Venous-predominant parenchymal arteriovenous malformation: a rare subtype with a venous drainage pattern mimicking developmental venous anomaly

Current and Future Applications of Arterial Spin Labeling MRI in Cerebral Arteriovenous Malformations

Arterial spin labeling (ASL) has emerged as a promising noninvasive tool for the evaluation of both pediatric and adult arteriovenous malformations (AVMs). This paper reviews the advantages and challenges associated with the use of ASL in AVM assessment. An assessment of the diagnostic workup of AVMs and their variants in both adult and pediatric populations is proposed. Evaluation after treatments, whether endovascular or microsurgical, was similarly examined. ASL, with its endogenous tracer and favorable safety profile, offers functional assessment and arterial feeder identification. ASL has demonstrated strong performance in identifying feeder arteries and detecting arteriovenous shunting, although some studies report inferior performance compared with digital subtraction angiography (DSA) in delineating venous drainage. Challenges include uncertainties in sensitivity for specific AVM features. Detecting AVMs in challenging locations, such as the apical cranial convexity, is further complicated, demanding careful consideration due to the risk of underestimating total blood flow. Navigating these challenges, ASL provides a noninvasive avenue with undeniable merits, but a balanced approach considering its limitations is crucial. Larger-scale prospective studies are needed to comprehensively evaluate the diagnostic performance of ASL in AVM assessment.

An Illustrative Review of the Pathomechanisms of Symptomatic Developmental Venous Anomalies

OBJECTIVE

Symptomatic developmental venous anomalies (DVAs) are rare. Here, we illustrate the varied clinicoradiologic profiles of symptomatic DVAs and contemplate the mechanisms that render these (allegedly) benign entities symptomatic supported by a review of literature.

METHODS

Institutional databases were searched to identify cases of symptomatic DVAs. Clinical and imaging (angiographic and cross-sectional) data of 9 cases with 11 neurovascular symptoms consequent to inflow/outflow perturbations and mechanical obstruction that manifested because of the strategic topography of underlying DVAs were analyzed. A review of the existing literature on DVAs in agreement with our case series was performed on publications retrieved from the PubMed database.

RESULTS

Symptoms secondary to venous hypertension arising from flow-related perturbations were broadly divided into those arising from restricted outflow and increased inflow. Restricted outflow occurred because of collector vein stenosis (n = 2) and collector vein/DVA thrombosis (n = 3), whereas the latter pathomechanism was initiated by arterialized/transitional DVAs (n = 2). A mechanical/obstructive pathomechanism culminating in moderate supratentorial ventriculomegaly was noted in 1 case. One patient was given a diagnosis of hemorrhage associated with a cavernoma.

CONCLUSIONS

Awareness and contextualization of potential flow-related perturbations and mechanical insults that render DVAs symptomatic aid in accurate diagnosis, management, and prognostication.

Conjoined Pathways: Unraveling the Coexistence of Developmental Venous Anomaly With Arteriovenous Malformation

Developmental venous anomalies (DVAs) are intracranial vascular malformations typically characterized by their benign nature, often obviating the need for radiological follow-up. These anomalies arise from variations in the standard drainage pattern. While previously deemed congenital, there has been ongoing debate about a developmental component contributing to their etiology. They frequently coexist with other cerebral venous malformations (CVM); however, their association with arteriovenous malformations (AVM) is exceedingly rare. Such mixed malformations pose a therapeutic challenge, necessitating meticulous consideration for appropriate treatment. We present a noteworthy case involving a patient with arteriovenous malformation along with dual developmental venous anomalies, one of which served as the draining vein for the AVM.

Arterial Spin-Labeling MR Imaging for the Differential Diagnosis of Venous-Predominant AVMs and Developmental Venous Anomalies

BACKGROUND AND PURPOSE

Venous-predominant AVMs are almost identical in appearance to developmental venous anomalies on conventional MR imaging. Herein, we compared and analyzed arterial spin-labeling findings in patients with developmental venous anomalies or venous-predominant AVMs, using DSA as the criterion standard.

MATERIALS AND METHODS

We retrospectively collected patients with either DVAs or venous-predominant AVMs, each available on both DSA and arterial spin-labeling images. Arterial spin-labeling imaging was visually assessed for the presence of hyperintense signal. CBF measured at the most representative section was normalized to the contralateral gray matter. The temporal phase of developmental venous anomalies or venous-predominant AVMs was measured on DSA as a delay between the first appearance of the intracranial artery and the lesion. Correlation between the normalized CBF and the temporal phase was evaluated.

RESULTS

Analysis of 15 lesions (13 patients) resulted in categorization into 3 groups: typical venous-predominant AVMs (temporal phase, <2 seconds), intermediate group (temporal phase between 2.5 and 5 seconds), and classic developmental venous anomalies (temporal phase, >10 seconds). Arterial spin-labeling signal was markedly increased in the typical venous-predominant AVM group, while there was no discernible signal in the classic developmental venous anomaly group. In the intermediate group, however, 3 of 6 lesions showed mildly increased arterial spin-labeling signal. The normalized CBF on arterial spin-labeling and the temporal phase on DSA were moderately negatively correlated: r(13) = 0.66, P = .008.

CONCLUSIONS

Arterial spin-labeling may predict the presence and amount of arteriovenous shunting in venous-predominant AVMs, and using arterial spin-labeling enables confirmation of typical venous-predominant AVMs without DSA. However, lesions with an intermediate amount of shunting suggest a spectrum of vascular malformations ranging from purely vein-draining developmental venous anomalies to venous-predominant AVMs with overt arteriovenous shunting.

Imaging the Cerebral Veins in Pediatric Patients: Beyond Dural Venous Sinus Thrombosis

The range of intracranial venous anomalies in children differs from that in adults. As a commonly encountered highly morbid disease, sinovenous thrombosis has been discussed extensively in the literature, and the associated imaging considerations are similar in pediatric and adult patients. The authors shift the focus to less frequently discussed cerebral venous diseases in pediatric patients. First, the practical embryology pertinent to malformations, syndromes, and variants such as vein of Galen aneurysmal malformation, Sturge-Weber syndrome, and developmental venous anomalies are discussed. Second, anatomic considerations that are applicable to neuroimaging in pediatric patients with cerebral venous anomalies are reviewed. In the discussion of anatomy, special attention is given to the medullary venous system that serves the cerebral white matter, superficial cortical veins (tributaries of the dural venous sinuses), and bridging veins, which carry blood from the superficial cortical veins through the potential subdural space into the dural venous sinuses. Third, the selection of imaging modalities (US, CT and CT venography, and MRI) is addressed, and various MR venographic pulse sequences (time-of-flight, phase-contrast, and contrast-enhanced sequences) are compared. Finally, a broad variety of congenital and acquired superficial and deep venous diseases in children are reviewed, with emphasis on less frequently discussed entities involving the medullary (eg, deep medullary venous engorgement and thrombosis, periventricular hemorrhagic venous infarction due to germinal matrix hemorrhage), cortical (eg, cortical venous thrombosis), and bridging (eg, acute and chronic manifestations of injury in abusive head trauma) veins, as well as the deep veins and dural venous sinuses (eg, varix). © RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Developmental venous anomaly associated with dural arteriovenous fistula: Etiopathogenesis and hemorrhagic risk

Introduction

Developmental venous anomalies (DVAs) have traditionally been defined as non-pathological congenital lesions. Compared to isolated DVAs, the association of DVAs with arteriovenous shunts seems to have a more adverse clinical connotation. In this review, we describe the association between DVA and dAVF and discuss the hemorrhagic risk. We also advance a hypothesis about the potential de novo formation of a DVA and challenge the dogma about their "developmental" or "congenital" nature.

Methods

A systematic review of the literature on the association of DVA and dAVF was performed in accordance with the PRISMA-P (Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols) guidelines.

Results

A number of 678 papers was initially identified, but only 9 studies were included in the final qualitative analysis. Most of the patients presented with bleeding (56%), with a median GCS of 14 (range 10-15). In 56% of the cases the DVA had a supratentorial location. Supratentorial DVAs mostly drained in the superior sagittal sinus (80%), while all of infratentorial/combined DVAs drained in deep ependymal veins of the 4th ventricle. All the supratentorial dAVFs drained into the superior sagittal sinus, while the infratentorial/combined dAVFs mostly drained in the jugular bulb, Vein of Rosenthal, or transverse-sigmoid sinuses (75%). Most of the dAVFs were classified as Cognard type IIa + b (67%), while in a smaller number of cases type I (22%) and type V (11%). The dAVF was the target of treatment in each case and most patients underwent endovascular treatment (78%). The dAVF was completely occluded in 78% of cases and no periprocedural complications were reported.

Conclusion

The clinical presentation, radiological findings, and treatment outcomes of DVAs and associated dAVFs have been discussed. Despite the general opinion that DVAs are benign congenital lesions, increasing epidemiological and radiological evidence supports a potential acquired origin, and the venous system seem to play a pivotal role in their post-natal genesis and development.

Spontaneous regression of a symptomatic developmental venous anomaly with capillary stain

BACKGROUND

Developmental venous anomalies are considered benign lesions; however, they can become symptomatic. A capillary stain, which is an atypical angiographical feature of developmental venous anomalies, is reported to be relevant to symptomatic developmental venous anomalies.

CASE DESCRIPTION

A 20-year-old man with no pertinent medical history had an epileptic seizure. Magnetic resonance imaging showed severe focal oedema and gadolinium contrast enhancement in the right precentral gyrus and inferior frontal gyrus adjacent to the Sylvian fissure, indicating venous congestion; these presentations had not been observed on magnetic resonance imaging 8 months before. Digital subtraction angiography revealed a developmental venous anomaly with capillary stain. After conservative treatment, the brain oedema resolved spontaneously and contrast enhancement of the lesion reduced significantly.

CONCLUSION

We report a rare case of a symptomatic developmental venous anomaly with unique radiological characteristics and its natural and clinical evolution. Despite the presence of a capillary stain, our patient exhibited temporary exacerbations and spontaneous regression, suggesting that the capillary stain was associated with a reversible condition. This is the first report to detail the spatiotemporal changes of a developmental venous anomaly with capillary stain through imaging, suggesting that regular follow-up imaging is warranted in the management of patients with developmental venous anomalies.

Isolated hemorrhagic arterialized DVAs: revisiting symptomatic DVAs

We aim to present here a small case series of symptomatic isolated hemorrhagic arterialized developmental venous anomalies (sDVAs) with a larger goal of revisiting the classification based on patho-mechanisms plus emphasizing angiographic features coupled with CT and MRI. Typically, DVA is an incidental and silent abnormality on neuroimaging. Understanding its morphology in terms of arterialization and relationship with other entities is crucial for management. One adult and two pediatric cases presented with acute or sub-acute hemorrhage in the cerebellum or thalamus. Morphologic characterization on cross-sectional imaging and catheter angiography confirmed the integrated diagnosis of "symptomatic isolated hemorrhagic arterialized DVAs with deeper or superficial venous drainage". Conservative management was adopted in all cases. We emphasize the following classification and approach for symptomatic DVAs: (1) congestive isolated arterialized sDVAs, (2) congestive isolated resistive sDVAs, (3) coexisting sDVAs (with AVM or cavernous malformation), (4) compressive sDVAs (compressive effects), and (5) idiopathic DVAs. Like our three cases, ganglionic and infratentorial DVAs have higher propensity of hemorrhage, compressive effects, and usually harbor deeper venous drainage. Typical "caput medusae" as dominant collector vein on cross-sectional imaging is crucial to complement and even confirm the diagnosis of DVA before catheter angiography in sDVAs. Capillary stain or early opacification of DVAs is a marker of arteriovenous shunting in arterialized sDVAs. Recognition of this entity is crucial as treatment is usually conservative.

Successful Cesarean Section Deliveries in a Patient with a History of Developmental Venous Anomaly-Induced Hemorrhage

While hemorrhage can occur because of developmental venous anomalies (DVAs), there is no established opinion concerning their association with pregnancy and childbirth. In the present report, we discuss the case of a now 39-year-old woman with DVA in whom pregnancy and childbirth were successful. When she was 28, she experienced disturbance of consciousness and paralysis on the left side of the body, and brain computed tomography revealed cerebral hemorrhage coupled with subarachnoid hemorrhage. Cerebral angiography revealed a DVA with an arteriovenous shunt, with superficial drainage surrounding the hematoma. No associated cavernous hemangiomas were observed, and the patient was diagnosed with DVA-induced hemorrhage and treated via conservative therapy. Later, at the ages of 32 and 35, she gave birth via Caesarean section under general anesthesia. At the age of 37, she experienced sudden headache and nausea, following which she was again diagnosed with DVA-induced hemorrhage. Fortunately, she experienced no exacerbation of symptoms such as paralysis. However, she currently has mild, residual paralysis on the left side of the body, and she regularly walks to the hospital using a cane for follow-up examinations.

A Rare Case of Supratentorial Cavernous Angioma Associated with Arterialized Developmental Venous Anomaly

The association of cavernous malformations and developmental venous anomalies (DVA) is well known, but the presence of arterial fistulous connection with the main venous collector has been reported in the literature only once. We report the unusual case of a hemorrhagic cavernous angioma associated with DVA characterized by a fine arterial supply to the main venous collector. During surgery, after the excision of the cavernous angioma, few small arterial feeders were found entering the main channel of the venous developmental anomaly. The presence of an arterial fistulous connection with the main venous collector of a DVA may be a possible mechanism involved in a higher bleeding potential of cavernous angioma.

A rupture risk analysis of cerebral cavernous malformation associated with developmental venous anomaly using susceptibility-weighted imaging

PURPOSE

To search for the risk factors closely related to cerebral cavernous malformation associated with developmental venous anomaly (CCM-DVA) lesions rupture, laying foundations for the development of reasonable individual treatment plans for patients.

METHODS

In this retrospective study, we collected CCM-DVA patients who met the inclusion criteria in our outpatient department from 2014 to 2017, MRI scans were performed including susceptibility-weighted imaging (SWI) and contrast-enhanced imaging, characteristics and basic clinical information were collected then statistically analyzed, CCM-DVA lesions were divided into 3 types according to the location and quantitative relationship between CCM and DVA.

RESULTS

A total number of 319 adult patients were identified with 41.2±11.9 years on average, though univariate and multivariate regression analysis, ruptured presentations were more common in patients with prior hemorrhage (p=0.003), type III CCM-DVA lesions (p=0.001), lesions volume>1 cm³ (p<0.001), infratentorial lesions especially located in midbrain (p=0.019), pontine (p=0.007), medulla (p=0.015). Caplan-Meier curve shows a lower Hemorrhage-free survival rate on patients with type III CCM-DVA lesions (log-rank, p=0.0222), functional area lesions (log-rank, p<0.001), lesions volume>1 cm³ (log-rank, p<0.001), infratentorial lesions (log-rank, p=0.0002).

CONCLUSION

The classification based on the relationship between CCM and DVA may be meaningful to predict the risk of lesion rupture and CCM lesions next to DVA distal branches showed a higher risk of rupture.

Clinical and Arterial Spin Labeling Brain MRI Features of Transitional Venous Anomalies

BACKGROUND AND PURPOSE

Transitional venous anomalies (TVAs) are rare cerebrovascular lesions that resemble developmental venous anomalies (DVAs), but demonstrate early arteriovenous shunting on digital subtraction angiography (DSA) without the parenchymal nidus of arteriovenous malformations (AVMs). We investigate whether arterial spin labeling (ASL) magnetic resonance imaging (MRI) can distinguish brain TVAs from DVAs and guide their clinical management.

METHODS

We conducted a single-center retrospective review of patients with brain parenchymal DVA-like lesions with increased ASL signal on MRI. Clinical histories and follow-up information were obtained. Two readers assessed ASL signal location relative to the vascular lesion on MRI and, if available, the presence of arteriovenous shunting on DSA.

RESULTS

Thirty patients with DVA-like lesions with increased ASL signal were identified. Clinical symptoms prompted MRI evaluation in 83%. Symptoms did not localize to the venous anomaly in 90%. Ten percent presented with acute symptoms, only one of whom presented with hemorrhage. ASL signal in relation to the venous anomaly was identified in: 50% in the adjacent parenchyma, 33% in the lesion, 7% in a distal draining vein/sinus, and 10% in at least two of these sites. Follow-up DSA confirmed arteriovenous shunting in 71% of ASL-positive venous anomalies. Interrater agreement was very good (κ = .81-1.0, P < .001).

CONCLUSION

A DVA-like lesion with increased ASL signal likely represents a TVA with arteriovenous shunting. Our study indicates that these lesions are usually incidentally detected and have a lower risk of hemorrhage than AVMs. ASL-MRI may be a useful tool to identify TVAs and guide further management of patients with TVAs.

Cavernous Malformation Associated With Arterialized Developmental Venous Anomaly: A Case Report

BACKGROUND AND IMPORTANCE: Formation of cavernous malformations (CMs) has been recognized to be associated with developmental venous anomaly (DVA) by many authors. Hemodynamic stress due to venous outflow restriction could be hypothesized as a cause. On the other hand, a rare subgroup of DVA with an arterial component has been reported as likely to hemorrhage or be symptomatic. Cases of arterialized DVAs reported previously have not been associated with the presence of CM.

CLINICAL PRESENTATION: We present herein a case report of arterialized DVA in the brainstem with repeated cerebellar hemorrhage. The 49-year-old patient was treated with surgical evacuation of hematoma. A surgical specimen from the hematoma cavity demonstrated CMs on histological examination.

CONCLUSION: To the best of our knowledge, this represents the first report of CM associated with an arterialized DVA. In addition to venous congestion due to outflow obstruction, bleeding from the arterial component of the DVA might be considered as a cause of CM formation.

Tumefactive demyelination associated with developmental venous anomaly: Report of two cases

We present two cases of tumefactive demyelination (TD) occurring in close association with a developmental venous anomaly (DVA). Our purpose is to describe the association between demyelinating lesions and venous anomalies, as only one case of TD associated with a DVA has been published in the literature. Appropriate recognition of this "do not touch" lesion may avoid invasive and potentially harmful procedures such as biopsy or resection.

Contemporary Imaging of Cerebral Arteriovenous Malformations

OBJECTIVE

Brain arteriovenous malformation (AVM) rupture results in substantial morbidity and mortality. The goal of AVM treatment is eradication of the AVM, but the risk of treatment must be weighed against the risk of future hemorrhage.

CONCLUSION

Imaging plays a vital role by providing the information necessary for AVM management. Here, we discuss the background, natural history, clinical presentation, and imaging of AVMs. In addition, we explain advances in techniques for imaging AVMs.

Developmental Venous Anomaly: Benign or Not Benign

Developmental venous anomalies (DVAs), previously called venous angiomas, are the most frequently encountered cerebral vascular malformations. However, DVA is considered to be rather an extreme developmental anatomical variation of medullary veins than true malformation. DVAs are composed of dilated medullary veins converging centripetally into a large collecting venous system that drains into the superficial or deep venous system. Their etiology and mechanism are generally accepted that DVAs result from the focal arrest of the normal parenchymal vein development or occlusion of the medullary veins as a compensatory venous system. DVAs per se are benign and asymptomatic except for under certain unusual conditions. The pathomechanisms of symptomatic DVAs are divided into mechanical, flow-related causes, and idiopathic. However, in cases of DVAs associated with hemorrhage, cavernous malformations (CMs) are most often the cause rather than DVAs themselves. The coexistence of CM and DVA is common. There are some possibilities that DVA affects the formation and clinical course of CM because CM related to DVA is generally located within the drainage territory of DVA and is more aggressive than isolated CM in the literature. Brain parenchymal abnormalities surrounding DVA and cerebral varix have also been reported. These phenomena are considered to be the result of venous hypertension associated with DVAs. With the advance of diagnostic imagings, perfusion study supports this hypothesis demonstrating that some DVAs have venous congestion pattern. Although DVAs should be considered benign and clinically silent, they can have potential venous hypertension and can be vulnerable to hemodynamic changes.

Developmental venous anomalies of the brain in children -- imaging spectrum and update

Developmental venous anomalies (DVAs) are the most common vascular malformation of the brain and are commonly identified on routine imaging of the brain. They are typically considered incidental findings, usually with no clinical significance. However the increasing identification of DVAs as a result of improved imaging technology has led to recognition of their association with a variety of abnormal imaging findings and clinically important conditions. This pictorial essay explores the suspected embryological origin, associated imaging features, and proposed pathophysiological mechanisms of DVAs in the pediatric population. This paper emphasizes newer physiological imaging data, which suggest that DVA drainage has less physiological flexibility than otherwise normal venous drainage development.

Long-term treatment outcome of venous-predominant arteriovenous malformation

OBJECTIVE

Treatment strategies for venous-predominant arteriovenous malformation (vp-AVM) remain unclear due to the limited number of cases and a lack of long-term outcomes. The purpose of this study was to report the authors' experience with treatment outcomes with a review of the pertinent literature in patients with vp-AVM.

METHODS

Medical and radiological data from 1998 to 2011 were retrospectively evaluated. The degree of the arteriovenous (AV) shunt was categorized into 2 groups, a high- and low-flow AV shunt based on the angiographic findings.

RESULTS

Sixteen patients with a mean age of 45.3 years (range 16-78 years) and a mean follow-up of 79.9 months (range 25-264 months) were examined. Symptomatic lesions were noted in 13 patients: intracranial hemorrhage (ICH) in 9, seizure in 1, and headache in 3. A high-flow shunt was observed on angiography in 13 patients. Among these 13 patients, 12 patients were symptomatic. Nine patients presenting with ICH underwent hematoma removal with additional Gamma Knife surgery (GKS; n = 4), GKS only (n = 2), or conservative treatment (n = 3). The 3 asymptomatic patients received conservative treatment, and 1 rebleeding episode was observed. Seven of 8 patients who underwent GKS as an initial or secondary treatment modality experienced a marked reduction in the AV shunt on follow-up angiography, but complete obliteration was not observed.

CONCLUSIONS

Poor lesion localization makes a vp-AVM challenging to treat. Symptomatic patients with a high-flow shunt are supposedly best treated with GKS, despite the fact that only 87.5% of the vp-AVMs treated this way showed a reduction in the malformation volume, and none were cured.

Multimodal Imaging Follow-up of a Thrombosed Developmental Venous Anomaly: CT, CT Angiography and Digital Subtraction Angiography

We report a rare case of thrombosed developmental venous anomaly (DVA) in a 31-year old male with hemorrhagic cerebral venous infarction at the initial clinical presentation. In this case, sequential CT, CT angiography and digital subtraction angiography demonstrated thrombotic obstruction of the venous drainage from DVA, its progressive recanalization and temporal evolution of the affected brain parenchyma. The relevant previous literatures were reviewed and summarized.

Atypical developmental venous anomaly associated with single arteriovenous fistula and intracerebral hemorrhage: a case demonstrated by superselective angiography

We present a case of developmental venous anomaly associated with arteriovenous fistula supplied by a single arterial feeder adjacent to a large acute intracerebral hemorrhage. The arteriovenous fistula was successfully obliterated by superselective embolization while completely preserving the developmental venous anomaly. Two similar cases, including superselective angiographic findings, have been reported in the literature; however, we describe herein superselective angiographic findings in more detail and demonstrate the arteriovenous shunt more clearly than the previous reports. In addition, a literature review was performed to discuss the association of a developmental venous anomaly with vascular lesions.

Clinico-radiological outcomes following gamma knife radiosurgery for pediatric arteriovenous malformations

PURPOSE

The aim of this study was to evaluate clinico-radiological outcomes following gamma knife radiosurgery (GKS) for pediatric arteriovenous malformations (AVMs).

METHODS

The present series included 39 children (3-17 years of age) who underwent GKS for cerebral AVMs between January 2002 and February 2008. Twenty-five patients presented with hemorrhages. The median AVM volume was 1.5 cm³, and the median marginal dose was 20 Gy. All patients continued to have follow-up for more than 24 months with serial magnetic resonance images (MRIs)/angiograms. Current school performance has been evaluated using a telephone survey answered by the patients' parents.

RESULTS

Follow-up angiograms, available in 34 patients, confirmed complete obliteration in 16 patients. Serial MRIs indicated obliteration of the nidus in one of five patients without angiography. The diffuse nidus structure and low marginal dose were significantly associated with incomplete obliteration. Twelve patients underwent a second GKS, and subsequent angiographies, available in six patients, demonstrated complete obliteration in two of them. Complications included new-onset seizures (n = 1), apraxia (n = 1), and temporal horn entrapment requiring a shunt operation (n = 1). School performance declined in 14 out of 32 patients. Both the AVM volume and modified AVM score were found to be reliable predictors of school performance.

CONCLUSIONS

The results of the present study substantiate the diffuse and other atypical features of pediatric AVMs as major determinants of treatment failure following GKS. Considering the apparent declination of school performance, future prospective studies would be required to investigate the possible late-effects of GKS on neuropsychological function.

Developmental Venous Anomalies (DVA): What Are They Really?

Purpose: The aim of this paper is to analyse the pathophysiology of 3 DVA cases from our institution, review the literature and propose a classification of these lesions. Materials & Methods: The pathophysiology of DVAs were analysed with CT perfusion (CTP), 4 dimensional dynamic computed tomography angiography (4D CTA) and catheter digital subtraction angiography. Results: Symptomatic DVAs may be caused by associated lesions and compression of neural structures by the DVAs. The imbalance between the inflow and outflow of these lesions, including venous ischaemia, has also been postulated as a cause. Our analysis showed that increased cerebral blood flow (CBF) and cerebral blood volume (CBV) and decreased mean transit time (MTT) and time to peak (TTP) were found in DVAs with micro arteriovenous shunting. DVAs without shunting had raised MTT and TTP instead. Conclusion: We postulate that the arteriovenous shunting resulted in arterial steal and chronic hypoxia which could be a pathophysiological mechanism for symptomatic DVAs. CTP and 4D CTA are effective non invasive tools to study DVAs. A classification is proposed.

Cerebral developmental venous anomalies

INTRODUCTION

Cerebral developmental venous anomalies (DVAs) are the most frequently encountered cerebral vascular malformation. As such, they are often observed incidentally during routine CT and MRI studies. Yet, what DVAs represent from a clinical perspective is frequently not common knowledge and DVAs, therefore, still generate uncertainty and concern amongst physicians. This article reviews our current understanding of developmental venous anomalies.

RESULTS

In the majority of cases, DVAs follow a benign clinical course. On rare occasions, DVAs become symptomatic generally due to an underlying associated vascular malformation such as cavernous malformations or thrombosis of the collecting vein. Rare forms of DVAs include arterialized DVAs and DVAs involved in the drainage of sinus pericranii, which warrant additional investigation by digital subtraction angiography. Cerebral abnormalities such as atrophy, white matter lesions and calcifications within the drainage territory of asymptomatic DVAs, are often identified on CT or MR imaging studies and likely represent secondary changes due to venous hypertension. There is increasing evidence that DVAs have a propensity for developing venous hypertension, which is thought to be the cause of associated cavernous malformations and parenchymal abnormalities.

CONCLUSIONS

DVAs represent variations of the normal cerebral venous angioarchitecture and by enlargement follow an uneventful clinical course. Complications can, however, occur and their management requires a thorough understanding of the nature of DVAs, including their frequent coexistence with other types of vascular malformation, and the existence of more complex but rare forms of presentation, such as the arterialized DVAs.

The putative role of the venous system in the genesis of vascular malformations

Recent clinical and experimental evidence has challenged the traditional concept of the venous system as a “passive” element in the genesis and evolution of intracranial vascular malformations. The authors review the clinical and experimental evidence linking the venous system and its anomalies to the genesis of various intracranial vascular malformations, including dural arteriovenous fistulas, cavernous malformations, parenchymal arteriovenous malformations, and capillary telangiectasia. They also describe the potential significance of different associations of these vascular anomalies.