Evaluation of autonomic nervous function by assessing baroreceptor reflex

: The autonomic nervous functional tests assessing baroreceptor reflex (BR) were described. I. Head-up tilt test: Sympathetic nervous function is activated and alginine-vasopressin is secreted through the BR. Orthostatic hypotension is induced by BR dysfunction. II. Spectral analysis of heart and blood pressure: High-frequency power in R-R interval variability indicates parasympathetic function and low-frequency power may reflect BR function. Low-frequency power in blood pressure may indicate sympathetic nervous function. However, spectral analysis of them can not detect a sympathetic nervous hyperfunction. III. Baroreceptor sensitivity during the Valsalva maneuver: Baroreceptor sensitivity is obtained from the correlation of systolic blood pressure and RR interval. It decreases in early stage of Parkinson's disease. IV. Correlation of heart rate and blood pressure: The correlation of them may reflect qualitative differences in the central autonomic dysfunction.