title: Transcranial Doppler monitoring in Parkinson's disease: cerebrovascular compensation of orthostatic hypotension.
abstract: Despite of precipitous blood pressure falls in Parkinson's Disease (PD) patients, they may not experience syncope or postural complaints. Can cerebral blood flow regulation explain why orthostatic hypotension (OH) has often no accompanying symptoms? In patients with PD and OH (18 asymptomatic; 8 symptomatic), arterial blood pressure (ABP) as well as Doppler-detected cerebral blood flow velocity (CBFV) in middle and posterior cerebral arteries (MCA and PCA) were monitored during head-up tilt and compared with 25 controls and eight non-PD-OH patients. Analysis included the transfer function between slow spontaneous pressure and flow-oscillations. ABP and CBFV were maintained at significantly higher levels in asymptomatic than symptomatic PD-OH (ABP: 85.7 ± 10.5 vs. 66.9 ± 12.5%; MCA-FV: 83.3 ± 9.3 vs. 66.1 ± 6.8%; PCA-FV: 84.4 ± 12.2 vs. 65.9 ± 9.3% of supine). When orthostatic complaints occurred, CBFV depended directly on ABP changes (MCA r(2) = 0.64; PCA r(2) = 0.62; both p < 0.05). Despite of a tilt-induced blood pressure instability in PD-OH, the transfer function parameters did not differ from normal [phase: MCA: 46.6 ± 20.5°; PCA 39.2 ± 28.8°, gain: MCA 2.0 ± 0.7; PCA 2.9 ± 1.6)]. Results showed a normal autoregulatory response to downward blood pressure shifts in PD. Moreover, orthostatic blood pressure instability is compensated equally sufficient in anterior and posterior parts of cerebral circulation. Whether in PD patients, OH becomes symptomatic rather seems to depend on blood pressure falling below the autoregulated range.
authors.affiliation: Department of Neurology, University Hospital Aachen, Aachen, Germany. Christina.Haubrich@t-online.de
authors.forename: Christina
authors.initials: C
authors.lastname: Haubrich
authors.forename: Katrin
authors.initials: K
authors.lastname: Pies
authors.forename: Manuel
authors.initials: M
authors.lastname: Dafotakis
authors.forename: Frank
authors.initials: F
authors.lastname: Block
authors.forename: Christof
authors.initials: C
authors.lastname: Kloetzsch
authors.forename: Rolf R
authors.initials: RR
authors.lastname: Diehl
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D007024:Hypotension, Orthostatic / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging; D010300:Parkinson Disease / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D020769:Posterior Cerebral Artery / Q000000981:diagnostic imaging; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*