Walking Quality Improves With Dopaminergic Medications In Parkinson’S Disease Patients Considering Deep Brain Stimulation Therapy

Background: Deep brain stimulation (DBS) improves tremor in patients with Parkinson's disease (PD), but its effects on gait, while often optimistic, are less understood. The Enhanced Gait Variability Index (eGVI) is a validated measure of walking quality that yields a composite score referencing a healthy population. Whether motor symptoms respond to dopaminergic medications is a determinant for DBS candidacy and efficacy; however, the few items from the Unified Parkinson Disease Rating Scale (UPDRS part 3) related to gait and balance are relatively coarse. Ancillary measures such as eGVI could provide a more detailed view of gait quality and responsiveness to medications before DBS. Purpose: To determine if eGVI is responsive to dopaminergic medications during different walking conditions in people with PD who are candidates for DBS surgery. Methods: 29 people with PD walked over an instrumented walkway during comfortable (CW), maximum (MW), and backward (BW) walking conditions. EGVI uses five spatial-temporal gait parameters (step length, step time, stance time, single support time, and stride velocity) to generate a composite score for variability. eGVI<100 indicates low variability, eGVI = 100, similar variability, and EGVI>100 high variability versus a comparable healthy population. The Friedman Test compared walking conditions by medication state (OFF/ON). Results: We observed a significant difference in EGVI by medication (p < 0.02; Table 1). Post hoc Wilcoxon signed-rank tests revealed significant improvements in eGVI on the ‘on’ medication state during CW (p = 0.004) & MW (p = 0.002) but not for BW (p = 0.09). Conclusion: The composite measure of gait eGVI is responsive to dopaminergic medications in PD patients considering DBS surgery. Assessing eGVI responsiveness to dopaminergic medications could aid in making decisions for candidates eligible for DBS. Future studies should link pre-operative eGVI improvements to outcomes after DBS surgery. Table 1: - Means, Standard Deviations, and Median Interquartile Ranges for eGVI During Different Medication States and Walking Conditions Condition N Mean Std. Dev Min Max Percentiles 25th 50th (Median) 75th CW-OFF 29 115.9 20.4 96.2 166.1 100.9 105.1 128.5 CW-ON 29 107.4 11.2 95.5 137.9 100 103 114 MW-OFF 29 113.3 19.3 93.5 174 100 106.1 119.8 MW-ON 29 105.6 10.6 93 142.5 100 100 111.2 BW-OFF 29 140.8 14.0 124.9 188.1 131.9 135.2 144.5 BW-ON 29 135.4 8.7 112 149.5 129.9 138 141.9