INTRACRANIAL HEMODYNAMICS 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 4 5-77 years) with longstanding unilateral occlusion of the internal car otid 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 mea n velocities and pulsatility index in the middle cerebral artery, ante rior 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 velociti es 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)) si de than those found in the middle cerebral artery (39.2 +/- 13.7 and 5 0.9 +/- 8.5 cm sec(-1)). In two patients a decrease of mean velocity a fter acetazolamide was noted in middle cerebral artery indicating 'ste al' effect. In another 4 patients, poor vasomotor response was seen wi th less than 11% of mean velocity increase in the middle cerebral arte ry. Differences between posterior cerebral artery on the occluded and nonoccluded side were insignificant as well as those between middle an d 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 ce rebral artery on the occluded side, implying different function of the se vessels as collaterals.