ABSTRACT
BACKGROUND AND PURPOSE: It is not clear how cardiovascular autonomic nervous system dysfunction can affect falls in Parkinson disease (PD) patients. The aim of the study was to evaluate cardiovascular autonomic responses to orthostatic stress and occurrence of falls in PD patients over a period of 1-2 years. MATERIAL AND METHODS: In 53 patients, who either experienced at least one fall during 12 months preceding the study onset (fallers) or did not fall (non-fallers), we monitored RR intervals (RRI), heart rate (HR) and systolic (SBP) and diastolic (DBP) blood pressure, and calculated the coefficient of variation of RRI (RRI-CoV) and the ratio of low to high frequency spectral powers of RRI oscillations (LF/HF) at rest and upon tilting at study entry and after at least 12 months. Based on the number of falls at study closure, we identified three subgroups: non-fallers, chronic fallers, and new fallers. RESULTS: At study entry, RR-CoV, SBP, or DBP did not differ between fallers and non-fallers, while LF/HF ratios were lower in fallers than non-fallers at rest and upon tilting. After the follow-up period, HR and RRI-CoV responses to head-up tilt were reduced in new fallers as compared to study entry, whereas these variables remained unchanged during the study in non-fallers and chronic fallers. Prevalence of orthostatic hypotension did not differ between subgroups of patients. CONCLUSIONS: Cardiac responses to orthostatic stress deteriorate in PD patients who begin to fall. Orthostatic blood pressure responses remain unchanged over time and are not associated with falls in PD.
