Assessment of Regional Cerebral Blood Flow and Blood Volume after Aneurysmal Subarachnoid Hemorrhage

Purpose: The aim of this prospective study was to evaluate changes of regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) in the first days after aneurysmal subarachnoid hemorrhage (SAH) in patients with and without unilateral cerebral vasospasm (CVS). Patients and Methods: In 48 patients perfusion-weighted magnetic resonance imaging (MRI) and digital subtraction angiography (DSA) were performed 5 ± 3 days after SAH. Local CVS was analyzed in the anterior cerebral artery (ACA) and middle cerebral artery (MCA) territory as well as in the basal ganglia. Each territory was compared with the corresponding contralateral area and SAH patients (control group) exhibiting no signs of CVS on follow-up DSA. Ratios of rCBV and rCBF of the vasospastic and the corresponding contralateral territory of local mild (11–33%), moderate (34–66%) and severe CVS (67–100%) were statistically evaluated using the Kruskal-Wallis test followed by Conover-Iman post-hoc test. Results: A significant decrease of rCBF under moderate CVS was seen in the ACA territory and in the basal ganglia in comparison to the control group of SAH patients without CVS (p < 0.05); furthermore, in the ACA territory rCBF significantly decreased under moderate CVS in comparison to mild CVS (p < 0.01). Comparison of rCBV in all three areas showed no significant differences in all grades of CVS. Conclusion: Regional CBV as an indicator of autoregulatory vasodilatation did not increase with higher CVS, suggesting an at least partially impaired autoregulation in the early phase after SAH. However, hemodynamic relevance of this impaired autoregulation might be dependent on the degree of CVS, the vascular territory, and the involvement of the microcirculation.