From vasospasm to early brain injury: new frontiers in subarachnoid haemorrhage research

A nomogram for predicting the risk of cerebral vasospasm after neurosurgical clipping in patients with aneurysmal subarachnoid hemorrhage

Purpose

Cerebral vasospasm (CVS) is a common complication that occurs after neurosurgical clipping of intracranial aneurysms in patients with aSAH. This complication can lead to clinical deterioration and a poor prognosis. The aim of this study is to explore the risk factors for CVS in aSAH patients who have undergone neurosurgical clipping, develop a nomogram for CVS, and evaluate its performance.

Methods

Patients with aSAH who underwent neurosurgical clipping in the Department of Neurosurgery from January 2018 to January 2023 were selected as the subjects of this research. The clinical data of these patients were retrospectively analyzed. Logistic multivariate regression analysis was employed to identify the independent risk factors of CVS. A clinical prediction model in the form of a nomogram for CVS was developed using the R programming language and subsequently evaluated for its performance and quality.

Results

A total of 156 patients with aSAH were included in the analysis, comprising 109 patients in the training set and 47 patients in the validation set. In the training cohort, 27 patients (24.77%) developed CVS after neurosurgical clipping, while in the validation cohort, 15 patients (31.91%) experienced CVS. Multivariate regression analysis revealed that age, Hcy, WBC, glucose/potassium ratio, aneurysm location, and modified Fisher grade were independent risk factors for CVS. The nomogram exhibited excellent discriminative performance in both the training set (AUC = 0.885) and the validation set (AUC = 0.906).

Conclusion

CVS was a prevalent complication following neurosurgical clipping in patients with aSAH, with a highly intricate pathogenesis and pathophysiological course. Early prediction of CVS represented a significant challenge in clinical practice. In this study, age, Hcy, WBC, glucose/potassium ratio, aneurysm location, and modified Fisher grade emerged as independent risk factors for CVS. The resulting nomogram demonstrated substantial predictive value.

Risk factors for cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage

Introduction

Aneurysmal subarachnoid hemorrhage is a type of spontaneous hemorrhagic stroke, which is caused by a ruptured cerebral aneurysm. Cerebral vasospasm (CVS) is the most grievous complication of subarachnoid hemorrhage (SAH). The aim of this study was to examine the risk factors that influence the onset of CVS that develops after endovascular coil embolization of a ruptured aneurysm.

Materials and methods

The study was designed as a cross-sectional study. The patients included in the study were 18 or more years of age, admitted within a period of 24 h of symptom onset, diagnosed and treated at a university medical center in Serbia during a 5-year period.

Results

Our study showed that the maximum recorded international normalized ratio (INR) values in patients who were not receiving anticoagulant therapy and the maximum recorded white blood cells (WBCs) were strongly associated with cerebrovascular spasm, increasing its chances 4.4 and 8.4 times with an increase of each integer of the INR value and 1,000 WBCs, respectively.

Conclusions

SAH after the rupture of cerebral aneurysms creates an endocranial inflammatory state whose intensity is probably directly related to the occurrence of vasospasm and its adverse consequences.

Temporal evolution of cerebral computed tomography perfusion after acute subarachnoid hemorrhage: a prospective cohort study

Background

Changes in cerebral perfusion occur in subarachnoid hemorrhage that possibly relate to clinical presentation and complications.

Purpose

To evaluate changes in computed tomography perfusion (CTP) parameters between the acute and subacute stage of subarachnoid hemorrhage. To analyze correlation of these parameters to SAH severity and delayed cerebral ischemia.

Material and Methods

Cerebral CT perfusion was assessed in a prospective cohort of 44 patients with acute subarachnoid hemorrhage at < 72 h (CTP1) and 8–10 days (CTP2), using the mean of all regions of interest. Regions of interest were located at arterial territories of the anterior, middle, and posterior cerebral artery and basal ganglia and midpons cerebellar hemispheres. Linear regression models (univariable and multivariable) were used to explore the association between changes in perfusion parameters (absolute and relative differences) and relevant clinical data.

Results

Worse perfusion parameters on the first 72 h were correlated with poor admission clinical scores: cerebral blood flow positively correlated with Glasgow Coma Scale (rS = 0.398, P = 0.008), and negatively correlated with Hunt & Hess scale (rS = −0.348, P = 0.020) and World Federation of Neurosurgeons scale (rS = −0.384, P = 0.010). Cerebral blood volume positively correlated with Glasgow Coma Scale (rS = 0.332, P = 0.028) and negatively correlated with World Federation of Neurosurgeons scale (rS = −0.353, P = 0.019). Mean transit time negatively correlated with Glasgow Coma Scale (rS = −0.415, P = 0.005) and positively correlated with Hunt & Hess scale (rS = 0.471, P = 0.001) and World Federation of Neurosurgeons scale (rS = 0.386, P = 0.010) scores. There were no differences between absolute CTP1/CTP2 parameters. Patients with delayed cerebral ischemia had ΔTmax mean decrease of 2.08 s (95% CI = −4.04–−0.12; P = 0.038).

Conclusion

Early cerebral hypoperfusion correlates with poor clinical grade at admission in subarachnoid hemorrhage and with higher amounts of blood. Tmax was decreased at 8–10 days, in patients with delayed cerebral ischemia, which may favor the application value of Tmax in signaling delayed cerebral ischemia.

Recent Advances in Stem Cell Research in Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a type of hemorrhagic stroke with significant morbidity and mortality, and it often leads to poor clinical outcome. Although great efforts have been made toward animal and clinical studies, optimal therapy of SAH remains a challenge for scientists and clinicians. Increasing evidence suggests that stem-cell-based therapies may provide innovative approaches for treatment of SAH-related disability. In this review, we summarized the recent advances in stem cell research in SAH. Neuroregeneration after SAH could be conducted by the activation of endogenous neural stem cells (NSCs), transplantation of external stem cells, or reprogramming non-neuronal cell to neurons. The potential mechanism and signaling pathways, as well as the efficiency and safety of these stem cell treatments, were discussed in detail. Although lots of challenges remain for translating the laboratory findings and technologies into clinical therapies, these research studies provided the foundation and guidance for using different resources of stem cells as a brain repair strategy after SAH.

Sodium/Hydrogen Exchanger 1 Participates in Early Brain Injury after Subarachnoid Hemorrhage both in vivo and in vitro via Promoting Neuronal Apoptosis

Sodium/hydrogen exchanger 1 (NHE1) plays an essential role in maintaining intracellular pH (pHi) homeostasis in the central nervous system (CNS) under physiological conditions, and it is also associated with neuronal death and intracellular Na⁺ and Ca²⁺ overload induced by cerebral ischemia. However, its roles and underlying mechanisms in early brain injury (EBI) induced by subarachnoid hemorrhage (SAH) have not been fully explored. In this research, a SAH model in adult male rat was established through injecting autologous arterial blood into prechiasmatic cistern. Meanwhile, primary cultured cortical neurons of rat treated with 5 μM oxygen hemoglobin (OxyHb) for 24 h were applied to mimic SAH in vitro. We find that the protein levels of NHE1 are significantly increased in brain tissues of rats after SAH. Downregulation of NHE1 by HOE642 (a specific chemical inhibitor of NHE1) and genetic-knockdown can effectively alleviate behavioral and cognitive dysfunction, brain edema, blood-brain barrier (BBB) injury, inflammatory reactions, oxidative stress, neurondegeneration, and neuronal apoptosis, all of which are involved in EBI following SAH. However, upregulation of NHE1 by genetic-overexpression can produce opposite effects. Additionally, inhibiting NHE1 significantly attenuates OxyHb-induced neuronal apoptosis in vitro and reduces interaction of NHE1 and CHP1 both in vivo and in vitro. Collectively, we can conclude that NHE1 participates in EBI induced by SAH through mediating inflammation, oxidative stress, behavioral and cognitive dysfunction, BBB injury, brain edema, and promoting neuronal degeneration and apoptosis.

Ischemic Lesions in Acute and Subacute Perimesencephalic Subarachnoid Hemorrhage

OBJECTIVE

Perimesencephalic hemorrhage (PMH) is a subtype of nonaneurysmal subarachnoid hemorrhage (SAH). In patients with aneurysmal SAH, the occurrence of acute ischemic lesions is associated with severity and poor outcome. We investigated the frequency of ischemic lesions on DWI in patients with PMH and compared it with the frequency of ischemic lesions in patients with aneurysmal SAH.

SUBJECTS AND METHODS

From a prospective cohort of 80 patients with acute spontaneous SAH, we included 15 patients with PMH and 39 patients with aneurysmal SAH who were matched on the basis of their clinical condition (World Federation of Neurological Societies grade 1 or 2). MRI was performed less than 72 hours after SAH, 8-10 days after SAH, or at both points in time. The number and distribution of lesions previously seen on DWI that were also seen on a second MRI examination were assessed. Nonparametric tests were used to compare groups.

RESULTS

Early acute ischemic lesions (those identified < 72 hours after SAH) were found in 46.2% of patients with PMH and in 62.9% of patients with aneurysmal SAH. No significant differences in the number of acute ischemic lesions between groups were noted less than 72 hours after SAH (median, 0.5 lesion [interquartile range {IQR}, two lesions] in patients with PMH vs one lesion [IQR, three lesions] in patients with aneurysmal SAH [p = 0.48] or 8-10 days after SAH (median, 0.5 lesion [IQR, four lesions] in patients with PMH vs 1.5 lesions [IQR, three lesions] in patients with aneurysmal SAH [p = 0.26]). However, 58.3% of patients with aneurysmal SAH had new infarcts at 8-10 days, compared with 7.1% of patients with PMH. Patients with PMH had diffuse ischemic lesions, whereas patients with aneurysmal SAH in the anterior circulation had mainly supratentorial lesions.

CONCLUSION

Early ischemic lesions appeared on DWI both in patients with PMH and in patients with aneurysmal SAH. The number of lesions increased during the time window for vasospasm, mainly in patients with aneurysmal SAH. Further studies are required to better understand the pathophysiologic mechanisms behind early ischemia in patients with PMH and their impact on prognosis.

Macrophage-Inducible C-Type Lectin/Spleen Tyrosine Kinase Signaling Pathway Contributes to Neuroinflammation After Subarachnoid Hemorrhage in Rats

BACKGROUND AND PURPOSE

Macrophage-inducible C-type lectin (Mincle, CLEC4E) receptor is reported involved in neuroinflammation in cerebral ischemia and traumatic brain injury. This study was designed to investigate the role of Mincle and its downstream spleen tyrosine kinase (Syk) signal pathway in early brain injury after subarachnoid hemorrhage (SAH) in a rat model.

METHODS

Two hundred fifteen male Sprague-Dawley rats (280-320 g) were subjected to endovascular perforation model of SAH. SAH grade, neurological score, and brain water content were measured at 24 hours after SAH. Mincle/Syk, as well as CARD9 (a member of the caspase-associated recruitment domain [CARD], involved in innate immune response), interleukin-1β,and myeloperoxidase expressions were analyzed by Western blot at 24 hours after SAH. Specific cell types that expressed Mincle were detected with double immunofluorescence staining. Mincle small interfering RNA, recombinant SAP130, and a selective Syk phosphorylation inhibitor piceatannol were used for intervention.

RESULTS

Brain water content increased and neurological functions decreased in rats after SAH. The expression of SAP130, Mincle, Syk, and p-Syk increased at 12 hours and peaked at 24 hours after SAH. Mincle small interfering RNA reduced interleukin-1β and infiltration of myeloperoxidase positive cells, decreased brain water content, and improved neurological functions at 24 hours after SAH. Recombinant SAP130 upregulated the expression of p-Syk and CARD9 and increased the levels of interleukin-1β and myeloperoxidase, even though it did not increase brain water content nor it deteriorated neurological function at 24 hours after SAH. Syk inhibitor piceatannol reduced brain edema at 24 hours after SAH.

CONCLUSION

Mincle/Syk is involved in early brain injury after SAH, and they may serve as new targets for therapeutic intervention.

External lumbar cerebrospinal fluid drainage in patients with aneurysmal subarachnoid hemorrhage: A systematic review and meta-analysis of controlled trials

INTRODUCTION

External lumbar drainage is a promising measure for the prevention of delayed aneurysmal subarachnoid hemorrhage-related ischemic complications.

METHODS

Controlled studies evaluating the effects of external lumbar drainage in patients with aneurysmal subarachnoid hemorrhage were included. Primary outcomes were: new cerebral infarctions and severe disability. Secondary outcomes were: clinical deterioration due to delayed cerebral ischemia, mortality, and the need of definitive ventricular shunting. Results were presented as pooled relative risks, with their 95% confidence intervals (95% CI).

RESULTS

A total of 6 controlled studies were included. Pooled relative risks were: new cerebral infarctions, 0.48 (95% CI: 0.32-0.72); severe disability, 0.5 (95% CI: 0.29-0.85); delayed cerebral ischemia-related clinical deterioration, 0.46 (95% CI: 0.34-0.63); mortality, 0.71 (95% CI: 0.24-2.06), and need of definitive ventricular shunting, 0.80 (95% CI: 0.51-1.24). Assessment of heterogeneity only revealed statistically significant indexes for the analysis of severe disability (I(2)=70% and P=.01).

CONCLUSION

External lumbar drainage was associated with a statistically significant decrease in the risk of delayed cerebral ischemia-related complications (cerebral infarctions and clinical deterioration), as well as the risk of severe disability; however, it was not translated in a lower mortality. Nevertheless, it is not prudent to provide definitive recommendations at this time because of the qualitative and quantitative heterogeneity among included studies. More randomized controlled trials with more homogeneous outcomes and definitions are needed to clarify its impact in patients with aneurysmal subarachnoid hemorrhage.