Regulation of cerebral vasculature in normal and ischemic brain.
Kulik Tobias,Kusano Yoshikazu,Aronhime Shimon,Sandler Adam L,Winn H Richard
We outline the mechanisms currently thought to be responsible for controlling cerebral blood flow (CBF) in the physiologic state and during ischemia, focusing on the arterial pial and penetrating microcirculation. Initially, we categorize the cerebral circulation and then review the vascular anatomy. We draw attention to a number of unique features of the cerebral vasculature, which are relevant to the microcirculatory response during ischemia: arterial histology, species differences, collateral flow, the venous drainage, the blood-brain barrier, astrocytes and vascular nerves. The physiology of the arterial microcirculation is then assessed. Lastly, we review the changes during ischemia which impact on the microcirculation. Further understanding of the normal cerebrovascular anatomy and physiology as well as the pathophysiology of ischemia will allow the rational development of a pharmacologic therapy for human stroke and brain injury.
The ICV sign as a marker of increased cerebral blood transit time.
Menon Bijoy K,Bai Helin Daniel,Modi Jayesh,Demchuk Andrew M,Hudon Mark,Goyal Mayank,Watson Timothy W J
The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques
OBJECTIVE/BACKGROUND:We describe the internal cerebral vein (ICV) sign, which is a hypo-opacification of the ICV on computed tomogram angiography (CTA) as a new marker of increased cerebral blood transit-time in ipsilateral internal carotid artery occlusions (ICAO). METHODS:A retrospective analysis of 153 patients with acute unilateral M1 middle cerebral artery (MCA) occlusions ± ICAOs was performed. The degree of contrast opacification of the ICV on the ipsilesional side was compared to that of the unaffected side. RESULTS:Of 153 patients in our study, 135 had M1 MCA occlusions ± intra-cranial ICAO (M1±iICAO) and 18 had isolated extracranial ICAO (eICAO). In the patients with proximal M1±iICAO, 57/65 (87.1%) showed the ICV sign. Of the 8 patients without the ICV sign in this group, 6 had prominent lenticulostriate arteries arising from the non-occluded M1 segment, 1 had a recurrent artery of Huebner, and 1 had filling of distal ICA/M1 segment through prominent Circle of Willis collaterals. For the 70 patients with isolated distal M1±iICAO, 7/70 (10%) showed the ICV sign, with all 7 showing occluded lenticulostriate arteries. Of the patients with eICAO, 8/18 showed the ICV sign, all 8 with the ICV sign had poor Circle of Willis collaterals. CONCLUSIONS:The ICV sign correlates well with presence of proximal M1±iICAO in patients with either occluded lenticulostriate arteries or poor Circle of Willis collaterals. In patients with eICAO, the sign correlates with reduced Circle of Willis collaterals and may be a marker of increased ipsilateral cerebral blood transit time.
Detection of important venous collaterals by computed tomography venogram in multisutural synostosis. Case report and review of the literature.
Al-Otibi Merdas,Jea Andrew,Kulkarni Abhaya V
Journal of neurosurgery
The authors describe the novel use of computed tomography (CT) venography in the preoperative evaluation of a child with Crouzon syndrome who was being considered for Chiari decompression. This 18-month-old girl presented with hydrocephalus (treated with a ventriculoperitoneal shunt) and persistent symptomatic Chiari malformation and associated syrinx. A CT venogram was obtained because of the well-described relationship between multisutural craniosynostosis and abnormal intracranial-to-extracranial venous drainage. The CT venogram showed widely dilated vertebral and paravertebral veins located in the paraspinous muscles of the craniocervical junction. Because of the risk of massive intraoperative blood loss and/or occlusion of important collateral draining veins leading to intracranial venous hypertension and intractably raised intracranial pressure, the planned posterior fossa decompression was not performed. Computed tomography venography is an easily obtained study that we recommend in the evaluation of children with multisutural craniosynostosis prior to cranial surgical interventions.
Preoperative evaluation of venous systems with computed tomography venography in parasagittal meningiomas.
Zhen Junping,Liu Cheng,Jiang Baodong,He Jingzhen,Pang Qi,Wang Guangbin
Journal of computer assisted tomography
OBJECTIVE:Parasagittal meningiomas (PSM) may pose a difficult surgical challenge because venous patency and collateral anastomoses have to be clearly defined for correct surgical planning. The aim of this study was to study the diagnostic accuracy of computed tomography venography (CTV) in assessing the superior sagittal sinus (SSS) obstruction and venous collaterals. METHODS:Twenty-four patients undergoing surgery for meningiomas located adjacent to the SSS were prospectively evaluated. All the patients underwent both conventional computed tomography examination and CTV. Computed tomography venography was evaluated by 2 expert neuroradiologists to assess (1) patency of the sinus (patent/occluded), (2) the extent of occlusion (in centimeters), and (3) the number of collateral anastomoses close to the insertion of the meningioma. Computed tomography venography assessment was compared with surgery. All patients were operated on, and intraoperative findings were taken as the criterion standard. RESULTS:Computed tomography venography showed the sinus to be occluded in 6 cases. Computed tomography venography data were confirmed by surgery, showing 6 patients to have have an occlusion of the SSS. The CTV sensitivity was thus 100%. Computed tomography venography depicted 83% of collateral venous anastomoses close to the meningioma as subsequently confirmed by surgery. CONCLUSIONS:In the preoperative planning for patients with meningiomas located close to the SSS, CTV can provide additional and more reliable information concerning venous infiltration and the presence of collateral anastomoses compared with noncontrast computed tomography.
Intracranial venous drainage through spinal veins.
Choudhary Arabinda Kumar,Dias Mark S,Iantosca Mark
Delaware medical journal
There is extensive collateral networking at the craniocervical junction with a substantial anatomical and functional continuity between the veins, venous sinuses, and venous plexuses of the brain and spine. The predominant pathway for intracranial blood outflow may depend on the level and degree of obstruction. We are presenting an unusual case of predominant egress of intracranial blood through enlarged spinal canal venous collaterals due to thrombosis of the intracranial venous sinuses. Awareness of this unique pattern of venous drainage of the cranium is important and should be considered in the differential diagnosis of spinal arteriovenous malformation (AVM) or arteriovenous fistula (AVF). Magnetic Resonance Venography (MRV) of the brain should be considered to exclude intracranial thrombosis in these cases.
Partial aortic occlusion and cerebral venous steal: venous effects of arterial manipulation in acute stroke.
Pranevicius Osvaldas,Pranevicius Mindaugas,Liebeskind David S
Acute ischemic stroke therapy emphasizes early arterial clot lysis or removal. Partial aortic occlusion has recently emerged as an alternative hemodynamic approach to augment cerebral perfusion in acute ischemic stroke. The exact mechanism of cerebral flow augmentation with partial aortic occlusion remains unclear and may involve more than simple diversion of arterial blood flow from the lower body to cerebral collateral circulation. The cerebral venous steal hypothesis suggests that even a small increase in tissue pressure in the ischemic area will divert blood flow to surrounding regions with lesser tissue pressures. This may cause no-reflow (absence of flow after restoration of arterial patency) in the ischemic core and "luxury perfusion" in the surrounding regions. Such maldistribution may be reversed with increased venous pressure titrated to avoid changes in intracranial pressure. We propose that partial aortic occlusion enhances perfusion in the brain by offsetting cerebral venous steal. Partial aortic occlusion redistributes blood volume into the upper part of the body, manifested by an increase in central venous pressure. Increased venous pressure recruits the collapsed vascular network and, by eliminating cerebral venous steal, corrects perifocal perfusion maldistribution analogous to positive end-expiratory pressure recruitment of collapsed airways to decrease ventilation/perfusion mismatch in the lungs.
Venous outflow of the brain after bilateral complete jugular ligation.
Ensari Serdar,Kaptanoğlu Erkan,Tun Kağan,Gün Taylan,Beşkonakli Etem,Celikkanat Serdar,Dere Hüseyin,Cekirge Saruhan
A case of a patient with bilateral internal, external, posterior external and anterior jugular vein ligations and excisions performed in the neck due to a larynx tumor is presented. Radical neck dissection is a standard otorhinolaryngological procedure in the management of head and neck cancer patients with bilateral lymph node metastasis to the neck. Sacrifice of both internal and external jugular veins bilaterally has been recognized as a dangerous approach leading to intracranial hypertension with subsequent neurological sequela and death. In this report, we aimed to demonstrate how venous outflow from the brain diverts after jugular venous system obliteration. After bilateral jugular vein ligations, digital subtraction angiography (DSA) showed that the venous drainage route of the brain had been diverted from the jugular veins to the vertebral venous plexus.
Venous imaging-based biomarkers in acute ischaemic stroke.
Munuera Josep,Blasco Gerard,Hernández-Pérez María,Daunis-I-Estadella Pepus,Dávalos Antoni,Liebeskind David S,Wintermark Max,Demchuk Andrew,Menon Bijoy K,Thomalla Götz,Nael Kambiz,Pedraza Salvador,Puig Josep
Journal of neurology, neurosurgery, and psychiatry
Vascular neuroimaging plays a decisive role in selecting the best therapy in patients with acute ischaemic stroke. However, compared with the arterial system, the role of veins has not been thoroughly studied. In this review, we present the major venous imaging-based biomarkers in ischaemic stroke. First, the presence of hypodense veins in the monophasic CT angiography ipsilateral to the arterial occlusion. Second, the asymmetry of venous drainage in the pathological cerebral hemisphere on CT and MRI dynamic angiography. Finally, the presence of hypodense veins on T2* -based MRI. From the physiological point of view, the venous imaging-based biomarkers would detect the alteration of brain perfusion (flow), as well as the optimisation of extraction oxygen mechanisms (misery perfusion). Several studies have correlated the venous imaging-based biomarkers with grade of collateral circulation, the ischaemic penumbra and clinical functional outcome. Although venous imaging-based biomarkers still have to be validated, growing evidence highlights a potential complementary role in the acute stroke clinical decision-making process.
Venous sacrifice in neurosurgery: new insights from venous indocyanine green videoangiography.
Ferroli Paolo,Acerbi Francesco,Tringali Giovanni,Albanese Erminia,Broggi Morgan,Franzini Angelo,Broggi Giovanni
Journal of neurosurgery
OBJECT:The purpose of this paper is to evaluate whether venous indocyanine green (ICG) videoangiography has any potential for predicting the presence of a safe collateral circulation for veins that are at risk for intentional or unintentional damage during surgery. METHODS:The authors performed venous ICG videoangiography during 153 consecutive neurosurgical procedures. On those occasions in which a venous sacrifice occurred during surgery, whether that sacrifice was preplanned (intended) or unintended, venous ICG videoangiography was repeated so as to allow us to study the effect of venous sacrifice. A specific test to predict the presence of venous collateral circulation was also applied in 8 of these cases. RESULTS:Venous ICG videoangiography allowed for an intraoperative real-time flow assessment of the exposed veins with excellent image quality and resolution in all cases. The veins observed in this study were found to be extremely different with respect to flow dynamics and could be divided in 3 groups: 1) arterialized veins; 2) fast-draining veins with uniform filling and clear flow direction; and 3) slow-draining veins with nonuniform filling. Temporary clipping was found to be a simple and reversible way to test for the presence of potential anastomotic circulation. CONCLUSIONS:Venous ICG videoangiography is able to reveal substantial variability in the venous flow dynamics. "Slow veins," when they are tributaries of bridging veins, might hide a potential for anastomotic circulation that deserve further investigation.
Magnetic resonance imaging quantification of compliance and collateral flow in late-onset idiopathic aqueductal stenosis: venous pathophysiology revisited.
Bateman Grant A
Journal of neurosurgery
OBJECT:Findings in animal models of noncommunicating hydrocephalus have suggested that a reduction in compliance of the superior sagittal sinus, an elevation in venous outflow pressure, and the development of venous collateral flow may be associated with this condition. Although elevated venous pressure is known to cause hydrocephalus in children, this mechanism has fallen out of favor as a theory in adults. METHODS:Twenty-one patients with late-onset idiopathic aqueductal stenosis (LIAS) underwent magnetic resonance imaging with flow quantification measuring the degree of ventricular enlargement, sulcal compression, total blood inflow, superior sagittal/straight sinus outflow, aqueduct flow, arteriovenous delay (AVD), and the extent of collateral venous flow. Data obtained in these patients were compared with those obtained in 21 age-matched control individuals. RESULTS:There was a reduction in compliance in the patients with LIAS in whom the AVD decreased by 50% (p = 0.01). The arterial inflow and the straight sinus outflow were normal, but the sagittal sinus outflow was reduced by 23% (p = 0.001). This indicated that significant collateral venous outflow pathways were draining blood away from the superficial but not the deep drainage system. CONCLUSIONS:Similar to the animal models, patients with LIAS exhibit a reduced venous compliance and an elevation in venous collateral flow. Together, these findings suggest that an elevation in venous pressure may be associated with this disease process. A review of the literature has indicated that only subtle differences may exist in the pathophysiology among patients with LIAS, normal-pressure hydrocephalus, and idiopathic intracranial hypertension.
A Combined Arterial and Venous Grading Scale to Predict Outcome in Anterior Circulation Ischemic Stroke.
Parthasarathy Rajsrinivas,Sohn Sung-Il,Jeerakathil Thomas,Kate Mahesh P,Mishra Sachin M,Nambiar Vivek K,Ahmad Aftab,Menon Bijoy K,Shuaib Ashfaq
Journal of neuroimaging : official journal of the American Society of Neuroimaging
OBJECTIVE:Prognostic evaluation based on cortical vein score difference in stroke (PRECISE) score, a novel venous grading scale better predicted stroke outcomes. Henceforth, we aimed to describe and determine if a physiologically relevant combined arterial and venous grading scale (CRISP grading scale) is accurate in determining 90-day stroke outcomes in patients with proximal arterial occlusion in the anterior circulation. METHODS:Data are from the Keimyung Stroke Registry. Consecutive patients with M1 middle cerebral artery (MCA) or terminal internal carotid artery (ICA) occlusion on CT-angiography (CTA) from May-2004 to July-2008 were included. The affected hemisphere 'four veins composite score' and 'arterial collaterals' were each graded 'good' and 'poor'. On the combined scale, a 'good' grade represented a 'good' score on both scales and a 'poor' grade represented a 'poor' score on both scales. The 'other two' combinations were graded 'intermediate.' RESULTS:Eighty-one patients were included in the study. Dummy variable regression analysis demonstrated that poor outcome was commonly seen in the group with poor arterial and venous grades [OR(95%CI); 48 (8.24, 279.598); P < 0.00001] as opposed to poor arterial collaterals alone [OR(95%CI); 9.6(1.483,62.162); P = 0.018]. In multivariate analysis the CRISP grade [OR(95%CI); 2.638(1.192, 6.039), P = 0.017] and National Institutes of Health Stroke Scale [OR(95%CI);1.230(1.085, 1.395),P = 0.001(per unit increase)] emerged as the independent predictors of poor outcome (modified Rankin Scale >2) when adjusted for other imaging predictors of outcome. CONCLUSION:CRISP grading was precise in predicting stroke outcomes when compared to individual imaging scales including arterial collateral grading, PRECISE score and CTA-SI ASPECTS in patients with proximal arterial occlusion in the anterior circulation.
A new hemodynamic model for the study of cerebral venous outflow.
Gadda G,Taibi A,Sisini F,Gambaccini M,Zamboni P,Ursino M
American journal of physiology. Heart and circulatory physiology
We developed a mathematical model of the cerebral venous outflow for the simulation of the average blood flows and pressures in the main drainage vessels of the brain. The main features of the model are that it includes a validated model for the simulation of the intracranial circulation and it accounts for the dependence of the hydraulic properties of the jugular veins with respect to the gravity field, which makes it an useful tool for the study of the correlations between extracranial blood redistributions and changes in the intracranial environment. The model is able to simulate the average pressures and flows in different points of the jugular ducts, taking into account the amount of blood coming from the anastomotic connections; simulate how the blood redistribution due to change of posture affects flows and pressures in specific points of the system; and simulate redistributions due to stenotic patterns. Sensitivity analysis to check the robustness of the model was performed. The model reproduces average physiologic behavior of the jugular, vertebral, and cerebral ducts in terms of pressures and flows. In fact, jugular flow drops from ∼11.7 to ∼1.4 ml/s in the passage from supine to standing. At the same time, vertebral flow increases from 0.8 to 3.4 ml/s, while cerebral blood flow, venous sinuses pressure, and intracranial pressure are constant around the average value of 12.5 ml/s, 6 mmHg, and 10 mmHg, respectively. All these values are in agreement with literature data.
The preservation and reconstruction of cerebral veins and sinuses.
Sekhar Laligam N,Chanda Amitabha,Morita Akio
Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia
Although cerebral veins and venous sinuses are very important to the neurosurgeon, they have received adequate attention only recently. The consequences of cerebral venous occlusion are well known. When the venous outflow is compromised due to a lack of adequate collateral circulation, venous infarction follows, with swelling, haemorrhage and neuronal death. The clinical consequences will depend upon the region of involvement of the brain and the site of the infarcted tissue. The symptoms may include seizures, hemiplegia, aphasia, coma and death. Similarly, the consequences of cerebral venous sinus occlusion depend upon the availability of collateral circulation. When such collaterals are not available, papilledema and visual loss and a pseudotumour cerebri syndrome are observed in milder cases, whereas, severe diffuse brain swelling, coma and death may be observed in severe cases. Acute venous or venous sinus occlusion is potentially very dangerous, whereas slow and chronic venous or venous sinus occlusion is better tolerated. Even in such patients, some neurological manifestations may follow, when the collaterals are poor.
[Collateral venous channels in occlusion of deep cerebral veins and sinuses].
Asari S,Yabuno N,Ohmoto T
No to shinkei = Brain and nerve
The authors report on the relationship between occlusion or stenosis of the deep cerebral veins and sinuses and the development of collateral venous channels in pineal region tumors. Five cases of meningioma arising from the falcotentorial junction were the subject of this study. There were two males and three females with an average age of 51.2 years (range: 26-67). The straight sinus (SS) and posterior part of the great vein of Galen (GVG) were included in the occlusion or stenosis of the deep cerebral veins and sinuses in 3 cases, the GVG, SS and posterior part of the internal cerebral vein in 1, and the SS alone in 1. The various types of collateral venous channels following the occlusion could be classified a type 1, from the basal vein of Rosenthal (BVR) to the petrosal vein via the lateral mesencephalic and/or anterior pontomesencephalic veins; type 2, via the veins on the medial surface of the parietal and/or occipital lobe to the superior sagittal sinus (SSS); type 3, dilated superficial anastomotic veins; type 4, via the posterior fossa venous circulation to the transverse sinus or the SS; and type 5, via the falcian veins to the SSS. The first three types of collateral venous channels seem to be important following occlusion or stenosis of deep cerebral veins and sinuses. Stereoscopic angiograms are essential to analyze deep venous channels around deep-seated tumors. Clear identification of occlusion or stenosis and the development of venous system collaterals on angiograms is important to the surgical treatment of pineal region tumors.
Usefulness of 4D-CTA in the detection of cerebral dural sinus occlusion or stenosis with collateral pathways.
Ono Y,Abe K,Suzuki K,Iimura H,Sakai S,Uchiyama S,Okada Y
The neuroradiology journal
In time-resolved CT angiography (4D-CTA), it is of substantial merit to detect the veins and sinuses of the whole brain with the simultaneous demonstration of the natural drainage flow in order to find occlusion or stenosis of the dural sinuses with collateral pathways. As preoperative information for patients with brain tumors, it is important to detect feeding arteries, incidentally found aneurysms or other vascular lesions, and to detect patency of the dural sinuses and the important cortical veins, whether they are compressed by tumors or not. On the other hand, cerebral venous thrombosis (CVT) may occur in patients due to various causes, which has not been unusual in recent years. For patients with acute symptomatic or chronic non-symptomatic CVT, identification of dural sinus occlusion (DSO) or dural sinus stenosis (DSS) and compensatory collateral pathways is necessary for suitable thrombolytic therapy or careful investigation to avoid further CVT. This study reviews our experiences in 116 cases of 4D-CTA for 90 patients with brain tumors and 26 other patients including 11 with arteriovenous malformation, and four with acute CVT and other conditions. 4D-CTA presented DSO/DSS with compensatory venous collateral pathways, which was helpful to detect the severity of the venous abnormality, and see whether it was compressed by brain tumors, or due to other causes in patients with symptomatic or non-symptomatic CVT. 4D-CTA is a useful non-invasive diagnostic tool to detect cerebral venous abnormalities as an alternative to DSA.
Intracranial venous collaterals in cerebral venous thrombosis: clinical and imaging impact.
Barboza Miguel A,Mejías Carolina,Colin-Luna Jonathan,Quiroz-Compean Alejandro,Arauz Antonio
Journal of neurology, neurosurgery, and psychiatry
BACKGROUND AND PURPOSE:Few studies have examined collateral formation in patients with cerebral venous thrombosis (CVT). The aim of this study was to analyse the impact of baseline intracranial venous collaterals on the clinical outcome and imaging features of patients with acute CVT. MATERIAL AND METHODS:MRIs from consecutive patients with acute CVT were retrospectively analysed. The category system described by Qureshi was used to assess the pattern of venous collaterals. Clinical and imaging features and outcomes were analysed using bivariate and multivariate models to assess the association of collateral patterns with the type of parenchymal lesions and clinical outcome (modified Rankin Scale) at 30 and 90 days. RESULTS:One hundred patients were included (77 women; median age 32 years; and median of 18 months of follow-up). Venous collaterals were present in 88% of the patients; type I collaterals in 3 patients, type II collaterals in 27 patients, and type III collaterals in 58 patients. Twelve patients did not exhibit any collaterals. Cohen's κ coefficient between evaluators was 0.86. In the bivariate analysis, type III collaterals were associated with isolated intracranial hypertension and complete recovery, whereas type I collaterals were associated with encephalopathy. However, in the multivariate regression analysis, the collateral pattern was not associated with clinical presentation, type of brain lesion or outcome. CONCLUSIONS:Intracranial venous collaterals are frequently found in patients with CVT during the acute phase. However, they do not have an independent effect on the type of brain damage, clinical manifestations or prognosis.
Leptomeningeal collateralization in acute ischemic stroke: impact on prominent cortical veins in susceptibility-weighted imaging.
Verma Rajeev K,Hsieh Kety,Gratz Pascal P,Schankath Adrian C,Mordasini Pasquale,Zubler Christoph,Kellner-Weldon Frauke,Jung Simon,Schroth Gerhard,Gralla Jan,El-Koussy Marwan
European journal of radiology
BACKGROUND:The extent of hypoperfusion is an important prognostic factor in acute ischemic stroke. Previous studies have postulated that the extent of prominent cortical veins (PCV) on susceptibility-weighted imaging (SWI) reflects the extent of hypoperfusion. Our aim was to investigate, whether there is an association between PCV and the grade of leptomeningeal arterial collateralization in acute ischemic stroke. In addition, we analyzed the correlation between SWI and perfusion-MRI findings. METHODS:33 patients with acute ischemic stroke due to a thromboembolic M1-segment occlusion underwent MRI followed by digital subtraction angiography (DSA) and were subdivided into two groups with very good to good and moderate to no leptomeningeal collaterals according to the DSA. The extent of PCV on SWI, diffusion restriction (DR) on diffusion-weighted imaging (DWI) and prolonged mean transit time (MTT) on perfusion-imaging were graded according to the Alberta Stroke Program Early CT Score (ASPECTS). The National Institutes of Health Stroke Scale (NIHSS) scores at admission and the time between symptom onset and MRI were documented. RESULTS:20 patients showed very good to good and 13 patients poor to no collateralization. PCV-ASPECTS was significantly higher for cases with good leptomeningeal collaterals versus those with poor leptomeningeal collaterals (mean 4.1 versus 2.69; p=0.039). MTT-ASPECTS was significantly lower than PCV-ASPECTS in all 33 patients (mean 1.0 versus 3.5; p<0.00). CONCLUSIONS:In our small study the grade of leptomeningeal collateralization correlates with the extent of PCV in SWI in acute ischemic stroke, due to the deoxyhemoglobin to oxyhemoglobin ratio. Consequently, extensive PCV correlate with poor leptomeningeal collateralization while less pronounced PCV correlate with good leptomeningeal collateralization. Further SWI is a very helpful tool in detecting tissue at risk but cannot replace PWI since MTT detects significantly more ill-perfused areas than SWI, especially in good collateralized subjects.
A novel method to assess pial collateralization from stroke perfusion MRI: subdividing T into anatomical compartments.
Potreck Arne,Seker Fatih,Hoffmann Angelika,Pfaff Johannes,Nagel Simon,Bendszus Martin,Heiland Sabine,Pham Mirko
OBJECTIVES:To develop and validate a quantitative and observer-independent method to evaluate pial collateral circulation by DSC-perfusion MRI and test whether this novel method delivers diagnostic information which is redundant to or independent from conventional penumbra imaging by the mismatch approach. METHODS:We retrospectively identified 47 patients with M1 occlusion who underwent MR diffusion/perfusion imaging and mechanical thrombectomy at our facility. By automated registration and segmentation, T delays were attributed specifically to the pial, cortical and parenchymal compartments. The resulting pial volumes at delay were defined as the pial T map-assessed collateral score (TMACS) and correlated with gold standard digital subtraction angiography (DSA). Mismatch ratio was assessed by conventional penumbra defining MRI criteria. RESULTS:Strong correlation was found between TMACS and angiographically assessed collateral score (Pearson ρ = -0.74, p < 0.001). In multiple logistic regression, both good collaterals according to TMACS [OR 4.3 (1.1-19, p = 0.04)] and mismatch ratio ≥ 3.5 [OR 12.3 (1.88-249, p = 0.03)] were independent predictors of favourable clinical outcome. CONCLUSIONS:Perfusion delay in the pial compartment, as evaluated by TMACS, closely reflects the extent of pial collaterals in gold-standard DSA. TMACS and mismatch ratio were found to be complementary predictors of a favourable clinical outcome, each adding independent predictive information. KEY POINTS:• MRI-DSC perfusion delay specific in the pial compartment reflects leptomeningeal collateralization. • A novel quantitative- and observer-independent marker of collateral status (TMACS) is introduced. • Quantification of collateral status leads to an independent predictor of neurological outcome.
Cerebral venous collaterals: A new fort for fighting ischemic stroke?
Tong Lu-Sha,Guo Zhen-Ni,Ou Yi-Bo,Yu Yan-Nan,Zhang Xiao-Cheng,Tang Jiping,Zhang John H,Lou Min
Progress in neurobiology
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.
Asymmetric Deep Medullary Veins in Patients With Occlusion of a Large Cerebral Artery: Association With Cortical Veins, Leptomeningeal Collaterals, and Prognosis.
Xu Zhihua,Duan Yang,Yang Benqiang,Huang Xin,Pei Yusong,Li Xiaoqiu
Frontiers in neurology
To explore the relationships of asymmetric deep medullary veins (ADMV) to asymmetric cortical veins (ACV), leptomeningeal collaterals and prognosis in patients with occlusion of a large cerebral artery. Clinical and imaging data of 56 patients with occlusion of a large cerebral artery were collected and reviewed. We assessed the time delayed between stroke onset and MR imaging (within 24 h of stroke onset), extension of cerebral infarction using the Alberta stroke program early CT score based on diffusion-weighted imaging (ASPECTs). ADMV and ACV were assessed using susceptibility-weighted imaging. The presence of ADMV (ACV) was defined as deep medullary veins (cortical veins) of the affected hemisphere that were greater in number and diameter than in the contralateral hemisphere. To evaluate leptomeningeal collaterals, the hyperintense vessel sign (HVS) was detected using T2 weighted fluid attenuated inversion recovery images. At 90 days, a modified Rankin scale score (mRS) was assessed to evaluate the clinical outcome. Of 56 patients, 27 presented with ADMV. Those patients who presented with and without ADMV differed significantly in HVS and ACV ( < 0.05) but not in time delayed between stroke onset and MR imaging, age, gender, stroke risk factors, baseline NIHSS score, or modified Rankin scale score at 3 months ( > 0.05). Logistic regression analysis found that the presence of ADMV was independently related to HVS and ACV (ACV: OR 95% C.I., 1.287-4.368; HVS: OR 95% C.I., 1.132-4.887). The presence of ADMV on SWI was associated with prominent ACV and good leptomeningeal collateral flow but was not related to prognosis in patients with occlusion of a large cerebral artery.
Prevention of the collapse of pial collaterals by remote ischemic perconditioning during acute ischemic stroke.
Ma Junqiang,Ma Yonglie,Dong Bin,Bandet Mischa V,Shuaib Ashfaq,Winship Ian R
Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism
Collateral circulation is a key variable determining prognosis and response to recanalization therapy during acute ischemic stroke. Remote ischemic perconditioning (RIPerC) involves inducing peripheral ischemia (typically in the limbs) during stroke and may reduce perfusion deficits and brain damage due to cerebral ischemia. In this study, we directly investigated pial collateral flow augmentation due to RIPerC during distal middle cerebral artery occlusion (MCAo) in rats. Blood flow through pial collaterals between the anterior cerebral artery (ACA) and the MCA was assessed in male Sprague Dawley rats using in vivo laser speckle contrast imaging (LSCI) and two photon laser scanning microscopy (TPLSM) during distal MCAo. LSCI and TPLSM revealed that RIPerC augmented collateral flow into distal MCA segments. Notably, while control rats exhibited an initial dilation followed by a progressive narrowing of pial arterioles 60 to 150-min post-MCAo (constricting to 80-90% of post-MCAo peak diameter), this constriction was prevented or reversed by RIPerC (such that vessel diameters increased to 105-110% of post-MCAo, pre-RIPerC diameter). RIPerC significantly reduced early ischemic damage measured 6 h after stroke onset. Thus, prevention of collateral collapse via RIPerC is neuroprotective and may facilitate other protective or recanalization therapies by improving blood flow in penumbral tissue.
Transition to collateral flow after arterial occlusion predisposes to cerebral venous steal.
Pranevicius Osvaldas,Pranevicius Mindaugas,Pranevicius Henrikas,Liebeskind David S
BACKGROUND AND PURPOSE:Stroke-related tissue pressure increase in the core and penumbra determines regional cerebral perfusion pressure (rCPP) defined as a difference between local inflow pressure and venous or tissue pressure, whichever is higher. We previously showed that venous pressure reduction below the pressure in the core causes blood flow diversion-cerebral venous steal. Now we investigated how transition to collateral circulation after complete arterial occlusion affects rCPP distribution. METHODS:We modified parallel Starling resistor model to simulate transition to collateral inflow after complete main stem occlusion. We decreased venous pressure from the arterial pressure to zero and investigated how arterial and venous pressure elevation augments rCPP. RESULTS:When core pressure exceeded venous, rCPP=inflow pressure in the core. Venous pressure decrease from arterial pressure to pressure in the core caused smaller inflow pressure to drop augmenting rCPP. Further drop of venous pressure decreased rCPP in the core but augmented rCPP in penumbra. After transition to collateral circulation, lowering venous pressure below pressure in the penumbra further decreased rCPP and collaterals themselves became a pathway for steal. Venous pressure level at which rCPP in the core becomes zero we termed the "point of no reflow." Transition from direct to collateral circulation resulted in decreased inflow pressure, decreased rCPP, and a shift of point of no reflow to higher venous loading values. Arterial pressure augmentation increased rCPP, but only after venous pressure exceeded point of no reflow. CONCLUSIONS:In the presence of tissue pressure gradients, transition to collateral flow predisposes to venous steal (collateral failure), which may be reversed by venous pressure augmentation.
An ultrasound model to calculate the brain blood outflow through collateral vessels: a pilot study.
Zamboni Paolo,Sisini Francesco,Menegatti Erica,Taibi Angelo,Malagoni Anna Maria,Morovic Sandra,Gambaccini Mauro
BACKGROUND:The quantification of the flow returning from the head through the cervical veins and the collaterals of the internal jugular vein (IJV), is becoming of prominent interest in clinical practice. We developed a novel model to calculate the cerebral venous return, normalized to the arterial inflow, in the different segments of the IJV. METHODS:We assessed, by established Echo Colour Doppler (ECD) methodology, the head inflow (HBinF) defined as the sum of common carotids and vertebral arteries, as well as the cerebral flow (CBF) defined as the sum of internal carotid and vertebral arteries. We also assessed the head outflow (HBoutF) defined as the sum of the measurements at the junction of the IJV and the vertebral veins. In addition, we also calculated the collateral flow index (CFI) by estimating the flow which re-enters directly into the superior vena cava as the amount of blood extrapolated by the difference between the HBinF and the HBoutF. We preliminarily tested the model by comparing ten healthy controls (HC) with ten patients affected by chronic cerebral spinal venous insufficiency (CCSVI), a condition characterized by some blockages in the IJV which are bypassed by collateral circulation. RESULTS:In HC the HBinF was 956+-105ml/min, whereas the HBoutF was > 90% of the HBinF, leading to a final CFI value of 1%. The last result shows that a very small amount of blood is drained by the collaterals. In upright we confirmed a reduction of the outflow through the IJV which increased CFI to 9%. When we applied the model to CCSVI, the HBinF was not significantly different from controls. In supine, the flow of CCSVI patients in the IJV junction was significantly lower (p < 0.001) while the correspondent CFI value significantly increased (61%, p < 0.0002). CONCLUSIONS:Our preliminary application of the novel model in the clinical setting suggests the pivotal role of the collateral network in draining the blood into the superior vena cava under CCSVI condition.
Falcine Sinus and Parafalcine Collateral Veins in Meningiomas Invading the Superior Sagittal Sinus.
Yin Tengkun,Zhang Hao,Wang Wei,Zhang Liyong,Wang Shousen
BACKGROUND:Venous collaterals form because of occlusion of the superior sagittal sinus (SSS), thus preserving venous drainage. Previous studies have focused on the evaluation and protection of sinuses and cortical veins and have neglected the collaterals between the SSS and deep venous system, which are important for surgical planning. We aimed to study the venous compensatory patterns inside and on both sides of the cerebral falx (parafalx) in patients with meningioma invading the SSS. METHODS:Conventional magnetic resonance imaging, magnetic resonance venography, and a three-dimensional reconstructed venous model of 45 patients were analyzed. The venous collateral pattern of the parafalx was divided into 4 types: A), with cerebral medial cortical vein displacement or hyperplasia; B), collaterals connect the 2 ends of the occluded segment of the SSS; C), collaterals connect the occluded segment of the SSS with the deep cerebral venous system; and D), recanalization or secondary formation of a falcine sinus. The incidence of each type in different occlusion grades and positions of the SSS was analyzed. RESULTS:The 4 types of venous collaterals were ranked according to their prevalence: A, 46.7%; C, 15.6%; D, 8.9%; and B, 4.4%. The collaterals of types B, C, and D were found only in patients with severe SSS occlusion, and both types C and D were found only in middle and posterior occlusions of the SSS. CONCLUSIONS:In meningiomas invading the SSS, especially with complete posterior SSS occlusion, the parafalcine collateral veins and falcine sinus should be evaluated preoperatively to avoid iatrogenic injury.
Venous collateral circulation of the extracranial cerebrospinal outflow routes.
Zamboni Paolo,Consorti Giuseppe,Galeotti Roberto,Gianesini Sergio,Menegatti Erica,Tacconi Giovanna,Carinci Francesco
Current neurovascular research
A new nosologic vascular pattern that is defined by chronic cerebrospinal venous insufficiency (CCSVI) has been strongly associated with multiple sclerosis. The picture is characterized by significant obstacles of the main extracranial cerebrospinal veins, the jugular and the azygous system, and by the opening of substitute circles. The significance of collateral circle is still neglected. To the contrary, substitute circles are alternative pathways or vicarious venous shunts, which permit the drainage and prevent intracranial hypertension. In accordance with the pattern of obstruction, even the intracranial and the intrarachidian veins can also become substitute circles; they permit redirection of the deviated flow, piping the blood toward available venous segments outside the central nervous system. We review the complex gross and radiological anatomy of collateral circulation found activated by the means of EchoColor-Doppler and selective venography in the event of CCSVI, focusing particularly on the suboccipital cavernous sinus (SCS), the condylar venous system, the pterygoid plexus, the thyroid veins, and the emiazygous-lumbar venous anastomosis with the left renal vein.
Use of ICG videoangiography and FLOW 800 analysis to identify the patient-specific venous circulation and predict the effect of venous sacrifice: a retrospective study of 172 patients.
Acerbi Francesco,Vetrano Ignazio G,Sattin Tommaso,Falco Jacopo,de Laurentis Camilla,Zattra Costanza M,Bosio Lorenzo,Rossini Zefferino,Broggi Morgan,Schiariti Marco,Ferroli Paolo
OBJECTIVE The best management of veins encountered during the neurosurgical approach is still a matter of debate. Even if venous sacrifice were to lead to devastating consequences, under certain circumstances, it might prove to be desirable, enlarging the surgical field or increasing the extent of resection in tumor surgery. In this study, the authors present a large series of patients with vascular or oncological entities, in which they used indocyanine green videoangiography (ICG-VA) with FLOW 800 analysis to study the patient-specific venous flow characteristics and the management workflow in cases in which a venous sacrifice was necessary. METHODS Between May 2011 and December 2017, 1972 patients were admitted to the authors' division for tumor and/or neurovascular surgery. They retrospectively reviewed all cases in which ICG-VA and FLOW 800 were used intraoperatively with a specific target in the venous angiographic phase or for the management of venous sacrifice, and whose surgical videos and FLOW 800 analysis were available. RESULTS A total of 296 ICG-VA and FLOW 800 studies were performed intraoperatively. In all cases, the venous structures were clearly identifiable and were described according to the flow direction and speed. The authors therefore defined different patterns of presentation: arterialized veins, thrombosed veins, fast-draining veins with anterograde flow, slow-draining veins with anterograde flow, and slow-draining veins with retrograde flow. In 16 cases we also performed a temporary clipping test to predict the effect of the venous sacrifice by the identification of potential collateral circulation. CONCLUSIONS ICG-VA and FLOW 800 analysis can provide complete and real-time intraoperative information regarding patient-specific venous drainage pattern and can guide the decision-making process regarding venous sacrifice, with a possible impact on reduction of surgical complications.
Prognostic evaluation based on cortical vein score difference in stroke.
Parthasarathy Rajsrinivas,Kate Mahesh,Rempel Jeremy L,Liebeskind David S,Jeerakathil Thomas,Butcher Kenneth S,Shuaib Ashfaq
BACKGROUND AND PURPOSE:Multimodal imaging in acute ischemic stroke defines the extent of arterial collaterals, resultant penumbra, and associated infarct core, yet limitations abound. We identified superficial and deep venous drainage patterns that predict outcomes in patients with a proximal arterial occlusion of the anterior circulation. METHODS:An observational study that used computed tomography (CT) angiography to detail venous drainage in a consecutive series of patients with a proximal anterior circulation arterial occlusion. The principal veins that drain the cortex (superficial middle cerebral, vein of Trolard, vein of Labbé, and basal vein of Rosenthal) and deep structures were scored with a categorical scale on the basis of degree of contrast enhancement. The Prognostic Evaluation based on Cortical vein score difference In Stroke score encompassing the interhemispheric difference of the composite scores of the veins draining the cortices (superficial middle cerebral+vein of Trolard+vein of Labbé+basal vein of Rosenthal) was analyzed with respect to 90-day modified Rankin Scale outcomes. RESULTS:Thirty-nine patients were included in the study. A Prognostic Evaluation based on Cortical vein score difference In Stroke score of 4 to 8 accurately predicted poor outcomes (modified Rankin Scale, 3-6; odds ratio, 20.53; P<0.001). On stepwise logistic regression analyses adjusted for CT Alberta stroke program early CT score, CT angiography collateral grading and National Institutes of Health Stroke Scale score, a Prognostic Evaluation based on Cortical vein score difference In Stroke score of 4 to 8 (odds ratio, 23.598; P=0.009) and an elevated admission National Institutes of Health Stroke Scale (odds ratio, 1.423; P=0.023) were independent predictors of poor outcome. CONCLUSIONS:The Prognostic Evaluation based on Cortical vein score difference In Stroke score, a novel measure of venous enhancement on CT angiography, accurately predicts clinical outcomes. Venous features on computed tomography angiography provide additional characterization of collateral perfusion and prognostication in acute ischemic stroke.
The safety of the intraoperative sacrifice of the deep cerebral veins.
Davidson Laurence,McComb J Gordon
Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery
BACKGROUND:The effect of surgically ligating the deep cerebral veins is often thought to be of significant risk. That concern and the paucity of information on surgery of the deep venous system confound surgical decision making when operations involve manipulation of the deep cerebral veins. DISCUSSION:The authors review the human and animal literature on the selective sacrifice of the deep cerebral veins. Robust experimental studies and limited clinical experience indicate that occlusion of one or several deep cerebral veins is generally safe.
Indocyanine green (ICG) temporary clipping test to assess collateral circulation before venous sacrifice.
Ferroli Paolo,Nakaji Peter,Acerbi Francesco,Albanese Erminia,Broggi Giovanni
BACKGROUND:As a general principle, sacrifice of cerebral veins at surgery is avoided. However, at times sacrifice of a vein may be desirable to increase surgical exposure. At present, no method exists to predict whether such sacrifice will be accommodated by the presence of collateral venous drainage. We show a simple technique to examine cerebral venous blood flow using indocyanine green videoangiography. METHODS:In two patients, parasagittal meningiomas were found to be associated with paramedian veins that impeded complete removal of the tumors. The suitability of veins removal was assessed by applying a temporary aneurysm clip and performing an indocyanine green videoangiogram. RESULTS:In one patient, stasis was observed in the vein. In the second patient, a collateral flow allowed the venous blood to drain. The former test was considered a counterindication for venous sacrifice, whereas the latter supported its feasibility. The vein was preserved in the former case and coagulated in the latter. In both cases, the patients did well. CONCLUSIONS:Although our limited study cannot prove that venous congestion or infarction can be avoided with this technique, it does provide direct evidence of the presence or absence of collaterals that can help guide intraoperative surgical decision-making.
Prolonged cerebral circulation time is more associated with symptomatic carotid stenosis than stenosis degree or collateral circulation.
Hu Yong-Sin,Guo Wan-Yuo,Lee I-Hui,Chang Feng-Chi,Lin Chung-Jung,Lin Chun-Jen,Luo Chao-Bao,Wu Chih-Chun,Lee Han-Jui
Journal of neurointerventional surgery
BACKGROUND AND PURPOSE:Current practice of revascularization for carotid stenosis (CS) primarily relies on symptoms and degree of stenosis. Other parameters, such as collateral circulation and cerebral circulation time (CCT), might influence the stroke risk in CS. This study was conducted to (1) investigate whether CCT is more associated with symptomatic CS than degree of stenosis and (2) elucidate the associations among the degree of stenosis, collateral status, and CCT. METHODS:From 2010 to 2016, 82 patients with unilateral CS were enrolled for DSA and divided into symptomatic and asymptomatic groups based on clinical presentation. CCT was defined as the difference between the time taken by the cavernous internal carotid artery and parietal vein to reach the maximal contrast medium intensities on lateral DSA. The degree of stenosis, collateral status, and CCT of the two groups were compared. Logistic regression analysis was performed to estimate the OR for symptomatic CS with the imaging variables. RESULTS:The symptomatic group had a significantly higher degree of stenosis and longer CCT. CCT (OR 1.95, p=0.013) was more associated with symptomatic CS than the degree of stenosis (OR 1.03, p0.229), after adjustment for potential confounders-namely, age, sex, antithrombotic use, and collateral status. Symptomatic high grade CS with collaterals had a non-significantly shorter CCT than those without collaterals. CONCLUSIONS:DSA derived CCT is more reflective of the hemodynamic differences between symptomatic and asymptomatic CS than degree of stenosis. Collaterals may not effectively reduce CCT in symptomatic high grade CS.
Cortical Vein Opacification for Risk Stratification in Anterior Circulation Endovascular Thrombectomy.
Hoffman Haydn,Ziechmann Robert,Swarnkar Amar,Masoud Hesham E,Gould Grahame
Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association
INTRODUCTION:There is continued interest in identifying factors that predict a favorable outcome after endovascular thrombectomy (EVT) for anterior circulation large vessel occlusion (ACLVO). We compared the predictive values of 2 different scoring systems for evaluating venous collateral circulation. METHODS:A retrospective review of patients who underwent EVT for ACLVO at a single institution was performed. Those who underwent preprocedural computed tomography angiography (CTA) were selected. The Cortical Vein Opacification Score (COVES) and Prognostic Evaluation based on Cortical vein score difference In Stroke (PRECISE) score were calculated from each patient's CTA. Our primary outcome of interest was the Modified Rankin Scale (mRS) score at 90 days. RESULTS:A total of 103 patients were included in the study (average age = 68.3 years, median National Institutes of Health Stroke Scale = 15). The mean time to reperfusion was 6.4 hours and Thrombolysis in Cerebral Infarction 2B or 3 reperfusion was achieved in 77.7% of cases. An unfavorable COVES score was significantly associated with an unfavorable (mRS 3-6) outcome (adjusted odds ratio [aOR]: 3.06; 95% confidence interval [CI] 1.15-8.13, P = .025), while an unfavorable PRECISE score was not (aOR: 1.02; 95% CI .37-2.80, P = .966). Based on the Receiver Operating Characteristic analysis, the COVES score had a sensitivity of 68.1%, specificity of 71.4%, and area under the curve (AUC) of .77. The PRECISE score had a sensitivity of 68.9%, specificity of 70.7%, and the AUC of .73. CONCLUSIONS:The COVES score, but not the PRECISE score, is associated with functional outcomes at 90 days after EVT for ACLVO.