Early CT perfusion changes and blood-brain barrier permeability after aneurysmal subarachnoid hemorrhage

Early and delayed blood-brain barrier permeability predicts delayed cerebral ischemia and outcomes following aneurysmal subarachnoid hemorrhage

OBJECTIVES

This study aimed to monitor blood-brain barrier permeability within 24 h and during the delayed cerebral ischemia (DCI) time window (DCITW) spanning 4-14 days after aneurysmal subarachnoid hemorrhage (aSAH) and to investigate its correlation with both DCI occurrence and outcomes at three months.

METHODS

A total of 128 patients were stratified based on the DCI occurrence and three-month modified Rankin scale scores. Comparison of Ktrans at admission (admission Ktrans) and during DCITW (DCITW Ktrans) was conducted between DCI and non-DCI groups, as well as between groups with good and poor outcomes. Changes in Ktrans were also analyzed. Multivariate logistic regression analysis was performed to identify independent predictors of DCI and poor outcomes.

RESULTS

Admission Ktrans (0.58 ± 0.18 vs 0.47 ± 0.12, p = 0.002) and DCITW Ktrans (0.54 ± 0.19 vs 0.41 ± 0.14, p < 0.001) were significantly higher in the DCI group compared with the non-DCI group. Although both were higher in the poor outcome group than the good outcome group, the difference was not statistically significant at admission (0.53 ± 0.18 vs 0.49 ± 0.14, p = 0.198). Ktrans in the non-DCI group (0.47 ± 0.12 vs 0.41 ± 0.14, p = 0.004) and good outcome group (0.49 ± 0.14 vs 0.41 ± 0.14, p < 0.001) decreased significantly from the admission to DCITW. Multivariate analysis identified DCITW Ktrans and admission Ktrans as independent predictors of poor outcomes (OR = 1.73, 95%CI: 1.24-2.43, p = 0.001) and DCI (OR = 1.75, 95%CI: 1.25-2.44, p = 0.001), respectively.

CONCLUSION

Elevated Ktrans at admission is associated with the occurrence of DCI. Continuous monitoring of Ktrans from admission to DCITW can accurately identify reversible and irreversible changes and can predict outcomes at 3 months.

CLINICAL RELEVANCE STATEMENT

Ktrans measured with CT perfusion is a valuable tool for predicting both delayed cerebral ischemia and three-month outcomes following aneurysmal subarachnoid hemorrhage. Monitoring changes in Ktrans from admission to time window of delayed cerebral ischemia can guide treatment and management decisions for aneurysmal subarachnoid hemorrhage patients.

KEY POINTS

• Ktrans measured at admission and during the delayed cerebral ischemia time window (4-14 days) holds distinct clinical significance following aneurysmal subarachnoid hemorrhage. • Admission Ktrans serves as a predictor for delayed cerebral ischemia, while continuous assessment of Ktrans from admission to the delayed cerebral ischemia time window can predict three-month outcomes. • Monitoring Ktrans at different stages improves instrumental in enhancing decision-making and treatment planning for patients with aneurysmal subarachnoid hemorrhage.

Perfusion tomography in early follow-up of acute traumatic subdural hematoma: a case series

Perfusion Computed Tomography (PCT) is an alternative tool to assess cerebral hemodynamics during trauma. As acute traumatic subdural hematomas (ASH) is a severe primary injury associated with poor outcomes, the aim of this study was to evaluate the cerebral hemodynamics in this context. Five adult patients with moderate and severe traumatic brain injury (TBI) and ASH were included. All individuals were indicated for surgical evacuation. Before and after surgery, PCT was performed and cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) were evaluated. These parameters were associated with the outcome at 6 months post-trauma with the extended Glasgow Outcome Scale (GOSE). Mean age of population was 46 years (SD: 8.1). Mean post-resuscitation Glasgow coma scale (GCS) was 10 (SD: 3.4). Mean preoperative midline brain shift was 10.1 mm (SD: 1.8). Preoperative CBF and MTT were 23.9 ml/100 g/min (SD: 6.1) and 7.3 s (1.3) respectively. After surgery, CBF increase to 30.7 ml/100 g/min (SD: 5.1), and MTT decrease to 5.8s (SD:1.0), however, both changes don't achieve statistically significance (p = 0.06). Additionally, CBV increase after surgery, from 2.34 (SD: 0.67) to 2.63 ml/100 g (SD: 1.10), (p = 0.31). Spearman correlation test of postoperative and preoperative CBF ratio with outcome at 6 months was 0.94 (p = 0.054). One patient died with the highest preoperative MTT (9.97 s) and CBV (4.51 ml/100 g). CBF seems to increase after surgery, especially when evaluated together with the MTT values. It is suggested that the improvement in postoperative brain hemodynamics correlates to favorable outcome.

Elevated cortical blood flow insufficiency volume as a predictor of adverse outcomes in aneurysmal subarachnoid hemorrhage: a large prospective quantitative computed tomography perfusion study

PURPOSE

Early hypoperfusion changes exist in patients with aneurysmal subarachnoid hemorrhage (aSAH). We aimed to investigate a readily obtainable quantitative computed tomography perfusion (CTP) parameter that could assist in quickly identifying patients at risk of delayed cerebral ischemia (DCI) and poor 90-day functional outcomes on admission.

METHODS

We prospectively collected data between 2021.04 and 2022.12. Preoperative CTP data were post-processed using RAPID software. The cortical blood flow insufficiency (CBFI) was defined as Time-to-maximum > 4.0 s. Patients were categorized into four groups according to CBFI volume distribution. To minimize differences among the groups, we employed stabilized inverse probability of treatment weighting (sIPTW). The primary outcome was DCI and poor 90-day functional outcomes (modified Rankin Scale, 3-6) was the secondary outcome. Multivariable Cox or Logistic analysis were performed to estimate the association between CBFI volume and the study outcomes, both before and after sIPTW.

RESULTS

At baseline, the mean (SD) age of the 493 participants was 55.0 (11.8) years, and 299 (60.6%) were female. One hundred and seven participants with DCI and eighty-six participants with poor 90-day functional outcomes were identified. After sIPTW, CBFI volume demonstrated a significant association with DCI (Cox regression: Group 4 versus Group 1, HR 3.69, 95% CI 1.84-7.01) and poor 90-day functional outcomes (Logistic regression: Group 4 versus Group 1, OR 4.61, 95% CI 2.01-12.50).

CONCLUSION

In this study, an elevated preoperative CBFI volume was associated with adverse outcomes in aSAH patients. More well-designed studies are needed to confirm this association.

Blood Pressure Affects the Early CT Perfusion Imaging in Patients with aSAH Reflecting Early Disturbed Autoregulation

BACKGROUND

Early computed tomography perfusion (CTP) is frequently used to predict delayed cerebral ischemia following aneurysmatic subarachnoid hemorrhage (aSAH). However, the influence of blood pressure on CTP is currently controversial (HIMALAIA trial), which differs from our clinical observations. Therefore, we aimed to investigate the influence of blood pressure on early CTP imaging in patients with aSAH.

METHODS

We retrospectively analyzed the mean transit time (MTT) of early CTP imaging within 24 h after bleeding prior to aneurysm occlusion with respect to blood pressure shortly before or after the examination in 134 patients. We correlated the cerebral blood flow with the cerebral perfusion pressure in the case of patients with intracranial pressure measurement. We performed a subgroup analysis of good-grade (World Federation of Neurosurgical Societies [WFNS] I-III), poor-grade (WFNS IV-V), and solely WFNS grade V aSAH patients.

RESULTS

Mean arterial pressure (MAP) significantly correlated inversely with the mean MTT in early CTP imaging (R =  - 0.18, 95% confidence interval [CI] - 0.34 to - 0.01, p = 0.042). Lower mean blood pressure was significantly associated with a higher mean MTT. Subgroup analysis revealed an increasing inverse correlation when comparing WFNS I-III (R =  - 0.08, 95% CI - 0.31 to 0.16, p = 0.53) patients with WFNS IV-V (R =  - 0.2, 95% CI - 0.42 to 0.05, p = 0.12) patients, without reaching statistical significance. However, if only patients with WFNS V are considered, a significant and even stronger correlation between MAP and MTT (R =  - 0.4, 95% CI - 0.65 to 0.07, p = 0.02) is observed. In patients with intracranial pressure monitoring, a stronger dependency of cerebral blood flow on cerebral perfusion pressure is observed for poor-grade patients compared with good-grade patients.

CONCLUSIONS

The inverse correlation between MAP and MTT in early CTP imaging, increasing with the severity of aSAH, suggests an increasing disturbance of cerebral autoregulation with the severity of early brain injury. Our results emphasize the importance of maintaining physiological blood pressure values in the early phase of aSAH and preventing hypotension, especially in patients with poor-grade aSAH.

The value of early CT perfusion parameters for predicting delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis

Delayed cerebral ischemia (DCI) is a devastating complication of aneurysmal subarachnoid hemorrhage (aSAH). We aim to investigate the efficacy of early CT perfusion (CTP) parameters for predicting DCI in patients with aSAH. The search was conducted in five databases (PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, and China Biology Medicine database). Studies were reviewed by two independent authors, and the included studies were assessed for methodological quality. Fifteen studies with 882 participants were included for the final analysis. The meta-analysis of quantitative parameters showed that mean transit time represented the most valuable predictor when the calculation of the mean value was uniformed (MD 0.30 s, 95% CI: 0.10 to 0.49 s, P = 0.003). Semi-quantitative parameters using relative values or index scores were also widely used to minimize undue variations derived from patients, operators, machines, and software. Studies also demonstrated that these relative parameters had better predictive accuracy than corresponding absolute parameters. Perfusion thresholds in each study were incomparable, and the results warranted further validation. The best threshold for the prediction was 0.9 using the relative cerebral blood flow parameter (sensitivity 97% and specificity 89%). We conclude that CTP in the early phase is a promising tool for predicting DCI in aSAH patients. However, the parameters require standardization. Future studies with prospective, multi-centered design and large sample size are needed to validate the thresholds and optimize the parameters.

Whole-Brain Permeability Analysis on Admission Improves Prediction of Delayed Cerebral Ischemia Following Aneurysmal Subarachnoid Hemorrhage

PURPOSE

To evaluate the changes of blood-brain barrier permeability (BBBP) after aneurysmal subarachnoid hemorrhage (aSAH) and find out whether BBBP within 24 h after onset can further improve prediction of delayed cerebral ischemia (DCI).

METHODS

CT perfusion (CTP) was performed within 24 h after onset and in the DCI time window (DCITW). Whole brain average values of flow extraction product (mK^trans), qualitative and quantitative CTP parameters, and clinical data were compared between DCI and non-DCI groups. The changes of mK^trans were analysed using a Paired t test. Multivariate logistic regression analysis and ROC analyses were performed to identify predictors of DCI and evaluate the predictive performance.

RESULTS

One hundred and forty of 179 consecutive patients were included, 45 of whom (32%) developed DCI. mK^trans was higher in the DCI group both on admission and in the DCITW (P<0.001). mK^trans decreased significantly in the non-DCI group (P=0.003), but not in DCI group (P=0.285). Multivariate logistic regression analysis showed that mK^trans (OR=1.07, 95%CI: 1.03-1.11, P<0.001), World Federation of Neurosurgery Scale (OR=6.73, 95%CI: 1.09-41.41, P=0.040), Hunt-Hess grade (OR=0.16, 95%CI: 0.02-1.19, P=0.073), modified Fisher Score (OR=3.74, 95%CI: 1.30-10.75, P=0.014), and qualitative CTP (OR=4.31, 95%CI: 1.49-12.47, P=0.007) were independent predictors of DCI. The model with K^trans produced a larger AUC of 0.88 (95%CI: 0.81-0.95), with corresponding sensitivity and specificity of 84% and 86%, respectively.

CONCLUSION

BBBP measurement within 24 h after onset can improve the prediction of DCI. Early moderate BBB disruption may be reversible, whereas severe BBBP disruption indicates the risk of DCI.

Early Microcirculatory Hemodynamic Changes Are Correlated With Functional Outcomes at Discharge in Patients With Aneurysmal SAH

Purpose

The technique of color-coding blood flow analysis was used to explore the correlation between the microcirculatory hemodynamic changes on digital subtraction angiography (DSA) images in patients with aneurysmal subarachnoid hemorrhage (SAH) at the early stage and functional outcomes at discharge.

Methods

Data of 119 patients who underwent DSA examination due to SAH were retrospectively analyzed. The following hemodynamic parameters of the four region of interests (ROIs) [an ophthalmic segment of the internal carotid artery (ICA), frontal and parietal lobe, and superior sagittal sinus] were analyzed: the time-to-peak (TTP), the area under the curve (AUC), the full width at half maximum (FWHM), mean transit time (MTT), and circulation time. Multifactor regression analysis was performed to explore the correlation between the hemodynamic parameters and functional outcomes in patients at discharge.

Results

Of 119 patients with SAH, good and poor outcomes were found in 83 (69.7%) and 36 (30.3%) patients, respectively. The hemodynamic parameters including the FWHM, relative TTP (rTTP), and circulation time were significantly correlated with the Hunt–Hess grade (p < 0.005, p = 0.03, and p < 0.005) and the World Federation of Neurological Societies Scale grade (p < 0.005, p = 0.02, and p = 0.01). The FWHM was significantly prolonged with the increase of modified Fisher grade (p = 0.02). The multifactor analysis showed that the FWHM [odds ratio (OR) 17.56, 95% CI: 1.13–272.03, p = 0.04] was an independent risk factor predicting the functional outcomes in patients at discharge.

Conclusion

The technique of color-coding blood flow analysis could be suitable for the qualified evaluation of disease conditions at an early stage of SAH as well as the prediction of outcomes.

MTT Heterogeneity in Perfusion CT Imaging as a Predictor of Outcome after Aneurysmal SAH

BACKGROUND AND PURPOSE

Impairment of tissue oxygenation caused by inhomogeneous microscopic blood flow distribution, the so-called capillary transit time heterogeneity, is thought to contribute to delayed cerebral ischemia after aneurysmal SAH but has so far not been systematically evaluated in patients. We hypothesized that heterogeneity of the MTT, derived from CTP parameters, would give insight into the clinical course of patients with aneurysmal SAH and may identify patients at risk of poor outcome.

MATERIALS AND METHODS

We retrospectively analyzed the heterogeneity of the MTT using the coefficient of variation in CTP scans from 132 patients. A multivariable logistic regression model was used to model the dichotomized mRS outcome. Linear regression was used to eliminate variables with high linear dependence. T tests were used to compare the means of 2 groups. Furthermore, the time of the maximum coefficient of variation for MTT after bleeding was evaluated for correlation with the mRS after 6 months.

RESULTS

On average, each patient underwent 5.3 CTP scans during his or her stay. Patients with high coefficient of variation for MTT presented more often with higher modified Fisher (P = .011) and World Federation of Neurosurgical Societies grades (P = .014). A high coefficient of variation for MTT at days 3-21 after aneurysmal SAH correlated significantly with a worse mRS score after 6 months (P = .016). We found no correlation between the time of the maximum coefficient of variation for MTT after bleeding and the patients' outcomes after 6 months (P = .203).

CONCLUSIONS

Heterogeneity of MTT in CTP after aneurysmal SAH correlates with the patients' outcomes. Because the findings are in line with the pathophysiologic concept of the capillary transit time heterogeneity, future studies should seek to verify the coefficient of variation for MTT as a potential imaging biomarker for outcome.

Blood-brain barrier permeability imaging as a predictor for delayed cerebral ischaemia following subarachnoid haemorrhage. A narrative review

BACKGROUND

Aneurysmal subarachnoid haemorrhage is associated with significant morbidity and mortality due to the myriad of complications contributing to early brain injury and delayed cerebral ischaemia. There is increasing interest in the exploration of the association between blood-brain barrier integrity and risks of delayed cerebral ischaemia and poor outcomes. Despite recent advances in cerebral imaging, radiographic imaging of blood-brain barrier disruption, as a biomarker for outcome prediction, has not been adopted in clinical practice.

METHODS

We performed a narrative review by searching for articles describing molecular changes or radiological identification of changes in BBB permeability following subarachnoid haemorrhage (SAH) on MEDLINE. Preclinical studies were analysed if reported structural changes and clinical studies were included if they investigated for radiological markers of BBB disruption and its correlation with delayed cerebral ischaemia.

RESULTS

There is ample preclinical evidence to suggest that there are structural changes in BBB permeability following SAH. The available clinical literature has demonstrated correlations between permeability imaging and outcomes following aneurysmal subarachnoid haemorrhage (aSAH).

CONCLUSION

Radiological biomarkers offer a potential non-invasive prognostication tool and may also allow early identifications of patients who may be at risk of DCI.

The Updated Role of the Blood Brain Barrier in Subarachnoid Hemorrhage: From Basic and Clinical Studies

Subarachnoid hemorrhage (SAH) is a type of hemorrhagic stroke associated with high mortality and morbidity. The blood-brain-barrier (BBB) is a structure consisting primarily of cerebral microvascular endothelial cells, end feet of astrocytes, extracellular matrix, and pericytes. Post-SAH pathophysiology included early brain injury and delayed cerebral ischemia. BBB disruption was a critical mechanism of early brain injury and was associated with other pathophysiological events. These pathophysiological events may propel the development of secondary brain injury, known as delayed cerebral ischemia. Imaging advancements to measure BBB after SAH primarily focused on exploring innovative methods to predict clinical outcome, delayed cerebral ischemia, and delayed infarction related to delayed cerebral ischemia in acute periods. These predictions are based on detecting abnormal changes in BBB permeability. The parameters of BBB permeability are described by changes in computed tomography (CT) perfusion and magnetic resonance imaging (MRI). K_ep seems to be a stable and sensitive indicator in CT perfusion, whereas K^trans is a reliable parameter for dynamic contrast-enhanced MRI. Future prediction models that utilize both the volume of BBB disruption and stable parameters of BBB may be a promising direction to develop practical clinical tools. These tools could provide greater accuracy in predicting clinical outcome and risk of deterioration. Therapeutic interventional exploration targeting BBB disruption is also promising, considering the extended duration of post-SAH BBB disruption.

Assessment of tissue permeability by early CT perfusion as a surrogate parameter for early brain injury after subarachnoid hemorrhage

OBJECTIVE

The severity of early brain injury (EBI) after aneurysmal subarachnoid hemorrhage (aSAH) correlates with delayed cerebral ischemia (DCI) and outcome. A disruption of the blood-brain barrier is part of EBI pathophysiology. The aim of this study was to assess tissue permeability (PMB) by CT perfusion (CTP) in the acute phase after aSAH and its impact on DCI and outcome.

METHODS

CTP was performed on day 3 after aSAH. Qualitative and quantitative analyses of all CTP parameters, including PMB, were performed. The areas with increased PMB were documented. The value of an early PMB increase as a predictor of DCI and outcome according to the modified Rankin Scale (mRS) grade 3 to 24 months after aSAH was assessed. Possible associations of increased PMB with the Subarachnoid Hemorrhage Early Brain Edema Score (SEBES) and with early perfusion deficits, as radiographic EBI markers, were evaluated.

RESULTS

A total of 69 patients were enrolled in the study. An increased PMB on early CTP was detected in 10.1% (7/69) of all patients. A favorable outcome (mRS grade ≤ 2) occurred in 40.6% (28/69) of all patients. DCI was detected in 25% (17/69) of all patients. An increased PMB was a predictor of DCI (logistic regression, p = 0.03) but not of outcome (logistic regression, p = 0.40). The detection of increased PMB predicted DCI with a sensitivity of 25%, a specificity of 94%, a positive predictive value of 57%, and a negative predictive value of 79% (chi-square test p = 0.03). Early perfusion deficits were seen in 68.1% (47/69) of the patients, a finding that correlated with DCI (p = 0.005) but not with the outcome. No correlation was found between the SEBES and increased PMB.

CONCLUSIONS

Changes in PMB can be detected by early CTP after aSAH, which correlates with DCI. Future studies are needed to evaluate the time course of PMB changes and their interaction with therapeutic measures.

TNF-R1 Correlates with Cerebral Perfusion and Acute Ischemia Following Subarachnoid Hemorrhage

BACKGROUND

Early cerebral hypoperfusion and ischemia occur after subarachnoid hemorrhage (SAH) and influence clinical prognosis. Pathophysiological mechanisms possibly involve inflammatory mediators. TNF-α has been associated with complications and prognosis after SAH. We investigated the relation of perfusion parameters and ischemic lesions, with levels of TNF-α main receptor, TNF-R1, after SAH, and their association with prognosis.

METHODS

We included consecutive SAH patients admitted within the first 72 h of SAH onset. Blood samples were simultaneously collected from a peripheral vein and from the parent artery of the aneurysm. Levels of TNF-R1 were measured using ELISA (R&D Systems Inc., USA). CT perfusion and MRI studies were performed in the first 72 h. Correlation and logistic regression analysis were used to identify outcome predictors.

RESULTS

We analyzed 41 patients. Increased levels of TNF-R1 correlated with increased T_max (arterial: r = -0.37, p = 0.01) and prolonged MTT (arterial: r = 0.355, p = 0.012; venous: r = 0.306, p = 0.026). Increased levels of both arterial and venous TNF-R1 were associated with increased number of lesions on DWI (p = 0.006). In multivariate analysis, venous TNFR1 levels > 1742.2 pg/mL (OR 1.78; 95%CI 1.18-2.67; p = 0.006) and DWI lesions (OR 14.01; 95%CI 1.19-165.3; p = 0.036) were both independent predictors of poor outcome (mRS ≥ 3) at 6 months.

CONCLUSION

Increased levels of TNF-R1 in arterial and venous blood correlate with worse cerebral perfusion and with increased burden of acute ischemic lesions in the first 72 h after SAH. Venous levels of TNF-R1 and DWI lesions were associated with poor outcome at 6 months. These results highlight the pathophysiological role of TNF-α pathways in SAH and suggest a possible role of combined imaging and laboratorial markers in determining prognosis in acute SAH.

Imaging predictors of outcome in acute spontaneous subarachnoid hemorrhage: a review of the literature

Spontaneous subarachnoid hemorrhage (SAH) accounts for about 5% of strokes, but has a very high morbidity and mortality. Many survivors are left with important cognitive impairment and are severely incapacitated. Prediction of complications such as vasospasm and delayed cerebral ischemia, and of clinical outcome after SAH, is challenging. Imaging studies are essential in the initial evaluation of SAH patients and are increasingly relevant in assessing for complications and prognosis. In this article, we reviewed the role of imaging studies in evaluating early brain injury and predicting complications as well as clinical and neuropsychological prognosis after acute SAH.

Prospective Multicenter Study of Changes in MTT after Aneurysmal SAH and Relationship to Delayed Cerebral Ischemia in Patients with Good- and Poor-Grade Admission Status

BACKGROUND AND PURPOSE

Patients with aneurysmal SAH and good clinical status at admission are considered at a lower risk for delayed cerebral ischemia. Prolonged MTT may be associated with an increased risk. It is unclear whether this is dependent on clinical status. Our purpose was to determine whether increased MTT within 3 days of aneurysmal SAH compared with baseline is associated with a higher risk of delayed cerebral ischemia in patients with good (World Federation of Neurosurgical Societies I-III) versus poor (World Federation of Neurosurgical Societies IV-V) admission status.

MATERIALS AND METHODS

This prolonged MTT was a multicenter, prospective cohort investigation of 87 patients with aneurysmal SAH. MTT was measured at admission before aneurysm treatment (MTT1) and following repair (MTT2) within 3 days of admission; MTT_diff was calculated as the difference between MTT2 and MTT1. Changes in MTT across time were assessed with repeated measures analyses. Risk of delayed cerebral ischemia or death was determined with multivariate logistic regression analysis.

RESULTS

In patients with a good grade (n = 49), MTT was prolonged in patients who developed delayed cerebral ischemia, with MTT_diff significantly greater (0.82 ± 1.5) compared with those who did not develop delayed cerebral ischemia (-0.14 ± 0.98) (P = .03). Prolonged MTT was associated with a significantly higher risk of delayed cerebral ischemia or death (OR = 3.1; 95% CI, 1.3-7.4; P = .014) on multivariate analysis. In patients with poor grades (n = 38), MTT_diff was not greater in patients who developed delayed cerebral ischemia; MTT1 was significantly prolonged compared with patients with a good grade.

CONCLUSIONS

Patients in good clinical condition following aneurysmal SAH but with increasing MTT in the first few days after aneurysmal SAH are at high risk of delayed cerebral ischemia and warrant close clinical monitoring.

Prediction of outcome after aneurysmal subarachnoid haemorrhage using data from patient admission

OBJECTIVES

The pathogenesis leading to poor functional outcome after aneurysmal subarachnoid haemorrhage (aSAH) is multifactorial and not fully understood. We evaluated a machine learning approach based on easily determinable clinical and CT perfusion (CTP) features in the course of patient admission to predict the functional outcome 6 months after ictus.

METHODS

Out of 630 consecutive subarachnoid haemorrhage patients (2008-2015), 147 (mean age 54.3, 66.7% women) were retrospectively included (Inclusion: aSAH, admission within 24 h of ictus, CTP within 24 h of admission, documented modified Rankin scale (mRS) grades after 6 months. Exclusion: occlusive therapy before first CTP, previous aSAH, CTP not evaluable). A random forests model with conditional inference trees was optimised and trained on sex, age, World Federation of Neurosurgical Societies (WFNS) and modified Fisher grades, aneurysm in anterior vs. posterior circulation, early external ventricular drainage (EVD), as well as MTT and T_max maximum, mean, standard deviation (SD), range, 75th quartile and interquartile range to predict dichotomised mRS (≤ 2; > 2). Performance was assessed using the balanced accuracy over the training and validation folds using 20 repeats of 10-fold cross-validation.

RESULTS

In the final model, using 200 trees and the synthetic minority oversampling technique, median balanced accuracy was 84.4% (SD 0.7) over the training folds and 70.9% (SD 1.2) over the validation folds. The five most important features were the modified Fisher grade, age, MTT range, WFNS and early EVD.

CONCLUSIONS

A random forests model trained on easily determinable features in the course of patient admission can predict the functional outcome 6 months after aSAH with considerable accuracy.

KEY POINTS

• Features determinable in the course of admission of a patient with aneurysmal subarachnoid haemorrhage (aSAH) can predict the functional outcome 6 months after the occurrence of aSAH. • The top five predictive features were the modified Fisher grade, age, the mean transit time (MTT) range from computed tomography perfusion (CTP), the WFNS grade and the early necessity for an external ventricular drainage (EVD). • The range between the minimum and the maximum MTT may prove to be a valuable biomarker for detrimental functional outcome.

Changes in Cerebral Perfusion with Induced Hypertension in Aneurysmal Subarachnoid Hemorrhage: A Pilot and Feasibility Study

BACKGROUND

The effects of induced hypertension (IH) on cerebral perfusion after subarachnoid hemorrhage (SAH) are unclear. The objectives of this investigation are to: (1) determine whether there are differences in cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) measured with computed tomography perfusion (CTP) before and after IH; (2) evaluate differences in the presence of infarction and clinical outcome between patients with and without IH.

METHODS

We performed a retrospective cohort analysis of 25 aneurysmal SAH patients. IH was initiated as per the standard institutional protocol when patients showed clinical symptoms of delayed cerebral ischemia (DCI). Differences in CBF, CBV, and MTT between early (<72 h after aneurysm rupture) and late (7-10 days after aneurysm rupture) CTP were quantified in patients with (n = 13) and without IH (n = 12). Outcome measures included cerebral infarction and clinical outcome at 3 months.

RESULTS

Early MTT was significantly greater in the IH group compared to the no-IH group. There was no difference in early or late CBV or CBF between the two groups. In patients that received IH, there was a significant decrease in MTT between the early (7.0 ± 1.2 s) and late scans (5.8 ± 1.6 s; p = 0.005). There was no difference in the incidence of infarction (5/13 vs. 2/11) or poor outcome (3/11 vs. 6/13) between the IH and no-IH groups, respectively (p > 0.05).

CONCLUSIONS

Elevated MTT is a significant factor for the development of DCI in patients eventually requiring IH therapy and is improved by IH treatment. Therapies to prevent DCI and improve clinical outcome may need to be initiated earlier, when cerebral perfusion abnormalities are first identified.

Comparison of cerebral perfusion in perimesencephalic subarachnoid hemorrhage and aneurysmal subarachnoid hemorrhage

PURPOSE

Perimesencephalic hemorrhage (PMH) is a benign subtype of nonaneurysmal subarachnoid hemorrhage (SAH). We aimed to investigate if cerebral perfusion in PMH is less affected than in aneurysmal SAH (aSAH).

METHODS

From a prospective cohort of 80 patients with spontaneous SAH, we included PMH patients (n = 15) and selected aSAH patients (n = 39) with similar clinical grade at admission (World Federation of Neurosurgeons Scale-WFNS I/II). Computed tomography (CT) perfusion was performed at < 72 h and/or at 8-10 days. Cerebral perfusion parameter values were compared between groups with nonparametric tests. Subgroup analyses compared PMH and aSAH patients stratified according to aneurysmal location (anterior or posterior circulation) and blood burden (Fisher grade).

RESULTS

At < 72 h, no significant differences in perfusion parameters were found between PMH and aSAH patients. At 8-10 days, PMH patients had lower MTT than aSAH patients, and a trend for higher CBF. PMH patients had higher CBF and CBV at < 72 h when compared to posterior circulation aSAH patients. When compared to aSAH patients with similar blood burden, PMH patients had higher CBF and lower MTT at < 72 h, and lower MTT at 8-10 days.

CONCLUSION

PMH patients had better cerebral perfusion compared to patients with aSAH, particularly during the vasospasm time window. After stratifying for the amount of blood, PMH patients also had better cerebral perfusion in the first 72 h after SAH. These results are in line with the better clinical presentation and prognosis of PMH, and possibly with a different etiology.

The Pathophysiology of Delayed Cerebral Ischemia

Subarachnoid hemorrhage (SAH) affects 30,000 people in the Unites States alone each year. Delayed cerebral ischemia occurs days after subarachnoid hemorrhage and represents a potentially treatable cause of morbidity for approximately one-third of those who survive the initial hemorrhage. While vasospasm has been traditionally linked to the development of cerebral ischemia several days after subarachnoid hemorrhage, emerging evidence reveals that delayed cerebral ischemia is part of a much more complicated post-subarachnoid hemorrhage syndrome. The development of delayed cerebral ischemia involves early arteriolar vasospasm with microthrombosis, perfusion mismatch and neurovascular uncoupling, spreading depolarizations, and inflammatory responses that begin at the time of the hemorrhage and evolve over time, culminating in cortical infarction. Large-vessel vasospasm is likely a late contributor to ongoing injury, and effective treatment for delayed cerebral ischemia will require improved detection of critical early pathophysiologic changes as well as therapeutic options that target multiple related pathways.