Objective: Proposing an inertial measurement unit (IMU)-based objective quantification method for bradykinesia evaluation in Parkinson’s disease (PD) using MDS UPDRS III.

Background: MDS-UPDRS III rating scale is one of the most widely used clinical standard for motor evaluation in PD. However, the manual evaluation of bradykinesia part can bring about subjective bias introduced by human visual.

Method: We placed an IMU on the patient’s hand back and recorded the angular velocity during pronation-supination movements. The three bradykinesia evaluation dimensions including amplitude, speed and rhythm, were independently reconstructed based on motion data [table1]. By rescoring the data using different strategies, namely Average, Hard, and Soft [figure1], we established three objective rating scores (PS-avg, PS-hard, PS-soft). We validated our approach by analyzing a total of 28 segments of data from a single patient with PD who had undergone bilateral STN DBS implantation three months before. The more affected side of limb (limbs of right side in this patient) was used for analysis. Spearman correlation coefficients was calculated between the LFP Beta band amplitude measured before each testing session and four scores (one manual rating score (PS-manual) and three objective rating scores (PS-avg, PS-hard, PS-soft) separately.

Results: The manual scores and objective scores are presented in the Figure 2, demonstrating that objective rating approach is capable of providing a more continuous rating while following the trends of manual rating [figure2]. The correlation between the STN-LFP Beta amplitude and the sum of right-side manual rigidity ratings and four kinds of PS rating scores is demonstrated. All analysis showed statistical significance [figure3], while the PS-avg demonstrated the highest correlation (r=0.733, p<0.001) and the PS-manual showed the lowest (r=0.703, p<0.001).

Conclusion: We have developed an objective quantification algorithm for the MDS-UPDRS III bradykinesia rating based on IMU data. Further study will include more subjects to test the validity and accuracy of this quantification method.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/an-imu-based-objective-quantification-method-for-bradykinesia-evaluation-in-parkinsons-disease/