Arteriovenous malformations and other vascular malformation syndromes

ZFYVE21 promotes endothelial nitric oxide signaling and vascular barrier function in the kidney during aging

ZFYVE21 is an ancient, endosome-associated protein that is highly expressed in endothelial cells (ECs) but whose function(s) in vivo are undefined. Here, we identified ZFYVE21 as an essential regulator of vascular barrier function in the aging kidney. ZFYVE21 levels significantly decline in ECs in aged human and mouse kidneys. To investigate attendant effects, we generated EC-specific Zfyve21-/- reporter mice. These knockout mice developed accelerated aging phenotypes including reduced endothelial nitric oxide (ENOS) activity, failure to thrive, and kidney insufficiency. Kidneys from Zfyve21 EC-/- mice showed interstitial edema and glomerular EC injury. ZFYVE21-mediated phenotypes were not programmed developmentally as loss of ZFYVE21 in ECs during adulthood phenocopied its loss prenatally, and a nitric oxide donor normalized kidney function in adult hosts. Using live cell imaging and human kidney organ cultures, we found that in a GTPase Rab5- and protein kinase Akt-dependent manner, ZFYVE21 reduced vesicular levels of inhibitory caveolin-1 and promoted transfer of Golgi-derived ENOS to a perinuclear Rab5+ vesicular population to functionally sustain ENOS activity. Thus, our work defines a ZFYVE21- mediated trafficking mechanism sustaining ENOS activity and demonstrates the relevance of this pathway for maintaining kidney function with aging.

Partial Endovascular Embolization of a Cerebral Arteriovenous Malformation in a Patient With Seizures Caused by a Steal Phenomenon: A Case Analysis

Cerebral arteriovenous malformations (cAVMs) are developmental pathologic lesions of the blood vessels of the brain in which multiple arteries shunt blood directly into the venous drainage network. They are lesions with an unclear etiology and, if left untreated, can bear significant risks of complications such as migraines, seizures, neurological deficits, and intracranial hemorrhages. The diagnosis is based on several imaging methods, with angiography being the primary method. Treatment modalities include microsurgery, radiosurgery, embolization with the intent of obliteration, and various multidisciplinary approaches. We aim to introduce the case of an adult female patient with symptomatic cAVM who underwent partial endovascular embolization of the lesion and evaluate her recovery and the overall reliability of her treatment modality. A 22-year-old female patient has presented to the Neurosurgery Clinic with clinical manifestations with photosensitive seizures, migraines, and a history of sleep disturbances persisting for a period of one year. An appointed MRI and angiography revealed the presence of a glomerular cAVM of the anterior parietal branch of the middle cerebral artery located within the intraparietal sulcus of the left cerebral hemisphere (Spetzler-Martin grade 2). The venous drainage of the malformation led to a loss of nutrients in the surrounding brain parenchyma (a steal phenomenon), causing the seizures. The patient successfully underwent transarterial endovascular embolization with Onyx, which proved to be partial on a postoperative angiography, and refused further embolization procedures. There were no postoperative complications to be mentioned. The patient reported no seizures or sleep disturbances at the 12-month follow-up, with sporadic weak headaches remaining. cAVMs remain a pathology with significant morbidity and mortality when undiagnosed. Symptomatic cAVMs leading to a steal phenomenon and seizures can be reliably managed via endovascular embolization alone when the malformation has an appropriate angioarchitecture, location, size, and a low Spetzler-Martin score. However, further inquiry is required into the use of partial embolization in cases where further multiple-stage embolization procedures are declined and/or complete occlusion of the lesion is unfeasible. This case report emphasizes that partial endovascular embolization can be successfully utilized as a treatment modality for the symptoms caused by a steal phenomenon of the venous drainage of a cAVM, such as seizure disorders and migraines, in the rare instance when multiple-stage embolization is declined by the patient and occlusion of the lesion remains subtotal.

Study of vascular sclerosing agent based on the dual mechanism of vascular endothelial cell damage-plasmin system inhibition

Venous malformations are a vascular disorder. Currently, the use of chemical sclerosing agents is a common clinical approach for the treatment of venous malformations. However, the effectiveness of existing sclerosing agents is unsatisfactory and often accompanied by severe side effects. In this study, we have developed a novel cationic surfactant-based sclerosing agent (POL-TA) by conjugating the plasmin inhibitor tranexamic acid (TA) with a nonionic surfactant polidocanol (POL) through an ester bond. POL-TA induces endothelial cell damage, triggering the coagulation cascade and thrombus formation. Moreover, it releases TA in vivo, which inhibits plasmin activity and the activation of matrix metalloproteinase (MMPs), thereby stabilizing the fibrin network of the thrombus and promoting vascular fibrosis. We have established a cell model using venous malformation endothelial cells and assessed the cellular damage and underlying mechanisms of POL-TA. The inhibitory effects of POL-TA on the plasmin-MMPs system were evaluated using MMP-9 activity assay kit. Additionally, the mice tail vein model was employed to investigate the vascular sclerosing effects and mechanisms of POL-TA.

Hepatic arteriovenous malformation in a calf

A case of hepatic arteriovenous malformation is described in a calf that presented with a marked increase in abdominal volume and died 12 h after birth. At necropsy, the calf had marked abdominal distension and haemoperitoneum. The left hepatic lobe was reduced in size and covered by slightly whitish and intensely vascularized membranous tissue. At the edge of the left lobe there were cystic structures filled with translucent fluid. On cut surface, there were multiple cavitations well delimited by whitish walls and multiple dilated blood vessels that communicated with the cavitations. Histopathology revealed an increase in the number of vascular structures of variable calibre within loose fibrous connective tissue. The diagnosis of hepatic arteriovenous malformation was based on the lesions and confirmed by immunohistochemistry. Hepatic arteriovenous malformations are rare in all species, have not been described in cattle and should be included as a cause of mortality in neonates with post-partum haemoperitoneum.

Current Evaluation of Intracerebral Hemorrhage

Advanced imaging is currently critical in diagnosing, predicting, and managing intracerebral hemorrhage. MD CT angiography has occupied the first line of evaluating patients with a clinical diagnosis of a stroke, given its rapid acquisition time, high resolution of vascular structures, and sensitivity for secondary causes of ICH.

Shaping the brain vasculature in development and disease in the single-cell era

The CNS critically relies on the formation and proper function of its vasculature during development, adult homeostasis and disease. Angiogenesis - the formation of new blood vessels - is highly active during brain development, enters almost complete quiescence in the healthy adult brain and is reactivated in vascular-dependent brain pathologies such as brain vascular malformations and brain tumours. Despite major advances in the understanding of the cellular and molecular mechanisms driving angiogenesis in peripheral tissues, developmental signalling pathways orchestrating angiogenic processes in the healthy and the diseased CNS remain incompletely understood. Molecular signalling pathways of the 'neurovascular link' defining common mechanisms of nerve and vessel wiring have emerged as crucial regulators of peripheral vascular growth, but their relevance for angiogenesis in brain development and disease remains largely unexplored. Here we review the current knowledge of general and CNS-specific mechanisms of angiogenesis during brain development and in brain vascular malformations and brain tumours, including how key molecular signalling pathways are reactivated in vascular-dependent diseases. We also discuss how these topics can be studied in the single-cell multi-omics era.

Genetics of brain arteriovenous malformations and cerebral cavernous malformations

Cerebrovascular malformations comprise abnormal development of cerebral vasculature. They can result in hemorrhagic stroke due to rupture of lesions as well as seizures and neurological defects. The most common forms of cerebrovascular malformations are brain arteriovenous malformations (bAVMs) and cerebral cavernous malformations (CCMs). They occur in both sporadic and inherited forms. Rapidly evolving molecular genetic methodologies have helped to identify causative or associated genes involved in genesis of bAVMs and CCMs. In this review, we highlight the current knowledge regarding the genetic basis of these malformations.

A rare association of arteriovenous malformation of the omentum and pseudo-Meigs' syndrome: case report and scoping review of literature

Meigs' syndrome is defined as a secondary triad of ascites, pleural effusion and benign ovarian tumor, usually fibroma. While pseudo-Meigs' syndrome is a rare condition that is associated with benign ovarian tumor-other than fibroma-or even malignant. The case presented is a 40-year-old Saudi, nulliparous woman who was referred for precise diagnostic work-up as a case of huge pelvic-abdominal mass, tense ascites and pleural effusion. After further investigations cancer antigen-125 was found to be elevated. An abdominal CT scan revealed significant interval increase in the size of ascites, which cause huge abdominal distention, as well as a significant pleural effusion. Pathology of surgical specimens revealed a giant uterine leiomyoma, whereas the omentum excision surprisingly confirmed multiple disorganized arteries and veins, which resulted in omental arteriovenous malformation. To the best of our knowledge, this is the first reported case in the worldwide literature of two different rare conditions.

Molecular and genetic mechanisms in brain arteriovenous malformations: new insights and future perspectives

Brain arteriovenous malformations (bAVMs) are rare vascular lesions made of shunts between cerebral arteries and veins without the interposition of a capillary bed. The majority of bAVMs are asymptomatic, but some may be revealed by seizures and potentially life-threatening brain hemorrhage. The management of unruptured bAVMs remains a matter of debate. Significant progress in the understanding of their pathogenesis has been made during the last decade, particularly using genome sequencing and biomolecular analysis. Herein, we comprehensively review the recent molecular and genetic advances in the study of bAVMs that not only allow a better understanding of the genesis and growth of bAVMs, but also open new insights in medical treatment perspectives.

Case Report: A Rare Abdominopelvic Arteriovenous Malformation: Originating From Splenic Artery and Draining Into Portal Vein

Background

Abdominopelvic arteriovenous malformation is an uncommon congenital vascular lesion, for which the diagnosis and treatment are usually difficult. Though embolization and sclerotherapy are the primary treatment strategies, traditional surgical resection remains a valuable option.

Case Presentation

Herein, we present a 32-year-old female diagnosed with a massive abdominopelvic arteriovenous malformation that originates from the splenic artery and drains into the portal vein. The vascular lesion was evaluated with multiple imaging modalities and then surgically resected successfully. The patient was discharged post-operatively on day 6 and free of symptoms during the 12-month follow-up.

Conclusion

To our knowledge, the presented abdominopelvic arteriovenous malformation is the first to be reported in the literature, with such a rare condition originating from the splenic artery and draining into the portal vein.

Quantitative analysis of retinal intermediate and deep capillary plexus in patients with retinal deep vascular complex ischemia

AIM

To quantitatively analyze the retinal intermediate and deep capillary plexus (ICP and DCP) in patients with retinal deep vascular complex ischemia (RDVCI), using 3D projection artifacts removal (3D PAR) optical coherence tomography angiography (OCTA).

METHODS

RDVCI patients and gender- and age-matched healthy controls were assessed and underwent OCTA examinations. The parafoveal vessel density (PFVD) of retinal deep vascular complex (DVC), ICP, and DCP were analyzed, and the percentage of reduction (PR) of PFVD was calculated.

RESULTS

Twenty-four eyes in 22 RDVCI patients (20 in acute phase and 4 in chronic phase) and 24 eyes of 22 healthy subjects were enrolled as the control group. Significant reduction of PFVD in DVC, ICP, and DCP was observed in comparison with the controls (DVC: acute: 43.59%±6.58% vs 49.92%±5.49%, PR=12.69%; chronic: 43.50%±3.33% vs 51.20%±3.80%, PR=15.04%. ICP: acute: 40.28%±7.91% vs 46.97%±7.14%, PR=14.23%; chronic: 41.48%±2.87% vs 46.43%±3.29%, PR=10.66%. DCP: acute: 45.44%±8.27% vs 51.51%±9.97%, PR=11.79%; chronic: 37.78%±3.48% vs 51.73%±5.17%, PR=26.97%; all P<0.05). No significant PR difference was found among DVC, ICP, and DCP of RDVCI in acute phase (P=0.812), but significant difference in chronic phase (P=0.006, DVC vs DCP, ICP vs DCP). No significant difference in PR between acute and chronic phases in the DVC (P=0.735) or ICP (P=0.681) was found, but significant difference in the DCP (P=0.041).

CONCLUSION

The PFVD of DVC, ICP, and DCP in RDVCI is significantly decreased in both acute and chronic phases. ICP impairment is stabilized from acute to chronic phase in RDVCI, whereas subsequent DCP impairment is uncovered and can be explained by ischemia-reperfusion damage.

Endovascular balloon-assisted liquid embolisation of soft tissue vascular malformations: technical feasibility and safety

Purpose

Arteriovenous malformations (AVMs) are abnormal communications between arteries and veins without an intervening capillary system. The best endovascular treatment option for these is unclear and may involve multiple staged procedures using a variety of embolic materials. We report our initial experience using a modified version of a previously published neurointerventional technique to treat soft tissue AVMs with single-stage curative intent.

Materials and methods

Soft tissue AVMs treated endovascularly using either sole arterial or combined arterial and venous balloon-assisted techniques with liquid embolic agents were retrospectively identified over a 3.5 year period (January 2017 to June 2020)) at two centres. Clinical, pre-operative radiological, procedural technical and post treatment details were recorded.

Results

Seven patients were treated for symptomatic soft tissue arteriovenous malformations. These AVMs were located in the peripheral limbs (five), tongue (one) and uterus (one). Curative treatment was achieved in 6/7 patients with one patient requiring a second treatment approximately 1 year later. A variety of liquid embolisation agents (LEAs) including sclerosants and polymers were used. Clinical success rate was 100% following treatment. One patient experienced expected temporary post-operative tongue swelling requiring tracheostomy occurred following embolisation of the lingual AVM. A minor complication in a second patient was due to an access site haematoma developed following treatment of the hand AVM requiring surgical intervention. No long-term sequelae or additional complications were observed.

Conclusion

Endovascular arterial and venous balloon assisted LEA embolization of soft tissue AVMs with curative intent is feasible. This technique may provide an alternative treatment option for achieving durable occlusion for complex soft tissue AVMs.

To be or not to be: endothelial cell plasticity in development, repair, and disease

Endothelial cells display an extraordinary plasticity both during development and throughout adult life. During early development, endothelial cells assume arterial, venous, or lymphatic identity, while selected endothelial cells undergo additional fate changes to become hematopoietic progenitor, cardiac valve, and other cell types. Adult endothelial cells are some of the longest-lived cells in the body and their participation as stable components of the vascular wall is critical for the proper function of both the circulatory and lymphatic systems, yet these cells also display a remarkable capacity to undergo changes in their differentiated identity during injury, disease, and even normal physiological changes in the vasculature. Here, we discuss how endothelial cells become specified during development as arterial, venous, or lymphatic endothelial cells or convert into hematopoietic stem and progenitor cells or cardiac valve cells. We compare findings from in vitro and in vivo studies with a focus on the zebrafish as a valuable model for exploring the signaling pathways and environmental cues that drive these transitions. We also discuss how endothelial plasticity can aid in revascularization and repair of tissue after damage- but may have detrimental consequences under disease conditions. By better understanding endothelial plasticity and the mechanisms underlying endothelial fate transitions, we can begin to explore new therapeutic avenues.

Towards precision nanomedicine for cerebrovascular diseases with emphasis on Cerebral Cavernous Malformation (CCM)

Introduction: Cerebrovascular diseases encompass various disorders of the brain vasculature, such as ischemic/hemorrhagic strokes, aneurysms, and vascular malformations, also affecting the central nervous system leading to a large variety of transient or permanent neurological disorders. They represent major causes of mortality and long-term disability worldwide, and some of them can be inherited, including Cerebral Cavernous Malformation (CCM), an autosomal dominant cerebrovascular disease linked to mutations in CCM1/KRIT1, CCM2, or CCM3/PDCD10 genes.Areas covered: Besides marked clinical and etiological heterogeneity, some commonalities are emerging among distinct cerebrovascular diseases, including key pathogenetic roles of oxidative stress and inflammation, which are increasingly recognized as major disease hallmarks and therapeutic targets. This review provides a comprehensive overview of the different clinical features and common pathogenetic determinants of cerebrovascular diseases, highlighting major challenges, including the pressing need for new diagnostic and therapeutic strategies, and focusing on emerging innovative features and promising benefits of nanomedicine strategies for early detection and targeted treatment of such diseases.Expert opinion: Specifically, we describe and discuss the multiple physico-chemical features and unique biological advantages of nanosystems, including nanodiagnostics, nanotherapeutics, and nanotheranostics, that may help improving diagnosis and treatment of cerebrovascular diseases and neurological comorbidities, with an emphasis on CCM disease.

Detection of p62/SQSTM1 Aggregates in Cellular Models of CCM Disease by Immunofluorescence

Cerebral cavernous malformations (CCM) is a familial or sporadic rare disorder that is characterized by capillary vascular lesions with a mulberry-like appearance on MRI scans. Three distinct genes have been associated to CCM disease, known as CCM1/KRIT1, CCM2/MGC4607, and CCM3/PDCD10. Loss-of-functions mutations on these genes lead to deregulation in multiple signaling pathways, thereby resulting in disturbed vessel organization and function. Insufficient autophagy has been observed upon downregulation of all three CCM genes, both in cells and human patient tissues, revealed as aberrant accumulation of the autophagy receptor p62/SQSTM1. The autophagic process is conceived as an adaptive response to stress and is essential for the maintenance of cellular homeostasis. The aim of this review is to briefly summarize the current knowledge on the role of autophagy in CCM disease and to furnish a detailed protocol for detecting and measuring p62/SQSTM1 cytoplasmic aggregates through immunofluorescence technique.

Cerebellar Arteriovenous Malformation Rupture Despite Apparent Angiographic Obliteration

BACKGROUND

Arteriovenous malformations (AVMs) can occur in all regions of the brain and spinal cord, with clinical consequences and risks varying by location. Delayed AVM rupture despite digital subtraction angiography-confirmed obliteration post-radiation is exceedingly rare.

CASE DESCRIPTION

To our knowledge, we present the first documented case of delayed hemorrhage associated with a cerebellar AVM 5 years after linear accelerator-based radiation in a man aged 31 years despite apparent angiographic obliteration.

CONCLUSIONS

Intracranial hemorrhage after radiosurgery in digital subtraction angiography-confirmed obliterated AVMs is rare, with limited understanding of risk factors, appropriate preventative management, and mechanisms of occurrence. This case serves to demonstrate the need for greater awareness of this rare complication, as well as the need for appropriate surveillance and management strategies.

Endovascular embolization of canine hepatic arteriovenous malformations using precipitating hydrophobic injectable liquid (PHIL) liquid embolic agent: a proof of concept study

Background

Hepatic arteriovenous malformations (HAVMs) are rare congenital lesions consisting of multiple high-pressure arteries feeding into low-pressure veins via a central nidus. Massive haemorrhage, portal hypertension and hepatic insufficiency can ensue. Endovascular embolization is increasingly a first line treatment method although there is no general consensus or guidelines on the most effective embolic agent or approach. We describe the novel treatment of two dogs with congenital hepatic AVMs using a modified version of the ‘pressure cooker’ technique often utilised in neurointervention with the DMSO-based PHIL embolic agent delivered via the DMSO compatible Scepter-XC dual lumen balloon catheter.

Case presentation

Two paediatric dogs were diagnosed with hepatic AVMs. Both dogs presented with ascites and abnormal liver function tests. CT angiograms revealed hepatic arterio-portal malformations arising from an enlarged celiac artery. Selective catheterisation of the artery supplying the AVM was achieved via a femoral artery approach. A Scepter XC dual-lumen compliant balloon microcatheter and Traxcess 0.014 guidewire combination was advanced to the nidus via through the 5Fr guide catheter towards the nidus. Inflation of the balloon occluded arterial inflow and PHIL was injected under continuous fluoroscopic screening until the PHIL embolic agent penetrated into the draining portal vein beyond the nidus.

In patient 1, normal portal venous waveform was restored with reversal of severe hepatic insufficiency. Whilst there was initial improvement post-operatively in patient 2 with normalisation of portal vein pressures and flow, opening of collateral nidus vessels re-established the high-pressure communication, and euthanasia was elected by the owner.

Conclusions

The ‘pressure cooker’ technique is a safe and efficacious approach to the treatment of canine HAVMs. The novel use of PHIL and the Scepter XC balloon catheter has several advantages over conventional endovascular approaches. Translational application to human paediatric interventions for similar conditions where embolic and contrast agent volume constraints are similar can be considered.

Venous identity requires BMP signalling through ALK3

Venous endothelial cells are molecularly and functionally distinct from their arterial counterparts. Although veins are often considered the default endothelial state, genetic manipulations can modulate both acquisition and loss of venous fate, suggesting that venous identity is the result of active transcriptional regulation. However, little is known about this process. Here we show that BMP signalling controls venous identity via the ALK3/BMPR1A receptor and SMAD1/SMAD5. Perturbations to TGF-β and BMP signalling in mice and zebrafish result in aberrant vein formation and loss of expression of the venous-specific gene Ephb4, with no effect on arterial identity. Analysis of a venous endothelium-specific enhancer for Ephb4 shows enriched binding of SMAD1/5 and a requirement for SMAD binding motifs. Further, our results demonstrate that BMP/SMAD-mediated Ephb4 expression requires the venous-enriched BMP type I receptor ALK3/BMPR1A. Together, our analysis demonstrates a requirement for BMP signalling in the establishment of Ephb4 expression and the venous vasculature.

The establishment of functional vasculatures requires the specification of newly formed vessels into veins and arteries. Here, Neal et al. use a combination of genetic approaches in mice and zebrafish to show that BMP signalling, via ALK3 and SMAD1/5, is required for venous specification during blood vessel development.

Endothelial-Vascular Smooth Muscle Cells Interactions in Atherosclerosis

Atherosclerosis is a chronic progressive inflammatory process that can eventually lead to cardiovascular disease (CVD). Despite available treatment, the prevalence of atherosclerotic CVD, which has become the leading cause of death worldwide, persists. Identification of new mechanisms of atherogenesis are highly needed in order to develop an effective therapeutic treatment. The blood vessels contain two primary major cell types: endothelial cells (EC) and vascular smooth muscle cells (VSMC). Each of these performs an essential function in sustaining vascular homeostasis. EC-VSMC communication is essential not only to development, but also to the homeostasis of mature blood vessels. Aberrant EC-VSMC interaction could promote atherogenesis. Identification of the mode of EC-VSMC crosstalk that regulates vascular functionality and sustains homeostasis may offer strategic insights for prevention and treatment of atherosclerotic CVD. Here we will review the molecular mechanisms underlying the interplay between EC and VSMC that could contribute to atherosclerosis. We also highlight open questions for future research directions.

Excess vascular endothelial growth factor-A disrupts pericyte recruitment during blood vessel formation

Pericyte investment into new blood vessels is essential for vascular development such that mis-regulation within this phase of vessel formation can contribute to numerous pathologies including arteriovenous and cerebrovascular malformations. It is critical therefore to illuminate how angiogenic signaling pathways intersect to regulate pericyte migration and investment. Here, we disrupted vascular endothelial growth factor-A (VEGF-A) signaling in ex vivo and in vitro models of sprouting angiogenesis, and found pericyte coverage to be compromised during VEGF-A perturbations. Pericytes had little to no expression of VEGF receptors, suggesting VEGF-A signaling defects affect endothelial cells directly but pericytes indirectly. Live imaging of ex vivo angiogenesis in mouse embryonic skin revealed limited pericyte migration during exposure to exogenous VEGF-A. During VEGF-A gain-of-function conditions, pericytes and endothelial cells displayed abnormal transcriptional changes within the platelet-derived growth factor-B (PDGF-B) and Notch pathways. To further test potential crosstalk between these pathways in pericytes, we stimulated embryonic pericytes with Notch ligands Delta-like 4 (Dll4) and Jagged-1 (Jag1) and found induction of Notch pathway activity but no changes in PDGF Receptor-β (Pdgfrβ) expression. In contrast, PDGFRβ protein levels decreased with mis-regulated VEGF-A activity, observed in the effects on full-length PDGFRβ and a truncated PDGFRβ isoform generated by proteolytic cleavage or potentially by mRNA splicing. Overall, these observations support a model in which, during the initial stages of vascular development, pericyte distribution and coverage are indirectly affected by endothelial cell VEGF-A signaling and the downstream regulation of PDGF-B-PDGFRβ dynamics, without substantial involvement of pericyte Notch signaling during these early stages.

[Cavernomas of the central nervous system : Observational study of 111 patients]

PURPOSE

The prevalence of cavernomas (cavernous hemangioma) is 0.1-0.7%. Cavernomas are often found as an incidental finding within the framework of magnetic resonance imaging (MRI) examinations in mainly young and healthy patients. In the literature, the reported risk of hemorrhage varies greatly and is sometimes higher than that of aneurysms, which is surprising given that cavernomas are part of the low blood pressure system. After the diagnosis the medical practitioner and the patient have to decide on the further therapy, either surgical removal or the strategy of watchful waiting (conservative treatment). The aim of our study was to determine the frequency of bleeding of cavernomas and the consequences and to determine the satisfaction of patients with treatment. All these aspects should make the therapeutic decision easier for medical practitioners.

MATERIAL AND METHODS

The study included all patients who were treated in the military hospital in Ulm during the period 2002-2012 and with the diagnosis of one or more cavernomas of the central nervous system (CNS) detected by MRI. This resulted in a total number of 111 patients. We recorded the epidemiological data and analyzed all cavernomas with respect to the location, size, treatment, side effects, etc. Furthermore, all included patients were sent a comprehensive questionnaire about symptoms, course of the disease and the quality of life. The response rate was 38%. All the collected data were analyzed with respect to the various aspects.

RESULTS

Depending on the definition of a bleeding event of a cavernoma and selection of the observational period, the probability of a hemorrhage risk ranged from 1.3% to 5.9% per patient year. This relatively high proportion is, however, put into perspective by the mostly mild consequences of a bleeding event. Many cavernomas, which were detected as an incidental finding showed signs of previous bleeding but the patients remained free of symptoms. Additionally, there was no patient in this collective who suffered serious consequences due to a bleeding event. Of the patients with temporal cavernomas 45% had symptomatic epilepsy. The results of the patient survey were heterogeneous. Some patients stated that in retrospect they would not choose surgical treatment again.

CONCLUSION

As a result of our findings we think it is important to critically look at the indications for surgical removal of cavernomas and special attention must be paid to informed consent of the patient. The frequent appearance of temporal cavernomas and their propensity to epileptic seizures is an essential aspect, which certainly influences the therapeutic decision. Although cavernomas are a venous malformation in the low blood pressure system, the determined frequency of hemorrhage was 5.9%, which was higher than expected but which is confirmed by other studies. Reports on severe sequelae of cavernoma bleeding are also rare in the literature, which relativizes the resulting danger of the relatively high probability of hemorrhage.

Blood flow controls bone vascular function and osteogenesis

While blood vessels play important roles in bone homeostasis and repair, fundamental aspects of vascular function in the skeletal system remain poorly understood. Here we show that the long bone vasculature generates a peculiar flow pattern, which is important for proper angiogenesis. Intravital imaging reveals that vessel growth in murine long bone involves the extension and anastomotic fusion of endothelial buds. Impaired blood flow leads to defective angiogenesis and osteogenesis, and downregulation of Notch signalling in endothelial cells. In aged mice, skeletal blood flow and endothelial Notch activity are also reduced leading to decreased angiogenesis and osteogenesis, which is reverted by genetic reactivation of Notch. Blood flow and angiogenesis in aged mice are also enhanced on administration of bisphosphonate, a class of drugs frequently used for the treatment of osteoporosis. We propose that blood flow and endothelial Notch signalling are key factors controlling ageing processes in the skeletal system.

Formation of new blood vessels and bone is coupled. Here the authors show that blood flow represents a key regulator of angiogenesis and endothelial Notch signalling in the bone, and that reactivation of Notch signalling in the endothelium of aged mice rejuvenates the bone.

Phosphoinositide 3-kinase: a new kid on the block in vascular anomalies

Vascular anomalies are broadly divided into vascular tumours and malformations. These lesions are composed of abnormal vascular elements of various types, and mainly affect infants, children, and young adults. Vascular anomalies may be painful, may be complicated by bleeding, infection, or organ dysfunction, and can have secondary effects on other tissues. Current treatment strategies include surgical excision, pulsed laser, and sclerotherapy, which are invasive, with risks of recurrence. There are growing pharmacological options for these vascular anomalies, but, to date, no specific targeted therapies have been developed. Phosphoinositide 3-kinases (PI3Ks) constitute a family of lipid kinases that are involved in signal transduction and vesicular traffic, and that modulate important cellular processes such as proliferation, growth, and migration. Recent findings have indicated that the PI3K signalling pathway is important in the pathogenesis of vascular anomalies. This provides an opportunity to use PI3K inhibitors, which are in clinical trials for cancer treatment, for such lesions. Here, we provide an update on the classification of vascular anomalies, with their major features, and discuss the role of the PI3K signalling pathway in the pathogenesis of vascular anomalies, and their clinical implications and therapeutic opportunities. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Biological relevance of tissue factor and IL-6 in arteriovenous malformations

Arteriovenous malformations (AVMs) are congenital abnormal vessels that shunt blood directly from the arterial to the venous system without a capillary bed. The underlying pathology of AVMs is not fully understood. The objective of the study was to determine the association between the expression patterns of tissue factor (TF) and interleukin-6 (IL-6) in AVMs with clinical and pathological findings. Eighteen cases of sporadic AVM with operative specimens were included in this study. The expression of messenger RNA (mRNA) of TF and IL-6 was assayed, and association with clinical factors was investigated. The distribution of TF and IL-6 was examined with immunofluorescence. The mRNA expression of TF was significantly higher in AVM specimens than in control tissues (P = 0.002) and significantly higher in the symptomatic group than in the asymptomatic group (P = 0.037). The mRNA expression of IL-6 was likewise significantly higher in AVM specimens than in control tissues (P = 0.038). Examination of immunostained sections indicated that TF⁺ cells were also positive for IL-6 and were distributed around normal endothelial cells and pericytes. Moreover, TF⁺/IL-6⁺ cells also expressed CD31, vascular endothelial growth factor receptor 2 (VEGFR2), and platelet-derived growth factor receptor beta (PDGFR-beta). These results suggest that TF is elevated in AVMs and that it mediates symptomatic events. IL-6 is associated with the angiogenic activity of TF, and both are present in the same abnormal endothelial cells and pericytes. These factors may have interactive effects and may serve in a prognostic role for AVMs.

Trigeminal neuralgia caused by brain arteriovenous malformations: A case report and literature review

Few cases of trigeminal neuralgia (TGN) induced by brain arteriovenous malformations (bAVMs) have previously been reported. The present case report described one case of TGN caused by bAVMs in a 32-year-old male patient who suffered from recurrent pain in his right cheek for a period of two years, for whom the seizure frequency and duration of pain increased for 6 months. Magnetic resonance imaging was performed, which demonstrated flow-void signals in the abnormal vessels in the right cerebellopontine angle. Subsequent digital subtraction angiography confirmed the diagnosis of bAVMs, and showed the nidus was fed by the right superior cerebellar and the right anterior inferior cerebellar, and drained into the adjacent venous sinuses on the same side. The patient underwent an interventional embolization treatment. TGN was completely relieved following embolization of the majority of the bAVMs. Pain relief may be associated with blocking of the pulsatile compression of the feeding arteries of the bAVMs, the arterialized draining veins or the malformed niduses following embolization, which is similar to the effects induced by microvascular decompression surgery of the trigeminal nerve. In the present case study and review, the underlying mechanism and treatment strategy of TGN caused by bAVMs were discussed in the context of present case, and a literature review was carried out.

Ultrasound diagnosis and management of acquired uterine enhanced myometrial vascularity/arteriovenous malformations

BACKGROUND

Arteriovenous malformation is a short circuit between an organ's arterial and venous circulation. Arteriovenous malformations are classified as congenital and acquired. In the uterus, they may appear after curettage, cesarean delivery, and myomectomy among others. Their clinical feature is usually vaginal bleeding, which may be severe, if curettage is performed in unrecognized cases. Sonographically on 2-dimensional grayscale ultrasound scanning, the pathologic evidence appears as irregular, anechoic, tortuous, tubular structures that show evidence of increased vascularity when color Doppler is applied. Most of the time they resolve spontaneously; however, if left untreated, they may require involved treatments such as uterine artery embolization or hysterectomy. In the past, uterine artery angiography was the gold standard for the diagnosis; however, ultrasound scanning has diagnosed successfully and helped in the clinical management. Recently, arteriovenous malformations have been referred to as enhanced myometrial vascularities.

OBJECTIVES

The purpose of this study was to evaluate the role of transvaginal ultrasound scanning in the diagnosis and treatment of acquired enhanced myometrial vascularity/arteriovenous malformations to outline the natural history of conservatively followed vs treated lesions.

METHODS

This was a retrospective study to assess the presentation, treatment, and clinical pictures of patients with uterine Enhanced myometrial vascularity/arteriovenous malformations that were diagnosed with transvaginal ultrasound scanning. We reviewed both (1) ultrasound data (images, measured dimensions, and Doppler blood flow that were defined by its peak systolic velocity and (2) clinical data (age, reproductive status, clinical presentation, inciting event or procedure, surgical history, clinical course, time intervals that included detection to resolution or detection to treatment, and treatment rendered). The diagnostic criteria were "subjective" with a rich vascular network in the myometrium with the use of color Doppler images and "objective" with a high peak systolic velocity of ≥20 cm/sec in the vascular web. Statistical analysis was performed and coded with statistical software where necessary.

RESULTS

Twenty-seven patients met the diagnostic criteria of uterine enhanced myometrial vascularity/arteriovenous malformation. Mean age was 31.8 years (range, 18-42 years). Clinical diagnoses of the patients included 10 incomplete abortions, 6 missed abortions, 5 spontaneous complete abortions, 5 cesarean scar pregnancies, and 1 molar pregnancy. Eighty-nine percent of patients had bleeding (n = 24/27), although 1 patient was febrile, and 2 patients were asymptomatic. Recent surgical procedures were performed in 55.5% patients (15/27) that included curettage (n = 10), cesarean deliveries (n = 5), or both (n = 1); 4 patients had a remote history of uterine surgery that included myomectomy. Treatment was varied and included expectant treatment alone in 48% of the patients with serial ultrasound scans and serum human chorionic gonadotropin until resolution (n = 13/27 patients), uterine artery embolization (29.6%; 8/27 patients), methotrexate administration (22.2%; 6/27 patients), hysterectomy (7.4%; 2/27 patients), and curettage (3.7%; 1/27 patients). Three patients required a blood transfusion. Of the 9 patients whose condition required embolization, the conditions of 7 patients resolved after the procedure although 1 patient's condition required operative hysteroscopy and 1 patient's condition required hysterectomy for intractable bleeding. Average peak systolic velocity after embolization in the 9 patients was 85.2 cm/sec (range, 35-170 cm/sec); the average peak systolic velocity of the 16 patients with spontaneous resolution was 58.5 cm/sec (range, 23-90 cm/sec).

CONCLUSIONS

Acquired enhanced myometrial vascularity/arteriovenous malformations occurred after unsuccessful pregnancies or treatment procedures that included uterine curettage, cesarean delivery, or cesarean scar pregnancy. Triage of patients for expectant treatment vs intervention with uterine artery embolization based on their clinical status, which was supplemented by objective measurements of blood velocity measurement in the arteriovenous malformation, appears to be a good predictor of outcome. Ultrasound evaluation of patients with early pregnancy failure and persistent bleeding should be considered for evaluation of a possible enhanced myometrial vascularity/arteriovenous malformation.

The molecular regulation of arteriovenous specification and maintenance

The formation of a hierarchical vascular network, composed of arteries, veins, and capillaries, is essential for embryogenesis and is required for the production of new functional vasculature in the adult. Elucidating the molecular mechanisms that orchestrate the differentiation of vascular endothelial cells into arterial and venous cell fates is requisite for regenerative medicine, as the directed formation of perfused vessels is desirable in a myriad of pathological settings, such as in diabetes and following myocardial infarction. Additionally, this knowledge will enhance our understanding and treatment of vascular anomalies, such as arteriovenous malformations (AVMs). From studies in vertebrate model organisms, such as mouse, zebrafish, and chick, a number of key signaling pathways have been elucidated that are required for the establishment and maintenance of arterial and venous fates. These include the Hedgehog, Vascular Endothelial Growth Factor (VEGF), Transforming Growth Factor-β (TGF-β), Wnt, and Notch signaling pathways. In addition, a variety of transcription factor families acting downstream of, or in concert with, these signaling networks play vital roles in arteriovenous (AV) specification. These include Notch and Notch-regulated transcription factors (e.g., HEY and HES), SOX factors, Forkhead factors, β-Catenin, ETS factors, and COUP-TFII. It is becoming apparent that AV specification is a highly coordinated process that involves the intersection and carefully orchestrated activity of multiple signaling cascades and transcriptional networks. This review will summarize the molecular mechanisms that are involved in the acquisition and maintenance of AV fate, and will highlight some of the limitations in our current knowledge of the molecular machinery that directs AV morphogenesis.

Combined deficiency of Notch1 and Notch3 causes pericyte dysfunction, models CADASIL, and results in arteriovenous malformations

Pericytes regulate vessel stability and pericyte dysfunction contributes to retinopathies, stroke, and cancer. Here we define Notch as a key regulator of pericyte function during angiogenesis. In Notch1^+/−; Notch3^−/− mice, combined deficiency of Notch1 and Notch3 altered pericyte interaction with the endothelium and reduced pericyte coverage of the retinal vasculature. Notch1 and Notch3 were shown to cooperate to promote proper vascular basement membrane formation and contribute to endothelial cell quiescence. Accordingly, loss of pericyte function due to Notch deficiency exacerbates endothelial cell activation caused by Notch1 haploinsufficiency. Mice mutant for Notch1 and Notch3 develop arteriovenous malformations and display hallmarks of the ischemic stroke disease CADASIL. Thus, Notch deficiency compromises pericyte function and contributes to vascular pathologies.

Magnetic resonance susceptibility weighted imaging in neurosurgery: current applications and future perspectives

Susceptibility weighted imaging (SWI) is a relatively new imaging technique. Its high sensitivity to hemorrhagic components and ability to depict microvasculature by means of susceptibility effects within the veins allow for the accurate detection, grading, and monitoring of brain tumors. This imaging modality can also detect changes in blood flow to monitor stroke recovery and reveal specific subtypes of vascular malformations. In addition, small punctate lesions can be demonstrated with SWI, suggesting diffuse axonal injury, and the location of these lesions can help predict neurological outcome in patients. This imaging technique is also beneficial for applications in functional neurosurgery given its ability to clearly depict and differentiate deep midbrain nuclei and close submillimeter veins, both of which are necessary for presurgical planning of deep brain stimulation. By exploiting the magnetic susceptibilities of substances within the body, such as deoxyhemoglobin, calcium, and iron, SWI can clearly visualize the vasculature and hemorrhagic components even without the use of contrast agents. The high sensitivity of SWI relative to other imaging techniques in showing tumor vasculature and microhemorrhages suggests that it is an effective imaging modality that provides additional information not shown using conventional MRI. Despite SWI's clinical advantages, its implementation in MRI protocols is still far from consistent in clinical usage. To develop a deeper appreciation for SWI, the authors here review the clinical applications in 4 major fields of neurosurgery: neurooncology, vascular neurosurgery, neurotraumatology, and functional neurosurgery. Finally, they address the limitations of and future perspectives on SWI in neurosurgery.

We have contact: endothelial cell-smooth muscle cell interactions

Blood vessels are composed of two primary cell types, endothelial cells and smooth muscle cells, each providing a unique contribution to vessel function. Signaling between these two cell types is essential for maintaining tone in mature vessels, and their communication is critical during development, and for repair and remodeling associated with blood vessel growth. This review will highlight the pathways that endothelial cells and smooth muscle cells utilize to communicate during vessel formation and discuss how disruptions in these pathways contribute to disease.

Constitutively active Notch4 receptor elicits brain arteriovenous malformations through enlargement of capillary-like vessels

Arteriovenous (AV) malformation (AVM) is a devastating condition characterized by focal lesions of enlarged, tangled vessels that shunt blood from arteries directly to veins. AVMs can form anywhere in the body and can cause debilitating ischemia and life-threatening hemorrhagic stroke. The mechanisms that underlie AVM formation remain poorly understood. Here, we examined the cellular and hemodynamic changes at the earliest stages of brain AVM formation by time-lapse two-photon imaging through cranial windows of mice expressing constitutively active Notch4 (Notch4*). AVMs arose from enlargement of preexisting microvessels with capillary diameter and blood flow and no smooth muscle cell coverage. AV shunting began promptly after Notch4* expression in endothelial cells (ECs), accompanied by increased individual EC areas, rather than increased EC number or proliferation. Alterations in Notch signaling in ECs of all vessels, but not arteries alone, affected AVM formation, suggesting that Notch functions in the microvasculature and/or veins to induce AVM. Increased Notch signaling interfered with the normal biological control of hemodynamics, permitting a positive feedback loop of increasing blood flow and vessel diameter and driving focal AVM growth from AV connections with higher blood velocity at the expense of adjacent AV connections with lower velocity. Endothelial expression of constitutively active Notch1 also led to brain AVMs in mice. Our data shed light on cellular and hemodynamic mechanisms underlying AVM pathogenesis elicited by increased Notch signaling in the endothelium.

The use of sodium tetradecyl sulphate for the treatment of venous malformations of the head and neck

INTRODUCTION

Vascular malformations have devastating cosmetic effects in addition to being associated with pain and bleeding. Sclerotherapy has been used as an effective therapeutic modality for the management of vascular malformations. The purpose of this case series is to describe our clinical experience of using sodium tetradecyl sulphate (STS) 3 % in the treatment of venous malformation lesions of head and neck.

MATERIALS AND METHODS

Thirteen patients were included in this study (three male and ten female; age range between 8 months and 54 years; mean age 18.2 years, ±SD 15.71). The patients were treated by 3 % STS intralesional injections. Of the thirteen patients treated, complete resolution occurred in four patients (28.57 %), a good response occurred in five patients (35.7 %), a moderate response in two patients (14.28 %), a mild response in two patients (14.28 %) and no response in one patient (7.14 %). The side effects encountered in all patients were pain and edema after injection which was controlled by oral analgesics and an intramuscular injection of dexamethasone. In addition, two patients developed a superficial ulceration (11.76 %) which healed uneventfully, and one patient developed ecchymosis after injection (5.88 %).

CONCLUSION

Sclerotherapy with 3 % STS is a simple, safe, and effective modality for the treatment of venous malformations.