Acetazolamide stimulation test in patients with unilateral internal carotid artery obstructions using transcranial Doppler and ^99mTc-HM-PAO- Spect

Fifteen patients with symptoms of cerebral ischaemia and angiographically confirmed unilateral stenoses or occlusions of the extracranial internal carotid artery (ICA) and 20 controls were studied by a 2 MHz transcranial Doppler (TCD) at rest and after stimulation with 1 g acetazolamide i.v., a cerebral vasodilator. In addition,-the patients underwent ^99mTc-HM-PAO- Spect measurement of regional cerebral blood flow (rCBF) at rest and after stimulation with 1 g acetazolamide. In 10 patients with ICA stenoses >80% or occlusions, time-mean velocity (V(mean)) increase and pulsatility index (PI) decrease in the postobstructive middle cerebral artery (MCA) as well as the increase of the ipsilateral rCBF were reduced in comparison with the contralateral side. The remaining 5 patients showed a normal V(mean) increase and PI decrease in TCD.