Quantification of Cerebral Edema After Subarachnoid Hemorrhage

Impact of Microcirculatory Dysfunction on Persistent Global Cerebral Edema After Aneurysmal Subarachnoid Hemorrhage: An Age-Stratified Analysis

BACKGROUND

Microcirculatory dysfunction is one of the most important pathophysiology mechanisms of global cerebral edema (GCE) after aneurysmal subarachnoid hemorrhage (aSAH). Data regarding the impact of microcirculatory dysfunction on persistent GCE following aSAH are currently lacking. The aim of our study was to investigate whether microcirculatory dysfunction is correlated with persistent GCE in patients with aSAH across different age groups.

METHODS

The study was conducted in Beijing Tiantan Hospital from October 2020 to July 2023. Patients with aSAH who underwent computed tomographic perfusion (CTP) within 24 h after ictus were enrolled prospectively. The difference value of arteriovenous peak time (DV), which serves as an indicator of microcirculatory impairment, was derived from the time-density curve of CTP. Persistent GCE was defined as selective sulcal volume ≤ 11.3 mL at both admission and 7 ± 1 days after ictus. Age-stratified multivariable analyses were applied to identify the association between microcirculatory dysfunction and persistent GCE.

RESULTS

A total of 390 patients with aSAH were enrolled; the mean age was 56.5 ± 12.1 years old, and 245 (65.1%) patients were female. On multivariable analysis, prolonged DV was significantly associated with increased risk of persistent GCE after aSAH in patients older than 60 years (adjusted odds ratio 1.350, 95% confidence interval 1.025-1.778), whereas this similar independent association was not observed in patients younger than 60 years after adjusting for confounding factors (adjusted odds ratio 1.002, 95% confidence interval 0.817-1.229).

CONCLUSIONS

An age-dependent association between microcirculatory dysfunction and increased risk of persistent GCE following aSAH was found, which offers promising insight into future research to investigate tailored treatments across different ages.

Early Microcirculatory Dysfunction on Perfusion CT Is Related to Prognosis After Aneurysmal Subarachnoid Hemorrhage

Microcirculatory dysfunction is an important pathophysiology mechanism of early brain injury after aneurysmal subarachnoid hemorrhage (aSAH), which contributes to poor outcomes. The study was performed in Beijing Tiantan Hospital from October 2020 to July 2023. Patients with aSAH who underwent computed tomographic perfusion (CTP) within 24 h after ictus were enrolled prospectively. The peak time of arterial inflow (PTA), peak time of venous outflow (PTV), total venous outflow time (TVT), and difference value of arteriovenous peak time (DV) were collected from the time-density curve of CTP. Primary outcome was 3-month unfavorable functional outcome (modified Rankin Scale score of 4-6). Secondary outcomes included 3-month all-cause death and delayed cerebral ischemia. Multivariable logistic regression analysis and restricted cubic splines were performed to explore the relationship between cerebral hemodynamic parameters and outcomes. We also assessed the prognostic performance of incorporating hemodynamic parameters into previous nomogram models for 3-month poor clinical outcomes. A total of 612 patients were enrolled, among whom the mean age was 56.9 ± 12.3 years old and 391 (63.9%) were female. On multivariable analysis, prolonged TVT could significantly predict 3-month poor functional outcome (adjusted OR 1.074, 95%CI 1.013-1.139), while prolonged PTA was an independent predictor of 3-month all-cause death (adjusted OR 1.293, 95%CI 1.099-1.521). The addition of TVT or PTA to previous nomogram models led to improvements in C-statistics, net reclassification (NRI), and integrated discrimination improvement (IDI). Our study underscores the vital role of arterial inflow and venous outflow in sustaining microcirculation during the acute phase after aSAH, thereby offering new directions for future investigations into therapeutic targets.

Update on Strategies to Reduce Early Brain Injury after Subarachnoid Hemorrhage

PURPOSE OF REVIEW

Early brain injury (EBI) after aneurysmal subarachnoid hemorrhage (SAH) is the most influential clinical determinant of outcomes. Despite significant advances in understanding of the pathophysiology of EBI, currently no treatments to target EBI have been developed. This review summarizes recent advances in EBI research over the past five years with a focus on potential therapeutic targets.

RECENT FINDINGS

Mechanism-specific translational studies are converging on several pathophysiologic pathways: improved antioxidant delivery and the Sirt1/Nrf2 pathway for reactive oxygen species; NLRP3 inflammasome and microglial polarization for inflammation; and the PI3K/Akt pathway for apoptosis. Recently identified mechanistic components, such as microcirculatory failure and ferroptosis, need particular attention. Clinical studies developing radiographic markers and mechanism-specific, biofluid markers are attempting to bridge the translational therapeutic gap. There has been an exponential growth in EBI research. Further clinical studies which address specific pathophysiology mechanisms need to be performed to identify novel therapeutic approaches.

Quantification of blood and CSF volume to predict outcome after aneurysmal subarachnoid hemorrhage

This study aimed to describe the relationship between blood and CSF volumes in different compartments on baseline CT after aSAH, assess if they independently predict long-term outcome, and explore their interaction with age. CT scans from patients participating in a prospective multicenter randomized controlled trial of patients with aSAH were segmented for blood and CSF volumes. The primary outcomes were the mRS, and the Subarachnoid Hemorrhage Outcome Tool (SAHOT) at day 28 and 180. Univariate regressions were conducted to identify significant predictors of poor outcomes, followed by principal component analysis to explore correlations between imaging variables and WFNS. A multivariate predictive model was then developed and optimized using stepwise regression. CT scans from 97 patients with a median delay from symptom onset of 271 min (131-547) were analyzed. Univariate analysis showed only WFNS, and total blood volume (TBV) were significant predictors of both short and long-term outcome with WFNS more predictive of mRS and TBV more predictive of SAHOT. Principal component analysis showed strong dependencies between the imaging predictors. Multivariate ordinal regression showed models with WFNS alone were most predictive of day 180 mRS and models with TBV alone were most predictive of SAHOT. TBV was the most significant measured imaging predictor of poor long-term outcome after aSAH. All these imaging predictors are correlated, however, and may have multiple complex interactions necessitating larger datasets to detect if they provide any additional predictive value for long-term outcome.

Increased brain volume in the early phase of aneurysmal subarachnoid hemorrhage leads to delayed cerebral ischemia

Objective

To investigate the correlation between the swelling rate of brain volume within the first 48 h after aneurysmal subarachnoid hemorrhage and the subsequent development of delayed cerebral ischemia.

Methods

A retrospective analysis was conducted on patients with spontaneous aneurysmal subarachnoid hemorrhage admitted to the Neurosurgery Intensive Care Unit of the First Affiliated Hospital of Chongqing Medical University between January 2020 and January 2023. The clinical data, treatment outcomes, and imaging data were analyzed. Brain volume was evaluated using 3D-Slicer software at two time points post-hemorrhage: within the first 24 h and between 24 and 48 h. The swelling rate of brain volume was defined as the ratio of the absolute difference between two measurements to the smaller of values. Patients were categorized into two groups based on established diagnostic criteria of delayed cerebral ischemia. Univariate and multivariate logistic regression analyses were performed to identify factors influencing delayed cerebral ischemia.

Results

A total of 140 patients were enrolled in this study. 46 patients experienced delayed cerebral ischemia after bleeding. The swelling rate of brain volume was larger in the DCI group (10.66 ± 8.45) compared to the non-DCI group (3.59 ± 2.62), which showed a statistically significant difference. Additionally, advanced age, smoking history, history of hypertension, loss of consciousness, poor Hunt-Hess grade, high mFisher score, brain volume within 24 h, and IVH were also statistically different between the two groups. Multivariate logistic regression analysis revealed that the swelling rate of brain volume was an independent risk factor for DCI with adjusting the advanced age, smoking history, history of hypertension, poor Hunt-Hess grade, high mFisher score, brain volume within 24 h, and IVH.

Conclusion

Brain volume significantly increased in patients with aneurysmal subarachnoid hemorrhage during the early phase (within 48 h post-onset). The larger swelling rate of brain volume is an independent risk factor for the development of delayed cerebral ischemia, and it may hold significant predictive value for the incidence of delayed cerebral ischemia.

Emergent Management of Spontaneous Subarachnoid Hemorrhage

OBJECTIVE

Spontaneous subarachnoid hemorrhage (SAH) carries high morbidity and mortality rates, and the emergent management of this disease can make a large impact on patient outcome. The purpose of this article is to provide a pragmatic overview of the emergent management of SAH.

LATEST DEVELOPMENTS

Recent trials have influenced practice around the use of antifibrinolytics, the timing of aneurysm securement, the recognition of cerebral edema and focus on avoiding a lower limit of perfusion, and the detection and prevention of delayed cerebral ischemia. Much of the acute management of SAH can be protocolized, as demonstrated by two updated guidelines published by the American Heart Association/American Stroke Association and the Neurocritical Care Society in 2023. However, the gaps in evidence lead to clinical equipoise in some aspects of critical care management.

ESSENTIAL POINTS

In acute management, there is an urgency to differentiate the etiology of SAH and take key emergent actions including blood pressure management and coagulopathy reversal. The critical care management of SAH is similar to that of other acute brain injuries, with the addition of detecting and treating delayed cerebral ischemia. Strategies for the detection and treatment of delayed cerebral ischemia are limited by disordered consciousness and may be augmented by monitoring and imaging technology.

Schizandrin A attenuates early brain injury following subarachnoid hemorrhage through suppressing neuroinflammation

BACKGROUND

Early brain injury (EBI) is the vital factor in determining the outcome of subarachnoid hemorrhage (SAH). Schizandrin A (Sch A), the bioactive ingredient extracted from Schisandra chinensis, has been proved to exert beneficial effects in multiple human diseases. However, the effect of Sch A on SAH remains unknown. The current study was designed to explored role and mechanism of Sch A in the pathophysiological process of EBI following SAH.

METHOD

A total of 74 male C57BL/6 J mice were subjected to endovascular perforation to establish the SAH model. Different dosages of Sch A were administrated post-modeling. The post-modeling assessments included neurological test, brain water content, RT-PCR, immunofluorescence, Nissl staining. Oxygenated hemoglobin was introduced into microglia to establish a SAH model in vitro.

RESULT

Sch A significantly alleviated SAH-induced brain edema and neurological impairment. Moreover, application of Sch A remarkably inhibited SAH-induced neuroinflammation, evidenced by the decreased microglial activation and downregulated TNF-α, IL-1β and IL-6 and expression. Additionally, Sch A, both in vivo and in vitro, protected neurons against SAH-induced inflammatory injury. Mechanismly, administration of Sch A inhibited miR-155/NF-κB axis and attenuated neuroinflammation, as well as alleviating neuronal injury.

CONCLUSION

Our data suggested that Sch A could attenuated EBI following SAH via modulating neuroinflammation. The anti-inflammatory effect was exerted, at least partly through the miR-155/NF-κB axis, which may shed light on a possible therapeutic target for SAH.

Lower Serum Iron Level Predicts Postoperative Global Cerebral Edema Following Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Iron plays an important role in neuronal injury and edema formation after intracranial hemorrhage. However, the role of serum iron in aneurysmal subarachnoid hemorrhage (aSAH) is yet to be well-established. This study aims to identify whether serum iron could predict postoperative global cerebral edema (GCE) and poor outcome in aSAH.

METHODS

847 patients' aSAH clinical data were retrospectively collected at the First Affiliated Hospital of Fujian Medical University. Data on demographics, clinical characteristics, and laboratory values were collected and analyzed through univariate and multivariate analyses. Propensity score matching (PSM) analysis was performed to balance the baseline differences between the groups.

RESULTS

The incidence of high-grade global cerebral edema (H-GCE) following aSAH was 12.99% (110/847). Serum iron levels [odds ratio (OR) = 1.143; 95% confidence interval (CI), (1.097-1.191); p < 0.001] were associated with the occurrence of H-GCE following aSAH in the univariate analysis. This association remained statistically significant even after adjusting for other variables in the multivariate model, with serum iron having an OR of 1.091 (95% CI, 1.043-1.141; p < 0.001) for GCE. After 1:1 PSM, serum iron levels ≤ 10.7 µmol/L remained a significant independent predictor of GCE (p = 0.002). The receiver operating characteristic (ROC) curve analysis determined that a serum iron cut-off value of ≤ 10.7 µmol/L was optimal for predicting H-GCE [Areas under the ROC curves (AUC) = 0.701, 95% CI, (0.669-0.732), p < 0.001; sensitivity, 67.27%; specificity, 63.77%] in patients with aSAH. Additionally, a trend was observed in which higher Hunt-Hess grades (HH grade) were associated with lower serum iron levels, and higher modified Fisher grades (mFisher grade) were associated with lower serum iron levels. In addition, the serum iron level was also associated with a 3-month functional neurological outcome (p < 0.001).

CONCLUSIONS

The results of this study indicate that a decreased serum iron level serves as a clinically significant biomarker for the prediction of postoperative GCE and a poor outcome at 3-months in patients with aSAH.

Early Brain Injury After Subarachnoid Hemorrhage: Incidence and Mechanisms

Aneurysmal subarachnoid hemorrhage is a devastating condition causing significant morbidity and mortality. While outcomes from subarachnoid hemorrhage have improved in recent years, there continues to be significant interest in identifying therapeutic targets for this disease. In particular, there has been a shift in emphasis toward secondary brain injury that develops in the first 72 hours after subarachnoid hemorrhage. This time period of interest is referred to as the early brain injury period and comprises processes including microcirculatory dysfunction, blood-brain-barrier breakdown, neuroinflammation, cerebral edema, oxidative cascades, and neuronal death. Advances in our understanding of the mechanisms defining the early brain injury period have been accompanied by improved imaging and nonimaging biomarkers for identifying early brain injury, leading to the recognition of an elevated clinical incidence of early brain injury compared with prior estimates. With the frequency, impact, and mechanisms of early brain injury better defined, there is a need to review the literature in this area to guide preclinical and clinical study.

Role of the Subarachnoid Hemorrhage Early Brain Edema Score in the Management of Decompressive Craniectomy for Poor-Grade Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

The Subarachnoid Hemorrhage Early Brain Edema Score (SEBES) is a radiographic marker for early brain injury after aneurysmal subarachnoid hemorrhage (aSAH). We evaluated the role of the SEBES in performing decompressive craniectomy (DC) for poor-grade aSAH.

METHODS

We retrospectively analyzed all cases of poor-grade (World Federation of Neurosurgical Societies [WFNS] grade IV and V) aSAH in adults who underwent microsurgery at our center between April 2017 and March 2021. Patient demographics, clinical presentation, imaging findings, and surgical data were obtained. The study endpoints of DC rate, complications, and functional outcomes (modified Rankin Scale score >3) were compared between the traditional surgery and SEBES-informed groups. A survival analysis was performed to estimate 180-day survival and hazard ratios for death.

RESULTS

The study included 116 patients (mean age, 60.8 ± 9.5 years, DCs [n = 63, 54.3%]). In the univariate analysis, age, intracranial pressure, midline shift, pupil changes, SEBES grade III-IV, traditional group, and WFNS grade Ⅴ were associated with DC. DC (46.4% vs. 67.4%) and in-hospital mortality rates (9.6% vs. 25.6%) were significantly lower in the SEBES-informed group. At day 180 after admission, modified Rankin Scale scores did not significantly differ between the 2 groups, but 180-day survival was significantly higher in the SEBES-informed group (78.1% vs. 53.5%). In the multivariable analysis, age, pupil changes, being in the traditional group, and delayed cerebral ischemia were independently associated with 180-day postadmission mortality.

CONCLUSIONS

The SEBES provides good imaging support for preoperative and intraoperative intracranial pressure management in poor-grade aSAH, allowing for improved DC-related decision-making and better 180-day survival.

Twitter Journal Club Impact on Engagement Metrics of the Neurocritical Care Journal

BACKGROUND

Twitter journal clubs are a modern way of highlighting articles published in a scientific journal. The Neurocritical Care journal (NCC) initiated a bimonthly, Twitter-based, online journal club in 2015 to increase the outreach of its published articles. We hypothesize that articles included in the Neurocritical Care Society Twitter Journal Club (NCSTJC) had greater engagement than other articles published during the same time period. We also investigated the relationship between number of citations and Altmetric score to assess whether the enhanced online activity resulted in higher citations.

METHODS

We gathered data in August 2020 on engagement metrics (number of downloads, Altmetric score, relative citation ratio, and number of citations) of all articles published in NCC between 2015 and 2018. Articles were analyzed into two groups: one featured in NCSTJC and the rest that were not (non-NCSTJC1), and the other comprised those that were not in NCSTJC but published under a similar category of articles as NCSTJC (non-NCSTJC2). Results were analyzed using descriptive statistics, and summary measures were used to report the spread. The groups were compared by using the Wilcoxon rank sum test, given that the data were not normally distributed. Spearman's rank correlation was used to assess correlation between Altmetric score and citations for the articles in the NCSTJC and non-NCSTJC groups. For comparison, the top ten cited articles in NCC were analyzed for similar correlations.

RESULTS

Between 2015 and 2018, NCC published 529 articles, 24 of which were included in the Twitter journal club. A total of 406 articles were published in the same category as the category of articles selected for NCSTJC. The articles discussed as a part of NCSTJC had a statistically significant trend toward a higher number of downloads, Altmetric score, relative citation ratio, and number of citations than rest of the articles published in the journal during the same time period and the rest of the articles published in same categories. Three NCSTJC articles were among the ten most-cited articles published by NCC between 2015 and 2018. We did not find a correlation between Altmetric scores and number of citations in the NCSTJC or non-NCSTJC1 or non-NCSTJC2 group, but there was a strong correlation between these two variables in high performing articles when the top ten cited articles were analyzed.

CONCLUSIONS

Scientific journals are evolving their social media strategies in attempt to increase the outreach of their articles to the medical community. Platforms such as Twitter journal clubs can enhance such engagement. The long-term influence of such strategies on the impact factor of a medical journal and traditional engagement metrics, such as citations, calls for further research.

Applying Quantitative Radiographic Image Markers to Predict Clinical Complications After Aneurysmal Subarachnoid Hemorrhage: A Pilot Study

Accurately predicting clinical outcome of aneurysmal subarachnoid hemorrhage (aSAH) patients is difficult. The purpose of this study was to develop and test a new fully-automated computer-aided detection (CAD) scheme of brain computed tomography (CT) images to predict prognosis of aSAH patients. A retrospective dataset of 59 aSAH patients was assembled. Each patient had 2 sets of CT images acquired at admission and prior-to-discharge. CAD scheme was applied to segment intracranial brain regions into four subregions, namely, cerebrospinal fluid (CSF), white matter (WM), gray matter (GM), and leaked extraparenchymal blood (EPB), respectively. CAD then detects sulci and computes 9 image features related to 5 volumes of the segmented sulci, EPB, CSF, WM, and GM and 4 volumetrical ratios to sulci. Subsequently, applying a leave-one-case-out cross-validation method embedded with a principal component analysis (PCA) algorithm to generate optimal feature vector, 16 support vector machine (SVM) models were built using CT images acquired either at admission or prior-to-discharge to predict each of eight clinically relevant parameters commonly used to assess patients' prognosis. Finally, a receiver operating characteristics (ROC) method was used to evaluate SVM model performance. Areas under ROC curves of 16 SVM models range from 0.62 ± 0.07 to 0.86 ± 0.07. In general, SVM models trained using CT images acquired at admission yielded higher accuracy to predict short-term clinical outcomes, while SVM models trained using CT images acquired prior-to-discharge demonstrated higher accuracy in predicting long-term clinical outcomes. This study demonstrates feasibility to predict prognosis of aSAH patients using new quantitative image markers generated by SVM models.

Age dependency and modification of the Subarachnoid Hemorrhage Early Brain Edema Score

OBJECTIVE

The Subarachnoid Hemorrhage Early Brain Edema Score (SEBES) system measures cerebral edema on CT and can be used to predict outcome after subarachnoid hemorrhage (SAH). The authors developed a modified SEBES (SEBES 6c) and assessed whether it could predict outcome after SAH better than the SEBES. Furthermore, they verified the age dependency of these scores.

METHODS

In this retrospective study, all patients with aneurysmal SAH in the period from January 2011 to February 2017 at a single institution were analyzed. The SEBES, which is based on the absence of visible sulci at two defined CT levels (0-4 points), and the SEBES 6c were determined from the initial CT. The SEBES 6c system includes the two levels from the original SEBES and one level located 2 cm below the vertex (0-6 points). The authors investigated whether the various SEBESs are age dependent and if they can predict delayed infarction (DI) and outcome.

RESULTS

Two hundred sixty-one patients met the study inclusion criteria. The SEBES was an independent predictor for DI (OR 1.6 per 1-point increase) and unfavorable outcome (OR 1.36 per 1-point increase), in accordance with findings in the first publication on SEBES. However, here the authors found that the SEBES was age dependent. In the age group younger than 60 years, the patients with high-grade SEBESs (3-4 points) had DIs and unfavorable outcomes significantly more often than the patients with low-grade scores (0-2 points). In the age groups 60-69 years and ≥ 70 years, no significant differences in DI and outcome were identified between high-grade and low-grade scores, although trends toward DI and unfavorable outcomes among the 60-69 age group were noted in patients with high-grade SEBESs.Receiver operating characteristic curve analysis showed that SEBES 6c had a higher prognostic value in predicting outcome than SEBES (p < 0.001). Furthermore, SEBES 6c predicted an unfavorable outcome (OR 1.31 per 1-point increase) and DI (OR 1.36 per 1-point increase) independent of vasospasms. SEBES 6c showed an age dependency similar to that of SEBES.

CONCLUSIONS

SEBES 6c is more suitable for predicting outcome after SAH than SEBES. Furthermore, it predicts outcome and DI independently of vasospasm, so it can be used to differentiate between early brain injury- and vasospasm-dependent infarctions and outcome. However, SEBES and SEBES 6c are both age dependent and can be used for patients aged < 60 years and may have limited suitability for patients aged 60-69 years and no suitability for patients aged ≥ 70 years.

The physiopathology of spontaneous hemorrhagic stroke: a systematic review

Hemorrhagic stroke (HS) is a major cause of death and disability worldwide, despite being less common, it presents more aggressively and leads to more severe sequelae than ischemic stroke. There are two types of HS: Intracerebral Hemorrhage (ICH) and Subarachnoid Hemorrhage (SAH), differing not only in the site of bleeding, but also in the mechanisms responsible for acute and subacute symptoms. This is a systematic review of databases in search of works of the last five years relating to the comprehension of both kinds of HS. Sixty two articles composed the direct findings of the recent literature and were further characterized to construct the pathophysiology in the order of events. The road to the understanding of the spontaneous HS pathophysiology is far from complete. Our findings show specific and individual results relating to the natural history of the disease of ICH and SAH, presenting common and different risk factors, distinct and similar clinical manifestations at onset or later days to weeks, and possible complications for both.

Automated Quantification of Reduced Sulcal Volume Identifies Early Brain Injury After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Early brain injury may be a more significant contributor to poor outcome after aneurysmal subarachnoid hemorrhage (aSAH) than vasospasm and delayed cerebral ischemia. However, studying this process has been hampered by lack of a means of quantifying the spectrum of injury. Global cerebral edema (GCE) is the most widely accepted manifestation of early brain injury but is currently assessed only through subjective, qualitative or semi-quantitative means. Selective sulcal volume (SSV), the CSF volume above the lateral ventricles, has been proposed as a quantitative biomarker of GCE, but is time-consuming to measure manually. Here we implement an automated algorithm to extract SSV and evaluate the age-dependent relationship of reduced SSV on early outcomes after aSAH.

METHODS

We selected all adults with aSAH admitted to a single institution with imaging within 72 hours of ictus. Scans were assessed for qualitative presence of GCE. SSV was automatically segmented from serial CTs using a deep learning-based approach. Early SSV was the lowest SSV from all early scans. Modified Rankin Scale score of 4 to 6 at hospital discharge was classified as a poor outcome.

RESULTS

Two hundred forty-four patients with aSAH were included. Sixty-five (27%) had GCE on admission while 24 developed it subsequently within 72 hours. Median SSV on admission was 10.7 mL but frequently decreased, with minimum early SSV being 3.0 mL (interquartile range, 0.3-11.9). Early SSV below 5 mL was highly predictive of qualitative GCE (area under receiver-operating-characteristic curve, 0.90). Reduced early SSV was an independent predictor of poor outcome, with a stronger effect in younger patients.

CONCLUSIONS

Automated assessment of SSV provides an objective biomarker of GCE that can be leveraged to quantify early brain injury and dissect its impact on outcomes after aSAH. Such quantitative analysis suggests that GCE may be more impactful to younger patients with SAH.

Machine Learning to Predict Delayed Cerebral Ischemia and Outcomes in Subarachnoid Hemorrhage

OBJECTIVE

To determine whether machine learning (ML) algorithms can improve the prediction of delayed cerebral ischemia (DCI) and functional outcomes after subarachnoid hemorrhage (SAH).

METHODS

ML models and standard models (SMs) were trained to predict DCI and functional outcomes with data collected within 3 days of admission. Functional outcomes at discharge and at 3 months were quantified using the modified Rankin Scale (mRS) for neurologic disability (dichotomized as good [mRS ≤ 3] vs poor [mRS ≥ 4] outcomes). Concurrently, clinicians prospectively prognosticated 3-month outcomes of patients. The performance of ML, SMs, and clinicians were retrospectively compared.

RESULTS

DCI status, discharge, and 3-month outcomes were available for 399, 393, and 240 participants, respectively. Prospective clinician (an attending, a fellow, and a nurse) prognostication of 3-month outcomes was available for 90 participants. ML models yielded predictions with the following area under the receiver operating characteristic curve (AUC) scores: 0.75 ± 0.07 (95% confidence interval [CI] 0.64-0.84) for DCI, 0.85 ± 0.05 (95% CI 0.75-0.92) for discharge outcome, and 0.89 ± 0.03 (95% CI 0.81-0.94) for 3-month outcome. ML outperformed SMs, improving AUC by 0.20 (95% CI -0.02 to 0.4) for DCI, by 0.07 ± 0.03 (95% CI -0.0018 to 0.14) for discharge outcomes, and by 0.14 (95% CI 0.03-0.24) for 3-month outcomes and matched physician's performance in predicting 3-month outcomes.

CONCLUSION

ML models significantly outperform SMs in predicting DCI and functional outcomes and has the potential to improve SAH management.

Edema Resolution and Clinical Assessment in Poor-Grade Subarachnoid Hemorrhage: Useful Indicators to Predict Delayed Cerebral Infarctions?

Background: The level of consciousness and cerebral edema are among the indicators that best define the intensity of early brain injury following aneurysmal subarachnoid hemorrhage (aSAH). Although these indicators are usually altered in patients with a poor neurological status, their usefulness for selecting patients at risk of cerebral infarction (CI) is not well established. Furthermore, little is known about the evolution of these indicators during the first week of post-ictal events. Our study focused on describing the association of the longitudinal course of these predictors with CI occurrence in patients with severe aSAH. Methods: Out of 265 aSAH patients admitted consecutively to the same institution, 80 patients with initial poor neurological status (WFNS 4–5) were retrospectively identified. After excluding 25 patients with early mortality, a total of 47 patients who underwent early CT (<3 days) and late CT (<7 days) acquisitions were included in the study. Early cerebral edema and delayed cerebral edema were calculated using the SEBES score, and the level of consciousness was recorded daily during the first week using the Glasgow Coma Scale (GCS). Results: There was a significant improvement in the SEBES (Early-SEBES median (IQR) = 3 (2–4) versus Delayed-SEBES = 2 (1–3); p = 0.001) and in GCS scores (B = 0.32; 95% CI 0.15–0.49; p = 0.001) during the first week. When comparing the ROC curves of Delayed-SEBES vs Early-SEBES as predictors of CI, no significant differences were found (Early-SEBES Area Under the Curve: 0.65; Delayed-SEBES: 0.62; p = 0.17). Additionally, no differences were observed in the relationship between the improvement in the GCS across the first week and the occurrence of CI (p = 0.536). Conclusions: Edema and consciousness level improvement did not seem to be associated with the occurrence of CI in a surviving cohort of patients with severe aSAH. Our results suggest that intensive monitoring should not be reduced in patients with a poor neurological status regardless of an improvement in cerebral edema and level of consciousness during the first week after bleeding.

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.

Significance and Diagnostic Accuracy of Early S100B Serum Concentration after Aneurysmal Subarachnoid Hemorrhage

Background: Early brain injuries (EBI) are one of the most important causes of morbidity and mortality after subarachnoid hemorrhage. At admission, a third of patients are unconscious (spontaneously or sedated) and EBI consequences are not evaluable. To date, it is unclear who will still be comatose (with severe EBI) and who will recover (with less severe EBI) once the aneurysm is treated and sedation withdrawn. The objective of the present study was to determine the diagnostic accuracy of S100B levels at hospital admission to identify patients with severe neurological consequences of EBI. Methods: Patients were consecutively included in this prospective blinded observational study. A motor component of the Glasgow coma score under 6 on day 3 was used to define patients with severe neurological consequences of EBI. Results: A total of 81 patients were included: 25 patients were unconscious at admission, 68 were treated by coiling. On day 3, 12 patients had severe consequences of EBI. A maximal S100B value between admission and day 1 had an area under the receiver operating characteristic curve (AUC) of 86.7% to predict severe EBI consequences. In patients with impaired consciousness at admission, the AUC was 88.2%. Conclusion: Early S100B seems to have a good diagnostic value to predict severe EBI. Before claiming the usefulness of S100B as a surrogate marker of EBI severity to start earlier multimodal monitoring, these results must be confirmed in an independent validation cohort.

CT-Based Classification of Acute Cerebral Edema: Association with Intracranial Pressure and Outcome

BACKGROUND AND PURPOSE

Brain edema after acute cerebral lesions may lead to raised intracranial pressure (ICP) and worsen outcome. Notwithstanding, no CT-based scoring system to quantify edema formation exists. This retrospective correlative analysis aimed to establish a valid and definite CT score quantifying brain edema after common acute cerebral lesions.

METHODS

A total of 169 CT investigations in 60 patients were analyzed: traumatic brain injury (TBI; n = 47), subarachnoid hemorrhage (SAH; n = 70), intracerebral hemorrhage (ICH; n = 42), and ischemic stroke (n = 10). Edema formation was classified as 0: no edema, 1: focal edema confined to 1 lobe, 2: unilateral edema > 1 lobe, 3: bilateral edema, 4: global edema with disappearance of sulcal relief, and 5: global edema with basal cisterns effacement. ICP and Glasgow Outcome Score (GOS) were correlated to edema formation.

RESULTS

Median ICP values were 12.0, 14.0, 14.9, 18.2, and 25.9 mm Hg in grades 1-5, respectively. Edema grading significantly correlated with ICP (r = .51; P < .0001) in focal and global cerebral edema, particularly in patients with TBI, SAH, and ICH (r = .5, P < .001; r = .5; P < .0001; r = .6, P < .0001, respectively). At discharge, 23.7% of patients achieved a GOS of 5 or 4, 65.0% reached a GOS of 3 or 2, and 11.9% died (GOS 1). CT-score of cerebral edema in all patients correlated with outcome (r = -.3, P = .046).

CONCLUSION

The proposed CT-based grading of extent of cerebral edema significantly correlated with ICP and outcome in TBI, SAH, and ICH patients and might be helpful for standardized description of CT-images and as parameter for clinical studies, for example, measuring effects of antiedematous therapies.

Automated quantitative assessment of cerebral edema after ischemic stroke using CSF volumetrics

Reduction in CSF volume from baseline to follow-up CT at or beyond 24 -hs can serve as a quantitative biomarker of cerebral edema after stroke. We have demonstrated that assessment of CSF displacement reflects edema metrics such as lesion volume, midline shift, and neurologic deterioration. We have also developed a neural network-based image segmentation algorithm that can automatically measure CSF volume on serial CT scans from stroke patients. We have integrated this algorithm into an image processing pipeline that can extract this edema biomarker from large cohorts of stroke patients. Finally, we have created a stroke repository that can archive and process images from thousands of stroke patients in order to measure CSF volumetrics. We plan on applying this metric as a quantitative endophenotype of cerebral edema to facilitate early prediction of clinical deterioration as well as large-scale genetic studies.

Delayed Resolution of Cerebral Edema Is Associated With Poor Outcome After Nontraumatic Subarachnoid Hemorrhage

Background and Purpose- Global cerebral edema occurs in up to 57% of patients with subarachnoid hemorrhage (SAH) and is associated with prolonged hospital stay and poor outcome. Recently, admission brain edema was successfully graded using a simplified computed tomography-based semiquantitative score (subarachnoid hemorrhage early brain edema score [SEBES]). Longitudinal evaluation of the SEBES grade may discriminate patients with rapid and delayed edema resolution after SAH. Here, we aimed to describe the resolution of brain edema and to study the relationship between this radiographic biomarker and hospital course and outcome after SAH. Methods- For the current observational cohort study, computed tomography scans of 283 consecutive nontraumatic SAH patients admitted to the neurological intensive care unit of a tertiary hospital were graded based on the absence of visible sulci at 2 predefined brain tissue levels in each hemisphere (SEBES ranging from 0 to 4). A score of ≥3 was defined as high-grade SEBES. Multivariable regression models using generalized linear models were used to identify associated factors with delayed edema resolution based on the median time to resolution (SEBES ≤2) in SAH survivors. Results- Patients were 57 years old (interquartile range, 48-68) and presented with a median admission Hunt and Hess grade of 3 (interquartile range, 1-5). High-grade SEBES was common (106/283, 37%) and resolved within a median of 8 days (interquartile range, 4-15) in survivors (N=80). Factors associated with delayed edema resolution were early (<72 hours) hypernatremia (>150 mmol/L; adjusted odds ratio [adjOR], 4.88; 95% CI, 1.68-14.18), leukocytosis (>15 G/L; adjOR, 3.14; 95% CI, 1.24-8.77), hyperchloremia (>121 mmol/L; adjOR, 5.24; 95% CI, 1.64-16.76), and female sex (adjOR, 3.71; 95% CI, 1.01-13.64) after adjusting for admission Hunt and Hess grade and age. Delayed brain edema resolution was an independent predictor of worse functional 3-month outcome (adjOR, 2.52; 95% CI, 1.07-5.92). Conclusions- Our data suggest that repeated quantification of the SEBES can identify SAH patients with delayed edema resolution. Based on its' prognostic value as radiographic biomarker, the SEBES may be integrated in future trials aiming to improve edema resolution after SAH.

Reduction in Cerebrospinal Fluid Volume as an Early Quantitative Biomarker of Cerebral Edema After Ischemic Stroke

Background and Purpose- Cerebral edema (CED) develops in the hours to days after stroke; the resulting increase in brain volume may lead to midline shift (MLS) and neurological deterioration. The time course and implications of edema formation are not well characterized across the spectrum of stroke. We analyzed displacement of cerebrospinal fluid (ΔCSF) as a dynamic quantitative imaging biomarker of edema formation. Methods- We selected subjects enrolled in a stroke cohort study who presented within 6 hours of onset and had baseline and ≥1 follow-up brain computed tomography scans available. We applied a neural network-based algorithm to quantify hemispheric CSF volume at each imaging time point and modeled CSF trajectory over time (using a piecewise linear mixed-effects model). We evaluated ΔCSF within the first 24 hours as an early biomarker of CED (defined as developing MLS on computed tomography beyond 24 hours) and poor outcome (modified Rankin Scale score, 3-6). Results- We had serial imaging in 738 subjects with stroke, of whom 91 (13%) developed CED with MLS. Age did not differ (69 versus 70 years), but baseline National Institutes of Health Stroke Scale was higher (16 versus 7) and baseline CSF volume lower (132 versus 161 mL, both P<0.001) in those with CED. ΔCSF was faster in those developing MLS, with the majority seen by 24 hours (36% versus 11% or 2.4 versus 0.8 mL/h; P<0.0001). Risk of CED almost doubled for every 10% ΔCSF within 24 hours (odds ratio, 1.76 [95% CI, 1.46-2.14]), adjusting for age, glucose, and National Institutes of Health Stroke Scale. Risk of neurological deterioration (1.6-point increase in National Institutes of Health Stroke Scale at 24 hours) and poor outcome (adjusted odds ratio, 1.34 [95% CI, 1.15-1.56]) was also greater for every 10% increase in ΔCSF. Conclusions- CSF volumetrics provides quantitative evaluation of early edema formation. ΔCSF from baseline to 24-hour computed tomography is a promising early biomarker for the development of MLS and worse neurological outcome.

Inflammation in delayed ischemia and functional outcomes after subarachnoid hemorrhage

BACKGROUND

Inflammatory mechanism has been implicated in delayed cerebral ischemia (DCI) and poor functional outcomes after subarachnoid hemorrhage (SAH). Identification of cytokine patterns associated with inflammation in acute SAH will provide insights into underlying biological processes of DCI and poor outcomes that may be amenable to interventions.

METHODS

Serum samples were collected from a prospective cohort of 60 patients with acute non-traumatic SAH at four time periods (< 24 h, 24-48 h, 3-5 days, and 6-8 days after SAH) and concentration levels of 41 cytokines were measured by multiplex immunoassay. Logistic regression analysis was used to identify cytokines associated with DCI and poor functional outcomes. Correlation networks were constructed to identify cytokine clusters.

RESULTS

Of the 60 patients enrolled in the study, 14 (23.3%) developed DCI and 16 (26.7%) had poor functional outcomes at 3 months. DCI was associated with increased levels of PDGF-ABBB and CCL5 and decreased levels of IP-10 and MIP-1α. Poor functional outcome was associated with increased levels of IL-6 and MCP-1α. Network analysis identified distinct cytokine clusters associated with DCI and functional outcomes.

CONCLUSIONS

Serum cytokine patterns in early SAH are associated with poor functional outcomes and DCI. The significant cytokines primarily modulate the inflammatory response. This supports earlier SAH studies linking inflammation and poor outcomes. In particular, this study identifies novel cytokine patterns over time that may indicate impending DCI.

The Subarachnoid Hemorrhage Early Brain Edema Score Predicts Delayed Cerebral Ischemia and Clinical Outcomes

BACKGROUND

Early brain injury (EBI) after subarachnoid hemorrhage (SAH) is an important determinant of clinical outcomes. However, a major hindrance to studies of EBI is the lack of radiographic surrogate marker.

OBJECTIVE

To propose a scoring system based on early changes in clinically obtained computed tomography (CT), called the Subarachnoid hemorrhage Early Brain Edema Score (SEBES).

METHODS

Patients with spontaneous aneurysmal SAH and a CT within 24 h of ictus were included. We defined SEBES as a scale of 0 to 4 points according to the (1) absence of visible sulci caused by effacement of sulci or (2) absence of visible sulci with disruption of the gray-white matter junction at 2 predetermined levels in each hemisphere. Prognostic value of the SEBES grade for the prediction of delayed cerebral ischemia (DCI) and unfavorable outcomes was assessed. A separate cohort of patients was used as a validation cohort.

RESULTS

Of the 164 subjects in our study, high-grade SEBES (3 or 4 points) was identified in 48 patients (29.3%). CT interobserver reliability of SEBES grades was high with a Kappa value of 0.89. After adjusting for covariables, SEBES was identified as an independent predictor of DCI (OR = 2.24, 95% CI: 1.58-3.17) and unfavorable outcome (OR = 3.45, 95% CI: 1.95-6.07). In our validation cohort, 84 subjects showed similar predictive power of SEBES for a prediction of DCI and unfavorable long-term outcome.

CONCLUSION

SEBES may be a surrogate marker of EBI and predicts DCI and clinical outcomes after SAH.

Early Brain Injury After Poor-Grade Subarachnoid Hemorrhage

PURPOSE OF REVIEW

Over the last years, the focus of clinical and animal research in subarachnoid hemorrhage (SAH) shifted towards the early phase after the bleeding based on the association of the early injury pattern (first 72 h) with secondary complications and poor outcome. This phase is commonly referenced as early brain injury (EBI). In this clinical review, we intended to overview commonly used definitions of EBI, underlying mechanisms, and potential treatment implications.

RECENT FINDINGS

We found a large heterogeneity in the definition used for EBI comprising clinical symptoms, neuroimaging parameters, and advanced neuromonitoring techniques. Although specific treatments are currently not available, therapeutic interventions are aimed at ameliorating EBI by improving the energy/supply mismatch in the early phase after SAH. Future research integrating brain-derived biomarkers is warranted to improve our pathophysiologic understanding of EBI in order to ameliorate early injury patterns and improve patients' outcomes.

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.

Mechanisms of Global Cerebral Edema Formation in Aneurysmal Subarachnoid Hemorrhage

A growing body of clinical literature emphasizes the impact of cerebral edema in early brain injury following aneurysmal subarachnoid hemorrhage (aSAH). Aneurysm rupture itself initiates global cerebral edema in up to two thirds of cases. Although cerebral edema is not a universal feature of aSAH, it portends a poor clinical course, with quantitative analysis revealing a direct correlation between cerebral edema and poor outcome, including mortality and cognitive deficits. Mechanistically, global cerebral edema has been linked to global ischemia at the time of aneurysm rupture, dysfunction of autoregulation, blood breakdown products, neuroinflammation, and hyponatremia/endocrine abnormalities. At a molecular level, several culprits have been identified, including aquaporin-4, matrix metalloproteinase-9, SUR1-TRPM4 cation channels, vascular endothelial growth factor, bradykinin, and others. Here, we review these cellular and molecular mechanisms of global cerebral edema formation in aSAH. Given the importance of edema to the outcome of patients with aSAH and its status as a highly modifiable pathological process, a better understanding of cerebral edema in aSAH promises to hasten the development of medical therapies to improve outcomes in this frequently devastating disease.

Emerging Markers of Early Brain Injury and Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage is characterized by a highly complex pathophysiology and results in neurologic deterioration after the inciting bleed. Despite its significant consequences, prompt diagnosis can be elusive and treatment is often administered too late. Early brain injury, which occurs within the first 72 hours after ictus, may be an important factor for delayed cerebral ischemia and poor overall outcome. Here, we explore the purported clinical and pathologic manifestations of early brain injury to identify biomarkers that could have prognostic value.

METHODS

We review the literature and discuss potential emerging markers of delayed cerebral ischemia in the context of early brain injury.

RESULTS

The following clinical features and biomarkers were examined: global cerebral edema, ictal loss of consciousness, ultra early angiographic vasospasm, continuous electroencephalogram monitoring, systemic inflammatory response syndrome, cellular mediators of the inflammatory response, and hematologic derangements.

CONCLUSIONS

Some of these markers possess independent value for determining the risk of complications after aneurysmal subarachnoid hemorrhage. However, their use is limited because of a variety of factors, but they do provide an avenue of further study to aid in diagnosis and management.

Systematic model of peripheral inflammation after subarachnoid hemorrhage

OBJECTIVE

To investigate inflammatory processes after aneurysmal subarachnoid hemorrhage (aSAH) with network models.

METHODS

This is a retrospective observational study of serum samples from 45 participants with aSAH analyzed at multiple predetermined time points: <24 hours, 24 to 48 hours, 3 to 5 days, and 6 to 8 days after aSAH. Concentrations of cytokines were measured with a 41-plex human immunoassay kit, and the Pearson correlation coefficients between all possible cytokine pairs were computed. Systematic network models were constructed on the basis of correlations between cytokine pairs for all participants and across injury severity. Trends of individual cytokines and correlations between them were examined simultaneously.

RESULTS

Network models revealed that systematic inflammatory activity peaks at 24 to 48 hours after the bleed. Individual cytokine levels changed significantly over time, exhibiting increasing, decreasing, and peaking trends. Platelet-derived growth factor (PDGF)-AA, PDGF-AB/BB, soluble CD40 ligand, and tumor necrosis factor-α (TNF-α) increased over time. Colony-stimulating factor (CSF) 3, interleukin (IL)-13, and FMS-like tyrosine kinase 3 ligand decreased over time. IL-6, IL-5, and IL-15 peaked and decreased. Some cytokines with insignificant trends show high correlations with other cytokines and vice versa. Many correlated cytokine clusters, including a platelet-derived factor cluster and an endothelial growth factor cluster, were observed at all times. Participants with higher clinical severity at admission had elevated levels of several proinflammatory and anti-inflammatory cytokines, including IL-6, CCL2, CCL11, CSF3, IL-8, IL-10, CX3CL1, and TNF-α, compared to those with lower clinical severity.

CONCLUSIONS

Combining reductionist and systematic techniques may lead to a better understanding of the underlying complexities of the inflammatory reaction after aSAH.