Cerebral autoregulation in middle cerebral artery territory precedes that of posterior cerebral artery in human cortex.
OBJECTIVE
Cerebral autoregulation tends to compensate changes in arterial blood pressure. This mechanism of cerebral blood flow regulation appears to be insufficient in orthostatic dysregulation in which mainly vertebrobasilar symptoms occur. To investigate this hypothesis, we compared cerebral autoregulation in the vascular territory of the carotic and vertebrobasilar vessel system using a leg cuff test to induce a drop in cerebral perfusion pressure.


METHODS
We measured blood flow velocity in 10 healthy young volunteers (aged 26.7 +/- 0.3 years, 7 male) simultaneously in the middle and posterior cerebral artery with transcranial Doppler sonography. A leg cuff test was used to induce a sudden decrease in arterial blood pressure. Arterial blood pressure was measured with a non-invasive photoplethysmographic method. The averaged relative blood flow velocity changes due to the pressure step were compared between both vessel territories.


RESULTS
After cuff release systolic (diastolic) blood flow velocity increased with a latency of 1.1 +/- 0.3 s (1.8 +/- 0.4 s). Due to a smaller decrease and identical time courses cerebral blood flow velocity recovery in the posterior cerebral artery precedes blood flow recovery in the middle cerebral artery by 0.9 +/- 0.3 s.


CONCLUSIONS
Cerebral autoregulation in the carotid and vertebrobasilar system does not differ in the time course of the blood flow velocity recovery. Due to a smaller decrease in blood flow velocity recovery in the posterior cerebral artery precedes recovery in the middle cerebral artery by nearly 1 s.
Rosengarten
B
B
Justus-Liebig University of Giessen, Faculty of Medicine, Department of Neurology, Giessen, Germany.
Kaps
M
M
D000328:Adult; D001488:Basilar Artery / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D002339:Carotid Arteries / Q000502:physiology; D002540:Cerebral Cortex / Q000098:blood supply* / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D008297:Male; D020768:Middle Cerebral Artery / Q000502:physiology*; D020769:Posterior Cerebral Artery / Q000502:physiology*; D017585:Ultrasonography, Doppler, Transcranial; D014711:Vertebral Artery / Q000502:physiology