gms | German Medical Science

Objective: Early brain injury (EBI) after aneurysmal subarachnoid hemorrhage (aSAH) correlates with delayed cerebral ischemia (DCI) and clinical outcome. The assessment of EBI allows the identification of blood brain barrier and disturbed autoregulation leading to cerebral edema are part of EBI-pathophysiology after aSAH. The aim of this study was to assess the tissue permeability by CT perfusion (CTP) in the acute phase after aSAH as possible surrogate marker of EBI.

Methods: Whole brain CTP was performed in the acute phase (day 2-4) after aSAH. The tissue permeability was measured in both hemispheres and areas with increased permeability were documented. The permeability measurements were than correlated with the occurrence of DCI and with clinical outcome according to modified Rankin scale (mRS) 3-24 months after ictus. Early perfusion defictis after qualitative and quantitative analysis of CTP parameters (CBF, CBV, MTT, TTP, TTS and TTD) were documented. The recently published Subarachnoid Hemorrhage Early Brain Edema Score (SEBES) (Ahn et al. Neurosurgery 2017) was used as a radiographic marker of EBI severity based on initial CT scan. A correlation analysis was performed to evaluate possible association of increased tissue permeability and early perfusion deficits with SEBES.

Results: A total of 72 patients with high Hunt&Hess grade (4-5) in 63% and high Fisher grade (3-4) in 96% were prospectively enrolled in the study. DCI developed in 24% (17/72). A favorable outcome (mRS≤3) was found in 56% (39/72) of all patients. An increased permeability on early CTP was found in 10% (7/72) of all patients. Early perfusion deficits were seen in 68% (49/72) of all patients. The presence of increased permeability correlated significantly with the occurrence of DCI (linear regression, p=0.03) but not with outcome. We found no significant correlation between the SEBES and the increased tissue permeability or early perfusion deficits.

Conclusion: Changes in tissue permeability can be detected by early CTP in the acute phase after aSAH, which correlate with DCI. While perfusion deficits are often seen in the early phase after aSAH, changes of tissue permeability seem to occur less frequent in this time period after the bleeding event. Future studies are needed to evaluate the time course of tissue permeability changes and their interaction with therapeutic measures.