Department of Biomedical Engineering, Oregon Health & Science University Portland, OR, USA.
Front Neurol. 2011 Sep 6;2:57. doi: 10.3389/fneur.2011.00057. eCollection 2011.
Postural control of upright stance was investigated in well-compensated, unilateral vestibular loss (UVL) subjects compared to age-matched control subjects. The goal was to determine how sensory weighting for postural control in UVL subjects differed from control subjects, and how sensory weighting related to UVL subjects' functional compensation, as assessed by standardized balance and dizziness questionnaires. Postural control mechanisms were identified using a model-based interpretation of medial-lateral center-of-mass body-sway evoked by support-surface rotational stimuli during eyes-closed stance. The surface-tilt stimuli consisted of continuous pseudorandom rotations presented at four different amplitudes. Parameters of a feedback control model were obtained that accounted for each subject's sway response to the surface-tilt stimuli. Sensory weighting factors quantified the relative contributions to stance control of vestibular sensory information, signaling body-sway relative to earth-vertical, and proprioceptive information, signaling body-sway relative to the surface. Results showed that UVL subjects made significantly greater use of proprioceptive, and therefore less use of vestibular, orientation information on all tests. There was relatively little overlap in the distributions of sensory weights measured in UVL and control subjects, although UVL subjects varied widely in the amount they could use their remaining vestibular function. Increased reliance on proprioceptive information by UVL subjects was associated with their balance being more disturbed by the surface-tilt perturbations than control subjects, thus indicating a deficiency of balance control even in well-compensated UVL subjects. Furthermore, there was some tendency for UVL subjects who were less able to utilize remaining vestibular information to also indicate worse functional compensation on questionnaires.
我们研究了姿势控制在单侧前庭功能丧失（UVL）患者和年龄匹配的对照组中的表现。目的是确定在 UVL 患者中，姿势控制的感觉权重与对照组有何不同，以及感觉权重与 UVL 患者的功能补偿之间的关系，通过标准化的平衡和头晕问卷进行评估。使用基于模型的解释方法，对闭眼站立时支撑面旋转刺激引起的身体中重心侧向摆动进行分析，从而确定姿势控制机制。表面倾斜刺激由连续的伪随机旋转组成，在四个不同的振幅下呈现。获取反馈控制模型的参数，以解释每个受试者对表面倾斜刺激的摆动反应。感觉权重因素量化了前庭感觉信息对站立控制的相对贡献，该信息表示身体相对于地球垂直方向的摆动，以及本体感觉信息，该信息表示身体相对于表面的摆动。结果表明，在所有测试中，UVL 患者对本体感觉的依赖性更大，对前庭定向信息的依赖性更小。尽管 UVL 患者在其剩余前庭功能的利用程度上差异很大，但在测量的感觉权重分布中，UVL 患者和对照组之间相对较少重叠。UVL 患者对本体感觉信息的依赖性增加，表明他们的平衡受到表面倾斜扰动的干扰比对照组更大，这表明即使在补偿良好的 UVL 患者中，平衡控制也存在缺陷。此外，那些不能很好地利用剩余前庭信息的 UVL 患者，在问卷上也表现出较差的功能补偿。
