Intracranial haemodynamics during vasomotor stress test in unilateral internal carotid artery occlusion estimated by 3-D transcranial Doppler scanner

Seventeen patients, 14 males and 3 females, mean age 64 years (range 45-77 years) with longstanding unilateral occlusion of the internal carotid artery and minimal neurological deficit, were evaluated in order to find criteria for potential benefit of extracranial-intracranial by-pass surgery. 3-D transcranial Doppler was used for estimation of mean velocities and pulsatility index in the middle cerebral artery, anterior cerebral artery and posterior cerebral artery before and after iv injection of 1 g acetazolamide. The anterior cerebral artery was the supplying vessel to the occluded side in 16 patients and mean velocities were significantly (p <0.001) faster on the occluded (59.3 ±14.5 cm sec–1) and nonoccluded (91.6 + 29.6 cm sec–1, p <0.05)) side than those found in the middle cerebral artery (39.2±13.7 and 50.9±8.5 cm sec–1). In two patients a decrease of mean velocity after acetazolamide was noted in middle cerebral artery indicating ‘steal’ effect. In another 4 patients, poor vasomotor response was seen with less than 11% of mean velocity increase in the middle cerebral artery. Differences between posterior cerebral artery on the occluded and nonoccluded side were insignificant as well as those between middle and posterior on the occluded side. Resting values of pulsatility index differed significantly (p<0.01) only between anterior and posterior cerebral artery on the nonoccluded side. After acetazolamide a slight decrease of PI was seen in all vessels with the exception of posterior cerebral artery on the occluded side, and significant difference (p<0.05) occurred between pulsatility index in anterior and posterior cerebral artery on the occluded side, implying different function of these vessels as collaterals. [Neurol Res 1995; 17: 137–143]