Venous system in acute brain injury: Mechanisms of pathophysiological change and function

Synchronous Superficial Middle Cerebral Vein Outflow Correlates Favorable Tissue Fate After Mechanical Thrombectomy for Acute Ischemic Stroke

RATIONALE AND OBJECTIVES

The purpose of this study was to determine the association between hemispheric synchrony in venous outflow at baseline and tissue fate after mechanical thrombectomy (MT) for acute ischemic stroke (AIS).

MATERIALS AND METHODS

A two-center retrospective analysis involving AIS patients who underwent MT was performed. The four cortical veins of interest include the superficial middle cerebral vein (SMCV), sphenoparietal sinus (SS), vein of Labbé (VOL), and vein of Trolard (VOT). Baseline computed tomography perfusion data were used to compare the following outflow parameters between the hemispheres: first filling time (△FFT), time to peak (△TTP) and total filling time (△TFT). Synchronous venous outflow was defined as △FFT = 0. Multivariable regression analyses were performed to evaluate the association of venous outflow synchrony with penumbral salvage, infarct growth, and intracranial hemorrhage (ICH) after MT.

RESULTS

A total of 151 patients (71.4 ± 13.2 years, 65.6% women) were evaluated. Patients with synchronous SMCV outflow demonstrated significantly greater penumbral salvage (41.3 mL vs. 33.1 mL, P = 0.005) and lower infarct growth (9.0 mL vs. 14.4 mL, P = 0.015) compared to those with delayed SMCV outflow. Higher △FFTSMCV (β = -1.44, P = 0.013) and △TTPSMCV (β = -0.996, P = 0.003) significantly associated with lower penumbral salvage, while higher △FFTSMCV significantly associated with larger infarct growth (β = 1.09, P = 0.005) and increased risk of ICH (odds ratio [OR] = 1.519, P = 0.047).

CONCLUSION

Synchronous SMCV outflow is an independent predictor of favorable tissue outcome and low ICH risk, and thereby carries the potential as an auxiliary radiological marker aiding the treatment planning of AIS patients.

Decrease in cortical vein opacification predicts outcome after aneurysmal subarachnoid hemorrhage

BACKGROUND

The pathophysiology of brain injury after aneurysmal subarachnoid hemorrhage (aSAH) remains incompletely understood. Cerebral venous flow patterns may be a marker of hemodynamic disruptions after aneurysm rupture. We hypothesized that a decrease in venous filling after aSAH would predict cerebral ischemia and poor outcome.

OBJECTIVE

To examine the hypotheses that venous filling as measured by the cortical venous opacification score (COVES) would (1) decrease after aSAH and (2) that decreased COVES would be associated with higher rates of hydrocephalus, vasospasm, delayed cerebral iscemia (DCI), and poor functional evaluation at outcome.

METHODS

In this retrospective observational cohort study of consecutive patients with aSAH admitted to our tertiary care center between 2016 and 2018, we measured the COVES at admission and at subsequent CT angiography (CTA). We collected clinical variables and compared hydrocephalus, vasospasm, DCI, and outcome at discharge in patients with decrease in COVES with patients with stable COVES.

RESULTS

A total of 22 patients were included in the analysis. COVES decreased from first CTA to second CTA in 11 (50%) patients, by an average of 1.1 points (P=0.01). Patients whose COVES decreased between admission and follow-up imaging were more likely to develop DCI (58% vs 0%, P=0.03) and have a poor outcome at discharge (100% vs 55%, P=0.03) than patients who had no change in COVES. aSAH severity was not associated with initial COVES, and there was no association between change in COVES and development of hydrocephalus or vasospasm.

CONCLUSIONS

Development of decreased venous filling on CTA is associated with poor outcome after aSAH. This association suggests that venous hemodynamics may be reflective of, or contribute to, the pathophysiological mechanisms of brain injury after aSAH. Larger prospective studies are necessary to substantiate our findings.

Cranial venous-outflow obstruction promotes neuroinflammation via ADAM17/solTNF-α/NF-κB pathway following experimental TBI

Traumatic brain injury (TBI) is a global public health problem. As an important cause of secondary injury, cerebrovascular reaction can cause secondary bleeding, venous sinus thrombosis, and malignant brain swelling. Recent clinical studies have confirmed that intracranial venous return disorder is closely related to the prognosis of patients, yet the specific molecular mechanism involved in this process is still unclear. This study used an acute subdural hematoma (ASDH) model with cranial venous outflow obstruction (CVO) to explore how CVO aggravates the pathological process after TBI, especially for inflammation and tissue damage. The results suggest that intracranial venous return disorder exacerbates neurological deficits and brain edema in rats with ASDH by aggravating the destruction of endothelial cell tight junctions (TJs) proteins and promoting the expression of inflammatory factors, the activation of microglia and expression of recombinant A disintegrin and metalloprotease 17 (ADAM17) as well as the secretion of solTNF-α, a soluble form of tumor necrosis factor-alpha (TNFα), which in turn increase IκB-α ((inhibitor of the transcription factor nuclear factor-κB) and NF-κB p65. Our study revealed a molecular basis of how CVO aggravates inflammation and tissue damage.

Arteriovenous cerebral blood flow correlation in moderate-to-severe traumatic brain injury: CT perfusion study

Introduction

The relationship between arterial and venous blood flow in moderate-to-severe traumatic brain injury (TBI) is poorly understood.

The research question

was to compare differences in perfusion computed tomography (PCT)-derived arterial and venous cerebral blood flow (CBF) in moderate-to-severe TBI as an indication of changes in cerebral venous outflow patterns referenced to arterial inflow.

Material and methods

Moderate-to-severe TBI patients (women 53; men 74) underwent PCT and were stratified into 3 groups: I (moderate TBI), II (diffuse severe TBI without surgery), and III (severe TBI after the surgery). Arterial and venous CBF were measured by PCT in both the internal carotid arteries (CBFica) and the confluence of upper sagittal, transverse, and straight sinuses (CBFcs).

Results

In group I, CBFica on the left and right sides were significantly correlated with each other (p < 0.0001) and with CBFcs (p = 0.048). In group II, CBFica on the left and right sides were also correlated (P < 0.0000001) but not with CBFcs. Intracranial pressure reactivity (PRx) and CBFcs were correlated (p = 0.00014). In group III, CBFica on the side of the removed hematoma was not significantly different from the opposite CBFica (P = 0.680) and was not correlated with CBFcs.

Discussion and conclusion

The increasing severity of TBI is accompanied by a rising uncoupling between the arterial and venous CBF in the supratentorial vessels suggesting a shifting of cerebral venous outflow.

Safety and clinical outcomes in endovascular treatment for symptomatic cerebral venous thrombosis: a single-center experience with meta-analysis

The role of mechanical thrombectomy (MT) in cerebral venous sinus thrombosis (CVT) is ambiguous. This study aims to share our experience with MT in CVT, supplemented by a meta-analysis on this treatment. All patients who had MT for CVT at our institution, between 2016 and 2021, were retrospectively reviewed for treatment indications, the technique used, success and complication rates, and clinical outcomes. A meta-analysis was performed for clinical and safety outcomes from published literature with > 10 patients. A total of 15 patients were included in this study. All had a venous hemorrhage or deteriorating despite anticoagulation. MT was performed using aspiration (with wide bore catheters) in 7 patients: aspiration with stent retriever in 5 and transjugular Fogarty-balloon thrombectomy in 3 patients. Adjunctive intra-sinus thrombolysis (IST) was used in 4 cases and venoplasty in 3. Technical success (restoring antegrade venous flow on arterial injection) was 100% with no procedure-related major complication. The direct transjugular approach was cheaper and faster. At 3-month follow-up, 86% of patients had good outcomes (MRS < 2). Meta-analysis of clinical and safety outcomes from 22 and 20 studies, respectively, demonstrated a positive association between MT and good outcomes as well as no significant association with hazardous periprocedural events. EVT via mechanical means for CVT is feasible in our series and meta-analysis. From our experience, trans-jugular Fogarty balloon embolectomy seems to be a potential cost-saving option, at least in a certain part of the world.

Evaluation of extent vs velocity of cortical venous filing in stroke outcome after endovascular thrombectomy

PURPOSE

Abnormal venous drainage may affect the prognosis of patients undergoing endovascular reperfusion therapy (ERT). Herein, time-resolved dynamic computed tomography arteriography (dCTA) was applied to evaluate the relationship between the velocity and extent of cortical venous filling (CVF), collateral status and outcomes.

METHODS

Thirty-five consecutive patients with acute anterior circulation occlusion who underwent ERT within 24 h of onset and successfully recanalized were enrolled. All patients underwent dCTA before ERT. Slow first or end of CVF was considered to occur when the time point of CVF appearance or disappearance on the affected side occurred after than that on the healthy side, whereas an equal CVF, a CVF reduced by ≤ 50%, or by > 50% on the affected side, were considered good, intermediate, and poor CVF extent, respectively.

RESULTS

Slow first CVF (29 patients, 82.8%), slow end of CVF (29, 85.7%), and intermediate extent of CVF (7, 20.0%) were not associated with collateral status or outcomes. Poor extent of CVF (6, 17.1%) was associated with poor collateral status, higher proportion of midline shift, larger final infarct volume, higher modified Rankin Scale (mRS) score at discharge, and higher proportion of in-hospital mortality. All patients with transtentorial herniation had poor extent of CVF, and those with poor CVF extent had an mRS score ≥ 3 at discharge.

CONCLUSION

Poor CVF extent, as assessed by dCTA, is a more accurate and specific marker than slow CVF to identify patients at high risk for poor outcomes after ERT.

Diagnostic and Therapeutic Challenges of Concurrent Intracranial Hemorrhage and Cerebral Venous Thrombosis in a Patient With Acute Lymphoblastic Leukemia: A Case Report and Literature Review

Cerebral venous sinus thrombosis (CVST) is a cerebrovascular condition due to the thrombosis of cerebral venous sinuses, leading to intracranial hemorrhage, increased intracranial pressure, focal deficit, seizure, toxic edema, encephalopathy, and death. The diagnosis and therapeutic approach of CVST remain challenging because of its highly nonspecific clinical presentation including headaches, seizures, focal neurologic deficits, and altered mental status, etc. Anticoagulation is the mainstay of CVST treatment and should be started as soon as the diagnosis is confirmed. Here, we present the case of a 34-year-old male construction worker who presented to the emergency department with a complaint of right chest wall pain and swelling. He was admitted to the hospital following a diagnosis of anterior chest wall abscess and mediastinitis. During hospitalization, his complete blood count revealed pancytopenia with blast cells, and bone marrow biopsy revealed 78.5% lymphoid blasts by aspirate differential count and hypercellular marrow (100%) with decreased hematopoiesis. He developed concurrent CVST and intracranial hemorrhage while receiving CALGB10403 (vincristine, daunorubicin, pegaspargase, prednisone) with intrathecal cytarabine induction chemotherapy for acute lymphoblastic leukemia (ALL). The patient failed two standard chemotherapy for ALL and achieved remission while on third-line chemotherapy with an anti-CD19 monoclonal antibody, blinatumomab. Although this patient had an MRI scan of the brain with multiple follow-up non-contrast CT scans, it was CT angiography that revealed CVST. This showed the diagnostic challenge in CVST, with CT and MRI venography having excellent sensitivity in diagnosing CVST. Risk factors for CVST in our patient were ALL and its intensive induction chemotherapy with pegaspargase.

Changes of Arterial and Venous Cerebral Blood Flow Correlation in Moderate-to-Severe Traumatic Brain Injury: A CT Perfusion Study

We compared differences in perfusion computed tomography (PCT)-derived arterial and venous cerebral blood flow (CBF) in moderate-to-severe traumatic brain injury (TBI) as an indication of changes in cerebral venous outflow patterns referenced to arterial inflow. Moderate-to-severe TBI patients (women 53; men 74) underwent PCT and were stratified into 3 groups: I (moderate TBI), II (diffuse severe TBI without surgery), and III (diffuse severe TBI after the surgery). Arterial and venous CBF was measured by PCT in both the middle cerebral arteries (CBFmca) and the upper sagittal sinus (CBFuss). In group I, CBFmca on the left and right sides were significantly correlated with each other (p < 0.0001) and with CBFuss (p = 0.048). In group II, CBFmca on the left and right sides were also correlated (p < 0.0000001) but not with CBFuss. Intracranial pressure reactivity (PRx) and CBFuss were correlated (p = 0.00014). In group III, CBFmca on the side of the removed hematoma was not significantly different from the opposite CBFmca (p = 0.680) and was not correlated with CBFuss. Conclusions: The increasing severity of TBI is accompanied by an impairment of the correlation between the arterial and venous CBF in the supratentorial vessels suggesting shifting in arterial and venous CBF in severe TBI associated with increased ICP reflected by PRx.

Molecular, Pathological, Clinical, and Therapeutic Aspects of Perihematomal Edema in Different Stages of Intracerebral Hemorrhage

Acute intracerebral hemorrhage (ICH) is a devastating type of stroke worldwide. Neuronal destruction involved in the brain damage process caused by ICH includes a primary injury formed by the mass effect of the hematoma and a secondary injury induced by the degradation products of a blood clot. Additionally, factors in the coagulation cascade and complement activation process also contribute to secondary brain injury by promoting the disruption of the blood-brain barrier and neuronal cell degeneration by enhancing the inflammatory response, oxidative stress, etc. Although treatment options for direct damage are limited, various strategies have been proposed to treat secondary injury post-ICH. Perihematomal edema (PHE) is a potential surrogate marker for secondary injury and may contribute to poor outcomes after ICH. Therefore, it is essential to investigate the underlying pathological mechanism, evolution, and potential therapeutic strategies to treat PHE. Here, we review the pathophysiology and imaging characteristics of PHE at different stages after acute ICH. As illustrated in preclinical and clinical studies, we discussed the merits and limitations of varying PHE quantification protocols, including absolute PHE volume, relative PHE volume, and extension distance calculated with images and other techniques. Importantly, this review summarizes the factors that affect PHE by focusing on traditional variables, the cerebral venous drainage system, and the brain lymphatic drainage system. Finally, to facilitate translational research, we analyze why the relationship between PHE and the functional outcome of ICH is currently controversial. We also emphasize promising therapeutic approaches that modulate multiple targets to alleviate PHE and promote neurologic recovery after acute ICH.

Intracranial Venous Alteration in Patients With Aneurysmal Subarachnoid Hemorrhage: Protocol for the Prospective and Observational SAH Multicenter Study (SMS)

Background

Arterial vasospasm has been ascribed as the responsible etiology of delayed cerebral infarction in patients with aneurysmal subarachnoid hemorrhage (aSAH), but other neurovascular structures may be involved. We present the protocol for a multicenter, prospective, observational study focused on analyzing morphological changes in cerebral veins of patients with aSAH.

Methods and Analysis

In a retrospective arm, we will collect head arterial and venous CT angiograms (CTA) of 50 patients with aSAH and 50 matching healthy controls at days 0–2 and 7–10, comparing morphological venous changes. A multicenter prospective observational study will follow. Patients aged ≥18 years of any gender with aSAH will be enrolled at 9 participating centers based on the predetermined eligibility criteria. A sample size of 52 aSAH patients is expected, and 52 healthy controls matched per age, gender, and comorbidities will be identified. For each patient, sequential CTA will be conducted upon admission (day 0–2), at 7–10 days, and at 14–21 days after aSAH, evaluating volumes and morphology of the cerebral deep veins and main cortical veins. One specialized image collecting center will analyze all anonymized CTA scans, performing volumetric calculation of targeted veins. Morphological venous changes over time will be evaluated using the Dice coefficient and the Jaccard index and scored using the Boeckh–Behrens system. Morphological venous changes will be correlated to clinical outcomes and compared between patients with aSAH and healthy-controls, and among groups based on surgical/endovascular treatments for aSAH.

Ethics and Dissemination

This protocol has been approved by the ethics committee and institutional review board of Ethikkommission, SALK, Salzburg, Austria, and will be approved at all participating sites. The study will comply with the Declaration of Helsinki. Written informed consent will be obtained from all enrolled patients or their legal tutors. We will present our findings at academic conferences and peer-reviewed journals.

Approved Protocol Version and Registration

Version 2, 09 June 2021.

Canine Intracranial Venous System: A Review

The intracranial venous system (ICVS) represents in mammals a complex three-dimensional structure, which provides not only for adequate brain perfusion, but has also a significant impact on: cerebrospinal fluid (CSF) resorption, maintaining of the intracranial pressure (ICP), and brain thermoregulation. An intimate understanding of the anatomy and physiology of ICVS is fundamental for neurological diagnostics, selection of therapeutic options, and success of neurosurgical procedures in human and veterinary medicine. Since the intracranial interventions in dogs are recently performed more frequently than twenty or thirty years ago, the authors decided to review and report on the basic knowledge regarding the complex topic of morphology and function of the canine ICVS. The research strategy involved an NCBI/NLM, PubMed/MED-LINE, and Clarivate Analytics Web of Science search from January 1, 1960, to December 31, 2021, using the terms “canine dural venous sinuses” and “intracranial venous system in dogs” in the English language literature; also references from selected papers were scanned and relevant articles included.

Attenuation of tonic inhibition prevents chronic neurovascular impairments in a Thy1-ChR2 mouse model of repeated, mild traumatic brain injury

Rationale: Mild traumatic brain injury (mTBI), the most common type of brain trauma, frequently leads to chronic cognitive and neurobehavioral deficits. Intervening effectively is impeded by our poor understanding of its pathophysiological sequelae.

Methods: To elucidate the long-term neurovascular sequelae of mTBI, we combined optogenetics, two-photon fluorescence microscopy, and intracortical electrophysiological recordings in mice to selectively stimulate peri-contusional neurons weeks following repeated closed-head injury and probe individual vessel's function and local neuronal reactivity.

Results: Compared to sham-operated animals, mTBI mice showed doubled cortical venular speeds (115 ± 25%) and strongly elevated cortical venular reactivity (53 ± 17%). Concomitantly, the pericontusional neurons exhibited attenuated spontaneous activity (-57 ± 79%) and decreased reactivity (-47 ± 28%). Post-mortem immunofluorescence revealed signs of peri-contusional senescence and DNA damage, in the absence of neuronal loss or gliosis. Alteration of neuronal and vascular functioning was largely prevented by chronic, low dose, systemic administration of a GABA-A receptor inverse agonist (L-655,708), commencing 3 days following the third impact.

Conclusions: Our findings indicate that repeated mTBI leads to dramatic changes in the neurovascular unit function and that attenuation of tonic inhibition can prevent these alterations. The sustained disruption of the neurovascular function may underlie the concussed brain's long-term susceptibility to injury, and calls for development of better functional assays as well as of neurovascularly targeted interventions.

Evaluating the Velocity and Extent of Cortical Venous Filling in Patients With Severe Middle Cerebral Artery Stenosis or Occlusion

Objective: To investigate the velocity and extent of cortical venous filling (CVF) and its association with clinical manifestations in patients with severe stenosis or occlusion of the middle cerebral artery (MCA) using dynamic computed tomography angiography (CTA). Methods: Fifty-eight patients (36 symptomatic and 22 asymptomatic) with severe unilateral stenosis (≥70%) or occlusion of the MCA M1 segment who underwent dynamic CTA were included. Collateral status, antegrade flow, and CVF of each patient were observed using dynamic CTA. Three types of cortical veins were selected to observe the extent of CVF, and the absence of CVF (CVF-) was recorded. Based on the appearance of CVF in the superior sagittal sinus, instances of CVF, including early (CVF₁), peak (CVF₂), and late (CVF₃) venous phases, were recorded. The differences in CVF times between the affected and contralateral hemispheres were represented as rCVFs, and CVF velocity was defined compared to the median time of each rCVF. Results: All CVF times in the affected hemisphere were longer than those in the contralateral hemisphere (p < 0.05). Patients with symptomatic MCA stenosis had more ipsilateral CVF- (p = 0.02) and more delayed CVF at rCVF₂ and rCVF₂₁ (rCVF₂-rCVF₁) (p = 0.03 and 0.001, respectively) compared to those with asymptomatic MCA stenosis. For symptomatic patients, fast CVF at rCVF₂₁ was associated with poor collateral status (odds ratio [OR] 6.42, 95% confidence interval [CI] 1.37-30.05, p = 0.02), and ipsilateral CVF- in two cortical veins was associated with poor 3-month outcomes (adjusted OR 0.025, 95% CI 0.002-0.33, p = 0.005). Conclusions: Complete and fast CVF is essential for patients with symptomatic MCA stenosis or occlusion. The clinical value of additional CVF assessment should be explored in future studies to identify patients with severe MCA stenosis or occlusion at a higher risk of stroke occurrence and poor recovery.

Thalamic venous infarction from trauma mimicking a glioma

Traumatic brain injuries (TBI) are commonly associated with motor vehicle accidents. Neuroimaging plays a crucial role in the initial management of TBIs. We present a case of a TBI related to a motor vehicle accident in an 18-year-old woman. Initial brain imaging revealed significant traumatic injuries and an enhancing mass, without restricted diffusion, in the thalamus favored to be a thalamic glioma. Subsequent imaging revealed resolution of enhancement of the thalamic lesion and reduction in size. On review of the original imaging, it was determined that the thalamic lesion was related to a tear and partial thrombosis of a large thalamic vein resulting in infarction and hemorrhage.

Cerebrovascular pathophysiology of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) remains a serious cerebrovascular disease. Even if SAH patients survive the initial insults, delayed cerebral ischemia (DCI) may occur at 4 days or later post-SAH. DCI is characteristics of SAH, and is considered to develop by blood breakdown products and inflammatory reactions, or secondary to early brain injury, acute pathophysiological events that occur in the brain within the first 72 hours of aneurysmal SAH. The pathology underlying DCI may involve large artery vasospasm and/or microcirculatory disturbances by microvasospasm, microthrombosis, dysfunction of venous outflow and compression of microvasculature by vasogenic or cytotoxic tissue edema. Recent clinical evidence has shown that large artery vasospasm is not the only cause of DCI, and that both large artery vasospasm-dependent and -independent cerebral infarction causes poor outcome. Animal studies suggest that mechanisms of vasospasm may differ between large artery and arterioles or capillaries, and that many kinds of cells in the vascular wall and brain parenchyma may be involved in the pathogenesis of microcirculatory disturbances. The impairment of the paravascular and glymphatic systems also may play important roles in the development of DCI. As pathological mediators for DCI, glutamate and several matricellular proteins have been investigated in addition to inflammatory molecules. Glutamate is involved in excitotoxicity contributing to cortical spreading ischemia and epileptic activity-related events. Microvascular dysfunction is an attractive mechanism to explain the cause of poor outcomes independently of large cerebral artery vasospasm, but needs more studies to clarify the pathophysiologies or mechanisms and to develop a novel therapeutic strategy.

Visualization of cortical cerebral blood flow dynamics during craniotomy in acute subdural hematoma using laser speckle imaging in a rat model

Mass evacuation with decompressive craniotomy is considered a standard intervention for acute subdural hematoma (ASDH). However, hemispheric swelling complicates the intraoperative and postoperative management of ASDH patients, and previous studies have revealed that this approach can damage ischemic/reperfusion (I/R) injury. Few studies have focused on the cerebrovascular response following traumatic brain injury (TBI). To characterize the relative cerebral blood flow (rCBF) before and after removal of the hematoma, rats were injured by a subdural infusion of 400 μL of venous blood or paraffin oil. MRI scans were performed. Then, we monitored cortical rCBF during hematoma removal in real time using laser speckle imaging (LSCI) in ASDH rats. The CBF of arteriovenous and capillary regions were quantified and normalized to their own baseline values via a custom algorithm. In the sham group, the cortical CBF was higher post-craniotomy than pre-craniotomy. However, in the hematoma injection group, the CBF of arteries and capillaries was higher while the venous CBF was lower post-craniotomy than pre-craniotomy. The difference in the changes in vein CBF that occurred between the two groups was statistically significant. The three components of the vascular system showed heterogeneous responses to craniotomy, which may be the basis for secondary brain injury.

Argatroban Increased the Basal Vein Drainage and Improved Outcomes in Acute Paraventricular Ischemic Stroke Patients

Background

Since venous drainage in acute arterial ischemic stroke has not been thoroughly researched, we evaluate the effect of argatroban, a selective direct thrombin inhibitor, as a therapy to increase the rate of basal vein Rosenthal (BVR) drainage and improve patients’ post-stroke outcomes.

Material/Methods

In this multicenter clinical trial, 60 eligible patients at 4.5 to 48 hours after the stroke onset were recruited. After being randomly allocated into 2 groups, they were treated with standard therapy either alone or with argatroban.

Results

Compared to the contralateral brain hemisphere, the mean flow velocity (MFV) in BVR drainage was significantly reduced in the stroke-afflicted ipsilateral hemisphere. After treatment with argatroban for 7 days, the MFV from BVR of the ipsilateral hemisphere in the argatroban treated group was significantly increased when compared to the control group. At 90 days after the onset of stroke, the MFV of BVR in the ipsilateral hemisphere was similar in both groups. Compared with controls, the argatroban-treated patients had smaller lesions from baseline to 7 days. Argatroban also improved National Institutes of Health Stroke Scale (NIHSS) scores on day 7 after the onset of stroke. Furthermore, the argatroban group’s neurological functions were superior to those of their untreated counterparts after 90 days. No difference was found in the incidence of adverse reactions between the 2 groups.

Conclusions

These observations indicate that vein drainage change may contribute to the acute phase of brain edema and the outcomes of ischemic stroke patients.

Clinical Trial Registration

URL-http://www.chictr.org

Unique identifier: ChiCTR-IPR-16008663

Spaceflight associated neuro-ocular syndrome (SANS) and the neuro-ophthalmologic effects of microgravity: a review and an update

Prolonged microgravity exposure during long-duration spaceflight (LDSF) produces unusual physiologic and pathologic neuro-ophthalmic findings in astronauts. These microgravity associated findings collectively define the “Spaceflight Associated Neuro-ocular Syndrome” (SANS). We compare and contrast prior published work on SANS by the National Aeronautics and Space Administration’s (NASA) Space Medicine Operations Division with retrospective and prospective studies from other research groups. In this manuscript, we update and review the clinical manifestations of SANS including: unilateral and bilateral optic disc edema, globe flattening, choroidal and retinal folds, hyperopic refractive error shifts, and focal areas of ischemic retina (i.e., cotton wool spots). We also discuss the knowledge gaps for in-flight and terrestrial human research including potential countermeasures for future study. We recommend that NASA and its research partners continue to study SANS in preparation for future longer duration manned space missions.

Cerebral venous circulation changes caused by aneurysmal subarachnoid hemorrhage

BACKGROUND

The aneurysmal subarachnoid hemorrhage (aSAH) is an acute severe hemorrhagic stroke with high morbidity and mortality with poor prognosis.

OBJECTIVE

This study aims to analyze the changes of cerebral venous circulation in patients with aneurysmal subarachnoid hemorrhage by digital subtraction angiography (DSA).

MATERIALS AND METHODS

Totally, 57 patients with aSAH, 48 patients with unruptured aneurysms, and 45 patients without aneurysms (control group) were enrolled. The microvascular cerebral circulation time (mCCT), venous cerebral circulation time (vCCT), cerebral arterioles and cortical veins were analyzed by DSA.

RESULTS

There were changes of cerebral microvessels and cortical veins in patients with aSAH. The mCCT (6.15±1.37 s) and vCCT (2.79±0.34 s) of aSAH patients significantly increased compared with control patients (3.74±0.50 s; 2.64±0.32 s) (P < 0.05). However, the mCCT increased more compared with vCCT in aSAH patients (P < 0.001), while the vCCT increased more compared with mCCT in severe aSAH cases (P < 0.01). There was no significant difference in mCCT and vCCT between patients with unruptured aneurysms and controls (P = 0.131; P = 0.621).

CONCLUSIONS

The mCCT increases in acute aSAH patients within 72 hours and vCCT increases in severe aSAH cases.

Real-time quantitative monitoring of cerebral blood flow by laser speckle contrast imaging after cardiac arrest with targeted temperature management

Brain injury is the main cause of mortality and morbidity after cardiac arrest (CA). Changes in cerebral blood flow (CBF) after reperfusion are associated with brain injury and recovery. To characterize the relative CBF (rCBF) after CA, 14 rats underwent 7 min asphyxia-CA and were randomly treated with 6 h post-resuscitation normothermic (36.5-37.5℃) or hypothermic- (32-34℃) targeted temperature management (TTM) (N = 7). rCBF was monitored by a laser speckle contrast imaging (LSCI) technique. Brain recovery was evaluated by neurologic deficit score (NDS) and quantitative EEG - information quantity (qEEG-IQ). There were regional differences in rCBF among veins of distinct cerebral areas and heterogeneous responses among the three components of the vascular system. Hypothermia immediately following return of spontaneous circulation led to a longer hyperemia duration (19.7 ± 1.8 vs. 12.7 ± 0.8 min, p < 0.01), a lower rCBF (0.73 ± 0.01 vs. 0.79 ± 0.01; p < 0.001) at the hypoperfusion phase, a better NDS (median [25th-75th], 74 [61-77] vs. 49 [40-77], p < 0.01), and a higher qEEG-IQ (0.94 ± 0.02 vs. 0.77 ± 0.02, p < 0.001) compared with normothermic TTM. High resolution LSCI technique demonstrated hypothermic TTM extends hyperemia duration, delays onset of hypoperfusion phase and lowered rCBF, which is associated with early restoration of electrophysiological recovery and improved functional outcome after CA.

Multispectral imaging of cortical vascular and hemodynamic responses to a shock wave: observation of spreading depolarization and oxygen supply-demand mismatch

Blast-induced traumatic brain injury has been a recent major concern in neurotraumatology. However, its pathophysiology and mechanism are not understood partly due to insufficient information on the brain pathophysiology during/immediately after shock wave exposure. We transcranially applied a laser-induced shock wave (LISW, ∼19  Pa  ·  s) to the left frontal region in a rat and performed multispectral imaging of the ipsilateral cortex through a cranial window (n  =  4). For the spectral data obtained, we conducted multiple regression analysis aided by Monte Carlo simulation to evaluate vascular diameters, regional hemoglobin concentration (rCHb), tissue oxygen saturation (StO2), oxygen extraction fraction, and light-scattering signals as a signature of cortical spreading depolarization (CSD). Immediately after LISW exposure, rCHb and StO2 were significantly decreased with distinct venular constriction. CSD was then generated and was accompanied by distinct hyperemia/hyperoxemia. This was followed by oligemia with arteriolar constriction, but it soon recovered (within ∼20  min). However, severe hypoxemia was persistently observed during the post-CSD period (∼1  h). These observations indicate that inadequate oxygen supply and/or excessive oxygen consumption continued even after blood supply was restored in the cortex. Such a hypoxemic state and/or a hypermetabolic state might be associated with brain damage caused by a shock wave.

Refocusing Neuroprotection in Cerebral Reperfusion Era: New Challenges and Strategies

Pathophysiological processes of stroke have revealed that the damaged brain should be considered as an integral structure to be protected. However, promising neuroprotective drugs have failed when translated to clinical trials. In this review, we evaluated previous studies of neuroprotection and found that unsound patient selection and evaluation methods, single-target treatments, etc., without cerebral revascularization may be major reasons of failed neuroprotective strategies. Fortunately, this may be reversed by recent advances that provide increased revascularization with increased availability of endovascular procedures. However, the current improved effects of endovascular therapy are not able to match to the higher rate of revascularization, which may be ascribed to cerebral ischemia/reperfusion injury and lacking of neuroprotection. Accordingly, we suggest various research strategies to improve the lower therapeutic efficacy for ischemic stroke treatment: (1) multitarget neuroprotectant combinative therapy (cocktail therapy) should be investigated and performed based on revascularization; (2) and more efforts should be dedicated to shifting research emphasis to establish recirculation, increasing functional collateral circulation and elucidating brain–blood barrier damage mechanisms to reduce hemorrhagic transformation. Therefore, we propose that a comprehensive neuroprotective strategy before and after the endovascular treatment may speed progress toward improving neuroprotection after stroke to protect against brain injury.

Collateral pial circulation relates to the degree of brain edema on CT 24 hours after ischemic stroke

Background Cerebral edema is frequent in patients with acute ischemic stroke (AIS) who undergo reperfusion therapy and is associated with high mortality. The impact of collateral pial circulation (CPC) status on the development of edema has not yet been determined. Methods We studied consecutive patients with AIS and documented M1-middle cerebral artery (MCA) and/or distal internal carotid artery (ICA) occlusion who underwent reperfusion treatment. Edema was graded on the 24-hour non-contrast computed tomography (NCCT) scan. CPC was evaluated at the acute phase (≤6 hours) by transcranial color-coded Doppler, angiography and/or CT angiography. We performed an ordinal regression model for the effect of CPC on cerebral edema, adjusting for age, baseline National Institutes of Health Stroke Scale, Alberta Stroke Program Early Computed Tomography Score (ASPECTS) on admission, NCCT, parenchymal hemorrhagic transformation at 24 hours and complete recanalization at six hours. Results Among the 108 patients included, 49.1% were male and mean age was 74.2 ± 11.6 years. Multivariable analysis showed a significant association between cerebral edema and CPC status (OR 0.22, 95% CI 0.08-0.59, p = 0.003), initial ASPECTS (OR 0.72, 95% CI 0.57-0.92, p = 0.007) and parenchymal hemorrhagic transformation (OR 23.67, 95% CI 4.56-122.8, p < 0.001). Conclusions Poor CPC is independently associated with greater cerebral edema 24 hours after AIS in patients who undergo reperfusion treatment.

Cerebral venous collaterals: A new fort for fighting ischemic stroke?

Stroke therapy has entered a new era highlighted by the use of endovascular therapy in addition to intravenous thrombolysis. However, the efficacy of current therapeutic regimens might be reduced by their associated adverse events. For example, over-reperfusion and futile recanalization may lead to large infarct, brain swelling, hemorrhagic complication and neurological deterioration. The traditional pathophysiological understanding on ischemic stroke can hardly address these occurrences. Accumulating evidence suggests that a functional cerebral venous drainage, the major blood reservoir and drainage system in brain, may be as critical as arterial infusion for stroke evolution and clinical sequelae. Further exploration of the multi-faceted function of cerebral venous system may add new implications for stroke outcome prediction and future therapeutic decision-making. In this review, we emphasize the anatomical and functional characteristics of the cerebral venous system and illustrate its necessity in facilitating the arterial infusion and maintaining the cerebral perfusion in the pathological stroke content. We then summarize the recent critical clinical studies that underscore the associations between cerebral venous collateral and outcome of ischemic stroke with advanced imaging techniques. A novel three-level venous system classification is proposed to demonstrate the distinct characteristics of venous collaterals in the setting of ischemic stroke. Finally, we discuss the current directions for assessment of cerebral venous collaterals and provide future challenges and opportunities for therapeutic strategies in the light of these new concepts.

MAVEN: An Algorithm for Multi-Parametric Automated Segmentation of Brain Veins From Gradient Echo Acquisitions

Cerebral vein analysis provides a chance to study, from an unusual viewpoint, an entire class of brain diseases, including neurodegenerative disorders and traumatic brain injuries. Manual segmentation approaches can be used to assess vascular anatomy, but they are observer-dependent and time-consuming; therefore, automated approaches are desirable, as they also improve reproducibility. In this paper, a new, fully automated algorithm, based on structural, morphological, and relaxometric information, is proposed to segment the entire cerebral venous system from MR images. The algorithm for multi-parametric automated segmentation of brain VEiNs (MAVEN) is based on a combined investigation of multi-parametric information that allows for rejection of false positives and detection of thin vessels. The method is tested on gradient echo brain data sets acquired at 1.5, 3, and 7 T. It is compared to previous methods against manual segmentation, and its inter-scan reproducibility is assessed. The achieved accuracy and reproducibility are good, meaning that MAVEN outperforms previous methods on both quantitative and qualitative analyses. It is usable at all the field strengths explored, showing comparable accuracy scores, with no need for algorithm parameter adjustments, and thus, it is a promising candidate for the characterization of the venous tree topology.

Blood-filled cerebrospinal fluid-enhanced pericyte microvasculature contraction in rat retina: A novel in vitro study of subarachnoid hemorrhage

Previously, it was widely accepted that the delayed ischemic injury and poor clinical outcome following subarachnoid hemorrhage (SAH) was caused by cerebral vasospasm. This classical theory was challenged by a clazosentan clinical trial, which failed to improve patient outcome, despite reversing angiographic vasospasm. One possible explanation for the results of this trial is the changes in microcirculation following SAH, particularly in pericytes, which are the primary cell type controlling microcirculation in the brain parenchyma. However, as a result of technical limitations and the lack of suitable models, there was no direct evidence of microvessel dysfunction following SAH. In the present study, whole-mount retinal microvasculature has been introduced to study microcirculation in the brain following experimental SAH in vitro. Artificial blood-filled cerebrospinal fluid (BSCF) was applied to the retinal microvasculature to test the hypothesis that the presence of subarachnoid blood affects the contractile properties of the pericytes containing cerebral microcirculation during the early phase of SAH. It was observed that BCSF induced retina microvessel contraction and that this contraction could be resolved by BCSF wash-out. Furthermore, BCSF application accelerated pericyte-populated collagen gel contraction and increased the expression of α-smooth muscle actin. In addition, BCSF induced an influx of calcium in cultured retinal pericytes. In conclusion, the present study demonstrates increased contractility of retinal microvessels and pericytes in the presence of BCSF in vitro. These findings suggest that pericyte contraction and microvascular dysfunction is induced following SAH, which could lead to greater susceptibility to SAH-induced ischemia.

Original Research: Feasibility and safety of two surgical techniques for the development of an animal model of jugular vein occlusion

To date, no studies have explored the effect of abnormal cerebral venous circulation on brain disorders, whereas many studies have investigated neurodegenerative brain anomalies associated with arterial diseases. The aim of our study was to demonstrate the feasibility of different surgical techniques to induce venous obstruction of cerebral brain drainage. Six C57/black mice underwent bilateral occlusion of the external jugular vein (group EJV), six underwent bilateral occlusion of the internal jugular vein (group IJV), and six underwent bilateral occlusion of both the EJV and the IJV (group EJV/IJV). Within each group, the interruption of blood flow was obtained via monopolar electro-coagulation (ME) in three mice and via surgical ligation (SL) in the remaining three mice. A "sham group" of two mice was used as the control. High-frequency ultrasound (HFUS) was used to detect the absence of blood flow in the examined vessel. The ME procedure led to successful results in two of nine (22%) mice, one in the EJV group, one in the EJV/IJV group, and zero in the IJV group, and 4 of 18 (22%) mice when considering individual veins (i.e., total number of EJVs and IJVs occluded). The SL procedure was successful in two of three (67%) mice in the EJV group, in three of three (100%) mice in the IJV and in three of four (75%) mice in the EJV/IJV group. Therefore, the overall success rate was 8/10 (80%) when considering mice, and 20/26 (77%) when considering individual veins. The monopolar electro-coagulation method exhibited a high mortality due to cardiorespiratory arrest, while the results of the bilateral surgical ligation of EJVs and IJVs show that it is technically feasible and safe.

Hemoglobin induced NO/cGMP suppression Deteriorate Microcirculation via Pericyte Phenotype Transformation after Subarachnoid Hemorrhage in Rats

Subarachnoid hemorrhage (SAH) usually results from ruptured aneurysm, but how leaked hemoglobin regulates the microcirculation in the pathophysiology of early brain injury after SAH is still unclear. In the present study, we sought to investigate the role and possible mechanism of hemoglobin induced pericyte phenotype transformation in the regulation of microcirculation after SAH. Endovascular perforation SAH rat model, brain slices and cultured pericytes were used, and intervened with endothelial nitric oxide synthase (eNOS) antagonist L-NNA and its agonist scutellarin, hemoglobin, DETA/NO (nitric oxide(NO) donor), PITO (NO scavenger), 8-Br-cGMP (cGMP analog). We found modulating eNOS regulated pericyte α-SMA phenotype transformation, microcirculation, and neurological function in SAH rats. Modulating eNOS also affected eNOS expression, eNOS activity and NO availability after SAH. In addition, we showed hemoglobins penetrated into brain parenchyma after SAH. And hemoglobins significantly reduced the microvessel diameters at pericyte sites, due to the effects of hemoglobin inducing α-SMA expressions in cultured pericytes and brain slices via inhibiting NO/cGMP pathway. In conclusion, pericyte α-SMA phenotype mediates acute microvessel constriction after SAH possibly by hemoglobin suppressing NO/cGMP signaling pathway. Therefore, by targeting the eNOS and pericyte α-SMA phenotype, our present data may shed new light on the management of SAH patients.

Cortical Venous Filling on Dynamic Computed Tomographic Angiography: A Novel Predictor of Clinical Outcome in Patients With Acute Middle Cerebral Artery Stroke

BACKGROUND AND PURPOSE

Venous flow in the downstream territory of an occluded artery may influence patient prognosis after ischemic stroke. Our aim was to study cortical venous filling (CVF) in a time-resolved manner with dynamic computed tomographic angiography and to assess the relationship with clinical outcome.

METHODS

Patients with a proximal middle cerebral artery occlusion underwent noncontrast CT and whole-brain CT perfusion/dynamic CT angiography within 9 hours after stroke-onset. We defined poor outcome as a modified Rankin Scale score of ≥3. Association between the extent and velocity of CVF and poor outcome at 3 months was analyzed with Poisson-regression. Prognostic value of optimal CVF (maximum opacification of cortical veins) in addition to age, stroke severity, treatment, Alberta Stroke Program Early CT score, cerebral blood flow, and collateral status was assessed with logistic regression and summarized with the area under the curve.

RESULTS

Eighty-eight patients were included, with a mean age of 67 years. By combining the extent and velocity of optimal CVF, we observed a decreased risk of poor outcome in patients with good and fast optimal CVF, risk ratio of 0.5 (95% confidence interval, 0.3-0.7). Extent and velocity of optimal CVF had additional prognostic value (area under the curve, 0.88; 95% confidence interval, 0.77-0.98; P<0.02) compared with a model without CVF information.

CONCLUSIONS

The combination of extent and velocity of optimal CVF, as assessed with dynamic CT angiography, is useful to identify patients with acute middle cerebral artery stroke at higher risk of poor clinical outcome at 3-month follow-up.

CLINICAL TRIAL REGISTRATION

URL: http://www.trialregister.nl/trialreg and http://www.clinicaltrials.gov. Unique identifier: NTR1804 and NCT00880113, respectively.

The evolving roles of pericyte in early brain injury after subarachnoid hemorrhage

Despite accumulated understanding on the mechanisms of early brain injury and improved management of subarachnoid hemorrhage (SAH), it is still one of the serious and refractory health problems around the world. Traditionally, pericyte, served as capillary contraction handler, is recently considered as the main participant of microcirculation regulation in SAH pathophysiology. However, accumulate evidences indicate that pericyte is much more than we already know. Therefore, we briefly review the characteristics, regulation pathways and functions of pericyte, aim to summarize the evolving new pathophysiological roles of pericyte that are implicated in early brain injury after SAH and to improve our understanding in order to explore potential novel therapeutic options for patients with SAH. This article is part of a Special Issue entitled SI: Cell Interactions In Stroke.