The effectiveness of lumbar cerebrospinal fluid drainage in aneurysmal subarachnoid hemorrhage with different bleeding amounts

Spatiotemporal dynamic changes of meningeal microenvironment influence meningeal lymphatic function following subarachnoid hemorrhage: from inflammatory response to tissue remodeling

BACKGROUND

Meningeal lymphatic vessels (mLVs) play a critical role in clearing erythrocytes from the subarachnoid space and immune cells from the brain parenchyma following subarachnoid hemorrhage (SAH). However, the drainage function of mLVs is impaired during the acute stage after SAH and gradually recovers in the subacute phase. We aimed to investigate the meningeal transcriptional response post-SAH and elucidate the dynamic influence of meningeal microenvironment on meningeal lymphatic function.

METHODS

We employed bioinformatics analysis of single-cell RNA sequencing and spatial transcriptomics to characterize the spatiotemporal dynamic changes in the early meningeal microenvironment post-SAH. In a mouse model of SAH, the early dynamic changes of the meningeal immune cells and the potential growth factor that promoted the early repair of the mLVs were further investigated and validated.

RESULTS

During the acute phase, myeloid cells early infiltrated the meninges and triggered inflammatory responses. In the subacute phase, the fibroblast population expanded significantly, contributing to tissue remodeling. The interplay between immune cells and fibroblasts regulated cell migration and phenotypic transition, potentially affecting the function of mLVs. Notably, placental growth factor (PGF) emerged as the most prominent ligand within the VEGF signaling pathway received by meningeal lymphatic endothelial cells (mLECs) post-SAH. This signaling event was associated with the early recovery of mLVs after acute immune responses.

CONCLUSIONS

Our study revealed a spatiotemporal transformation of the meningeal microenvironment from an "inflammatory response" phase to a "tissue remodeling" phase following SAH. Monocyte-derived macrophages and self-recruiting neutrophils contributed to impairment of mLVs in the acute stage, while PGF might serve as a key factor promoting early meningeal lymphatic function repair following the inflammatory response. These findings provided novel insights into the cellular dynamics underlying mLVs dysfunction and recovery post-SAH.

Natural flavonoids from herbs and nutraceuticals as ferroptosis inhibitors in central nervous system diseases: current preclinical evidence and future perspectives

Flavonoids are a class of important polyphenolic compounds, renowned for their antioxidant properties. However, recent studies have uncovered an additional function of these natural flavonoids: their ability to inhibit ferroptosis. Ferroptosis is a key mechanism driving cell death in central nervous system (CNS) diseases, including both acute injuries and chronic neurodegenerative disorders, characterized by iron overload-induced lipid peroxidation and dysfunction of the antioxidant defense system. This review discusses the therapeutic potential of natural flavonoids from herbs and nutraceuticals as ferroptosis inhibitors in CNS diseases, focusing on their molecular mechanisms, summarizing findings from preclinical animal models, and providing insights for clinical translation. We specifically highlight natural flavonoids such as Baicalin, Baicalein, Chrysin, Vitexin, Galangin, Quercetin, Isoquercetin, Eriodictyol, Proanthocyanidin, (-)-epigallocatechin-3-gallate, Dihydromyricetin, Soybean Isoflavones, Calycosin, Icariside II, and Safflower Yellow, which have shown promising results in animal models of acute CNS injuries, including ischemic stroke, cerebral ischemia-reperfusion injury, intracerebral hemorrhage, subarachnoid hemorrhage, traumatic brain injury, and spinal cord injury. Among these, Baicalin and its precursor Baicalein stand out due to extensive research and favorable outcomes in acute injury models. Mechanistically, these flavonoids not only regulate the Nrf2/ARE pathway and activate GPX4/GSH-related antioxidant pathways but also modulate iron metabolism proteins, thereby alleviating iron overload and inhibiting ferroptosis. While flavonoids show promise as ferroptosis inhibitors for CNS diseases, especially in acute injury settings, further studies are needed to evaluate their efficacy, safety, pharmacokinetics, and blood-brain barrier penetration for clinical application.

Prevention of Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage-Summary of Existing Clinical Evidence

The 2023 International Subarachnoid Hemorrhage Conference identified a need to provide an up-to-date review on prevention methods for delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage and highlight areas for future research. A PubMed search was conducted for key factors contributing to development of delayed cerebral ischemia: anesthetics, antithrombotics, cerebrospinal fluid (CSF) diversion, hemodynamic, endovascular, and medical management. It was found that there is still a need for prospective studies analyzing the best methods for anesthetics and antithrombotics, though inhaled anesthetics and antiplatelets were found to have some advantages. Lumbar drains should increasingly be considered the first line of CSF diversion when applicable. Finally, maintaining euvolemia before and during vasospasm is recommended as there is no evidence supporting prophylactic spasmolysis or angioplasty. There is accumulating observational evidence, however, that intra-arterial spasmolysis with refractory DCI might be beneficial in patients not responding to induced hypertension. Nimodipine remains the medical therapy with the most support for prevention.

Effectiveness of Cerebrospinal Fluid Lumbar Drainage Among Patients with Aneurysmal Subarachnoid Hemorrhage: An Updated Systematic Review and Meta-Analysis

INTRODUCTION

Cerebral vasospasm in patients after aneurysmal subarachnoid hemorrhage (aSAH) continues to be a major source of morbidity despite significant clinical and basic science research. The removal of blood and its degradation products from the subarachnoid space through prophylactic lumbar drainage (LD) is a favorable option. However, several studies have delivered conflicting conclusions on its efficacy after aSAH.

METHODS

Systematic searches of Medline, Embase, and Cochrane Central Register of Controlled Trials were performed. The primary outcome was a good functional outcome (modified Rankin scale score, 0-2). Secondary outcomes included symptomatic vasospasm, secondary cerebral infarction, and mortality.

RESULTS

A total of 14 studies reporting on 2473 patients with aSAH were included in the meta-analysis. Compared with the non-LD group, no significant differences were found in the rates of good functional outcomes in the LD group at discharge to 1 month (risk ratio [RR], 1.28; 95% confidence interval [CI], 0.64-2.58) or at 6 months (RR, 1.12; 95% CI, 0.97-1.41). These findings were consistent in the subgroup analyses of only randomized controlled trials or observational studies. LD was associated with lower rates of symptomatic vasospasm (RR, 0.61; 95% CI, 0.48-0.77), secondary cerebral infarction (RR, 0.59; 95% CI, 0.45-0.79), and mortality at discharge to 1 month (RR, 0.58; 95% CI, 0.41-0.82). The effect on mortality diminished at 6 months (RR, 0.70; 95% CI, 0.34-1.45). However, when analyzing only randomized controlled trials, the benefit of LD on lower rates of mortality continued even at 6 months (RR, 0.75; 95% CI, 0.58-0.99).

CONCLUSIONS

For aSAH patients, the use of LD is associated with benefits in the rates of vasospasm, secondary cerebral infarctions, and mortality, without an increased risk of adverse events.

Construction and verification of risk predicting models to evaluate the possibility of hydrocephalus following aneurysmal subarachnoid hemorrhage

BACKGROUND

Hydrocephalus following a ruptured aneurysm portends a poor prognosis. The authors aimed to establish a nomogram to predict the risk of hydrocephalus after aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

A total of 421 patients with aSAH who were diagnosed by digital subtraction angiography in The General Hospital of Northern Theater Command center from January 2020 to June 2021 were screened to establish the training cohort. An additional 135 patients who enrolled between July 2021 and May 2022 were used for the validation cohort. Variate difference analysis and stepwise logistic regression (model A) and univariate and multivariate logistic regressions (model B) were respectively used to construct two models. Then, the net reclassification improvement (NRI), integrated discrimination improvement (IDI), and receiver operating characteristic (ROC) curve were used to compare the predictive abilities of the two models. Finally, two nomograms were constructed and externally validated.

RESULTS

After screening, 556 patients were included. The area under the ROC curve of models A and B in the training cohort were respectively 0.884 (95 % confidence interval [CI]: 0.847-0.921) and 0.834 (95 % CI: 0.787-0.881). The prediction ability of the model A was superior to model B (NRI > 0, IDI > 0, p < 0.05). The C-index of models A and B was 0.8835 and 0.8392, respectively. Regarding clinical usefulness, the two models offered a net benefit with a threshold probability of between 0.12 and 1 in the decision curve analysis, suggesting that the two models can accurately predict hydrocephalus events.

CONCLUSIONS

Both models have good prediction accuracy. Compared with model B, model A has better discrimination and calibration. Further, the easy-to-use nomogram can help neurosurgeons to make rapid clinical decisions and apply early treatment measures in high-risk groups, which ultimately benefits patients.

Ferroptosis as a Therapeutic Target in Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a cerebrovascular disorder with significant mortality and morbidity. Neural injury in SAH is mediated through a variety of pathophysiological processes. Currently available treatments are either nonspecific in targeting the basic pathophysiological mechanisms that result in neural damage in SAH, or merely focus on vasospasm. Ferroptosis is a type of programmed iron dependent cell death, which has received attention due to its possible role in neural injury in SAH. Herein, we review how intracellular iron overload mediates the production of reactive free radicals and lipid peroxidation through a variety of biochemical pathways in SAH. This in turn results in induction of ferroptosis, as well as exacerbation of vasospasm. We also discuss several therapeutic agents that have been shown to inhibit ferroptosis through targeting different steps of the process. Such agents have proven effective in ameliorating vasospasm, neural damage, and neurobehavioral outcomes in animal models of SAH. Human studies to test the safety and efficacy of intrathecal or parenteral administration of the inhibitors of ferroptosis in improving outcomes of SAH patients are warranted. There are currently a few ongoing clinical trials pursuing this therapeutic concept, the results of which will be critical to determine the value of ferroptosis as a novel therapeutic target in SAH.

Subarachnoid Blood Clearance and Aneurysmal Subarachnoid Hemorrhage Outcomes: A Retrospective Review

BACKGROUND

Delayed cerebral ischemia (DCI) continues to be a significant contributor to morbidity and mortality following aneurysmal subarachnoid hemorrhage (aSAH). Subarachnoid blood and its degradation products have been implicated in DCI, and faster blood clearance has been hypothesized to confer better outcomes. This study evaluates the relationship between blood volume and its clearance on DCI (primary outcome) and location at 30 days (secondary outcome) after aSAH.

METHODS

This is a retrospective review of adult patients presenting with aSAH. Hijdra sum scores (HSS) were assessed independently for each computed tomography (CT) scan of patients with available scans on post-bleed days 0-1 and 2-10. This cohort was used to evaluate the course of subarachnoid blood clearance (group 1). A subset of patients in the first cohort with available CT scans on both post-bleed days 0-1 and post-bleed days 3-4 composed the second cohort (group 2). This group was used to evaluate the association between initial subarachnoid blood (measured via HSS post-bleed days 0-1) and its clearance (measured via percentage reduction [HSS %Reduction] and absolute reduction [HSS-Abs-Reduction] in HSS between days 0-1 and 3-4) on outcomes. Univariable and multivariable logistic regression models were used to identify outcome predictors.

RESULTS

One hundred fifty-six patients were in group 1, and 72 patients were in group 2. In this cohort, HSS %Reduction was associated with decreased risk of DCI in univariate (odds ratio [OR] = 0.700 [0.527-0.923], p = 0.011) and multivariable (OR = 0.700 [0.527-0.923], p = 0.012) analyses. Higher HSS %Reduction was significantly more likely to have better outcomes at 30 days in the multivariable analysis (OR = 0.703 [0.507-0.980], p = 0.036). Initial subarachnoid blood volume was associated with outcome location at 30 days (OR = 1.331 [1.040-1.701], p = 0.023) but not DCI (OR = 0.945 [0.780-1.145], p = 0.567).

CONCLUSIONS

Early blood clearance after aSAH was associated with DCI (univariable and multivariable analyses) and outcome location at 30 days (multivariable analysis). Methods facilitating subarachnoid blood clearance warrant further investigation.

Feasibility of Prompt Lumbar Drainage in Patients with Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Numerous studies have shown that continuous lumbar drainage (LD) reduces spontaneous subarachnoid hemorrhage (SAH)-related complications, decreasing the incidence of cerebral vasospasm, delayed cerebral ischemia , and hydrocephalus in patients treated with coiling or clipping, but performing LD before securing the aneurysm is still controversial. Our hospital has been implementing prompt LD for several years, and we present the results in this paper.

METHODS

Between January 2014 and December 2020, a total of 438 patients with SAH were included in this retrospective study. The indication for prompt LD was aneurysmal SAH of modified Fisher grade III or higher without dense intraventricular hemorrhage with obstructive hydrocephalus requiring extraventricular drainage or large intracranial hemorrhage requiring immediate decompression. Prompt LD was performed for 229 patients with SAH, and the control group included 209 patients. We compared in-hospital mortality and vasospasm or hydrocephalus occurrence and procedure-related complications between the two groups.

RESULTS

The in-hospital mortality rate was 7.4% for patients with prompt LD and 14.4% for patients without LD, and the difference was significant (P = 0.019). Vasospasm occurred in 10% of patients with prompt LD and 16.7% of controls (P = 0.039). Hydrocephalus requiring extraventricular drainage occurred in 10.9% of the LD group and 28.7% of the control group (P < 0.001). Rebleeding occurrence was 3.1% in the prompt LD group and 5.7% in the non-LD group (P = 0.168). Cerebrospinal fluid infection occurred in 0.4% of the prompt LD group and 1.4% of controls(P = 0.272).

CONCLUSIONS

Prompt LD is a feasible option for treating patients with selective aneurysmal SAH.

The effect of postoperative early lumbar drainage on delayed fever after cerebellopontine angle tumour surgery: study protocol for a randomized controlled trial

BACKGROUND

Postoperative fever is one of the common complications in neurosurgery, and intracranial aseptic inflammation and infection are important risk factors. Continuous drainage of cerebrospinal fluid (CSF) via lumbar drainage (LD) is often used in the treatment of postoperative intracranial infection or aseptic inflammation. Compared with the previously reported placement of LD after the onset of meningitis symptoms, we designed this randomized controlled trial (RCT) to evaluate the effectiveness and safety of early drainage (1st day postoperation) of CSF using the preset lumbar cistern to prevent delayed fever (fever occurred after the third day postoperation) or reduce its treatment time after cerebellopontine angle (CPA) tumour surgery.

METHODS

Patients suffering from CPA tumours and who underwent resection of the tumour with an intraoperative dura opening time > 4 h are recruited for this study. The study is a 2-arm RCT to compare the early LD group and the no early LD group. Postoperative duration and rate of delayed fever and postoperative length of stay (LOS), as the main outcomes, will be compared in the two groups.

DISCUSSION

Here, we present the study design of a prospective RCT to evaluate the safety and efficacy of using preoperative preset LD to treat or reduce postoperative delayed fever.

TRIAL REGISTRATION

China Clinical Trial Registry ChiCTR2100049057. Registered on July 20, 2021.

Review of the Prevention and Treatment of Hydrocephalus After Aneurysmal Subarachnoid Hemorrhage

Hydrocephalus following a ruptured aneurysm portends a poor prognosis. Patients have to face the risk of infection and shunt obstruction after shunt surgery, which may require a second procedure and greatly reduce the quality of life for survivors. It is crucial to minimize the incidence of hydrocephalus and reduce cerebrospinal fluid shunt dependency. This article reviews current interventions before and after hydrocephalus formation after aneurysmal subarachnoid hemorrhage, focusing on the relationships between treatment options and the incidence of postoperative hydrocephalus, management of cerebrospinal fluid drainage and shunt dependent hydrocephalus, and advocates for the combination of prevention and treatment to develop individualized treatment plans for patients.

The Benefits and Feasibility of External Lumbar Cerebrospinal Fluid Drainage for Cerebral Vasospasm in Patients with Aneurysmal Subarachnoid Hemorrhage: Meta-Analysis and Trial Sequential Analysis

OBJECTIVE

Cerebral vasospasm after aneurysmal subarachnoid hemorrhage is a main cause contributing to poor outcomes. Removal of blood from the subarachnoid may decrease development of cerebral vasospasm. The purpose of this study is to determine the effect of lumbar cerebrospinal fluid (CSF) drainage on cerebral vasospasm and related complications through meta-analysis and trial sequential analysis (TSA).

METHODS

A systematic search of the literature was performed. Case-control studies of the effects of external lumbar drainage in patients with subarachnoid hemorrhage were included. The association between lumbar drain and vasospasm, cerebral infarction, subsequent treatment, and mortality were evaluated.

RESULTS

Eleven of 122 articles were included in the meta-analysis. Lumbar CSF drainage reduces occurrence of vasospasm and related complications. In meta-analysis, the pooled odds ratio for symptomatic vasospasm, cerebral infarct, endovascular treatment for vasospasm, and mortality was 0.40 (95% confidence interval [CI], 0.31-0.51; P = 0.00001), 0.47 (95% CI, 0.35-0.62; P < 0.0001), 0.29 (95% CI, 0.18-0.46; P < 0.0001), and 0.41, (95% CI, 0.23-0.74; P = 0.003), respectively, compared with the non-lumbar drainage group. In TSA, the cumulative Z line crossed α-spending boundaries and reached the required sample size in analysis of symptomatic vasospasm and endovascular treatment for vasospasm.

CONCLUSIONS

Lumbar CSF drainage can decrease symptomatic vasospasm, cerebral infarction, subsequent endovascular treatment, and mortality. Through TSA, the accuracy and reliability of the effect of lumbar CSF drainage-related cerebral vasospasm and endovascular treatment are increased. Further studies of the association between lumbar drain and cerebral infarction and mortality are required to confirm the generalization of the results.

Targeting Hemoglobin to Reduce Delayed Cerebral Ischemia After Subarachnoid Hemorrhage

Delayed cerebral ischemia (DCI) continues to be a sequela of aneurysmal subarachnoid hemorrhage (aSAH) that carries significant morbidity and mortality. Aside from nimodipine, no therapeutic agents are available to reduce the incidence of DCI. Pathophysiologic mechanisms contributing to DCI are poorly understood, but accumulating evidence over the years implicates several factors. Those have included microvessel vasoconstriction, microthrombosis, oxidative tissue damage, and cortical spreading depolarization as well as large vessel vasospasm. Common to these processes is red blood cell leakage into the cerebrospinal fluids (CSF) and subsequent lysis which releases hemoglobin, a central instigator in these events. This has led to the hypothesis that early blood removal may improve clinical outcome and reduce DCI. This paper will provide a narrative review of the evidence of hemoglobin as an instigator of DCI. It will also elaborate on available human data that discuss blood clearance and CSF drainage as a treatment of DCI. Finally, we will address a recent novel device that is currently being tested, the Neurapheresis CSF Management System™. This is an automated dual-lumen lumbar drainage system that has an option to filter CSF and return it to the patient.

Lumbar Drainage After Aneurysmal Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis

OBJECTIVE

This study reviews the use of lumbar drains (LDs) after aneurysmal subarachnoid hemorrhage (aSAH) and compares the outcomes to those associated with external ventricular drains (EVDs) and controls.

METHODS

A comprehensive search of the literature was performed. English language studies with a sample size of more than 10 patients were included. One-arm and 2-arm meta-analyses were designed to compare external drainage groups. Random-effects models, heterogeneity measures, and risk of bias were calculated.

RESULTS

Seventeen studies were included in the meta-analysis. The 2-arm meta-analysis comparing the LD to no drainage after aSAH found a significant improvement in the postoperative modified Rankin Scale (mRS) score (0-2) within 1 month of hospital discharge in the LD group (P = 0.003), a lower mortality rate (P = 0.03), fewer cases of clinical vasospasm (P = 0.007), and a lower incidence of ischemic stroke or delayed ischemic neurological deficits (P = 0.003). When the LD was compared to EVDs, a significant improvement in the postoperative mRS score (0-2) within 1 month of discharge was found in the LD group (P < 0.001). In the LD group, rebleeding occurred in 15 (3.4%) cases and meningitis occurred in 50 (4.7%) cases.

CONCLUSIONS

Compared with patients without cerebrospinal fluid drainage, patients with the LD after aSAH had lower mortality rates, lower risk of clinical vasospasm, and lower risk of ischemic stroke, and they were more likely to have an mRS score of 0-2 within 1 month of discharge. Compared with patients with EVDs, patients with the LD were more likely to have an mRS score of 0-2 within 1 month of discharge.

Criteria for Cerebrospinal Fluid Diversion in Retractorless Sphenoid Wing Meningioma Surgery: A Technical Report

Objective  Sphenoid wing meningiomas (SWMs) can present surgical challenges, in that they are often obscured by overlying brain, encase critical neurovascular structures, and obliterate cerebrospinal fluid (CSF) cisterns. While brain retraction can enable access, its use can have potentially deleterious effects. We report the benefits and outcomes of the criteria we have developed for use of cerebrospinal diversion to perform retractorless surgery for SWMs. Design  Technical report. Setting  Yale School of Medicine and Yale New Haven Hospital. Participants  Between May, 2019 and December, 2020, ten consecutive patients were included who met the presented criteria for SWM surgery with preoperative lumbar drain (LD) placement. Main Outcome Measures  Length of hospital stay, surgical complications, and extent of resection. Results  We have developed the following criteria for LD placement in patients with SWMs such that LDs are preoperatively placed in patients with tumors with one or more of the following criteria: (1) medial location along the sphenoid wing, (2) vascular encasement resulting in obliteration of the optic carotid cistern and/or proximal sylvian fissure, and/or (3) the presence of associated edema. CSF release, after craniotomy and sphenoid wing removal, allowed for optimization of exposure, leading to the maximal safe extent of tumor resection without brain retraction or any complications. Conclusions  Preoperative LD placement is effective in allowing for maximal extent of resection of SWMs and may be considered in cases where local CSF release is not possible. This technique is useful in those tumors located more medially, with encasement of the vasculature and/or associated with edema.

Postoperative Early Lumbar Drainage Can Reduce the Duration of Fever or Infection in Patients with Complicated Intracranial Tumors after a Long Operation Time

Background

Intracranial fever or infection is one of the common complications after craniotomy, especially for complicated intracranial tumors such as deep skull base tumors.

Objective

We used early cerebrospinal fluid (CSF) drainage with a preplaced lumbar drainage (LD) tube after surgery and observed whether this procedure could reduce the rate and duration of fever or infection.

Material and Methods

The authors conducted a retrospective study of 142 patients who underwent complicated intracranial tumor surgery with no less than four hours of dural opening at the Center of Neurosurgery of Tangdu Hospital. The LD group underwent preoperative LD placement, intraoperative CSF release and postoperative continuous drainage, but the control group received routine craniotomy without preoperative LD. The primary outcomes included the rate, duration, and hospital length of stay (LOS) for patients with fever or infection after surgery, as compared between the two groups. The second outcome included complications related to LD and the rate of postoperative CSF leakage.

Results

There were 22 patients in the LD group and 23 patients in the control group who presented with delayed fever, which was supposed to be caused by intracranial infection or aseptic inflammation. The median duration of delayed fever in the LD group was obviously lower than that in the control group (7.762 ± 3.129 days vs 11.73 ± 5.239 days), and there was a statistically significant difference (P = 0.0046). In addition, there was a significant reduction in the median postoperative LOS (12 [8,10,15,21] days in the LD group vs 15 [9,13,20,28] days in the controls). Moreover, there was no significant difference in complications related to LD between the two groups. Three patients with brain herniation were observed in the LD group compared with one patient in the control group. All four patients had contemporary mild-to-moderate neurologic disorders after surgery or conservative treatment. Additionally, the rate of CSF leakage in the LD group was 5.41% (4/74), which was lower than that in the control group (8/68, [11.76%]), although there was no significant difference (P = 0.174).

Conclusions

For patients receiving complicated intracranial lesions following a long operation time, postoperative early LD was beneficial for the treatment of patients with fever or infection. It not only reduced the duration of infection or fever in postoperative patients but also decreased the postoperative LOS. We should minimize the complications related to LD by careful and standardized LD and management processes, and ensure the effectiveness and safety of this treatment.

Prediction of Lumbar Drainage-Related Meningitis Based on Supervised Machine Learning Algorithms

Background

Lumbar drainage is widely used in the clinic; however, forecasting lumbar drainage-related meningitis (LDRM) is limited. We aimed to establish prediction models using supervised machine learning (ML) algorithms.

Methods

We utilized a cohort of 273 eligible lumbar drainage cases. Data were preprocessed and split into training and testing sets. Optimal hyper-parameters were archived by 10-fold cross-validation and grid search. The support vector machine (SVM), random forest (RF), and artificial neural network (ANN) were adopted for model training. The area under the operating characteristic curve (AUROC) and precision-recall curve (AUPRC), true positive ratio (TPR), true negative ratio (TNR), specificity, sensitivity, accuracy, and kappa coefficient were used for model evaluation. All trained models were internally validated. The importance of features was also analyzed.

Results

In the training set, all the models had AUROC exceeding 0.8. SVM and the RF models had an AUPRC of more than 0.6, but the ANN model had an unexpectedly low AUPRC (0.380). The RF and ANN models revealed similar TPR, whereas the ANN model had a higher TNR and demonstrated better specificity, sensitivity, accuracy, and kappa efficiency. In the testing set, most performance indicators of established models decreased. However, the RF and AVM models maintained adequate AUROC (0.828 vs. 0.719) and AUPRC (0.413 vs. 0.520), and the RF model also had better TPR, specificity, sensitivity, accuracy, and kappa efficiency. Site leakage showed the most considerable mean decrease in accuracy.

Conclusions

The RF and SVM models could predict LDRM, in which the RF model owned the best performance, and site leakage was the most meaningful predictor.

Effect of stress-induced hyperglycemia after non-traumatic non-aneurysmal subarachnoid hemorrhage on clinical complications and functional outcomes

Background

Despite having an overall benign course, non‐traumatic non‐aneurysmal subarachnoid hemorrhage (naSAH) is still accompanied by a risk of clinical complications and poor outcomes. Risk factors and mechanisms of complications and poor outcomes after naSAH remain unknown. Our aim was to explore the effect of stress‐induced hyperglycemia (SIH) on complication rates and functional outcomes in naSAH patients.

Methods

We retrospectively reviewed patients with naSAH admitted to our institution between 2013 and 2018. SIH was identified according to previous criterion. Symptomatic vasospasm, delayed cerebral infarction, and hydrocephalus were identified as main complications. Outcomes were reviewed using a modified Rankin Scale (mRS) at discharge, 3 months, and 12 months. A statistical analysis was conducted to reveal the associations of SIH with complications and outcomes.

Results

A total of 244 naSAH patients were included in the cohort with 74 (30.3%) SIH. After adjusting for age, gender, hypertension, Hunt and Hess (HH) grade, modified Fisher Scale (mFS), intraventricular hemorrhage (IVH), and subarachnoid blood distribution, SIH was significantly associated with symptomatic vasospasm (p < 0.001, 12.176 [4.904–30.231]), delayed cerebral infarction (p < 0.001, 12.434 [3.850–40.161]), hydrocephalus (p = 0.008, 5.771 [1.570–21.222]), and poor outcome at 12 months (p = 0.006, 5.506 [1.632–18.581]), whereas the correlation between SIH and poor outcome at discharge (p = 0.064, 2.409 [0.951–6.100]) or 3 months (p = 0.110, 2.029 [0.852–4.833]) was not significant. Incorporation of SIH increased the area under curve (AUC) of ROC in the combined model for predicting symptomatic vasospasm (p = 0.002), delayed cerebral infarction (p = 0.024), hydrocephalus (p = 0.037), and 12‐month poor outcome (p = 0.087).

Conclusions

SIH is a significant and independent risk factor for symptomatic vasospasm, delayed cerebral infarction, hydrocephalus, and long‐term poor outcome in naSAH patients. Identifying SIH early after naSAH is important for decision‐making and treatment planning.

A new perspective on cerebrospinal fluid dynamics after subarachnoid hemorrhage: From normal physiology to pathophysiological changes

Knowledge about the dynamic metabolism and function of cerebrospinal fluid (CSF) physiology has rapidly progressed in recent decades. It has traditionally been suggested that CSF is produced by the choroid plexus and drains to the arachnoid villi. However, recent findings have revealed that the brain parenchyma produces a large portion of CSF and drains through the perivascular glymphatic system and meningeal lymphatic vessels into the blood. The primary function of CSF is not limited to maintaining physiological CNS homeostasis but also participates in clearing waste products resulting from neurodegenerative diseases and acute brain injury. Aneurysmal subarachnoid hemorrhage (SAH), a disastrous subtype of acute brain injury, is associated with high mortality and morbidity. Post-SAH complications contribute to the poor outcomes associated with SAH. Recently, abnormal CSF flow was suggested to play an essential role in the post-SAH pathophysiological changes, such as increased intracerebral pressure, brain edema formation, hydrocephalus, and delayed blood clearance. An in-depth understanding of CSF dynamics in post-SAH events would shed light on potential development of SAH treatment options. This review summarizes and updates the latest physiological characteristics of CSF dynamics and discusses potential pathophysiological changes and therapeutic targets after SAH.

Update on intrathecal management of cerebral vasospasm: a systematic review and meta-analysis

OBJECTIVE

Aneurysmal subarachnoid hemorrhage (aSAH) accounts for a relatively small portion of strokes but has the potential to cause permanent neurological deficits. Vasospasm with delayed ischemic neurological deficit is thought to be responsible for much of the morbidity associated with aSAH. This has illuminated some treatment options that have the potential to target specific components of the vasospasm cascade. Intrathecal management via lumbar drain (LD) or external ventricular drain (EVD) offers unique advantages in this patient population. The aim of this review was to provide an update on intrathecal vasospasm treatments, emphasizing the need for larger-scale trials and updated protocols using data-driven evidence.

METHODS

A search of PubMed, Ovid MEDLINE, and Cochrane databases included the search terms (subarachnoid hemorrhage) AND (vasospasm OR delayed cerebral ischemia) AND (intrathecal OR intraventricular OR lumbar drain OR lumbar catheter) for 2010 to the present. Next, a meta-analysis was performed of select therapeutic regimens. The primary endpoints of analysis were vasospasm, delayed cerebral ischemia (DCI), cerebral infarction, and functional outcome.

RESULTS

Twenty-nine studies were included in the analysis. There were 10 studies in which CSF drainage was the primary experimental group. Calcium channel antagonists were the focus of 7 studies. Fibrinolytics and other vasodilators were each examined in 6 studies. The meta-analysis included studies examining CSF drainage via LD (n = 4), tissue plasminogen activator in addition to EVD (n = 3), intraventricular nimodipine (n = 2), and cisternal magnesium (n = 2). Results showed that intraventricular nimodipine decreased vasospasm (OR 0.59, 95% CI 0.37-0.94; p = 0.03). Therapies that significantly reduced DCI were CSF drainage via LD (OR 0.47, 95% CI 0.25-0.88; p = 0.02) and cisternal magnesium (OR 0.27, 95% CI 0.07-1.02; p = 0.05). CSF drainage via LD was also found to significantly reduce the incidence of cerebral infarction (OR 0.35, 95% 0.24-0.51; p < 0.001). Lastly, functional outcome was significantly better in patients who received CSF drainage via LD (OR 2.42, 95% CI 1.39-4.21; p = 0.002).

CONCLUSIONS

The authors' results showed that intrathecal therapy is a safe and feasible option following aSAH. It has been shown to attenuate cerebral vasospasm, reduce the incidence of DCI, and improve clinical outcome. The authors support the use of intrathecal management in the prevention and rescue management of cerebral vasospasm. More randomized controlled trials are warranted to determine the best combination of pharmaceutical agents and administration route in order to formulate a standardized treatment approach.

Therapeutic Approaches for Cerebrovascular Dysfunction After Aneurysmal Subarachnoid Hemorrhage: An Update and Future Perspectives

Aneurysmal subarachnoid hemorrhage (aSAH) is a severe subtype of stroke occurring at a relatively young age with a significant socioeconomic impact. Treatment of aSAH includes early aneurysm exclusion, intensive care management, and prevention of complications. Once the aneurysm rupture occurs, blood spreading within the subarachnoid space triggers several molecular pathways causing early brain injury and delayed cerebral ischemia. Pathophysiologic mechanisms underlying brain injury after aSAH are not entirely characterized, reflecting the difficulties in identifying effective therapeutic targets for patients with aSAH. Although the improvements of the last decades in perioperative management, early diagnosis, aneurysm exclusion techniques, and medical treatments have increased survival, vasospasm and delayed cerebral infarction are associated with high mortality and morbidity. Clinical practice can rely on a few specific therapeutic agents, such as nimodipine, a calcium-channel blocker proved to reduce severe neurologic deficits in these patients. Therefore, new pharmacologic approaches are needed to improve the outcome of this life-threatening condition, as well as a tailored rehabilitation plan to maintain the quality of life in aSAH survivors. Several clinical trials are investigating the efficacy and safety of emerging drugs, such as magnesium, clazosentan, cilostazol, interleukin 1 receptor antagonists, deferoxamine, erythropoietin, and nicardipine, and continuous lumbar drainage in the setting of aSAH. This narrative review focuses on the most promising therapeutic interventions after aSAH.

Inhibition of caspase-1-mediated inflammasome activation reduced blood coagulation in cerebrospinal fluid after subarachnoid haemorrhage

Background

Neuroinflammation and blood coagulation responses in cerebrospinal fluid (CSF) contribute to the poor outcome associated with subarachnoid haemorrhage (SAH). We explored the role of caspase-1-mediated inflammasome activation on extrinsic blood coagulation in CSF after SAH.

Methods

Post-SAH proteomic changes and correlation between caspase-1 with extrinsic coagulation factors in human CSF after SAH were analysed. Time course and cell localisation of brain inflammasome and extrinsic coagulation proteins after SAH were explored in a rat SAH model. Pharmacological inhibition of caspase-1 via VX-765 was used to explore the role of caspase-1 in blood clearance and CSF circulation after SAH in rats. Primary astrocytes were used to evaluate the role of caspase-1 in haemoglobin-induced pyroptosis and tissue factor (TF) production/release.

Findings

Neuroinflammation and blood coagulation activated after SAH in human CSF. The caspase-1 levels significantly correlated with the extrinsic coagulation factors. The activated caspase-1 and extrinsic coagulation initiator TF was increased on astrocytes after SAH in rats. VX-765 attenuated neurological deficits by accelerating CSF circulation and blood clearance through inhibiting pyroptotic neuroinflammation and TF-induced fibrin deposition in the short-term, and improved learning and memory capacity by preventing hippocampal neuronal loss and hydrocephalus in the long-term after SAH in rats. VX-765 reduced haemoglobin-induced pyroptosis and TF production/release in primary astrocytes.

Interpretation

Inhibition of caspase-1 by VX-765 appears to be a potential treatment against neuroinflammation and blood coagulation in CSF after SAH.

Funding

This study was supported by National Institutes of Health of United States of America, and National Natural Science Foundation of China.

Delayed transient obstructive hydrocephalus after cerebral aneurysm rupture: A case report

RATIONALE

Obstructive hydrocephalus (OH) frequently occurs in patients with a ruptured cerebral aneurysm (CA), and it may lead to severe neurological deficits, including life-threatening brain herniation. OH generally occurs in the early stage of CA rupture, rather than in the late stage, and rarely resolves without therapy.

PATIENT CONCERNS

A 64-year-old woman with a ruptured anterior communicating artery aneurysm was treated with coil embolization. Nineteen days after her CA rupture, because of the delayed transient OH, she experienced a dramatic cycle in consciousness over 9 hours: wakefulness-drowsiness-coma-drowsiness-wakefulness.

DIAGNOSIS

The patient was diagnosed with delayed transient obstructive hydrocephalus, which is a very rare condition.

INTERVENTIONS

Mannitol was administered to reduce intracranial pressure.

OUTCOMES

The patient was discharged from the hospital 30 days after admission, with a final GCS score of 15 and without weaknesses. At follow-up 2 months after discharge, brain CT revealed non-recurrence of hydrocephalus.

LESSONS

A blood clot of any size in the ventricle is likely to lead to obstructive hydrocephalus. Prolonged bed rest for IVH patients may help to reduce the incidence of delayed OH.

Complications of external cerebrospinal fluid drainage in aneurysmal subarachnoid haemorrhage

Background

The need for external cerebrospinal fluid (CSF) drains in aneurysmal subarachnoid haemorrhage (aSAH) patients is common and might lead to additional complications.

Objective

A relation between the presence of an external CSF drain and complication risk is investigated.

Methods

A prospective complication registry was analysed retrospectively. We included all adult aSAH patients admitted to our academic hospital between January 2016 and January 2018, treated with an external CSF drain. Demographic data, type of external drain used, the severity of the aSAH and complications, up to 30 days after drain placement, were registered. Complications were divided into (1) complications with a direct relation to the external CSF drain and (2) complications that could not be directly related to the use of an external CSF drain referred to as medical complications

Results

One hundred and forty drains were implanted in 100 aSAH patients. In total, 112 complications occurred in 59 patients. Thirty-six complications were drain related and 76 were medical complications. The most common complication was infection (n = 34). Drain dislodgement occurred 16 times, followed by meningitis (n = 11) and occlusion (n = 9). A Poisson model showed that the mean number of complications raised by 2.9% for each additional day of drainage (95% CI: 0.6–5.3% p = 0.01).

Conclusion

Complications are common in patients with aneurysmal subarachnoid haemorrhage of which 32% are drain-related. A correlation is present between drainage period and the number of complications. Therefore, reducing drainage period could be a target for further improvement of care.

Ferroptosis: An emerging therapeutic target in stroke

Stroke is a disastrous neurological disease with high morbidity and mortality. The mechanism of the pathological process is extremely complicated and unclear. Although many basic studies have confirmed molecular mechanism of brain injury after stroke, these studies have not yet translated into treatment and clinical application. Ferroptosis is a form of cell death that is distinct from necrosis, apoptosis, and autophagy morphologically and biochemically and is characterized by iron-dependent accumulation of lipid peroxides. Despite ferroptosis being first identified in cancer cells, it was recently revealed to also be a significant factor in the pathological process of stroke. A better understanding of ferroptosis in stroke may provide us with better therapeutic targets to treat this devastating disease. Here, we systematically summarized the current mechanism of ferroptosis and reviewed the current studies regarding the relationship between ferroptosis and stroke.

Programmed Cell Deaths and Potential Crosstalk With Blood-Brain Barrier Dysfunction After Hemorrhagic Stroke

Hemorrhagic stroke is a life-threatening neurological disease characterized by high mortality and morbidity. Various pathophysiological responses are initiated after blood enters the interstitial space of the brain, compressing the brain tissue and thus causing cell death. Recently, three new programmed cell deaths (PCDs), necroptosis, pyroptosis, and ferroptosis, were also found to be important contributors in the pathophysiology of hemorrhagic stroke. Additionally, blood-brain barrier (BBB) dysfunction plays a crucial role in the pathophysiology of hemorrhagic stroke. The primary insult following BBB dysfunction may disrupt the tight junctions (TJs), transporters, transcytosis, and leukocyte adhesion molecule expression, which may lead to brain edema, ionic homeostasis disruption, altered signaling, and immune infiltration, consequently causing neuronal cell death. This review article summarizes recent advances in our knowledge of the mechanisms regarding these new PCDs and reviews their contributions in hemorrhagic stroke and potential crosstalk in BBB dysfunction. Numerous studies revealed that necroptosis, pyroptosis, and ferroptosis participate in cell death after subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH). Endothelial dysfunction caused by these three PCDs may be the critical factor during BBB damage. Also, several signaling pathways were involved in PCDs and BBB dysfunction. These new PCDs (necroptosis, pyroptosis, ferroptosis), as well as BBB dysfunction, each play a critical role after hemorrhagic stroke. A better understanding of the interrelationship among them might provide us with better therapeutic targets for the treatment of hemorrhagic stroke.

Haptoglobin genotype and outcome after aneurysmal subarachnoid haemorrhage

OBJECTIVE

After aneurysmal subarachnoid haemorrhage (aSAH), extracellular haemoglobin (Hb) in the subarachnoid space is bound by haptoglobin, neutralising Hb toxicity and helping its clearance. Two exons in the HP gene (encoding haptoglobin) exhibit copy number variation (CNV), giving rise to HP1 and HP2 alleles, which influence haptoglobin expression level and possibly haptoglobin function. We hypothesised that the HP CNV associates with long-term outcome beyond the first year after aSAH.

METHODS

The HP CNV was typed using quantitative PCR in 1299 aSAH survivors in the Genetics and Observational Subarachnoid Haemorrhage (GOSH) Study, a retrospective multicentre cohort study with a median follow-up of 18 months. To investigate mediation of the HP CNV effect by haptoglobin expression level, as opposed to functional differences, we used rs2000999, a single nucleotide polymorphism associated with haptoglobin expression independent of the HP CNV. Outcome was assessed using modified Rankin and Glasgow Outcome Scores. SAH volume was dichotomised on the Fisher grade. Haemoglobin-haptoglobin complexes were measured in cerebrospinal fluid (CSF) of 44 patients with aSAH and related to the HP CNV.

RESULTS

The HP2 allele associated with a favourable long-term outcome after high-volume but not low-volume aSAH (multivariable logistic regression). However rs2000999 did not predict outcome. The HP2 allele associated with lower CSF haemoglobin-haptoglobin complex levels. The CSF Hb concentration after high-volume and low-volume aSAH was, respectively, higher and lower than the Hb-binding capacity of CSF haptoglobin.

CONCLUSION

The HP2 allele carries a favourable long-term prognosis after high-volume aSAH. Haptoglobin and the Hb clearance pathway are therapeutic targets after aSAH.

The role of haptoglobin and hemopexin in the prevention of delayed cerebral ischaemia after aneurysmal subarachnoid haemorrhage: a review of current literature

Delayed cerebral ischaemia (DCI) after aneurysmal subarachnoid haemorrhage (aSAH) is a major cause of mortality and morbidity. The pathophysiology of DCI after aSAH is thought to involve toxic mediators released from lysis of red blood cells within the subarachnoid space, including free haemoglobin and haem. Haptoglobin and hemopexin are endogenously produced acute phase proteins that are involved in the clearance of these toxic mediators. The aim of this review is to investigate the pathophysiological mechanisms involved in DCI and the role of both endogenous as well as exogenously administered haptoglobin and hemopexin in the prevention of DCI.