Fluid metabolic pathways after subarachnoid hemorrhage

Cannabidiol Alleviates Neurological Deficits After Traumatic Brain Injury by Improving Intracranial Lymphatic Drainage

Traumatic brain injury (TBI) persists as a substantial clinical dilemma, largely because of the absence of effective treatments. This challenge is exacerbated by the hindered clearance of intracranial metabolic byproducts and the continual accrual of deleterious proteins. The glymphatic system (GS) and meningeal lymphatic vessels (MLVs), key elements of the intracranial lymphatic network, play critical roles in the clearance of harmful substances. Cannabidiol (CBD) has shown promise in reducing metabolite overload and bolstering cognitive performance in various neurodegenerative diseases. The precise mechanisms attributing to its beneficial effects in TBI scenarios, however, are yet to be distinctly understood. Utilizing a fluid percussion injury paradigm, our research adopted a multifaceted approach, encompassing behavioral testing, immunofluorescence and immunohistochemical analyses, laser speckle imaging, western blot techniques, and bilateral cervical efferent lymphatic ligation. This methodology aimed to discern the influence of CBD on both neurological outcomes and intracranial lymphatic clearance in a murine TBI model. We observed that CBD administration notably ameliorated motor, memory, and cognitive functions, concurrently with a significant reduction in the concentration of phosphorylated tau protein and amyloid-β. In addition, CBD expedited the turnover and elimination of intracranial tracers, increased cerebral blood flow, and enhanced the efficacy of fluorescent tracer migration from MLVs to deep cervical lymph nodes (dCLNs). Remarkably, CBD treatment also induced a reversion in aquaporin-4 (AQP-4) polarization and curtailed neuroinflammatory indices. A pivotal discovery was that the surgical interruption of efferent lymphatic conduits in the neck nullified CBD's positive contributions to intracranial waste disposal and cognitive improvement, yet the anti-neuroinflammatory actions remained unaffected. These insights suggest that CBD may enhance intracranial metabolite clearance, potentially via the regulation of the intracranial lymphatic system, thereby offering neurofunctional prognostic improvement in TBI models. Our findings underscore the potential therapeutic applicability of CBD in TBI interventions, necessitating further comprehensive investigations and clinical validations to substantiate these initial conclusions.

Risk Factors for In-Hospital Seizures of Aneurysmal Subarachnoid Hemorrhage After Endovascular Treatment: A Real-World Study

BACKGROUND AND PURPOSE

The occurrence of in-hospital seizures for aneurysmal subarachnoid hemorrhage (aSAH) ranges from 3.7% to 15.2%, and seizures remain an important factor affecting patient prognosis. Therefore, the timely identification of patients at a higher risk for aSAH-associated seizures after endovascular treatment is of paramount importance. This study aims to analyze the risk factors for in-hospital seizures after endovascular treatment for aSAH.

METHODS

The study comprised 547 patients at 3 centers from January 2019 to September 2021. In the context of this study, 2 models were utilized: the first model involved no variable adjustment, while the second model included all potential confounders in the multivariate logistic regression analysis. Additionally, the dose-response relationship between biomarkers and seizure occurrence was assessed using restricted cubic spline.

RESULTS

Among these patients, 28 (5.1%) developed seizures during hospitalization. In Model 2, the modified Fisher score (adjusted odds ratio [OR]: 3.138, 95% confidence interval [CI]: 1.226-8.036), body mass index (adjusted OR: 0.852, 95% CI: 0.749-0.970), aspect ratio (adjusted OR: 0.264, 95% CI: 0.115-0.604), and aspartate transaminase (adjusted OR: 1.017, 95% CI: 1.001-1.035) were showed as factors contributing to an increased risk of aSAH-associated seizures.

CONCLUSIONS

Body mass index, aspartate transaminase, aspect ratio, modified Fisher scores, and Hunt-Hess scores were correlated with the formation of aSAH-associated seizures after endovascular treatment.

Influence of cerebrospinal fluid drainage in the first days after aneurysm rupture on the severity of early brain injury following aneurysmal subarachnoid hemorrhage

PURPOSE

Progressive cerebral edema with refractory intracranial hypertension (ICP) requiring decompressive hemicraniectomy (DHC) is a severe manifestation of early brain injury (EBI) after aneurysmal subarachnoid hemorrhage (aSAH). The purpose of the study was to investigate whether a more pronounced cerebrospinal fluid (CSF) drainage has an influence on cerebral perfusion pressure (CPP) and the extent of EBI after aSAH.

METHODS

Patients with aSAH and indication for ICP-monitoring admitted to our center between 2012 and 2020 were retrospectively included. EBI was categorized based on intracranial blood burden, persistent loss of consciousness, and SEBES (Subarachnoid Hemorrhage Early Brain Edema Score) score on the third day after ictus. The draining CSF and vital signs such as ICP and CPP were documented daily.

RESULTS

90 out of 324 eligible aSAH patients (28%) were included. The mean age was 54.2 ± 11.9 years. DHC was performed in 24% (22/90) of patients. Mean CSF drainage within 72 h after ictus was 168.5 ± 78.5 ml. A higher CSF drainage within 72 h after ictus correlated with a less severe EBI and a less frequent need for DHC (r=-0.33, p = 0.001) and with a higher mean CPP on day 3 after ictus (r = 0.2351, p = 0.02).

CONCLUSION

A more pronounced CSF drainage in the first 3 days of aSAH was associated with higher CPP and a less severe course of EBI and required less frequently a DHC. These results support the hypothesis that an early and pronounced CSF drainage may facilitate blood clearance and positively influence the course of EBI.

Endothelial EGLN3-PKM2 signaling induces the formation of acute astrocytic barrier to alleviate immune cell infiltration after subarachnoid hemorrhage

BACKGROUND

Most subarachnoid hemorrhage (SAH) patients have no obvious hematoma lesions but exhibit blood-brain barrier dysfunction and vasogenic brain edema. However, there is a few days between blood‒brain barrier dysfunction and vasogenic brain edema. The present study sought to investigate whether this phenomenon is caused by endothelial injury induced by the acute astrocytic barrier, also known as the glial limitans.

METHODS

Bioinformatics analyses of human endothelial cells and astrocytes under hypoxia were performed based on the GEO database. Wild-type, EGLN3 and PKM2 conditional knock-in mice were used to confirm glial limitan formation after SAH. Then, the effect of endothelial EGLN3-PKM2 signaling on temporal and spatial changes in glial limitans was evaluated in both in vivo and in vitro models of SAH.

RESULTS

The data indicate that in the acute phase after SAH, astrocytes can form a temporary protective barrier, the glia limitans, around blood vessels that helps maintain barrier function and improve neurological prognosis. Molecular docking studies have shown that endothelial cells and astrocytes can promote glial limitans-based protection against early brain injury through EGLN3/PKM2 signaling and further activation of the PKC/ERK/MAPK signaling pathway in astrocytes after SAH.

CONCLUSION

Improving the ability to maintain glial limitans may be a new therapeutic strategy for improving the prognosis of SAH patients.

Pathogenesis and management of low-pressure hydrocephalus: A narrative review

Patients diagnosed with low-pressure hydrocephalus typically present with enlarged ventricles and unusually low intracranial pressure, often measuring below 5 cmH2O or even below atmospheric pressure. This atypical presentation often leads to low recognition and diagnostic rates. The development of low-pressure hydrocephalus is believed to be associated with a decrease in the viscoelasticity of brain tissue or separation between the ventricular and subarachnoid spaces. Risk factors for low-pressure hydrocephalus include subarachnoid hemorrhage, aqueduct stenosis, prior cranial radiotherapy， ventricular shunting, and cerebrospinal fluid leaks. For potential low-pressure hydrocephalus, diagnostic criteria include neurological symptoms related to hydrocephalus, an Evans index >0.3 on imaging, ICP ≤ 5 cm H2O, symptom improvement with negative pressure drainage, and exclusion of ventriculomegaly caused by neurodegenerative diseases. The pathogenesis and pathophysiological features of low-pressure hydrocephalus differ significantly from other types of hydrocephalus, making it challenging to restore normal ventricular morphology through conventional drainage methods. The primary treatment options for low-pressure hydrocephalus involve negative pressure drainage and third ventriculostomy. With appropriate treatment, most patients can regain their previous neurological function. However, in most cases, permanent shunt surgery is still necessary. Low-pressure hydrocephalus is a rare condition with a high rate of underdiagnosis and mortality. Early identification and appropriate intervention are crucial in reducing complications and improving prognosis.

Therapeutic management of ischemic stroke

Stroke is the third leading cause of years lost due to disability and the second-largest cause of mortality worldwide. Most occurrences of stroke are brought on by the sudden occlusion of an artery (ischemic stroke), but sometimes they are brought on by bleeding into brain tissue after a blood vessel has ruptured (hemorrhagic stroke). Alteplase is the only therapy the American Food and Drug Administration has approved for ischemic stroke under the thrombolysis category. Current views as well as relevant clinical research on the diagnosis, assessment, and management of stroke are reviewed to suggest appropriate treatment strategies. We searched PubMed and Google Scholar for the available therapeutic regimes in the past, present, and future. With the advent of endovascular therapy in 2015 and intravenous thrombolysis in 1995, the therapeutic options for ischemic stroke have expanded significantly. A novel approach such as vagus nerve stimulation could be life-changing for many stroke patients. Therapeutic hypothermia, the process of cooling the body or brain to preserve organ integrity, is one of the most potent neuroprotectants in both clinical and preclinical contexts. The rapid intervention has been linked to more favorable clinical results. This study focuses on the pathogenesis of stroke, as well as its recent advancements, future prospects, and potential therapeutic targets in stroke therapy.

Monitoring of Perioperative Microcirculation Dysfunction by Near-Infrared Spectroscopy for Neurological Deterioration and Prognosis of Aneurysmal Subarachnoid Hemorrhage: An Observational, Longitudinal Cohort Study

INTRODUCTION

No evidence has established a direct causal relationship between early microcirculation disturbance after aneurysmal subarachnoid hemorrhage (aSAH) and neurological function prognosis, which is the key pathophysiological mechanism of early brain injury (EBI) in patients with aSAH.

METHODS

A total of 252 patients with aSAH were enrolled in the Neurosurgical Intensive Care Unit of Southwest Hospital between January 2020 and December 2022 and divided into the no neurological deterioration, early neurological deterioration, and delayed neurological deterioration groups. Indicators of microcirculation disorders in EBI included regional cerebral oxygen saturation (rSO2) measured by near-infrared spectroscopy (NIRS), brain oxygen monitoring, and other clinical parameters for evaluating neurological function and determining the prognosis of patients with aSAH.

RESULTS

Our data suggest that the rSO2 is generally lower in patients who develop neurological deterioration than in those who do not and that there is at least one time point in the population of patients who develop neurological deterioration where left and right cerebral hemisphere differences can be significantly monitored by NIRS. An unordered multiple-classification logistic regression model was constructed, and the results revealed that multiple factors were effective predictors of early neurological deterioration: reoperation, history of brain surgery, World Federation of Neurosurgical Societies (WFNS) grade 4-5, Fisher grade 3-4, SAFIRE grade 3-5, abnormal serum sodium and potassium levels, and reduced rSO2 during the perioperative period. However, for delayed neurological deterioration in patients with aSAH, only a history of brain surgery and perioperative RBC count were predictive indicators.

CONCLUSIONS

The rSO2 concentration in patients with neurological deterioration is generally lower than that in patients without neurological deterioration, and at least one time point in the population with neurological deterioration can be significantly monitored via NIRS. However, further studies are needed to determine the role of microcirculation and other predictive factors in the neurocritical management of EBI after aSAH, as these factors can reduce the incidence of adverse outcomes and mortality during hospitalization.

Risk Factors for In-Hospital Seizure and New-Onset Epilepsy in Coiling and Clipping Treatment of Aneurysmal Subarachnoid Hemorrhage

OBJECTIVE

To identify risk factors associated with in-hospital seizures and new-onset epilepsy in patients with aneurysmal subarachnoid hemorrhage (SAH) who underwent coiling embolization or clipping surgery.

METHODS

This retrospective descriptive study included 195 patients diagnosed with aneurysmal SAH and treated with coiling embolization or clipping surgery between January 2018 and June 2022.

RESULTS

Among the 195 patients meeting inclusion criteria, 9 experienced an onset seizure at the time of SAH. In-hospital seizures were observed in 33 patients, of which 24 were electrographic seizures detected in 24 patients with suspected subclinical seizures. After 12 months of follow-up, 11 patients met criteria for diagnosis of epilepsy. The incidence of epilepsy after discharge at 12 months was 2.41% in the coiling group and 8.03% in the clipping group. The risk of in-hospital seizures was significantly higher in the clipping group (P = 0.007), although the difference was not statistically significant after 12 months of follow-up (P = 0.121).

CONCLUSIONS

Epilepsy following aneurysmal SAH was relatively common. Clipping surgery and brain edema emerged as independent predictive factors for in-hospital seizures, while onset seizures and in-hospital seizures were identified as independent predictors of epilepsy during follow-up. Patients presenting with these risk factors may benefit from long-term electroencephalogram monitoring and should be considered for prophylactic antiepileptic drugs. Additionally, lumbar drainage proved effective in improving both early and late epileptic outcomes in the group with Fisher grades 3 and 4.

Perioperative complications of arteriovenous tirofiban administration versus oral dual antiplatelet therapy for stent-assisted embolization treated aneurysmal subarachnoid hemorrhage: A retrospective, controlled cohort analysis

BACKGROUND

Major perioperative complications of stent-assisted embolization treated for aneurysmal subarachnoid hemorrhage patients include the formation of thromboembolic events (TEs) and hemorrhagic events (HEs), for which antiplatelet protocols play a key role.

METHODS

We conducted a single-center retrospective analysis to compare the differences between arteriovenous tirofiban administration with traditional oral dual antiplatelet therapy (DAPT). A total of 417 consecutive patients were enrolled. General clinical characteristics, as well as the perioperative ischemic and hemorrhagic events, were retracted in digital documents. Logistic regression was conducted to identify both risk and protective factors of perioperative TEs and HEs.

RESULTS

Perioperative TEs occurred in 21 patients, with an overall perioperative TEs rate of approximately 5.04%; among these patients, the incidence of perioperative TEs in the tirofiban group was less than that in the DAPT group. Additionally, 66 patients developed perioperative HEs, with an incidence of approximately 15.83%; among these patients, the incidence of perioperative HEs was less than that in the DAPT group. No significant differences were seen between the two groups in terms of the mRS score at the time of discharge.

CONCLUSION

This study indicated that an improved perioperative antiplatelet drug tirofiban was an independent protective factor for perioperative TEs in stent-assisted embolization of ruptured intracranial aneurysms, but it did not impart an elevated risk of perioperative HEs and had no significant effects on the near-term prognosis of the patients.

Subdural Hygroma After Management of Ruptured Intracranial Aneurysms: Incidence, Associated Factors, Clinical Course, and Management Options

OBJECTIVE

To evaluate the incidence, associated factors, clinical course, and management options of subdural hygroma in patients treated for aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

From January 2013 until June 2022, 336 consecutive patients with aSAH underwent treatment in our center. No one patient was excluded from the study cohort. Computed tomography (CT) examinations were performed at admission, immediately after surgery and on the first postoperative day, and subsequently in case of any neurologic deterioration or, at least, once per week until discharge from the hospital. Thereafter, CT examinations were at the discretion of specialists in the rehabilitation facility, referring physicians, or neurosurgeons at the outpatient clinic.

RESULTS

The length of radiologic follow-up starting from CT at admission ranged from 1 to 3286 days (mean, 673 ± 895 days; median, 150 days). Subdural hygromas developed in 84 patients (25%). An average interval until this imaging finding from the initial CT examination was 25 ± 55 days (median, 8 days; range, 0-362 days). Evaluation in the multivariate model showed that patient age ≥72 years (P < 0.0001), cerebrospinal fluid (CSF) shunting (P < 0.0001), and microsurgical clipping of ruptured intracranial aneurysm (RIA; P < 0.0001) are independently associated with the development of subdural hygroma. In 54 of 84 cases (64%), subdural hygromas required observation only. Increase of the lesion size with (5 cases) or without (10 cases) appearance of midline shift was associated with patient age <72 years (P = 0.0398), decompressive craniotomy (P = 0.0192), and CSF shunting (P = 0.0009), whereas evaluation of these factors in the multivariate model confirmed independent association of only CSF shunting (P = 0.0003). Active management of subdural hygromas included adjustment of the shunt programmable valve opening pressure, cranioplasty, external subdural drainage, or their combination. Overall, during follow-up (mean, 531 ± 824 days; median, 119 days; range, 2-3285 days) after the start of observation or applied treatment, subdural hygromas showed either decrease (50 cases) or stabilization (34 cases) of their sizes, and no one lesion showed progression again.

CONCLUSIONS

The clinical course of subdural hygromas in patients treated for aSAH is generally favorable, but occasionally these lesions show progressive enlargement with or without the appearance of midline shift, which requires active management.

Functional effects of haemoglobin can be rescued by haptoglobin in an in vitro model of subarachnoid haemorrhage

During subarachnoid haemorrhage, a blood clot forms in the subarachnoid space releasing extracellular haemoglobin (Hb), which causes oxidative damage and cell death in surrounding tissues. High rates of disability and cognitive decline in SAH survivors are attributed to loss of neurons and functional connections during secondary brain injury. Haptoglobin sequesters Hb for clearance, but this scavenging system is overwhelmed after a haemorrhage. Whilst exogenous haptoglobin application can attenuate cytotoxicity of Hb in vitro and in vivo, the functional effects of sub-lethal Hb concentrations on surviving neurons and whether cellular function can be protected with haptoglobin treatment remain unclear. Here we use cultured neurons to investigate neuronal health and function across a range of Hb concentrations to establish the thresholds for cellular damage and investigate synaptic function. Hb impairs ATP concentrations and cytoskeletal structure. At clinically relevant but sub-lethal Hb concentrations, we find that synaptic AMPAR-driven currents are reduced, accompanied by a reduction in GluA1 subunit expression. Haptoglobin co-application can prevent these deficits by scavenging free Hb to reduce it to sub-threshold concentrations and does not need to be present at stoichiometric amounts to achieve efficacy. Haptoglobin itself does not impair measures of neuronal health and function at any concentration tested. Our data highlight a role for Hb in modifying synaptic function in surviving neurons, which may link to impaired cognition or plasticity after SAH and support the development of haptoglobin as a therapy for subarachnoid haemorrhage.

Metabolomics as a potential tool for monitoring patients with aneurysmal subarachnoid hemorrhage

Metabolomics has evolved into a particularly useful tool to study interactions between metabolites and serves as an aid in unraveling the complexity of entire metabolomes. Nonetheless, it is increasingly viewed as a methodology with practical applications in the clinical setting, where identifying and quantifying biomarkers of interest could prove useful for diagnostics. Starting from a concise overview of the most prominent analytical techniques employed in metabolomics, herein we present a review of its application in studies of brain metabolism and cerebrovascular diseases, paying most attention to its uses in researching aneurysmal subarachnoid hemorrhage. Both animal models and human studies are considered, and metabolites identified as potential biomarkers are highlighted.

Rethinking the initial changes in subarachnoid haemorrhage: Focusing on real-time metabolism during early brain injury

Over the last two decades, neurological researchers have uncovered many pathophysiological mechanisms associated with subarachnoid haemorrhage (SAH), with early brain injury and delayed cerebral ischaemia both contributing to morbidity and mortality. The current dilemma in SAH management inspired us to rethink the nature of the insult in SAH: sudden bleeding into the subarachnoid space and hypoxia due to disturbed cerebral circulation and increased intracranial pressure, generating exogenous stimuli and subsequent pathophysiological processes. Exogenous stimuli are defined as factors which the brain tissue is not normally exposed to when in the healthy state. Intersections of these initial pathogenic factors lead to secondary brain injury with related metabolic changes after SAH. Herein, we summarized the current understanding of efforts to monitor and analyse SAH-related metabolic changes to identify those precise pathophysiological processes and potential therapeutic strategies; in particular, we highlight the restoration of normal cerebrospinal fluid circulation and the normalization of brain-blood interface physiology to alleviate early brain injury and delayed neurological deterioration after SAH.

“Atypical” Mild Clinical Presentation in Elderly Patients With Ruptured Intracranial Aneurysm: Causes and Clinical Characteristics

Objective

Thunderclap-like severe headache or consciousness disturbance is the common “typical” clinical presentation after aneurysmal subarachnoid hemorrhage (aSAH); however, a slowly developing “atypical” clinical pattern, with mild headache, vomiting, or dizziness, is frequently noted in elderly patients. The aim of this study was to evaluate the clinical characteristics of this “atypical” subgroup, as well as related factors associated with the presence of these mild symptoms.

Methods

The data of 176 elderly patients (≥70 years old) with ruptured intracranial aneurysms (IAs) treated at our center from January 2016 to January 2020 were retrospectively collected and analyzed. The patients were divided into “typical” and “atypical” groups based on their initial and development of clinical symptoms after the diagnosis of aSAH. Intergroup differences were analyzed, and factors related to the presence of these two clinical patterns were explored through multiple logistic regression analyses.

Results

Despite significant admission delay (P &lt; 0.001) caused by mild initial symptoms with slow development, patients in the “atypical” group achieved better clinical prognosis, as indicated by a significantly higher favourable outcome ratio and lower death rate upon discharge and at different time points during the 1-year follow-up, than the “typical” group (P &lt; 0.05). Multiple logistic regression analysis revealed that modified Fisher grade III-IV (OR = 11.182, P = 0.003), brain atrophy (OR = 10.010, P = 0.001), a larger lesion diameter (OR = 1.287, P &lt; 0.001) and current smoking (OR = 5.728, P &lt; 0.001) were independently associated with the presence of “typical” symptoms. Aneurysms with wide necks (OR = 0.013, P &lt; 0.001) were independently associated with the presence of “atypical” symptoms.

Conclusions

“Atypical” presentations, with mild clinical symptoms and slow development, were commonly recorded in elderly patients after the onset of aSAH. Despite the prolonged admission delay, these “atypical” patients achieved better clinical outcomes than those with “typical” symptoms. Modified Fisher grade (III-IV), current smoking, brain atrophy and larger lesion diameter were factors predictive of “typical” symptoms, while aneurysms with wide necks were independently associated with “atypical” symptoms.

Treatment effect of DNA framework nucleic acids on diffuse microvascular endothelial cell injury after subarachnoid hemorrhage

Objectives

The purpose of this study was to investigate the treatment effect and molecular mechanism of tetrahedral framework nucleic acids (tFNAs), novel self‐assembled nucleic acid nanomaterials, in diffuse BMEC injury after SAH.

Materials and Methods

tFNAs were synthesized from four ssDNAs. The effects of tFNAs on SAH‐induced diffuse BMEC injury were explored by a cytotoxicity model induced by hemin, a breakdown product of hemoglobin, in vitro and a mouse model of SAH via internal carotid artery puncture in vivo. Cell viability assays, wound healing assays, transwell assays, and tube formation assays were performed to explore cellular function like angiogenesis.

Results

In vitro cellular function assays demonstrated that tFNAs could alleviate hemin‐induced injury, promote angiogenesis, and inhibit apoptosis in hemin cytotoxicity model. In vivo study using H&E and TEM results jointly indicated that the tFNAs attenuate the damage caused by SAH in situ, showing restored number of BMECs in the endothelium layer and more tight intercellular connectivity. Histological examination of SAH model animals confirmed the results of the in vitro study, as tFNAs exhibited treatment effects against diffuse BMEC injury in the cerebral microvascular bed.

Conclusions

Our study suggests the potential of tFNAs in ameliorating diffuse injury to BMECs after SAH, which laid theoretical foundation for the further study and use of these nucleic acid nanomaterials for tissue engineering vascularization.

Disturbed cerebral circulation and metabolism matters: A preface to the special issue "Stroke and Energy Metabolism": A preface to the special issue "Stroke and Energy Metabolism"

Stroke is a serious neurological disorder caused by blockage or rupture of cerebral blood vessels. Two main aims in acute stroke therapy include the restoration of cerebral blood flow in order to preserve energy supply to neurons and other brain cells, and minimizing neuronal loss. Maintenance of energy homeostasis in the brain drives neural network dynamics, which preserves normal brain function under physiological conditions. As such, cerebral energy homeostasis is a key target in stroke therapy. The various articles in this special issue highlight energy metabolism changes following stroke, including disturbed cerebral blood circulation, mitochondrial dysfunction, programmed neuronal cell death and cell-cell communication in brain metabolism. Collectively, this series of articles provides insight and presents new avenues for further research to improve the clinical management of stroke patients.