Assessment of cerebrovascular reactivity by acetazolamide TCD

초록

Background and Purpose : Single-photon emission computed tomography (SPECT) after acetazolamide infusion has been used for the evaluation of cerebrovascular reactivity (CVR), but application of transcranial Doppler(TCD) for the same purpose has been scanty. We tried to evaluate CVR by TCD after acetazolamide infusion, particularly focusing on the absolute cerebral blood flow (CBF) change in the hemodynamically significant carotid stenosis. Subjects and Methods : Twenty-seven angiographically confirmed carotid stenosis patients were included. CVR was assessed by TCD before and after acetazolamide infusion, and the results were compared with that of SPECT. We classified the patients into different groups by the pattern of collateral pathway, patient’s sign, electroencephalography, SPECT, degree of internal carotid artery (ICA) stenosis, and assessed individual CVR. Results : Vasomotor response was asymmetrical between symptomatic and contralateral asymptomatic side, without statistical significance. But in contrast to other vessels, CVR of the ophthalmic artery on the symptomatic side was more increased than that of contralateral side. All collateral pathways showed reduced CVR in middle cerebral artery. The correlation between the results of TCD and SPECT was significant (p=0.03). In the groups divided by the presenting sign, ICA stenosis of symptomatic side, and SPECT, the difference of MVR was significant. Discussion : SPECT results combined with acetazolamide correlate well with TCD results. Asymmetrical CVR between stenotic and non-stenotic side is also noticed in the PCA territory. Circulatory disturbance in anterior circulation probably influence posterior circulation too. CVR of individual artery is not impaired if this artery has a function as a collateral pathway. The presence of an ophthalmic artery pathway may provide the first evidence of disturbed CVR.