Global cerebral edema after subarachnoid hemorrhage: frequency, predictors, and impact on outcome

Mortality after Spontaneous Subarachnoid Hemorrhage: Causality and Validation of a Prediction Model

OBJECTIVE

To evaluate primary causes of death after spontaneous subarachnoid hemorrhage (SAH) and externally validate the HAIR score, a prognostication tool, in a single academic institution.

METHODS

We reviewed all patients with SAH admitted to our neuro-intensive care unit between 2010 and 2016. Univariate and multivariate logistic regressions were performed to identify predictors of in-hospital mortality. The HAIR score predictors were Hunt and Hess grade at treatment decision, age, intraventricular hemorrhage, and rebleeding within 24 hours. Validation of the HAIR score was characterized with the receiver operating curve, the area under the curve, and a calibration plot.

RESULTS

Among 434 patients with SAH, in-hospital mortality was 14.1%. Of the 61 mortalities, 54 (88.5%) had a neurologic cause of death or withdrawal of care and 7 (11.5%) had cardiac death. Median time from SAH to death was 6 days. The main causes of death were effect of the initial hemorrhage (26.2%), rebleeding (23%) and refractory cerebral edema (19.7%). Factors significantly associated with in-hospital mortality in the multivariate analysis were age, Hunt and Hess grade, and intracerebral hemorrhage. Maximum lumen size was also a significant risk factor after aneurysmal SAH. The HAIR score had a satisfactory discriminative ability, with an area under the curve of 0.89.

CONCLUSIONS

The in-hospital mortality is lower than in previous reports, attesting to the continuing improvement of our institutional SAH care. The major causes are the same as in previous reports. Despite a different therapeutic protocol, the HAIR score showed good discrimination and could be a useful tool for predicting mortality.

Levels of Interleukin-1β, Interleukin-18, and Tumor Necrosis Factor-α in Cerebrospinal Fluid of Aneurysmal Subarachnoid Hemorrhage Patients May Be Predictors of Early Brain Injury and Clinical Prognosis

BACKGROUND

Aneurysmal subarachnoid hemorrhage (aSAH) is a severe cerebrovascular accident with high morbidity and mortality. The aim of this study is to investigate the relationship between level of inflammatory cytokines in cerebrospinal fluid (CSF) of aSAH patients, the severity of aSAH, and the outcome of aSAH patients.

METHODS

aSAH patients were prospectively included and followed-up for 6 months. CSF samples were collected at 1-3, 4-6, and 7-9 days after aSAH onset. Levels of interleukin (IL)-1β, IL-18, and tumor necrosis factor-α (TNF-α) in the CSF of aSAH patients were measured by enzyme-linked immunosorbent assay.

RESULTS

Eighty-one aSAH patients were enrolled. The levels of IL-1β, IL-18 and TNF-α in the CSF were especially higher in the group of aSAH patients with cerebral edema, cerebral vasospasm, and a high grade on Hunt-Hess scale, the high World Federation of Neurological Surgeons grades, and Fisher grade (P < 0.01). Higher levels of plasma C-reactive protein in the blood were correlated with poor outcome. The areas under the receiver operating characteristic curves for the levels of inflammatory cytokines in CSF were 0.85, 0.84, and 0.95, respectively. Clinical features (age, Hunt-Hess grade, etc.) were positively correlated with poor outcomes (P < 0.05).

CONCLUSIONS

The levels of IL-1β, IL-18, and TNF-α in CSF were elevated in aSAH patients and were positively associated with cerebral edema and acute hydrocephalus. Our findings suggest that CSF inflammatory cytokines might be biomarkers to assess severity and predict outcomes.

Hunt-Hess 5 subarachnoid haemorrhage presenting with cardiac arrest is associated with larger volume bleeds

AIMS

The mechanism, effects, and outcomes of cardiac arrest (CA) caused by subarachnoid haemorrhage (SAH) remain unclear. We compared SAH patients presenting with CA to other high-grade SAH patients presenting without CA in order to better understand (1) the cause of CA, (2) cerebral pathophysiology following CA, and (3) outcomes of CA in patients with SAH.

METHODS

We performed a retrospective analysis of a prospectively collected observational cohort. 31 Hunt-Hess 5 patients that presented with CA were compared to 146 Hunt-Hess 5 patients that presented without CA. Clinical and imaging findings were predefined and adjudicated. Cerebral physiology measures were available for a subset of patients, matched 1:1 by age.

RESULTS

Twenty-two (71%) CA patients had pulseless electrical activity/asystole compared to 2 (6%) with a shockable rhythm. The CA patients were younger (OR 0.96, 95% CI 0.93-0.99, p=0.009), had more SAH on CT (OR 1.07, 95% CI 1.01-1.13, p=0.02), and had higher in-hospital mortality (87% vs. 58%, OR 6.2 (2.1-26.6), p=0.004). There were no differences in aneurysm location, cerebral herniation, or ictal seizures. Despite similar cerebral perfusion pressure, CA patients had pathologically lower brain tissue oxygenation, lower glucose, and higher lactate to pyruvate ratios.

CONCLUSIONS

CA in SAH is associated with larger volume bleeds. Despite normal cerebral perfusion pressures, CA patients show compromised cerebral physiology.

Mechanisms of Global Cerebral Edema Formation in Aneurysmal Subarachnoid Hemorrhage

A growing body of clinical literature emphasizes the impact of cerebral edema in early brain injury following aneurysmal subarachnoid hemorrhage (aSAH). Aneurysm rupture itself initiates global cerebral edema in up to two thirds of cases. Although cerebral edema is not a universal feature of aSAH, it portends a poor clinical course, with quantitative analysis revealing a direct correlation between cerebral edema and poor outcome, including mortality and cognitive deficits. Mechanistically, global cerebral edema has been linked to global ischemia at the time of aneurysm rupture, dysfunction of autoregulation, blood breakdown products, neuroinflammation, and hyponatremia/endocrine abnormalities. At a molecular level, several culprits have been identified, including aquaporin-4, matrix metalloproteinase-9, SUR1-TRPM4 cation channels, vascular endothelial growth factor, bradykinin, and others. Here, we review these cellular and molecular mechanisms of global cerebral edema formation in aSAH. Given the importance of edema to the outcome of patients with aSAH and its status as a highly modifiable pathological process, a better understanding of cerebral edema in aSAH promises to hasten the development of medical therapies to improve outcomes in this frequently devastating disease.

Minocycline protects against delayed cerebral ischemia after subarachnoid hemorrhage via matrix metalloproteinase-9 inhibition

Objective

Delayed cerebral ischemia (DCI) is an independent risk factor for poor outcome after aneurysmal subarachnoid hemorrhage (SAH) and is multifactorial in etiology. While prior studies have suggested a role for matrix metalloproteinase-9 (MMP-9) in early brain injury after SAH, its contribution to the pathophysiology of DCI is unclear.

Methods

In the first experiment, wild-type (WT) and MMP-9^-/- mice were subjected to sham or endovascular perforation SAH surgery. In separate experiments, WT and MMP-9^-/-mice were administered vehicle or minocycline either pre- or post-SAH. All mice underwent assessment of multiple components of DCI including vasospasm, neurobehavioral function, and microvessel thrombosis. In another experiment, rabbits were subjected to sham or cisterna magna injection SAH surgery, and administered vehicle or minocycline followed by vasospasm assessment.

Results

MMP-9 expression and activity was increased after SAH. Genetic (MMP-9^-/- mice) and pharmacological (pre-SAH minocycline administration) inhibition of MMP-9 resulted in decreased vasospasm and neurobehavioral deficits. A therapeutically feasible strategy of post-SAH administration of minocycline resulted in attenuation of multiple components of DCI. Minocycline administration to MMP-9^-/- mice did not yield additional protection. Consistent with experiments in mice, both pre- and post-SAH administration of minocycline attenuated SAH-induced vasospasm in rabbits.

Interpretation

MMP-9 is a key player in the pathogenesis of DCI. The consistent attenuation of multiple components of DCI with both pre- and post-SAH administration of minocycline across different species and experimental models of SAH, combined with the excellent safety profile of minocycline in humans suggest that a clinical trial in SAH patients is warranted.

Controlled Hypercapnia Enhances Cerebral Blood Flow and Brain Tissue Oxygenation After Aneurysmal Subarachnoid Hemorrhage: Results of a Phase 1 Study

BACKGROUND

This study investigated if cerebral blood flow (CBF) regulation by changes of the arterial partial pressure of carbon dioxide (PaCO2) can be used therapeutically to increase CBF and improve neurological outcome after subarachnoid hemorrhage (SAH).

METHODS

In 12 mechanically ventilated poor-grade SAH-patients, a daily trial intervention was performed between day 4 and 14. During this intervention, PaCO2 was decreased to 30 mmHg and then gradually increased to 40, 50, and 60 mmHg in 15-min intervals by modifications of the respiratory minute volume. CBF and brain tissue oxygen saturation (StiO2) were the primary and secondary endpoints. Intracranial pressure was controlled by an external ventricular drainage.

RESULTS

CBF reproducibly decreased during hyperventilation and increased to a maximum of 141 ± 53 % of baseline during hypercapnia (PaCO2 60 mmHg) on all days between day 4 and 14 after SAH. Similarly, StiO2 increased during hypercapnia. CBF remained elevated within the first hour after resetting ventilation to baseline parameters and no rebound effect was observed within this time-span. PaCO2-reactivities of CBF and StiO2 were highest between 30 and 50 mmHg and slightly decreased at higher levels.

CONCLUSION

CBF and StiO2 reproducibly increased by controlled hypercapnia of up to 60 mmHg even during the period of the maximum expected vasospasm. The absence of a rebound effect within the first hour after hypercapnia indicates that an improvement of the protocol is possible. The intervention may yield a therapeutic potential to prevent ischemic deficits after aneurysmal SAH.

Quantification of Cerebral Edema After Subarachnoid Hemorrhage

BACKGROUND

Global cerebral edema (GCE) is a manifestation of early brain injury (EBI) after subarachnoid hemorrhage (SAH) and is an independent risk factor for poor outcome. The lack of a quantitative method to measure GCE limits the study of its pathophysiology. The goal of this study is to develop a quantitative surrogate marker that represents GCE after SAH.

METHODS

Patients with spontaneous SAH were enrolled into a prospective observational database. Initial CT scans were graded for GCE using established qualitative criteria. Selective sulcal volume (SSV) was defined as total mL of sulcal volumes on axial CT slices above the most cranial section of the lateral ventricles to the last visible section. Using a semiautomatic threshold approach, sulcal regions were traced out with manual adjustments when necessary. The volume of sulci in each slice was calculated and multiplied by the slice thickness and number of slices to calculate the SSV. All volumetric analysis was performed using Medical Image Processing, Analysis and Visualization Version 7.0.1 (MIPAV).

RESULTS

A total of 109 subjects were included in our analysis. Mean selective sulcal volumes (SSV) differed between subjects with and without GCE 4.5 and 21.2 mL (P < 0.001). When separated into quartiles, the odds of qualitative GCE increases as SSV decreases. Compared to the highest SSV quartile, smaller SSV was associated with worse clinical outcomes.

CONCLUSION

GCE can be quantified using volumetric analysis of SSV measurements on routine CT scans. Smaller SSV on admission is predictive of worse clinical outcomes. SSV may be an important marker of EBI after SAH.

SIRT1 activation by resveratrol reduces brain edema and neuronal apoptosis in an experimental rat subarachnoid hemorrhage model

Early brain injury is considered to be a major risk that is related to the prognosis of subarachnoid hemorrhage (SAH). In SAH model rats, brain edema and apoptosis have been closely related with death rate and neurological function. Sirtuin 1 (SIRT1) was reported to be involved in apoptosis in cerebral ischemia and brain tumor formation through p53 deacetylation. The present study aimed to evaluate the role of SIRT1 in a rat endovascular perforation model of SAH. The SIRT1 activator resveratrol (RES) was administered 48 h prior to SAH induction and the SIRT1 inhibitor Sirtinol (SIR) was used to reverse the effects of RES on SIRT1 expression. Mortality rate, neurological function and brain water content were measured 24 h post‑SAH induction. Proteins associated with the blood brain barrier (BBB), apoptosis and SIRT1 in the cortex, such as zona occludens 1 (ZO‑1), occludin, claudin‑5, SIRT1, p53 and cleaved caspase3 were investigated. mRNA expression of the p53 downstream molecules including Bcl‑associated X protein, P53 upregulated modulator of apoptosis, Noxa and BH3 interacting‑domain death agonist were also investigated. Neuronal apoptosis was also investigated by immunofluorescence. RES pretreatment reduced the mortality rate and improved neurological function, which was consistent with reduced brain water content and neuronal apoptosis; these effects were partially reversed by co‑treatment with SIR. SIRT1 may reduce the brain water content by improvement of dysfunctional BBB permeability, and protein analysis revealed that both ZO‑1, occludin and claudin‑5 may be involved, and these effects were reversed by SIRT1 inhibition. SIRT1 may also affect apoptosis post‑SAH through p53 deacetylation, and the analysis of p53 related downstream pro‑apoptotic molecules supported this hypothesis. Localization of neuron specific apoptosis revealed that SIRT1 may regulate neuronal apoptosis following SAH. SIRT1 may also ease brain edema and neuronal protection through BBB improvement and p53 deacetylation. SIRT1 activators such as RES may have the potential to improve the prognosis of patients with SAH and clinical research should be investigated further.

Methylene blue attenuates neuroinflammation after subarachnoid hemorrhage in rats through the Akt/GSK-3β/MEF2D signaling pathway

Subarachnoid hemorrhage (SAH) is a serious medical problem with few effective pharmacotherapies available, and neuroinflammation has been identified as an important pathological process in early brain injury (EBI) after SAH. Methylene blue (MB) is an older drug that has been recently proven to exert extraordinary neuroprotective effects in several brain insults. However, no study has reported the beneficial effects of MB in SAH. In the current investigation, we studied the neuroprotective effects of MB in EBI after SAH and focused on its anti-inflammatory role. A total of 303 rats were subjected to an endovascular perforation process to produce an SAH model. We found that MB could significantly ameliorate brain edema secondary to BBB disruption and alleviate neurological dysfunction after SAH. MB administration also promoted the phosphorylation of Akt and GSK-3β, leading to an increased concentration of MEF2D in the nucleus. The cytokine IL-10 was up-regulated, and IL-1β, IL-6 and TNF-α were down-regulated after MB administration. MB administration could also alleviate neutrophil infiltration and microglia activation after SAH. MK2206, a selective inhibitor of Akt, abolished the neuroprotective effects of MB, inhibited the phosphorylation of Akt and prevented the nuclear localization of MEF2D. MK2206 also reduced the expression of IL-10 and increased the expression of pro-inflammatory cytokines. In conclusion, these data suggested that MB could ameliorate neuroinflammatory responses after SAH, and its anti-inflammatory effects might be exerted via activation of the Akt/GSK-3β/MEF2D pathway.

Effects of Fluid Treatment With Hydroxyethyl Starch on Renal Function in Patients With Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Recent reports have doubted the efficacy and safety of hydroxyethyl starch (HES) for volume resuscitation. HES has been reported to promote renal insufficiency particularly in sepsis and trauma patients. This analysis investigated the effects of HES 6% 130/0.4 for fluid therapy in patients with intact renal function who suffered aneurysmal subarachnoid hemorrhage (SAH).

METHODS

This retrospective analysis included 107 patients and was conducted in the framework of a clinical trial assessing the efficacy of magnesium sulfate in SAH. Because magnesium is renally eliminated, patients with renal insufficiency had been excluded. Standard therapy after aneurysm occlusion included the daily administration of HES 6% 130/0.4. Serum and urine creatinine and fluid balance were measured daily.

RESULTS

Patients received a daily mean of 1101±524 mL HES and 3353±1396 mL Ringer's solution. The highest creatinine values were recorded on day 3 after admission (0.88±0.25 mg/100 mL) and continuously decreased thereafter. In 6 patients, creatinine values temporarily increased by >0.3 mg/100 mL but recovered to admission values at the end of the observation period.

CONCLUSIONS

Concerning renal function, the first days after SAH seem to be a vulnerable phase in which a variety of interventions are performed, including contrast-enhanced neuroradiologic procedures. In this period, HES 6% 130/0.4 should be administered with caution. However, no patient suffered from renal failure and required temporary or permanent renal replacement therapy. These results suggest that the administration of HES 6% 130/0.4 is safe in SAH patients without preexisting renal insufficiency.

Feasibility and Safety of Mild Therapeutic Hypothermia in Poor-Grade Subarachnoid Hemorrhage: Prospective Pilot Study

Therapeutic hypothermia (TH) improves the neurological outcome in patients after cardiac arrest and neonatal hypoxic brain injury. We studied the safety and feasibility of mild TH in patients with poor-grade subarachnoid hemorrhage (SAH) after successful treatment. Patients were allocated randomly to either the TH group (34.5°C) or control group after successful clipping or coil embolization. Eleven patients received TH for 48 hours followed by 48 hours of slow rewarming. Vasospasm, delayed cerebral ischemia (DCI), functional outcome, mortality, and safety profiles were compared between groups. We enrolled 22 patients with poor-grade SAH (Hunt & Hess Scale 4, 5 and modified Fisher Scale 3, 4). In the TH group, 10 of 11 (90.9%) patients had a core body temperature of < 36°C for > 95% of the 48-hour treatment period. Fewer patients in the TH than control group (n = 11, each) had symptomatic vasospasms (18.1% vs. 36.4%, respectively) and DCI (36.3% vs. 45.6%, respectively), but these differences were not statistically significant. At 3 months, 54.5% of the TH group had a good-to-moderate functional outcome (0-3 on the modified Rankin Scale [mRS]) compared with 9.0% in the control group (P = 0.089). Mortality at 1 month was 36.3% in the control group compared with 0.0% in the TH group (P = 0.090). Mild TH is feasible and can be safely used in patients with poor-grade SAH. Additionally, it may reduce the risk of vasospasm and DCI, improving the functional outcomes and reducing mortality. A larger randomized controlled trial is warranted.

Emerging Markers of Early Brain Injury and Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage is characterized by a highly complex pathophysiology and results in neurologic deterioration after the inciting bleed. Despite its significant consequences, prompt diagnosis can be elusive and treatment is often administered too late. Early brain injury, which occurs within the first 72 hours after ictus, may be an important factor for delayed cerebral ischemia and poor overall outcome. Here, we explore the purported clinical and pathologic manifestations of early brain injury to identify biomarkers that could have prognostic value.

METHODS

We review the literature and discuss potential emerging markers of delayed cerebral ischemia in the context of early brain injury.

RESULTS

The following clinical features and biomarkers were examined: global cerebral edema, ictal loss of consciousness, ultra early angiographic vasospasm, continuous electroencephalogram monitoring, systemic inflammatory response syndrome, cellular mediators of the inflammatory response, and hematologic derangements.

CONCLUSIONS

Some of these markers possess independent value for determining the risk of complications after aneurysmal subarachnoid hemorrhage. However, their use is limited because of a variety of factors, but they do provide an avenue of further study to aid in diagnosis and management.

Early transition to comfort measures only in acute stroke patients: Analysis from the Get With The Guidelines-Stroke registry

BACKGROUND

Death after acute stroke often occurs after forgoing life-sustaining interventions. We sought to determine the patient and hospital characteristics associated with an early decision to transition to comfort measures only (CMO) after ischemic stroke (IS), intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH) in the Get With The Guidelines-Stroke registry.

METHODS

We identified patients with IS, ICH, or SAH between November 2009 and September 2013 who met study criteria. Early CMO was defined as the withdrawal of life-sustaining treatments and interventions by hospital day 0 or 1. Using multivariable logistic regression, we identified patient and hospital factors associated with an early (by hospital day 0 or 1) CMO order.

RESULTS

Among 963,525 patients from 1,675 hospitals, 54,794 (5.6%) had an early CMO order (IS: 3.0%; ICH: 19.4%; SAH: 13.1%). Early CMO use varied widely by hospital (range 0.6%-37.6% overall) and declined over time (from 6.1% in 2009 to 5.4% in 2013; p < 0.001). In multivariable analysis, older age, female sex, white race, Medicaid and self-pay/no insurance, arrival by ambulance, arrival off-hours, baseline nonambulatory status, and stroke type were independently associated with early CMO use (vs no early CMO). The correlation between hospital-level risk-adjusted mortality and the use of early CMO was stronger for SAH (r = 0.52) and ICH (r = 0.50) than AIS (r = 0.15) patients.

CONCLUSIONS

Early CMO was utilized in about 5% of stroke patients, being more common in ICH and SAH than IS. Early CMO use varies widely between hospitals and is influenced by patient and hospital characteristics.

Netrin-1 Preserves Blood-Brain Barrier Integrity Through Deleted in Colorectal Cancer/Focal Adhesion Kinase/RhoA Signaling Pathway Following Subarachnoid Hemorrhage in Rats

BACKGROUND

Netrin-1 (NTN-1) has been established to be a novel intrinsic regulator of blood-brain barrier (BBB) maintenance. This study was carried out to investigate the potential roles of exogenous NTN-1 in preserving BBB integrity after experimental subarachnoid hemorrhage (SAH) as well as the underlying mechanisms of its protective effects.

METHODS AND RESULTS

A total of 309 male Sprague-Dawley rats were subjected to an endovascular perforation model of SAH. Recombinant NTN-1 was administered intravenously 1 hour after SAH induction. NTN-1 small interfering RNA or Deleted in Colorectal Cancer small interfering RNA was administered intracerebroventricular at 48 hours before SAH. Focal adhesion kinase inhibitor was administered by intraperitoneal injection at 1 hour prior to SAH. Neurological scores, brain water content, BBB permeability, RhoA activity, Western blot, and immunofluorescence staining were evaluated. The expression of endogenous NTN-1 and its receptor Deleted in Colorectal Cancer were increased after SAH. Administration of exogenous NTN-1 significantly reduced brain water content and BBB permeability and ameliorated neurological deficits at 24 and 72 hours after SAH. Exogenous NTN-1 treatment significantly promoted phosphorylated focal adhesion kinase activation and inhibited RhoA activity, as well as upregulated the expression of ZO-1 and Occludin. Conversely, depletion of endogenous NTN-1 aggravated BBB breakdown and neurological impairments at 24 hours after SAH. The protective effects of NTN-1 at 24 hours after SAH were also abolished by pretreatment with Deleted in Colorectal Cancer small interfering RNA and focal adhesion kinase inhibitor.

CONCLUSIONS

NTN-1 treatment preserved BBB integrity and improved neurological functions through a Deleted in Colorectal Cancer/focal adhesion kinase/RhoA signaling pathway after SAH. Thus, NTN-1 may serve as a promising treatment to alleviate early brain injury following SAH.

Heparin and Heparin-Derivatives in Post-Subarachnoid Hemorrhage Brain Injury: A Multimodal Therapy for a Multimodal Disease

Pharmacologic efforts to improve outcomes following aneurysmal subarachnoid hemorrhage (aSAH) remain disappointing, likely owing to the complex nature of post-hemorrhage brain injury. Previous work suggests that heparin, due to the multimodal nature of its actions, reduces the incidence of clinical vasospasm and delayed cerebral ischemia that accompany the disease. This narrative review examines how heparin may mitigate the non-vasospastic pathological aspects of aSAH, particularly those related to neuroinflammation. Following a brief review of early brain injury in aSAH and heparin’s general pharmacology, we discuss potential mechanistic roles of heparin therapy in treating post-aSAH inflammatory injury. These roles include reducing ischemia-reperfusion injury, preventing leukocyte extravasation, modulating phagocyte activation, countering oxidative stress, and correcting blood-brain barrier dysfunction. Following a discussion of evidence to support these mechanistic roles, we provide a brief discussion of potential complications of heparin usage in aSAH. Our review suggests that heparin’s use in aSAH is not only safe, but effectively addresses a number of pathologies initiated by aSAH.

Systematic model of peripheral inflammation after subarachnoid hemorrhage

OBJECTIVE

To investigate inflammatory processes after aneurysmal subarachnoid hemorrhage (aSAH) with network models.

METHODS

This is a retrospective observational study of serum samples from 45 participants with aSAH analyzed at multiple predetermined time points: <24 hours, 24 to 48 hours, 3 to 5 days, and 6 to 8 days after aSAH. Concentrations of cytokines were measured with a 41-plex human immunoassay kit, and the Pearson correlation coefficients between all possible cytokine pairs were computed. Systematic network models were constructed on the basis of correlations between cytokine pairs for all participants and across injury severity. Trends of individual cytokines and correlations between them were examined simultaneously.

RESULTS

Network models revealed that systematic inflammatory activity peaks at 24 to 48 hours after the bleed. Individual cytokine levels changed significantly over time, exhibiting increasing, decreasing, and peaking trends. Platelet-derived growth factor (PDGF)-AA, PDGF-AB/BB, soluble CD40 ligand, and tumor necrosis factor-α (TNF-α) increased over time. Colony-stimulating factor (CSF) 3, interleukin (IL)-13, and FMS-like tyrosine kinase 3 ligand decreased over time. IL-6, IL-5, and IL-15 peaked and decreased. Some cytokines with insignificant trends show high correlations with other cytokines and vice versa. Many correlated cytokine clusters, including a platelet-derived factor cluster and an endothelial growth factor cluster, were observed at all times. Participants with higher clinical severity at admission had elevated levels of several proinflammatory and anti-inflammatory cytokines, including IL-6, CCL2, CCL11, CSF3, IL-8, IL-10, CX3CL1, and TNF-α, compared to those with lower clinical severity.

CONCLUSIONS

Combining reductionist and systematic techniques may lead to a better understanding of the underlying complexities of the inflammatory reaction after aSAH.

Effects of deferoxamine on blood-brain barrier disruption after subarachnoid hemorrhage

Blood brain barrier (BBB) disruption is a key mechanism of subarachnoid hemorrhage (SAH)-induced brain injury. This study examined the mechanism of iron-induced BBB disruption after SAH and investigated the potential therapeutic effect of iron chelation on SAH. Male adult Sprague-Dawley rats had an endovascular perforation of left internal carotid artery bifurcation or sham operation. The rats were treated with deferoxamine (DFX) or vehicle (100mg/kg) for a maximum of 7 days. Brain edema, BBB leakage, behavioral and cognitive impairment were examined. In SAH rat, the peak time of brain edema and BBB impairment in the cortex was at day 3 after SAH. SAH resulted in a significant increase in ferritin expression in the cortex. The ferritin positive cells were colocalized with endothelial cells, pericytes, astrocytes, microglia and neurons. Compared with vehicle, DFX caused less ferritin upregulation, brain water content, BBB impairment, behavioral and cognitive deficits in SAH rats. The results suggest iron overload could be a therapeutic target for SAH induced BBB damage.

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.

Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a neurological emergency with high risk of neurological decline and death. Although the presentation of a thunderclap headache or the worst headache of a patient's life easily triggers the evaluation for SAH, subtle presentations are still missed. The gold standard for diagnostic evaluation of SAH remains noncontrast head computed tomography (CT) followed by lumbar puncture if the CT is negative for SAH. Management of patients with SAH follows standard resuscitation of critically ill patients with the emphasis on reducing risks of rebleeding and avoiding secondary brain injuries.

Loss of Consciousness at Onset of Aneurysmal Subarachnoid Hemorrhage is Associated with Functional Outcomes in Good-Grade Patients

BACKGROUND

Transient loss of consciousness (LOC) is one of the most common presentations of aneurysmal subarachnoid hemorrhage (SAH) and may be an indicator of early brain injury. In this study, we examined the association of LOC and functional outcomes in patients with good-grade SAH.

METHODS

We searched the Subarachnoid Hemorrhage International Trialists Repository for patients who presented with LOC at ictus of SAH. A propensity score analysis was performed on good-grade patients (defined as World Federation of Neurosurgical Societies grade 1-3) to balance selected covariates between those with and without LOC. The primary outcome was Glasgow Outcome Score (GOS) at 3 months (with poor outcome defined as a GOS of 1-3). Secondary outcomes were delayed cerebral ischemia (DCI), rebleed, length of hospital stay, and time to death.

RESULTS

A propensity score-matching algorithm identified 336 patients (168 with and 168 without LOC at ictus). The proportion of patients with poor functional outcome at 3 months was significantly higher in the cohort with LOC at ictus compared with the matched cohort without LOC at ictus (30% vs. 19%; P = 0.02). There was a nonsignificant trend toward greater mortality in the patients with LOC at ictus (19% vs. 13%; P = 0.14). There were no significant differences in the secondary outcomes between the 2 cohorts.

CONCLUSIONS

LOC at ictus of SAH is associated with a higher rate of unfavorable functional outcomes but not of mortality, DCI, or rebleed in patients with good-grade SAH. Future studies should further investigate the putative mechanisms through which LOC mediates early brain injury in SAH.

Inhibition of Blood-Brain Barrier Disruption by an Apolipoprotein E-Mimetic Peptide Ameliorates Early Brain Injury in Experimental Subarachnoid Hemorrhage

Apolipoprotein E (ApoE)-mimetic peptides have been demonstrated to be beneficial in secondary brain injury following experimental subarachnoid hemorrhage (SAH). However, the molecular mechanisms underlying these benefits in SAH models have not been clearly identified. This study investigated whether an ApoE-mimetic peptide affords neuroprotection in early brain injury (EBI) following SAH by attenuating BBB disruption. SAH was induced by an endovascular perforation in young, healthy, male wild-type (WT) C57BL/6J mice. Multiple techniques, including MRI with T2-weighted imaging, ¹⁸ FDG PET-CT scanning and histological studies, were used to examine BBB integrity and neurological dysfunction in EBI following SAH. We found that SAH induced a significant increase of BBB permeability and neuron apoptosis, whereas ApoE-mimetic peptide treatment significantly reduced the degradation of tight junction proteins and endothelial cell apoptosis. These effects reduced brain edema and neuron apoptosis, increased cerebral glucose uptake, and improved neurological functions. Further investigation revealed that the ApoE-mimetic peptide inhibited the proinflammatory activators of MMP-9, including CypA, NF-κB, IL-6, TNF-α, and IL-1β, thereby ameliorating BBB disruption at the acute stage of SAH. Together, these data indicate that ApoE-mimetic peptide may be a novel and promising therapeutic strategy for EBI amelioration after SAH that are worthy of further study.

Hematologic counts as predictors of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

PURPOSE

Aneurysmal subarachnoid hemorrhage (SAH) is associated with high morbidity and mortality, but currently no single clinical method or ancillary test can reliably predict which subset of patients will develop delayed cerebral ischemia (DCI). The aim of this study was to find hematologic derangements and clinical factors present during the first 7 days after bleeding that could help identify patients at risk for development of DCI.

MATERIALS AND METHODS

Databank analysis of patients with SAH admitted between 2010 and 2012 in a single center. Data from demographics, imaging, laboratory, and clinical factors were collected. Statistical testing was conducted to test for association to the outcome, and multivariate logistic regression was used to design a predictive model.

RESULTS

Of 55 patients, 14 developed DCI (25%). Anemia and leukocytosis on the third day after bleeding were significantly correlated with the outcome (for anemia: P<.032; confidence interval, 1.12-15.16; odds ratio, 4.12; for leukocytosis: P<.046; confidence interval, 1.03-26.13; odds ratio, 5.18). Anemia and leukocytosis were still statistically significant after adjustment for age, sex, modified Fisher scale, and Hunt-Hess scale.

CONCLUSION

The presence of leukocytosis and anemia during the third day after SAH was statistically correlated with the occurrence of DCI.

Pentoxifylline Alleviates Early Brain Injury in a Rat Model of Subarachnoid Hemorrhage

BACKGROUND

Subarachnoid hemorrhage (SAH) is a severe cerebrovascular disease frequently caused by ruptured aneurysms. Early brain injury (EBI) is the primary cause of morbidity and mortality in patients diagnosed with SAH and is associated with increased intracranial pressure, decreased cerebral blood flow and cerebral ischemia. Pentoxifylline (PTX) is a methylxanthine derivative clinically proven to improve perfusion in the peripheral microcirculation and has been shown to have neuroprotective effects in brain trauma and global cerebral ischemia in experimental animal models. This study aimed to determine the effect of PTX in experimental SAH, which has not been investigated yet.

METHODS

An experimental SAH model was induced in male Wistar rats by autologous blood injection into the prechiasmatic cistern, and PTX was injected intraperitoneally immediately after SAH. The effects of PTX were evaluated 24 h after SAH via assessing the cerebral ultrastructure via transmission electron microscopy (TEM). Brain edema, blood-brain barrier (BBB) permeability, red blood cell deformability, tumor necrosis factor-alpha (TNF-alpha), nitrite-nitrate levels and apoptotic neuron death were also determined 24 h after SAH. The BBB permeability was measured by Evans blue (EB) extravasation, erythrocyte deformability was determined by filtration technique, and TNF-alpha and reactive nitrogen metobolites were analyzed in brain tissue by ELISA and spectral analysis, respectively. Apoptotic neurons were determined in brain sections by cleaved caspase-3 immunohistochemical analysis, and expression intensity was quantified using image J software.

RESULTS

Cerebral ultrastructure in SAH group animals revealed intense perivascular edema and distortion in the astrocyte foot processes. PTX treatment attenuated structural deterioration due to SAH. Brain water content, BBB permeability, TNF-alpha, nitrite-nitrate levels and apoptotic neuronal death were significantly increased 24 h after SAH and were significantly alleviated by PTX treatment. There was no significant change in red cell deformability after SAH.

CONCLUSIONS

Our results show that PTX reduces brain edema, BBB permeability, TNF-alpha expression, reactive nitrogen metobolites and apopotosis in experimental SAH. Based on our findings we suggest that PTX exerts neuroprotection against SAH-induced EBI, which might be associated with the inhibition of inflammation and apoptotic neuronal cell death.

Early Predictors of Fever in Patients with Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Fever is commonly observed in patients who have had aneurysmal subarachnoid hemorrhage (SAH), and it has been associated with the occurrence of delayed cerebral ischemia and worse outcomes in previous studies. Frequently, fever is not the result of bacterial infections, and distinction between infection-related fever and fever secondary to brain injury (also referred as central fever) can be challenging.

OBJECTIVES

The current study aimed to identify risk factors on admission for the development of central fever in patients with SAH.

METHODS

Databank analysis was performed using information from demographic data (age, gender), imaging (transcranial Doppler ultrasound, computed tomography, and cerebral angiogram), laboratory (white blood cell count, hemoglobin, renal function, and electrolytes), and clinical assessment (Hunt-Hess and modified Fisher scales on admission, occurrence of fever). A multivariate logistic regression model was created.

RESULTS

Of 55 patients, 32 developed fever during the first 7 days of hospital stay (58%). None of the patients had identifiable bacterial infections during their first week in the neurocritical care unit. Hunt-Hess scale >2 and leukocytosis on admission were associated to the development of central fever, even after correction in a logistic regression model.

CONCLUSION

Leukocytosis and a poor neurologic examination on admission might help predict which subset of patients with SAH are at higher risk of developing central fever early in their hospital stay.

Inflammasome Proteins in Cerebrospinal Fluid of Patients with Subarachnoid Hemorrhage are Biomarkers of Early Brain Injury and Functional Outcome

BACKGROUND

Aneurysmal subarachnoid hemorrhage (SAH) remains a devastating disease with significant morbidity and mortality. To date, clinical variables are still used to evaluate injury severity and prognosis. This study was designed to investigate the role of cerebrospinal fluid (CSF) inflammasome proteins as laboratory-based biomarkers of brain injury severity and outcome in SAH patients.

METHODS

Ten control patients and 24 SAH patients were prospectively enrolled in this study. CSF samples were collected within 72 hours after SAH. Levels of inflammasome proteins in the CSF, including NLRP1, ASC, and caspase-1 were analyzed.

RESULTS

Immunoblot analysis exhibited that levels of NLRP1, ASC and caspase-1 were elevated in the CSF of SAH patients (P < 0.0001, P = 0.0178, and P < 0.0001, respectively). In the group of SAH patients, these inflammasome proteins were significantly higher in the patients with cerebral edema on computed tomographic scans (P = 0.0002, P = 0.0005, and P = 0.0004, respectively), and in the patients with acute hydrocephalus (P = 0.0009, P = 0.00017, and P = 0.0016, respectively). Higher levels of inflammasome proteins were associated with severe SAH and poor outcome 3 months after the SAH. High level of NLRP1 was the independent risk factor of poor outcome after SAH (P = 0.049, odds ratio = 1.730).

CONCLUSIONS

Inflammasome proteins are potential biomarkers to assess early brain injury and to predict functional outcome after SAH.

Protective effect 3,4-dihydroxyphenylethanol in subarachnoid hemorrhage provoked oxidative neuropathy

Clinical studies have indicated that early brain injury (EBI) following subarachnoid hemorrhage (SAH) is associated with fatal outcomes. Oxidative stress and brain edema are the characteristic pathological events in occurrence EBI following SAH. The present study aimed to examine the effect of 3,4-dihydroxyphenylethanol (DOPET) against SAH-induced EBI, and to demonstrate whether the effect is associated with its potent free radical scavenging property. SAH was induced in rats using an endovascular perforation technique, and 24 h later the rats displayed diminished neurological scores and brain edema. Furthermore, elevated malondialdehyde (an index of lipid peroxidation) and depleted levels of antioxidants were observed in the rat cerebral cortex tissue. Quantitative polymerase chain reaction analysis indicated the upregulated mRNA expression of the apoptotic markers caspase-3 and -9 in the cerebral cortex. Furthermore, the protein expression levels of the proinflammatory cytokines tumor necrosis factor-α, interleukin (IL)-1β and IL-6 were significantly upregulated in SAH-induced rats. By constrast, treatment with DOPET significantly attenuated EBI by reducing brain edema, elevation of antioxidant status, inhibition of apoptosis and inflammation. In this context, DOPET may be a potent agent in the treatment of EBI following SAH, as a result of its free radical scavenging capacity.

Dexmedetomidine post-treatment induces neuroprotection via activation of extracellular signal-regulated kinase in rats with subarachnoid haemorrhage

BACKGROUND

Dexmedetomidine, a sedative agent, provides neuroprotection when administered during or before brain ischaemia. This study was designed to determine whether dexmedetomidine post-treatment induces neuroprotection against subarachnoid haemorrhage (SAH) and the mechanisms for this effect.

METHODS

Subarachnoid haemorrhage was induced by endovascular perforation to the junction of the right middle and anterior cerebral arteries in adult rats. Dexmedetomidine was applied immediately or 2 h after onset of SAH. Neurological outcome was evaluated 2 days after SAH. Right frontal cortex area 1 was harvested 24 h after SAH for western blotting.

RESULTS

Subarachnoid haemorrhage reduced neurological scores and increased brain oedema and blood-brain barrier permeability. These effects were attenuated by dexmedetomidine post-treatment. Neuroprotection by dexmedetomidine was abolished by PD98095, an inhibitor of extracellular signal-regulated kinase (ERK) activation. Phospho-ERK, the activated form of ERK, was increased by dexmedetomidine; this activation was inhibited by PD98095.

CONCLUSIONS

Dexmedetomidine post-treatment provides neuroprotection against SAH. This effect appears to be mediated by ERK.

Hydrogen sulfide attenuates brain edema in early brain injury after subarachnoid hemorrhage in rats: Possible involvement of MMP-9 induced blood-brain barrier disruption and AQP4 expression

AIMS

This study investigated the effect of H2S on brain edema formation and the possible underlying mechanisms in early brain injury (EBI) of SAH using the endovascular perforation model.

METHODS

96 male rats were randomly divided into four groups: sham group, SAH+vehicle group, SAH+low-dosage NaHS group, and SAH+high-dosage NaHS group. Brain samples were used for brain water content and blood-brain barrier (BBB) leakage measurement, gelatin zymography, Western blot and immunohistochemistry.

RESULTS

H2S markedly attenuated brain edema formation and apoptotic cell death, improved neurological dysfunction in the acute stage of SAH. The possible mechanisms of H2S's effect on brain edema formation were through preventing BBB disruption and reducing APQ4 expression on astrocytes. In detail, H2S prevented BBB disruption by inhibiting MMP-9 induced tight junction proteins (TJPs) degradation. H2S down-regulated AQP4 expression on astrocytes by suppressing glial cell activation and pro-inflammatory cytokines secretion.

CONCLUSION

Taken together, this study showed that H2S attenuated brain edema formation partially by inhibiting the degradation of TJPs via reducing MMP-9 expression/activity and suppressing AQP4 expression via alleviating glia activation and pro-inflammatory cytokines secretion.

Application of Blood-Brain Barrier Permeability Imaging in Global Cerebral Edema

BACKGROUND AND PURPOSE

Blood-brain barrier permeability is not routinely evaluated in the clinical setting. Global cerebral edema occurs after SAH and is associated with BBB disruption. Detection of global cerebral edema using current imaging techniques is challenging. Our purpose was to apply blood-brain barrier permeability imaging in patients with global cerebral edema by using extended CT perfusion.

MATERIALS AND METHODS

Patients with SAH underwent CTP in the early phase after aneurysmal rupture (days 0-3) and were classified as having global cerebral edema or nonglobal cerebral edema using established noncontrast CT criteria. CTP data were postprocessed into blood-brain barrier permeability quantitative maps of PS (permeability surface-area product), K(trans) (volume transfer constant from blood plasma to extravascular extracellular space), Kep (washout rate constant of the contrast agent from extravascular extracellular space to intravascular space), VE (extravascular extracellular space volume per unit of tissue volume), VP (plasmatic volume per unit of tissue volume), and F (plasma flow) by using Olea Sphere software. Mean values were compared using t tests.

RESULTS

Twenty-two patients were included in the analysis. Kep (1.32 versus 1.52, P < .0001), K(trans) (0.15 versus 0.19, P < .0001), VP (0.51 versus 0.57, P = .0007), and F (1176 versus 1329, P = .0001) were decreased in global cerebral edema compared with nonglobal cerebral edema while VE (0.81 versus 0.39, P < .0001) was increased.

CONCLUSIONS

Extended CTP was used to evaluate blood-brain barrier permeability in patients with SAH with and without global cerebral edema. Kep is an important indicator of altered blood-brain barrier permeability in patients with decreased blood flow, as Kep is flow-independent. Further study of blood-brain barrier permeability is needed to improve diagnosis and monitoring of global cerebral edema.

Causal Structure of Brain Physiology after Brain Injury from Subarachnoid Hemorrhage

High frequency physiologic data are routinely generated for intensive care patients. While massive amounts of data make it difficult for clinicians to extract meaningful signals, these data could provide insight into the state of critically ill patients and guide interventions. We develop uniquely customized computational methods to uncover the causal structure within systemic and brain physiologic measures recorded in a neurological intensive care unit after subarachnoid hemorrhage. While the data have many missing values, poor signal-to-noise ratio, and are composed from a heterogeneous patient population, our advanced imputation and causal inference techniques enable physiologic models to be learned for individuals. Our analyses confirm that complex physiologic relationships including demand and supply of oxygen underlie brain oxygen measurements and that mechanisms for brain swelling early after injury may differ from those that develop in a delayed fashion. These inference methods will enable wider use of ICU data to understand patient physiology.

Identifying Meningitis During an Anthrax Mass Casualty Incident: Systematic Review of Systemic Anthrax Since 1880

BACKGROUND

Bacillus anthracis, the causative agent of anthrax, is a potential bioterrorism agent. Anthrax meningitis is a common manifestation of B. anthracis infection, has high mortality, and requires more aggressive treatment than anthrax without meningitis. Its rapid identification and treatment are essential for successful management of an anthrax mass casualty incident.

METHODS

Three hundred six published reports from 1880 through 2013 met predefined inclusion criteria. We calculated descriptive statistics for abstracted cases and conducted multivariable regression on separate derivation and validation cohorts to identify clinical diagnostic and prognostic factors for anthrax meningitis.

RESULTS

One hundred thirty-two of 363 (36%) cases with systemic anthrax met anthrax meningitis criteria. Severe headache, altered mental status, meningeal signs, and other neurological signs at presentation independently predicted meningitis in the derivation cohort and were tested as a 4-item assessment tool for use during anthrax mass casualty incidents. Presence of any 1 factor on admission had a sensitivity for finding anthrax meningitis of 89% (83%) in the adult (pediatric) validation cohorts. Anthrax meningitis was unlikely in the absence of any of these signs or symptoms (likelihood ratio [LR]- = 0.12 [0.19] for adult [pediatric] cohorts), while presence of 2 or more made meningitis very likely (LR+ = 26.5 [30.0]). Survival of anthrax meningitis was predicted by treatment with a bactericidal agent (P = .005) and use of multiple antimicrobials (P = .01).

CONCLUSIONS

We developed an evidence-based assessment tool for screening patients for meningitis during an anthrax mass casualty incident. Its use could improve both patient outcomes and resource allocation in such an event.

Intraoperative mild hypothermia for postoperative neurological deficits in people with intracranial aneurysm

BACKGROUND

Rupture of an intracranial aneurysm causes aneurysmal subarachnoid haemorrhage, which is one of the most devastating clinical conditions. It can be classified into five Grades using the Hunt-Hess or World Federation of Neurological Surgeons (WFNS) scale. Grades 4 and 5 predict poor prognosis and are known as 'poor grade', while grade 1, 2, and 3 are known as 'good grade'. Disturbances of intracranial homeostasis and brain metabolism are known to play certain roles in the sequelae. Hypothermia has a long history of being used to reduce metabolic rate, thereby protecting organs where metabolism is disturbed, and may potentially cause harm.

OBJECTIVES

To assess the effect of intraoperative mild hypothermia on postoperative death and neurological deficits in people with ruptured or unruptured intracranial aneurysms.

SEARCH METHODS

We updated the search in the Cochrane Stroke Group Trials Register (August 2015), the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 8), WHO International Clinical Trials Registry Platform (ICTRP; December 2015), MEDLINE (1950 to September 2015), EMBASE (1980 to September 2015), Science Citation Index (1900 to September 2015), and 11 Chinese databases (September 2015). We also searched ongoing trials registers (September 2015) and scanned reference lists of retrieved records.

SELECTION CRITERIA

We included only randomised controlled trials that compared intraoperative mild hypothermia (32°C to 35°C) with control (no hypothermia) in people with ruptured or unruptured intracranial aneurysms.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials and assessed the risk of bias for each included study. We presented data as risk ratio (RR) and risk difference (RD) with 95% confidence intervals (CI).

MAIN RESULTS

We included three studies, enrolling 1158 participants. Each study reported an increased rate of recovery with intraoperative mild hypothermia, but the effect sizes were not sufficient for certainty. A total of 1086 of the 1158 participants (93.8%) had good grade aneurysmal subarachnoid haemorrhage. Seventy-six of 577 participants (13.1%) who received hypothermia and 93 of 581 participants (16.0%) who did not receive hypothermia were dead or dependent (RR 0.82; 95% CI 0.62 to 1.09; RD -0.03; 95% CI -0.07 to 0.01, moderate-quality evidence) after three months.Reported unfavourable outcomes did not differ between participants with or without hypothermia. The quality of evidence for these outcomes remains unclear because the outcomes were reported in a variety of ways. No decompressive craniectomy or corticectomy was reported. Thirty-six of 577 (6.2%) participants with hypothermia and 40 of 581 (6.9%) participants without hypothermia had infarction. Thirty-four of 577 (6%) participants with hypothermia and 32 of the 581 (5.5%) participants without hypothermia had clinical vasospasm (temporary deficits).Duration of hospital stay was not reported. Only one study with 112 participants reported discharge destinations: 43 of 55 (78.2%) participants with hypothermia and 39 of 57 (68.4%) participants in the control group were discharged home. The remaining participants were discharged to other facilities.Thirty-nine of 577 (6.8%) participants with hypothermia and 39 of 581 (6.7%) participants without hypothermia had infections. Six of 577 (1%) participants with hypothermia and 6 of 581 (1%) participants without hypothermia had cardiac arrhythmia.

AUTHORS' CONCLUSIONS

It remains possible that intraoperative mild hypothermia could prevent death or dependency in activities of daily living in people with good grade aneurysmal subarachnoid haemorrhage. However, the confidence intervals around this estimate include the possibility of both benefit and harm. There was insufficient information to draw any conclusions about the effects of intraoperative mild hypothermia in people with poor grade aneurysmal subarachnoid haemorrhage or without subarachnoid haemorrhage. We did not identify any reliable evidence to support the routine use of intraoperative mild hypothermia. A high-quality randomised clinical trial of intraoperative mild hypothermia for postoperative neurological deficits in people with poor grade aneurysmal subarachnoid haemorrhage might be feasible.

Atorvastatin ameliorates early brain injury after subarachnoid hemorrhage via inhibition of AQP4 expression in rabbits

The therapeutic effects of atorvastatin on early brain injury (EBI), cerebral edema and its association with aquaporin 4 (AQP4) were studied in rabbits after subarachnoid hemorrhage (SAH) using western blot analysis and the dry-wet method. Seventy-two healthy male New Zealand rabbits weighing between 2.5 and 3.2 kg were randomly divided into three groups: the SAH group (n=24), sham-operated group (n=24) and the SAH + atorvastatin group (n=24). A double SAH model was employed. The sham-operated group were injected with the same dose of saline solution, the SAH + atorvastatin group received atorvastatin 20 mg/kg/day after SAH. All rabbit brain samples were taken at 72 h after the SAH model was established successfully. Brain edema was detected using the dry-wet method after experimental SAH was induced; AQP4 and caspase-3 expression was measured by western blot analysis, and neuronal apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) staining at 72 h after SAH. The results indicated that brain edema and injury appeared soon after SAH, while brain edema and EBI were ameliorated and increased behavior scores were noted after prophylactic use of atorvastatin. Compared with the SAH group, the level of AQP4 and the cerebral content of water was significantly decreased (P<0.01) by atorvastatin, and TUNEL staining and studying the expression of caspase-3 showed that the apoptosis of neurons was reduced markedly both in the hippocampus and brain cortex by atorvastatin. The results suggest that atorvastatin ameliorated brain edema and EBI after SAH, which was related to its inhibition of AQP4 expression. Our findings provide evidence that atorvastatin is an effective and well-tolerated approach for treating SAH in various clinical settings.

Brain injury visible on early MRI after subarachnoid hemorrhage might predict neurological impairment and functional outcome

BACKGROUND

In subarachnoid hemorrhage (SAH), brain injury visible within 48 h of onset may impact on admission neurological disability and 3-month functional outcome. With volumetric MRI, we measured the volume of brain injury visible after SAH, and assessed the association with admission clinical grade and 3-month functional outcome.

METHODS

Retrospective cohort study conducted in the Neurocritical Care Division, Columbia University Medical Center, New York, USA. On brain MRI acquired within 48 h of SAH-onset and before aneurysm-securing (n = 27), two blinded readers measured DWI and FLAIR-lesion volumes using semi-automated, computer segmentation software.

RESULTS

Compared to post-resuscitation Hunt-Hess grade 1-3 (70 %), high-grade patients (30 %) had higher lesion volumes on DWI (34 ml [IQR: 0-64] vs. 2 ml [IQR: 0.5-7], P = 0.02) and on FLAIR (81 ml [IQR: 24-127] vs. 3 ml [IQR: 0-27], P = 0.02). On DWI, each 10 ml increase in lesion volume was associated with a 101 %-increase in the odds of presenting with 1 grade more in the Hunt-Hess scale (aOR 2.01, 95 % CI 1.10-3.68, P = 0.02), but was not significantly associated with 3-month outcome. On FLAIR, each 10 ml increase in lesion volume was associated with 34 % higher odds of a 1-point increase on the Hunt-Hess scale (aOR 1.34, 95 % CI 1.06-1.68, P = 0.01) and 139 % higher odds of a 1-point increase on the 3-month mRS (aOR 2.39, 95 % CI 1.13-5.07, P = 0.02).

CONCLUSION

The volume of brain injury visible on DWI and FLAIR within 48 h after SAH is proportional to neurological impairment on admission. Moreover, FLAIR-imaging implicates chronic brain injury-predating SAH-as potentially relevant cause of poor functional outcome.

Inhibition of the Receptor for Advanced Glycation End-Products (RAGE) Attenuates Neuroinflammation While Sensitizing Cortical Neurons Towards Death in Experimental Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a threatening and devastating neurological insult with high mortality and morbidity rates. Despite considerable efforts, the underlying pathophysiological mechanisms are still poorly understood. The receptor for advanced glycation end products (RAGE) is a multiligand receptor that has been implicated in various pathological conditions. We previously showed that RAGE was upregulated and may be involved in pathophysiology of SAH. In the current study, we investigated its potential role in SAH. We found that the upregulation of RAGE after SAH was NF-κB-dependent positive feedback regulation. Further, pharmacological inhibition of RAGE attenuated neuroinflammation, indicating a possible contributive role of RAGE in inflammation-associated brain injury after SAH. Conversely, however, inhibition of RAGE sensitized neurons, exacerbating cell death, which correlated with augmented apoptosis and diminished autophagy, suggesting that activation of RAGE may protect against SAH-induced neuronal injury. Furthermore, we demonstrate that inhibition of RAGE significantly reduced brain edema and improved neurological function at day 1 but not at day 3 post-SAH. Taken together, these results suggest that RAGE exerts dual role after SAH. Our findings also suggest caution should be exercised in setting RAGE-targeted treatment for SAH.

Intraoperative Targeted Temperature Management in Acute Brain and Spinal Cord Injury

Acute brain and spinal cord injuries affect hundreds of thousands of people worldwide. Though advances in pre-hospital and emergency and neurocritical care have improved the survival of some to these devastating diseases, very few clinical trials of potential neuro-protective strategies have produced promising results. Medical therapies such as targeted temperature management (TTM) have been trialed in traumatic brain injury (TBI), spinal cord injury (SCI), acute ischemic stroke (AIS), subarachnoid hemorrhage (SAH), and intracranial hemorrhage (ICH), but in no study has a meaningful effect on outcome been demonstrated. To this end, patient selection for potential neuro-protective therapies such as TTM may be the most important factor to effectively demonstrate efficacy in clinical trials. The use of TTM as a strategy to treat and prevent secondary neuronal damage in the intraoperative setting is an area of ongoing investigation. In this review we will discuss recent and ongoing studies that address the role of TTM in combination with surgical approaches for different types of brain injury.

Assessment of the Correlations Between Brain Weight and Brain Edema in Experimental Subarachnoid Hemorrhage

Because brain edema is correlated with poor outcome in clinical subarachnoid hemorrhage (SAH), appropriate evaluation methods for brain edema are important in experimental SAH studies. Although brain water content (BWC) is widely used to evaluate brain edema in stroke research, the usefulness of brain weight is undetermined. In this study, we examined the role of brain weight in the evaluation of brain edema in experimental SAH. The endovascular perforation model of SAH was used, and rats were assessed by neurological scoring (NS). The brains were quickly removed at 24 h after the operation, and the weights of wet cerebrum (WWC) and dry cerebrum (WDC) were measured to determine the brain water content (BWC). The correlations of those values with each other and to body weight (BW) were then examined to reveal the significance of brain weight. The rats were assigned to sham-operated (n = 8) and SAH (n = 16) groups. There were no significant differences in WWC between the groups (p = 0.61). WWC was correlated with BWC but not with NS in all rats. In addition, WWC was clearly correlated with BW and WDC, which is thought to substitute for the original brain weight. From these results, we suggest that the measurement of brain weight as an evaluation of brain edema is limited and that BW and original brain volume can be confounding factors in evaluation.

The Role of Matricellular Proteins in Brain Edema after Subarachnoid Hemorrhage

Accumulated evidence suggests that blood-brain barrier disruption or brain edema is an important pathologic manifestation for poor outcome after aneurysmal subarachnoid hemorrhage. Many molecules may be involved, acting simultaneously or at different stages during blood-brain barrier disruption via multiple independent or interconnected signaling pathways. Matricellular protein is a class of nonstructural, secreted, and multifunctional extracellular matrix proteins, which potentially mediates brain edema formation. This study reviews the role of osteopontin and tenascin-C, representatives of matricellular proteins, in the context of brain edema formation after subarachnoid hemorrhage in both clinical and experimental settings.

Bilaterally isolated abducens palsy after an aneursym rupture is related with intracranial hypertension

BACKGROUND

Bilateral and isolated abducens nerve palsy is a rare initial presentation after aneurysms rupture. Several possible mechanisms including intracranial hypertension have been purposed. To date, there have been no reports with objective measurements to demonstrate the relationship between intracranial pressure and isolated abducens palsy in the setting of acute subarachnoid hemorrhage due to aneurysm rupture.

FINDINGS

A 50 year-old female presented with severe headache and bilaterally isolated abducens nerve palsy. A series of image studies showed a ruptured aneurysm over right internal carotid artery and posterior communicating artery bifurcation with minimal subarachnoid hemorrhage. Surgery of aneurysm clipping was performed and intracranial pressure monitoring was applied. Postoperatively no new neurological deficit developed but persistent headache and increased intracranial pressure measured by a fiber-optic device had been observed. The intracranial hypertension then decreased gradually with rapid recovery from the bilateral abducens palsy 7 days after the surgery. The relationship between postoperative intracranial pressure, subarachnoid hematoma and isolated abducens palsy are illustrated.

CONCLUSIONS

The report demonstrated the clinical presentation of bilaterally isolated abducens palsy after an intracranial aneurysm rupture is related with the increased intracranial pressure level, rather than the hematoma compression to the nerve or vasospasm of pontine branches of basilar artery.