Background

Impaired movement stability is a common symptom of Parkinson’s disease (PD) that leads to falls and mishandled objects. Decline in synergistic stabilization of movement in PD patients has been observed in manual and postural tasks. However, locomotor synergies have not been quantified in PD patients.

Research question

The purpose of this work was to quantify the strength of the synergy stabilizing the step length while crossing an obstacle in PD patients. We hypothesized that (1) the distances of the front and rear feet relative to the obstacle would display compensatory across-trial co-variance that stabilizes step length in PD patients and age-matched controls, and (2) the step-length stabilization would be weaker in PD patients.

Methods

Thirteen PD patients and eleven healthy age-matched controls walked up to and stepped over a 15 cm high obstacle fifteen times.We measured the distances of the rear and front foot toes from the obstacle during the crossing step. We used the uncontrolled manifold method to parse the across-trial variance in toe distances into a component that maintains the step length and a component that changes the step length. These variance components yielded the synergy index that quantified the stability of step length.

Results

Step length was stabilized in PD patients as well as controls. However, the synergy index was 53% lower in the PD patients (p < 0.01). Thus, both our hypotheses were supported.

Significance

This is the first study reporting impaired locomotor synergies in PD patients. Most PD patients in our sample were early stage (10 out of 13 patients were Hoehn-Yahr ≤ 2). Therefore, this result motivates further studies to establish step-length synergy during adaptive locomotor tasks as a biomarker for early detection of locomotor impairments in PD patients.

中文翻译：

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帕金森氏病患者越过障碍时的步长协同作用较弱

背景

运动稳定性受损是帕金森氏病（PD）的常见症状，会导致跌倒和处理不当的物体。在手动和姿势任务中观察到PD患者运动的协同稳定作用下降。然而，在PD患者中尚未量化运动协同作用。

研究问题

这项工作的目的是量化在PD患者中越过障碍时稳定步长的协同作用的强度。我们假设（1）前脚和后脚相对于障碍物的距离会显示出补偿性的跨试验协方差，可以稳定PD患者和年龄匹配的对照组的步长，（2）步长稳定在PD患者中较弱。

方法

13名PD患者和11名年龄匹配的健康对照者走过15厘米高的障碍物并走过15次。我们测量了交叉步中后脚趾和前脚趾与障碍物的距离。我们使用不受控制的流形方法将脚趾距离的跨试验方差解析为保持步长的组件和改变步长的组件。这些方差成分产生的协同指数量化了步长的稳定性。

结果

PD患者和对照组的步长均稳定。但是，PD患者的协同指数降低了53％（p <0.01）。因此，我们的两个假设都得到了支持。

意义

这是第一项报道PD患者运动协同作用受损的研究。我们样本中的大多数PD患者为早期阶段（13名患者中有10名Hoehn-Yahr≤2）。因此，该结果激发了进一步的研究，以在适应性运动任务期间建立步长协同作用，作为早期检测PD患者运动损伤的生物标记。