Feasibility of the Virtual Peg Insertion Test to assess upper limb function in Parkinson’s Disease: A longitudinal pilot study
Feasibility of the Virtual Peg Insertion Test to assess upper limb function in Parkinson’s Disease: A longitudinal pilot study
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Original abstract
Abstract Background. Upper limb sensorimotor dysfunction in Parkinson's Disease (PD) is poorly captured by existing clinical assessments, which lack sensitivity to movement quality and do not capture within-session variability. The Virtual Peg Insertion Test (VPIT) is a previously developed technology-based assessment capable of quantifying movement smoothness, speed, efficiency, and grip force control during a goal-directed task, but its feasibility and validity in PD have not yet been established. Methods. Eight patients with PD underwent baseline VPIT testing with five VPIT repetitions per hand alongside conventional motor assessments. The protocol comprised four sessions over 12 months (baseline, 3, 6, 12 months). Feasibility, usability, convergent validity, within-session variability, and longitudinal trajectories were assessed against an age- and gender-matched normative database (n = 124). Results. Three of eight patients (37.5%) could not complete the VPIT at baseline, with task failure linked to low MoCA visuospatial subscores rather than motor severity. Retention among completers was 100%. PD patients showed significant impairment in movement speed (one-sample Wilcoxon signed-rank test, d = −1.84, p < 0.01) and grip force control (d = −0.86, p < 0.05). Notably, individual patients showed severe multi-domain VPIT impairment despite normal performance on conventional assessments. No significant group-level longitudinal change in conventional assessments or the VPIT was observed. Individual evolution of upper limb function over time showed marked heterogeneity. Conclusions. The VPIT was feasible for repeated upper limb assessment in PD over 12 months, with task suitability primarily determined by visuospatial rather than motor ability, suggesting the MoCA visuospatial subscore as a candidate screening criterion. Despite largely normal performance on conventional assessments, the VPIT detected significant impairment in movement speed and grip force control with large effect sizes, and detected impairment in a patient whose conventional assessment scores were within normal limits — underscoring the added value of movement-quality metrics. Individual longitudinal patterns highlighted the value of bilateral and multi-domain assessment for detecting asymmetric disease progression in PD patients. Together, these findings support the VPIT as a sensitive complement to conventional upper limb assessments in PD, and motivate larger longitudinal studies with standardized medication-state protocols and extended observation windows.