CEREBRAL VASOREACTIVITY IN UNILATERAL CAROTID-ARTERY DISEASE - A COMPARISON OF BLOOD-FLOW VELOCITY AND REGIONAL CEREBRAL BLOOD-FLOW MEASUREMENTS

Background and Purpose Hemodynamic information obtained by assessing c erebral vasoreactivity is of clinical interest and may have prognostic significance in patients with occlusive carotid disease. The aim of t his study was to compare the results of transcranial Doppler and regio nal cerebral blood flow studies when used to assess cerebral vasoreact ivity. Methods Blood flow velocities in both middle cerebral arteries and regional cerebral blood flow in their respective perfusion territo ries were compared in 52 patients with severe unilateral carotid steno sis or occlusion. The studies were first performed under basal conditi ons and repeated after the intravenous administration of Ig acetazolam ide. Results Asymmetry (normal compared with pathological side) in mid dle cerebral artery blood velocity increase was significantly greater than the asymmetry in cerebral blood flow increase in the perfusion te rritories of the arteries. A significant correlation (r=.63, P<.0001) was found between asymmetry in percent velocity increase and asymmetry in absolute cerebral blood flow increase. The two methods agreed in t heir assessment of either a normal or a reduced vasoreactivity in 38 s ubjects and disagreed in 14. In six of the latter patients, who had no evidence of cerebral infarction, the asymmetry in velocity increase w as abnormal, whereas asymmetry in flow increase was assessed as normal . Conclusions We found a good correlation between the asymmetry in reg ional cerebral blood flow increase in the middle cerebral artery perfu sion territories and asymmetry in the velocity increase in the middle cerebral arteries after administration of acetazolamide. These results suggest that transcranial Doppler examination combined with the aceta zolamide test may be used in clinical situations to assess cerebral va soreactivity.