Department of Neurosciences, University of Montreal, Montreal, Quebec, Canada.
Department of Physical Therapy, Emory University, Atlanta, GA, USA; Exercise and Rehabilitation Sciences Laboratory, School of Physical Therapy, Faculty of Rehabilitation Sciences, Universidad Andres Bello, 7591538 Santiago, Chile.
Clin Neurophysiol. 2023 Oct;154:12-24. doi: 10.1016/j.clinph.2023.06.022. Epub 2023 Jul 17.
We investigated changes in indices of muscle synergies prior to gait initiation and the effects of gaze shift in patients with Parkinson's disease (PD). A long-term objective of the study is to develop a method for quantitative assessment of gait-initiation problems in PD.
PD patients without clinical signs of postural instability and two control groups (age-matched and young) performed a gait initiation task in a self-paced manner, with and without a quick prior gaze shift produced by turning the head. Muscle groups with parallel scaling of activation levels (muscle modes) were identified as factors in the muscle activation space. Synergy index stabilizing center of pressure trajectory in the anterior-posterior and medio-lateral directions (indices of stability) was quantified in the muscle mode space. A drop in the synergy index in preparation to gait initiation (anticipatory synergy adjustment, ASA) was quantified.
Compared to the control groups, PD patients showed significantly smaller synergy indices and ASA for both directions of the center of pressure shift. Both PD and age-matched controls, but not younger controls, showed detrimental effects of the prior gaze shift on the ASA indices.
PD patients without clinically significant posture or gait disorders show impaired stability of the center of pressure and its diminished adjustment during gait initiation.
The indices of stability and ASA may be useful to monitor pre-clinical gait disorders, and lower ASA may be relevant to emergence of freezing of gait in PD.
我们研究了帕金森病（PD）患者在开始行走前肌肉协同作用指标的变化以及眼球转移对视动的影响。该研究的长期目标是开发一种用于定量评估 PD 患者行走起始问题的方法。
无姿势不稳定临床症状的 PD 患者和两个对照组（年龄匹配组和年轻组）以自主方式进行行走起始任务，头部快速转动以产生预先的眼球转移，同时也进行无预先眼球转移的行走起始任务。具有平行激活水平缩放（肌肉模式）的肌肉群被识别为肌肉激活空间中的因素。在肌肉模式空间中量化协同指数稳定前后方向和内外方向的中心压力轨迹（稳定性指数）。量化准备行走时协同指数的下降（预期协同调整，ASA）。
与对照组相比，PD 患者在压力中心前后和内外两个方向的协同指数和 ASA 均显著较小。PD 和年龄匹配的对照组均显示出先前眼球转移对视动 ASA 指数的不利影响，但年轻对照组没有。
无明显姿势或步态障碍的 PD 患者显示出中心压力稳定性受损，并且在行走起始时其调整能力下降。
稳定性指数和 ASA 可能有助于监测临床前步态障碍，而较低的 ASA 可能与 PD 中出现冻结步态有关。
