Early brain injury after aneurysmal subarachnoid hemorrhage: a multimodal neuromonitoring study

Evaluation of H2S-producing enzymes in cerebrospinal fluid and its relationship with interleukin-6 and neurologic deficits in subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Recent studies have suggested that H₂S may be involved in the pathophysiology of subarachnoid hemorrhage (SAH). Endogenous H₂S is mainly formed by cystathionine β-synthase (CBS), d-amino-acid oxidase (DAO), and 3-mercaptopyruvate sulfotransferase (3-MST) from the substrate cysteine in the central nervous system. In this study, we assessed the expression of CBS, 3-MST, and DAO in cerebrospinal fluid (CSF) from patients with SAH and rats and the expression in the rat brain.

METHODS

CSF samples were collected within 48 h of aneurysm rupture in SAH patients. The CBS, DAO and 3-MST levels in CSF were measured using Western blot analyses, and correlations with the inflammatory parameter Interleukin-6 (IL-6) were assessed. Six months after SAH, the clinical outcomes were assessed.

RESULTS

In human CSF samples, the CBS and DAO protein levels were detected and increased after SAH. However, 3-MST was not detected in the control group CSF but increased after SAH. Strong correlations were observed between the increasing levels of CBS, DAO, and 3-MST and IL-6 2 days after SAH. Furthermore, high CBS, 3-MST and DAO levels in the CSF samples were correlated with poor outcomes at 6 months after SAH onset. We also found that the expression of CBS, DAO and 3-MST in the rat CSF and brain (parietal cortex and hippocampus) increased following SAH. We detected strong correlations between the increases in CBS, 3-MST and IL-6 in the rat CSF and brain samples.

CONCLUSIONS

These results indicate that the upregulated expression of CBS, DAO and 3-MST after SAH was closely associated with the inflammatory response and neurological deficits after SAH.

Early Brain Injury After Poor-Grade Subarachnoid Hemorrhage

PURPOSE OF REVIEW

Over the last years, the focus of clinical and animal research in subarachnoid hemorrhage (SAH) shifted towards the early phase after the bleeding based on the association of the early injury pattern (first 72 h) with secondary complications and poor outcome. This phase is commonly referenced as early brain injury (EBI). In this clinical review, we intended to overview commonly used definitions of EBI, underlying mechanisms, and potential treatment implications.

RECENT FINDINGS

We found a large heterogeneity in the definition used for EBI comprising clinical symptoms, neuroimaging parameters, and advanced neuromonitoring techniques. Although specific treatments are currently not available, therapeutic interventions are aimed at ameliorating EBI by improving the energy/supply mismatch in the early phase after SAH. Future research integrating brain-derived biomarkers is warranted to improve our pathophysiologic understanding of EBI in order to ameliorate early injury patterns and improve patients' outcomes.

Current Options and Future Directions in Immune Therapy for Glioblastoma

Glioblastoma is in need of innovative treatment approaches. Immune therapy for cancer refers to the use of the body's immune system to target malignant cells in the body. Such immune therapeutics have recently been very successful in treating a diverse group of cancerous lesions. As a result, many new immune therapies have gained Food and Drug Administration approval for the treatment of cancer, and there has been an explosion in the study of immune therapeutics for cancer treatment over the past few years. However, the immune suppression of glioblastoma and the unique immune microenvironment of the brain make immune therapeutics more challenging to apply to the brain than to other systemic cancers. Here, we discuss the existing barriers to successful immune therapy for glioblastoma and the ongoing development of immune therapeutics. We will discuss the discovery and classification of immune suppressive factors in the glioblastoma microenvironment; the development of vaccine-based therapies; the use of convection-enhanced delivery to introduce tumoricidal viruses into the tumor microenvironment, leading to secondary immune responses; the emerging use of adoptive cell therapy in the treatment of glioblastoma; and future frontiers, such as the use of cerebral microdialysis for immune monitoring and the use of sequencing to develop patient-specific therapeutics. Armed with a better understanding of the challenges inherent in immune therapy for glioblastoma, we may soon see more successes in immune-based clinical trials for this deadly disease.

Early serum miR-1297 is an indicator of poor neurological outcome in patients with aSAH

Objective: MiRNAs are important regulators of translation and have been described as biomarkers of a number of cardiovascular diseases, including stroke. The purpose of the study was to determine expression levels of serum miR-1297 in patients with aneurysmal subarachnoid hemorrhage (aSAH), and to assess whether miR-1297 was the prognostic indicator of aSAH. Methods: We treated 128 aSAH patients with endovascular coiling. The World Federation of Neurological Surgeons (WFNS) grades, Hunt-Hess grades, and modified Fisher scores were used to assess aSAH severity. Neurologic outcome was assessed using the Modified Rankin Scale (mRS) at 1-year post-aSAH. Serum was taken at various time points (24, 72, and 168 h, and 14 days). Serum samples from aSAH patients and healthy controls were subjected to reverse transcription (RT) quantitative real-time PCR (RT-qPCR). Results: A poor outcome at 1 year was associated with significantly higher levels of miR-1297 value at the four time points, higher WFNS grade, higher Hunt-Hess grade, and higher Fisher score. Serum miR-1297 levels were significantly higher in patients, compared with healthy controls. There were significant correlations of miR-1297 concentrations in serum with severity in aSAH. The AUCs of miR-1297 at the four time points for distinguishing the aSAH patients from healthy controls were 0.80, 0.94, 0.77, and 0.59, respectively. After multivariate logistic regression analysis, only miR-1297 at 24 and 72 h enabled prediction of neurological outcome at 1 year. Conclusion: Serum was an independent predictive factor of poor outcome at 1 year following aSAH. This result supports the use of miR-1297 in aSAH to aid determination of prognosis.

Tenascin-C in brain injuries and edema after subarachnoid hemorrhage: Findings from basic and clinical studies

Subarachnoid hemorrhage (SAH) by a rupture of cerebral aneurysms remains the most devastating cerebrovascular disease. Early brain injury (EBI) is increasingly recognized to be the primary determinant for poor outcomes, and also considered to cause delayed cerebral ischemia (DCI) after SAH. Both clinical and experimental literatures emphasize the impact of global cerebral edema in EBI as negative prognostic and direct pathological factors. The nature of the global cerebral edema is a mixture of cytotoxic and vasogenic edema, both of which may be caused by post-SAH induction of tenascin-C (TNC) that is an inducible, non-structural, secreted and multifunctional matricellular protein. Experimental SAH induces TNC in brain parenchyma in rats and mice. TNC knockout suppressed EBI in terms of brain edema, blood-brain barrier disruption, neuronal apoptosis and neuroinflammation, associated with the inhibition of post-SAH activation of mitogen-activated protein kinases and nuclear factor-kappa B in mice. In a clinical setting, more severe SAH increases more TNC in cerebrospinal fluid and peripheral blood, which could be a surrogate marker of EBI and predict DCI development and outcomes. In addition, cilostazol, a selective inhibitor of phosphodiesterase type III that is a clinically available anti-platelet agent and is known to suppress TNC induction, dose-dependently inhibited delayed cerebral infarction and improved outcomes in a pilot clinical study. Thus, further studies may facilitate application of TNC as biomarkers for non-invasive diagnosis or assessment of EBI and DCI, and lead to development of a molecular target drug against TNC, contributing to the improvement of post-SAH outcomes.

Brain Extracellular Interleukin-6 Levels Decrease Following Antipyretic Therapy with Diclofenac in Patients with Spontaneous Subarachnoid Hemorrhage

In patients with aneurysmal subarachnoid hemorrhage (aSAH), increased brain extracellular interleukin (IL)-6 levels measured by cerebral microdialysis (CMD) were associated with disease severity, early brain injury, delayed cerebral infarction, and axonal injury. In this study, we analyzed brain extracellular IL-6 levels of aSAH patients following parenteral diclofenac. Twenty-four mechanically ventilated poor-grade aSAH patients were included. Changes in cerebral metabolism, brain/body temperature, and CMD-IL-6 levels following intravenous diclofenac infusion (DCF; 75 mg diluted in 100 cc normal saline) were retrospectively analyzed from prospectively collected bedside data (at 1 hour before DCF = baseline; and at 2, 4, and 8 hours after DCF). Statistical analysis was performed using generalized estimating equations. Seventy-two events in 24 aSAH patients were analyzed. Median age was 60 years (interquartile range [IQR]: 52-67), admission Hunt & Hess grade was 4 (IQR: 3-5), and modified Fisher grade (mFisher) was 4 (IQR: 3-4). Higher CMD-IL-6 levels at baseline were linked to fever, higher mFisher, delayed cerebral infarction, and metabolic distress (p < 0.05). CMD-IL-6 levels at baseline were 281.4 pg/mL (IQR: 47-1866) and significantly (p < 0.001; Wald-X² = 106) decreased at 2 hours to 86.3 pg/mL (IQR: 7-1946), at 4 hours to 40.9 pg/mL (IQR: 4-1237), and at 8 hours to 53.5 pg/mL (IQR: 5-1085), independent of probe location or day after bleeding. Parenteral diclofenac may attenuate brain extracellular proinflammatory response in poor-grade aSAH patients.

Cattle Encephalon Glycoside and Ignotin Reduce Early Brain Injury and Cognitive Dysfunction after Subarachnoid Hemorrhage in Rats

Subarachnoid hemorrhage (SAH) is a well-known hemorrhagic stroke with high rates of morbidity and mortality where patients frequently experience cognitive dysfunction. This study explores a potential treatment for cognitive dysfunction following SAH with the demonstration that multi-target drug cattle encephalon glycoside and ignotin (CEGI) can relieve cognitive dysfunction by decreasing hippocampal neuron apoptosis following SAH in rats. Experimentally, 110 male SD rats were separated at random into Sham (20), SAH + Vehicle (30), SAH + 4 ml/kg CEGI (30), and SAH + 1 ml/kg CEGI groups (30) and an endovascular perforation model was created to induce SAH. We discovered that the number of TUNEL-positive neurons in the hippocampus was markedly decreased in SAH + 4 ml/kg and SAH + 1 ml/kg CEGI groups compared to the SAH + Vehicle group. This finding was associated with an observed decrease in Bax/Bcl-2 ratio, cytochrome-c and PUMA expression, and the suppression of caspase-3 activation following SAH. In Morris water maze tests, the SAH + 4 ml/kg CEGI group demonstrated a decreased escape latency time and increase in time spent in the target quadrant as well as crossing times of platform region. These results indicate that high doses of CEGI can decrease hippocampal neuron apoptosis and relieve cognitive dysfunction in rats, suggesting that multitarget-drug CEGI exhibits a neuroprotective effect in SAH via the mitochondrial apoptosis pathway.

Dexmedetomidine attenuated early brain injury in rats with subarachnoid haemorrhage by suppressing the inflammatory response: The TLR4/NF-κB pathway and the NLRP3 inflammasome may be involved in the mechanism

Early brain injury (EBI) plays a pivotal role in the prognosis of patients with subarachnoid haemorrhage (SAH). Dexmedetomidine (DEX), a highly selective α₂ receptor agonist, is reported to exert multiple protective effects in many neurological diseases. This study was designed to investigate whether DEX had neuroprotective functions in EBI after SAH, and to explore the possible mechanisms. The SAH model was established by an endovascular perforation in adult male Sprague-Dawley (SD) rats. DEX (25 µg/kg) or vehicle was administered intraperitoneally 2 h after SAH. Neurological deficits, brain oedema, inflammation, BBB damage, and cell apoptosis at 24 h after SAH were evaluated. Additionally, the expression of components of the Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) pathway, and the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome were also assessed. We demonstrated that DEX treatment improved neurological scores, alleviated brain oedema, reduced the permeability of the blood-brain barrier (BBB), and up-regulated the expression of tight junction proteins. DEX treatment could reduce the neutrophil infiltration, microglial activation, and pro-inflammatory factor release. In addition, DEX alleviated cell apoptosis at 24 h after SAH. Notably, DEX could also suppress the activation of the TLR4/NF-κB pathway and the NLRP3 inflammasome. These findings suggested that treatment with DEX after SAH attenuated SAH-induced EBI, partially through the suppression of the TLR4/NF-κB pathway and the NLRP3 inflammasome.

Noninvasive Neuromonitoring: Current Utility in Subarachnoid Hemorrhage, Traumatic Brain Injury, and Stroke

Noninvasive neuromonitoring is increasingly being used to monitor the course of primary brain injury and limit secondary brain damage of patients in the neurocritical care unit. Proposed advantages over invasive neuromonitoring methods include a lower risk of infection and bleeding, no need for surgical installation, mobility and portability of some devices, and safety. The question, however, is whether noninvasive neuromonitoring is practical and trustworthy enough already. We searched the recent literature and reviewed English-language studies on noninvasive neuromonitoring in subarachnoid hemorrhage, traumatic brain injury, and ischemic and hemorrhagic stroke between the years 2010 and 2015. We found 88 studies that were eligible for review including the methods transcranial ultrasound, electroencephalography, evoked potentials, near-infrared spectroscopy, bispectral index, and pupillometry. Noninvasive neuromonitoring cannot yet completely replace invasive methods in most situations, but has great potential being complementarily integrated into multimodality monitoring, for guiding management, and for limiting the use of invasive devices and in-hospital transports for imaging.

Effect of Early Brain Infarction After Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis

OBJECTIVE

Aneurysmal subarachnoid hemorrhage (aSAH) is an acute cerebrovascular event that leads to devastating consequences. Early brain infarction (EBI) develops very early, within the first 72 hours after bleeding, and may have a significant impact on long-term outcomes. The incidence and impact of EBI in the prognosis of aSAH remain uncertain. We performed a systematic review and meta-analysis to evaluate the incidence of EBI in patients with aSAH and determine its effect on mortality and functional outcomes.

METHODS

We performed a systematic review and meta-analysis. Inclusion criteria were 1) studies that evaluated aSAH within 72 hours after bleeding; 2) performed a brain imaging study up to 72 hours of hemorrhage; 3) used computed tomography or magnetic resonance imaging; and 4) included a description of the findings of the brain imaging study (whether or not an infarct was present).

RESULTS

Ten studies that met the criteria were included. The incidence of EBI was 17%. The risk ratio for 3-month mortality was 2.18 (95% confidence interval 1.48-3.30). The overall risk ratio for poor outcome was 2.26 (95% confidence interval 1.75-2.93).

CONCLUSIONS

EBI plays an important role in the outcome of patients with aSAH. Its significant impact could represent a new therapeutic frontier for improving outcomes of these patients.

Enteral nutrition increases interstitial brain glucose levels in poor-grade subarachnoid hemorrhage patients

Low brain tissue glucose levels after acute brain injury are associated with poor outcome. Whether enteral nutrition (EN) reliably increases cerebral glucose levels remains unclear. In this retrospective analysis of prospectively collected observational data, we investigate the effect of EN on brain metabolism in 17 poor-grade subarachnoid hemorrhage (SAH) patients undergoing cerebral microdialysis (CMD) monitoring. CMD-values were obtained hourly. A nutritional intervention was defined as the clinical routine administration of EN without supplemental parenteral nutrition. Sixty-three interventions were analyzed. The mean amount of EN per intervention was 472.4 ± 10.7 kcal. CMD-glucose levels significantly increased from 1.59 ± 0.13 mmol/l at baseline to a maximum of 2.03 ± 0.2 mmol/l after 5 h (p < 0.001), independently of insulin-treatment, baseline serum glucose, baseline brain metabolic distress (CMD-lactate-to-pyruvate-ratio (LPR) > 40) and the microdialysis probe location. The increase in CMD-glucose was directly dependent on the magnitude of increase of serum glucose levels (p = 0.007). No change in CMD-lactate, CMD-pyruvate, CMD-LPR, or CMD-glutamate (p > 0.4) was observed. Routine EN also increased CMD-glucose even if baseline concentrations were critically low ( < 0.7 mmol/l, neuroglucopenia; p < 0.001). These results may have treatment implications regarding glucose management of poor-grade aneurysmal SAH patients.

Reduction of inflammation after administration of interleukin-1 receptor antagonist following aneurysmal subarachnoid hemorrhage: results of the Subcutaneous Interleukin-1Ra in SAH (SCIL-SAH) study

OBJECTIVE Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating cerebrovascular event with long-term morbidity and mortality. Patients who survive the initial bleeding are likely to suffer further early brain injury arising from a plethora of pathological processes. These may result in a worsening of outcome or death in approximately 25% of patients and may contribute to longer-term cognitive dysfunction in survivors. Inflammation, mediated by the cytokine interleukin-1 (IL-1), is an important contributor to cerebral ischemia after diverse forms of brain injury, including aSAH. Its effects are attenuated by its naturally occurring antagonist, IL-1 receptor antagonist (IL-1Ra [anakinra]). The authors hypothesized that administration of additional subcutaneous IL-1Ra would reduce inflammation and associated plasma markers associated with poor outcome following aSAH. METHODS This was a randomized, open-label, single-blinded study of 100 mg subcutaneous IL-1Ra, administered twice daily in patients with aSAH, starting within 3 days of ictus and continuing until 21 days postictus or discharge from the neurosurgical center, whichever was earlier. Blood samples were taken at admission (baseline) and at Days 3-8, 14, and 21 postictus for measurement of inflammatory markers. The primary outcome was difference in plasma IL-6 measured as area under the curve between Days 3 and 8, corrected for baseline value. Secondary outcome measures included similar area under the curve analyses for other inflammatory markers, plasma pharmacokinetics for IL-1Ra, and clinical outcome at 6 months. RESULTS Interleukin-1Ra significantly reduced levels of IL-6 and C-reactive protein (p < 0.001). Fibrinogen levels were also reduced in the active arm of the study (p < 0.002). Subcutaneous IL-1Ra was safe, well tolerated, and had a predictable plasma pharmacokinetic profile. Although the study was not powered to investigate clinical effect, scores of the Glasgow Outcome Scale-extended at 6 months were better in the active group; however, this outcome did not reach statistical significance. CONCLUSIONS Subcutaneous IL-1Ra is safe and well tolerated in aSAH. It is effective in reducing peripheral inflammation. These data support a Phase III study investigating the effect of IL-1Ra on outcome following aSAH. Clinical trial registration no.: EudraCT: 2011-001855-35 ( www.clinicaltrialsregister.eu ).

Early matrix metalloproteinase-9 concentration in the first 48 h after aneurysmal subarachnoid haemorrhage predicts delayed cerebral ischaemia: An observational study

BACKGROUND

Delayed cerebral ischaemia from vasospasm is an important cause of complications and death after aneurysmal subarachnoid haemorrhage. There is currently no established biomarker for identifying patients at high risk of delayed cerebral ischaemia.

OBJECTIVE

Considering the important role of inflammation in the pathogenesis of delayed cerebral ischaemia, we investigated whether matrix metalloproteinase-9 (MMP-9) may be an efficient biomarker for predicting elayed cerebral ischaemia after subarachnoid haemorrhage.

DESIGN

Single-centre prospective observational study.

SETTING

Neuroscience Critical Care Unit of a teaching hospital.

PARTICIPANTS

Thirty consecutive patients with severe subarachnoid haemorrhage requiring external ventricular drainage were enrolled during 2013 and 2014.

INTERVENTIONS

Blood and cerebrospinal fluid (CSF) were sampled within the first 24 h and between 48 and 72 h after admission. We evaluated the activity and concentrations of MMP-9 and endothelin-1 with zymography and ELISA. Patients were allocated to groups with delayed cerebral ischaemia (n = 16) or without delayed cerebral ischaemia (n = 14).

RESULTS

Within 24 h, median [interquartile range] MMP-9 concentrations in CSF were significantly higher in patients with delayed cerebral ischaemia (47 [21 to 102] ng ml) than in those without delayed cerebral ischaemia (4 [2 to 13] ng ml, P = 0.001). CSF MMP-9 activity and endothelin-1 concentrations were correlated (r = 0.6, P = 0.02). The areas under the receiver operating characteristic curves were 0.73 (95% confidence interval [0.53 to 0.87]) and 0.91 (95% confidence interval [0.75 to 0.98]) for MMP-9 concentrations in plasma and CSF, respectively, at 24 h to predict delayed cerebral ischaemia CSF MMP-9 concentrations more than 14.3 ng ml at 24 h predicted the occurrence of delayed cerebral ischaemia with a sensitivity and specificity of 88 and 86%, respectively. After multivariate logistic analysis, only CSF MMP-9 concentrations at 24 h predicted the occurrence of delayed cerebral ischaemia (P = 0.01).

CONCLUSION

MMP-9 concentrations in both plasma and CSF, measured within 48 h after subarachnoid haemorrhage, were highly predictive of the occurrence of delayed cerebral ischaemia within the first 2 weeks.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02397759.

Potential implications of Apolipoprotein E in early brain injury after experimental subarachnoid hemorrhage: Involvement in the modulation of blood-brain barrier integrity

Apolipoprotein E (Apoe) genetic polymorphisms have been implicated in the long term outcome of subarachnoid haemorrhage (SAH), but little is known about the effect of Apoe on the early brain injury (EBI) after SAH. This study investigated the potential role of APOE in EBI post-SAH. Multiple techniques were used to determine the early BBB disruption in EBI post-SAH in a murine model using wild-type (WT) and Apoe^−/− (KO) mice. Progressive BBB disruption (Evans blue extravasation and T2 hyperintensity in magnetic resonance imaging) was observed before the peak of endogenous APOE expression elevation at 48h after SAH. Moreover, Apoe^−/− mice exhibited more severe BBB disruption charcteristics after SAH than WT mice, including higher levels of Evans blue and IgG extravasation, T2 hyperintensity in magnetic resonance imaging, tight junction proteins degradation and endothelial cells death. Mechanistically, we found that APOE restores the BBB integrity in the acute stage after SAH via the cyclophilin A (CypA)-NF-κB-proinflammatory cytokines-MMP-9 signalling pathway. Consequently, although early BBB disruption causes neurological dysfunctions after SAH, we capture a different aspect of the effects of APOE on EBI after SAH that previous studies had overlooked and open up the idea of BBB disruption as a target of APOE-based therapy for EBI amelioration research in the future.

Intraventricular Hemorrhage Caused by Subarachnoid Hemorrhage: Does the Severity Matter?

OBJECTIVE

Aneurysm rupture might be accompanied by intraventricular hemorrhage (IVH), which is associated with poor outcome of subarachnoid hemorrhage (SAH). The aim of this study was to analyze risk factors and clinical impact of IVH severity.

METHODS

A total of 995 consecutive patients with SAH treated at our institution between January 2003 and June 2016 were eligible for this study. Clinical and radiologic findings were correlated with the presence and severity of IVH assessed with the original Graeb score.

RESULTS

A total of 487 patients with SAH (48.9%) presented with IVH (mean IVH severity, 5.48 points [±3.5]). IVH severity correlated with poorer initial clinical condition (World Federation of Neurosurgical Societies grade >3; P < 0.001), acute hydrocephalus (P = 0.001), and poor outcome at 6 months (modified Rankin Scale score >2; P < 0.001). The location of the ruptured aneurysm in the anterior cerebral artery independently predicted the occurrence (P = 0.007) and severity of IVH (P < 0.001). In turn, aneurysm size affected only the severity of IVH (P = 0.001) but not its occurrence (P = 0.153). Early complications of SAH occurring within 72 hours after the bleeding event (cerebral infarction [P = 0.043], early mortality [P = 0.001], and primary craniectomy [P = 0.043]) were independently associated with the severity of IVH.

CONCLUSIONS

Severity of aneurysmal IVH is a strong contributor to initial severity and early complications of SAH. Patients with larger aneurysms, especially located in the anterior cerebral artery, are at particular risk of severe IVH in cases of aneurysm rupture.

Elevated Systemic IL-6 Levels in Patients with Aneurysmal Subarachnoid Hemorrhage Is an Unspecific Marker for Post-SAH Complications

Background: Aneurysmal subarachnoid hemorrhage (aSAH) is still a fatal and morbid disease, although bleeding aneurysms can be secured in almost all cases. Occurrence of post-SAH complications including cerebral vasospasm, delayed cerebral ischemia, hydrocephalus, epilepsy, and infections are the main determinants of clinical outcome. Hence, it is important to search for early predictors for specific post-SAH complications to treat these complications properly. Both cellular and molecular (cytokines) inflammation play a key role after aSAH during the phase of occurrence of post-SAH complications. Interleukin-6 (IL-6) is a well-known cytokine that has been extensively analyzed in cerebrospinal fluid (CSF) of patients after aSAH, but detailed studies exploring the role of systemic IL-6 in aSAH associated complications and its impact on early clinical outcome prediction are lacking. The current study aims to analyze the systemic IL-6 levels over two weeks after bleeding and its role in post-SAH complications. Methods: We recruited 80 aSAH patients prospectively who underwent peripheral venous blood withdrawal in serum gel tubes. The blood was centrifuged to harvest the serum, which was immediately frozen at −80 °C until analysis. Serum IL-6 levels were quantified using Immulite immunoassay system. Patient records including age, gender, post-SAH complications, aneurysm treatment, and clinical outcome (modified Rankin scale and Glasgow outcome scale) were retrieved to allow different subgroup analysis. Results: Serum IL-6 levels were significantly raised after aSAH compared to healthy controls over the first two weeks after hemorrhage. Serum IL-6 levels were found to be significantly elevated in aSAH patients presenting with higher Hunt and Hess grades, increasing age, and both intraventricular and intracerebral hemorrhage. Interestingly, serum IL-6 was also significantly raised in aSAH patients who developed seizures, cerebral vasospasm (CVS), and chronic hydrocephalus. IL-6 levels were sensitive to the development of infections and showed an increase in patients who developed pneumoniae. Intriguingly, we found a delayed increase in serum IL-6 in patients developing cerebral infarction. Finally, IL-6 levels were significantly higher in patients presenting with poor clinical outcome in comparison to good clinical outcome at discharge from hospital. Conclusion: Serum IL-6 levels were elevated early after aSAH and remained high over the two weeks after initial bleeding. Serum IL-6 was elevated in different aSAH associated complications, acting as a non-specific marker for post-SAH complications and an important biomarker for clinical outcome at discharge.

Peli1 Contributions in Microglial Activation, Neuroinflammatory Responses and Neurological Deficits Following Experimental Subarachnoid Hemorrhage

Early brain injury (EBI) following subarachnoid hemorrhage (SAH) is closely associated with neuroinflammation. Microglial activation is an early event that leads to neuroinflammation after SAH. Peli1 is an E3 ubiquitin ligase that mediates the induction of pro-inflammatory cytokines in microglia. Here we report Peli1 contributions in SAH mediated brain pathology. An SAH model was induced by endovascular perforation in adult male C57BL/6J mice. Peli1 was markedly induced in mice brains in a time-dependent manner and was predominantly expressed in CD16/32-positive microglia after SAH. Using genetic approaches, we demonstrated that decreased Peli1 significantly improved neurological deficits, attenuated brain edema, reduced over-expression of pro-inflammatory cytokine IL-6 and modified apoptotic/antiapoptotic biomarkers. In addition, Peli1 downregulation suppressed ERK and JNK phosphorylation levels via the downregulation of cIAP1/2 expression, subsequently reducing inducible nitric oxide synthase (iNOS) expression after SAH. Therefore, these findings demonstrate that Peli1 contributes to microglia-mediated neuroinflammation in EBI by mediating cIAP1/2 activation, thus promoting the activation of MyD88-dependent MAPK pathway after experimental SAH. Our findings also showed that Peli1 could promote the expression of M1 microglia polarization biomarker CD16/32 and iNOS after SAH. Targeting Peli1 exerts neuroprotective effects during EBI after SAH, thus could provide potential option for prevention-therapy in high-risk individuals.

Cerebral Microdialysis Monitoring to Improve Individualized Neurointensive Care Therapy: An Update of Recent Clinical Data

Cerebral microdialysis (CMD) allows bedside semicontinuous monitoring of patient brain extracellular fluid. Clinical indications of CMD monitoring are focused on the management of secondary cerebral and systemic insults in acute brain injury (ABI) patients [mainly, traumatic brain injury (TBI), subarachnoid hemorrhage, and intracerebral hemorrhage (ICH)], specifically to tailor several routine interventions—such as optimization of cerebral perfusion pressure, blood transfusion, glycemic control and oxygen therapy—in the individual patient. Using CMD as clinical research tool has greatly contributed to identify and better understand important post-injury mechanisms—such as energy dysfunction, posttraumatic glycolysis, post-aneurysmal early brain injury, cortical spreading depressions, and subclinical seizures. Main CMD metabolites (namely, lactate/pyruvate ratio, and glucose) can be used to monitor the brain response to specific interventions, to assess the extent of injury, and to inform about prognosis. Recent consensus statements have provided guidelines and recommendations for CMD monitoring in neurocritical care. Here, we summarize recent clinical investigation conducted in ABI patients, specifically focusing on the role of CMD to guide individualized intensive care therapy and to improve our understanding of the complex disease mechanisms occurring in the immediate phase following ABI. Promising brain biomarkers will also be described.

Clinical Use of Cerebral Microdialysis in Patients with Aneurysmal Subarachnoid Hemorrhage-State of the Art

Objective

To review the published literature on the clinical application of cerebral microdialysis (CMD) in aneurysmal subarachnoid hemorrhage (SAH) patients and to summarize the evidence relating cerebral metabolism to pathophysiology, secondary brain injury, and outcome.

Methods

Study selection: Two reviewers identified all manuscripts reporting on the clinical use of CMD in aneurysmal SAH patients from MEDLINE. All identified studies were grouped according to their focus on brain metabolic changes during the early and subacute phase after SAH, their association with mechanisms of secondary brain injury and outcome.

Results

The review demonstrated: (1) limited literature is available in the very early phase before the aneurysm is secured. (2) Brain metabolic changes related to early and delayed secondary injury mechanisms may be used in addition to other neuromonitoring parameters in the critical care management of SAH patients. (3) CMD markers of ischemia may detect delayed cerebral ischemia early (up to 16 h before onset), underlining the importance of trend analysis. (4) Various CMD-derived parameters may be associated with patient outcome at 3–12 months, including CMD-lactate-to-pyruvate-ratio, CMD-glucose, and CMD-glutamate.

Conclusion

The clinical use of CMD is an emerging area in the literature of aneurysmal SAH patients. Larger prospective multi-center studies on interventions based on CMD findings are needed.

Amino Acids in Cerebrospinal Fluid of Patients with Aneurysmal Subarachnoid Haemorrhage: An Observational Study

Background

The authors are aware of only one article investigating amino acid concentrations in cerebrospinal fluid (CSF) in patients with ruptured intracranial aneurysms, and this was published 31 years ago. Since then, both management of subarachnoid haemorrhage (SAH) and amino acid assay techniques have seen radical alterations, yet the pathophysiology of SAH remains unclear.

Objective

To analyse the pattern of concentrations of amino acids and related compounds in patients with different outcomes following aneurysmal SAH.

Methods

49 CSF samples were collected from 23 patients on days 0–3, 5, and 10 post-SAH. Concentrations of 33 amino acids and related compounds were assayed by liquid chromatography tandem mass spectrometry in patients with good [Glasgow Outcome Scale (GOS) 1–3] and poor (GOS 4–5) outcome.

Results

Of the 33 compounds assayed, only hydroxyproline and 3-aminoisobutyric acid appeared not to increase significantly following SAH. In poor outcome patients, we found significantly higher concentrations of aspartic acid (p = 0.038), glutamic acid (p = 0.038), and seven other compounds on days 0–3 post-SAH; glutamic acid (p = 0.041) on day 5 post-SAH, and 2-aminoadipic acid (p = 0.033) on day 10 post-SAH. The most significant correlation with GOS at 3 months was found for aminoadipic acid on day 10 post-SAH (cc = −0.81).

Conclusion

Aneurysmal rupture leads to a generalised increase of amino acids and related compounds in CSF. The patterns differ between good and poor outcome cases. Increased excitatory amino acids are strongly indicative of poor outcome.

Cerebrospinal Fluid and Microdialysis Cytokines in Aneurysmal Subarachnoid Hemorrhage: A Scoping Systematic Review

Objective

To perform two scoping systematic reviews of the literature on cytokine measurement in cerebral microdialysis (CMD) and cerebrospinal fluid (CSF) in aneurysmal subarachnoid hemorrhage (SAH) patients, aiming to summarize the evidence relating cytokine levels to pathophysiology, disease progression, and outcome.

Methods

Two separate systematic reviews were conducted: one for CMD cytokines and the second for CSF cytokines.

Data sources

Articles from MEDLINE, BIOSIS, EMBASE, Global Health, Scopus, Cochrane Library (inception to October 2016), reference lists of relevant articles, and gray literature were searched.

Study selection

Two reviewers independently identified all manuscripts utilizing predefined inclusion/exclusion criteria. A two-tier filter of references was conducted.

Data extraction

Patient demographic and study data were extracted to tables.

Results

There were 9 studies identified describing the analysis of cytokines via CMD in 246 aneurysmal SAH patients. Similarly, 20 studies were identified describing the analysis of CSF cytokines in 630 patients. The two scoping systematic reviews demonstrated the following: (1) limited literature available on CMD cytokine measurement in aneurysmal SAH with some preliminary data supporting feasibility of measurement and potential association between interleukin (IL)-6 and patient outcome. (2) Various CSF measured cytokines may be associated with patient outcome at 3–6 months, including IL-1ra, IL-6, IL-8, and tumor necrosis factor-alpha. (3) There is a small literature body supporting an association between acute/subacute CSF transforming growth factor levels and the development of chronic hydrocephalus at 2–3 months.

Conclusion

The evaluation of CMD and CSF cytokines is an emerging area of the literature in aneurysmal SAH. Further large prospective multicenter studies on cytokines in CMD and CSF need to be conducted.

Serum microRNAs are non-invasive biomarkers for the presence and progression of subarachnoid haemorrhage

miRNAs are important regulators of translation and have been associated with the pathogenesis of a number of cardiovascular diseases including stroke and may be possible prognostic biomarkers. The purpose of the present study was to determine the expression levels of miRNAs in the sera of subarachnoid haemorrhage (SAH) patients and to evaluate their relationships with the severity and clinical outcome of SAH. Serum samples on day 3 after the onset of SAH were subjected to microarray analysis with Exqion miRCURY^TM LNA array and quantitative PCR analysis. Serum samples from SAH patients (n=60) and healthy controls (n=10) were subjected to quantitative PCR analysis. The severities and clinical outcomes of the SAH patients were evaluated with the WFNS grade and the Modified Rankin Scale (mRS). Three miRNAs, miR-502-5p, miR-1297 and miR-4320 were significantly up-regulated in the sera of SAH patients when compared with the healthy controls. The serum miR-502-5p and miR-1297 levels were significantly higher in the patients with severe SAH and a poor outcome than in those with mild SAH and a good outcome (P<0.05). The areas under the receiver operating characteristic (ROC) curves (AUCs) of miR-502-5p, miR-1297 and miR-4320 to distinguish the SAH patients from the healthy controls were 0.958 (P<0.001), 0.950 (P<0.001) and 0.843 (P<0.001) respectively. Taken together, these results indicate that miR-502-5p and miR-1297 are potentially valuable indicators of the diagnosis, severity and prognosis of SAH, and miR-4320 was a potentially valuable indicator of the diagnosis of SAH.

The Pathophysiology of Delayed Cerebral Ischemia

Subarachnoid hemorrhage (SAH) affects 30,000 people in the Unites States alone each year. Delayed cerebral ischemia occurs days after subarachnoid hemorrhage and represents a potentially treatable cause of morbidity for approximately one-third of those who survive the initial hemorrhage. While vasospasm has been traditionally linked to the development of cerebral ischemia several days after subarachnoid hemorrhage, emerging evidence reveals that delayed cerebral ischemia is part of a much more complicated post-subarachnoid hemorrhage syndrome. The development of delayed cerebral ischemia involves early arteriolar vasospasm with microthrombosis, perfusion mismatch and neurovascular uncoupling, spreading depolarizations, and inflammatory responses that begin at the time of the hemorrhage and evolve over time, culminating in cortical infarction. Large-vessel vasospasm is likely a late contributor to ongoing injury, and effective treatment for delayed cerebral ischemia will require improved detection of critical early pathophysiologic changes as well as therapeutic options that target multiple related pathways.

Brain Monitoring in Critically Neurologically Impaired Patients

Assessment of neurologic injury and the evolution of severe neurologic injury is limited in comatose or critically ill patients that lack a reliable neurologic examination. For common yet severe pathologies such as the comatose state after cardiac arrest, aneurysmal subarachnoid hemorrhage (aSAH), and severe traumatic brain injury (TBI), critical medical decisions are made on the basis of the neurologic injury. Decisions regarding active intensive care management, need for neurosurgical intervention, and withdrawal of care, depend on a reliable, high-quality assessment of the true state of neurologic injury, and have traditionally relied on limited assessments such as intracranial pressure monitoring and electroencephalogram. However, even within TBI there exists a spectrum of disease that is likely not captured by such limited monitoring and thus a more directed effort towards obtaining a more robust biophysical signature of the individual patient must be undertaken. In this review, multimodal monitoring including the most promising serum markers of neuronal injury, cerebral microdialysis, brain tissue oxygenation, and pressure reactivity index to access brain microenvironment will be discussed with their utility among specific pathologies that may help determine a more complete picture of the neurologic injury state for active intensive care management and long-term outcomes. Goal-directed therapy guided by a multi-modality approach appears to be superior to standard intracranial pressure (ICP) guided therapy and should be explored further across multiple pathologies. Future directions including the application of optogenetics to evaluate brain injury and recovery and even as an adjunct monitoring modality will also be discussed.

SIRT3 Expression Decreases with Reactive Oxygen Species Generation in Rat Cortical Neurons during Early Brain Injury Induced by Experimental Subarachnoid Hemorrhage

Sirtuin3 (SIRT3) is an important protein deacetylase which predominantly presents in mitochondria and exhibits broad bioactivities including regulating energy metabolism and counteracting inflammatory effect. Since inflammatory cascade was proved to be critical for pathological damage following subarachnoid hemorrhage (SAH), we investigated the overall expression and cell-specific distribution of SIRT3 in the cerebral cortex of Sprague-Dawley rats with experimental SAH induced by internal carotid perforation. Results suggested that SIRT3 was expressed abundantly in neurons and endothelia but rarely in gliocytes in normal cerebral cortex. After experimental SAH, mRNA and protein expressions of SIRT3 decreased significantly as early as 8 hours and dropped to the minimum value at 24 h after SAH. By contrast, SOD2 expression increased slowly as early as 12 hours after experimental SAH, rose up sharply at the following 12 hours, and then was maintained at a higher level. In conclusion, attenuated SIRT3 expression in cortical neurons was associated closely with enhanced reactive oxygen species generation and cellular apoptosis, implying that SIRT3 might play an important neuroprotective role during early brain injury following SAH.

Pentoxifylline Alleviates Early Brain Injury After Experimental Subarachnoid Hemorrhage in Rats: Possibly via Inhibiting TLR 4/NF-κB Signaling Pathway

Early brain injury (EBI) after subarachnoid hemorrhage (SAH) generally causes significant and lasting damage. Pentoxifylline (PTX), a nonselective phosphodiesterase inhibitor, has shown anti-inflammatory and neuroprotective properties in several brain injury models, but the role of PTX with respect to EBI following SAH remains uncertain. The purpose of this study was to investigate the effects of PTX on EBI after SAH in rats. Adult male Sprauge-Dawley rats were randomly assigned to the sham and SAH groups. PTX (30 or 60 mg/kg) or an equal volume of the administration vehicle (normal saline) was administrated at 30 min intervals following SAH. Neurological scores, brain edema, and neural cell apoptosis were evaluated. In order to explore other mechanisms, changes in the toll-like receptor 4 (TLR4) and the nuclear factor-κB (NF-κB) signaling pathway, in terms of the levels of apoptosis-associated proteins, were also investigated. We found that administration of PTX (60 mg/kg) notably improved neurological function and decreased brain edema at both 24 and 72 h following SAH. Treatment with PTX (60 mg/kg) significantly inhibited the protein expressions of TLR4, NF-κB, MyD88 and the downstream pro-inflammatory cytokines, such as the tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). PTX also significantly reduced neural cell death and BBB permeability. Our observations may be the first time that PTX has been shown to play a neuroprotective role in EBI after SAH, potentially by suppressing the TLR4/NF-κB inflammation-related pathway in the rat brain.

PARP inhibition attenuates early brain injury through NF-κB/MMP-9 pathway in a rat model of subarachnoid hemorrhage

Poly (ADP-ribose) polymerases (PARPs) play an important role in a range of neurological disorders, however, the role of PARP in early brain injury after subarachnoid hemorrhage (SAH) remains unclear. This study was designed to explore the role and the potential mechanisms of PARP in early brain injury after SAH. Eighty-nine male SD rats were randomly divided into the Sham group, SAH+Vehicle group and SAH+PARP inhibitor (PJ34) group. An endovascular perforation model was used to induce SAH in rats. PJ34 (10mg/kg) or vehicle (0.9% NaCl) was intraperitoneally administered at 5min and 8h after SAH induction. Mortality, SAH grades, neurological function, evans blue extravasation, brain edema, immunofluorescence staining and western blotting were performed. PJ34 reduced BBB permeability and brain edema, improved neurological function and attenuated neuronal cell death in the rat model of SAH. Moreover, PJ34 inhibited the nuclear translocation of NF-κB, decreased the expression of the proinflammatory cytokines IL-1ß, IL-6 and TNF-α, reduced the expression of MMP-9, prevented the degradation of tight junction proteins, and decreased microglia activation. These data indicated that PARP inhibition through PJ34 might be an important therapeutic drug for SAH.

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.

SPIRIT: Systematic Planning of Intelligent Reuse of Integrated Clinical Routine Data. A Conceptual Best-practice Framework and Procedure Model

BACKGROUND

Secondary use of clinical routine data is receiving an increasing amount of attention in biomedicine and healthcare. However, building and analysing integrated clinical routine data repositories are nontrivial, challenging tasks. As in most evolving fields, recognized standards, well-proven methodological frameworks, or accurately described best-practice approaches for the systematic planning of solutions for secondary use of routine medical record data are missing.

OBJECTIVE

We propose a conceptual best-practice framework and procedure model for the systematic planning of intelligent reuse of integrated clinical routine data (SPIRIT).

METHODS

SPIRIT was developed based on a broad literature overview and further refined in two case studies with different kinds of clinical routine data, including process-oriented nursing data from a large hospital group and high-volume multimodal clinical data from a neurologic intensive care unit.

RESULTS

SPIRIT aims at tailoring secondary use solutions to specific needs of single departments without losing sight of the institution as a whole. It provides a general conceptual best-practice framework consisting of three parts: First, a secondary use strategy for the whole organization is determined. Second, comprehensive analyses are conducted from two different viewpoints to define the requirements regarding a clinical routine data reuse solution at the system level from the data perspective (BOTTOM UP) and at the strategic level from the future users perspective (TOP DOWN). An obligatory clinical context analysis (IN BETWEEN) facilitates refinement, combination, and integration of the different requirements. The third part of SPIRIT is dedicated to implementation, which comprises design and realization of clinical data integration and management as well as data analysis solutions.

CONCLUSIONS

The SPIRIT framework is intended to be used to systematically plan the intelligent reuse of clinical routine data for multiple purposes, which often was not intended when the primary clinical documentation systems were implemented. SPIRIT helps to overcome this gap. It can be applied in healthcare institutions of any size or specialization and allows a stepwise setup and evolution of holistic clinical routine data reuse solutions.

Association of early inflammatory parameters after subarachnoid hemorrhage with functional outcome: A prospective cohort study

OBJECTIVE

Early brain injury after aneurysmal subarachnoid hemorrhage (aSAH) comprises a pronounced neuroinflammatory reaction. Nevertheless, its relevance for functional outcome and its role as outcome predictor remains uncertain. We evaluated the relationship of various early inflammatory parameters regarding functional outcome according to the modified Rankin Scale score (mRS) at discharge (primary objective) and six months after aSAH.

PATIENTS

A total of 81 patients (63% female) with a mean age of 53.8 ± 13.2 years were included.

METHODS

At admission clinical data and various inflammatory parameters in serum and - wherever applicable - cerebrospinal fluid (CSF) of patients after aSAH were assessed. Outcome was evaluated according to dichotomized mRS at discharge and six months after aSAH (unfavorable outcome: mRS 3-6). Univariate and thereafter multivariate logistic regression analyses were performed using SAS 9.2.

RESULTS

Elevated levels of interleukin 6 (IL-6) and leukemia inhibitory factor (LIF) in serum and CSF were related to unfavorable outcome at discharge (p<0.05; univariate analyses). IL-6 remains the only parameter relevant for outcome applying a multivariate model including the relevant baseline characteristics. Six months after aSAH no significant correlation was found regarding the outcome, most likely due to the high drop-out rate (27%). A pronounced rise of LIF serum and CSF levels after aSAH was observed.

CONCLUSION

Higher early IL-6 serum levels after aSAH are associated with poor outcome at discharge. In addition, involvement of LIF in the early inflammatory reaction after aSAH has been demonstrated.

Hyperbaric oxygen therapy ameliorates acute brain injury after porcine intracerebral hemorrhage at high altitude

Introduction

Intracerebral hemorrhage (ICH) at high altitude is not well understood to date. This study investigates the effects of high altitude on ICH, and examines the acute neuroprotection of hyperbaric oxygen (HBO) therapy against high-altitude ICH.

Methods

Minipigs were placed in a hypobaric chamber for 72 h before the operation. ICH was induced by an infusion of autologous arterial blood (3 ml) into the right basal ganglia. Animals in the high-altitude ICH group received HBO therapy (2.5 ATA for 60 min) 30 min after ICH. Blood gas, blood glucose and brain tissue oxygen partial pressure (PbtO₂) were monitored continuously for animals from all groups, as were microdialysis products including glucose, lactate, pyruvate and glutamate in perihematomal tissue from 3 to 12 h post-ICH.

Results

High-altitude ICH animals showed significantly lower PbtO₂, higher lactate/pyruvate ratio (LPR) and glutamate levels than low-altitude ICH animals. More severe neurological deficits, brain edema and neuronal damage were also observed in high-altitude ICH. After HBO therapy, PbtO₂ was significantly increased and LPR and glutamate levels were significantly decreased. Brain edema, neurological deficits and neuronal damage were also ameliorated.

Conclusions

The data suggested a more serious disturbance of tissue oxygenation and cerebral metabolism in the acute stage after ICH at high altitude. Early HBO treatment reduced acute brain injury, perhaps through a mechanism involving the amelioration of the derangement of cerebral oxygenation and metabolism following high-altitude ICH.