Early global brain oedema in relation to clinical admission parameters and outcome in patients with aneurysmal subarachnoid haemorrhage

Recombinant soluble form of receptor for advanced glycation end products ameliorates microcirculation impairment and neuroinflammation after subarachnoid hemorrhage

Impaired cerebral microcirculation after subarachnoid hemorrhage (SAH) has been shown to be related to delayed ischemic neurological deficits (DIND). We previously demonstrated the involvement of the receptor for advanced glycation end products (RAGE) in the pathogenesis of SAH related neuronal death. In the present study, we aimed to investigate the therapeutic effects of a recombinant soluble form of RAGE (sRAGE) on microcirculation impairment following SAH. Intrathecal injection of autologous blood in rats, mixed primary astrocyte and microglia cultures exposed to hemolysates and endothelial cells ​(ECs) from human brain microvascular exposed to glia-conditioned medium or SAH patient's CSF were used as experimental SAH models in vivo and in vitro. The results indicated that intrathecal administration of recombinant sRAGE significantly ameliorated the vasoconstriction of cortical arterioles and associated perfusion impairment, brain edema, reduced cell death, endothelial dysfunction, and improved motor performance at 24 and 48 ​h after SAH induction in rats. The in vitro results further showed that recombinant sRAGE significantly reduced astrocyte swelling and microglia activation, in parallel with decreased mRNA expression levels of pro-inflammatory cytokines including interleukin-6 (IL-6) and interleukin-1β (IL-1β) in vitro. Moreover, the in vitro model of SAH-induced p-eNOS and eNOS suppression, along with stress fiber formation in brain microvascular ECs, was effectively reversed by sRAGE treatment and led to a decrease in cleaved-caspase 3 expression. In summary, recombinant sRAGE effectively lessened microcirculation impairment and vascular injury after SAH via the mechanism of anti-inflammation, which may provide a potential therapeutic strategy for SAH.

Lower Serum Iron Level Predicts Postoperative Global Cerebral Edema Following Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Iron plays an important role in neuronal injury and edema formation after intracranial hemorrhage. However, the role of serum iron in aneurysmal subarachnoid hemorrhage (aSAH) is yet to be well-established. This study aims to identify whether serum iron could predict postoperative global cerebral edema (GCE) and poor outcome in aSAH.

METHODS

847 patients' aSAH clinical data were retrospectively collected at the First Affiliated Hospital of Fujian Medical University. Data on demographics, clinical characteristics, and laboratory values were collected and analyzed through univariate and multivariate analyses. Propensity score matching (PSM) analysis was performed to balance the baseline differences between the groups.

RESULTS

The incidence of high-grade global cerebral edema (H-GCE) following aSAH was 12.99% (110/847). Serum iron levels [odds ratio (OR) = 1.143; 95% confidence interval (CI), (1.097-1.191); p < 0.001] were associated with the occurrence of H-GCE following aSAH in the univariate analysis. This association remained statistically significant even after adjusting for other variables in the multivariate model, with serum iron having an OR of 1.091 (95% CI, 1.043-1.141; p < 0.001) for GCE. After 1:1 PSM, serum iron levels ≤ 10.7 µmol/L remained a significant independent predictor of GCE (p = 0.002). The receiver operating characteristic (ROC) curve analysis determined that a serum iron cut-off value of ≤ 10.7 µmol/L was optimal for predicting H-GCE [Areas under the ROC curves (AUC) = 0.701, 95% CI, (0.669-0.732), p < 0.001; sensitivity, 67.27%; specificity, 63.77%] in patients with aSAH. Additionally, a trend was observed in which higher Hunt-Hess grades (HH grade) were associated with lower serum iron levels, and higher modified Fisher grades (mFisher grade) were associated with lower serum iron levels. In addition, the serum iron level was also associated with a 3-month functional neurological outcome (p < 0.001).

CONCLUSIONS

The results of this study indicate that a decreased serum iron level serves as a clinically significant biomarker for the prediction of postoperative GCE and a poor outcome at 3-months in patients with aSAH.

A Novel Surgical Classification of the Sylvian Fissure and Its Implications on the Clinical and Radiological Outcomes of Patients Undergoing Clipping for Unruptured Middle Cerebral Artery Aneurysms

BACKGROUND

The main access route for middle cerebral artery (MCA) aneurysms is the transsylvian approach. Although Sylvian fissure (SF) variations have been assessed, none have examined how this affects MCA aneurysm surgery. The objective of this study is to investigate how SF variants affect clinical and radiological outcomes for surgically-treated unruptured MCA aneurysms.

METHODS

This retrospective study examined consecutive unruptured MCA aneurysms in 101 patients undergoing SF dissection and aneurysm clipping. SF anatomical variants were categorized using a novel functional anatomical classification: Type I: Wide straight, Type II: Wide with frontal and/or temporal opercula herniation, Type III: Narrow straight, and Type IV: Narrow with frontal and/or temporal opercula herniation. The relationships between SF variants and postoperative edema, ischemia, hemorrhage, vasospasm, and Glasgow Outcome Scale (GOS) were analyzed.

RESULTS

Study included 101 patients (53.5% women), 60.9 ± 9.4 (range 24-78) years. SF types were 29.7% Type I, 19.8% Type II, 35.6% Type III, and 14.9% Type IV. The SF type with the highest proportion of females was Type IV (n = 11, 73.3%), while it was Type III for males (n = 23, 63.9%) (P = 0.03). There were significant differences between SF types, ischemia, and edema (P < 0.001, P = 0.008, respectively). Although narrow SF types had poorer GOS scores (P = 0.055), there were no significant differences between SF types and GOS, postoperative hemorrhage, vasospasm, or hospital stay.

CONCLUSIONS

Sylvian fissure variants may impact intraoperative complications during aneurysm surgery. Thus, presurgical determination of SF variants can predict surgical difficulties, thereby potentially reducing morbidity for patients with MCA aneurysms and other pathologies requiring SF dissection.

Subacute phase of subarachnoid haemorrhage in female rats: Increased intracranial pressure, vascular changes and impaired sensorimotor function

OBJECTIVE

Early brain injury (EBI) and delayed cerebral ischemia (DCI) after subarachnoid haemorrhage (SAH) has devastating consequences but therapeutic options and the underlying pathogenesis remain poorly understood despite extensive preclinical and clinical research. One of the drawbacks of most preclinical studies to date is that the mechanisms behind DCI after SAH are studied only in male animals. In this study we therefore established a female rat model of SAH in order to determine subacute pathophysiological changes that may contribute to DCI in females.

METHODS

Experimental SAH was induced in female rats by intracisternal injection of 300 μL of autologous blood. Sham operation served as a control. Neurological deficits and intracranial pressure measurements were evaluated at both 1 and 2 days after surgery. Additionally, changes in cerebral vascular contractility were evaluated 2 days after surgery using wire myography.

RESULTS

SAH in female rats resulted in sensorimotor deficits and decreased general wellbeing on both day 1 and day 2 after SAH. Intracranial pressure uniformly increased in all rats subjected to SAH on day 1. On day 2 the intracranial pressure had increased further, decreased slightly or remained at the level seen on day 1. Furthermore, female rats subjected to SAH developed cortical brain edema. Cerebral arteries, isolated 2 days after SAH, exhibited increased vascular contractions to endothelin-1 and 5-carboxamidotryptamine.

CONCLUSION

In the subacute phase after SAH in female rats, we observed increased intracranial pressure, decreased wellbeing, sensorimotor deficits, increased vascular contractility and cortical brain edema. Collectively, these pathophysiological changes may contribute to DCI after SAH in females. Previous studies reported similar pathophysiological changes for male rats in the subacute phase after SAH. Thus, prevention of these gender-independent mechanisms may provide the basis for a universal treatment strategy for DCI after SAH. Nevertheless, preclinical studies of potential therapies should employ both male and female SAH models.

Time and predictors of time to treatment for aneurysmal subarachnoid haemorrhage (aSAH): a systematic review

BACKGROUND

Aneurysmal subarachnoid haemorrhage (aSAH) is a serious form of stroke, for which rapid access to specialist neurocritical care is associated with better outcomes. Delays in the treatment of aSAH appear to be common and may contribute to poor outcomes. We have a limited understanding of the extent and causes of these delays, which hinders the development of interventions to reduce delays and improve outcomes. The aim of this systematic review was to quantify and identify factors associated with time to treatment in aSAH.

METHODS

This systematic review was performed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines and was registered in PROSPERO (Reg. No. CRD42019132748). We searched four electronic databases (MEDLINE, EMBASE, Web of Science and Google Scholar) for manuscripts published from January 1998 using pre-designated search terms and search strategy. Main outcomes were duration of delays of time intervals from onset of aSAH to definitive treatment and/or factors related to time to treatment.

RESULTS

A total of 64 studies with 16 different time intervals in the pathway of aSAH patients were identified. Measures of time to treatment varied between studies (e.g. cut-off timepoints or absolute mean/median duration). Factors associated with time to treatment fell into two categories-individual (n = 9 factors, e.g. age, sex and clinical characteristics) and health system (n = 8 factors, e.g. pre-hospital delay or presentation out-of-hours). Demographic factors were not associated with time to treatment. More severe aSAH reduced treatment delay in most studies. Pre-hospital delays (patients delay, late referral, late arrival of ambulance, being transferred between hospitals or arriving at the hospital outside of office hours) were associated with treatment delay. In-hospital factors (patients with complications, procedure before definitive treatment, slow work-up and type of treatment) were less associated with treatment delay.

CONCLUSIONS

The pathway from onset to definitive treatment of patients with aSAH consists of multiple stages with multiple influencing factors. This review provides the first comprehensive understanding of extent and factors associated with time to treatment of aSAH. There is an opportunity to target modifiable factors to reduce time to treatment, but further research considering more factors are needed.

Automated Quantification of Reduced Sulcal Volume Identifies Early Brain Injury After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Early brain injury may be a more significant contributor to poor outcome after aneurysmal subarachnoid hemorrhage (aSAH) than vasospasm and delayed cerebral ischemia. However, studying this process has been hampered by lack of a means of quantifying the spectrum of injury. Global cerebral edema (GCE) is the most widely accepted manifestation of early brain injury but is currently assessed only through subjective, qualitative or semi-quantitative means. Selective sulcal volume (SSV), the CSF volume above the lateral ventricles, has been proposed as a quantitative biomarker of GCE, but is time-consuming to measure manually. Here we implement an automated algorithm to extract SSV and evaluate the age-dependent relationship of reduced SSV on early outcomes after aSAH.

METHODS

We selected all adults with aSAH admitted to a single institution with imaging within 72 hours of ictus. Scans were assessed for qualitative presence of GCE. SSV was automatically segmented from serial CTs using a deep learning-based approach. Early SSV was the lowest SSV from all early scans. Modified Rankin Scale score of 4 to 6 at hospital discharge was classified as a poor outcome.

RESULTS

Two hundred forty-four patients with aSAH were included. Sixty-five (27%) had GCE on admission while 24 developed it subsequently within 72 hours. Median SSV on admission was 10.7 mL but frequently decreased, with minimum early SSV being 3.0 mL (interquartile range, 0.3-11.9). Early SSV below 5 mL was highly predictive of qualitative GCE (area under receiver-operating-characteristic curve, 0.90). Reduced early SSV was an independent predictor of poor outcome, with a stronger effect in younger patients.

CONCLUSIONS

Automated assessment of SSV provides an objective biomarker of GCE that can be leveraged to quantify early brain injury and dissect its impact on outcomes after aSAH. Such quantitative analysis suggests that GCE may be more impactful to younger patients with SAH.

Oxidative Stress at the Crossroads of Aging, Stroke and Depression

Epidemiologic studies have shown that in the aging society, a person dies from stroke every 3 minutes and 42 seconds, and vast numbers of people experience depression around the globe. The high prevalence and disability rates of stroke and depression introduce enormous challenges to public health. Accumulating evidence reveals that stroke is tightly associated with depression, and both diseases are linked to oxidative stress (OS). This review summarizes the mechanisms of OS and OS-mediated pathological processes, such as inflammation, apoptosis, and the microbial-gut-brain axis in stroke and depression. Pathological changes can lead to neuronal cell death, neurological deficits, and brain injury through DNA damage and the oxidation of lipids and proteins, which exacerbate the development of these two disorders. Additionally, aging accelerates the progression of stroke and depression by overactive OS and reduced antioxidant defenses. This review also discusses the efficacy and safety of several antioxidants and antidepressants in stroke and depression. Herein, we propose a crosstalk between OS, aging, stroke, and depression, and provide potential therapeutic strategies for the treatment of stroke and depression.

Study protocol for SFX-01 after subarachnoid haemorrhage (SAS): a multicentre randomised double-blinded, placebo controlled trial

INTRODUCTION

Subarachnoid haemorrhage (SAH) from a ruptured cerebral aneurysm carries high morbidity and mortality. Despite huge advances in techniques to secure the aneurysm, there has been little progress in the treatment of the deleterious effects of the haemorrhage.Sulforaphane is an Nrf2 inducer with anti-oxidant and anti-inflammatory properties. It has been shown to improve clinical outcome in experimental models of SAH, but is unstable. SFX-01 (Evgen Pharma) is a novel composition comprised of synthetic sulforaphane stabilised within an α-cyclodextrin complex. On ingestion, the complex releases sulforaphane making SFX-01 an ideal vehicle for delivery of sulforaphane.

METHODS AND ANALYSIS

The objective of the study is to assess the safety, pharmacokinetics and efficacy of SFX-01. This is a prospective, multicentre, randomised, double-blind placebo-controlled trial in patients aged 18-80 years with aneurysmal subarachnoid haemorrhage in the previous 48 hours. 90 patients will be randomised to receive SFX-01 (300 mg) or placebo two times per day for up to 28 days.Safety will be assessed using blood tests and adverse event reporting.Pharmacokinetics will be assessed based on paired blood and cerebrospinal fluid (CSF) sulforaphane levels on day 7. A subgroup will have hourly samples taken during 6 hours post-dosing on days 1 and 7. Pharmacodynamics will be assessed by haptoglobin and malondialdehyde levels, and maximum flow velocity of middle cerebral artery will be measured by transcranial Doppler ultrasound.Clinical outcomes will be assessed at days 28, 90 and 180 with modified Rankin Scale, Glasgow Outcome Score, SAH Outcome Tool, Short Form-36, Brain Injury Community Rehabilitation Outcome Scales and Check List for Cognitive and Emotional consequences following stroke. MRI at 6 months including quantitative susceptibility mapping and volumetric T1 will measure iron deposition and cortical volume.Safety, CSF sulforaphane concentration and middle cerebral artery flow velocity will be primary outcomes and all others secondary.

ETHICS AND DISSEMINATION

Ethical approval was obtained from South Central Hampshire A committee. Outcomes of the trial will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT02614742.

Delayed Resolution of Cerebral Edema Is Associated With Poor Outcome After Nontraumatic Subarachnoid Hemorrhage

Background and Purpose- Global cerebral edema occurs in up to 57% of patients with subarachnoid hemorrhage (SAH) and is associated with prolonged hospital stay and poor outcome. Recently, admission brain edema was successfully graded using a simplified computed tomography-based semiquantitative score (subarachnoid hemorrhage early brain edema score [SEBES]). Longitudinal evaluation of the SEBES grade may discriminate patients with rapid and delayed edema resolution after SAH. Here, we aimed to describe the resolution of brain edema and to study the relationship between this radiographic biomarker and hospital course and outcome after SAH. Methods- For the current observational cohort study, computed tomography scans of 283 consecutive nontraumatic SAH patients admitted to the neurological intensive care unit of a tertiary hospital were graded based on the absence of visible sulci at 2 predefined brain tissue levels in each hemisphere (SEBES ranging from 0 to 4). A score of ≥3 was defined as high-grade SEBES. Multivariable regression models using generalized linear models were used to identify associated factors with delayed edema resolution based on the median time to resolution (SEBES ≤2) in SAH survivors. Results- Patients were 57 years old (interquartile range, 48-68) and presented with a median admission Hunt and Hess grade of 3 (interquartile range, 1-5). High-grade SEBES was common (106/283, 37%) and resolved within a median of 8 days (interquartile range, 4-15) in survivors (N=80). Factors associated with delayed edema resolution were early (<72 hours) hypernatremia (>150 mmol/L; adjusted odds ratio [adjOR], 4.88; 95% CI, 1.68-14.18), leukocytosis (>15 G/L; adjOR, 3.14; 95% CI, 1.24-8.77), hyperchloremia (>121 mmol/L; adjOR, 5.24; 95% CI, 1.64-16.76), and female sex (adjOR, 3.71; 95% CI, 1.01-13.64) after adjusting for admission Hunt and Hess grade and age. Delayed brain edema resolution was an independent predictor of worse functional 3-month outcome (adjOR, 2.52; 95% CI, 1.07-5.92). Conclusions- Our data suggest that repeated quantification of the SEBES can identify SAH patients with delayed edema resolution. Based on its' prognostic value as radiographic biomarker, the SEBES may be integrated in future trials aiming to improve edema resolution 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.

Neuroprotective Role of the Nrf2 Pathway in Subarachnoid Haemorrhage and Its Therapeutic Potential

The mechanisms underlying poor outcome following subarachnoid haemorrhage (SAH) are complex and multifactorial. They include early brain injury, spreading depolarisation, inflammation, oxidative stress, macroscopic cerebral vasospasm, and microcirculatory disturbances. Nrf2 is a global promoter of the antioxidant and anti-inflammatory response and has potential protective effects against all of these mechanisms. It has been shown to be upregulated after SAH, and Nrf2 knockout animals have poorer functional and behavioural outcomes after SAH. There are many agents known to activate the Nrf2 pathway. Of these, the actions of sulforaphane, curcumin, astaxanthin, lycopene, tert-butylhydroquinone, dimethyl fumarate, melatonin, and erythropoietin have been studied in SAH models. This review details the different mechanisms of injury after SAH including the contribution of haemoglobin (Hb) and its breakdown products. It then summarises the evidence that the Nrf2 pathway is active and protective after SAH and finally examines the evidence supporting Nrf2 upregulation as a therapy after SAH.

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.

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.

Leptin levels after subarachnoid haemorrhage are gender dependent

Background

Subarachnoid hemorrhage (SAH) is a neurological disease where the majority of the patients are critically ill. The adipokine leptin has in cerebral emergencies been related to severity of disease and to adverse outcome. The aim of this study was to examine leptin levels over time after SAH and associations to gender, age, body mass index, severity of disease, parenteral lipids, systemic organ failure and outcome.

Methods

Prospective observational study in 56 patients. Leptin was obtained 0–240 h after SAH, in 48 h intervals. Severity of disease was assessed with the Hunt and Hess score, organ failure with the sequential organ failure assessment score, and outcome with Glasgow outcome scale. Leptin levels in the SAH group were compared with controls from the same geographical area.

Results

At admission, Leptin was significantly higher in SAH patients compared to controls, both in female (28.6 ± 25.6 vs 13.0 ± 2.3 ng/mL, p = 0.001) and male patients (13.3 ± 8.4 vs 4.3 ± 0.7 ng/mL, p = 0.001). Leptin levels remained stable over time. Female patients had significantly higher leptin levels than male patients, and deceased female patients had higher leptin levels than female survivors (85.5 ± 20.5 vs 50.5 ± 34.6, n = 4/35, p < 0.05). Leptin levels did not differ between male survivors and non-survivors. Leptin levels were not associated with severity of disease, organ failure or parenteral lipids.

Conclusion

Leptin levels were significantly higher in both male and female patients compared to controls. Higher leptin levels were related to outcome and organ failure in women but not in men. When analysing leptin levels gender-related differences should be considered.

Advances in the understanding of delayed cerebral ischaemia after aneurysmal subarachnoid haemorrhage

Delayed cerebral ischaemia has been described as the single most important cause of morbidity and mortality in patients who survive the initial aneurysmal subarachnoid haemorrhage. Our understanding of the pathophysiology of delayed cerebral ischaemia is meagre at best and the calcium channel blocker nimodipine remains the only intervention to consistently improve functional outcome after aneurysmal subarachnoid haemorrhage. There is substantial evidence to support cerebral vessel narrowing as a causative factor in delayed cerebral ischaemia, but contemporary research demonstrating improvements in vessel narrowing has failed to show improved functional outcomes. This has encouraged researchers to investigate other potential causes of delayed cerebral ischaemia, such as early brain injury, microthrombosis, and cortical spreading depolarisation. Adherence to a common definition of delayed cerebral ischaemia is needed in order to allow easier assessment of studies using multiple different terms. Furthermore, improved recognition of delayed cerebral ischaemia would not only allow for faster treatment but also better assessment of interventions. Finally, understanding nimodipine's mechanism of action may allow us to develop similar agents with improved efficacy.

Effect of prolonged therapeutic hypothermia on intracranial pressure, organ function, and hospital outcomes among patients with aneurysmal subarachnoid hemorrhage

BACKGROUND

Global cerebral edema (GCE) with subsequent refractory intracranial hypertension complicates some cases of aneurysmal subarachnoid hemorrhage (aSAH), and typically is associated with poorer outcome. Treatment options for refractory intracranial pressure (ICP) cases are limited to decompressive hemicraniectomy (DHC) and targeted temperature management (TTM) with induced hypothermia (32-34 °C). No outcomes comparison between patients treated with either or both forms of refractory ICP therapy exists, and data on the effect of prolonged hypothermia on ICP and organ function among patients with aSAH are limited.

METHODS

This is a retrospective study of aSAH patients who underwent DHC and/or prolonged hypothermia (greater than 48 h) for refractory ICP (i.e., ICP >20 mmHg after osmotherapy) in the intensive care unit of a single, tertiary-care academic center.

RESULTS

Nineteen individuals with aSAH underwent TTM with or without DHC; sixteen patients underwent DHC alone. The patients in TTM group were younger (median age 44 years) than the DHC without TTM population (median age 60 years). TTM was started on median day 2 with a median duration of 7 days. There were no significant group differences in survival to discharge (59 % vs. 69 %) or in the mean modified Rankin score on follow-up (3.6 vs. 3.7), despite the TTM group having longer hospital length of stay (24 vs. 19 days, p = 0.03), longer duration of mechanical ventilation (20 vs. 9 days, p = 0.04), a higher cumulative fluid balance (12.8 vs. 5.1 L, p = 0.01), and higher APACHEII scores. The median maximal ICP decreased from 23.5 to 21 mmHg within 24 h of hypothermia initiation. There were no significant differences in other markers of end-organ function (respiratory, hematologic, renal, liver, and cardiac), infection rate, or adverse events between groups.

CONCLUSIONS

Use of prolonged TTM among aSAH patients with GCE and refractory ICP elevations is associated with a longer duration of mechanical ventilation but is not different in terms of neurological outcomes measured by modified Rankin score or organ function outcomes compared to patients who received DHC alone.

The pathophysiology and treatment of delayed cerebral ischaemia following subarachnoid haemorrhage

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

The role of the sonic hedgehog signaling pathway in early brain injury after experimental subarachnoid hemorrhage in rats

Previous studies have demonstrated that the sonic hedgehog (Shh) pathway plays a neuro-protective role. However, whether the Shh pathway is induced by subarachnoid hemorrhage (SAH) has not been investigated. We sought to investigate Shh activation in the cortex in the early stage of SAH, and assessed the effect of cyclopamine (a specific inhibitor of the Shh pathway) on Shh pathway regulation and evaluated the impact of cyclopamine on SAH. We found that the Shh pathway was up-regulated in the cortex after SAH, and that blocking the Shh pathway increased cell apoptosis. Early brain damages, including brain edema, blood-brain barrier impairment, and cortical apoptosis were significantly aggravated following with cyclopamine treatment compared with vehicle treatment. Our results suggest that the Shh pathway should be activated in the brain after SAH, and plays a beneficial role in SAH development, possibly by inhibiting cerebral oxidative stress through induction of antioxidant and detoxifying enzymes.

Brain edema formation correlates with perfusion deficit during the first six hours after experimental subarachnoid hemorrhage in rats

Background

Severe brain edema is observed in a number of patients suffering from subarachnoid hemorrhage (SAH). Little is known about its pathogenesis and time-course in the first hours after SAH. This study was performed to investigate the development of brain edema and its correlation with brain perfusion after experimental SAH.

Methods

Male Sprague–Dawley rats, randomly assigned to one of six groups (n = 8), were subjected to SAH using the endovascular filament model or underwent a sham operation. Animals were sacrificed 15, 30, 60, 180 or 360 minutes after SAH. Intracranial pressure (ICP), mean arterial blood pressure (MABP), cerebral perfusion pressure (CPP) and bilateral local cerebral blood flow (LCBF) were continuously measured. Brain water content (BWC) was determined by the wet/dry-weight method.

Results

After SAH, CPP and LCBF rapidly decreased. The decline of LCBF markedly exceeded the decline of CPP and persisted until the end of the observation period. BWC continuously increased. A significant correlation was observed between the BWC and the extent of the perfusion deficit in animals sacrificed after 180 and 360 minutes.

Conclusions

The significant correlation with the perfusion deficit after SAH suggests that the development of brain edema is related to the extent of ischemia and acute vasoconstriction in the first hours after SAH.