Dose-Dependent Inhibitory Effects of Cilostazol on Delayed Cerebral Infarction After Aneurysmal Subarachnoid Hemorrhage

Prognosis of patients with aneurysmal subarachnoid hemorrhage treated with fasudil hydrochloride-cilostazol combination therapy: A cross-sectional analysis of a nationwide inpatient database, 2016 to 2020

Fasudil hydrochloride is used as a therapeutic agent for cerebral vasospasm after aneurysmal subarachnoid hemorrhage surgery; however, its limited efficacy necessitates additional treatment options. Although the therapeutic potential of cilostazol for improved outcomes after aneurysmal subarachnoid hemorrhage has been reported, no clinical studies have examined the effects of administering both cilostazol and fasudil hydrochloride on mortality and physical disability in patients. Therefore, we investigated the impact of combined fasudil hydrochloride and cilostazol administration among patients with subarachnoid hemorrhage (SAH) in Japan. A cross-sectional study was conducted using the diagnosis procedure combination database among patients with SAH who received fasudil hydrocholoride alone (n = 8728) or in combination with cilostazol (n = 8052) between April 2016 and March 2020. The primary endpoint was in-hospital mortality, and the secondary endpoint was the proportion of patients with a modified Rankin Scale (mRS) score ≤2 at discharge. Statistical analysis was performed using multivariate-adjusted logistic regression analysis with a significance level of 5%. The mean age was 63.8 years (standard deviation [SD]: 14.4) in the fasudil hydrochloride monotherapy group (F group) and 62.8 years (SD: 14.3) in the fasudil hydrochloride and cilostazol combination group (FC group). Female patients accounted for 69.5% in the F group and 70.1% in the FC group. The in-hospital mortality rate was 7.4% in the F group and 4.0% in the FC group. Patients in the FC group had a lower in-hospital mortality rate than did those in the F group (odds ratio 0.28, 95% confidence interval [CI] 0.23-0.34, P < .001). The proportion of patients with an mRS score ≤2 at discharge was 49.4% in the F group and 55.7% in the FC group. Patients in the FC group had a higher mRS score ≤2 at discharge than those in the F group (odds ratio 1.43, 95% CI: 1.31-1.55, P < .001). We investigated the impact of combined fasudil hydrochloride and cilostazol administration on the prognosis of Japanese patients with SAH. The results suggest that combination therapy with fasudil hydrochloride and cilostazol may have a synergistic effectiveness on improving SAH prognosis compared with fasudil hydrochloride monotherapy. In future, research is needed to understand the mechanisms underlying the combined use of cilostazol.

Therapeutic potential of stem cells in subarachnoid hemorrhage

Aneurysm rupture can result in subarachnoid hemorrhage, a condition with potentially severe consequences, such as disability and death. In the acute stage, early brain injury manifests as intracranial pressure elevation, global cerebral ischemia, acute hydrocephalus, and direct blood-brain contact due to aneurysm rupture. This may subsequently cause delayed cerebral infarction, often with cerebral vasospasm, significantly affecting patient outcomes. Chronic complications such as brain volume loss and chronic hydrocephalus can further impact outcomes. Investigating the mechanisms of subarachnoid hemorrhage-induced brain injury is paramount for identifying effective treatments. Stem cell therapy, with its multipotent differentiation capacity and anti-inflammatory effects, has emerged as a promising approach for treating previously deemed incurable conditions. This review focuses on the potential application of stem cells in subarachnoid hemorrhage pathology and explores their role in neurogenesis and as a therapeutic intervention in preclinical and clinical subarachnoid hemorrhage studies.

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.

Cilostazol Alleviates Delayed Cerebral Ischemia After Subarachnoid Hemorrhage by Attenuating Microcirculatory Dysfunction

Cilostazol, a phosphodiesterase 3 (PDE3) inhibitor that exerts antiplatelet effects, has therapeutic potential for delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). However, its mechanism of action remains unclear. We hypothesized that cilostazol alleviates DCI by improving cerebral microcirculatory dysfunction, which is a component of early brain injury. To test this hypothesis, we analyzed the intracerebral circulation time (iCCT) in 256 patients with aSAH from two randomized controlled trials (74 received cilostazol, 54 received pitavastatin, and 128 were controls). A minority of patients (n = 72, 28%) developed severe angiographic vasospasm (aVS) and DCI (n = 42, 16%) and had poor outcomes (n = 35, 14%). We measured iCCT as the time to peak in the ultraearly phase (baseline) and the subacute phase or at DCI onset (follow-up). The cilostazol group had shorter follow-up iCCT and larger iCCT differences than the other groups, indicating improved microcirculatory function, particularly in patients with DCI and poor outcomes. Multivariate analysis revealed that cilostazol treatment is a significant predictor of favorable outcomes, whereas DCI occurrence, a decrease in iCCT differences, and high clinical severity (Hunt & Hess grades 3-4) were associated with poor outcomes. Diminished microcirculatory dysfunction may alleviate DCI and improve outcomes among patients with aSAH following cilostazol treatment. Further research is warranted to confirm these findings and explore the dose-dependent effects of cilostazol on the microcirculatory function.

Recent advancement of novel marine fungi derived secondary metabolite fibrinolytic compound FGFC in biomedical applications: a review

For several decades, products derived from marine natural sources (PMN) have been widely identified for several therapeutic applications due to their rich sources of bioactive sub-stances, unique chemical diversity, biocompatibility and excellent biological activity. For the past 15 years, our research team explored several PMNs, especially fungi fibrinolytic compounds (FGFCs). FGFC is an isoindolone alkaloid derived from marine fungi, also known as staplabin analogs or Stachybotrys microspora triprenyl phenol (SMTP). For instance, our previous studies explored different types of FGFCs such as FGFC 1, 2, 3 and 4 from the marine fungi Stachybotrys longispora FG216 derived metabolites. The derivatives of FGFC are potentially employed in several disease treatments, mainly for stroke, cancer, ischemia, acute kidney injury, inflammation, cerebral infarction, thrombolysis and hemorrhagic activities, etc. Due to the increasing use of FGFCs in pharmaceutical and biomedical applications, it is important to understand the fundamental signaling concept of FGFCs. Hence, for the first time, this review collectively summarizes the background, types, mode of action and biological applications of FGFCs and their current endeavors for future therapies.

Treatment factors to suppress delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage based on VASOGRADE: multicenter cohort study

Delayed cerebral ischemia (DCI) is one of the most important outcome determinants for aneurysmal subarachnoid hemorrhage (aSAH). VASOGRADE, which combines World Federation of Neurological Surgeons grade and modified Fisher grade, is a useful scale for predicting DCI after aSAH. However, no studies have investigated whether VASOGRADE influences the treatment options. We retrospectively analyzed 781 aSAH patients who were prospectively enrolled in 9 primary stroke centers from 2013 to 2021. The total cohort consisted of 76 patients (9.7%) with VASOGRADE-Green, 390 patients (49.9%) with VASOGRADE-Yellow, and 315 patients (40.3%) with VASOGRADE-Red. Worse VASOGRADE had higher incidences of DCI, which occurred in 190 patients (24.3%). As only 5 patients (6.6%) with VASOGRADE-Green developed DCI, we searched for DCI-associated factors in patients with VASOGRADEs-Yellow and -Red. Multivariate analyses revealed independent treatment factors suppressing DCI as follows: no postoperative hemorrhagic complication, combined administration of fasudil hydrochloride and cilostazol, combination of clipping and cisternal drainage, and coiling for VASOGRADE-Yellow; and clipping, and administration of fasudil hydrochloride with or without cilostazol for VASOGRADE-Red. The findings suggest that treatment strategies should be determined based on VASOGRADE to prevent DCI after aSAH.

Advanced Diffusion Tensor Imaging in White Matter Injury After Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is recognized as an especially severe stroke variant, notorious for its high mortality and long-term disability rates, in addition to a range of both immediate and enduring neurologic impacts. Over half of the SAH survivors experience varying degrees of neurologic disorders, with many enduring chronic neuropsychiatric conditions. Due to the limitations of traditional imaging techniques in depicting subtle changes within brain tissues posthemorrhage, the accurate detection and diagnosis of white matter (WM) injuries are complicated. Against this backdrop, diffusion tensor imaging (DTI) has emerged as a promising biomarker for structural imaging, renowned for its enhanced sensitivity in identifying axonal damage. This capability positions DTI as an invaluable tool for forming precise and expedient prognoses for SAH survivors. This study synthesizes an assessment of DTI for the diagnosis and prognosis of neurologic dysfunctions in patients with SAH, emphasizing the notable changes observed in DTI metrics and their association with potential pathophysiological processes. Despite challenges associated with scanning technology differences and data processing, DTI demonstrates significant clinical potential for early diagnosis of cognitive impairments following SAH and monitoring therapeutic effects. Future research requires the development of highly standardized imaging paradigms to enhance diagnostic accuracy and devise targeted therapeutic strategies for SAH patients. In sum, DTI technology not only augments our understanding of the impact of SAH but also may offer new avenues for improving patient prognoses.

Phosphodiesterase in heart and vessels: from physiology to diseases

Phosphodiesterases (PDEs) are a superfamily of enzymes that hydrolyze cyclic nucleotides, including cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Both cyclic nucleotides are critical secondary messengers in the neurohormonal regulation in the cardiovascular system. PDEs precisely control spatiotemporal subcellular distribution of cyclic nucleotides in a cell- and tissue-specific manner, playing critical roles in physiological responses to hormone stimulation in the heart and vessels. Dysregulation of PDEs has been linked to the development of several cardiovascular diseases, such as hypertension, aneurysm, atherosclerosis, arrhythmia, and heart failure. Targeting these enzymes has been proven effective in treating cardiovascular diseases and is an attractive and promising strategy for the development of new drugs. In this review, we discuss the current understanding of the complex regulation of PDE isoforms in cardiovascular function, highlighting the divergent and even opposing roles of PDE isoforms in different pathogenesis.

Cilostazol May Improve Outcomes Even in Patients with Aneurysmal Subarachnoid Hemorrhage Aged 75 Years and Older: Multicenter Cohort Study and Propensity Score-Matched Analyses

BACKGROUND

The opportunities to treat elderly patients with aneurysmal subarachnoid hemorrhage (aSAH) are increasing globally, but the outcome remains poor. This study seeks to investigate treatment-related factors that can modify functional outcomes in patients with aSAH aged ≥75 years.

METHODS

A total of 202 patients with aSAH aged ≥75 years prospectively enrolled in 9 primary stroke centers from 2013 to 2021 were retrospectively analyzed. Clinical variables including treatments for hydrocephalus, angiographic vasospasm, and delayed cerebral ischemia were compared between patients with good (modified Rankin Scale [mRS] score 0-2) and poor (mRS score 3-6) outcomes at 90 days from onset, followed by multivariate analyses to find independent outcome determinants. A modifiable treatment-related variable was evaluated after propensity score matching with adjustments for age, sex, pre-onset mRS score, aSAH severity, and treatment modality.

RESULTS

More than half of patients showed World Federation of Neurological Societies grades IV-V on admission. Univariate analyses showed that advanced age, worse pre-onset mRS score, more severe neurologic status on admission, higher modified Fisher grade on admission computed tomography scans, and acute and chronic hydrocephalus were associated with poor outcomes. In contrast, administration of a phosphodiesterase type III inhibitor, cilostazol, was associated with good outcomes in both univariate (P = 0.036) and multivariate analyses (adjusted odds ratio, 0.305; 95% confidence interval, 0.097-0.955; P = 0.042). Propensity score matching analyses showed that patients treated with cilostazol had better outcomes (P = 0.016) with fewer incidences of delayed cerebral infarction (P = 0.008).

CONCLUSIONS

Even in patients with aSAH aged ≥75 years, cilostazol administration may lead to better outcomes by suppressing the development of delayed cerebral infarction.

Effects of New-Generation Antiepileptic Drug Prophylaxis on Delayed Neurovascular Events After Aneurysmal Subarachnoid Hemorrhage

Neuroelectric disruptions such as seizures and cortical spreading depolarization may contribute to the development of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (SAH). However, effects of antiepileptic drug prophylaxis on outcomes remain controversial in SAH. The authors investigated if prophylactic administration of new-generation antiepileptic drugs levetiracetam and perampanel was beneficial against delayed neurovascular events after SAH. This was a retrospective single-center cohort study of 121 consecutive SAH patients including 56 patients of admission World Federation of Neurological Surgeons grades IV - V who underwent aneurysmal obliteration within 72 h post-SAH from 2013 to 2021. Prophylactic antiepileptic drugs differed depending on the study terms: none (2013 - 2015), levetiracetam for patients at high risks of seizures (2016 - 2019), and perampanel for all patients (2020 - 2021). The 3rd term had the lowest occurrence of delayed cerebral microinfarction on diffusion-weighted magnetic resonance imaging, which was related to less development of DCI. Other outcome measures were similar among the 3 terms including incidences of angiographic vasospasm, computed tomography-detectable delayed cerebral infarction, seizures, and 3-month good outcomes (modified Rankin Scale 0 - 2). The present study suggests that prophylactic administration of levetiracetam and perampanel was not associated with worse outcomes and that perampanel may have the potential to reduce DCI by preventing microcirculatory disturbances after SAH. Further studies are warranted to investigate anti-DCI effects of a selective α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor antagonist perampanel in SAH patients in a large-scale prospective study.

Effect of Cilostazol in Animal Models of Cerebral Ischemia and Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis

BACKGROUND

Cilostazol, a phosphodiesterase III inhibitor, appears to be a promising agent for preventing cerebral ischemia in patients with aneurysmal subarachnoid hemorrhage. Here, the authors perform a systematic review and meta-analysis to quantitatively assess the effects of cilostazol on brain structural and functional outcomes in animal models of cerebral ischemia and subarachnoid hemorrhage-induced cerebral vasospasm.

METHODS

By using the PRISMA guidelines, a search of the PubMed, Scopus, and Web of Science was conducted to identify relevant studies. Study quality of each included study for both systematic reviews were scored by using an adapted 15-item checklist from the Collaborative Approach to Meta-Analysis of Animal Data from Experimental Studies. We calculated a standardized mean difference as effect size for each comparison. For each outcome, comparisons were combined by using random-effects modeling to account for heterogeneity, with a restricted maximum likelihood estimate of between-study variance.

RESULTS

A total of 22 (median [Q1, Q3] quality score of 7 [5, 8]) and 6 (median [Q1, Q3] quality score of 6 [6, 6]) studies were identified for cerebral ischemia and subarachnoid hemorrhage-induced cerebral vasospasm, respectively. Cilostazol significantly reduced the infarct volume in cerebral ischemia models with a pooled standardized mean difference estimate of - 0.88 (95% confidence interval [CI] [- 1.07 to - 0.70], p < 0.0001). Cilostazol significantly reduced neurofunctional deficits in cerebral ischemia models with a pooled standardized mean difference estimate of - 0.66 (95% CI [- 1.06 to - 0.28], p < 0.0001). Cilostazol significantly improved the basilar artery diameter in subarachnoid hemorrhage-induced cerebral vasospasm with a pooled standardized mean difference estimate of 2.30 (95% CI [0.94 to 3.67], p = 0.001). Cilostazol also significantly improved the basilar artery cross-section area with a pooled standardized mean estimate of 1.88 (95% CI [0.33 to 3.43], p < 0.05). Overall, there was between-study heterogeneity and asymmetry in the funnel plot observed in all comparisons.

CONCLUSIONS

Published animal data support the overall efficacy of cilostazol in reducing infarct volume and neurofunctional deficits in cerebral ischemia models and cerebral vasospasm in subarachnoid hemorrhage models.

Laboratory biomarkers of delayed cerebral ischemia following subarachnoid hemorrhage: A systematic review

Delayed cerebral ischemia (DCI) substantially contributes to disability and death in subarachnoid hemorrhage (SAH) patients; however, its pathophysiology is incompletely understood and diagnostic and therapeutic strategies are lacking. Biomarkers may help to elucidate the pathophysiology, optimize early diagnosis, or provide treatment targets. We systematically searched PubMed and Embase on October 13, 2021, for studies that evaluated at least one laboratory biomarker in patients with DCI, using the most up-to-date definition of DCI as proposed by a panel of experts in 2010. Quality of studies was assessed using the Newcastle-Ottawa Scale or Cochrane Collaboration’s risk of bias assessment tool. Biomarkers of clinical and radiological DCI were analyzed separately. Results were meta-analyzed if possible, otherwise narratively reviewed. Biomarkers were classified as significant, inconclusive, or nonsignificant. We defined validated biomarkers as those with significant results in meta-analyses, or in at least two studies using similar methodologies within the same time interval after SAH. The search yielded 209 articles with 724 different biomarkers; 166 studies evaluated 646 biomarkers of clinical DCI, of which 141 were significant and 7 were validated biomarkers (haptoglobulin 2-1 and 2-2, ADAMTS13, vWF, NLR, P-selectin, F2-isoprostane); 78 studies evaluated 165 biomarkers of radiological DCI, of which 63 were significant and 1 was a validated biomarker (LPR). Hence, this review provides a selection of seven biomarkers of clinical DCI and one biomarker of radiological DCI as most promising biomarkers of DCI. Future research should focus on determining the exact predictive, diagnostic, and therapeutic potentials of these biomarkers.

Antiplatelet therapy and delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis

OBJECTIVE

Delayed cerebral ischemia (DCI) is a potentially preventable cause of morbidity and mortality after aneurysmal subarachnoid hemorrhage (aSAH). The authors performed a meta-analysis to assess the effect of antiplatelet therapy (APT) on DCI in patients with aSAH.

METHODS

A systematic review of the PubMed and MEDLINE databases was performed. Study inclusion criteria were 1) ≥ 5 aSAH patients; 2) direct comparison between aSAH management with APT and without APT; and 3) reporting of DCI, angiographic, or symptomatic vasospasm rates for patients treated with versus without APT. The primary efficacy outcome was DCI. The outcomes of the APT versus no-APT cohorts were compared. Bias was assessed using the Downs and Black checklist.

RESULTS

The overall cohort comprised 2039 patients from 15 studies. DCI occurred less commonly in the APT compared with the no-APT cohort (pooled = 15.9% vs 28.6%; OR 0.47, p < 0.01). Angiographic (pooled = 51.6% vs 68.7%; OR 0.46, p < 0.01) and symptomatic (pooled = 23.6% vs 37.7%; OR 0.51, p = 0.01) vasospasm rates were lower in the APT cohort. In-hospital mortality (pooled = 1.7% vs 4.1%; OR 0.53, p = 0.01) and functional dependence (pooled = 21.0% vs 35.7%; OR 0.53, p < 0.01) rates were also lower in the APT cohort. Bleeding event rates were comparable between the two cohorts. Subgroup analysis of cilostazol monotherapy compared with no APT demonstrated a lower DCI rate in the cilostazol cohort (pooled = 10.6% vs 28.1%; OR 0.31, p < 0.01). Subgroup analysis of surgically treated aneurysms demonstrated a lower DCI rate for the APT cohort (pooled = 18.4% vs 33.9%; OR 0.43, p = 0.02).

CONCLUSIONS

APT is associated with improved outcomes in aSAH without an increased risk of bleeding events, particularly in patients who underwent surgical aneurysm repair and those treated with cilostazol. Although study heterogeneity is the most significant limitation of the analysis, the findings suggest that APT is worth exploring in patients with aSAH, particularly in a randomized controlled trial setting.

Effects of cilostazol treatment for patients with aneurysmal subarachnoid hemorrhage: A meta-analysis of 14 studies

OBJECTIVE

To perform an updated meta-analysis to comprehensively assess the efficacy and safety of cilostazol in preventing aneurysmal subarachnoid hemorrhage (SAH)-related secondary complications.

METHODS

Electronic databases of PubMed, the Cochrane library, CNKI and Wanfang were searched on August 2021. Pooled odds ratio (OR) and standardized mean difference (SMD) were calculated for dichotomous and continuous outcomes, respectively.

RESULTS

A total of 14 studies [comprising 18,726 aneurysmal SAH patients (6654 in the cilostazol group and 12,072 in the control group)] performed in Japan or China were included. Compared with the control group, cilostazol treatment significantly reduced the median cerebral artery (SMD = -0.49; p < 0.001), improved the therapeutic efficacy (OR = 2.37; p = 0.009), decreased the incidence of symptomatic vasospasm/delayed cerebral ischemia (OR = 0.42; p < 0.001), severe angiographic vasospasm (OR = 0.54; p < 0.001), new cerebral infarction (OR = 0.33; p < 0.001), poor outcomes (OR = 0.86; p = 0.001), mortality (OR = 0.62; p < 0.001) and increased the incidence of no or mild angiographic vasospasm (OR = 1.94; p = 0.004), but did not induce more adverse events (OR = 1.08; p = 0.871). The mechanism of cilostazol treatment was to inhibit the production of tenascin-C (SMD = -1.46; p < 0.001). These results were hardly changed by subgroup analysis.

CONCLUSION

This meta-analysis indicates cilostazol may be an effective and safe drug for aneurysmal SAH patients. However, further trials involving other world populations are required to demonstrate the generalization of treatment effects of cilostazol.

The Role of Tenascin-C in Tissue Injury and Repair After Stroke

Stroke is still one of the most common causes for mortality and morbidity worldwide. Following acute stroke onset, biochemical and cellular changes induce further brain injury such as neuroinflammation, cell death, and blood-brain barrier disruption. Matricellular proteins are non-structural proteins induced by many stimuli and tissue damage including stroke induction, while its levels are generally low in a normal physiological condition in adult tissues. Currently, a matricellular protein tenascin-C (TNC) is considered to be an important inducer to promote neuroinflammatory cascades and the resultant pathology in stroke. TNC is upregulated in cerebral arteries and brain tissues including astrocytes, neurons, and brain capillary endothelial cells following subarachnoid hemorrhage (SAH). TNC may be involved in blood-brain barrier disruption, neuronal apoptosis, and cerebral vasospasm via the activation of mitogen-activated protein kinases and nuclear factor-kappa B following SAH. In addition, post-SAH TNC levels in cerebrospinal fluid predicted the development of delayed cerebral ischemia and angiographic vasospasm in clinical settings. On the other hand, TNC is reported to promote fibrosis and exert repair effects for an experimental aneurysm via macrophages-induced migration and proliferation of smooth muscle cells. The authors review TNC-induced inflammatory signal cascades and the relationships with other matricellular proteins in stroke-related pathology.

Cerebrovascular pathophysiology of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) remains a serious cerebrovascular disease. Even if SAH patients survive the initial insults, delayed cerebral ischemia (DCI) may occur at 4 days or later post-SAH. DCI is characteristics of SAH, and is considered to develop by blood breakdown products and inflammatory reactions, or secondary to early brain injury, acute pathophysiological events that occur in the brain within the first 72 hours of aneurysmal SAH. The pathology underlying DCI may involve large artery vasospasm and/or microcirculatory disturbances by microvasospasm, microthrombosis, dysfunction of venous outflow and compression of microvasculature by vasogenic or cytotoxic tissue edema. Recent clinical evidence has shown that large artery vasospasm is not the only cause of DCI, and that both large artery vasospasm-dependent and -independent cerebral infarction causes poor outcome. Animal studies suggest that mechanisms of vasospasm may differ between large artery and arterioles or capillaries, and that many kinds of cells in the vascular wall and brain parenchyma may be involved in the pathogenesis of microcirculatory disturbances. The impairment of the paravascular and glymphatic systems also may play important roles in the development of DCI. As pathological mediators for DCI, glutamate and several matricellular proteins have been investigated in addition to inflammatory molecules. Glutamate is involved in excitotoxicity contributing to cortical spreading ischemia and epileptic activity-related events. Microvascular dysfunction is an attractive mechanism to explain the cause of poor outcomes independently of large cerebral artery vasospasm, but needs more studies to clarify the pathophysiologies or mechanisms and to develop a novel therapeutic strategy.

Prognostic factors varying with age in patients with aneurysmal subarachnoid hemorrhage

With the advent of an aging society, more elderly patients with aneurysmal subarachnoid hemorrhage (aSAH) have been treated. We investigated if prognostic factors differ with age in aSAH patients. In a prospectively maintained aSAH database at multiple institutions from 2013 to 2016, 238 patients who underwent clipping or coiling for a ruptured aneurysm within 48 h of onset were divided into elderly (≥75 years; 57 patients) and non-elderly groups, or categorized into 4-age groups (<54, 55-64, 65-74, and ≥75 years). Prognostic factors and clinical characteristics were retrospectively analyzed. The elderly group had a higher incidence of pre-morbidities, co-morbidities, poor admission World Federation of Neurological Surgeons (WFNS) grades, modified Fisher grade 4, and resultantly 90-day poor outcomes (modified Rankin scale [mRS] 3-6). Multivariate logistic regression analyses revealed that independent determinants for poor outcomes were hypertension and modified Fisher grade 4 in the elderly group, and admission WFNS grades IV-V, systemic complications, non-procedural cerebral infarction and shunt-dependent chronic hydrocephalus in the non-elderly group. The 4-age group analyses showed that higher age group was more frequently associated with the prognostic factors. As higher age itself causes poor outcomes and more association of prognostic factors, prognostic factors in elderly patients may be rather limited.

Mechanisms of neuroinflammation and inflammatory mediators involved in brain injury following subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating cerebrovascular disorder. Neuroinflammation is a critical cause of brain injury following SAH in both acute and chronic phases. While accumulating evidence has shown that therapies targeting neuroinflammation exerted beneficial effects in experimental SAH, there is little clinical evidence. One of the factors making neuroinflammation complicated is that inflammatory signaling pathways and mediators act as protective or detrimental responses at different phases. In addition, biomarkers to detect neuroinflammation are little known in clinical settings. In this review, first, we discuss how the inflammatory signaling pathways contribute to brain injury and other secondary pathophysiological changes in SAH. Damage-associated molecular patterns arising from mechanical stress, transient global cerebral ischemia, red blood cell breakdown and delayed cerebral ischemia following SAH trigger to activate pattern recognition receptors (PRRs) such as Toll-like receptors, nucleotide-binding oligomerization domain-like receptors, and receptors for advanced glycation end products. Most of PRRs activate common downstream signaling transcriptional factor nuclear factor-κΒ and mitogen-activated protein kinases, releasing pro-inflammatory mediators and cytokines. Next, we focus on how pro-inflammatory substances play a role during the course of SAH. Finally, we highlight an important inducer of neuroinflammation, matricellular protein (MCP). MCPs are a component of extracellular matrix and exert beneficial and harmful effects through binding to receptors, other matrix proteins, growth factors, and cytokines. Treatment targeting MCPs is being proved efficacious in pre-clinical models for preventing brain injury including neuroinflammation in SAH. In addition, MCPs may be a candidate of biomarkers predicting brain injury following SAH in clinical settings.

Plasma Periostin and Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

Delayed cerebral ischemia (DCI) is a serious complication of aneurysmal subarachnoid hemorrhage (SAH). Matricellular protein periostin (POSTN) has been found to be upregulated and linked with early brain injury after experimental SAH. The aim of the present study was to investigate the relationship between plasma POSTN levels and various clinical factors including serum levels of C-reactive protein (CRP), an inflammatory marker, in 109 consecutive SAH patients whose POSTN levels were measured at days 1-12 after aneurysmal obliteration. DCI developed in 16 patients associated with higher incidence of angiographic vasospasm, cerebral infarction, and 90-day worse outcomes. POSTN levels peaked at days 4-6 before DCI development. Cerebrospinal fluid (CSF) drainage was associated with reduced POSTN levels, but did not influence CRP levels. There was no correlation between POSTN levels and other treatments or CRP levels. To predict DCI development, receiver-operating characteristic curves indicated that the most reasonable cutoff POSTN levels were obtained at days 1-3 in patients without CSF drainage (80.5 ng/ml; specificity, 77.6%; sensitivity, 85.7%). Multivariate analyses using variables obtained by day 3 revealed that POSTN level was an independent predictor of DCI. POSTN levels over the cutoff value were associated with higher incidence of DCI, but not angiographic vasospasm. This study shows for the first time that CSF drainage may reduce plasma POSTN levels, and that POSTN levels may increase prior to the development of DCI with and without vasospasm irrespective of systemic inflammatory reactions in clinical settings. These findings suggest POSTN as a new therapeutic molecular target against post-SAH DCI.

Potential therapeutic molecular targets for blood-brain barrier disruption after subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage remains serious hemorrhagic stroke with high morbidities and mortalities. Aneurysm rupture causes arterial bleeding-induced mechanical brain tissue injuries and elevated intracranial pressure, followed by global cerebral ischemia. Post-subarachnoid hemorrhage ischemia, tissue injuries as well as extravasated blood components and the breakdown products activate microglia, astrocytes and Toll-like receptor 4, and disrupt blood-brain barrier associated with the induction of many inflammatory and other cascades. Once blood-brain barrier is disrupted, brain tissues are directly exposed to harmful blood contents and immune cells, which aggravate brain injuries furthermore. Blood-brain barrier disruption after subarachnoid hemorrhage may be developed by a variety of mechanisms including endothelial cell apoptosis and disruption of tight junction proteins. Many molecules and pathways have been reported to disrupt the blood-brain barrier after subarachnoid hemorrhage, but the exact mechanisms remain unclear. Multiple independent and/or interconnected signaling pathways may be involved in blood-brain barrier disruption after subarachnoid hemorrhage. This review provides recent understandings of the mechanisms and the potential therapeutic targets of blood-brain barrier disruption after subarachnoid hemorrhage.