Sudomotor and cardiovascular dysfunction in patients with early untreated Parkinson's disease

According to Braak staging of Parkinson's disease (PD), detection of autonomic dysfunction would help with early diagnosis of PD.

To determine whether the autonomic nervous system is involved in the early stage of PD, we evaluated cardiovascular and sudomotor function in early untreated PD patients.

Orthostatic blood pressure regulation, heart rate variability, skin vasomotor function, and palmar sympathetic sweat responses were examined in 50 early untreated PD patients and 20 healthy control subjects.

The mean decrease in systolic blood pressure during head-up tilt in PD patients was mildly but significantly larger than in controls (p = 0.0001). There were no differences between the 2 groups in heart rate variability, with analysis of low frequency (LF; mediated by baroreflex feedback), and high frequency (HF; mainly reflecting parasympathetic vagal) modulation. However, LF/HF, an index of sympatho-parasympathetic balance, was lower in the PD group than in controls (p = 0.02). Amplitudes of palmar sweat responses to deep inspiration (p = 0.004), mental arithmetic (p = 0.01), and exercise (p = 0.01) in PD patients were lower than in controls, with negative correlations with motor severity. Amplitudes of palmar skin vasomotor reflexes in PD patients did not differ from controls.

Our study indicates impairment of sympathetic cardiovascular and sudomotor function with orthostatic dysregulation of blood pressure control, reduced LF/HF and reduction in palm sweat responses even in early untreated PD patients.