Pathophysiology of Delayed Cerebral Ischemia After Subarachnoid Hemorrhage: A Review

The pivotal role of microglia in injury and the prognosis of subarachnoid hemorrhage

Subarachnoid hemorrhage leads to a series of pathological changes, including vascular spasm, cellular apoptosis, blood-brain barrier damage, cerebral edema, and white matter injury. Microglia, which are the key immune cells in the central nervous system, maintain homeostasis in the neural environment, support neurons, mediate apoptosis, participate in immune regulation, and have neuroprotective effects. Increasing evidence has shown that microglia play a pivotal role in the pathogenesis of subarachnoid hemorrhage and affect the process of injury and the prognosis of subarachnoid hemorrhage. Moreover, microglia play certain neuroprotective roles in the recovery phase of subarachnoid hemorrhage. Several approaches aimed at modulating microglia function are believed to attenuate subarachnoid hemorrhage injury. This provides new targets and ideas for the treatment of subarachnoid hemorrhage. However, an in-depth and comprehensive summary of the role of microglia after subarachnoid hemorrhage is still lacking. This review describes the activation of microglia after subarachnoid hemorrhage and their roles in the pathological processes of vasospasm, neuroinflammation, neuronal apoptosis, blood-brain barrier disruption, cerebral edema, and cerebral white matter lesions. It also discusses the neuroprotective roles of microglia during recovery from subarachnoid hemorrhage and therapeutic advances aimed at modulating microglial function after subarachnoid hemorrhage. Currently, microglia in subarachnoid hemorrhage are targeted with TLR inhibitors, nuclear factor-κB and STAT3 pathway inhibitors, glycine/tyrosine kinases, NLRP3 signaling pathway inhibitors, Gasdermin D inhibitors, vincristine receptor α receptor agonists, ferroptosis inhibitors, genetic modification techniques, stem cell therapies, and traditional Chinese medicine. However, most of these are still being evaluated at the laboratory stage. More clinical studies and data on subarachnoid hemorrhage are required to improve the treatment of subarachnoid hemorrhage.

One-year outcome and quality of life of patients with subarachnoid hemorrhage admitted to intensive care unit: a single-center retrospective pilot study

Patients admitted to intensive care unit (ICU) after non-traumatic subarachnoid hemorrhage (SAH) represent a group with distinctive characteristics and few data are available on long-term outcome in this population. We conducted a single-center retrospective study in an Italian intensive care unit. All patients with non-traumatic SAH (ICD-9-CM Diagnosis Code 430) admitted to ICU were included. Disability and quality of life were evaluated via telephone interview after 12-15 months after initial bleeding using GOSE and EuroQoL, respectively. Baseline and clinical course characteristics were analyzed to evaluate relation with poor outcome defined as GOSE ≤ 3. Final population consisted of 38 patients. Twenty-four patients (63.2%) had favorable outcome (GOSE ≥ 4). Among 29 patients (76.3%) who survived at 1 year, median EQ-5D Index was 0.743 (IQR 0.287), while median EQ-VAS was 74.79 (IQR 18.5). Median EQ-5D Index and median EQ-VAS were higher among patients with favorable outcome (EQ-5D Index p = 0.037, EQ-VAS p = 0.003). Among baseline characteristics, only HH scale showed a significant relation with disability at one year (p = 0.033). Between complications occurred during ICU-stay only early HICP was related with unfavorable outcome (p = 0.028). Higher HH scale and early HICP were related with unfavorable outcome. Among patients with unfavorable outcome, quality of life has a broad range of variability, and this result should be taken into account when reporting patient-centered outcomes.

Multifaceted role of thrombin in subarachnoid hemorrhage: Focusing on cerebrospinal fluid circulation disorder

Subarachnoid hemorrhage (SAH) is a severe neurological condition characterized by high morbidity and mortality. The unfavorable prognosis of SAH is closely associated with early brain injury (EBI) and delayed cerebral ischemia (DCI), wherein thrombin plays a role as part of the secondary injury components following hemorrhage in these two pathological processes. Additionally, thrombin contributes to disruptions in the circulation of cerebrospinal fluid (CSF), thereby giving rise to a spectrum of sequelae following SAH, including cerebral edema, hydrocephalus, cognitive impairments, and depressive symptoms. This review aims to provide a comprehensive understanding of the pathological role of thrombin in EBI, DCI, and CSF circulation following SAH, with a specific focus on its impact on the glymphatic-meningeal lymphatic system-a crucial mechanism for waste clearance and neurohomeostatic regulation. Additionally, this review offers an overview of current pharmacological interventions and treatment modalities targeting pathogenic mechanisms, aiming to mitigate brain injury and promote neurological recovery post-SAH.

Relationship between cumulative blood pressure exposure within the early brain injury time window and delayed cerebral ischemia and rebleeding in patients with aneurysmal subarachnoid hemorrhage after aneurysm clipping: a retrospective study

Delayed cerebral ischemia, one of the most common complications following aneurysmal subarachnoid hemorrhage, was strongly related to poor patient outcomes. However, there are currently no clear guidelines to provide clinical guidance for post-craniotomy management. Our research aims to explore the association between cumulative blood pressure exposure during the early brain injury phase and the occurrence of delayed cerebral infarction and rebleeding following surgical aneurysm clipping. All baseline characteristics of the patients were meticulously recorded. We collected blood pressure data 25 times in 48 h after surgery for subsequent analysis. Cumulative blood pressure exposure is calculated by the product of the time spent below a specific blood pressure threshold and the cumulative exposure time. The principal outcome is the incidence of Delayed Cerebral Infarction, while the secondary outcome pertains to postoperative rebleeding. Logistic regression was utilized to examine the relationship. The cumulative exposure to mean arterial pressure at and below 85 mmHg demonstrated a significant association with DCI occurrence. However, no significant statistical correlation was found between hypertensive exposure and rebleeding events. The results from the sensitivity analysis remained consistent, and the lack of significant interactions further supports the robustness of the study findings. The identified threshold of 85 mmHg could potentially represent a critical blood pressure management parameter for post-surgical aneurysm clipping patients. These findings merit further investigation through larger prospective clinical trials.

Intrathecal Nicardipine After Aneurysmal Subarachnoid Hemorrhage: A Scoping Review

Intrathecal nicardipine (ITN) is an investigational therapy for cerebral vasospasm (CVS) and delayed cerebral ischemia (DCI) in patients with aneurysmal subarachnoid hemorrhage (aSAH). The objective of this scoping review was to characterize the current state of the literature and map the current available evidence, examine research methodology, clarify key concepts and definitions in the literature, report procedural characteristics, identify and analyze knowledge gaps, and serve as a precursor for future systematic reviews, meta-analyses, and randomized controlled trials. An electronic search for studies on ITN for the treatment of CVS and DCI in patients with aSAH was conducted in accordance with published standards. A total of 390 studies were identified by the search. After inclusion criteria were applied, 20 studies were identified for analysis. The identified studies included a total of 976 patients with aSAH who received ITN for the treatment of CVS and DCI. One randomized controlled trial, two prospective observational studies, nine retrospective observational studies, seven retrospective case series, and one case report met inclusion criteria. Study designs, drug administration, dosing regimens, drug concentrations, pharmacokinetics, patient selection, duration of therapy, outcome measures, adverse event monitoring, and definitions of CVS and DCI used are synthesized and discussed. Despite advances in the care of patients with aSAH, CVS and DCI remain leading causes of morbidity and mortality, and ITN represents a potential therapy to help prevent and treat this disease process. With one published randomized controlled trial on one method of administration, one trial underway on a second method of administration, and numerous heterogeneous and primarily retrospective studies published to date, future study with an emphasis on homogenizing study design and outcomes measured is needed to better understand this potential therapy.

Remote ischaemic conditioning for neurological disorders-a systematic review and narrative synthesis

INTRODUCTION

Remote ischaemic conditioning (RIC) refers to the use of controlled transient ischemic and reperfusion cycles, commonly of the upper or lower limb, to mitigate cellular damage from ischaemic injury. Preclinical studies demonstrate that RIC may have a neuroprotective effect and therefore could represent a novel therapeutic option in the management of neurological disorders. The aim of this review is to comprehensively describe the current clinical evidence of RIC in neurological disorders.

METHODS

A computerised search of EMBASE and OVID MEDLINE was conducted from 2002 to October 2023 for randomised controlled trials (RCTs) investigating RIC in neurological diseases.

RESULTS

A total of 46 different RCTs in 12 different neurological disorders (n = 7544) were included in the analysis. Conditions included acute ischaemic stroke, symptomatic intracranial stenosis and vascular cognitive impairment. The most commonly used RIC protocol parameters in the selected studies were as follows: cuff pressure at 200 mmHg (27 trials), 5-min cycle length (42 trials), 5 cycles of ischaemia and reperfusion (24 trials) and the application to the upper limb unilaterally (23 trials).

CONCLUSIONS

The comprehensive analysis of the included studies reveals promising results regarding the safety and therapeutic effect of RIC as an option for managing neurological diseases. Particularly, the strongest evidence supports its potential use in chronic stroke patients and vascular cognitive impairment. The neuroprotective effects of RIC, as demonstrated in preclinical studies, suggest that this therapeutic approach could extend its benefits to various other diseases affecting the nervous system. However, to establish the efficacy of RIC across different neurological disorders, further trials with larger sample sizes and more diverse patient populations are warranted. Upcoming trials are expected to provide valuable evidence that will not only confirm the efficacy of RIC in neurological disease management but also help identify the most optimal RIC regimen for specific conditions.

Optimal cerebral perfusion pressure during induced hypertension and its impact on delayed cerebral infarction and functional outcome after subarachnoid hemorrhage

Disturbed cerebral autoregulation (CA) increases the dependency of cerebral blood flow (CBF) on cerebral perfusion pressure (CPP). Thus, induced hypertension (IHT) is used to prevent secondary ischemic events. The pressure reactivity index (PRx) assesses CA and can determine the optimal CPP (CPPopt). This study investigates CPPopt in patients with subarachnoid hemorrhage (SAH) treated with IHT and its impact on delayed cerebral infarction and functional outcome. This is a retrospective observational study including SAH patients treated between 2012 and 2020. PRx defines the correlation coefficient of intracranial pressure (ICP) and the mean arterial pressure (MAP). The CPP corresponding to the lowest PRx-value describes CPPopt. Primary outcome parameters were deleayed cerebral infarction and functional outcome. In patients without IHT, higher deviations of measured CPP from CPPopt were associated with delayed cerebral infarction (p = 0.001). Longer time spent with a CPP below the calculated CPPopt during IHT led to an increased risk of developing delayed cerebral infarction (r = 0.39, p = 0.002). A larger deviation of measured CPP from CPPopt correlated with an unfavorable outcome in patients treated with IHT (p = 0.04) and without IHT (p = 0.0007). Patients with severe aneurysmal SAH may benefit from an individualized CPP management and the calculation of CPPopt may help to guide IHT.

Threshold hemoglobin level for delayed cerebral ischemia: A single-center retrospective analysis

Background

Delayed cerebral ischemia (DCI) occurs in approximately 20%-30 % of patients with subarachnoid hemorrhage (SAH). This is the most common complication of SAH and has a high mortality rate. In the present study, we investigated the relationship between hemoglobin (Hb) values and DCI and aimed to determine a cutoff Hb value to be used as a predictor of DCI.

Methods

A total of 259 patients who were followed up for aneurysmal SAH at the Neurosurgery Clinic of Health Sciences University Dışkapı Yıldırım Beyazıt Training and Research Hospital were included in our study. The patients were categorized into three groups according to Hb levels, low: <10 g/dl, moderate:10-13 g/dl, and high: >13 g/dl, and the relationship between Hb value and DCI and clinical outcomes was examined. Further, the cutoff Hb value for predicting DCI was determined by receiver operating characteristics (ROC) curve analysis.

Results

Statistical analyses revealed that patients with low Hb levels of <10 g/dl had a higher frequency of DCI than those with Hb levels of <10.75 g/dl. In addition, pairwise analyses based on the determined cutoff value revealed that patients with Hb levels <10.75 g/dl experienced DCI more frequently.

Conclusion

This study aimed to determine the utility of Hb levels as a predictor of DCI by examining its risk factors. The cutoff Hb level determined here is an important predictive factor for DCI, and the results provide promising evidence in term of early detection of DCI.

Use of dual intraventricular vasodilators for refractory cerebral vasospasm in a pediatric patient with traumatic subarachnoid hemorrhage: A case report

PURPOSE

Subarachnoid hemorrhage (SAH) is a rare but life-threatening clinical event for pediatric patients. Cerebral vasospasm is a common complication of SAH that often leads to poor outcomes. This case report describes the use of dual intraventricular (IVT) vasodilators in a pediatric patient.

SUMMARY

An 11-year-old male presented with traumatic diffuse SAH and cerebral vasospasm. Despite treatment with IVT nicardipine, intravenous (IV) milrinone by continuous infusion, enteral nimodipine, and intraarterial verapamil and milrinone given during digital subtraction angiography, transcranial Doppler (TCD) mean velocities continued to rise. IVT milrinone was then added to IVT nicardipine and IV milrinone. The combination of IVT nicardipine, IV milrinone, and rescue therapy with IVT milrinone was continued for a total of 7 days. TCD mean velocities decreased into the mild to moderate range within 2 days of the patient receiving this combined regimen and remained globally low thereafter.

CONCLUSION

This case illustrates the potential benefit of using dual IVT vasodilators to improve outcomes for pediatric patients with refractory cerebral vasospasm.

Quantitative analysis of HSV‑1 shedding as a predictor of cerebral vasospasm severity in patients with subarachnoid hemorrhage

Cerebral vasospasm (CV) is a critical determinant of outcomes in patients with aneurysmal subarachnoid hemorrhage (aSAH). Despite advances in neurocritical care, modifiable risk factors for CV remain poorly understood, and identifying them could significantly enhance patient management and treatment strategies. The present study explored the potential link between the reactivation of herpes simplex virus type 1 (HSV-1), a common resident virus in cranial nerves, and CV severity. It was hypothesized that higher HSV-1 viral load in saliva may be associated with increased CV severity. Saliva samples were collected on days 4, 7, 10 and 14 post-aSAH, and HSV-1 DNA levels were measured using quantitative PCR. CV severity was assessed using the Lindegaard ratio (LR), with an LR >3 considered the diagnostic threshold for CV. A total of 36 patients were enrolled, and 139 saliva samples were collected. HSV-1 DNA was detected in 19.4% of samples (27/139), and 44% of patients (16/36) developed CV. HSV-1 seropositive patients made up 88.9% (32/36) of the cohort, with 50% exhibiting viral shedding during the study period. None of the HSV-1 seronegative patients (11.1%, 4/36) exhibited viral shedding or developed CV. Regression analysis showed a positive association between HSV-1 viral load and CV severity, with viral load explaining 27.8% of the variability (P=0.005). Age was also significant, with older patients experiencing less severe CV (P<0.001). Supervised machine learning identified viral load thresholds that aligned with standard LR values for moderate and severe CV. While the small sample size and observational design limit the generalizability of the results, these findings suggested that earlier detection and intervention for CV could be informed by assessing HSV-1 serostatus and monitoring viral activity through saliva samples or other non-invasive methods, highlighting the need for larger, controlled studies to validate these results.

The impact of systolic blood pressure reduction on aneurysm re-bleeding in subarachnoid hemorrhage: A systematic review and meta-analysis

BACKGROUND

Preventing early aneurysm rebleeding is crucial in the management of aneurysmal subarachnoid hemorrhage (SAH). Lowering systolic blood pressure (SBP) has been proposed as a potential strategy, but the evidence remains inconclusive. This systematic review and meta-analysis aimed to determine if a specific SBP target could reduce the risk of aneurysm rebleeding prior to treatment.

METHODS

Electronic databases were systematically searched for studies comparing SBP between SAH patients with and without aneurysm rebleeding before surgical treatment. Data on SBP values, patient characteristics, and rebleeding events were extracted. Meta-analyses were performed to pool mean SBP differences and odds ratios (ORs) for rebleeding at different SBP cut-offs.

RESULTS

Ten studies were included in the systematic review. Pooled data from the included studies showed that the mean SBP was higher in the rebleeding group (mean difference 5.89, 95 % CI 1.94 to 9.85). SBP ≤160 mmHg was associated with lower rebleeding risk (OR 0.30, 95 % CI 0.14 to 0.65). However, substantial heterogeneity and limitations in study designs and definitions were noted.

CONCLUSIONS

This meta-analysis suggests that SAH patients with rebleeding may present with higher SBP. However, the findings should be interpreted cautiously due to study limitations. Future prospective studies with standardized definitions and comprehensive data collection are needed to elucidate the complex relationship between blood pressure dynamics and rebleeding risk in SAH.

Multi-targeted olink proteomics analyses of cerebrospinal fluid from patients with aneurysmal subarachnoid hemorrhage

BACKGROUND

The complexity of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH) may require the simultaneous analysis of variant types of protein biomarkers to describe it more accurately. In this study, we analyzed for the first time the alterations of cerebrospinal fluid (CSF) proteins in patients with aSAH by multi-targeted Olink proteomics, aiming to reveal the pathophysiology of DCI and provide insights into the diagnosis and treatment of aSAH.

METHODS

Six aSAH patients and six control patients were selected, and CSF samples were analyzed by Olink Proteomics (including 96-neurology panel and 96-inflammation panel) based on Proximity Extension Assay (PEA). Differentially expressed proteins (DEPs) were acquired and bioinformatics analysis was performed.

RESULTS

PCA analysis revealed better intra- and inter-group reproducibility of CSF samples in the control and aSAH groups. 23 neurology-related and 31 inflammation-relevant differential proteins were identified. In the neurology panel, compared to controls, the up-regulated proteins in the CSF of SAH patients predominantly included macrophage scavenger receptor 1 (MSR1), siglec-1, siglec-9, cathepsin C (CTSC), cathepsin S (CTSS), etc. Meanwhile, in the inflammation group, the incremental proteins mainly contained interleukin-6 (IL-6), MCP-1, CXCL10, CXCL-9, TRAIL, etc. Cluster analysis exhibited significant differences in differential proteins between the two groups. GO function enrichment analysis hinted that the differential proteins pertinent to neurology in the CSF of SAH patients were mainly involved in the regulation of defense response, vesicle-mediated transport and regulation of immune response; while the differential proteins related to inflammation were largely connected with the cellular response to chemokine, response to chemokine and chemokine-mediated signaling pathway. Additionally, in the neurology panel, KEGG enrichment analysis indicated that the differential proteins were significantly enriched in the phagosome, apoptosis and microRNAs in cancer pathway. And in the inflammation panel, the differential proteins were mainly enriched in the chemokine signaling pathway, viral protein interaction with cytokine and cytokine receptor and toll-like receptor signaling pathway.

CONCLUSIONS

These identified differential proteins reveal unique pathophysiological characteristics secondary to aSAH. Further characterization of these proteins and aberrant pathways in future research could enable their application as potential therapeutic targets and biomarkers for DCI after aSAH.

Association of the C-reactive protein/albumin ratio with the prognosis of Aneurysmal Subarachnoid Hemorrhage: A systematic review

The C-Reactive Protein/Albumin Ratio (CAR) is being studied as a potential predictor of severe outcomes in various diseases. Our study aimed to review current evidence on the prognostic value of CAR in patients with aneurysmal subarachnoid hemorrhage (aSAH). We conducted a systematic search in PubMed, Embase, Scopus, Web of Science, and Google Scholar up to April 2023 and assessed the risk of bias using the NewCastle-Ottawa tool. A narrative synthesis was performed, and the GRADE system was used to evaluate the certainty of the evidence. Out of 534 articles, 4 were selected. We found that a higher CAR level is moderately associated with a lower score on the Glasgow Outcome Scale at 3 months and a higher incidence of in-hospital mortality. However, no significant association was found with the modified Rankin scale or delayed cerebral ischemia. Although the evidence is limited, CAR could be a useful tool for predicting poor prognosis in aSAH patients, but more prospective studies are needed to determine optimal cut-off points and include CAR in long-term prognostic models.

Trajectory clustering of immune cells and its association with clinical outcomes after aneurysmal subarachnoid hemorrhage

Background and purpose

The immune response following aneurysmal subarachnoid hemorrhage (aSAH) can exacerbate secondary brain injury and impact clinical outcomes. As the immune response after aSAH is a dynamic process, we aim to track and characterize immune cell trajectories over time to identify patterns associated with various clinical outcomes.

Methods

In this retrospective single-center study of patients with aSAH, we analyzed immune cell count trajectories, including neutrophil, monocyte, and lymphocyte counts, collected from day 1 to day 14. These trajectories were classified into four distinct clusters utilizing the k-means longitudinal clustering method. A comprehensive multivariable analysis was performed to explore the associations of these immune cell clusters with various clinical outcomes. These outcomes included a Modified Rankin Scale score (mRS) of 3 to 6, indicative of poor functional outcomes, along with complications including shunt dependency, vasospasm, and secondary cerebral infarction.

Results

In this study, 304 patients with aSAH were analyzed. The trajectories of immune cell counts, including neutrophils, monocytes, and lymphocytes, were successfully categorized into four distinct clusters for each immune cell type. Within neutrophil clusters, both persistent neutrophilia and progressive neutrophilia were associated with poor functional outcomes, shunt dependency, and vasospasm, with resolving neutrophilia showing a lesser degree of these associations. Within monocyte clusters, early monocytosis was associated with vasospasm, whereas delayed monocytosis was associated with shunt dependency. Within lymphocyte clusters, both early transient lymphopenia and early prolonged lymphopenia were associated with poor functional outcomes.

Conclusion

Our study demonstrates that distinct immune cell trajectories post-aSAH, identified through unsupervised clustering, are significantly associated with specific clinical outcomes. Understanding these dynamic immune responses may provide key insights with potential for future therapeutic strategies.

Phloretin attenuates inflammation induced by subarachnoid hemorrhage through regulation of the TLR2/MyD88/NF-kB pathway

Subarachnoid hemorrhage (SAH), a stroke subtype associated with high mortality, is closely linked to neuroinflammation. Phloretin, a naturally occurring flavonoid abundant in fruits, possesses anti-inflammatory properties. However, its specific role in SAH remains unclear. Therefore, we aimed to investigate the potential role of phloretin in SAH. We established in vitro and in vivo SAH models to assess the effects of phloretin. Subsequently, utilizing SAH-related public datasets from the GEO database, we identified key genes associated with SAH and investigated the potential mechanism of action of phloretin. Our findings reveal that phloretin significantly improves prognostic outcomes and mitigates inflammation in SAH mice. Moreover, our results suggest that phloretin mitigates neuroinflammation by inhibiting the TLR2/MYD88/NF-κB pathway.

Neuroradiological diagnosis and therapy of cerebral vasospasm after subarachnoid hemorrhage

BACKGROUND

Cerebral damage after aneurysmal subarachnoid hemorrhage (SAH) results from various, sometimes unrelated causes. After the initial hemorrhage trauma with an increase in intracranial pressure, induced vasoconstriction, but also microcirculatory disturbances, inflammation and pathological electrophysiological processes (cortical spreading depolarization) can occur in the course of the disease, resulting in delayed cerebral ischemia (DCI). In the neuroradiological context, cerebral vasospasm (CVS) remains the focus of diagnostic imaging and endovascular therapy as a frequent component of the genesis of DCI.

METHODS

The amount of blood leaked during aneurysm rupture (which can be detected by CT, for example) correlates with the occurrence and severity of CVS. CT perfusion is then an important component in determining the indication for endovascular spasm therapies (EST). These include intra-arterial drug administration (also as long-term microcatheter treatment) and mechanical procedures (balloon angioplasty, vasodilatation using other instruments such as stent retrievers, stenting).

CONCLUSION

This review summarizes the current findings on the diagnosis and treatment of CVS after aneurysmal SAH from a neuroradiological perspective, taking into account the complex and up-to-date international literature.

KEY POINTS

· Vasospasm is a frequent component of the multifactorial genesis of delayed cerebral ischemia after SAH and remains the focus of diagnosis and treatment in the neuroradiological context.. · The initial extent of SAH on CT is associated with the occurrence and severity of vasospasm.. · CT perfusion is an important component in determining the indication for endovascular spasm therapy.. · Endovascular spasm therapies include local administration of medication (also as long-term therapies with microcatheters) and mechanical procedures (balloon angioplasty, dilatation using other devices such as stent retreivers, stenting)..

CITATION FORMAT

· Neumann A, Schacht H, Schramm P. Neuroradiological diagnosis and therapy of cerebral vasospasm after subarachnoid hemorrhage. Fortschr Röntgenstr 2024; 196: 1125 - 1133.

Advances and controversies in meningeal biology

The dura, arachnoid and pia mater, as the constituent layers of the meninges, along with cerebrospinal fluid in the subarachnoid space and ventricles, are essential protectors of the brain and spinal cord. Complemented by immune cells, blood vessels, lymphatic vessels and nerves, these connective tissue layers have held many secrets that have only recently begun to be revealed. Each meningeal layer is now known to have molecularly distinct types of fibroblasts. Cerebrospinal fluid clearance through peripheral lymphatics and lymph nodes is well documented, but its routes and flow dynamics are debated. Advances made in meningeal immune functions are also debated. This Review considers the cellular and molecular structure and function of the dura, arachnoid and pia mater in the context of conventional views, recent progress, and what is uncertain or unknown. The hallmarks of meningeal pathophysiology are identified toward developing a more complete understanding of the meninges in health and disease.

Admission albumin-globulin ratio associated with delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage

Background

Despite the widespread use in ischemic stroke, cancer, and malnutrition, the predictive ability of serum albumin to globulin ratio (A/G) among patients suffering from aneurysmal subarachnoid hemorrhage (aSAH) remains unknown. This study aimed to determine if serum A/G ratio is associated with the occurrence of delayed cerebral ischemia (DCI) after aSAH.

Methods

We retrospectively viewed the medical records of aSAH patients from 08/2017 to 08/2022. Serum albumin and globulin laboratory test results were collected within 24 hours after admission. Serum A/G were dichotomized based on whether the DCI occurred. Logistic regression was used to determine the predictors of DCI. The relationship between serum A/G and the occurrence of DCI was analyzed with receiver operating characteristic(ROC) curve.

Results

A total of 363 eligible patients with aSAH were included in the study, among which DCI occurred in 87 patients(23.97%). Serum A/G[OR=2.720, 95%CI (1.190-6.270), P=0.018], non-surgical[OR=0.228, 95%CI (0.065-0.621), P=0.008], lactate dehydrogenase[OR=1.004, 95%CI (1.000-1.008), P=0.029], P[OR=0.354, 95%CI (0.130-0.926), P=0.038], plasma fibrinogen[OR=1.266, 95%CI (1.019-1.583), P=0.035] were associated with the occurrence of DCI. ROC showed that serum A/G, non-surgical, LDH, P, plasma fibrinogen could predict the occurrence of DCI in aSAH patients with values 0.575, 0.560, 0.602, 0.571 and 0.539 for serum A/G, non-surgical, LDH, P, plasma fibrinogen, respectively.

Conclusions

In conclusion, serum A/G levels are correlated with DCI in individuals with aSAH, and high serum A/G levels on admission may be associated with the occurrence of DCI.

Cerebrolysin in Patients Diagnosed with Subarachnoid Hemorrhage-The Results of an Observational Cohort Study

Background: Subarachnoid hemorrhage (SAH) is associated with high mortality and a high level of disability. Progress in surgical and endovascular techniques has lowered the mortality rate in patients with SAH. However, many patients are left with neurological impairment. Objectives: In our study we wanted to examine the impact of Cerebrolysin on treatment results in patients with SAH diagnosis. Methods: The data of 47 patients, divided into Cerebrolysin (26) and non-Cerebrolysin (21) group were included. We examined the correlation between Cerebrolysin administration and additional Amantadine treatment or neuromonitoring, craniectomy, and endovascular treatment and its impact on the Glasgow Outcome Scale (GOS) score, length of stay (LOS), and mortality. Results: Our study shows that Cerebrolysin improves the mortality rate in combination with neuromonitoring in a group of patients with severe SAH. It does not affect the raw values of GOS or LOS in patients with SAH. Conclusions: Further studies with larger patient groups are needed to investigate the role of Cerebrolysin as an additional treatment in SAH.

Trajectory of mean platelet volume changes after aneurysmal subarachnoid hemorrhage in patients with or without delayed cerebral ischemia

The morbidity of aneurysmal subarachnoid hemorrhage (aSAH) remains high, particularly because of secondary cerebral lesions that significantly aggravate the primary lesions. The main type of secondary lesions is delayed cerebral ischemia (DCI), in which platelets (PLT) appear to play a key role. Mean platelet volume (MPV) is an indirect marker of platelet activation. We aimed to determine the individual trajectories of MPV over time in patients with and without DCI during the course of aSAH. This is a single-center, retrospective, longitudinal analysis of individual trajectories of MPV over time, in a cohort of aSAH patients included in the Prospective, Observational Registry of Patient with Subarachnoid Hemorrhage in Neurocritical Care Unit (ProReSHA). A mixed-effects linear regression model was used to compare the trajectories of MPV and MPV/PLT ratio between patients who developed a DCI and those who did not. A total of 3634 MPV values were collected in 587 patients. The analysis of MPV as a function of DCI occurrence showed a significant difference in the trajectory over time between patients with DCI and those without, with an estimate of 0.02 (95%CI 0.01, 0.04, p = 0.009). The analysis of the MPV/PLT ratio as a function of DCI occurrence and other covariates showed a significant difference in the trajectory over time only for patients with a modified Fisher score less than 3, with an estimate of -0.59 (95%CI: -0.94, -0.23, p = 0.001). The individual trajectories of MPV over time differ between patients with DCI and those without. However, MPV values vary greatly over time and between patients. Thus it does not appear as a reliable biomarker for stratifying patients based on their specific risk of developing DCI. ClinicalTrials.gov identifier: (NCT02890004), registered in August 2016.

PD-1 mediates microglia polarization via the MAPK signaling pathway to protect blood-brain barrier function during cerebral ischemia/reperfusion

BACKGROUND

Cerebral ischemia is characterized by its rapid onset and high rates of recurrence, morbidity, and mortality, with blood-brain barrier (BBB) permeability playing a vital role in brain injury. Therefore, it is important to understand the molecular mechanism which regulates the BBB during cerebral ischemia.

MATERIALS AND METHODS

An in vitro model of oxygen-glucose deprivation (OGD) and an in vivo model of cerebral ischemia/reperfusion (I/R) were constructed. PD-1 overexpression vectors and vectors containing si-RNA were transfected and injected into in vitro and in vivo models. Western blotting, real-time quantitative PCR (qPCR), immunofluorescence (IF) analysis, and immunohistochemical staining were employed to evaluate the expression levels of programmed cell death-1 (PD-1), microglia M1 and M2 biomarkers, and tight junction proteins. Flow cytometry and ELISA were used to measure the levels of pro-inflammatory cytokines. The BBB permeability of brain tissues was evaluated by Evans blue dye (EBD) extravasation and transendothelial electrical resistance (TEER). Brain water content was measured to assess the extent of inflammatory exudation. The infarct volume and neurological severity score (NSS) were used to assess the severity of brain injury. Brain cell apoptosis was assessed by the TUNEL assay and hematoxylin-eosin (H&E) staining.

RESULTS

PD-1 helped to convert the microglia M1 phenotype to the M2 phenotype and to reduce BBB permeability both in vitro and in vivo. Overexpression of PD-1 promoted a shift of the M1 phenotype to the M2 phenotype and reduced BBB permeability via the ERK and p38 MAPK signaling pathways. PD-1 reduced inflammatory exudation, BBB permeability, cell apoptosis, and brain injury in vivo.

CONCLUSION

Our present study verified that PD-1 exerts an anti-inflammatory effect by converting the microglia M1 phenotype to the M2 phenotype, reducing BBB permeability, and thereby relieves brain injury caused by cerebral ischemia. PD-1 is potential therapeutic target for brain injury caused by cerebral ischemia.

Enteral Cilostazol and High-Dose Intravenous Albumin in Aneurysmal Subarachnoid Hemorrhage Patients With Refractory Cerebral Ischemia

Cerebral ischemia associated with vasospasm in patients with aneurysmal subarachnoid hemorrhage (aSAH) requires a multifaceted approach. We report the use of the combination of enteral cilostazol and intravenous (IV) high-dose albumin in aSAH patients with cerebral ischemia refractory to other accepted pharmacologic and endovascular treatments. Three aSAH patients who developed cerebral ischemic symptoms despite treatment with oral nimodipine and endovascular measures (i.e., intraarterial vasodilators and balloon angioplasty) were treated with enteral cilostazol (200 mg/day) and one or more doses of IV (25%) albumin (1.25 g per kg over eight hours). The patients were monitored by serial neurological examinations, transcranial Doppler imaging (TCDI) ultrasound, computed tomographic angiography (CTA), and perfusion (CTP) scans. Three patients (ages 58, 67, and 56 years) developed symptomatic cerebral ischemia and vasospasm following an aSAH. Due to limited angiographic response to endovascular treatment, including intraarterial vasodilators with or without balloon angioplasty, IV (25%) albumin and enteral cilostazol were administered. CT angiogram and perfusion 2-3 days post-treatment demonstrated resolution of the perfusion deficits and angiographic vasospasm. Concurrently, TCDI demonstrated improved vasospasm and clinical examination demonstrated resolution of neurological deficits. None of the patients required any additional treatments for cerebral ischemia. A combination of oral cilostazol and IV high dose (25%) albumin was associated with amelioration of angiographic vasospasm, reduction of tissue perfusion deficits, and clinical improvement of aSAH patients with severe refractory cerebral ischemia.

Tranexamic Acid Use in the Surgical Arena: A Narrative Review

INTRODUCTION

Tranexamic acid (TXA) is a potent antifibrinolytic drug that inhibits the activation of plasmin by plasminogen. While not a new medication, TXA has quickly gained traction across a variety of surgical subspecialties to prevent and treat bleeding. Knowledge on the use of this drug is essential for the modern surgeon to continue to provide excellent care to their patients.

METHODS

A comprehensive review of the PubMed database was conducted of articles published within the last 10 y (2014-2024) relating to TXA and its use in various surgical subspecialties. Seminal studies regarding the use of TXA older than 10 y were included from the author's archives.

RESULTS

Indications for TXA are not limited to trauma alone, and TXA is utilized across a variety of surgical subspecialties from neurosurgery to hepatic surgery to control hemorrhage. Overall, TXA is well tolerated with common dose-dependent adverse effects, including headache, nasal symptoms, dizziness, nausea, diarrhea, and fatigue. More severe adverse events are rare and easily mitigated by not exceeding a dose of 50 mg/kg.

CONCLUSIONS

The administration of TXA as an adjunct to treat trauma saves lives. The ability of TXA to induce seizures is dose dependent with identifiable risk factors, making this serious adverse effect predictable. As for the potential for TXA to cause thrombotic events, uncertainty remains. If this association is proven to be real, the risk will likely be small, since the use of TXA is still advantageous in most situations because of its efficacy for a more common concern, bleeding.

Neurobehavioral Impairments Predict Specific Cerebral Damage in Rat Model of Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a severe form of stroke that can cause unpredictable and diffuse cerebral damage, which is difficult to detect until it becomes irreversible. Therefore, there is a need for a reliable method to identify dysfunctional regions and initiate treatment before permanent damage occurs. Neurobehavioral assessments have been suggested as a possible tool to detect and approximately localize dysfunctional cerebral regions. In this study, we hypothesized that a neurobehavioral assessment battery could be a sensitive and specific method for detecting damage in discrete cerebral regions following SAH. To test this hypothesis, a behavioral battery was employed at multiple time points after SAH induced via an endovascular perforation, and brain damage was confirmed via postmortem histopathological analysis. Our results demonstrate that impairment of sensorimotor function accurately predict damage in the cerebral cortex (AUC 0.905; sensitivity 81.8%; specificity 90.9%) and striatum (AUC 0.913; sensitivity 90.1%; specificity 100%), while impaired novel object recognition is a more accurate indicator of damage to the hippocampus (AUC 0.902; sensitivity 74.1%; specificity 83.3%) than impaired reference memory (AUC 0.746; sensitivity 72.2%; specificity 58.0%). Tests for anxiety-like and depression-like behaviors predict damage to the amygdala (AUC 0.900; sensitivity 77.0%; specificity 81.7%) and thalamus (AUC 0.963; sensitivity 86.3%; specificity 87.8%), respectively. This study suggests that recurring behavioral testing can accurately predict damage in specific brain regions, which could be developed into a clinical battery for early detection of SAH damage in humans, potentially improving early treatment and outcomes.

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.

Electroacupuncture enhances cerebral blood perfusion by inhibiting HIF-1α in rat subarachnoid hemorrhage

OBJECTIVE

Cerebral blood perfusion (CBP) reduction is a prevalent complication following subarachnoid hemorrhage (SAH) in clinical practice, often associated with long-term cognitive impairment and prognosis. Electroacupuncture (EA), a widely utilized traditional Chinese therapy for central nervous system disorders, has demonstrated promising therapeutic effects. This study aims to investigate the therapeutic potential of EA in restoring CBP in SAH rats and to explore the mechanisms involving HIF-1α in this process.

METHODS

Rats were randomly assigned to one of five groups, including Sham, SAH, EA, EA + Saline, and EA + dimethyloxallyl glycine (DMOG) groups. EA treatment was administered for 10 min daily, while DMOG were intraperitoneally injected. Behavioral tests, cerebral blood flow monitoring, vascular thickness measurement, western blotting, and immunofluorescence staining were conducted to assess the therapeutic effects of EA on cerebral blood flow.

RESULTS

SAH resulted in elevated levels of HIF-1α, endothelin (ET), ICAM-1, P-SELECTIN, E-SELECTIN, and decreased level of eNOS in the brain. This led to cerebral vasospasm, decreased CBF, and cognitive deficits in the rat SAH model. EA intervention downregulated the expression of HIF-1α, ET, ICAM-1, P-SELECTIN, and E-SELECTIN, while increasing eNOS expression. This alleviated cerebral vasospasm, restored CBF, and improved cognitive function. However, the administration of the HIF-1α stabilizer (DMOG) counteracted the therapeutic effects of EA.

CONCLUSION

EA promotes the recovery of cerebral blood flow after SAH injury, attenuates cerebral vasospasm, and accelerates the recovery of cognitive dysfunction, and its mechanism of action may be related to the inhibition of the HIF-1α signaling pathway.

Comparison of LVIS and Enterprise stent-assisted coiling embolization for ruptured intracranial aneurysms: a propensity score-matched cohort study

The role of a low-profile visualized intraluminal support stent (LVIS) and Enterprise in the treatment of unruptured intracranial aneurysms is well established. Although previous studies have investigated one single type of stent for the treatment of ruptured intracranial aneurysms (RIA), the safety and efficacy between the two types of stents has not been fully explored. Herein we conducted a study to compare the outcomes of the two stents for treatment of RIA. This is a prospective registry database of aneurysmal subarachnoid hemorrhage (aSAH) patients admitted to a single institution between 2018 and 2021. We collected patient baseline information, secondary complications, follow-up angiographic data, long-term prognostic outcomes, and conducted propensity score matching (PSM) analysis with 1:1 ratio and a multivariable logistic regression to compare the outcomes of the two types of stents. A total of 231 patients with RIAs were included in this study, with 108 treated using the LVIS device and 123 treated using the Enterprise device. Before PSM analysis, only the incidence of poor prognosis after 12 months was higher in the Enterprise group comparing to the LVIS group (20% vs. 10%, P = 0.049). After PSM analysis, there was a higher occurrence of delayed cerebral ischemia (DCI) in the Enterprise group compared to the LVIS group (odds ratio [OR] 3.95, 95% confidence interval [CI] [1.20-13.01], P = 0.024). However, no significant difference in prognosis was observed after PSM adjustment. Furthermore, subgroup analysis revealed that patients with female (P = 0.019), hypertension (P = 0.048), and anterior circulation aneurysms (P = 0.019) receiving the Enterprise device had a higher risk of DCI. The overall efficacy of LVIS and Enterprise in the treatment of RIA is comparable, while the incidence of DCI in the LVIS group is lower than that in the Enterprise group after PSM analysis. Registration number: NCT05738083 ( https://clinicaltrials.gov/ ).

Perfusion imaging for delayed cerebral ischemia detection in patients following ruptured aneurysmal subarachnoid hemorrhage: Interrater reliability assessment

BACKGROUND

Delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH) is associated with adverse neurological outcomes. Early and accurate diagnosis of DCI is crucial to prevent cerebral infarction. This study aimed to assess the diagnostic accuracy and interrater agreement of the visual assessment of neuroimaging perfusion maps to detect DCI in patients suspected of vasospasm after aSAH.

METHODS

In this case-control study, cases were adult aSAH patients with DCI who underwent magnetic resonance perfusion or computed tomography perfusion (CTP) imaging in the 24 h prior to digital subtraction angiography for vasospasm diagnosis. Controls were patients with dizziness and no aSAH on CTP imaging. Three independent raters, blinded to patients' clinical information, other neuroimaging studies, and angiographic results, visually assessed anonymized perfusion color maps to classify patients as either having DCI or not. Tmax delay was classified by symmetry into no delay, unilateral, or bilateral.

RESULTS

Perfusion imaging of 54 patients with aSAH and 119 control patients without aSAH was assessed. Sensitivities for DCI diagnosis ranged from 0.65 to 0.78, and specificities ranged from 0.70 to 0.87, with interrater agreement ranging from 0.60 (moderate) to 0.68 (substantial).

CONCLUSION

Visual assessment of perfusion color maps demonstrated moderate to substantial accuracy in diagnosing DCI in aSAH patients.

Modified Beer-Lambert algorithm to measure pulsatile blood flow, critical closing pressure, and intracranial hypertension

We introduce a frequency-domain modified Beer-Lambert algorithm for diffuse correlation spectroscopy to non-invasively measure flow pulsatility and thus critical closing pressure (CrCP). Using the same optical measurements, CrCP was obtained with the new algorithm and with traditional nonlinear diffusion fitting. Results were compared to invasive determination of intracranial pressure (ICP) in piglets (n = 18). The new algorithm better predicted ICP elevations; the area under curve (AUC) from logistic regression analysis was 0.85 for ICP ≥ 20 mmHg. The corresponding AUC for traditional analysis was 0.60. Improved diagnostic performance likely results from better filtering of extra-cerebral tissue contamination and measurement noise.

Delayed Cerebral Infarction After Aneurysmal Subarachnoid Hemorrhage: Location, Distribution Patterns, Infarct Load, and Effect on Outcome

BACKGROUND AND OBJECTIVES

Delayed cerebral ischemia (DCI) is one of the main contributing factors to poor clinical outcome after aneurysmal subarachnoid hemorrhage (SAH). Unsuccessful treatment can cause irreversible brain injury in the form of DCI-related infarction. We aimed to assess the association between the location, distribution, and size of DCI-related infarction in relation to clinical outcome.

METHODS

Consecutive patients with SAH treated at 2 university hospitals between 2014 and 2019 (Helsinki, Finland) and between 2006 and 2020 (Aachen, Germany) were included. Size of DCI-related infarction was quantitatively measured as absolute volume (in milliliters). In a semiquantitative fashion, infarction in 14 regions of interest (ROIs) according to a modified Alberta Stroke Program Early CT Score (ASPECTS) was noted. The association of infarction in these ROIs along predefined regions of eloquent brain, with clinical outcome, was assessed. For this purpose, 1-year outcome was measured by the Glasgow Outcome Scale (GOS) and dichotomized into favorable (GOS 4-5) and unfavorable (GOS 1-3).

RESULTS

Of 1,190 consecutive patients with SAH, 155 (13%) developed DCI-related infarction. One-year outcome data were available for 148 (96%) patients. A median overall infarct volume of 103 mL (interquartile range 31-237) was measured. DCI-related infarction was significantly associated with 1-year unfavorable outcome (odds ratio [OR] 4.89, 95% CI 3.36-7.34, p < 0.001). In patients with 1-year unfavorable outcome, vascular territories more frequently affected were left middle cerebral artery (affected in 49% of patients with unfavorable outcome vs in 30% of patients with favorable outcome; p = 0.029), as well as left (44% vs 18%; p = 0.003) and right (52% vs 14%; p < 0.001) anterior cerebral artery supply areas. According to the ASPECTS model, the right M3 (OR 8.52, 95% CI 1.41-51.34, p = 0.013) and right A2 (OR 7.84, 95% CI 1.97-31.15, p = 0.003) regions were independently associated with unfavorable outcome.

DISCUSSION

DCI-related infarction was associated with a 5-fold increase in the odds of unfavorable outcome, after 1 year. Ischemic lesions in specific anatomical regions are more likely to contribute to unfavorable outcome.

TRIAL REGISTRATION INFORMATION

Data collection in Aachen was registered in the German Clinical Trial Register (DRKS00030505); on January 3, 2023.

Dynamically Normalized Pupillometry for Detecting Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

OBJECTIVES

Delayed cerebral ischemia (DCI) is a major driver of morbidity after aneurysmal subarachnoid hemorrhage (aSAH). Quantitative pupillometry has been shown to be of prognostic value after acute neurological injury. However, the evidence for the use of pupillometric features for the detection of DCI has been conflicting. The aim of this study was to investigate the prognostic value of frequent pupillometric monitoring for DCI detection.

DESIGN

Observational cohort study from a prospective aSAH registry.

SETTING

Tertiary referral center.

PATIENTS

Adult patients with confirmed aSAH admitted to the ICU between March 2019 and December 2023.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred fourteen patients were included, of which 31 (27.2%) suffered from DCI. All patients underwent frequent pupillometry (every 3 hr). We determined the absolute value of the neurological pupil index (NPi) and constriction velocity (CV), and their value normalized to the maximal recorded value between the admission and the pupillometry measure to account for personalized baselines. The association between pupillometry values and the occurrence of DCI within 6-24 hours was investigated. Normalized CV had the best discriminative performance to identify DCI within 8 hours, with an area under the receiver operating characteristic curve of 0.82 (95% CI, 0.69-0.91). NPi, as well as non-normalized metrics, were not significantly associated with DCI.

CONCLUSIONS

Normalized CV has a clinically and statistically significant association with the occurrence of DCI after aSAH. Frequent quantitative pupillometry could improve the multimodal monitoring of patients after aSAH with the goal of improving the identification of patients likely to benefit from therapeutic interventions.

Cerebral Hemodynamics and Levosimendan Use in Patients with Cerebral Vasospasm and Subarachnoid Hemorrhage: An Observational Perfusion CT-Based Imaging Study

BACKGROUND

Delayed cerebral ischemia associated with cerebral vasospasm (CVS) in aneurysmal subarachnoid hemorrhage significantly affects patient prognosis. Levosimendan has emerged as a potential treatment, but clinical data are lacking. The aim of this study is to decipher levosimendan's effect on cerebral hemodynamics by automated quantitative measurements of brain computed tomography perfusion (CTP).

METHODS

We conducted a retrospective analysis of a database of a neurosurgical intensive care unit. All patients admitted from January 2018 to July 2022 for aneurysmal subarachnoid hemorrhage and treated with levosimendan for CVS who did not respond to other therapies were included. Quantitative measurements of time to maximum (Tmax), relative cerebral blood volume (rCBV), and relative cerebral blood flow (rCBF) were automatically compared with coregistered CTP before and after levosimendan administration in oligemic regions.

RESULTS

Of 21 patients included, CTP analysis could be performed in 16. Levosimendan improved Tmax from 14.4 s (interquartile range [IQR] 9.1-21) before treatment to 7.1 s (IQR 5.5-8.1) after treatment (p < 0.001). rCBV (94% [IQR 79-103] before treatment and 89% [IQR 72-103] after treatment, p = 0.63) and rCBF (85% [IQR 77-90] before treatment and 87% [IQR 73-98] after treatment, p = 0.98) remained stable. The subgroup of six patients who did not develop cerebral infarction attributed to delayed cerebral ischemia showed an approximately 10% increase (rCBV 85% [IQR 79-99] before treatment vs. 95% [IQR 88-112] after treatment, p = 0.21; rCBF 81% [IQR 76-87] before treatment vs. 89% [IQR 84-99] after treatment, p = 0.4).

CONCLUSIONS

In refractory CVS, levosimendan use was associated with a significant reduction in Tmax in oligemic regions. However, this value remained at an abnormal level, indicating the presence of a persistent CVS. Further analysis raised the hypothesis that levosimendan causes cerebral vasodilation, but other studies are needed because our design does not allow us to quantify the effect of levosimendan from that of the natural evolution of CVS.

Risk Factors and Clinical Significance of Ultra-Long-Term Microischemia After Intracranial Aneurysm Embolization

INTRODUCTION

This study aimed to explore influencing factors and clinical significance of ultra-long-term microischemia following intracranial aneurysm (IA) embolization and establish a theoretical foundation for reducing both the incidence of ultra-long-term microischemia and cognitive dysfunction in patients post embolization.

METHODS

A retrospective analysis was conducted on data from 147 patients who received endovascular treatment for IAs. Patients were categorized into microischemic and control (non-microischemic) groups on the based on the findings of high-resolution magnetic resonance vessel wall imaging (HR-VWI) examinations performed 3 days postoperatively and 6 months postoperatively. Risk factors for the occurrence of ultra-long-term microischemia were determined by univariate analysis and multivariate logistic regression analysis.

RESULTS

Out of 147 patients included in the study, 51 (34.69%) developed microischemia while the remaining 96 (65.31%) did not experience this condition. Analysis revealed that factors such as sex, age, history of underlying diseases (hypertension, diabetes mellitus), aneurysmal site characteristics, the presence or absence of stenosis in the aneurysm-bearing artery, modified Fisher score at admission, Barthel's index at discharge, immunoinflammatory index at 3 days postoperatively and at the 6-month follow-up, the presence or absence of aneurysmal wall enhancement, and the presence or absence of aneurysmal lumen showed no statistically significant differences between the two groups (all P > 0.05). By contrast, variables like in operative time, rupture status of the aneurysm before surgery according to World Federation of Neurologic Surgeons (WFNS) grade, aneurysm size, number of stents used, number of guidewires and catheters used, and Evans index between the two groups were found to have statistically significant disparities between those who developed microischemia and those who did not (P < 0.05). A subsequent multivariate analysis revealed that aneurysm size, Evans index, and the number of stents used were independent risk factors for the occurrence of ultra-long-term microischemia after surgical intervention of aneurysms (P < 0.05). The receiver operating characteristic (ROC) curves of the patients were constructed on the basis of risk factors determined through multivariate logistic regression analysis. Results indicated that aneurysm size (area under ROC curve (AUC) 0.619, sensitivity 94.7%, specificity 17.1%, P = 0.049), Evans index (AUC 0.670, sensitivity 96.4%, specificity 26.8%, P = 0.004), and number of stents (AUC 0.639, sensitivity 44.6%, specificity 90.2%, P < 0.001) effectively predicted the occurrence of microischemia. The incidence of cognitive dysfunction was higher in the microischemic group than in the control group (P < 0.05), and a greater number of microischemic foci was associated with a higher incidence of cognitive dysfunction. The proportion of microschemia foci in the thalamus and basal ganglia in patients with cognitive dysfunction (60.87%) was significantly higher than that in patients without cognitive dysfunction (34.55%) (P < 0.05).

CONCLUSION

Aneurysm size, Evans index > 0.3, and the quantity of stents were independent risk factors for the occurrence of ultra-long-term microischemia after aneurysm embolization and provided good predictive performance. Cognitive dysfunction was closely associated with microischemia, with its severity increasing with an increase in the number of ischemic foci.

Application of transcranial transmission ultrasound in the detection of vasospasm in patients with aneurysmal subarachnoid hemorrhage: illustrative cases

BACKGROUND

Effective management of patients with aneurysmal subarachnoid hemorrhage (aSAH) demands vigilant monitoring and treatment, given the risks of complications such as cerebral vasospasm and delayed ischemic neurological deficits (DINDs). Transcranial transmission ultrasound (TTUS) is a well-established technique for assessing brain pulsatility. This pilot study aims to explore the utility of TTUS in detecting impaired intracerebral blood flow associated with DINDs.

OBSERVATIONS

The authors examined 2 male patients, ages 45 and 52 years, with aSAH Hunt and Hess grades 4 and 2, respectively, who developed DINDs during their clinical course. Simultaneous recordings of arterial blood pressure, heart rate, and TTUS measurements were obtained in the intensive care unit. TTUS analysis revealed abnormal arrhythmic wave patterns during DIND episodes, whereas baseline measurements on DIND-free days showed no abnormalities. Following endovascular spasmolysis, TTUS demonstrated a normalization of abnormal waves, returning to baseline levels, alongside the resolution of neurological symptoms.

LESSONS

TTUS, a noninvasive method for assessing brain pulsatility, shows promise as a novel tool for monitoring aSAH patients, potentially aiding in prompt diagnostics and additional therapeutic interventions. Its capacity to provide further insights for individuals at risk of delayed cerebral ischemia warrants further investigation in clinical studies. https://thejns.org/doi/10.3171/CASE24146.

Predicting postacute phase anaemia after aneurysmal subarachnoid haemorrhage: nomogram development and validation

BACKGROUND

Anaemia is a severe and common complication in patients with aneurysmal subarachnoid haemorrhage (aSAH). Early intervention for at-risk patients before anaemia occurs is indicated as potentially beneficial, but no validated method synthesises patients' complicated clinical features into an instrument. The purpose of the current study was to develop and externally validate a nomogram that predicted postacute phase anaemia after aSAH.

METHODS

We developed a novel nomogram for aSAH patients to predict postacute phase anaemia (3 days after occurrence of aSAH, prior to discharge) on the basis of demographic information, imaging, type of treatment, aneurysm features, blood tests and clinical characteristics. We designed the model from a development cohort and tested the nomogram in external and prospective validation cohorts. We included 456 aSAH patients from The First Affiliated Hospital for the development, 220 from Sanmen People's Hospital for external validation and a prospective validation cohort that included 13 patients from Hangzhou Red Cross Hospital. We assessed the performance of the nomogram via concordance statistics and evaluated the calibration of predicted anaemia outcome with observed anaemia occurrence.

RESULTS

Variables included in the nomogram were age, treatment method (open surgery or endovascular therapy), baseline haemoglobin level, fasting blood glucose level, systemic inflammatory response syndrome score on admission, Glasgow Coma Scale score, aneurysm size, prothrombin time and heart rate. In the validation cohort, the model for prediction of postacute phase anaemia had a c-statistic of 0.910, with satisfactory calibration (judged by eye) for the predicted and reported anaemia outcome. Among forward-looking forecasts, our predictive model achieved an 84% success rate, which showed that it has some clinical practicability.

CONCLUSIONS

The developed and validated nomogram can be used to calculate individualised anaemia risk and has the potential to serve as a practical tool for clinicians in devising improved treatment strategies for aSAH.

Immuno-MRI for Stroke Diagnosis and Prognosis

Following a stroke, an inflammatory response occurs, characterized by an increased blood-brain barrier permeability, expression of endothelial trafficking molecules, and infiltration of immune cells. Adhesion molecules expressed on activated brain endothelial cells are potential biomarkers of intraparenchymal inflammation. However, in current clinical practice, it is not possible to measure endothelial activation using clinically available imaging. Using targeted micro-sized particles of iron oxide (MPIO), immuno-MRI enables the detection of endothelial adhesion molecules at high resolution and, consequently, facilitates the detection of stroke-induced brain inflammation. In this review, we highlight the most recent studies that used immuno-MRI in models of neurovascular disorders, including transient ischemic attack, ischemic stroke, intracranial hemorrhage, and subarachnoid hemorrhage. We also discuss the potential of immuno-MRI in clinical practice and the necessary next steps for its implementation in patients.

Cerebrospinal fluid volume as an early radiological factor for clinical course prediction after aneurysmal subarachnoid hemorrhage. A pilot study

BACKGROUND

The pathological mechanisms following aneurysmal subarachnoid hemorrhage (SAH) are poorly understood. Limited clinical evidence exists on the association between cerebrospinal fluid (CSF) volume and the risk of delayed cerebral ischemia (DCI) or cerebral vasospasm (CV). In this study, we raised the hypothesis that the amount of CSF or its ratio to hemorrhage blood volume, as determined from non-contrast Computed Tomography (NCCT) images taken on admission, could be a significant predictor for CV and DCI.

METHODS

The pilot study included a retrospective analysis of NCCT scans of 49 SAH patients taken shortly after an aneurysm rupture (33 males, 16 females, mean age 56.4 ± 15 years). The SynthStrip and Slicer3D software tools were used to extract radiological factors - CSF, brain, and hemorrhage volumes from the NCCT images. The "pure" CSF volume (VCSF) was estimated in the range of [-15, 15] Hounsfield units (HU).

RESULTS

VCSF was negatively associated with the risk of CV occurrence (p = 0.0049) and DCI (p = 0.0069), but was not associated with patients' outcomes. The hemorrhage volume (VSAH) was positively associated with an unfavorable outcome (p = 0.0032) but was not associated with CV/DCI. The ratio VSAH/VCSF was positively associated with, both, DCI (p = 0.031) and unfavorable outcome (p = 0.002). The CSF volume normalized by the brain volume showed the highest characteristics for DCI prediction (AUC = 0.791, sensitivity = 0.80, specificity = 0.812) and CV prediction (AUC = 0.769, sensitivity = 0.812, specificity = 0.70).

CONCLUSION

It was demonstrated that "pure" CSF volume retrieved from the initial NCCT images of SAH patients (including CV, Non-CV, DCI, Non-DCI groups) is a more significant predictor of DCI and CV compared to other routinely used radiological biomarkers. VCSF could be used to predict clinical course as well as to personalize the management of SAH patients. Larger multicenter clinical trials should be performed to test the added value of the proposed methodology.

Predictive value of cerebrovascular time constant for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Time constant of the cerebral arterial bed (τ) is a transcranial Doppler (TCD) based metric that is expected to quantify the transit time of red blood cells from the insonation point to the arteriole-capillary boundary during a cardiac cycle. This study aims to assess the potential of τ as an early predictor of delayed cerebral ischemia (DCI). Consecutive patients (56 ± 15 years) treated for aneurysmal subarachnoid haemorrhage were included in the study. τ was assessed through a modelling approach that involved simultaneous recordings of arterial blood pressure and cerebral blood flow velocity (CBFV) from TCD's first recordings. 71 patients were included. 17 patients experienced DCI. τ was significantly shorter in patients who later developed DCI: 187 ± 64 ms vs. 249 ± 184 ms; p = 0.040 with moderate effect size (rG = 0.24). Logistic regression showed that there was a significant association between increased CBFV, shortened τ, and the development of DCI (χ2 = 11.54; p = 0.003) with AUC for the model 0.75. Patients who had both shortened τ and increased CBFV were 20 times more likely to develop DCI (OR = 20.4 (2.2-187.7)). Our results suggest that early alterations in τ are associated with DCI after aSAH. The highest performance of the model including both CBFV and τ may suggest the importance of both macrovascular and microvascular changes assessment.

Diagnostic value of transcranial doppler to predict delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage : To predict delayed cerebral ischemia

BACKGROUND

Transcranial Doppler (TCD) is a technique to assess blood flow velocity in the cerebral arteries. TCD is frequently used to monitor aneurysmal subarachnoid hemorrhage (aSAH) patients. This study compares TCD-criteria for vasospasm and its association with Delayed Cerebral Ischemia (DCI). An overall score based on flow velocities of various intracranial arteries was developed and evaluated.

METHODS

A retrospective diagnostic accuracy study was conducted between 1998 and 2017 with 621 patients included. Mean flow velocity (MFV) of the cerebral artery was measured between 2-5 days and between 6-9 days after ictus. Cutoff values from the literature, new cutoff values, and a new composite score (Combined Severity Score) were used to predict DCI. Sensitivity, specificity, and area under the curve (AUC) were determined, and logistic regression analysis was performed.

RESULTS

The Combined Severity Score showed an AUC 0.64 (95%CI 0.56-.71) at days 2-5, with sensitivity 0.53 and specificity 0.74. The Combined Severity Score had an adjusted Odds Ratio of 3.41 (95CI 1.86-6.32) for DCI. MCA-measurements yielded the highest AUC to detect DCI at day 2-5: AUC 0.65 (95%CI 0.58-0.73). Optimal cutoff MFV of 83 cm/s for MCA resulted in sensitivity 0.73 and specificity 0.50 at days 2-5.

CONCLUSION

TCD-monitoring of aSAH patients may be a valuable strategy for DCI risk stratification. Lower cutoff values can be used in the early phase after the ictus (day 2-5) than are commonly used now. The Combined Severity Score incorporating all major cerebral arteries may provide a meaningful contribution to interpreting TCD measurements.

Evolving frontiers: endovascular strategies for the treatment of delayed cerebral ischemia

Cerebral vasospasm and delayed cerebral ischemia represent a very challenging aspect of cerebrovascular pathophysiology, most commonly subarachnoid hemorrhage, with significantly high mortality if left untreated. Considerable advances have been made in medical treatment and prompt diagnosis, while newer endovascular modalities have recently been proposed for cases of resistant cerebral vasospasm. However, there is still paucity of data regarding which and whether a single endovascular technique is non inferior to the pharmacological standard of care. In this review, we aim to summarize the current funds of knowledge concerning cerebral vasospasm and the emerging role of the endovascular techniques for its treatment.

Early Hydrogen-Oxygen Gas Mixture Inhalation in Patients with Aneurysmal Subarachnoid Hemorrhage (HOMA): study protocol for a randomized controlled trial

BACKGROUND

Aneurysmal subarachnoid hemorrhage (aSAH) is a life-threatening neurosurgical emergency with a high mortality rate. Delayed cerebral ischemia (DCI) and cerebral vasospasm (CVS) are delayed products of early brain injury (EBI), which may constitute the principal determinant of an unfavorable patient prognosis. Consequently, the mitigation of DCI and CVS assumes paramount significance in the pursuit of enhanced patient outcomes. However, except for oral nimodipine, there is no effective therapy available in the current guideline. Hence, the exigency arises to proffer novel treatment paradigms. The diversity of hydrogen therapeutic targets has been largely reported in basic research, unveiling its latent capacity to ameliorate EBI in aSAH patients.

METHODS

Early Hydrogen-Oxygen Gas Mixture Inhalation in Patients with Aneurysmal Subarachnoid Hemorrhage (HOMA), a single-center, prospective, open-labeled, randomized controlled clinical trial, endeavors to evaluate the efficacy and safety of hydrogen-oxygen gas mixture inhalation therapy in aSAH patients. A cohort of 206 patients will be randomized to either hydrogen-oxygen gas mixture inhalation group (8 h per day, 3 L/min, hydrogen concentration of 67%, oxygen concentration of 33%) or oxygen inhalation group (8 h per day, 3 L/min, oxygen concentration of 33%) within 72 h after aSAH and treated for 7 days in the ICU ward. The primary outcomes are the incidence of DCI and CVS during hospitalization.

DISCUSSION

The HOMA aims to evaluate the effectiveness of hydrogen-oxygen gas mixture inhalation therapy in preventing DCI or CVS and improving outcomes in aSAH patients. Notably, this is the first large-scale trial of hydrogen therapy in aSAH patients. Given that the Chinese population represents a significant portion of the global population and the increasing incidence of stroke due to aging, optimizing patient care is vital. Given the current challenges in aSAH patient outcomes, initiating more prospective clinical trials is essential. Recent research has shown hydrogen's therapeutic potential, aligning with EBI in aSAH, driving our exploration of hydrogen therapy's mechanisms in post-aneurysm rupture damage.

ETHICS AND DISSEMINATION

The protocol for the HOMA study was approved by the Ethics Committee of Beijing Tiantan Hospital, Capital Medical University (KY 2022-020-02). All results of the present study will be published in peer-reviewed journals and presented at relevant conferences.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05282836. Registered on March 16, 2022.

Role of microglia after subarachnoid hemorrhage

Subarachnoid hemorrhage is a devastating sequela of aneurysm rupture. Because it disproportionately affects younger patients, the population impact of hemorrhagic stroke from subarachnoid hemorrhage is substantial. Secondary brain injury is a significant contributor to morbidity after subarachnoid hemorrhage. Initial hemorrhage causes intracranial pressure elevations, disrupted cerebral perfusion pressure, global ischemia, and systemic dysfunction. These initial events are followed by two characterized timespans of secondary brain injury: the early brain injury period and the delayed cerebral ischemia period. The identification of varying microglial phenotypes across phases of secondary brain injury paired with the functions of microglia during each phase provides a basis for microglia serving a critical role in both promoting and attenuating subarachnoid hemorrhage-induced morbidity. The duality of microglial effects on outcomes following SAH is highlighted by the pleiotropic features of these cells. Here, we provide an overview of the key role of microglia in subarachnoid hemorrhage-induced secondary brain injury as both cytotoxic and restorative effectors. We first describe the ontogeny of microglial populations that respond to subarachnoid hemorrhage. We then correlate the phenotypic development of secondary brain injury after subarachnoid hemorrhage to microglial functions, synthesizing experimental data in this area.

Modulation of the Immunological Milieu in Acute Aneurysmal Subarachnoid Hemorrhage: The Potential Role of Monocytes Through CXCL10 Secretion

Emerging evidence indicates that aneurysmal subarachnoid hemorrhage (aSAH) elicits a response from both innate and adaptive immune systems. An upregulation of CD8 + CD161 + cells has been observed in the cerebrospinal fluid (CSF) after aSAH, yet the precise role of these cells in the context of aSAH is unkown. CSF samples from patients with aSAH and non-aneurysmal SAH (naSAH) were analyzed. Single-cell RNA sequencing (scRNAseq) was performed on CD8 + CD161 + sorted samples from aSAH patients. Cell populations were identified using "clustering." Gene expression levels of ten previously described genes involved in inflammation were quantified from aSAH and naSAH samples using RT-qPCR. The study focused on the following genes: CCL5, CCL7, APOE, SPP1, CXCL8, CXCL10, HMOX1, LTB, MAL, and HLA-DRB1. Gene clustering analysis revealed that monocytes, NK cells, and T cells expressed CD8 + CD161 + in the CSF of patients with aSAH. In comparison to naSAH samples, aSAH samples exhibited higher mRNA levels of CXCL10 (median, IQR = 90, 16-149 vs. 0.5, 0-6.75, p = 0.02). A trend towards higher HMOX1 levels was also observed in aSAH (median, IQR = 12.6, 9-17.6 vs. 2.55, 1.68-5.7, p = 0.076). Specifically, CXCL10 and HMOX1 were expressed by the monocyte subpopulation. Monocytes, NK cells, and T cells can potentially express CD8 + CD161 + in patients with aSAH. Notably, monocytes show high levels of CXCL10. The elevated expression of CXCL10 in aSAH compared to naSAH indicates its potential significance as a target for future studies.

Early localization of tissue at risk for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage: blood distribution on initial imaging vs early CT perfusion

OBJECTIVE

Delayed cerebral ischemia (DCI) is a potentially reversible adverse event after aneurysmal subarachnoid hemorrhage (aSAH), when early detected and treated. Computer tomography perfusion (CTP) is used to identify the tissue at risk for DCI. In this study, the predictive power of early CTP was compared with that of blood distribution on initial CT for localization of tissue at risk for DCI.

METHODS

A consecutive patient cohort with aSAH treated between 2012 and 2020 was retrospectively analyzed. Blood distribution on CT was semi-quantitatively assessed with the Hijdra-score. The vessel territory with the most surrounding blood and the one with perfusion deficits on CTP performed on day 3 after ictus were considered to be at risk for DCI, respectively.

RESULTS

A total of 324 patients were included. Delayed infarction occurred in 17% (56/324) of patients. Early perfusion deficits were detected in 82% (46/56) of patients, 85% (39/46) of them developed infarction within the predicted vessel territory at risk. In 46% (25/56) a vessel territory at risk was reliably determined by the blood distribution. For the prediction of DCI, blood amount/distribution was inferior to CTP. Concerning the identification of "tissue at risk" for DCI, a combination of both methods resulted in an increase of sensitivity to 64%, positive predictive value to 58%, and negative predictive value to 92%.

CONCLUSIONS

Regarding the DCI-prediction, early CTP was superior to blood amount/distribution, while a consideration of subarachnoid blood distribution may help identify the vessel territories at risk for DCI in patients without early perfusion deficits.

Therapeutic Potential of Natural Compounds in Subarachnoid Haemorrhage

Subarachnoid hemorrhage (SAH) is a common and fatal cerebrovascular disease with high morbidity, mortality and very poor prognosis worldwide. SAH can induce a complex series of pathophysiological processes, and the main factors affecting its prognosis are early brain injury (EBI) and delayed cerebral ischemia (DCI). The pathophysiological features of EBI mainly include intense neuroinflammation, oxidative stress, neuronal cell death, mitochondrial dysfunction and brain edema, while DCI is characterized by delayed onset ischemic neurological deficits and cerebral vasospasm (CVS). Despite much exploration in people to improve the prognostic outcome of SAH, effective treatment strategies are still lacking. In recent years, numerous studies have shown that natural compounds of plant origin have unique neuro- and vascular protective effects in EBI and DCI after SAH and long-term neurological deficits, which mainly include inhibition of inflammatory response, reduction of oxidative stress, anti-apoptosis, and improvement of blood-brain barrier and cerebral vasospasm. The aim of this paper is to systematically explore the processes of neuroinflammation, oxidative stress, and apoptosis in SAH, and to summarize natural compounds as potential targets for improving the prognosis of SAH and their related mechanisms of action for future therapies.

Sex-Related Differences in Mortality, Delayed Cerebral Ischemia, and Functional Outcomes in Patients with Aneurysmal Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis

Background/Objective: Sex-related differences among patients with aneurysmal subarachnoid hemorrhage (aSAH) and their potential clinical implications have been insufficiently investigated. To address this knowledge gap, we conduct a comprehensive systematic review and meta-analysis. Methods: Sex-specific differences in patients with aSAH, including mortality, delayed cerebral ischemia (DCI), and functional outcomes were assessed. The functional outcome was dichotomized into favorable or unfavorable based on the modified Rankin Scale (mRS), Glasgow Outcome Scale (GOS), and Glasgow Outcome Scale Extended (GOSE). Results: Overall, 2823 studies were identified in EMBASE, MEDLINE, PubMed, and by manual search on 14 February 2024. After an initial assessment, 74 studies were included in the meta-analysis. In the analysis of mortality, including 18,534 aSAH patients, no statistically significant differences could be detected (risk ratio (RR) 0.99; 95% CI, 0.90-1.09; p = 0.91). In contrast, the risk analysis for DCI, including 23,864 aSAH patients, showed an 11% relative risk reduction in DCI in males versus females (RR, 0.89; 95% CI, 0.81-0.97; p = 0.01). The functional outcome analysis (favorable vs. unfavorable), including 7739 aSAH patients, showed a tendency towards better functional outcomes in men than women; however, this did not reach statistical significance (RR, 1.02; 95% CI, 0.98-1.07; p = 0.34). Conclusions: In conclusion, the available data suggest that sex/gender may play a significant role in the risk of DCI in patients with aSAH, emphasizing the need for sex-specific management strategies.

Sodium and Its Impact on Outcome After Aneurysmal Subarachnoid Hemorrhage in Patients With and Without Delayed Cerebral Ischemia

OBJECTIVES

To perform a detailed examination of sodium levels, hyponatremia and sodium fluctuations, and their association with delayed cerebral ischemia (DCI) and poor outcome after aneurysmal subarachnoid hemorrhage (aSAH).

DESIGN

An observational cohort study from a prospective SAH Registry.

SETTING

Tertiary referral center focused on SAH treatment in the Amsterdam metropolitan area.

PATIENTS

A total of 964 adult patients with confirmed aSAH were included between 2011 and 2021.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 277 (29%) developed DCI. Hyponatremia occurred significantly more often in DCI patients compared with no-DCI patients (77% vs. 48%). Sodium levels, hyponatremia, hypernatremia, and sodium fluctuations did not predict DCI. However, higher sodium levels were significantly associated with poor outcome in DCI patients (DCI onset -7, DCI +0, +1, +2, +4, +5, +8, +9 d), and in no-DCI patients (postbleed day 6-10 and 12-14). Also, hypernatremia and greater sodium fluctuations were significantly associated with poor outcome in both DCI and no-DCI patients.

CONCLUSIONS

Sodium levels, hyponatremia, and sodium fluctuations were not associated with the occurrence of DCI. However, higher sodium levels, hypernatremia, and greater sodium fluctuations were associated with poor outcome after aSAH irrespective of the presence of DCI. Therefore, sodium levels, even with mild changes in levels, warrant close attention.

Blood DNA Methylation Analysis Reveals a Distinctive Epigenetic Signature of Vasospasm in Aneurysmal Subarachnoid Hemorrhage

Vasospasm is a potentially preventable cause of poor prognosis in patients with aneurysmal subarachnoid hemorrhage (aSAH). Epigenetics might provide insight on its molecular mechanisms. We aimed to analyze the association between differential DNA methylation (DNAm) and development of vasospasm. We conducted an epigenome-wide association study in 282 patients with aSAH admitted to our hospital. DNAm was assessed with the EPIC Illumina chip (> 850 K CpG sites) in whole-blood samples collected at hospital admission. We identified differentially methylated positions (DMPs) at the CpG level using Cox regression models adjusted for potential confounders, and then we used the DMP results to find differentially methylated regions (DMRs) and enriched biological pathways. A total of 145 patients (51%) experienced vasospasm. In the DMP analysis, we identified 31 CpGs associated with vasospasm at p-value < 10-5. One of them (cg26189827) was significant at the genome-wide level (p-value < 10-8), being hypermethylated in patients with vasospasm and annotated to SUGCT gene, mainly expressed in arteries. Region analysis revealed 13 DMRs, some of them annotated to interesting genes such as POU5F1, HLA-DPA1, RUFY1, and CYP1A1. Functional enrichment analysis showed the involvement of biological processes related to immunity, inflammatory response, oxidative stress, endothelial nitric oxide, and apoptosis. Our findings show, for the first time, a distinctive epigenetic signature of vasospasm in aSAH, establishing novel links with essential biological pathways, including inflammation, immune responses, and oxidative stress. Although further validation is required, our results provide a foundation for future research into the complex pathophysiology of vasospasm.

Could Phosphorous MR Spectroscopy Help Predict the Severity of Vasospasm? A Pilot Study

One of the main causes of the dismal prognosis in patients who survive the initial bleeding after aneurysmal subarachnoidal hemorrhage is the delayed cerebral ischaemia caused by vasospasm. Studies suggest that cerebral magnesium and pH may potentially play a role in the pathophysiology of this adverse event. Using phosphorous magnetic resonance spectrocopy (31P-MRS), we calculated the cerebral magnesium (Mg) and pH levels in 13 patients who suffered from aSAH. The values between the group that developed clinically significant vasospasm (n = 7) and the group that did not (n = 6) were compared. The results of this study show significantly lower cerebral Mg levels (p = 0.019) and higher pH levels (p < 0.001) in the cumulative group (all brain voxels together) in patients who developed clinically significant vasospasm. Further clinical studies on a larger group of carefully selected patients are needed in order to predict clinically significant vasospasm.