title: Impairment of cerebral hemodynamic response to the cold pressor test in patients with Parkinson's disease.
abstract: OBJECTIVE
  Disturbance of the autonomic nervous system (ANS) is frequently encountered in Parkinson's disease (PD). In this study, we examined changes in systemic and cerebral hemodynamics during the cold pressor test (CPT) to determine whether cerebrovascular reactivity, controlled by the sympathetic nervous system, is intact or impaired in patients with PD.
  
  
  METHODS
  Forty-nine patients with PD and 49 sex- and age-matched non-PD subjects were evaluated. Measurements were performed in the resting state and over a period of 1min of CPT. The cerebral blood flow velocity (CBFV) and pulsatility index (PI) of the middle cerebral artery (MCA) were recorded by transcranial color-coded Doppler ultrasonography (TCCS). Mean arterial blood pressure (MAP), heart rate (HR), and end-tidal CO(2) (Et-CO(2)) were investigated simultaneously. The resistance of the cerebrovascular bed (CVR) was calculated as the ratio of mean arterial blood pressure to mean cerebral blood flow velocity (Vm). Changes of Vm, PI and CVR in response to the cold pressor test were evaluated.
  
  
  RESULTS
  Baseline values for control and PD subjects showed no statistical difference. CPT induced a significant increase in MAP, HR, and Vm in both groups. Pulsatility index (PI) and CVR were decreased in both groups during CPT. Percent increases of Vm (P<0.001) and MAP (P=0.011) were significantly higher while the percent decreases of PI (P=0.002) and CVR (P=0.007) were significantly decreased more in the non-PD group.
  
  
  CONCLUSIONS
  This study indirectly shows that ANS-mediated cerebrovascular reactivity is impaired in patients with PD. Further investigations are needed to confirm the hypothesis that using the cold pressor test to evaluate cerebrovascular reactivity might be beneficial in early diagnosis of impairment of ANS-mediated cerebrovascular autoregulation in patients with PD.
authors.affiliation: Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan; School of Medicine, Chung Shan Medical University, Taichung, Taiwan.
authors.forename: Shih-Jei
authors.initials: SJ
authors.lastname: Tsai
authors.forename: Shiuan-Chih
authors.initials: SC
authors.lastname: Chen
authors.forename: Tsong-Ming
authors.initials: TM
authors.lastname: Leu
authors.forename: Chiu-Mei
authors.initials: CM
authors.lastname: Chen
authors.forename: Hsi-Hsien
authors.initials: HH
authors.lastname: Chou
authors.forename: Hsien-Yu
authors.initials: HY
authors.lastname: Peng
authors.forename: Jiuan-Miaw
authors.initials: JM
authors.lastname: Liao
authors.forename: Tzer-Bin
authors.initials: TB
authors.lastname: Lin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation / Q000502:physiology; D003080:Cold Temperature; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods; D017585:Ultrasonography, Doppler, Transcranial; D014655:Vascular Resistance / Q000502:physiology