CBF and transcranial Doppler sonography during vasodilatory stress tests in patients with common carotid artery occlusion

Abstract

Cerebral blood flow (CBF) and the cerebral vasoreactivity was measured in patients with cerebrovascular disease and longstanding occlusion of the common carotid artery (CCA). In addition, regional CBF was correlated with transcranial doppler (TCD) measurements at baseline and during 6% CO₂ inhalation and after intravenous administration of 1 g of acetazolamide. Twelve patients with a mean age of 62 years (range 45 to 71 years) were included, and the data compared to age-matched healthy controls. CBF was measured by intravenous injection of xenon-133 and SPECT (Tomomatic 564). TCD of the middle cerebral artery (MCA) was done by EME TC-64B. A very low global CBF value of 28 + 5 (SD) ml 100 g^-1 min ^-7 was found at baseline as compared to 55 ± 5 ml 100 g^-1 min^-1 in the normal controls. During 6% CO 2-inhalation and after acetazolamide administration, CBF increased by 58 + 24% and 51 ± 21%, respectively, indicating substantial collateral supply. Correlative analysis of CBF in the MCA territory and TCD in the MCA showed statistical significance only for the pooled data, i.e. compiling the data obtained during baseline and the two vasodilatory tests, and then only for the mean and peak TCD velocity (e.g. r = 0.59, p < 0.002, n = 35, mean velocity, right side). We conclude that TCD measurements do not predict regional CBF in patients with CCA occlusion. The study emphasizes that these two methods yield supplementary information, with TCD measurements providing information of the circle of Willis and CBF studies of the flow distribution.

Key Words::

• Cerebral blood flow
• transcranial Doppler
• CO₂ inhalation
• occlusive cerebrovascular disease