Objective: Transcranial Doppler (TCD) findings for evaluation of the severity of vasospasm (VSP) in patients with ruptured aneurysmal subarachnoid hemorrhage are controversial. To clarify these TCD findings, intra-arterial digital subtraction angiography was used to simultaneously investigate the angiographic features of cerebral vessels and the cerebral circulation time (CCT).
Methods: Fifty patients with ruptured aneurysms, for whom computed tomographic scans indicated Fisher Grade III subarachnoid hemorrhage, were investigated. Aneurysmal neck clipping was performed in the acute stage. The mean flow velocity (MFV) at the M1 segment was measured using TCD ultrasonography. Intra-arterial digital subtraction angiography was used to simultaneously investigate angiographic features and CCTs on Days 7 to 13. The CCT was defined as the time difference between the two peaks in optical density curves recorded at the carotid artery (C3-C4 portion) and the ascending vein, after contrast material injection. Angiographic VSP was categorized using a modification of the Fisher classification.
Results: Angiograms for 9, 25, and 16 patients showed no, slight to moderate, and severe VSP, respectively. The MFVs of the patients with no, slight to moderate, and severe VSP were 70, 115, and 116 cm/s, respectively. No significant difference among the three groups could be observed. The mean CCTs of the patients with no, slight to moderate, and severe VSP were 4.1, 4.6, and 6.5 seconds, respectively. The CCTs of the patients with severe VSP differed significantly from those of the patients with no or slight to moderate VSP. The patients with severe VSP were divided into two groups. One group included eight patients with severe VSP at proximal sites (the internal carotid artery to the M1 segment), and the other included eight patients with severe VSP extending to the M2 segment and more peripheral sites. The mean CCT of the former group (5.3 s) was significantly different from that of the latter (7.5 s), and the MFV of the former group (128 cm/s) was significantly higher than that of the latter (81 cm/s). The clinical outcomes for the latter patients were more serious than those for the former patients.
Conclusion: This study suggests that the MFV at the M1 segment is inadequate for estimation of the severity of VSP extending to vessels more peripheral than the M1 segment. Furthermore, severe VSP extending to more peripheral sites can produce more serious ischemic insults, compared with that localized to basal vessels. Patients with negative TCD results and clinical features suggesting the development of VSP should undergo quantitative investigation of cerebral circulatory parameters, such as the CCT, using intra-arterial digital subtraction angiography.