Cardiovagal Baroreflex Sensitivity in Parkinson's Disease and Multiple-System Atrophy.

Abstract

Background and PurposeParkinson's disease (PD) and multiple-system atrophy of the parkinsonian type (MSA-P) are progressive neurodegenerative disorders that in addition to dysfunction of the motor system also present with features of dysautonomia, frequently manifesting as orthostatic hypotension (OH). The pathophysiology of OH has been proposed to differ between these two disorders. This study investigated the spontaneous and cardiovagal baroreflex sensitivity (BRS) in Parkinson's disease patients with orthostatic hypotension (PDOH) and multiple system atrophy of Parkinsonian type with orthostatic hypotension in an attempt to differentiate the two disorders.MethodsTwo methods were used for determining the BRS: a spontaneous method (spontaneous BRS) and the reflexive baroreflex gain (cardiovagal BRS) from phases II and IV of the Valsalva maneuver (VM) in PDOH and MSA-POH.ResultsThe spontaneous BRS (5.04±0.66 ms/mm Hg vs. 4.78±0.64 ms/mm Hg, p=0.54) and the cardiovagal BRS from phase II of the VM (0.96±0.75 ms/mm Hg vs. 1.34±1.51 ms/mm Hg, p=0.76) did not differ between PDOH and MSA-POH, but the cardiovagal BRS from phase IV of the VM (0.03±0.07 ms/mm Hg vs. 2.86±2.39 ms/mm Hg, p=0.004) was significantly lower in PDOH.ConclusionsThe cardiovagal BRS from phase IV of the VM has potential for differentiating PDOH and MSA-POH, indicating a difference in the pathophysiological mechanisms underlying the autonomic dysfunction in the two disorders.