The aim of this study was to evaluate the autonomic neural function in Parkinson's disease (PD) and multiple system atrophy (MSA) with head-up tilt test and spectral analysis of cardiovascular parameters. This study included 15 patients with MSA, 15 patients with PD, and 29 healthy control (HC) subjects. High frequency power of the RR interval (RR-HF), the ratio of low frequency power of RR interval to RR-HF (RR-LF/HF) and LF power of systolic BP were used to evaluate parasympathetic, cardiac sympathetic and vasomotor sympathetic functions, respectively. Both patients with PD and MSA showed orthostatic hypotension and lower parasympathetic function (RR-HF) at tilt position as compared to HC subjects. Cardiac sympathetic function (RR-LF/HF) was significantly high in patients with PD than MSA at supine position. RR-LF/HF tended to increase in MSA and HC, but decreased in PD by tilting. Consequently, the change of the ratio due to tilting (ΔRR-LF/HF) was significantly lower in patients with PD than in HC subjects. Further analysis showed that compared to mild stage of PD, RR-LF/HF at the supine position was significantly higher in advanced stage. By tilting, it was increased in mild stage and decreased in the advanced stage of PD, causing ΔRR-LF/HF to decrease significantly in the advanced stage. Thus, we demonstrated that spectral analysis of cardiovascular parameters is useful to identify sympathetic and parasympathetic disorders in MSA and PD. High cardiac sympathetic function at the supine position, and its reduction by tilting might be a characteristic feature of PD, especially in the advanced stage.

Background and Aims: Reactive hyperemia-peripheral arterial tonometry (RH-PAT) has been developed to detect early stage vascular dysfunction. Recent studies have suggested that Reactive hyperemia index (RHI) assessed using RH-PAT could be used to predict the mortality of subjects with high risks for cardiovascular events. On the other hand, carotid intima-media thickness (IMT), pulse wave velocity (PWV), and/or cardio-ankle vascular index (CAVI) have been used as screening tools for vascular disorders. Since obesity and metabolic syndrome are the risk factors for cardiovascular events, we aimed to examine the association of RHI, CAVI, and carotid artery plaque scores with the body mass index (BMI). Methods: The participants of this study were 39 Japanese subjects who were admitted at the Department of Liver Disease of Shimane University Hospital between August and December 2016 (mean age, 62 years). RH-PAT findings, CAVI, and carotid IMT were evaluated, and their associations with BMI were analyzed. Carotid IMT and plaque score (PS) were evaluated by ultrasonography following the standard protocol. A score of less than 1.67 was defined as a low RHI. Results: The PS was associated with age (r=0.511, p<0.0001) but not with BMI. Interestingly, CAVI had a positive association with age (r=0.706, p<0.0001) and an inverse association with BMI (r=−0.511, p<0.0001). In contrast, RHI had no significant association with age and BMI. Among 14 patients with non-alcoholic steatohepatitis (NASH) or non-alcoholic fatty liver disease (NAFLD) with BMI! 25, only one patient had high CAVI (>9.0) whereas 6 patients had low RHI. Conclusions: NASH/NAFLD subjects, especially those with obesity, are good candidates for RH-PAT examination to detect early stage of vascular failure.