Sympathetic Dysfunction As an Early Indicator of Autonomic Involvement in Parkinson's Disease

Purpose: The specific characteristics of autonomic involvement in patients with early Parkinson's disease (PD) are unclear. This study aimed to evaluate the characteristics of autonomic dysfunction in drug-naïve patients with early-stage PD without orthostatic hypotension (OH) by analyzing Valsalva maneuver (VM) parameters.

Methods: We retrospectively analyzed drug-naïve patients without orthostatic hypotension (n = 61) and controls (n = 20). The patients were subcategorized into early PD (n = 35) and mid-PD (n = 26) groups on the basis of the Hoehn and Yahr staging. VM parameters, including changes in systolic blood pressure at late phase 2 (∆SBP), ∆HR, Valsalva ratio (VR), pressure recovery time, adrenergic baroreflex sensitivity, and vagal baroreflex sensitivity, were assessed.

Results: In the early PD group, ∆SBP, a marker of sympathetic function, was significantly lower compared with that in controls (risk ratio = 0.95, P = 0.027). Receiver operating characteristic (ROC) curve analysis showed an optimal cut-off value of -10 mmHg for ∆SBP [P = 0.002, area under the curve (AUC): 0.737]. VR exhibited an inverse relationship with Unified Parkinson's Disease Rating Scale Part 3 scores in the multivariable regression analysis (VR: P = 0.038, β = -28.61), whereas age showed a positive relationship (age: P = 0.027, β = 0.35).

Conclusion: The ∆BP parameter of the VM may help detect autonomic nervous system involvement in early-PD without OH. Our results suggest that sympathetic dysfunction is an early manifestation of autonomic dysfunction in patients with PD.