Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran.
Djawad Movafaghian Research Center in Rehab Technologies, Sharif University of Technology, Tehran, Iran.
J Neuroeng Rehabil. 2024 Feb 15;21(1):25. doi: 10.1186/s12984-024-01321-0.
Parkinson's disease targets patients' cognitive and motor abilities, including postural control. Many studies have been carried out to introduce mathematical models for a better understanding of postural control in such patients and the relation between the model parameters and the clinical assessments. So far, these studies have addressed this connection merely in static tests, such as quiet stance. The aim of this study is to develop a model for voluntary lean, and as such, identify the model parameters for both PD patients and healthy subjects from experimental data. The proposed model comprises planning and control sections. The model parameters for the planning section were extracted from the time response characteristics. Parameters for the control section were identified based on the spatial characteristics of the center-of-pressure (COP) response using an optimization process. 24 PD patients along with 24 matched healthy subjects participated in the study. The results showed a significant difference between the two groups in terms of temporal parameters for the planning section. This difference emphasizes bradykinesia as an essential symptom of PD. Also, differences were found for the postural control section. In all directions, the proportional gain of the feedback controller was significantly larger in PD patients; however, the gain of the feedforward controller was significantly smaller in PD patients. Furthermore, the control gains were strongly correlated with the clinical scales (Functional Reach Test and Unified Parkinson's Disease Rating Scale) in certain directions. In conclusion, the new model helps to better understand and quantify some PD symptoms in voluntary lean tasks.
帕金森病会影响患者的认知和运动能力，包括姿势控制。为了更好地理解此类患者的姿势控制以及模型参数与临床评估之间的关系，已经进行了许多研究来引入数学模型。到目前为止，这些研究仅在静态测试（如安静站立）中解决了这种联系。本研究旨在开发一个自愿倾斜模型，并从实验数据中为 PD 患者和健康受试者确定模型参数。所提出的模型包括规划和控制部分。规划部分的模型参数是从时间响应特性中提取的。控制部分的参数是基于使用优化过程的压力中心（COP）响应的空间特征来确定的。24 名 PD 患者和 24 名匹配的健康受试者参加了这项研究。结果表明，在规划部分的时间参数方面，两组之间存在显著差异。这种差异强调了运动迟缓是 PD 的一个重要症状。此外，在姿势控制部分也发现了差异。在所有方向上，PD 患者的反馈控制器的比例增益明显更大；然而，PD 患者的前馈控制器的增益明显较小。此外，在某些方向上，控制增益与临床量表（功能性伸展测试和统一帕金森病评定量表）强烈相关。总之，新模型有助于更好地理解和量化自愿倾斜任务中的一些 PD 症状。
