Vasomotor regulation in patients with multiple system atrophy.

To investigate the vasomotor regulation in multiple system atrophy (MSA), we simultaneously recorded muscle sympathetic nerve activity (MSNA), heart rate, and blood pressure in 14 MSA patients without syncope and 18 healthy subjects. Resting MSNA bursts were significantly less frequent in MSA patients than healthy subjects (p < 0.001), while the increase of MSNA bursts with head-up tilt was significantly greater in MSA patients (p < 0.01). In patients with MSA, orthostatic hypotension may be prevented by an augmented MSNA response.