Speers R A, Shepard N T, Kuo A D
Vestibular Testing Center, Dept. of Otolaryngology, University of Michigan, Ann Arbor 48109-0816, USA.
J Vestib Res. 1999;9(6):435-44.
The Sensory Organization Test protocol of the EquiTest system (NeuroCom International, Clackamas Oregon) tests utilization of visual, vestibular, and proprioceptive sensors by manipulating the accuracy of visual and/or somatosensory inputs during quiet stance. In the standard Sensory Organization Test, both manipulation of sensory input (sway-referencing) and assessment of postural sway are based on ground reaction forces measured from a forceplate. The purpose of our investigation was to examine the use of kinematic measurements to provide a more direct feedback signal for sway-referencing and for assessment of sway. We compared three methods of sway-referencing: the standard EquiTest method based on ground reaction torque, kinematic feedback based on servo-controlling to shank motion, and a more complex kinematic feedback based on servo-controlling to follow position of the center of mass (COM) as calculated from a two-link biomechanical model. Fifty-one normal subjects (ages 20-79) performed the randomized protocol. When using either shank or COM angle for sway-referencing feedback as compared to the standard EquiTest protocol, the Equilibrium Quotient and Strategy Score assessments were decreased for all age groups in the platform sway-referenced conditions (SOT 4, 5, 6). For all groups of subjects, there were significant differences in one or more of the kinematic sway measures of shank, hip, or COM angle when using either of the alternative sway-referencing parameters as compared to the standard EquiTest protocol. The increased sensitivities arising from use of kinematics had the effect of amplifying differences with age. For sway-referencing, the direct kinematic feedback may enhance ability to reduce proprioceptive information by servo-controlling more closely to actual ankle motion. For assessment, kinematics measurements can potentially increase sensitivity for detection of balance disorders, because it may be possible to discriminate between body sway and acceleration and to determine the phase relationship between ankle and hip motion.
EquiTest系统（NeuroCom International，俄勒冈州克拉卡马斯）的感觉组织测试方案，通过在安静站立时操纵视觉和/或体感输入的准确性，来测试视觉、前庭和本体感觉传感器的利用情况。在标准感觉组织测试中，感觉输入的操纵（摆动参考）和姿势摆动的评估均基于从测力板测量的地面反作用力。我们研究的目的是检验运动学测量的应用，以便为摆动参考和摆动评估提供更直接的反馈信号。我们比较了三种摆动参考方法：基于地面反作用扭矩的标准EquiTest方法、基于对小腿运动进行伺服控制的运动学反馈，以及基于对由双连杆生物力学模型计算出的质心（COM）位置进行伺服控制的更复杂运动学反馈。51名正常受试者（年龄20 - 79岁）执行了随机方案。与标准EquiTest方案相比，当使用小腿或COM角度进行摆动参考反馈时，在平台摆动参考条件下（感觉组织测试4、5、6），所有年龄组的平衡商和策略得分评估均降低。对于所有受试者组，与标准EquiTest方案相比，当使用任何一种替代摆动参考参数时，小腿、髋部或COM角度的一种或多种运动学摆动测量存在显著差异。使用运动学所产生的更高敏感性具有放大年龄差异的作用。对于摆动参考，直接运动学反馈可能通过更紧密地伺服控制实际踝关节运动来增强减少本体感觉信息的能力。对于评估，运动学测量可能会提高检测平衡障碍的敏感性，因为有可能区分身体摆动和加速度，并确定踝关节和髋关节运动之间的相位关系。
