Role of microcirculatory impairment in delayed cerebral ischemia and outcome after aneurysmal subarachnoid hemorrhage

Early brain injury (EBI) is considered an important cause of morbidity and mortality after aneurysmal subarachnoid hemorrhage (aSAH). As a factor in EBI, microcirculatory dysfunction has become a focus of interest, but whether microcirculatory dysfunction is more important than angiographic vasospasm (aVS) remains unclear. Using data from 128 cases, we measured the time to peak (TTP) in several regions of interest on digital subtraction angiography. The intracerebral circulation time (iCCT) was obtained between the TTP in the ultra-early phase (the baseline iCCT) and in the subacute phase and/or at delayed cerebral ischemia (DCI) onset (the follow-up iCCT). In addition, the difference in the iCCT was calculated by subtracting the baseline iCCT from the follow-up iCCT. Univariate analysis showed that DCI was significantly increased in those patients with a prolonged baseline iCCT, prolonged follow-up iCCT, increased differences in the iCCT, and with severe aVS. Poor outcome was significantly increased in patients with prolonged follow-up iCCT and increased differences in the iCCT. Multivariate analysis revealed that increased differences in the iCCT were a significant risk factor that increased DCI and poor outcome. The results suggest that the increasing microcirculatory dysfunction over time, not aVS, causes DCI and poor outcome after aneurysmal aSAH.