits in PwMS.
多发性硬化症患者（PwMS）表现出最小至无残疾的人仍然是一般人群的两倍以上，而且这些跌倒中有许多发生在行走过程中。因此，需要更有效的方法来检测 PwMS 临床前行走平衡缺陷。因此，本研究的目的是调查与年龄匹配的对照组相比，使用虚拟现实应用光流扰动对 PwMS 行走平衡的影响。我们假设 PwMS 对扰动的敏感性-特别是在横向方向上的敏感性-将比对照组更大。14 名 PwMS 和 14 名年龄匹配的对照组在跑步机上行走，同时观看虚拟走廊，走廊中存在或不存在横向或前后方向的光流扰动。我们量化了足部放置运动学、步态变异性、侧向稳定性边界，以及在单独的会议上，进行站立感觉组织测试（SOT）的表现。我们发现，在正常、未受干扰的行走中，两组之间仅存在适度差异。这些差异在存在横向扰动时更大且更普遍，表现为 PwMS 的步宽、骶骨位置和足跟冲击时稳定性边界的变异性高于对照组。PwMS 在 SOT 上的表现也比对照组差，并且在受干扰的步态期间步宽变异性与 SOT 视觉评分之间存在适度相关性。总之，横向光流扰动揭示了 PwMS 行走平衡中的差异，这些差异在正常、未受干扰的行走中无法检测到。针对这种差异可能是更有效地检测 PwMS 临床前行走平衡缺陷的有前途的方法。
