Expression of angiogenesis factors and selected vascular wall matrix proteins in intracranial saccular aneurysms

Solid vs. cystic predominance in posterior fossa hemangioblastomas: implications for cerebrovascular risks and patient outcome

BACKGROUND

Hemangioblastomas (HGBs) are highly vascular benign tumors, commonly located in the posterior fossa, and 80% of them are sporadic. Patients usually present with features of raised intracranial pressure and cerebellar symptoms. HGB can be classified as either mostly cystic or solids. Although the solid component is highly vascularized, aneurysm or hemorrhagic presentation is rarely described, having catastrophic results.

METHODS

We identified 32 consecutive patients with posterior fossa HBG who underwent surgery from 2008 through 2020 at our medical center. Tumors were classified as predominantly cystic or solid according to radiological features. Resection was defined as gross total (GTR) or subtotal (STR).

RESULTS

During the study period, 32 posterior fossa HGBs were resected. There were 26 cerebellar lesions and 4 medullar lesions, and in 2 patients, both structures were affected. Predominant cystic tumors were seen in 15 patients and solids in 17. Preoperative digital subtraction angiography (DSA) was performed in 8 patients with solid tumors, and 4 showed tumor-related aneurysms. Embolization of the tumors was performed in 6 patients, including the four tumor-related aneurysms. GTR was achieved in 29 tumors (91%), and subtotal resection in 3 (9%). Three patients had postoperative lower cranial nerve palsy. Functional status was stable in 5 patients (16%), improved in 24 (75%), and 3 patients (9%) deteriorated. One patient died 2 months after the surgery. Two tumors recurred and underwent a second surgery achieving GTR. The mean follow-up was 42.7 months (SD ± 51.0 months).

CONCLUSIONS

Predominant cystic HGB is usually easily treated as the surgery is straightforward. Those with a solid predominance present a more complex challenge sharing features similar to arteriovenous malformations. Given the important vascular association of solid predominance HGB with these added risk factors, the preoperative assessment should include DSA, as in arteriovenous malformations, and endovascular intervention should be considered before surgery.

Genetic polymorphisms and transcription profiles associated with intracranial aneurysm: a key role for NOTCH3

Intracranial aneurysm (IA) incidence is about 1~2%. However, the specific mechanisms of IA onset and development need further study. Our objective was to discover novel IA-related genes to determine possible etiologies further. We performed next-generation sequencing on nineteen Chinese patients with familial IA and one patient with sporadic IA. We obtained mRNA expression data of 129 samples from Gene Expression Omnibus (GEO) and made statistical computing to discover differentially expressed genes (DEGs). The screened IA-related gene NOTCH3 was determined by bioinformatic data mining. We verified the IA-related indicators of NOTCH3. Association was found between IA and the NOTCH3 SNPs rs779314594, rs200504060 and rs2285981. Levels of NOTCH3 mRNA were lower in IA tissue than in control tissue, but higher in peripheral blood neutrophils from IA patients than in neutrophils from controls. Levels of NOTCH3 protein were lower in IA tissue than in cerebral artery tissue. NOTCH3 also decreased the expression of angiogenesis factors in human umbilical vein endothelial cells. Variation in NOTCH3 and alteration of its expression in cerebral artery or neutrophils may contribute to IA. Our findings also describe a bioinformatic-experimental approach that may prove useful for probing the pathophysiology of other complex diseases.

Bilateral and multiple sub-internal limiting membrane hemorrhages in a familial retinal arteriolar tortuosity patient by Valsalva-like mechanism: an observational case report

Background

Bilateral and multiple Valsalva-related sub-internal limiting membrane (ILM) hemorrhages in a familial retinal arteriolar tortuosity (FRAT) patient is rare, and we treated this patient by both observation and Neodymium yttrium aluminum garnet (Nd: YAG) laser membranotomy methods.

Case presentation

A 13-year-old female student presented with sudden visual loss and central scotoma in both eyes after running 800 m at the school gym. The examination revealed six sub-ILM hemorrhages with the biggest hemorrhage measuring approximately 1.5-disc diameters (DD) in the right eye and two sub-ILM hemorrhages with the biggest one measuring 5.5 DD in the left eye. The patient was diagnosed as having Valsalva retinopathy associated with FRAT. Nd: YAG laser membranotomy was performed at the biggest hemorrhages and the rest hemorrhages were treated with observation in both eyes. The visual acuity recovered to 20/16 in the right eye and 20/20 in the left eye. Epiretinal membrane (ERM) formation was observed in the left eye.

Conclusions

Nd: YAG laser could be considered for treating premacular hemorrhage in FRAT patient especially when a quick vision recovery was needed. This is the first reported case of a FRAT patient suffering from bilateral and multiple Valsalva-related sub-ILM hemorrhages which were treated by both observation and Nd: YAG laser treatment.

Alport's syndrome and intracranial aneurysm: mere coincidence or undiscovered causal relationship

A 44-year-old Caucasian man with a history of deceased donor renal transplant for end-stage renal disease from Alport’s syndrome (AS), presented with a spontaneous subarachnoid haemorrhage and hydrocephalus. Following an external ventricular drain for the hydrocephalus, a CT angiography revealed a dissection of the left vertebral artery extending into vertebro-basilar junction necessitating a bypass between left occipital artery to left posterior inferior cerebellar artery. He had a posterior fossa Craniectomy, C1 laminectomy and coiling off, of the left vertebral artery. Postprocedure course was prolonged but uneventful with complete recovery and normal renal function 18 months postpresentation. AS, a disease caused by abnormalities in the synthesis of type IV collagen, can cause aneurysms with severe and permanent neurological sequalae. We present a case of AS with intracranial arterial dissection with potential life-threatening consequences and discuss the genetic and molecular basis of AS along with review of the relevant literature.

Inflammatory changes in the aneurysm wall: a review

Rupture of a saccular intracranial artery aneurysm (IA) causes subarachnoid hemorrhage, a significant cause of stroke and death. The current treatment options, endovascular coiling and clipping, are invasive and somewhat risky. Since only some IAs rupture, those IAs at risk for rupture should be identified. However, to improve the imaging of rupture-prone IAs and improve IA treatment, IA wall pathobiology requires more thorough knowledge. Chronic inflammation has become understood as an important phenomenon in IA wall pathobiology, featuring inflammatory cell infiltration as well as proliferative and fibrotic remodulatory responses. We review the literature on what is known about inflammation in the IA wall and also review the probable mechanisms of how inflammation would result in the degenerative changes that ultimately lead to IA wall rupture. We also discuss current options in imaging inflammation and how knowledge of inflammation in IA walls may improve IA treatment.

Effect of VEGF on Inflammatory Regulation, Neural Survival, and Functional Improvement in Rats following a Complete Spinal Cord Transection

After complete transection of the thoracic spinal segment, neonatal rats exhibit spontaneous locomotor recovery of hindlimbs, but this recovery is not found in adult rats after similar injury. The potential mechanism related to the difference in recovery of neonatal and adult rats remains unknown. In this study, 342 animals were analyzed. The vascular endothelial growth factor (VEGF) level in spinal segments below injury sites was significantly higher in postnatal day 1 rats (P1) compared with 28-day-old adult rats (P28) following a complete T9 transection. VEGF administration in P28 rats with T9 transection significantly improved the functional recovery; by contrast, treatment with VEGF receptor inhibitors in P1 rats with T9 transection slowed down the spontaneous functional recovery. Results showed more neurons reduced in the lumbar spinal cord and worse local neural network reorganization below injury sites in P28 rats than those in P1 rats. Transynaptic tracing with pseudorabies virus and double immunofluorescence analysis indicated that VEGF treatment in P28 rats alleviated the reduced number of neurons and improved their network reorganization. VEGF inhibition in neonates resulted in high neuronal death rate and deteriorated network reorganization. In in vivo studies, T9 transection induced less increase in the number of microglia in the spinal cord in P1 animals than P28 animals. VEGF treatment reduced the increase in microglial cells in P28 animals. VEGF administration in cultured spinal motoneurons prevented lipopolysaccharide (LPS)-induced neuronal death and facilitated neurite growth. Western blots of the samples of lumbar spinal cord after spinal transection and cultured spinal motoneurons showed a lower level of Erk1/2 phosphorylation after the injury or LPS induction compared with that in the control. The phosphorylation level increased after VEGF treatment. In conclusion, VEGF is a critical mediator involved in functional recovery after spinal transection and can be considered a potential target for clinical therapy.

Stromal cell-derived factor-1 promoted angiogenesis and inflammatory cell infiltration in aneurysm walls

OBJECT

A small percentage of cerebral aneurysms rupture, but when they do, the effects are devastating. Current management of unruptured aneurysms consists of surgery, endovascular treatment, or watchful waiting. If the biology of how aneurysms grow and rupture were better known, a novel drug could be developed to prevent unruptured aneurysms from rupturing. Ruptured cerebral aneurysms are characterized by inflammation-mediated wall remodeling. The authors studied the role of stromal cell-derived factor-1 (SDF-1) in inflammation-mediated wall remodeling in cerebral aneurysms.

METHODS

Human aneurysms, murine carotid artery aneurysms, and murine intracranial aneurysms were studied using immunohistochemistry. Flow cytometry analysis was performed on blood from mice developing carotid or intracranial aneurysms. The effect of SDF-1 on endothelial cells and macrophages was studied by chemotaxis cell migration assay and capillary tube formation assay. Anti-SDF-1 blocking antibody was given to mice and compared with control (vehicle)-administered mice for its effects on the walls of carotid aneurysms and the development of intracranial aneurysms.

RESULTS

Human aneurysms, murine carotid aneurysms, and murine intracranial aneurysms all expressed SDF-1, and mice with developing carotid or intracranial aneurysms had increased progenitor cells expressing CXCR4, the receptor for SDF-1 (p < 0.01 and p < 0.001, respectively). Human aneurysms and murine carotid aneurysms had endothelial cells, macrophages, and capillaries in the walls of the aneurysms, and the presence of capillaries in the walls of human aneurysms was associated with the presence of macrophages (p = 0.01). Stromal cell-derived factor-1 promoted endothelial cell and macrophage migration (p < 0.01 for each), and promoted capillary tube formation (p < 0.001). When mice were given anti-SDF-1 blocking antibody, there was a significant reduction in endothelial cells (p < 0.05), capillaries (p < 0.05), and cell proliferation (p < 0.05) in the aneurysm wall. Mice given anti-SDF-1 blocking antibody developed significantly fewer intracranial aneurysms (33% vs 89% in mice given control immunoglobulin G, respectively; p < 0.05).

CONCLUSIONS

These data suggest SDF-1 is associated with angiogenesis and inflammatory cell migration and proliferation in the walls of aneurysms, and may have a role in the development of intracranial aneurysms.

Influence of parent vessel dominancy on fluid dynamics of anterior communicating artery aneurysms

BACKGROUND

Parent vessel plays an important role in aneurysm formation and rupture. The diameter of either the A1 arteries is the peculiar key controlling the flow of the anterior communicating artery (ACOMA) aneurysms (ANs).

OBJECTIVE

The purpose is to study the effect of parent vessel dominancy, that is, the diameter of the A1 artery, on the flow characteristics of the ACOMA ANs.

METHODS

Numerical simulations for the flow patterns in six artificial models have been studied. Three models are designed with aneurysms and three models without. The two A1s were equal in two models. In the other two models, the nondominant A1 diameters were decreased by 50%. Again, the nondominant A1s were decreased by another 50% in the last two models. Each pair was designed with and without aneurysms in the ACOMA.

FINDINGS

The ACOMA shows lower velocity magnitudes and wall shear stresses when the two A1s are equal. However, if one A1 is dominant with a 50% difference from the other A1, there is higher shear stress on the ACOMA itself and in the inflow zone of the aneurysm that increases more with further reduction of the nondominant A1 by another 50%. An area of high corner pressure at the bifurcation of the dominant A1 into the ACOMA and A2 exists and increases in value with the decrease of diameter of the other nondominant A1.

CONCLUSION

Aneurysms located in the ACOMA with differences of 50% or more between the two A1s are subjected to more flow stresses.

Multiple neurotrophic effects of VEGF on cultured neurons

A large literature demonstrates the multifunctional nature of vascular endothelial growth factor (VEGF). Though initially characterized as an endothelial cell-specific factor, recent studies reveal that VEGF has numerous effects on diverse cell types in the brain including neurons. The objective of this study is to examine the effects of VEGF in cultured cortical neurons on survival, p38 mitogen-activated protein kinase (p38 MAP kinase) activity, pro- and anti-apoptotic protein expression and on release of neurotrophic and neurotoxic factors. The results show that VEGF dose-dependently enhances the survival of neurons in culture. VEGF decreases active caspase 3 levels and increases expression of the anti-apoptotic protein Bcl-2. VEGF decreases phosphorylated p38 MAP kinase level and activity in cortical neurons. In addition to modulating survival/death pathways in cortical neurons, VEGF also regulates release of proteins that affect neuronal viability. VEGF causes a dose-dependent release of the neurotrophic protein pigment epithelial-derived factor (PEDF), while significantly decreasing release of the neurotoxic protein amyloid beta. The VEGF-mediated decrease in amyloid beta is dependent on a functional Flt-1 receptor and is inhibited by dicoumarol, a multifunctional inhibitor of stress-activated protein kinase (SAPK)/JNK and NFkappaB pathways. Taken together, these data demonstrate that the neurotrophic effects of VEGF are likely mediated directly by increasing survival and decreasing apoptotic proteins and signals as well as indirectly by modulating release of proteins that affect neuronal viability.

Expression of vascular endothelial growth factor receptor-1/-2 and nitric oxide in unruptured intracranial aneurysms

The biological mechanisms associated with the development and rupture of intracranial aneurysms are not fully understood. To clarify the role of VEGF and the related receptors in the pathophysiology of aneurysm, immunostaining for VEGF, VEGFR1 and VEGFR2 was performed on specimens from six unruptured aneurysms and on two specimens of normal arteries wall as a control. The results were correlated with NO concentration of CSF collected during surgery from 8 patients affected by unruptured aneurysms and in 11 control patients. The immunohistochemical data showed a different pattern of VEGF/VEGFR1/VEGFR2 in aneurysms when compared with control. The results of this preliminary study suggest an imbalance of VEGF, VEGFR1 and VEGFR2, and the interaction of VEGF and NO in the pathophysiology of unruptured aneurysms. Our data support the hypothesis of aneurysm formation associated with a loss of expression of VEGFR1, moderate expression of VEGFR2 and high concentration of nitrate.

Wall enhancement, edema, and hydrocephalus after endovascular coil occlusion of intradural cerebral aneurysms

OBJECT

Symptomatic local inflammation, aseptic meningitis, and hydrocephalus are reported in a group of patients treated with second generation/modified platinum coils. The purpose of this study was to define the frequency and determinants of magnetic resonance (MR) imaging findings of aneurysm wall enhancement, perianeurysmal edema, and hydrocephalus in a cohort of coil-embolized intradural cerebral aneurysms treated with bare platinum or modified platinum coils (Matrix or HydroCoils).

METHODS

The authors retrospectively reviewed 359 Gd-enhanced MR follow-up studies of 181 treated aneurysms (125 ruptured) for mural enhancement. Univariate and multivariate logistic regression analyses were used to define mural enhancement associations with demographic, clinical, angiographic, treatment, and follow-up data. Embolization-related edema and hydrocephalus were defined in 95 MR imaging studies of 56 unruptured aneurysms.

RESULTS

Asymptomatic wall enhancement was observed in lesions treated with all coil types, occurring in 21 (18.6%) of 113 bare platinum coil-treated aneurysms. Independent associations were HydroCoil treatment (odds ratio [OR] 9.75, 95% confidence interval [CI] 3.45-30.75) and increasing aneurysm size (OR 3.58, 95% CI 1.99-6.95). Five (8.9%) unruptured aneurysms had asymptomatic de novo edema, and 3 (5.3%) demonstrated hydrocephalus; all had been treated with HydroCoils. Hydrocephalus presentation was delayed (8-31 months) and symptomatic in 2 patients.

CONCLUSIONS

Asymptomatic aneurysm wall enhancement occurred in 18.6% of embolizations performed with bare platinum coils, and probably represents a normal healing response. Perimural edema and hydrocephalus were observed only in patients treated with HydroCoils, but have been reported in patients treated with other modified platinum coils. These symptoms appear to represent an exaggerated inflammatory response during aneurysm healing. Increased vigilance for delayed hydrocephalus is required. Judicious clinical use of modified platinum coils is warranted until results of randomized trials are published.

COL4A1 mutations and hereditary angiopathy, nephropathy, aneurysms, and muscle cramps

BACKGROUND

COL4A3, COL4A4, and COL4A5 are the only collagen genes that have been implicated in inherited nephropathies in humans. However, the causative genes for a number of hereditary multicystic kidney diseases, myopathies with cramps, and heritable intracranial aneurysms remain unknown.

METHODS

We characterized the renal and extrarenal phenotypes of subjects from three families who had an autosomal dominant hereditary angiopathy with nephropathy, aneurysms, and muscle cramps (HANAC), which we propose is a syndrome. Linkage studies involving microsatellite markers flanking the COL4A1-COL4A2 locus were performed, followed by sequence analysis of COL4A1 complementary DNA extracted from skin-fibroblast specimens from the subjects.

RESULTS

We identified three closely located glycine mutations in exons 24 and 25 of the gene COL4A1, which encodes procollagen type IV alpha1. The clinical renal manifestations of the HANAC syndrome in these families include hematuria and bilateral, large cysts. Histologic analysis revealed complex basement-membrane defects in kidney and skin. The systemic angiopathy of the HANAC syndrome appears to affect both small vessels and large arteries.

CONCLUSIONS

COL4A1 may be a candidate gene in unexplained familial syndromes with autosomal dominant hematuria, cystic kidney disease, intracranial aneurysms, and muscle cramps.

Complex hemodynamics at the apex of an arterial bifurcation induces vascular remodeling resembling cerebral aneurysm initiation

BACKGROUND AND PURPOSE

Arterial bifurcation apices are common sites for cerebral aneurysms, raising the possibility that the unique hemodynamic conditions associated with flow dividers predispose the apical vessel wall to aneurysm formation. This study sought to identify the specific hemodynamic insults that lead to maladaptive vascular remodeling associated with aneurysm development and to identify early remodeling events at the tissue and cellular levels.

METHODS

We surgically created new branch points in the carotid vasculature of 6 female adult dogs. In vivo angiographic imaging and computational fluid dynamics simulations revealed the detailed hemodynamic microenvironment for each bifurcation, which were then spatially correlated with histologic features showing specific tissue responses.

RESULTS

We observed 2 distinct patterns of vessel wall remodeling: (1) hyperplasia that formed an intimal pad at the bifurcation apex and (2) destructive remodeling in the adjacent region of flow acceleration that resembled the initiation of an intracranial aneurysm, characterized by disruption of the internal elastic lamina, loss of medial smooth muscle cells, reduced proliferation of smooth muscle cells, and loss of fibronectin.

CONCLUSIONS

Strong localization of aneurysm-type remodeling to the region of accelerating flow suggests that a combination of high wall shear stress and a high gradient in wall shear stress represents a "dangerous" hemodynamic condition that predisposes the apical vessel wall to aneurysm formation.

Progressive perianeurysmal edema induced after endovascular coil embolization

✓The authors report three cases of progressive vasogenic brain edema surrounding a cerebral aneurysm after endovascular coil embolization. In all three cases embolization was incomplete due to the aneurysms' large sizes and wide necks. Follow-up magnetic resonance imaging revealed de novo vasogenic brain edema surrounding the aneurysms 3 to 6 months after the initial treatment. The edema progressed in parallel with regrowth of the aneurysms. All three aneurysms were deep in the brain parenchyma and showed intramural enhancement, suggesting hemorrhage or inflammation. Each patient underwent a second embolization for the aneurysm regrowth, which resulted in improvement of the edema.

Based on the findings in these cases and review of the literature, it is suggested that incomplete occlusion of larger aneurysms that are deep within the brain may lead to a disorganized intraluminal thrombosis, aneurysm pulsing, and intramural hemorrhage or inflammation, all of which are associated with brain edema following aneurysm recanalization and regrowth. It should be kept in mind that incomplete embolization of larger aneurysms may cause such malignant change and that this complication may occur after endovascular treatment.

Association between an arachnoid cyst and intracranial aneurysms misdiagnosed as a cystic tumor with a mural nodule

✓The authors report on a 63-year-old man initially admitted to an outside hospital for altered mental status and respiratory distress. A head computed tomography scan disclosed a right frontal cystic mass, suspected to be a neoplasm. An open biopsy was performed at an outside institution, and on visualization of the cyst, an aneurysm was found incidentally. Postoperatively, an angiogram and magnetic resonance image confirmed the presence of a distal right M1 segment aneurysm. The patient was transferred to our institution where, in addition to the middle cerebral artery lesion, a right anterior choroidal artery aneurysm was found intraoperatively; the necks of both aneurysms were clipped successfully. A review of the literature revealed 14 additional cases of intracranial aneurysms associated with arachnoid cysts. Data in the present report highlight the importance of considering an intracystic aneurysm in the differential diagnosis when reviewing cases that involve a cystic mass with a mural nodule. The authors provide a comprehensive summary of documented cases of aneurysms associated with arachnoid cysts. In addition, they include a discussion of prevailing thoughts on the origin and evolution of arachnoid cysts.

A proposed parent vessel geometry-based categorization of saccular intracranial aneurysms: computational flow dynamics analysis of the risk factors for lesion rupture

OBJECT

The authors created a simple, broadly applicable classification of saccular intracranial aneurysms into three categories: sidewall (SW), sidewall with branching vessel (SWBV), and endwall (EW) according to the angiographically documented patterns of their parent arteries. Using computational flow dynamics analysis (CFDA) of simple models representing the three aneurysm categories, the authors analyzed geometry-related risk factors such as neck width, parent artery curvature, and angulation of the branching vessels.

METHODS

The authors performed CFDAs of 68 aneurysmal geometric formations documented on angiograms that had been obtained in patients with 45 ruptured and 23 unruptured lesions. In successfully studied CFDA cases, the wall shear stress, blood velocity, and pressure maps were examined and correlated with aneurysm rupture points. Statistical analysis of the cases involving aneurysm rupture revealed a statistically significant correlation between aneurysm depth and both neck size (p < 0.0001) and caliber of draining arteries (p < 0.0001). Wider-necked aneurysms or those with wider-caliber draining vessels were found to be high-flow lesions that tended to rupture at larger sizes. Smaller-necked aneurysms or those with smaller-caliber draining vessels were found to be low-flow lesions that tended to rupture at smaller sizes. The incidence of ruptured aneurysms with an aspect ratio (depth/neck) exceeding 1.6 was 100% in the SW and SWBV categories, whereas the incidence was only 28.75% for the EW aneurysms.

CONCLUSIONS

The application of standardized categories enables the comparison of results for various aneurysms' geometric formations, thus assisting in their management. The proposed classification system may provide a promising means of understanding the natural history of saccular intracranial aneurysms.

A reassessment of vascular endothelial growth factor in central nervous system pathology

✓ Overexpression of vascular endothelial growth factor (VEGF) is associated with several central nervous system (CNS) diseases and abnormalities, and is often postulated as a causative factor and promising therapeutic target in these settings. The authors' goal was to reassess the contribution of VEGF to the biology and pathology of the CNS.

The authors review the literature relating to the following aspects of VEGF: 1) the biology of VEGF in normal brain; 2) the involvement of VEGF in CNS disorders other than tumors (traumatic and ischemic injuries, arteriovenous malformations, inflammation); and 3) the role of VEGF in brain tumor biology (gliomas and the associated vasogenic edema, and hemangioblastomas).

The authors conclude the following: first, that VEGF overexpression contributes to the phenotype associated with many CNS disorders, but VEGF is a reactive rather than a causative factor in many cases; and second, that use of VEGF as a therapeutic agent or target is complicated by the effects of VEGF not only on the cerebral vasculature, but also on astrocytes, neurons, and inflammatory cells. In many cases, therapeutic interventions targeting the VEGF/VEGF receptor axis are likely to be ineffective or even detrimental. Clinical manipulation of VEGF levels in the CNS must be approached with caution.

VEGF plasma levels in non-ruptured intracranial aneurysms

Aneurysm growth appears to be associated with an increased risk of rupture. Therefore, it may be of interest to identify mechanisms contributing to aneurysm growth. Angiogenic factors, particularly vascular endothelial growth factor (VEGF), appear to play an important role in the pathogenesis and growth of cerebrovascular malformations. We aimed to study systemic VEGF levels as a potential systemic marker in patients with non-ruptured intracranial aneurysms compared with healthy controls. Mean VEGF plasma concentrations were found to be increased in patients with non-ruptured intracranial aneurysms compared with healthy controls (85.2 pg/ml versus 44.1 pg/ml). This difference did not reach significance in the analyzed study cohort (p=0.05) but only when the analysis was restricted to male patients (p=0.04). Female patients and controls demonstrated significantly increased VEGF plasma levels only on correlation with age but not with the presence of aneurysms. Neither the presence of multiple aneurysms nor aneurysm location were correlated with VEGF levels. Although overall VEGF plasma difference was not statistically significant, we found significantly increased levels in male patients. Furthermore, we identified a distinct group of female patients with intracranial aneurysms who presented excessively increased VEGF plasma levels to an amount that was not observed in the controls. Further studies may clarify the relationship of aneurysm growth and VEGF.

Enlarging vertebrobasilar nonsaccular intracranial aneurysms: frequency, predictors, and clinical outcome of growth

Object. Vertebrobasilar nonsaccular intracranial aneurysms (NIAs) are characterized by elongation, dilation, and tortuosity of the vertebrobasilar arteries. The goal of this study was to define the frequency, predictors, and clinical outcome of the enlargement of vertebrobasilar NIAs.

Methods. Patients with vertebrobasilar fusiform or dolichoectatic aneurysms demonstrated on imaging studies between 1989 and 2001 were identified. In particular, patients who had undergone serial imaging were included in this study and their medical records were retrospectively reviewed. Prospective information was collected from medical records or death certificates when available. Both initial and serial imaging studies were reviewed. The authors defined NIA enlargement as a change in lesion diameter greater than 2 mm or noted on the neuroradiologist's report. A Cox proportional hazards regression was used to model time from diagnosis of the vertebrobasilar NIA to the first documented enlargement as a function of various predictors. The Kaplan-Meier method was used to study patient death as a function of aneurysm growth.

Of the 159 patients with a diagnosis of vertebrobasilar NIA, 52 had undergone serial imaging studies including 25 patients with aneurysm enlargement. Lesion growth significantly correlated with symptomatic compression at the initial diagnosis (p = 0.0028), lesion type (p < 0.001), and the initial maximal lesion diameter (median 15 mm in patients whose aneurysm enlarged compared with median 8 mm in patients whose aneurysm did not enlarge; p < 0.001). The mortality rate was 5.7 times higher in patients with aneurysm growth than in those with no enlargement after adjustment for patient age (p = 0.002).

Conclusions. Forty-eight percent of vertebrobasilar NIAs demonstrated on serial imaging enlarged, and this growth was associated with significant morbidity and death. Significant risk factors for aneurysm enlargement included symptomatic compression at the initial diagnosis, transitional or fusiform vertebrobasilar NIAs, and initial lesion diameter. Further studies are necessary to determine appropriate treatments of this disease entity once enlargement has been predicted or occurs.

Rapid development of an intranidal aneurysm with perifocal brain edema in an unruptured cerebral arteriovenous malformation. Case report

The authors present the case of a 22-year-old man with an unruptured arteriovenous malformation (AVM) in which an intranidal aneurysm had grown in the course of 3 months and was complicated by perifocal brain edema. A left parietal AVM was incidentally diagnosed on magnetic resonance (MR) imaging. No aneurysms were noted on cerebral angiograms obtained simultaneously. Three months later, T2-weighted MR imaging revealed perifocal brain edema (increased signal intensity in the brain parenchyma adjacent to the nidus). An aneurysm-like signal void was demonstrated in the center of the high-signal area, but no previous hemorrhages could be detected. Angiographic studies revealed an intranidal aneurysm 4 mm in diameter projecting anterolaterally from the nidus. Surgical removal was performed without incident, and no neurological deficits or postoperative complications were observed. An MR image obtained 2 weeks postsurgery revealed complete resolution of the perifocal brain edema. To the authors' knowledge, this is the first reported case of an unruptured AVM in which an intranidal aneurysm with perifocal brain edema developed rapidly (within a few months).

Growth and spontaneous regression of a middle cerebral artery aneurysm after surgical clipping

SUMMARY

We present a case of growth and spontaneous regression of a middle cerebral artery aneurysm after surgical clipping. A 36-year-old woman who presented with grade II subarachnoid haemorrhage was found to have a right middle cerebral artery aneurysm. The aneurysm was surgically clipped in view of the morphology of the aneurysm. Second clipping was performed four months later as there was re-growth of the neck of the aneurysm. Again re-growth of the aneurysm was noted five months after the second clipping. As further clipping of the aneurysm would be difficult, external and internal carotid arteries bypass was the treatment option but unfortunately, the by-pass operation was unsuccessful. Interestingly, angiogram performed after the bypass surgery revealed partial thrombosis and decreasing size of the aneurysm. Complete obliteration of the aneurysm was noted without further intervention one month after the failed by-pass surgery.

An intracranial aneurysm on the feeding artery of a cerebellar hemangioblastoma. Case report

A case of cerebellar hemangioblastoma with a coexistent arterial aneurysm on the feeding artery of the tumor is reported. The patient presented with an acute onset of headache, loss of consciousness, and left-sided hemiparesis due to a posterior fossa hemorrhage found adjacent to a hemangioblastoma. Four-vessel angiography revealed an aneurysm on the anterior inferior cerebellar artery (AICA), which was the main feeding vessel of the hemangioblastoma. Successful total excision of the hemangioblastoma and clipping of the AICA aneurysm achieved in a one-stage operation was demonstrated on postoperative angiography.

Intracerebral tumor-associated hemorrhage caused by overexpression of the vascular endothelial growth factor isoforms VEGF121 and VEGF165 but not VEGF189

The vascular endothelial growth factor (VEGF) has been shown to be a significant mediator of angiogenesis during a variety of normal and pathological processes, including tumor development. Human U87MG glioblastoma cells express the three VEGF isoforms: VEGF121, VEGF165, and VEGF189. Here, we have investigated whether these three isoforms have distinct roles in glioblastoma angiogenesis. Clones that overexpressed each isoform were derived and inoculated into mouse brains. Mice that received VEGF121- and VEGF165-overexpressing cells developed intracerebral hemorrhages after 60-90 hr. In contrast, mice implanted with VEGF189-overexpressing cells had only slightly larger tumors than those caused by parental cells and little evidence of hemorrhage at these early times after implantation, whereas, after longer periods of growth, enhanced angiogenicity and tumorigenicity were apparent. There was rapid blood vessel growth and breakdown around the tumors caused by cells overexpressing VEGF121 and VEGF165, whereas there was similar vascularization but no eruption in the vicinity of those tumors caused by cells overexpressing VEGF189, and none on the border of the tumors caused by the parental cells. Thus, by introducing VEGF-overexpressing glioblastoma cells into the brain, we have established a reproducible and predictable in vivo model of tumor-associated intracerebral hemorrhage caused by the enhanced expression of single molecular species. Such a model should be useful for uncovering the role of VEGF isoforms in the mechanisms of angiogenesis and for investigating intracerebral hemorrhage due to ischemic stroke or congenital malformations.