Exploring Cardiovascular Autonomic Function before and after Chronic Deep Brain Stimulation in Parkinson's Disease

Background: Blood pressure control in Parkinson's disease (PD) under subthalamic deep brain stimulation (STN-DBS) is influenced by several intertwined aspects, including autonomic failure and levodopa treatment. Objective: To evaluate the effect of chronic STN-DBS, levodopa, and their combination on cardiovascular autonomic functions in PD. Methods: We performed cardiovascular reflex tests (CRTs) before and 6-months after STN-DBS surgery in 20 PD patients (pre-DBS vs. post-DBS). CRTs were executed without and with medication (med-OFF vs. med-ON). Results: CRT results and occurrence of neurogenic orthostatic hypotension (OH) did not differ between pre- and post-DBS studies in med-OFF condition. After levodopa intake, the BP decrease during HUTT was significantly greater compared to med-OFF, both at pre-DBS and post-DBS evaluation. Levodopa-induced OH was documented in 25% and 5% of patients in pre-DBS/med-ON and post-DBS/med-ON study. Conclusion: Chronic stimulation did not influence cardiovascular responses, while levodopa exerts a relevant hypotensive effect. The proportion of patients presenting levodopa-induced OH decreases after STN-DBS surgery.