Objective: To validate quantitative metrics using goniometer and TAS test video-based finger tapping in Parkinson’s disease.

Background: Clinical assessment of finger tapping in Parkinson’s disease (PD) relies on the Unified Parkinson’s Disease Rating Scale (UPDRS), which is subject to variability even with movement disorder experts. Instrumented tapping analysis offers continuous, objective quantification, but validation against established clinical benchmarks remains limited.

Method: 10 patients with PD completed standardised finger tapping tasks in both the OFF and ON states. Quantitative metrics capturing tapping amplitude, speed and variability were captured simultaneously using TAS test and goniometers from the most affected hand. Each technique was independently compared with blinded UPDRS item 3.4 scores.

Results: The median age was 62 years (IQR 57.1-67.2) with a median disease duration of 10 years (IQR 7.2–13.2). Moderate Spearman correlations were observed for metrics independently from both systems. The strongest associations for goniometer-based assessment were standard deviation of inter-tap interval (ρ=0.62) coefficient of variation of tap closing duration and tap frequency (ρ=0.59 and ρ=0.58) respectively. While TAS test demonstrated similar correlation across UPDRS severity, the most significant associations were mean inter-tap interval (ρ=0.52), total tap count (ρ= -0.51) and mean closing duration (ρ=0.50). p values of <0.05 were classified as significant.

Conclusion: Both goniometer-based and TAS test-based quantitative metrics demonstrate correlation with blinded UPDRS finger tapping ratings in PD in this pilot study. Variability indices showed the strongest correlation. Larger cohorts are necessary to evaluate whether such variability metrics are particularly sensitive to bradykinesia impairments in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/validation-of-instrumented-finger-tapping-metrics-for-bradykinesia-in-parkinsons-disease/