title: Basilar artery blood flow during head rotation in vertebrobasilar ischemia.
abstract: METHODS
  Forty-six patients with vertebrobasilar ischemia and 40 control subjects were examined during head rotation using transcranial Doppler ultrasonography.
  
  
  RESULTS
  In the control group, no difference in blood flow velocity through the BA was found between the neutral and rotated positions. Based on these data, a blood flow reduction in the BA of more than 20% was considered to be significantly abnormal (p < 0.01). In three of 46 patients no signal was detectable in the BA using TCD. The reduction in blood flow velocity through the BA during head rotation was strongly dependent on the condition of the VA; none of 23 patients without atherosclerotic lesions or hypoplasia of the VA developed a significant reduction in blood flow through the BA. Two of 11 patients with unilateral VA lesions had significantly reduced blood flow in the BA (27% and 31%), although both were asymptomatic. Five of nine patients with bilateral VA lesions showed a significant reduction in blood flow through the BA (mean = 52%, minimum = 30%), and four of these developed clinical symptoms such as vertigo or diplopia during the rotation maneuver.
  
  
  CONCLUSIONS
  These data suggest that patients with uni- or bilateral lesions of the VA are at risk for developing clinically relevant reductions in blood flow through the BA during head rotation. Because not all patients with VA lesions developed reduced blood flow velocity, we conclude that individual vascular mechanisms must play an important compensatory role.
authors.affiliation: Department of Neurology, Ernst Moritz Amdt University Greifswald, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Petersen
authors.forename: M
authors.initials: M
authors.lastname: von Maravic
authors.forename: J A
authors.initials: JA
authors.lastname: Zeller
authors.forename: M L
authors.initials: ML
authors.lastname: Walker
authors.forename: D
authors.initials: D
authors.lastname: Kömpf
authors.forename: C
authors.initials: C
authors.lastname: Kessler
mesh_terms: D000328:Adult; D000368:Aged; D001488:Basilar Artery / Q000503:physiopathology*; D001783:Blood Flow Velocity; D001921:Brain / Q000098:blood supply*; D002545:Brain Ischemia / Q000503:physiopathology*; D002533:Cerebral Angiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012399:Rotation; D018608:Ultrasonography, Doppler