Hemostasis and fibrinolysis activation after subarachnoid hemorrhage

Emerging Advances in the Management of Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage: A Narrative Review

Background/Objectives: Aneurysmal subarachnoid hemorrhage (aSAH) remains a life-threatening cerebrovascular event with high rates of mortality and long-term morbidity. Among its complications, delayed cerebral ischemia (DCI) is a major contributor to poor clinical outcomes. Although cerebral vasospasm has traditionally been considered the primary mechanism underlying DCI, recent studies have revealed the multifactorial nature of this condition. This review aims to provide a comprehensive overview of the pathophysiology, preventive strategies, and current treatment options for DCI following aSAH. Methods: A narrative literature review was conducted using the PubMed database to identify peer-reviewed articles relevant to the prevention and treatment of DCI following aSAH. The search strategy employed the following terms: ("Subarachnoid Hemorrhage" [MeSH]) AND "Delayed Cerebral Ischemia" AND ("Prevention and Control" [Subheading] OR "Secondary Prevention" [MeSH]). This search strategy was designed to capture studies addressing both pharmacological and non-pharmacological preventive measures for DCI. Results: A comprehensive PubMed search identified a total of 113 relevant articles. Among these, 40 publications primarily addressed pharmacological interventions, while 22 focused on neuromonitoring techniques. An additional 20 articles explored the pathophysiological mechanisms underlying DCI, and 15 involved preclinical studies utilizing animal models. The remaining 16 articles encompassed diverse topics, including prophylactic endovascular therapies, newly proposed definitions of DCI, treatment algorithm development, functional outcome analyses, and entries in clinical trial registries. Emerging evidence highlights that vasospasm alone does not account for all cases of DCI. Pharmacological approaches such as nimodipine, clazosentan, and fasudil have shown varying degrees of efficacy. Circulatory management and removal of subarachnoid hematoma via CSF drainage or thrombolytics may reduce DCI risk, although their impact on long-term neurological outcomes remains controversial. Endovascular therapy and adjunctive agents such as cilostazol or anticoagulants have demonstrated potential but require further validation through large-scale trials. Conclusions: Effective DCI prevention and treatment require a multimodal approach targeting diverse pathological mechanisms beyond vasospasm. Improved risk stratification, early detection, and individualized therapy are essential for advancing the management of patients with aSAH.

Tranexamic acid for patients with aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis of 2991 patients

OBJECTIVE

We aimed to synthesize evidence from published clinical trials on the efficacy and safety of tranexamic acid (TXA) administration in patients with aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

We followed the standard methods of the Cochrane Handbook of Systematic Reviews for interventions and the PRISMA statement guidelines 2020 when conducting and reporting this study. A computer literature search of PubMed, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials was conducted from inception until 1 January 2022. We selected observational studies and clinical trials comparing TXA versus no TXA in aSAH patients. Data of all outcomes were pooled as the risk ratio (RR) with the corresponding 95% confidence intervals in the meta-analysis models.

RESULTS

Thirteen studies with a total of 2991 patients were included in the analysis. TXA could significantly cut the risk of rebleeding (RR 0.56, 95% CI 0.44 to 0.72) and mortality from rebleeding (RR 0.60, 95% CI 0.39 to 0.92, p = 0.02). However, TXA did not significantly improve the overall mortality, neurological outcome, delayed cerebral ischemia, or hydrocephalus (all p > 0.05). In terms of safety, no significant adverse events were reported. No statistical heterogeneity or publication bias was found in all outcomes.

CONCLUSION

In patients with aSAH, TXA significantly reduces the incidence of rebleeding and mortality from rebleeding. However, current evidence does not support any benefits in overall mortality, neurological outcome, delayed cerebral ischemia, or hydrocephalus.

Initial Experience with a New Self-Expanding Open-Cell Stent System with Antithrombotic Hydrophilic Polymer Coating (pEGASUS Stent) in the Treatment of Wide-Necked Intracranial Aneurysms

PURPOSE

We report our initial experience with endovascular embolization of intracranial aneurysms using this new self-expanding open-cell stent system (pEGASUS stent system) with the antithrombogenic hydrophilic polymer coating.

MATERIALS AND METHODS

We retrospectively reviewed all patients treated with stent-assisted coiling or the Woven EndoBridge device using the pEGASUS stent system between September 2022 and June 2023. Demographic, clinical, and angiographic data were analyzed as well as short-term follow-up, including procedural complication rates and aneurysmal occlusion rates using the Raymond-Roy occlusion classification (RROC).

RESULTS

Twelve patients with 12 wide-necked intracranial aneurysms were treated with the pEGASUS stent system, including 2 acutely ruptured aneurysms embolized in an emergency setting. The treated aneurysms were located at the anterior communicating artery (25.0%), the basilar artery (50.0%), the middle cerebral artery (16.7%), and the internal carotid artery (8.3%). All stents were deployed successfully. Immediate complete aneurysmal occlusion (RROC class I) was achieved in 83.3% (10/12) and near-complete occlusion (RROC II) in 16.7% (2/12). No periprocedural complications occurred in patients treated in the elective setting. A single case of intraoperative in-stent thrombus formation occurred during the treatment of an acutely ruptured basilar aneurysm and was resolved with intravenous Tirofiban. No other periprocedural complications occurred. Eleven out of 12 patients were available for follow up (mean 7.4 months). Complete aneurysmal occlusion without in-stent stenosis (ISS) was seen in 10 patients (90.9%). One patient (9.1%) showed aneurysmal reperfusion (RROC IIIb) with asymptomatic moderate ISS.

CONCLUSION

Our initial results demonstrate that the pEGASUS stent system appears to be a safe and effective device for stent assisted embolization of wide-necked intracranial aneurysms. More data is necessary to evaluate long-term follow-up.

The association between hemoglobin concentration and clinical outcomes after aneurysmal subarachnoid hemorrhage: Insights from the LongTEAM registry

OBJECTIVE

The aim of this study is to explore whether preoperative hemoglobin levels could serve as a prospective biomarker for early brain injury in patients with aneurysmal subarachnoid hemorrhage (aSAH). This investigation seeks to discern its association with postoperative complications and unfavorable clinical outcomes.

METHODS

We conducted a comprehensive analysis of data derived from the LongTeam registry, including patients with aSAH diagnosed between January 2015 and September 2021. These patients were stratified into three distinct groups based on their hemoglobin levels: anemic, standard, and elevated HGB. We employed logistic models featuring spline transformations to assess the relationship between HGB levels and in-hospital complications. Furthermore, a multivariate Cox proportional hazard model was employed to estimate the impact of elevated hemoglobin levels on the hazard function, which was elucidated through Kaplan-Meier curves.

RESULTS

Our study comprised a total of 988 patients, among whom 115 (11.6%) presented preoperative anemia, and 63 (6.4%) exhibited elevated preoperative HGB levels. Following adjustments for potential confounding factors, no significant disparity in risk was evident between anemic patients and those with standard HGB levels. However, individuals with elevated HGB levels displayed a heightened incidence and an increased risk of developing deep vein thrombosis (DVT, odds ratio [OR] = 2.39, 95% confidence interval [CI] = 1.16-4.91, p = 0.018; hazard ratio [HR] = 2.05, 95% CI 1.08-3.92, p = 0.015). Aberrant HGB concentrations did not demonstrate an association with other clinical outcomes.

CONCLUSION

Our findings emphasize that abnormal HGB levels show no association with adverse outcomes at the 90 days mark after accounting for clinical confounding factors in patients with aSAH. Simultaneously, the study illuminates the potential of HGB as an early indicator for identifying patients at a heightened risk of developing DVT.

Increased blood coagulation is associated with poor neurological outcome in aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Patients with aneurysmal subarachnoid hemorrhage (aSAH) have demonstrated increased blood coagulation which is thought to contribute to delayed cerebral ischemia (DCI) and to a worse outcome. Therefore, we sought to determine whether this increased blood coagulation, detectable with rotational thromboelastometry (ROTEM), was associated with DCI and neurological outcome.

METHODS

We conducted a prospective observational study of 60 consecutive adult aSAH patients. ROTEM's EXTEM and FIBTEM assays and D-dimer were analyzed at admission and post-bleed days (PBDs) 2-3, 4-5, 7-8, and 11-12. ROTEM's clot formation time (CFT) represents the stabilization of the clot, and the maximum clot firmness (MCF) the maximum clot strength. Glasgow Outcome Scale extended (GOSe) at three months determined the neurological outcome.

RESULTS

DCI incidence was 41.7%. EXTEM-CFT was significantly shorter in patients with unfavorable neurological outcome (GOSe 1-4) on PBDs 4-5 and 7-8, p < 0.05, respectively. FIBTEM-MCF was significantly higher in patients with unfavorable neurological outcomes on PBD 4-5 (p < 0.05), PBD 7-8 (p < 0.05), and PBD 11-12 (p < 0.05). EXTEM-CFT decreased, and FIBTEM-MCF rose during the study period in all patients. Patients with unfavorable neurological outcome had a higher D-dimer at all studied time points, p < 0.05. No difference was found in the ROTEM parameters or D-dimer when assessing patients with and without DCI.

CONCLUSIONS

Patients were in a state of increased blood coagulation after aSAH, with those with unfavorable neurological outcome being more coagulable than those with favorable outcome. However, increased blood coagulation was not associated with DCI.

CLINICALTRIALS

gov, NCT03985176.

Association between D-dimer levels and long-term mortality in patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE

D-dimer is a marker for hypercoagulability and thrombotic events. The authors sought to investigate whether D-dimer levels predicted long-term mortality in patients with aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

This was a retrospective study of patients with aSAH in West China Hospital, Sichuan University, between December 2013 and June 2019. D-dimer levels were measured within 24 hours after admission and were grouped by quartiles. The primary outcome was long-term mortality. Patient deaths were determined through the Household Registration Administration System in China, with a median of 4.4 years of follow-up.

RESULTS

This study included 2056 patients. Compared with patients with the lowest quartile (0.00-0.97 mg/L) of D-dimer levels, the odds of long-term mortality were significantly higher in all other patients, including those with D-dimer levels between 0.97 mg/L and 1.94 mg/L (adjusted hazard ratio [aHR] 1.85, 95% CI 1.32-2.60), those with D-dimer levels between 1.94 mg/L and 4.18 mg/L (aHR 1.94, 95% CI 1.40-2.70), and those patients with the highest quartile (> 4.18 mg/L) of D-dimer levels (aHR 2.35, 95% CI 1.70-3.24; p < 0.001). Similar results were observed for the endpoints of 1-year mortality and long-term mortality in 1-year survivors.

CONCLUSIONS

Elevated D-dimer levels at admission were associated with short-term and long-term mortality. This biomarker could be considered in future risk nomograms for long-term outcomes and might support future management decisions.

Hemostasis and Fibrinolysis following Aneurysmal Subarachnoid Hemorrhage: A Systematic Review on Additional Knowledge from Dynamic Assays and Potential Treatment Targets

Mortality after aneurysmal subarachnoid hemorrhage (aSAH) is augmented by rebleeding and delayed cerebral ischemia (DCI). A range of assays evaluating the dynamic process of blood coagulation, from activation of clotting factors to fibrinolysis, has emerged and a comprehensive review of hemostasis and fibrinolysis following aSAH may reveal targets of treatment. We conducted a systematic review of existing literature assessing coagulation and fibrinolysis following aSAH, but prior to treatment. PubMed, Embase, and Web of Science were searched on November 18, 2020, without time boundaries. In total, 45 original studies were eventually incorporated into this systematic review, divided into studies presenting data only from conventional or quantitative assays (n = 22) and studies employing dynamic assays (n = 23). Data from conventional or quantitative assays indicated increased platelet activation, whereas dynamic assays detected platelet dysfunction possibly related to an increased risk of rebleeding. Secondary hemostasis was activated in conventional, quantitative, and dynamic assays and this was related to poor neurological outcome and mortality. Studies systematically investigating fibrinolysis were sparse. Measurements from conventional or quantitative assays, as well as dynamic fibrinolysis assays, revealed conflicting results with normal or increased lysis and changes were not associated with outcome. In conclusion, dynamic assays were able to detect reduced platelet function, not revealed by conventional or quantitative assays. Activation of secondary hemostasis was found in both dynamic and nondynamic assays, while changes in fibrinolysis were not convincingly demonstrable in either dynamic or conventional or quantitative assays. Hence, from a mechanistic point of view, desmopressin to prevent rebleeding and heparin to prevent DCI may hold potential as therapeutic options. As changes in fibrinolysis were not convincingly demonstrated and not related to outcome, the use of tranexamic acid prior to aneurysm closure is not supported by this review.

Prognostic value of albumin-fibrinogen ratio in subarachnoid hemorrhage patients

ABSTRACT

Inflammation plays an important role in the pathophysiology of subarachnoid hemorrhage (SAH). Recent studies have indicated that the albumin to fibrinogen ratio (AFR) is a useful biomarker of inflammation.This research aimed to determine the ability of AFR to predict the prognosis of patients with SAH.A total of 440 patients with SAH who had been diagnosed within 72 hours of symptom onset were retrospectively reviewed. Clinical findings and laboratory data were retrieved from the hospital database. Functional outcome was measured according to the modified Rankin scale at 30 days. Logistic regression analysis was used to evaluate the correlation between AFR and the prognosis of patients with SAH. Receiver operating characteristic (ROC) analysis was performed to determine the prognostic ability of AFR at admission to predict the 30-day outcomes.The average age of all 440 patients with SAH was 56.75 ± 11.19 years and 31.4% (138) were male. Of these patients, 161 exhibited unfavorable outcomes at 30 days. According to the multivariate logistic regression analysis, the AFR was positively correlated with the outcome of patients with SAH (odds ratio 0.939, 95% confidence interval 0.885-0.996, P = .038). The ROC analysis revealed an area under the curve of 0.713 for AFR's ability to predict the 30-day outcomes.AFR is independently associated with the outcome of SAH patients. As a parameter that can be easily assessed at admission, AFR could be used to help the decision-making of clinical treatment.

Predictors of deep-vein thrombosis in subarachnoid hemorrhage: a retrospective analysis

BACKGROUND

Subarachnoid hemorrhage is a severe subtype of hemorrhagic stroke, and deep-vein thrombosis is a frequent complication detected in these patients. In addition to other well-established risk factors, the early activation of coagulation systems present in patients with subarachnoid hemorrhage could potentially play a role in the incidence of deep-vein thrombosis. This study aims to identify possible predictors for deep-vein thrombosis related to subarachnoid hemorrhage.

METHODS

We conducted a retrospective cohort study on patients with a diagnosis of subarachnoid hemorrhage who presented to our institution between 1 January 2014 and 1 August 2018. We reviewed electronic medical records and analyzed several parameters such as Fisher scale, World Federation of Neurosurgical Surgeons scale, aneurysm site, surgical or endovascular treatment, decompressive craniectomy, vasospasm, infection (meningitis and pneumonia), presence of motor deficit, length of stay in the ICU, length of hospital stay, number of days under ventilator support, d-dimer at hospitalization, and the time to thromboprophylaxis (days).

RESULTS

The univariate analysis showed that intraparenchymal cerebral hemorrhage, d-dimer at hospitalization, the time to thromboprophylaxis, motor deficit, and aneurysm located at the internal carotid artery were statistically significant factors. Intraparenchymal cerebral hemorrhage (OR 2,78 95%CI 1.07-7.12), motor deficit (OR 3.46; 95%CI 1.37-9.31), and d-dimer at hospitalization (OR 1.002 95% CI 1.001-1.003) were demonstrated as independent risk factors for deep-vein thrombosis. Length of hospital stay was also found to be significantly longer in patients who developed deep-vein thrombosis (p value 0.018).

CONCLUSION

Elevated d-dimer level at the time of hospitalization, motor deficit, and the presence of an intraparenchymal hemorrhage are independent risk factors for deep-vein thrombosis. Patients with DVT also had a significantly longer hospital stay. Even though further studies are needed, patients with elevated d-dimer at hospitalization and intraparenchymal cerebral hemorrhage may benefit from a more aggressive screening strategy for deep-vein thrombosis.

Risk of Ipsilateral Deep Vein Thrombosis After Use of AngioSeal Closure Device in Aneurysmal Subarachnoid Hemorrhage Patients

BACKGROUND

Deep vein thrombosis (DVT) is a known complication in patients with aneurysmal subarachnoid hemorrhage (aSAH). This study investigated the association between use of the AngioSeal (St. Jude Medical, Minnetonka, MN) vascular closure device and the risk of ipsilateral and any DVT event after angiography in patients with aSAH.

METHODS

We conducted a review of our institutional cerebral angiography database for the years 2005-2018 to identify all adult patients who underwent angiography for aSAH. We compared the incidence of DVT (occurring within 14 days) between aSAH patients who underwent manual compression versus the AngioSeal closure device.

RESULTS

A total of 459 aSAH patients underwent angiography; 262 underwent manual compression (57.1%) and 197 received AngioSeal (42.9%). There was a 3.4% rate of ipsilateral DVT in the manual compression group and 7.6% in the AngioSeal closure device group (χ2 test, P = 0.04). Similarly, the rate of any DVT was 8.8% for manual compression and 16.8% for patients who received AngioSeal (χ2 test, P = 0.01). On multivariate analysis, AngioSeal remained a significant independent predictor of ipsilateral DVT (odds ratio 2.4, P = 0.04) and any DVT (odds ratio 2.3, P = 0.01).

CONCLUSIONS

In aSAH patients undergoing cerebral angiographic procedures with access through the femoral artery, the use of AngioSeal closure device was found to be associated with a significantly increased risk of ipsilateral DVT within 14 days.

Nonindex Readmission After Ruptured Brain Aneurysm Treatment Is Associated with Higher Morbidity and Repeat Readmission

BACKGROUND

Aneurysmal subarachnoid hemorrhage (aSAH) requires complex multidisciplinary care. After initial treatment (index hospital), readmission to a different hospital (nonindex) can compromise quality of care, resulting in increased morbidity. We aimed to evaluate factors associated with nonindex readmission and evaluate association of nonindex hospital readmission on outcomes in patients with ruptured aneurysm.

METHODS

Readmissions within 90 days after aSAH treatment were identified in the 2010-2014 Nationwide Readmissions Database. Multivariable logistic regression identified patient and hospital characteristics associated with nonindex readmission. Separate multivariable models determined increased morbidity or risk of second readmission for nonindex readmissions.

RESULTS

A total of 9254 patients who underwent treatment of ruptured aneurysms from 2010 to 2014 were identified. Of these, 1985 (21.5%) were readmitted within 90 days. Three hundred and fifty-five of these readmissions (17.9%) occurred to nonindex hospitals. Patients that were discharged to a skilled nursing or other facility (odds ratio [OR], 1.70; 95% confidence interval [CI], 1.27-2.28]) had higher odds of nonindex readmission, whereas patients with private insurance were associated with lower odds of nonindex readmission (OR, 0.65; 95% CI, 0.46-0.92). Patients readmitted to a nonindex (vs. index) hospital were associated with increased likelihood of major complications (OR, 1.71; 95% CI, 1.18-2.48) and second readmissions (OR, 1.51; 95% CI, 1.17-1.96).

CONCLUSIONS

After treatment of a ruptured cerebral aneurysm, 17.9% of readmissions occurred at a nonindex hospital. These patients were at increased risk for major complications or subsequent readmissions, which may be because of care fragmentation. Interventions aimed at improving continuity of care may reduce higher morbidity associated with nonindex readmission.

Evaluation of Vascular Endothelial Growth Factor A and Selected Parameters of Coagulation and Fibrinolysis in a Group of Patients with Subarachnoid Haemorrhage

Introduction. Subarachnoid hemorrhage (SAH) is currently one of the most serious diseases of the central nervous system. To reduce the negative consequences of SAH and help clinicians to assess the patient's condition, there are attempts to search for new diagnostic markers, which quickly and accurately allow for the proper diagnosis. The aim of this research was the concentration and activity of Vascular Endothelial Growth Factor A (VEGF-A) and selected parameters of coagulation and fibrinolysis in the blood of patients with SAH. Serum levels of VEGF-A in patients diagnosed with SAH are measured to assess the correlation between VEGF-A and the clinical condition of patient. This may help with proper therapeutics and better prognosis. Methods. The study involved 85 patients with subarachnoid hemorrhage. The control group consisted of 45 healthy subjects, sex and age matched. The following parameters were determined: APTT (Activated Partial Thromboplastin Time), INR (International Normalized Ratio), D-dimers and fibrinogen concentration, and the concentration of VEGF-A by ELISA (R&D USA). Results. The average concentration of VEGF-A in the study group was significantly lower compared to the control group. The D-dimer concentration was higher in patients with SAH but the difference was not significant. Coagulation parameters such as INR, APTT, and fibrinogen did not show significant differences between investigated groups. Conclusions. VEGF-A cannot be an independent marker of SAH. Selected parameters of coagulation and fibrinolysis such as D-dimers, INR, APTT, and fibrinogen should not be used as markers of SAH.

CT perfusion imaging of cerebral microcirculatory changes following subarachnoid hemorrhage in rabbits: Specific role of endothelin-1 receptor antagonist

BACKGROUND

Cerebral vasospasm may lead to delayed ischemic neurological deficits following subarachnoid hemorrhage (SAH). Endothelin (ET-1) is an important factor participating in cerebral vasospasm underlying SAH. We used a specific endothelin receptor antagonist, BQ123 to assess the specific role of endothelin-1 receptor antagonist in cerebral vasospasm in a rabbit model of SAH by examining plasma ET-1 levels and the principal CT perfusion (CTP) parameters pertinent to the hemodynamic status of microcirculation following SAH.

METHODS

102 male New Zealand white rabbits were divided into control, SAH and SAH + BQ123 intervention group (BQ123 group). Rabbit SAH model was established by double hemorrhage injection of autologous blood into the cisterna magna; Aquilion ONE was used to collect cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) which were used to evaluate cerebral microcirculation hemodynamics; Elisa was used to assess plasma ET-1 levels. Data were collected on days 1, 4, 7 and 14 following SAH, respectively.

RESULTS

Compared with the control group, the CBF in the SAH group was significantly lower, while the MTT was significantly higher. The CBF decreased on the 4th day and reached the lowest on the 7th day. The MTT began to rise on the 4th day and peaked on the 7th day. While in the BQ123 intervention group, the CBF significantly increased while the MTT significantly decreased on the 1st and the 4th days, respectively. Compared with SAH group, plasma ET-1 levels in BQ123 group significantly increased on the earlier (1st and 4th days) but not later days (between the 7th and 14th days). In addition, the inflammatory infiltration of brain tissues in rabbits treated with BQ123 post-SAH was significantly reduced compared with SAH group.

CONCLUSION

CTP can quantify the therapeutic effect of BQ123 after SAH; Selective blockade of ET-1 endothelin receptor, BQ123 significantly improved microcirculatory perfusion along with a reduction in resultant vasogenic inflammatory responses. The effect of BQ123 on the cerebral microcirculation was lobe dependent.

Unique Contribution of Haptoglobin and Haptoglobin Genotype in Aneurysmal Subarachnoid Hemorrhage

Survivors of cerebral aneurysm rupture are at risk for significant morbidity and neurological deficits. Much of this is related to the effects of blood in the subarachnoid space which induces an inflammatory cascade with numerous downstream consequences. Recent clinical trials have not been able to reduce the toxic effects of free hemoglobin or improve clinical outcome. One reason for this may be the inability to identify patients at high risk for neurologic decline. Recently, haptoglobin genotype has been identified as a pertinent factor in diabetes, sickle cell, and cardiovascular disease, with the Hp 2-2 genotype contributing to increased complications. Haptoglobin is a protein synthesized by the liver that binds free hemoglobin following red blood cell lysis, and in doing so, prevents hemoglobin induced toxicity and facilitates clearance. Clinical studies in patients with subarachnoid hemorrhage indicate that Hp 2-2 patients may be a high-risk group for hemorrhage related complications and poor outcome. We review the relevance of haptoglobin in subarachnoid hemorrhage and discuss the effects of genotype and expression levels on the known mechanisms of early brain injury (EBI) and cerebral ischemia after aneurysm rupture. A better understanding of haptoglobin and its role in preventing hemoglobin related toxicity should lead to novel therapeutic avenues.

Dual antiplatelet therapy in aneurysmal subarachnoid hemorrhage: association with reduced risk of clinical vasospasm and delayed cerebral ischemia

OBJECTIVE Clinical vasospasm and delayed cerebral ischemia (DCI) are devastating complications of aneurysmal subarachnoid hemorrhage (aSAH). Several theories involving platelet activation have been postulated as potential explanations of the development of clinical vasospasm and DCI. However, the effects of dual antiplatelet therapy (DAPT; aspirin and clopidogrel) on clinical vasospasm and DCI have not been previously investigated. The objective of this study was to evaluate the effects of DAPT on clinical vasospasm and DCI in aSAH patients. METHODS Analysis of patients treated for aSAH during the period from July 2009 to April 2014 was performed in a single-institution retrospective study. Patients were divided into 2 groups: patients who underwent stent-assisted coiling or placement of flow diverters requiring DAPT (DAPT group) and patients who underwent coiling only without DAPT (control group). The frequency of symptomatic clinical vasospasm and DCI and of hemorrhagic complications was compared between the 2 groups, utilizing univariate and multivariate logistic regression. RESULTS Of 312 aSAH patients considered for this study, 161 met the criteria for inclusion and were included in the analysis (85 patients in the DAPT group and 76 patients in the control group). The risks of clinical vasospasm (OR 0.244, CI 95% 0.097-0.615, p = 0.003) and DCI (OR 0.056, CI 95% 0.01-0.318, p = 0.001) were significantly lower in patients receiving DAPT. The rates of hemorrhagic complications associated with placement of external ventricular drains and ventriculoperitoneal shunts were similar in both groups (4% vs 2%, p = 0.9). CONCLUSIONS The use of DAPT was associated with a lower risk of clinical vasospasm and DCI in patients treated for aSAH, without an increased risk of hemorrhagic complications.

The Role of Thromboinflammation in Delayed Cerebral Ischemia after Subarachnoid Hemorrhage

Delayed cerebral ischemia (DCI) is a major determinant of patient outcome following aneurysmal subarachnoid hemorrhage. Although the exact mechanisms leading to DCI are not fully known, inflammation, cerebral vasospasm, and microthrombi may all function together to mediate the onset of DCI. Indeed, inflammation is tightly linked with activation of coagulation and microthrombi formation. Thromboinflammation is the intersection at which inflammation and thrombosis regulate one another in a feedforward manner, potentiating the formation of thrombi and pro-inflammatory signaling. In this review, we will explore the role(s) of inflammation and microthrombi in subarachnoid hemorrhage (SAH) pathophysiology and DCI, and discuss the potential of targeting thromboinflammation to prevent DCI after SAH.

Acute Kidney Injury After Subarachnoid Hemorrhage

BACKGROUND

Acute kidney injury (AKI) is common in critically ill patients and may contribute to poor outcome. Few data are available on the incidence and impact of AKI in patients suffering from nontraumatic subarachnoid hemorrhage (SAH).

METHODS

We reviewed all patients admitted to our Department of Intensive Care with SAH over a 3-year period. Exclusion criteria were time from SAH symptoms to intensive care unit (ICU) admission >96 hours and ICU stay <48 hours. AKI was defined as sustained oligoanuria (urine output <0.5 mL/kg/h for 24 h) or an increase in plasma creatinine (≥0.3 mg/dL or a 1.5-fold increase from baseline level within 48 h). Neurological status was assessed at day 28 using the Glasgow Outcome Scale (GOS) (from 1=death to 5=good recovery; favorable outcome=GOS 4 to 5).

RESULTS

Of 243 patients admitted for SAH during the study period, 202 met the inclusion/exclusion criteria (median age 56 y, 78 male). Twenty-five patients (12%) developed AKI, a median of 8 (4 to 10) days after admission. Independent predictors of AKI were development of clinical vasospasm, and treatment with vancomycin. AKI was more frequent in ICU nonsurvivors than in survivors (11/50 vs. 14/152, P=0.03), and in patients with an unfavorable neurological outcome than in other patients (17/93 vs. 8/109, P=0.03). Nevertheless, in multivariable regression analysis, AKI was not an independent predictor of outcome.

CONCLUSIONS

AKI occurred in >10% of patients after SAH. These patients had more severe neurological impairment and needed more aggressive ICU therapy; AKI did not significantly influence outcome.

Plasma ADAMTS13 activity and von Willebrand factor antigen and activity in patients with subarachnoid haemorrhage

Increased von Willebrand factor (VWF) and reduced ADAMTS13 activity are associated with arterial thrombosis. This may also be the culprit mechanism implicated in delayed cerebral ischaemia after aneurysmal subarachnoid haemorrhage (SAH). It was our objective to determine plasma VWF and ADAMTS13 in patients with SAH and healthy subjects; and to explore the levels of those markers and outcome after SAH. Forty consecutive patients were enrolled between September 2007 and April 2014 in a pilot study. Plasma samples were collected from SAH patients on post-bleed day (PBD) 0, 1, 3, 5, 7 and 10 and healthy controls. VWF antigen (VWFAg) and VWF activity (VWFAc) were determined by enzyme-linked immunoassay and collagen binding assay, respectively. ADAMTS13 activity was determined by the cleavage of a fluorescent substrate. Univariate descriptive statistics and cluster analyses were performed based on outcomes in the group with SAH only. Mean age of SAH patients was 52.4 years (26-84 years) and 30 (75 %) were women. 12/40 (30 %) had a high Hunt and Hess grade (IV-V) and 25 (62.5 %) were treated with coil embolisation. Plasma VWFAg and VWFAc were significantly higher in SAH patients than those in healthy subjects on each PBD (p<0.0001). Concurrently, plasma ADAMTS13 activity in SAH patients was significantly lower than that in healthy subjects (p<0.0001). Among those with SAH, cluster analysis demonstrated that patients with higher VWFAg and VWFAc and/or lower ADAMTS13 activity might be at risk of increased mortality. In conclusion, the relative deficiency of plasma ADAMTS13 activity in SAH patients may associate with worse outcome.

Plasma D-dimer may predict poor functional outcomes through systemic complications after aneurysmal subarachnoid hemorrhage

OBJECTIVE Plasma D-dimer levels elevate during acute stages of aneurysmal subarachnoid hemorrhage (SAH) and are associated with poor functional outcomes. However, the mechanism in which D-dimer elevation on admission affects functional outcomes remains unknown. The aim of this study is to clarify whether D-dimer levels on admission are correlated with systemic complications after aneurysmal SAH, and to investigate their additive predictive value on conventional risk factors for poor functional outcomes. METHODS A total of 187 patients with aneurysmal SAH were retrospectively analyzed from a single-center, observational cohort database. Correlations of plasma D-dimer levels on admission with patient characteristics, initial presentation, neurological complications, and systemic complications were identified. The authors also evaluated the additive value of D-dimer elevation on admission for poor functional outcomes by comparing predictive models with and without D-dimer. RESULTS D-dimer elevation on admission was associated with increasing age, female sex, and severity of SAH. Patients with higher D-dimer levels had increased likelihood of nosocomial infections (OR 1.22 [95% CI 1.07-1.39], p = 0.004), serum sodium disorders (OR 1.11 [95% CI 1.01-1.23], p = 0.033), and cardiopulmonary complications (OR 1.20 [95% CI 1.04-1.37], p = 0.01) on multivariable analysis. D-dimer elevation was an independent risk factor of poor functional outcome (modified Rankin Scale Score 3-6, OR 1.50 [95% CI 1.15-1.95], p = 0.003). A novel prediction model with D-dimer had significantly better discrimination ability for poor outcomes than conventional models without D-dimer. CONCLUSIONS Elevated D-dimer levels on admission were independently correlated with systemic complication, and had an additive value for outcome prediction on conventional risk factors after aneurysmal SAH.

Red Blood Cell Distribution Width is Associated with Poor Clinical Outcome After Subarachnoid Hemorrhage: A Pilot Study

INTRODUCTION

The red cell distribution width (RDW) is a biomarker strongly associated with poor outcome in inflammatory and thrombotic diseases. Subarachnoid hemorrhage (SAH) is both an inflammatory and thrombotic state in which many biomarkers have been studied. In this exploratory pilot study, we sought to determine whether RDW predicts poor outcome in patients with SAH.

METHODS

Patients with moderate-to-severe SAH were prospectively enrolled in an observational study of biomarkers and outcome. CBC, ESR, high sensitivity CRP, D-dimer, and fibrinogen were obtained on post-bleed days (PBD) 1, 3, 5, 7, and 10. Poor outcome was defined as a modified Rankin score of 3-6 at 90-days.

RESULTS

Of 40 patients, 5 (12.5%) died and 19 (47.5%) had a poor outcome. RDW (p = 0.046) when measured serially over the study period, was significantly higher among patients with poor outcome. Maximum RDW (OR 2.3 95% CI 1.2-3.6; p = 0.014) and maximum WBC count (OR 1.29 95% CI 1.04-1.60; p = 0.018) were associated with poor outcome. Stepwise addition of maximum ESR, CRP, D-dimer, and fibrinogen yielded a model with RDW (OR 2.54 95% CI 1.21-5.35; p = 0.014) and fibrinogen (OR 1.01 95% CI 1.002-1.01; p = 0.004) predicting outcome. With addition of age and Hunt and Hess grade, RDW, fibrinogen, and high-grade status remained significantly associated with poor outcome. Use of PBD1 RDW in lieu of maximum RDW, resulted in a similar model.

CONCLUSIONS

An elevated RDW is associated with poor outcome in SAH patients. RDW may be a useful predictor of outcomes after SAH.

Thromboelastography Parameter Predicts Outcome After Subarachnoid Hemorrhage: An Exploratory Analysis

OBJECTIVE

Hypercoagulability after subarachnoid hemorrhage (SAH) is well described and may be platelet mediated. Thromboelastography (TEG) provides a global assessment of coagulation. We sought to determine whether the maximum amplitude (MA) parameter of TEG, a measure of platelet strength and function, is associated with outcome after SAH.

METHODS

One hundred ten TEG analyses were performed for patients with moderate-to-severe SAH and compared with 6 healthy age- and sex-matched controls. TEG indices included MA, G value (G), alpha angle, and thrombus generation and were correlated to functional outcomes and laboratory tests including complete blood count, erythrocyte sedimentation rate, high sensitivity C-reactive protein, fibrinogen, and d-dimer, obtained on post-bleed days (PBDs) 1, 3, 5, 7, and 10.

RESULTS

MA was significantly elevated compared with controls on PBD 3 (70.0 mm ± 4.5 mm vs. 64.1 mm ± 6.5 mm; P = 0.02), PBD 5 (72.6 mm ± 5.3 mm vs. 64.1 mm ± 6.5 mm; P = 0.003), PBD 7 (73.0 mm ± 5.4 mm vs. 64.1 mm ± 6.5 mm; P = 0.003), and PBD 10 (73.4 mm ± 6.0 mm vs. 64.1 mm ± 6.5 mm; P = 0.005). G was significantly elevated compared with controls on PBD 3 (P = 0.03), PBD 5 (P = 0.01), PBD 7 (P = 0.01), and PBD 10 (P = 0.02). The only biomarker associated with poor outcome was CRP. Multivariate logistic regression demonstrated an association between elevated MA and outcome (odds ratio 39.1, P = 0.006) independent of CRP, age, Hunt Hess grade, and transfusion.

CONCLUSIONS

TEG indices are associated with poor outcome after SAH and may identify a platelet-mediated hypercoagulable state. The association between MA and outcome was stronger than that between traditional biomarkers and was independent of age and Hunt Hess grade.

The critical care management of poor-grade subarachnoid haemorrhage

Aneurysmal subarachnoid haemorrhage is a neurological syndrome with complex systemic complications. The rupture of an intracranial aneurysm leads to the acute extravasation of arterial blood under high pressure into the subarachnoid space and often into the brain parenchyma and ventricles. The haemorrhage triggers a cascade of complex events, which ultimately can result in early brain injury, delayed cerebral ischaemia, and systemic complications. Although patients with poor-grade subarachnoid haemorrhage (World Federation of Neurosurgical Societies 4 and 5) are at higher risk of early brain injury, delayed cerebral ischaemia, and systemic complications, the early and aggressive treatment of this patient population has decreased overall mortality from more than 50% to 35% in the last four decades. These management strategies include (1) transfer to a high-volume centre, (2) neurological and systemic support in a dedicated neurological intensive care unit, (3) early aneurysm repair, (4) use of multimodal neuromonitoring, (5) control of intracranial pressure and the optimisation of cerebral oxygen delivery, (6) prevention and treatment of medical complications, and (7) prevention, monitoring, and aggressive treatment of delayed cerebral ischaemia. The aim of this article is to provide a summary of critical care management strategies applied to the subarachnoid haemorrhage population, especially for patients in poor neurological condition, on the basis of the modern concepts of early brain injury and delayed cerebral ischaemia.

Timing of deep vein thrombosis formation after aneurysmal subarachnoid hemorrhage

OBJECT

Deep vein thrombosis (DVT) is a common complication of aneurysmal subarachnoid hemorrhage (aSAH). The time period of greatest risk for developing DVT after aSAH is not currently known. aSAH induces a prothrombotic state, which may contribute to DVT formation. Using repeated ultrasound screening, the hypothesis that patients would be at greatest risk for developing DVT in the subacute post-rupture period was tested.

METHODS

One hundred ninety-eight patients with aSAH admitted to the Oregon Health & Science University Neurosciences Intensive Care Unit between April 2008 and March 2012 were included in a retrospective analysis. Ultrasound screening was performed every 5.2 ± 3.3 days between admission and discharge. The chi-square test was used to compare DVT incidence during different time periods of interest. Patient baseline characteristics as well as stroke severity and hospital complications were evaluated in univariate and multivariate analyses.

RESULTS

Forty-two (21%) of 198 patients were diagnosed with DVT, and 3 (2%) of 198 patients were symptomatic. Twenty-nine (69%) of the 42 cases of DVT were first detected between Days 3 and 14, compared with 3 cases (7%) detected between Days 0 and 3 and 10 cases (24%) detected after Day 14 (p < 0.05). The postrupture 5-day window of highest risk for DVT development was between Days 5 and 9 (40%, p < 0.05). In the multivariate analysis, length of hospital stay and use of mechanical prophylaxis alone were significantly associated with DVT formation.

CONCLUSIONS

DVT formation most commonly occurs in the first 2 weeks following aSAH, with detection in this cohort peaking between Days 5 and 9. Chemoprophylaxis is associated with a significantly lower incidence of DVT.

Hemostasis and fibrinolysis in delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage: a systematic review

Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH) has been associated with microthrombosis, which can result from activated hemostasis, inhibited fibrinolysis, or both. We systematically searched the PUBMED and EMBASE databases to identify hemostatic or fibrinolytic parameters that can be used for the prediction or diagnosis of DCI, or that inform on the pathogenesis of DCI and may serve as treatment targets. We included 24 studies that fulfilled predefined criteria and described 39 biomarkers. Only one study fulfilled predefined criteria for high quality. Since no parameter on admission was associated with DCI and in none of the included studies blood was drawn at the time of clinical deterioration, none of the studied parameters can presently be used for the prediction or diagnosis of DCI. Regarding the pathogenesis of DCI, it was shown that compared with patients without DCI those with DCI had higher levels of von Willebrand factor and platelet activating factor in plasma 5 to 9 days after aSAH, membrane tissue factor in cerebrospinal fluid 5 to 9 days after aSAH, and D-dimer in plasma 11 to 14 days after aSAH. Confirmation in high-quality studies is needed to investigate whether these parameters can serve as targets for new intervention studies.

The pathophysiology and treatment of delayed cerebral ischaemia following subarachnoid haemorrhage

Cerebral vasospasm has traditionally been regarded as an important cause of delayed cerebral ischaemia (DCI) which occurs after aneurysmal subarachnoid haemorrhage, and often leads to cerebral infarction and poor neurological outcome. However, data from recent studies argue against a pure focus on vasospasm as the cause of delayed ischaemic complications. Findings that marked reduction in the incidence of vasospasm does not translate to a reduction in DCI, or better outcomes has intensified research into other possible mechanisms which may promote ischaemic complications. Early brain injury and cell death, blood-brain barrier disruption and initiation of an inflammatory cascade, microvascular spasm, microthrombosis, cortical spreading depolarisations and failure of cerebral autoregulation, have all been implicated in the pathophysiology of DCI. This review summarises the current knowledge about the mechanisms underlying the development of DCI. Furthermore, it aims to describe and categorise the known pharmacological treatment options with respect to the presumed mechanism of action and its role in DCI.

Current management of delayed cerebral ischemia: update from results of recent clinical trials

Subarachnoid hemorrhage (SAH) accounts for 5-7% of all strokes worldwide and is associated with high mortality and morbidity. Even after surgical intervention, approximately 30% of patients develop long-term cognitive and neurological deficits that significantly affect their capacity to return to work or daily life unassisted. Much of this stems from a secondary ischemic phenomenon referred to as delayed cerebral ischemia (DCI). While DCI has been historically attributed to the narrowing of the large basal cerebral arteries, it is now recognized that numerous pathways contribute to its pathogenesis, including microcirculatory dysfunction, microthrombosis, cortical spreading depression, and early brain injury. This paper seeks to summarize some of the key pathophysiological events that are associated with poor outcome after SAH, provide a general overview of current methods of treating SAH patients, and review the results of recent clinical trials directed at improving outcome after SAH. The scientific basis of these studies will be discussed, in addition to the available results and recommendations for effective patient management. Therapeutic methods under current clinical investigation will also be addressed. In particular, the mechanisms by which they are expected to elicit improved outcome will be investigated, as well as the specific study designs and anticipated time lines for completion.

Changes in the coagulation and fibrinolytic system of patients with subarachnoid hemorrhage

The aim of this study was to investigate the dynamic changes in the coagulation and fibrinolytic system with subarachnoid hemorrhage. The blood coagulation enzyme-AT complex (TAT), anticoagulant enzyme (AT), tissue plasminogen activator (tPA), plasminogen activin inhibitor (PAI-1), and mean blood flow velocity were measured. The TAT level was significantly higher 6 h after subarachnoid hemorrhage (SAH), whereas AT was significantly lower. These changes were maintained at 12 h to 1 d after SAH, returned to normal at 3 d, significantly changed again at 7 d to 14 d. The tPA level gradually increased after SAH and peaked at 14 d, and then returned to normal at 21 d. The PAI-1 levels were significantly lower than those in the control group 1 d after SAH gradually increased, and returned to normal at 21 d. In the cerebral vasospasm (CVS) groups, the levels of TAT, and AT significantly changed compared to the non-CVS groups after SAH. The PAI-1 levels were higher at 7 d and 14 d, but the changes were not significant. In groups Fisher III and IV as well as Hunt III to V, the TAT, AT, tPA, and PAI-1 levels were significantly higher than those in both Fisher and Hunt I and II 6 h, 12 h, 1 d, 7 d, and 14 d after SAH. The changes in the coagulation and fibrinolytic system of patients with SAH are correlated with the progress and symptoms of SAH as well as the blood content and CVS.

Brain ischemia in patients with intracranial hemorrhage: pathophysiological reasoning for aggressive diagnostic management

Patients with intracranial hemorrhage have to be managed aggressively to avoid or minimize secondary brain damage due to ischemia, which contributes to high morbidity and mortality. The risk of brain ischemia, however, is not the same in every patient. The risk of complications associated with an aggressive prophylactic therapy in patients with a low risk of brain ischemia can outweigh the benefits of therapy. Accurate and timely identification of patients at highest risk is a diagnostic challenge. Despite the availability of many diagnostic tools, stroke is common in this population, mostly because the pathogenesis of stroke is frequently multifactorial whereas diagnosticians tend to focus on one or two risk factors. The pathophysiological mechanisms of brain ischemia in patients with intracranial hemorrhage are not yet fully elucidated and there are several important areas of ongoing research. Therefore, this review describes physiological and pathophysiological aspects associated with the development of brain ischemia such as the mechanism of oxygen and carbon dioxide effects on the cerebrovascular system, neurovascular coupling and respiratory and cardiovascular factors influencing cerebral hemodynamics. Consequently, we review investigations of cerebral blood flow disturbances relevant to various hemodynamic states associated with high intracranial pressure, cerebral embolism, and cerebral vasospasm along with current treatment options.

Delayed cerebral ischaemia after subarachnoid haemorrhage: looking beyond vasospasm

Despite improvements in the clinical management of aneurysmal subarachnoid haemorrhage over the last decade, delayed cerebral ischaemia (DCI) remains the single most important cause of morbidity and mortality in those patients who survive the initial bleed. The pathological mechanisms underlying DCI are still unclear and the calcium channel blocker nimodipine remains the only therapeutic intervention proven to improve functional outcomes after SAH. The recent failure of the drug clazosentan to improve functional outcomes despite reducing vasoconstriction has moved the focus of research into DCI away from cerebral artery constriction towards a more multifactorial aetiology. Novel pathological mechanisms have been suggested, including damage to cerebral tissue in the first 72 h after aneurysm rupture ('early brain injury'), cortical spreading depression, and microthrombosis. A greater understanding of the significance of these pathophysiological mechanisms and potential genetic risk factors is required, if new approaches to the prophylaxis, diagnosis, and treatment of DCI are to be developed. Furthermore, objective and reliable biomarkers are needed for the diagnosis of DCI in poor grade SAH patients requiring sedation and to assess the efficacy of new therapeutic interventions. The purpose of this article is to appraise these recent advances in research into DCI, relate them to current clinical practice, and suggest potential novel avenues for future research.

Inflammation as a predictor for delayed cerebral ischemia after aneurysmal subarachnoid haemorrhage

BACKGROUND

The mechanism of development of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (SAH) is poorly understood. Inflammatory processes are implicated in the development of ischemic stroke and may also predispose to the development of DCI following SAH. The objective of this study was to test whether concentrations of circulating inflammatory markers (C-reactive protein (CRP), interleukin-6 (IL-6) and interleukin 1 receptor antagonist (IL-1Ra)) were predictive for DCI following SAH. Secondary analyses considered white cell count (WCC) and erythrocyte sedimentation rate (ESR).

METHODS

This was a single-center case-control study nested within a prospective cohort. Plasma inflammatory markers were measured in patients up to 15 days after SAH (initial, peak, average, final and rate of change to final). Cases were defined as those developing DCI. Inflammatory markers were compared between cases and randomly selected matched controls.

RESULTS

Among the 179 participants there were 46 cases of DCI (26%). In primary analyses the rate of change of IL-6 was associated with DCI (OR 2.3 (95% CI 1.1 to 5.0); p=0.03). The final value and rate of change of WCC were associated with DCI (OR 1.2 (95% CI 1.0 to 1.3) and OR 1.3 (95% CI 1.0 to 1.6), respectively). High values of ESR were associated with DCI (OR 2.4 (95% CI 1.3 to 4.6) initial; OR 2.3 (95% CI 1.3 to 4.2) average; OR 2.1 (95% CI 1.1 to 3.9) peak; and OR 2.0 (95% CI 1.2 to 3.3) final value).

CONCLUSIONS

Leucocytosis and change in IL-6 prior to DCI reflect impending cerebral ischemia. The time-independent association of ESR with DCI after SAH may identify this as a risk factor. These data suggest that systemic inflammatory mechanisms may increase the susceptibility to the development of DCI after SAH.

The importance of early brain injury after subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a medical emergency that accounts for 5% of all stroke cases. Individuals affected are typically in the prime of their lives (mean age 50 years). Approximately 12% of patients die before receiving medical attention, 33% within 48 h and 50% within 30 days of aSAH. Of the survivors 50% suffer from permanent disability with an estimated lifetime cost more than double that of an ischemic stroke. Traditionally, spasm that develops in large cerebral arteries 3-7 days after aneurysm rupture is considered the most important determinant of brain injury and outcome after aSAH. However, recent studies show that prevention of delayed vasospasm does not improve outcome in aSAH patients. This finding has finally brought in focus the influence of early brain injury on outcome of aSAH. A substantial amount of evidence indicates that brain injury begins at the aneurysm rupture, evolves with time and plays an important role in patients' outcome. In this manuscript we review early brain injury after aSAH. Due to the early nature, most of the information on this injury comes from animals and few only from autopsy of patients who died within days after aSAH. Consequently, we began with a review of animal models of early brain injury, next we review the mechanisms of brain injury according to the sequence of their temporal appearance and finally we discuss the failure of clinical translation of therapies successful in animal models of aSAH.

Reduced clot-stability during the first 6 hours after aneurysmal subarachnoid haemorrhage--a prospective case-control study

INTRODUCTION

Early rebleeding is an important cause of death and disability following aneurysmal subarachnoid haemorrhage (SAH). Recent studies have shown that 50-90% of the rebleedings occurred within the first 6 hours after the primary bleeding. The mechanism leading to rebleeding remains to be established. In the present prospective case-control study we hypothesize that patients with SAH develop a coagulopathy characterized by reduced clot stability during the early period after the initial bleeding.

METHODS

Patients with aneurysmal SAH was studied with a dynamic clot lysis assay and markers of fibrinolysis and clot stabilizers in blood samples taken within and after 6 hours after onset of bleeding. Results were compared with blood samples from age and gender matched healthy controls.

RESULTS

36 patients were enrolled, 26 patients had blood samples collected within 6 hours after the initial bleeding whereas 10 patients had blood samples taken later than 6 hours after the initial bleeding. Patients demonstrated significantly reduced clot stability during the first 6 hours after initial bleeding. Fibrinolytic activity was increased during the first 6 hours along with the inhibitors of fibrinolysis whereas the modulators of fibrinolysis were reduced or inactivated.

CONCLUSION

During the first 6 hours after SAH patients exhibit reduced clot-stability. Probably a consequence of activated fibrinolysis in combination with reduced or inactivated factor XIII and thrombin-activable fibrinolysis inhibitor.

Microthrombosis after experimental subarachnoid hemorrhage: time course and effect of red blood cell-bound thrombin-activated pro-urokinase and clazosentan

Delayed cerebral ischemia (DCI) is a significant cause of morbidity and mortality for patients surviving the rupture of an intracranial aneurysm. Despite an association between vasospasm and DCI, thrombosis and thromboembolism may also contribute to DCI. In this study we investigate the time course of intravascular microclot formation after experimental subarachnoid hemorrhage (SAH) and assess the effects of the following two drugs on microclot burden: mutant thrombin-activated urokinase-type plasminogen activator (scFv/uPA-T), which is bound to red blood cells for use as a thromboprophylactic agent, and clazosentan, an endothelin antagonist. In the first study, adult male C57BL/6 mice were sacrificed at 24 (n=5), 48 (n=6), 72 (n=8), and 96 (n=3) hours after SAH induced by filament perforation of the anterior cerebral artery. Sham animals (n=5) underwent filament insertion without puncture. In the second study, animals received scFv/uPA-T (n=5) 3 hours after hemorrhage, clazosentan (n=5) by bolus and subcutaneous pump after SAH just prior to skin closure, or a combination of scFv/uPA-T and clazosentan (n=4). Control (n=6) and sham (n=5) animals received saline alone. All animals were sacrificed at 48 hours and underwent intra-cardiac perfusion with 4% paraformaldehyde. The brains were then extracted and sliced coronally on a cryostat and processed for immunohistochemistry. An antibody recognizing thrombin-anti-thrombin complexes was used to detect microclots on coronal slices. Microclot burden was calculated for each animal and compared among groups. Following SAH, positive anti-thrombin staining was detected bilaterally in the following brain regions, in order of decreasing frequency: cortex; hippocampus; hypothalamus; basal ganglia. Few microclots were found in the shams. Microclot burden peaked at 48 hours and then decreased gradually. Animals receiving scFv/uPA-T and scFv/uPA-T+clazosentan had a lower microclot burden than controls, whereas animals receiving clazosentan alone had a higher microclot burden (p<0.005). The overall mortality rate in the time course study was 40%; mortality was highest among control animals in the second study. Intravascular microclots form in a delayed fashion after experimental SAH. Microclots may be safely reduced using a novel form of thromboprophylaxis provided by RBC-targeted scFv/uPA-T and represent a potential target for therapeutic intervention in the treatment of DCI.

Fibrinogen γ' levels in patients with intracerebral hemorrhage

BACKGROUND

The fibrinogen γ' variant (γ') has both antithrombotic and prothrombotic properties when compared to normal fibrinogen. It may therefore be of relevance in intracerebral hemorrhage and intraventricular extension of the bleeding.

OBJECTIVE

To study the role of γ' in intracerebral hemorrhage, and in intraventricular extension of the hemorrhage.

PATIENTS/METHODS

We performed a case-control study in 156 controls and 55 patients with intracerebral hemorrhage, with and without intraventricular extension. Levels of fibrinogen γ' and the γ'/total fibrinogen ratio were measured in all participants.

RESULTS

Levels of γ' were increased in patients with intracerebral hemorrhage when compared with controls (0.40 vs 0.32g/l, p<0.001). The γ'/total fibrinogen ratio was similar in patients and controls (0.092 vs 0.096 p=0.42). There was evidence for an unfavorable outcome in patients with fibrinogen levels in the highest tertile compared with the lowest tertile (OR 4.0, 95%CI 1.1-15.2), and a nonsignificant trend toward unfavorable outcome with higher levels of γ' (p-value for trend=0.06).

CONCLUSIONS

Our study shows that absolute levels of fibrinogen γ' are increased in patients with intracerebral hemorrhage, but relative levels are similar in patients and controls, suggesting that the absolute rise in γ' is an acute phase response.

Early ceasing of intra-aneurysmal contrast opacification during coil embolization in ruptured aneurysms compared with unruptured aneurysms

BACKGROUND

The difference between coil-embolized ruptured and unruptured aneurysms with respect to intra-aneurysmal thrombus formation remains to be determined.

OBJECTIVE

We examined whether there was a difference between ruptured and unruptured coil-embolized aneurysms in the rate and timing of thrombus formation in the aneurysmal sac and discuss the effect of thrombus on the treatment outcome.

METHODS

We evaluated 209 aneurysms with an aneurysmal dome smaller than 10 mm and a neck size less than 4 mm. Of these, 91 (43.5%) were ruptured. We assessed intra-aneurysmal thrombus formation by the coil-packing ratio (CPR): the percentage of coil volume occupying the aneurysmal sac. The initial CPR was defined as the CPR at which contrast influx into the sac ceased and the final CPR as that at the end of the procedure. ΔCPR was calculated as the difference between initial and final CPRs. Embolized aneurysms were evaluated on follow-up angiograms.

RESULTS

The initial CPR was significantly lower in ruptured aneurysms (P < .01), and there was not a significant difference in the final CPR between ruptured and unruptured aneurysms (P = .05). ΔCPR was significantly higher in ruptured aneurysms (P < .01). The rate of aneurysmal recanalization was significantly higher in ruptured aneurysms (P < .05). The incidence of recanalization was high in ruptured aneurysms with low initial CPR and ΔCPR values.

CONCLUSION

In ruptured aneurysms, intra-aneurysmal thrombus formation tends to occur in the earlier stages of coil embolization. In some cases, thrombus formation may inhibit dense coil packing and result in recanalization.

A review of delayed ischemic neurologic deficit following aneurysmal subarachnoid hemorrhage: historical overview, current treatment, and pathophysiology

Delayed ischemic neurologic deficit (DIND) is a serious and poorly understood complication of aneurysmal subarachnoid hemorrhage. Although advances in treatment have improved prognosis for these patients, long-term clinical outcomes remain disappointing. Historically, angiographic vasospasm was thought to result in a DIND, although an increasing body of evidence suggests that this is an oversimplification, because interventions that have effectively targeted angiographic vasospasm have not improved outcome. Consequently, the relationship between angiographic vasospasm and neurologic outcome may be associative rather than causative. Although our understanding of the underlying molecular processes and pathophysiology is improving, responsible mediators or pathways have yet to be identified. The aim of this review is to summarize the key historical events that have helped shape our understanding of the pathophysiology of this phenomenon (microcirculation, autoregulation, microthrombosis, inflammation, apoptosis, spreading depolarization, oxidative stress) and to present the evidence underlying current treatment strategies (hemodynamic therapy, oral nimodipine, endovascular therapy, statins, cerebrospinal fluid drainage, thrombolysis, magnesium) and the translational and clinical research investigating DIND.

Blood coagulation and fibrinolysis after experimental subarachnoid hemorrhage

BACKGROUND

Aneurysmal rebleeding poses a serious risk in patients with subarachnoid hemorrhage (SAH). Studies have shown that antifibrinolytic therapy with tranexamic acid has a dramatic effect on the rate of rebleeding. Therefore, changes in the fibrinolytic system could be hypothesized.

METHODS

We have used an experimental SAH rat model to demonstrate serial changes in the haemostatic system as evaluated by Thromboelastography (TEG).

RESULTS

In the SAH group, a shorter reaction time (R-time) and higher maximum amplitude (MA) were observed. In the saline group, only a shorter R-time was observed.

CONCLUSIONS

The study has shown that a hypercoagulable state is present immediately after experimental SAH is induced as determined by TEG. The reduction in R-time and rise in MA observed in the SAH group indicate that blood in the subarachnoid space is necessary to accomplish a full systemic coagulation response. This abnormality in coagulation profile seems to be a response to the acute traumatic event caused by induction of SAH.

Brain interstitial fluid TNF-alpha after subarachnoid hemorrhage

OBJECTIVE

TNF-alpha is an inflammatory cytokine that plays a central role in promoting the cascade of events leading to an inflammatory response. Recent studies have suggested that TNF-alpha may play a key role in the formation and rupture of cerebral aneurysms, and that the underlying cerebral inflammatory response is a major determinate of outcome following subrarachnoid hemorrhage (SAH).

METHODS

We studied 14 comatose SAH patients who underwent multimodality neuromonitoring with intracranial pressure (ICP) and cerebral microdialysis as part of their clinical care. Continuous physiological variables were time-locked every 8h and recorded at the same point that brain interstitial fluid TNF-alpha was measured in brain microdialysis samples. Significant associations were determined using generalized estimation equations.

RESULTS

Each patient had a mean of 9 brain tissue TNF-alpha measurements obtained over an average of 72h of monitoring. TNF-alpha levels rose progressively over time. Predictors of elevated brain interstitial TNF-alpha included higher brain interstitial fluid glucose levels (beta=0.066, p<0.02), intraventricular hemorrhage (beta=0.085, p<0.021), and aneurysm size >6mm (beta=0.14, p<0.001). There was no relationship between TNF-alpha levels and the burden of cisternal SAH; concurrent measurements of serum glucose, or lactate-pyruvate ratio.

INTERPRETATION

Brain interstitial TNF-alpha levels are elevated after SAH, and are associated with large aneurysm size, the burden of intraventricular blood, and elevation brain interstitial glucose levels.

Association between factor XIII single nucleotide polymorphisms and aneurysmal subarachnoid hemorrhage

Object

Family studies have suggested a role of genetic factors in susceptibility to aneurysmal subarachnoid hemorrhage (aSAH), but the underlying genetic risk factors remain poorly defined. There is an activation of the fibrinolytic system in aSAH, and fibrinolytic markers may be useful in predicting outcome. The authors investigate associations between putative functional variants in genes of importance for fibrinolysis and aSAH and/or outcome following aSAH.

Methods

One hundred eighty-three patients presenting with aSAH at a neurointensive care unit were consecutively recruited. Two healthy controls per case, matched for age, sex, and geographic region, were randomly recruited. Outcome was assessed after 1 year according to the extended Glasgow Outcome Scale. Single nucleotide polymorphisms (SNPs) in the tissue-type plasminogen activator (tPA), plasminogen activator inhibitor type 1 (PAI-1), thrombin activatable fibrinolysis inhibitor (TAFI), and factor XIII (FXIII) genes were investigated.

Results

Participants carrying the FXIII 34Leu allele showed an increased risk of aSAH. When adjusting for smoking and hypertension, 2 haplotypes, differing on either the FXIII Val34Leu or the Pro564Leu position, showed an association to aSAH. No significant association was observed for the tPA -7351 C > T, PAI-1 -675 4G > 5G, or TAFI Ala147Thr SNPs. No specific SNP or haplotype was associated with outcome after aSAH, whereas a weak association was observed for a tPA/PAI-1 genotype combination.

Conclusions

Polymorphisms in the FXIII gene showed association to aSAH. The finding of an increased risk of bleeding in FXIII 34Leu carriers is biologically plausible.

Is D-dimer helpful in evaluating stroke patients? A systematic review

D-dimer (DD) is a fibrin degradation product present in negligible amounts in healthy individuals, but in thrombotic/fibrinolytic conditions substantially increases in plasma. Over the last two decades numerous studies have explored whether DD measurements would help stroke clinicians. An easy, reliable, and inexpensive test for stroke diagnosis, determination of stroke subtype, severity, prognosis, and recurrence risk is being sought. We searched the database, of studies indexed in English on MEDLINE, using the keywords 'cerebral venous thrombosis, D-dimer, deep vein thrombosis, intracerebral hemorrhage, ischemic stroke, outcome, prognosis, and subarachnoid hemorrhage' for relevant studies. Here, we systematically review current evidence on plasma DD levels in patients with ischemic and hemorrhagic strokes, transient ischemic attacks, and cerebral venous thrombosis. Numerous studies showed that patients with various strokes and stroke-related diseases had acutely increased plasma DD levels. Plasma DD levels, however, are neither sensitive nor specific enough to be utilized in stroke diagnostics and cannot replace either clinical or radiological evaluation. Regarding prediction of patient outcome, good clinical evaluation is clearly superior to DD testing.

Coexistence of vasospasm and microembolism detected by transcranial Doppler ultrasonography in a patient with subarachnoid haemorrhage

Delayed cerebral ischaemia as a clinical expression of vasospasm is one of the main complications of subarachnoid haemorrhage. In some cases, ischaemic manifestations can be related to cerebral emboli, but the relationship between vasospasm, damaged endothelial lining, and embolism, remains to be proven. The case is presented of a 56-year-old female patient who, 5 days after the clipping of an aneurysm in the left middle cerebral artery (MCA), suffered transient ischaemic attacks (TIAs) of this arterial territory. Transcranial Doppler ultrasonography showed an increment of the left MCA mean flow velocity, and 12 microembolic signals were detected in 30 mins. The coexistence of microemboli signals with severe vasospasm in the same arterial segment might suggest a causal relationship between cerebral embolism, severity of vasospasm, and TIAs.

Microthrombosis after aneurysmal subarachnoid hemorrhage: an additional explanation for delayed cerebral ischemia

Patients with aneurysmal subarachnoid hemorrhage (SAH) who experience delayed cerebral ischemia (DCI) have an increased risk of poor outcome. Delayed cerebral ischemia is considered to be caused by vasospasm. However, not all patients with DCI have vasospasm. Inversely, not all patients with vasospasm develop clinical symptoms and signs of DCI. In the past, treatments aiming at vasospasm were not successful in preventing ischemia. The purpose of this review is to give an overview of clinical data showing that DCI cannot always be attributed to vasospasm, and to present an in-depth analysis of clinical and autopsy studies on the role of microthrombosis in the pathogenesis of DCI. Clinical studies show that DCI is associated with an activation of the coagulation cascade within a few days after SAH, preceding the time window during which vasospasm occurs. Furthermore, impaired fibrinolytic activity, and inflammatory and endothelium-related processes, lead to the formation of microthrombi, which ultimately result in DCI. The presence of microthrombi is confirmed by autopsy studies. Insight in the pathophysiology of DCI is crucial for the development of effective therapies against this complication. Because multiple pathways are involved, future research should focus on drugs with pleiotropic effects.

Vasospasm as the sole cause of cerebral ischemia: how strong is the evidence?

✓ The authors review literature that challenges the view that vasospasm involving large arteries is the exclusive cause of delayed ischemic neurological deficits (DINDs) following subarachnoid hemorrhage. They discuss alternative mechanisms and review the evidence supporting a potential role for thromboembolism. They conclude that vasospasm and thromboembolism play interrelated and additive roles in the development of DINDs, and that this interaction provides opportunities for novel therapeutic approaches.

Changes in coagulative and fibrinolytic activities in patients with intracranial hemorrhage

OBJECTIVE

To investigate whether any changes occur in the coagulative/fibrinolytic cascade in patients with subarachnoid hemorrhage (SAH) or hypertensive intracerebral hemorrhage (HICH).

DESIGN AND METHODS

Subjects included 143 patients with intracranial hemorrhage (SAH, n = 50; HICH, n = 82; ROSC-SAH [return of spontaneous circulation after cardiopulmonary arrest due to SAH], n = 11). Coagulative and fibrinolytic factors were measured in blood samples taken on admission.

RESULTS

The prothrombin fragment 1+2 level was significantly higher (p < 0.005) in SAH patients than in HICH patients. The fibrinolytic factors (plasmin alpha 2-plasmin inhibitor complex, D-dimer, or fibrinogen degradation products) in SAH and ROSC-SAH were both significantly higher than those in HICH, but the significance of difference was stronger in the case of ROSC-SAH (p < 0.05).

DISCUSSION

Both coagulative and fibrinolytic activities were altered after the onset of SAH. These results demonstrate that the coagulative/fibrinolytic cascade might be activated via different mechanisms in different types of stroke. It remains unclear, however, whether a significant alteration of the fibrinolytic cascade in patients with ROSC-SAH might be a nonspecific phenomenon attributable to the reperfusion after collapse.