Development of a new methodology for quantitative analysis of rigidity in parkinson's disease

Abstract

Introduction: Parkinson’s disease (PD) is a chronic neurodegenerative disorder that pre- dominantly impairs motor function and affects millions of people worldwide. Rigidity is one of the main symptoms of PD and is present in around 89% of patients. This rigidity makes it difficult to move limbs, affecting the quality of life of these people. The assessment of rigidity is of great importance in clinical practice to monitor the rehabilitation process. Traditional methods for assessing rigidity, such as the Movement Disorder Society - Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) have limitations, leading to the exploration of novel approaches. However, there are still no standardised quantitative measures for this assessment. Therefore, there is great interest in implementing new methods that can adequately quantify this disorder. Meth- ods that use surface Electromyography (sEMG) and joint amplitude sensors are very promising. Objective: The general objective of this research is to propose and evaluate a method for the quantitative assessment of wrist rigidity in patients with PD, using inertial sensors and sEMG. Methods: Initially, a literature review was conducted to identify the most suitable and consis- tent sensors for this purpose. Based on such review, an experimental protocol was developed that incorporates a variety of movements, including active, slow passive, and fast passive stretches, to capture different aspects of rigidity. The protocol also includes participant interaction with the RehaBEElitation, a Serious Game (SG) that aims to provide an engaging and accessible approach to assessing rigidity. For the study, 15 people with PD were evaluated, in the ON and OFF states of the medication and 15 healthy people, matched in sex and age. Results and Discussion: The main findings of this research highlight speed as a crucial determinant in the manifestation of rigidity in individuals with PD. It was observed that fast passive movements were the most ef- fective in causing and highlighting rigidity, while slow passive movements showed less significant results. Furthermore, phase 4 of RehaBEElitation emerged as a highlight, proving to be crucial for identifying and evaluating rigidity. Features estimated from signals of accelerometers and gyroscopes were particularly notable, demonstrating strong correlation with MDS-UPDRS as- sessment, and offering valuable insights into the movement dynamics. On the other hand, sEMG proved to be more effective, in detecting rigidity, when movements were ordered, highlighting the importance of muscular coordination in assessing rigidity when using this method. These findings highlight the complexity of rigidity in PD and the need for multifaceted and sensitive ap- proaches to its assessment and understanding. Conclusion: This study successfully developed and implemented a new method to quantify wrist rigidity in individuals with PD. The results demonstrated strong correlations between sensor data and clinical assessments, indicating the effectiveness of the developed method in accurately quantifying wrist rigidity in different disease states. These findings underscore the potential of the proposed approach to improve the clini- cal management of PD, offering valuable insights into motor symptoms and paving the way for personalized interventions tailored to address rigidity and improve quality of life for PD patients