Differences in acetazolamide vasoreactivity in patients with acute and chronic occlusion of the internal carotid artery.

Using a xenon-enhanced computed tomography (Xe-CT) system, we measured cerebral blood flow (CBF) and acetazolamide vasoreactivity in 3 major vascular territories, the thalamus and putamen on both sides in 3 groups of patients undergoing the balloon occlusion test (BOT), with internal carotid occlusion (ICO) and with open carotids.In the ICO group, although the CBFs on the occluded side were similar to those in the BOT group, the vasoreactivity was significantly higher. The CBFs on the contralateral side were lower than those in the BOT group, but the vasoreactivity was similar. The vasoreactivity of the MCA on the occluded side mostly correlated with that in the other areas, similar to the results obtained in the open carotid group, although it was poorly correlated with other areas in the BOT group. Carotid artery occlusion may reduce CBF in a large area with restoration of vasoreactivity in the chronic stage.