title: Cardiovagal Baroreflex Sensitivity in Parkinson's Disease and Multiple-System Atrophy.
abstract: OBJECTIVE
  Parkinson'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 (PD(OH)) and multiple system atrophy of Parkinsonian type with orthostatic hypotension in an attempt to differentiate the two disorders.
  
  
  METHODS
  Two 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 PD(OH) and MSA-P(OH).
  
  
  RESULTS
  The 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 PD(OH) and MSA-P(OH), 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 PD(OH).
  
  
  CONCLUSIONS
  The cardiovagal BRS from phase IV of the VM has potential for differentiating PD(OH) and MSA-P(OH), indicating a difference in the pathophysiological mechanisms underlying the autonomic dysfunction in the two disorders.
authors: Department of Physiology, AIIMS, New Delhi, India. shanksroy2903@gmail.com.
authors: Sankanika
authors: S
authors: Roy
authors: Department of Physiology, AIIMS, New Delhi, India.
authors: Ashok Kumar
authors: AK
authors: Jaryal
authors: Department of Neurology, AIIMS, New Delhi, India.
authors: Achal Kumar
authors: AK
authors: Srivastava
authors: Department of Physiology, AIIMS, New Delhi, India.
authors: Kishore Kumar
authors: KK
authors: Deepak
keywords: Parkinson's disease; baroreflex sensitivity; multiple system atrophy; valsalva maneuver