Cerebral Vasoreactivity by Transcranial Doppler and Brain SPECT in Patients with Unilateral Carotid Stenosis

ABSTRACT

BACKGROUND: Cerebral vasoreactivity (CVR) is known as having insufficient hemodynamic circulation. However, available information for its clinical interpretation is scant. We attempted to find the relationship of CVR with parameters such as stenosis degree and collateral patterns. METHODS: This study was prospectively conducted in 37 patients with more than 50% angiographically proven unilateral carotid stenosis. The relative change of mean flow velocity before and after an acetazolamide challenge was calculated by transcranial Doppler sonography (TCD) and the results were compared with single photon emission computed tomography (SPECT) results. The degree of stenosis and collateral flow patterns were estimated and classified by conventional angiography. RESULTS: The CVR of middle cerebral artery (MCA) was significantly decreased in the ipsilateral side to the carotid stenosis (p<0.05). The CVR impairment was more severe when symptomatic stenosis was present (p=0.04). There was a significant correlation between the degree of carotid stenosis and the CVR (p<0.01). In the area of impaired CVR by SPECT, the estimated CVR was significantly lower (p<0.05), even to the negative value, implying that there is an actually steal phenomenon in that area. CONCLUSIONS: TCD is a useful tool for the assessment of CVR, which can give diverse clinical information based upon the degree of stenosis.