Reporting terminology for brain arteriovenous malformation clinical and radiographic features for use in clinical trials

Common variants on 9p21.3 are associated with brain arteriovenous malformations with accompanying arterial aneurysms

OBJECTIVE

To investigate whether previously reported 9p21.3 single nucleotide polymorphisms (SNPs) are associated with risk of brain arteriovenous malformations (BAVM), which often have accompanying arterial aneurysms. Common variants in the 9p21.3 locus have been reported to be associated with multiple cardiovascular phenotypes, including coronary artery disease and intracranial aneurysms (rs10757278 and rs1333040).

METHODS

We used data from 338 BAVM cases participating in the University of California, San Francisco (UCSF)-Kaiser Brain AVM Study Project and 504 healthy controls to evaluate genotypes for seven common SNPs (minor allele frequency>0.05) that were imputed using 1000 Genomes Phase 1 European data (R(2)>0.87). Association with BAVM was tested using logistic regression adjusting for age, sex and the top three principal components of ancestry. Subgroup analysis included 205 BAVM cases with aneurysm data: 74 BAVM with aneurysm versus 504 controls and 131 BAVM without aneurysm versus 504 controls.

RESULTS

We observed suggestive association with BAVM and rs10757278-G (OR=1.23, 95% CI 0.99 to 1.53, p=0.064) and rs1333040-T (OR=1.27, 95% CI 1.01 to 1.58, p=0.04). For rs10757278-G, the association was stronger in BAVM cases with aneurysm (OR=1.52, 95% CI 1.03 to 2.22, p=0.032) than in BAVM without aneurysm (OR=0.98, 95% CI 0.72 to 1.34, p=0.91). Similar patterns of effects were observed for rs1333040 and for other SNPs in linkage disequilibrium (r(2)>0.8) with rs10757278.

CONCLUSIONS

Common 9p21.3 variants showed similar effect sizes for association with BAVM as previously reported for aneurysmal disease. The association with BAVM appears to be explained by known associations with aneurysms, suggesting that BAVM-associated aneurysms share similar vascular pathology mechanisms with other aneurysm types.

Multimodal angiographic assessment of cerebral arteriovenous malformations: a pilot study

PURPOSE

We describe our protocol of three-dimensional (3D) Roadmap intracranial navigation and image fusion for analysis of the angioarchitecture and endovascular treatment of brain arteriovenous malformations (AVMs).

METHODS

We performed superselective catheterization of brain AVMs feeders under 3D-Roadmap navigation. Angiograms of each catheterized artery on two registered orthogonal views were transferred to the imaging workstations, and dedicated postprocessing imaging software allowed automated multiple overlays of the arterial supply of the AVM superselective acquisitions on the global angiogram in angiographic or 3D views and on coregistered MRI datasets.

RESULTS

11 untreated brain AVMs (4 with hemorrhagic presentation) were explored. The superselective acquisitions were performed under 3D-Roadmap navigation in 74 arteries, for a total of 79 targeted arteries. Imaging analysis was available at table side or postoperatively for discussion of the therapeutic strategy. No complications occurred during superselective catheterization. The accuracy of the coregistration of angiogram and MRI was submillimetric after automated mutual information coregistration, with manual re-registration by the physicians.

CONCLUSIONS

Superselective angiograms acquired under 3D-Roadmap navigation can be postprocessed with multiple overlays. The fluoroscopic navigation under 3D-Roadmapping and the coregistration of 3D rotational angiography, selective angiography, and 3D MR datasets appears reliable with millimeter accuracy, and could be implemented in the critical brain AVM embolization setting to allow refined analysis of AVM angioarchitecture.

Predicting visual semantic descriptive terms from radiological image data: preliminary results with liver lesions in CT

We describe a framework to model visual semantics of liver lesions in CT images in order to predict the visual semantic terms (VST) reported by radiologists in describing these lesions. Computational models of VST are learned from image data using linear combinations of high-order steerable Riesz wavelets and support vector machines (SVM). In a first step, these models are used to predict the presence of each semantic term that describes liver lesions. In a second step, the distances between all VST models are calculated to establish a nonhierarchical computationally-derived ontology of VST containing inter-term synonymy and complementarity. A preliminary evaluation of the proposed framework was carried out using 74 liver lesions annotated with a set of 18 VSTs from the RadLex ontology. A leave-one-patient-out cross-validation resulted in an average area under the ROC curve of 0.853 for predicting the presence of each VST. The proposed framework is expected to foster human-computer synergies for the interpretation of radiological images while using rotation-covariant computational models of VSTs to 1) quantify their local likelihood and 2) explicitly link them with pixel-based image content in the context of a given imaging domain.

Untreated brain arteriovenous malformation: patient-level meta-analysis of hemorrhage predictors

OBJECTIVE

To identify risk factors for intracranial hemorrhage in the natural history course of brain arteriovenous malformations (AVMs) using individual patient data meta-analysis of 4 existing cohorts.

METHODS

We harmonized data from Kaiser Permanente of Northern California (n = 856), University of California San Francisco (n = 787), Columbia University (n = 672), and the Scottish Intracranial Vascular Malformation Study (n = 210). We censored patients at first treatment, death, last visit, or 10-year follow-up, and performed stratified Cox regression analysis of time-to-hemorrhage after evaluating hemorrhagic presentation, sex, age at diagnosis, deep venous drainage, and AVM size as predictors. Multiple imputation was performed to assess impact of missing data.

RESULTS

A total of 141 hemorrhage events occurred during 6,074 patient-years of follow-up (annual rate of 2.3%, 95% confidence interval [CI] 2.0%-2.7%), higher for ruptured (4.8%, 3.9%-5.9%) than unruptured (1.3%, 1.0%-1.7%) AVMs at presentation. Hemorrhagic presentation (hazard ratio 3.86, 95% CI 2.42-6.14) and increasing age (1.34 per decade, 1.17-1.53) independently predicted hemorrhage and remained significant predictors in the imputed dataset. Female sex (1.49, 95% CI 0.96-2.30) and exclusively deep venous drainage (1.60, 0.95-2.68, p = 0.02 in imputed dataset) may be additional predictors. AVM size was not associated with intracerebral hemorrhage in multivariable models (p > 0.5).

CONCLUSION

This large, individual patient data meta-analysis identified hemorrhagic presentation and increasing age as independent predictors of hemorrhage during follow-up. Additional AVM cohort data may further improve precision of estimates, identify new risk factors, and allow validation of prediction models.

Influence of patient age on angioarchitecture of brain arteriovenous malformations

BACKGROUND AND PURPOSE

The imaging characteristics and modes of presentation of brain AVMs may vary with patient age. Our aim was to determine whether clinical and angioarchitectural features of brain AVMs differ between children and adults.

MATERIALS AND METHODS

A prospectively collected institutional data base of all patients diagnosed with brain AVMs since 2001 was queried. Demographic, clinical, and angioarchitecture information was summarized and analyzed with univariable and multivariable models.

RESULTS

Results often differed when age was treated as a continuous variable as opposed to dividing subjects into children (18 years or younger; n = 203) versus adults (older than 18 years; n = 630). Children were more likely to present with AVM hemorrhage than adults (59% versus 41%, P < .001). Although AVMs with a larger nidus presented at younger ages (mean of 26.8 years for >6 cm compared with 37.1 years for <3 cm), this feature was not significantly different between children and adults (P = .069). Exclusively deep venous drainage was more common in younger subjects when age was treated continuously (P = .04) or dichotomized (P < .001). Venous ectasia was more common with increasing age (mean, 39.4 years with ectasia compared with 31.1 years without ectasia) and when adults were compared with children (52% versus 35%, P < .001). Patients with feeding artery aneurysms presented at a later average age (44.1 years) than those without such aneurysms (31.6 years); this observation persisted when comparing children with adults (13% versus 29%, P < .001).

CONCLUSIONS

Although children with brain AVMs were more likely to come to clinical attention due to hemorrhage than adults, venous ectasia and feeding artery aneurysms were under-represented in children, suggesting that these particular high-risk features take time to develop.

Brain arteriovenous malformations and seizures: an Italian study

OBJECTIVE

To evaluate seizures as first clinical manifestation of brain arteriovenous malformations (AVMs), in relation to angioarchitectural features of these vascular anomalies.

METHODS

We performed a prospective observational study, collecting records of patients with AVMs consecutively admitted to the Neurological and Neurosurgery Units of Perugia University and to the Neurosurgery Unit of Terni Hospital, during a 10-year period (1 January 2002 to 1 June 2012). Two groups of patients, with or without seizures as AVM first presentation, were analysed to identify differences in demographic and angiographic features. A multivariate logistic regression model was also developed.

RESULTS

We examined 101 patients with AVMs, 55 male and 46 female. Seizures were the initial clinical manifestation in 31 (30.7%) patients. We found a significant difference (p<0.05) between two groups of patients, with or without seizures as AVM first presentation concerning location, side, topography and venous drainage. A multivariate logistic regression model showed that clinical presentation with seizures was correlated with a location in the temporal and frontal lobes, and with a superficial topography. The strongest association (OR 3.48; 95% CI 1.77 to 6.85) was observed between seizures and AVM location in the temporal lobe.

CONCLUSIONS

Vascular remodelling and haemodynamic changes of AVMs might create conditions for epileptogenesis. However, here we show that malformations with specific angiographic characteristics are more likely to be associated with seizures as first clinical presentation. Location is the most important feature related to epilepsy and in particular the temporal lobe might play a crucial role in the occurrence of seizure.

Medical management with or without interventional therapy for unruptured brain arteriovenous malformations (ARUBA): a multicentre, non-blinded, randomised trial

BACKGROUND

The clinical benefit of preventive eradication of unruptured brain arteriovenous malformations remains uncertain. A Randomised trial of Unruptured Brain Arteriovenous malformations (ARUBA) aims to compare the risk of death and symptomatic stroke in patients with an unruptured brain arteriovenous malformation who are allocated to either medical management alone or medical management with interventional therapy.

METHODS

Adult patients (≥18 years) with an unruptured brain arteriovenous malformation were enrolled into this trial at 39 clinical sites in nine countries. Patients were randomised (by web-based system, in a 1:1 ratio, with random permuted block design [block size 2, 4, or 6], stratified by clinical site) to medical management with interventional therapy (ie, neurosurgery, embolisation, or stereotactic radiotherapy, alone or in combination) or medical management alone (ie, pharmacological therapy for neurological symptoms as needed). Patients, clinicians, and investigators are aware of treatment assignment. The primary outcome is time to the composite endpoint of death or symptomatic stroke; the primary analysis is by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00389181.

FINDINGS

Randomisation was started on April 4, 2007, and was stopped on April 15, 2013, when a data and safety monitoring board appointed by the National Institute of Neurological Disorders and Stroke of the National Institutes of Health recommended halting randomisation because of superiority of the medical management group (log-rank Z statistic of 4·10, exceeding the prespecified stopping boundary value of 2·87). At this point, outcome data were available for 223 patients (mean follow-up 33·3 months [SD 19·7]), 114 assigned to interventional therapy and 109 to medical management. The primary endpoint had been reached by 11 (10·1%) patients in the medical management group compared with 35 (30·7%) in the interventional therapy group. The risk of death or stroke was significantly lower in the medical management group than in the interventional therapy group (hazard ratio 0·27, 95% CI 0·14-0·54). No harms were identified, other than a higher number of strokes (45 vs 12, p<0·0001) and neurological deficits unrelated to stroke (14 vs 1, p=0·0008) in patients allocated to interventional therapy compared with medical management.

INTERPRETATION

The ARUBA trial showed that medical management alone is superior to medical management with interventional therapy for the prevention of death or stroke in patients with unruptured brain arteriovenous malformations followed up for 33 months. The trial is continuing its observational phase to establish whether the disparities will persist over an additional 5 years of follow-up.

FUNDING

National Institutes of Health, National Institute of Neurological Disorders and Stroke.

Gene expression profiling of blood in brain arteriovenous malformation patients

Brain arteriovenous malformations (BAVMs) are an important cause of intracranial hemorrhage (ICH) in young adults. Gene expression profiling of blood has led to the identification of stroke biomarkers, and may help identify BAVM biomarkers and illuminate BAVM pathogenesis. It is unknown whether blood gene expression profiles differ between 1) BAVM patients and healthy controls, or 2) unruptured and ruptured BAVM patients at presentation. We characterized blood transcriptional profiles in 60 subjects (20 unruptured BAVM, 20 ruptured BAVM, and 20 healthy controls) using Affymetrix whole genome expression arrays. Expression differences between groups were tested by ANOVA, adjusting for potential confounders. Genes with absolute fold change ≥ 1.2 (false discovery rate corrected p ≤ 0.1) were selected as differentially expressed and evaluated for over-representation in KEGG biological pathways (p ≤ 0.05). Twenty-nine genes were differentially expressed between unruptured BAVM patients and controls, including 13 which may be predictive of BAVM. Patients with ruptured BAVM compared to unruptured BAVM differed in expression of 1490 genes, with over-representation of genes in 8 pathways including MAPK, VEGF, Wnt signaling and several inflammatory pathways. These results suggest clues to the pathogenesis of BAVM and/or BAVM rupture and point to potential biomarkers or new treatment targets.

A practical grading scale for predicting outcome after radiosurgery for arteriovenous malformations: analysis of 1012 treated patients

Object

The authors performed a study to review outcomes following Gamma Knife radiosurgery for cerebral arteriovenous malformations (AVMs) and to create a practical scale to predict long-term outcome.

Methods

Outcomes were reviewed in 1012 patients who were followed up for more than 2 years. Favorable outcome was defined as AVM obliteration and no posttreatment hemorrhage or permanent, symptomatic, radiation-induced complication. Preradiosurgery patient and AVM characteristics predictive of outcome in multivariate analysis were weighted according to their odds ratios to create the Virginia Radiosurgery AVM Scale.

Results

The mean follow-up time was 8 years (range 2–20 years). Arteriovenous malformation obliteration occurred in 69% of patients. Postradiosurgery hemorrhage occurred in 88 patients, for a yearly incidence of 1.14%. Radiation-induced changes occurred in 387 patients (38.2%), symptoms in 100 (9.9%), and permanent deficits in 21 (2.1%). Favorable outcome was achieved in 649 patients (64.1%). The Virginia Radiosurgery AVM Scale was created such that patients were assigned 1 point each for having an AVM volume of 2–4 cm3, eloquent AVM location, or a history of hemorrhage, and 2 points for having an AVM volume greater than 4 cm3. Eighty percent of patients who had a score of 0–1 points had a favorable outcome, as did 70% who had a score of 2 points and 45% who had a score of 3–4 points. The Virginia Radiosurgery AVM Scale was still predictive of outcome after controlling for predictive Gamma Knife radiosurgery treatment parameters, including peripheral dose and number of isocenters, in a multivariate analysis. The Spetzler-Martin grading scale and the Radiosurgery-Based Grading Scale predicted favorable outcome, but the Virginia Radiosurgery AVM Scale provided the best assessment.

Conclusions

Gamma Knife radiosurgery can be used to achieve long-term AVM obliteration and neurological preservation in a predictable fashion based on patient and AVM characteristics.

Angioarchitecture determines obliteration rate after radiosurgery in brain arteriovenous malformations

BACKGROUND

Radiosurgery as a potential treatment modality for brain arteriovenous malformations (AVM) has 60% to 90% obliteration rates.

OBJECTIVE

To test whether AVM angioarchitecture determines obliteration rate after radiosurgery.

METHODS

This study was a retrospective analysis of 139 patients with AVM who underwent radiosurgery. Multiple angioarchitectural characteristics were reviewed on conventional angiogram on the day of radiosurgery: enlargement of feeding arteries, flow-related or intranidal aneurysms, perinidal angiogenesis, arteriovenous transit time, nidus type, venous ectasia, focal pouches, venous rerouting, and presence of a pseudophlebitic pattern. The radiation plan was reviewed for nidus volume and eloquence of AVM location. A chart review was performed to determine clinical presentation and previous treatment. Outcome was dichotomized into complete/incomplete obliteration, and various statistics were performed, examining whether outcome status was associated with the investigated factors.

RESULTS

Marginal dose ranged from 15 to 25 Gy (mean, 18.8 Gy), with lower doses prescribed in eloquent locations. Sizes of AVMs ranged from 0.08 to 21 cm (mean, 3.78 ± 4.19 cm). Complete AVM obliteration was achieved in 92 patients (66%) and was related to these independent factors: noneloquent location (odds ratio [OR], 3.20), size (OR, 0.88), low flow (OR, 3.47), no or mild arterial enlargement (OR, 3.32), and absence of perinidal angiogenesis (OR, 2.61). Concerning the 3 last angioarchitectural characteristics, if no or only a single factor was present in an individual patient (n = 92 patients), obliteration was observed in 74 (80%); if 2 or 3 factors were present (n = 47), obliteration was observed in 18 patients (38%; OR, 6.62).

CONCLUSION

Angioarchitectural factors that indicate high flow are associated with a lower rate of AVM obliteration after radiosurgery.

The failure of preoperative ethylene-vinyl alcohol copolymer embolization to improve outcomes in arteriovenous malformation management: case series

OBJECT

Ethylene-vinyl alcohol copolymer embolization is increasingly used preoperatively in the resection of brain arteriovenous malformations (AVMs). However, the case for embolization improving the outcome of resection has not been evaluated. In this paper the authors set out to compare outcomes after surgery for brain AVMs in 2 consecutive periods of practice. In the first period, selective embolization was used without the use of ethylene-vinyl alcohol copolymer. In the second period, selective embolization with ethylene-vinyl alcohol copolymer was performed.

METHODS

A consecutive case series (prospectively collected data) was retrospectively analyzed. Adverse outcomes were considered to be an outcome modified Rankin Scale score greater than 2 due to embolization or surgery.

RESULTS

A total of 538 surgical cases were included. The percentages of adverse outcomes were as follows: 0.34% for Spetzler-Martin AVMs less than Grade III (1 of 297 cases); 5.23% (95% CI 2.64%-9.78%) for Grade III AVMs (9 of 172 cases); and 17% (95% CI 10%-28%) for AVMs greater than Grade III (12 of 69 cases). There was no improvement in outcomes from the first period to the second period. The adverse outcome for Grade III brain AVMs in the first period was 5.2% (7 of 135 cases) and in the second period (after ethylene-vinyl alcohol copolymer was introduced) it was 5.4% (2 of 37 cases). For AVMs greater than Grade III, the adverse outcome was 12% (6 of 49 cases) in the first period and 30% (6 of 20 cases) in the second period.

CONCLUSIONS

Outcomes for brain AVM surgery were not improved by ethylene-vinyl alcohol copolymer embolization. Preoperative embolization of high-grade AVMs with an ethylene-vinyl alcohol copolymer did not prevent those hemorrhagic complications which embolization is hypothesized to prevent based on theoretical speculations but not demonstrated in practice.

Relevance of bleeding pattern on clinical appearance and outcome in patients with hemorrhagic brain arteriovenous malformations

Although several descriptions of the angioarchitectural features of brain arteriovenous malformations (AVMs) associated with higher hemorrhagic risk have been reported, the prognostic value of the different bleeding patterns still needs to be elucidated. This study evaluated the influence on clinical appearance and outcome of the parenchymal and non-parenchymal (subarachnoid hemorrhage-SAH-and intraventricular hemorrhage-IVH) bleedings associated with ruptured AVMs. Clinical records and neuroradiological examinations of 30 patients with hemorrhagic AVMs were reviewed in order to identify their angioarchitectural features and the associated bleeding pattern. These data along with demographic characteristics and treatment modality were dichotomized and their relationship with clinical status at admission and follow-up was tested. IVH as well as parenchymal hematomas larger than 20 cm(3) appeared associated with a severe clinical status at admission, whereas SAH involving basal cisterns was significantly associated with unfavorable outcome. Age, sex and angioarchitectural features did not show significant association with the severity of the prognosis. However, none of these bleeding patterns appeared as an independent risk factor of poor outcome at multivariate analysis. In conclusion, our data emphasized the possibility that non-parenchymal bleeding may worsen the outcome of patients with hemorrhagic AVMs.

The rs9509 polymorphism of MMP-9 is associated with risk of hemorrhage in brain arteriovenous malformations

We examined whether single nucleotide polymorphisms (SNP) of the matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteinase 4 (TIMP-4) genes are associated with risk of intracranial hemorrhage (ICH) among patients with brain arteriovenous malformation (BAVM). For 311 Chinese patients with BAVM, we performed genotyping analysis for 11 selected SNP of MMP-9 and TIMP-4 using the MassARRAY genotyping system (Sequenom, San Diego, CA, USA). Associations between each genotype and risk of hemorrhage were evaluated using logistic regression analysis. Multivariate logistic regression analysis revealed that MMP-9_rs9509 was significantly associated with ICH among patients with BAVM with adjustments for BAVM size, venous drainage type, age and sex (adjusted odds ratio [OR]=0.19; 95% confidence interval [CI]=0.05-0.66; p=0.009 for CC compared with TT genotype). However, the association was not significant (p=0.072) after Bonferroni correction and was not significant (p=0.064) in the univariate model. The TIMP-4_rs3755724 polymorphism did not have a statistically significant effect in the multivariate model (adjusted OR=0.57; 95% CI=0.32-1.01; p=0.055 for CT compared with TT genotype). The global score test did not reveal any statistically significant differences in haplotype frequency distributions for these two genes. Our findings suggest that the MMP-9_rs9509 polymorphism may be associated with ICH in patients with BAVM.

G Protein-Coupled Receptor 124 (GPR124) Gene Polymorphisms and Risk of Brain Arteriovenous Malformation

Abnormal endothelial proliferation and angiogenesis may contribute to brain arteriovenous malformation (BAVM) formation. G protein-coupled receptor 124 (GPR124) mediates embryonic CNS angiogenesis; thus we investigated the association of single nucleotide polymorphisms (SNPs) and haplotypes in GPR124 with risk of BAVM. Ten tagging SNPs spanning 39 kb of GPR124 were genotyped in 195 Caucasian BAVM patients and 243 Caucasian controls. SNP and haplotype association with risk of BAVM was screened using χ(2) analysis. Associated variants were further evaluated using multivariable logistic regression, adjusting for age and sex. The minor alleles of 3 GPR124 SNPs adjacent to exon 2 and localized to a 16 kb region of high linkage disequilibrium were associated with reduced risk of BAVM (rs7015566 A, P=0.001; rs7823249 T, P=0.014; rs12676965 C, P=0.007). SNP rs7015566 (intron 1) remained associated after permutation testing (additive model P=0.033). Haplotype analysis revealed a significant overall association (χ(2)=12.55, 4 df, P=0.014); 2 haplotypes (ATCC, P=0.006 and GGCT, P=0.008) were associated with risk of BAVM. We genotyped a known synonymous SNP (rs16887051) in exon 2, however genotype frequency did not differ between cases and controls. Sequencing of conserved GPR124 regions revealed a novel indel polymorphism in intron 2. Immunohistochemistry confirmed GPR124 expression in the endothelium with no qualitative difference in expression between BAVM cases and controls. SNP rs7015566 mapping to intron 1 of GPR124 was associated with BAVM susceptibility among Caucasians. Future work is focused on investigating this gene region.

Pediatric intracranial nongalenic pial arteriovenous fistulas: clinical features, angioarchitecture, and outcomes

BACKGROUND AND PURPOSE

NGAVFs are rare vascular malformations usually presenting in infancy or childhood. We sought to identify clinical and angiographic predictors of clinical outcome for these lesions.

MATERIALS AND METHODS

Retrospective review of a neurointerventional data base identified 386 pediatric patients with intracranial AVFs and AVMs, from which a cohort of 25 patients with NGAVF were selected for medical record and imaging analysis.

RESULTS

NGAVFs constituted 7.3% of pediatric intracranial vascular lesions with a nondural arteriovenous shunt. Seven of 8 patients who presented in the first month of life had CHF and harbored large, complex fistulas with multiple sites of arteriovenous shunting. Single-hole fistulas predominated later in childhood and more frequently presented with seizures, hemorrhage, or focal neurologic deficits. More treatment procedures were performed in subjects presenting at ≤ 2 years of age compared with older children (median = 3 versus 2, P = .041), and in those harboring a multi-hole fistula versus those with a single-hole fistula (median = 3 versus 2, P = .003). Eighteen patients (72%) had complete posttreatment elimination of NGAVF shunting. Compared with patients presenting at >2 years of age, patients presenting in the first 2 years of life were more likely to have a multi-hole fistula (100% versus 25%, P = .0001) and to have a poor clinical outcome (54% versus 0%, P = .0052), defined as a pediatric mRS of ≥ 3.

CONCLUSIONS

The morbidity of NGAVF appears higher than previously reported despite a somewhat higher rate of angiographic cure. Poor clinical outcome occurred primarily in patients with multi-hole NGAVFs presenting at ≤ 2 years of age.

Postradiosurgery Hemorrhage Rates of Arteriovenous Malformations of the Brain

Background and Purpose—

The long-term benefit of radiosurgery of brain arteriovenous malformations (AVM), especially nonhemorrhagic cases, is controversial. We calculated hemorrhage rates pre- and posttreatment and analyzed the risk factors for bleeding based on cases followed at our site.

Methods—

One hundred eight patients, age 36±17 years, 56 men. The mean follow-up was 65±44 months (median, 54; interquartile range, 33–94). Most AVMs were small (74.1% <3 cm in diameter); 48.1% were located in an eloquent area, 27.8% had deep drainage, and 39.8% presented with hemorrhage.

Results—

The annual hemorrhage rate for any undiagnosed AVM was 1.2%, and 3.3% for AVMs with hemorrhagic presentation. Older patients, cortical or subcortical AVMs, and cases with multiple draining veins were less likely to present with bleeding. During the first 36 months postradiosurgery, hemorrhagic AVMs had a rebleeding rate of 2.1%, and a rate of 1.1% from 3 years onwards. Nonhemorrhagic AVMs had a hemorrhage rate of 1.4% during the first 3 years and 0.3% afterward. Arterial hypertension and nidus volume were independent predictors of bleeding after treatment. Mean nidus obliteration time was 37±18 months (median, 32; interquartile range, 25–40), with hemorrhage rate of 1.3% before and 0.6% after obliteration, and 1.9% for AVMs that were not closed at the end of follow-up.

Conclusions—

Both hemorrhagic and nonhemorrhagic AVMs benefit from radiosurgical therapy, with gradual decrease in their bleeding rates over the years. Albeit small, the risk of hemorrhage persists during the entirety of follow-up, being higher for cases with hemorrhagic presentation and nonobliterated AVM.

Nidal embolization of brain arteriovenous malformations: rates of cure, partial embolization, and clinical outcome

OBJECT

Nidal embolization of brain arteriovenous malformations (bAVMs) has become an increasingly important component of bAVM treatment. However, controversy exists as to the relative efficacy and safety of single-stage versus multistage approaches to bAVM embolization, with recent literature favoring multistage strategies. The authors present a series of consecutive bAVMs embolized at their institution, demonstrating the safety and efficacy of a predominantly single-stage embolization strategy. The safety and efficacy of embolization are reported in the context of predetermined treatment strategies to provide more generalizable insight into treatment outcome.

METHODS

One hundred thirty consecutive patients with 131 bAVMs underwent endovascular embolization at a single center. Diagnostic angiography with superselective microcatheterizations was performed in all patients. Postembolization angiograms were reviewed by 3 neuroradiologists for degree of occlusion and angiographic evidence of procedural complications. Patients were divided into cohorts based on the prospectively determined treatment strategy, which included the following: global devascularization of the bAVM (Devasc); targeting of a focal angioarchitectural weakness (Target), typically as an adjunct to surgery or Gamma Knife treatment; and primary occlusion of the bAVM by embolization alone (Occlude). Safety and efficacy were evaluated in the context of these treatment groups.

RESULTS

The 131 bAVMs were treated over an average of 1.28 embolization sessions per bAVM; 105 bAVMs (80%) were treated in a single stage. The average percentage devascularization in the Devasc arm was 85.3%, which was statistically significantly greater than the 72% aggregate devascularization reported in 8 modern N-butyl cyanoacrylate and Onyx papers based on 1-sample Wilcoxon rank-sum testing (p<0.001). Focal angioarchitectural weaknesses were successfully embolized for all 24 bAVMs in the Target group, directly with the embolic agent in 23 bAVMs and indirectly in 1 bAVM with a venous aneurysm/pseudoaneurysm by reducing arterial inflow and inducing venous thrombosis. Lesions in all patients in the Occlude arm were 100% occluded with embolization alone. Overall, the bAVMs in the Occlude arm were significantly smaller and required embolization of fewer pedicles than those in the Devasc group. One patient (0.8%) experienced significant morbidity following embolization, and 1 patient in the cohort died (0.8%).

CONCLUSIONS

This research communicates the authors' experience in developing a largely single-stage strategy for embolization of bAVMs. The results suggest that an aggressive, single-stage embolization may be implemented with a margin of safety and effectiveness similar to the multistage approaches more commonly reported in the literature. This work additionally introduces the importance of prospective assignment to a treatment strategy in assessing procedural outcome in bAVM embolization, thereby improving generalizability of the results and allowing for more rigorous interpretation of efficacy and safety.

Silent intralesional microhemorrhage as a risk factor for brain arteriovenous malformation rupture

BACKGROUND AND PURPOSE

We investigated whether brain arteriovenous malformation silent intralesional microhemorrhage, that is, asymptomatic bleeding in the nidal compartment, might serve as a marker for increased risk of symptomatic intracranial hemorrhage (ICH). We evaluated 2 markers to assess the occurrence of silent intralesional microhemorrhage: neuroradiological assessment of evidence of old hemorrhage-imaging evidence of bleeding before the outcome events-and hemosiderin positivity in hematoxylin and eosin-stained paraffin block sections.

METHODS

We identified cases from our brain arteriovenous malformation database with recorded neuroradiological data or available surgical paraffin blocks. Using 2 end points, index ICH or new ICH after diagnosis (censored at treatment, loss to follow-up, or death), we performed logistic or Cox regression to assess evidence of old hemorrhage and hemosiderin positivity adjusting for age, sex, deep-only venous drainage, maximal brain arteriovenous malformation size, deep location, and associated arterial aneurysms.

RESULTS

Evidence of old hemorrhage was present in 6.5% (n=975) of patients and highly predictive of index ICH (P<0.001; OR, 3.97; 95% CI, 2.1-7.5) adjusting for other risk factors. In a multivariable model (n=643), evidence of old hemorrhage was an independent predictor of new ICH (hazard ratio, 3.53; 95% CI, 1.35-9.23; P=0.010). Hemosiderin positivity was found in 36.2% (29.6% in unruptured; 47.8% in ruptured; P=0.04) and associated with index ICH in univariate (OR, 2.18; 95% CI, 1.03-4.61; P=0.042; n=127) and multivariable models (OR, 3.64; 95% CI, 1.11-12.00; P=0.034; n=79).

CONCLUSIONS

The prevalence of silent intralesional microhemorrhage is high and there is evidence for an association with both index and subsequent ICH. Further development of means to detect silent intralesional microhemorrhage during brain arteriovenous malformation evaluation may present an opportunity to improve risk stratification, especially for unruptured brain arteriovenous malformations.

Brain arteriovenous malformation multiplicity predicts the diagnosis of hereditary hemorrhagic telangiectasia: quantitative assessment

BACKGROUND AND PURPOSE

The purpose of this study was to quantitatively estimate the relationship between multiplicity of brain arteriovenous malformations (bAVMs) and the diagnosis of hereditary hemorrhagic telangiectasia (HHT).

METHODS

We combined databases from 2 large North American bAVM referral centers, including demographics, clinical presentation, and angiographic characteristics, and compared patients with HHT with non-HHT patients. Logistic regression analysis was performed to quantify the association between bAVM multiplicity and odds of HHT diagnosis. Sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratios were calculated to determine accuracy of bAVM multiplicity for screening HHT.

RESULTS

Prevalence of HHT was 2.8% in the combined group. bAVM multiplicity was present in 39% of patients with HHT and was highly associated with diagnosis of HHT in univariate (OR, 83; 95% CI, 40-173; P<0.0001) and multivariable (OR, 86; 95% CI, 38-195; P<0.001) models adjusting for age at presentation (P=0.013), symptomatic presentation (P=0.029), and cohort site (P=0.021). bAVM multiplicity alone was associated with high specificity (99.2%; 95% CI, 98.7%-99.6%) and negative predictive value (98.3%; 95% CI, 97.6%-98.8%) and low sensitivity (39.3%; 95% CI, 26.5%-53.2%) and positive predictive value (59.5%; 95% CI, 42.1%-75.2%). Positive and negative likelihood ratio was 51 and 0.61, respectively, for diagnosis of HHT. HHT bAVMs were also more often smaller in size (<3 cm), noneloquent in location, and associated with superficial venous drainage compared with non-HHT bAVMs.

CONCLUSIONS

Multiplicity of bAVMs is highly predictive of the diagnosis of HHT. The presence of multiple bAVMs should alert the clinician to the high probability of HHT and lead to comprehensive investigation for this diagnosis.

Polymorphisms of VEGFA gene and susceptibility to hemorrhage risk of brain arteriovenous malformations in a Chinese population

AIM

To evaluate the influence of the vascular endothelial growth factor A (VEGFA) polymorphisms on risk of presentation with intracerebral hemorrhage (ICH).

METHODS

Nine selected VEGFA single-nucleotide polymorphisms (SNPs) were genotyped in 311 patients with brain arteriovenous malformations (BAVM) in a Chinese population. Associations between individual SNPs/haplotypes and the hemorrhage risk of BAVMs were evaluated using logistic regression analysis.

RESULTS

In the single-locus analysis, rs1547651 was associated with increased risk of ICH (adjusted OR=2.11, 95% CI=1.01-4.42 compared with the AA genotype). In particular, an increased risk for ICH was associated with this variant in female patients (adjusted OR=3.21, and 95% CI=0.99-10.36). Haplotype-based analyses revealed that haplotype 'GC' in block 1 and haplotype 'ACC' in block 2 were associated with a 30%-38% reduction in the risk of ICH in patients with BAVMs compared to the most common haplotype (P(sim)=0.033 and P(sim)=0.005, respectively). The protective effect of haplotype 'ACC' in block 2 was more evident in male patients and subjects with BAVMs of a size ≥3 cm (adjusted OR=0.57, 95% CI=0.34-0.97 and adjusted OR=0.57, 95% CI=0.31-0.86, respectively).

CONCLUSION

The results suggest that VEGFA gene variants may contribute to ICH risk of BAVM.

Arteriovenous malformation in the adult mouse brain resembling the human disease

OBJECTIVE

Brain arteriovenous malformations (bAVMs) are an important cause of hemorrhagic stroke. The underlying mechanisms are not clear. No animal model for adult bAVM is available for mechanistic exploration. Patients with hereditary hemorrhagic telangiectasia type 2 (HHT2) with activin receptor-like kinase 1 (ALK1; ACVRL1) mutations have a higher incidence of bAVM than the general population. We tested the hypothesis that vascular endothelial growth factor (VEGF) stimulation with regional homozygous deletion of Alk1 induces severe dysplasia in the adult mouse brain, akin to human bAVM.

METHODS

Alk1(2f/2f) (exons 4-6 flanked by loxP sites) and wild-type (WT) mice (8-10 weeks old) were injected with adenoviral vector expressing Cre recombinase (Ad-Cre; 2 × 10(7) plaque forming units [PFU]) and adeno-associated viral vectors expressing VEGF (AAV-VEGF; 2 × 10(9) genome copies) into the basal ganglia. At 8 weeks, blood vessels were analyzed.

RESULTS

Gross vascular irregularities were seen in Alk1(2f/2f) mouse brain injected with Ad-Cre and AAV-VEGF. The vessels were markedly enlarged with abnormal patterning resembling aspects of the human bAVM phenotype, displayed altered expression of the arterial and venous markers (EphB4 and Jagged-1), and showed evidence of arteriovenous shunting. Vascular irregularities were not seen in similarly treated WT mice.

INTERPRETATION

Our data indicate that postnatal, adult formation of the human disease, bAVM, is possible, and that both genetic mutation and angiogenic stimulation are necessary for lesion development. Our work not only provides a testable adult mouse bAVM model for the first time, but also suggests that specific medical therapy can be developed to slow bAVM growth and potentially stabilize the rupture-prone abnormal vasculature.

Angiopoietin-like 4 (ANGPTL4) gene polymorphisms and risk of brain arteriovenous malformations

BACKGROUND

Brain arteriovenous malformations (BAVM) are high-flow vascular lesions prone to intracranial hemorrhage (ICH). Abnormal angiogenesis is a key characteristic of BAVM tissue. Angiopoietin-like 4 (ANGPTL4), a secreted glycoprotein, is thought to be involved in angiogenesis and required for proper postnatal blood vessel partitioning. We investigated whether common single nucleotide polymorphisms (SNPs) in ANGPTL4 were associated with risk of BAVM or ICH.

METHODS AND RESULTS

We conducted a case-control study of 216 Caucasian BAVM cases and 246 healthy controls, and a secondary case-only analysis, comparing 83 ruptured (ICH) with 133 unruptured BAVM cases at presentation. Four tagSNPs in ANGPTL4 captured variation over a 10-kb region (rs2278236, rs1044250, rs11672433, and rs1808536) and were tested for association with BAVM or ICH. The minor allele (A) of rs11672433 (exon 6, Pro389Pro) was associated with an increased risk of BAVM (p = 0.006), which persisted after adjusting for multiple comparisons (p = 0.03). After adjustments for age and sex, carriers of the minor allele (A) remained at higher risk for BAVM compared to noncarriers (odds ratio, OR = 1.56; 95% confidence interval, CI = 1.01-2.41; p = 0.046) and risk of BAVM was increased with increasing copy of the minor A allele (OR = 1.49, 95% CI = 1.03-2.15; p(trend) = 0.03). Five common haplotypes (frequency >1%) were inferred; overall haplotype distribution differed between BAVM cases and controls (χ(2) = 12.2, d.f. = 4, p = 0.02). Neither SNPs (p > 0.05) nor haplotype distribution (χ(2) = 1.1, d.f. = 4, p = 0.89) were associated with risk of ICH among BAVM cases.

CONCLUSION

A synonymous SNP in ANGPTL4 and haplotypes carrying it are associated with risk of BAVM but not with ICH presentation in BAVM cases.

Cerebral haemorrhage from a remote varix in the venous outflow of an arteriovenous malformation treated successfully by embolisation

We describe a case of intracerebral haemorrhage in the temporal lobe arising from a distal varix related to the venous outflow of an ipsilateral frontal arteriovenous malformation (AVM). AVM itself and associated arterial aneurysms are well-known risk factors for haemorrhage. In this patient, haemorrhage had occurred from a distal varix. This is the first reported case of successful endovascular embolisation of a frontal AVM with spontaneous regression of an associated remote varix. [corrected].

Interventions for treating brain arteriovenous malformations in adults

BACKGROUND

Brain arteriovenous malformations (AVMs) are the single most common cause of intracerebral haemorrhage in young adults. Brain AVMs also cause seizure(s) and focal neurological deficits (in the absence of haemorrhage, migraine or an epileptic seizure); approximately one fifth are incidental discoveries. Various interventions are used in an attempt to eradicate brain AVMs: neurosurgical excision, stereotactic radiotherapy/'radiosurgery' (using gamma knife, linear accelerator, proton beam, or 'Cyber Knife'), endovascular embolisation (using glues, particles, fibres, coils, or balloons), and staged combinations of these interventions. This is an update of a Cochrane review first published in 2006.

OBJECTIVES

To assess the clinical effects of interventions to treat brain AVMs in adults (with the aim of either partial obliteration or total eradication), using data published in randomised controlled trials (RCTs).

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched November 2009), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 4, 2009), MEDLINE (1966 to November 2009) and EMBASE (1980 to November 2009). We searched international registers of clinical trials, the contents pages of relevant journals, and bibliographies of relevant articles (November 2009). We also contacted manufacturers of interventional treatments for brain AVMs (March 2005).

SELECTION CRITERIA

We sought randomised trials of any or all of the interventions for brain AVMs, compared against each other or against usual medical therapy, with relevant clinical outcome measures.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the inclusion criteria and reviewed the relevant studies.

MAIN RESULTS

One ongoing RCT fulfils the selection criteria for this review: A Randomized trial of Unruptured Brain Arteriovenous malformations (ARUBA, www.arubastudy.org), comparing interventional treatment versus medical management for brain AVMs that have never bled. We also found two RCTs which tested the equivalence of two embolic agents for the pre-operative embolisation of brain AVMs (one published, one unpublished), but none of the primary or secondary outcome measures in these trials met our desired criteria. We also excluded a third RCT which studied three different blood pressure lowering treatments to induce deliberate hypotension during surgical resection of brain AVMs because the intervention was not the focus of this review.

AUTHORS' CONCLUSIONS

There is no evidence from randomised trials with clear clinical outcomes comparing different interventional treatments for brain AVMs against each other or against usual medical therapy to guide the interventional treatment of brain AVMs in adults. One such trial (ARUBA) is ongoing.

Angioarchitecture and clinical presentation of brain arteriovenous malformations

The purpose of this study was to correlate the angioarchitecture of brain arteriovenous malformations (AVM) with their clinical presentation. A total of 170 patients with AVM 78 males and 92 females, were studied. Univariate and multivariate analyses were conducted in order to test the associations between morphological features and clinical presentation. The most frequent clinical presentations at diagnosis were hemorrhage in 89 (52%) patients, headache in 79 (46%), focal neurological deficit in 54 (32%), and seizure in 52 (31%). According to the Spetzler-Martin classification, grade I was found in 15 patients, II in 49, III in 55, IV in 41, and grade V in 10 patients. AVM with small nidus size, single feeding artery and single draining vein were associated with hemorrhage. Hemorrhage was positively associated with Spetzler-Martin grade I and negatively with grade V. The association between seizure and large nidus size was positive, however negative with small nidus size.

Clinical and morphological determinants of focal neurological deficits in patients with unruptured brain arteriovenous malformation

OBJECTIVE

Some patients with brain arteriovenous malformation (BAVM) present with focal neurological deficits (FNDs) unrelated to clinically discernable seizure activity or hemorrhage. The aim of this study is to determine demographic and morphological AVM characteristics associated with FNDs.

METHODS

The 735 patients of the prospective Columbia AVM Databank were analyzed. Univariate and multivariate statistical models were used to test the association of demographic (age, gender), and morphological characteristics (BAVM size, anatomic location, arterial supply, venous drainage pattern, venous ectasia) with the occurrence of FNDs at the time of initial BAVM diagnosis.

RESULTS

Fifty-three patients (7%, mean age 40+/-16years, 70% women) presented with FNDs. The multivariate logistic regression model revealed an independent association of FNDs with increasing age (OR 1.03; 95%-CI 1.00-1.05), female gender (OR 2.14; 95%-CI 1.15-3.97), deep brain location (OR 2.46; 95%-CI 1.24-4.88), brainstem location (OR 5.62; 95%-CI 1.65-19.23), and venous ectasia (OR 1.91; 95%-CI 1.01-3.64). No association was found for BAVM size, lobar location, arterial supply and venous drainage pattern.

INTERPRETATION

Focal neurologic deficits unrelated to seizures or hemorrhage are a rare initial presentation of BAVMs. The predominance of FNDs among brainstem and deeply located BAVMs and the lack of a significant association of BAVM size with FNDs indicate selective white matter pathway-specific vulnerability, the association with patient age a time dependent effect. The higher frequency of FNDs among women suggests gender-specificity of brain tissue vulnerability.

EPHB4 gene polymorphisms and risk of intracranial hemorrhage in patients with brain arteriovenous malformations

BACKGROUND

Brain arteriovenous malformations (BAVMs) are a tangle of abnormal vessels directly shunting blood from the arterial to venous circulation and an important cause of intracranial hemorrhage (ICH). EphB4 is involved in arterial-venous determination during embryogenesis; altered signaling could lead to vascular instability resulting in ICH. We investigated the association of single-nucleotide polymorphisms (SNPs) and haplotypes in EPHB4 with risk of ICH at clinical presentation in patients with BAVM.

METHODS AND RESULTS

Eight haplotype-tagging SNPs spanning approximately 29 kb were tested for association with ICH presentation in 146 white patients with BAVM (phase I: 56 ICH, 90 non-ICH) using allelic, haplotypic, and principal components analysis. Associated SNPs were then genotyped in 102 additional cases (phase II: 37 ICH, 65 non-ICH), and data were combined for multivariable logistic regression. Minor alleles of 2 SNPs were associated with reduced risk of ICH presentation (rs314313_C, P=0.005; rs314308_T, P=0.0004). Overall, haplotypes were also significantly associated with ICH presentation (chi(2)=17.24, 6 df, P=0.008); 2 haplotypes containing the rs314308 T allele (GCCTGGGT, P=0.003; GTCTGGGC, P=0.036) were associated with reduced risk. In principal components analysis, 2 components explained 91% of the variance and complemented haplotype results by implicating 4 SNPs at the 5' end, including rs314308 and rs314313. These 2 SNPs were replicated in the phase II cohort, and combined data resulted in greater significance (rs314313, P=0.0007; rs314308, P=0.00008). SNP association with ICH presentation persisted after adjusting for age, sex, BAVM size, and deep venous drainage.

CONCLUSIONS

EPHB4 polymorphisms are associated with risk of ICH presentation in patients with BAVM, warranting further study.

Common variants in interleukin-1-Beta gene are associated with intracranial hemorrhage and susceptibility to brain arteriovenous malformation

BACKGROUND

Polymorphisms in the proinflammatory cytokine interleukin (IL)-1beta gene have been associated with systemic atherogenesis, thrombosis and rupture. The aim of this study was to investigate associations between single nucleotide polymorphisms (SNPs) in IL-1beta and intracranial hemorrhage (ICH) in the natural course of brain arteriovenous malformation (BAVM) patients.

METHOD

Two IL-1beta promoter SNPs (-511C-->T, -31T-->C) and 1 synonymous coding SNP in exon 5 at +3953C-->T (Phe) were genotyped in 410 BAVM patients. We performed a survival analysis of time to subsequent ICH, censoring cases at first treatment, death or last follow-up. A Cox regression analysis was performed to obtain hazard ratios (HRs) for genotypes adjusted for age, sex, Caucasian race/ethnicity and hemorrhagic presentation.

RESULTS

Subjects with the -31 CC genotype (HR = 2.7; 95% CI 1.1-6.6; p = 0.029) or the -511 TT genotype (HR = 2.6; 95% CI 1.1-6.5; p = 0.039) had a greater risk of subsequent ICH compared with reference genotypes, adjusting for covariates. The +3953C-->T SNP was not significantly associated with an increased ICH risk (p = 0.22). The IL-1beta promoter polymorphisms were also associated with BAVM susceptibility among a subset of 235 BAVM cases and 255 healthy controls of Caucasian race/ethnicity (p < 0.001).

CONCLUSION

IL-1beta promoter polymorphisms were associated with an increased risk of ICH in BAVM clinical course and with BAVM susceptibility. These results suggest that inflammatory pathways, including the IL-1beta cytokine, may play an important role in ICH.

Endothelial Notch4 signaling induces hallmarks of brain arteriovenous malformations in mice

Brain arteriovenous malformations (BAVMs) can cause devastating stroke in young people and contribute to half of all hemorrhagic stroke in children. Unfortunately, the pathogenesis of BAVMs is unknown. In this article we show that activation of Notch signaling in the endothelium during brain development causes BAVM in mice. We turned on constitutively active Notch4 (int3) expression in endothelial cells from birth by using the tetracycline-regulatable system. All mutants developed hallmarks of BAVMs, including cerebral arteriovenous shunting and vessel enlargement, by 3 weeks of age and died by 5 weeks of age. Twenty-five percent of the mutants showed signs of neurological dysfunction, including ataxia and seizure. Affected mice exhibited hemorrhage and neuronal cell death within the cerebral cortex and cerebellum. Strikingly, int3 repression resolved ataxia and reversed the disease progression, demonstrating that int3 is not only sufficient to induce, but also required to sustain the disease. We show that int3 expression results in widespread enlargement of the microvasculature, which coincided with a reduction in capillary density, linking vessel enlargement to Notch's known function of inhibiting vessel sprouting. Our data suggest that the Notch pathway is a molecular regulator of BAVM pathogenesis in mice, and offer hope that their regression might be possible by targeting the causal molecular lesion.

Outcome after interventional or conservative management of unruptured brain arteriovenous malformations: a prospective, population-based cohort study

BACKGROUND

The decision about whether to treat an unruptured brain arteriovenous malformation (AVM) depends on a comparison of the estimated lifetime risk of intracranial haemorrhage with the risks of interventional treatment. We aimed to test whether outcome differs between adults who had interventional AVM treatment and those who did not.

METHODS

All adults in Scotland who were first diagnosed with an unruptured AVM during 1999-2003 (n=114) entered our prospective, population-based study. We compared the baseline characteristics and 3-year outcome of adults who received interventional treatment for their AVM (n=63) with those who did not (n=51).

FINDINGS

At presentation, adults who were treated were younger (mean 40 vs 55 years of age, 95% CI for difference 9-20; p<0.0001), more likely to present with a seizure (odds ratio 2.4, 95% CI 1.1-5.0), and had fewer comorbidities (median 3 vs 4, p=0.03) than those who were not treated. Despite these baseline imbalances, treated and untreated groups did not differ in progression to Oxford Handicap Scale (OHS) scores of 2-6 (log-rank p=0.12) or 3-6 (log-rank p=0.98) in survival analyses. In a multivariable Cox proportional hazards analysis, the risk of poor outcome (OHS 2-6) was greater in patients who had interventional treatment than in those who did not (hazard ratio 2.5, 95% CI 1.1-6.0) and was greater in patients with a larger AVM nidus (hazard ratio 1.3, 95% CI 1.1-1.7). The treated and untreated groups did not differ in time to an OHS score of 2 or more that was sustained until the end of the third year of follow-up, or in the spectrum of dependence as measured by the OHS at 1, 2, and 3 years of follow-up.

INTERPRETATION

Greater AVM size and interventional treatment were associated with worse short-term functional outcome for unruptured AVMs, but the longer-term effects of intervention are unclear.

Association of tumor necrosis factor-alpha-238G>A and apolipoprotein E2 polymorphisms with intracranial hemorrhage after brain arteriovenous malformation treatment

OBJECTIVE

We previously reported specific genotypes of polymorphisms in two genes, tumor necrosis factor-alpha (TNF-alpha-238G > A) and Apolipoprotein E (ApoE e2), as independent predictors of new intracranial hemorrhage (ICH) in the natural course of untreated brain arteriovenous malformations. We hypothesized that the risk of posttreatment ICH would also be greater in patients with brain arteriovenous malformations with these genotypes.

METHODS

Two hundred fifteen patients undergoing brain arteriovenous malformation treatment (embolization, arteriovenous malformation resection, radiosurgery, or any combination of these) were genotyped and followed longitudinally. Association of genotype with new symptomatic ICH after initiation of treatment was assessed using Cox proportional hazards adjusted for treatment type, demographics, and established ICH risk factors censored at the time of the last follow-up evaluation or death.

RESULTS

The cohort was 48% male and 55% Caucasian, and 52% had an ICH before the initiation of treatment; the mean age +/- standard deviation was 36.6 +/- 17.2 years. Posttreatment ICH occurred in 34 (16%) patients with a median follow-up period of 1.9 years (interquartile range, 1.6 yr). After adjustment, the risk of posttreatment ICH was greater for TNF-alpha-238 AG genotype (hazard ratio [HR], 3.5; 95% confidence interval [CI], 1.3-9.8; P = 0.016) and ApoE e2 (HR, 3.2; 95% CI, 1.0-9.7; P = 0.042). Similar trends for the TNF-alpha-238 AG genotype were seen in surgery (HR, 4.2; 95% CI, 0.6-28.8; P = 0.14) and radiosurgery subsets (HR, 3.8; 95% CI, 0.7-19.4; P = 0.11). An effect of ApoE e2 was seen in radiosurgery subsets (HR, 10.9; 95% CI, 1.3-93.7; P = 0.030), but not in surgery subsets (HR, 1.4; 95% CI, 0.3-7.4; P = 0.67).

CONCLUSION

Despite a variety of different mechanisms for posttreatment hemorrhage, these data suggest that the TNF-alpha and ApoE genotypes may contribute common phenotypes of enhanced vascular instability that increase the risk of hemorrhagic outcome.

A framework for improving radiology reporting

The interpretative reports rendered by radiologists are the only tangible manifestation of their expertise, training, and experience. These documents are very often the primary means by which radiologists provide patient care. Radiology reports are extremely variable in form, content, and quality. The authors propose a framework for conceptualizing the reporting process and how it might be improved. This consists of standard language, a structured format, and consistent content. These attributes will be realized by modifying the clinical reporting process, including the creation, storage, transmission, and review of interpretative documents. The authors also point out that changes in training and evaluation must be a part of the process, because they are complementary to purely technical solutions.

PREOPERATIVE EMBOLIZATION OF INTRACRANIAL ARTERIOVENOUS MALFORMATIONS WITH ONYX

OBJECTIVE

Preoperative embolization in accordance with multimodal therapies for cerebral arteriovenous malformations (AVMs) is generally the first step in treatment and may result in complete obliteration. The Onyx liquid embolic system (Micro Therapeutics, Inc., Irvine, CA) may offer advantages for intranidal targeted embolization and microsurgical resection. We present our experience in the combined treatment of intracranial AVMs using Onyx embolization and neurosurgical resection.

METHODS

We treated a total of 47 patients for compact intracranial AVMs that were located in the frontal or frontoparietal area (16 patients); temporal, temporoparietal, or temporo-occipital regions (12 patients); parietal or parieto-occipital areas (8 patients); occipital regions (8 patients); had basal ganglia involvement (2 patients); and was cerebellar (1 patient). The Spetzler-Martin grading scale values were as follows: 25 patients were Grades I or II, 10 patients were Grade III, and 12 patients were Grades IV or V. Twenty-three AVMs were located in eloquent brain regions.

RESULTS

After we performed final embolizations, the mean nidus reduction was 84%. Seven patients had new, nondisabling neurological deficits, and four patients had new, disabling neurological deficits after embolization. Periprocedurally, five vessel perforations and four stuck microcatheters were encountered without clinical deficits. In two patients, delayed hemorrhage after embolization occurred with good clinical outcome. We completely resected 46 AVMs; in one patient, we detected an AVM on postoperative angiography. The mean operative time was 4.7 hours, and the mean blood loss was 455 mL. Clinical status worsened postoperatively in 14 patients. Angiographic and clinical follow-up examinations were available for 42 patients (89%); the average follow-up period was 13 months. We found no relapse of arteriovenous shunt. Fourteen patients improved clinically after discharge. Of the 42 patients followed up, 23 individuals had no neurological deficit, 16 had a nondisabling deficit, and three had a disabling deficit.

CONCLUSION

Preoperative use of the Onyx liquid embolic system in cerebral AVM treatment allows profound occlusion by targeted embolization and provides a basis for safe neurosurgical resection.

Interleukin-6 upregulates expression of KDR and stimulates proliferation of human cerebrovascular smooth muscle cells

Interleukin-6 (IL-6) may play multiple roles in angiogenesis and vascular remodeling. Our previous study showed that a promoter polymorphism (174G>C) in IL-6 is associated with brain arteriovenous malformation hemorrhage; tissue expression is related to genotype. In this study, we investigated the effects of IL-6 on human cerebral smooth muscle cells (HCSMCs) and smooth muscle cells isolated from brain arteriovenous malformation surgical specimens (AVM SMCs) and surgical controls (control HCSMCs--from structurally normal temporal lobe taken during surgical treatment of epilepsy patients). We found that IL-6 (1.1+/-0.27 versus 0.37+/-0.04 pg/mL, n=5, P<0.05) and endogenous vascular endothelial growth factor (VEGF) receptor II (kinase domain-containing receptor (KDR), 15+/-3 versus 1.5+/-3 pg/mL, n=5, P<0.05) were increased in brain AVM SMCs compared with control HCSMCs. Further research revealed that IL-6 could stimulate SMC proliferation, VEGF release, and KDR activation in control HCSMCs. It could also stimulate KDR phosphorylation in control HCSMCs, further confirming a unique role of IL-6 in the triggering of KDR. Interleukin-6 could increase matrix metalloproteinase-9 (MMP-9) secretion through activating KDR in control HCSMCs (P<0.05 versus control). Inhibiting IL-6-induced KDR could reduce MMP-9 activity at least 50% compared with the control group (P<0.05). Increased MMP-9 activity was accompanied by increased control HCSMC proliferation, and blocking MMP-9 activity significantly reduced IL-6-induced control HCSMC proliferation (P<0.05). Collectively, our results show that IL-6 could activate, amplify, and maintain the angiogenic cascade in HCSMCs. A novel role of IL-6 during HCSMC proliferation is upregulating KDR expression and phosphorylation. The results may contribute to the angiogenic phenotype of human brain vascular diseases, such as brain AVM.

Neurologie des malformations artérioveineuses cérébrales

INTRODUCTION

Brain arteriovenous malformations (AVMs) constitute a neurovascular disorder that comes to clinical attention mainly in young adults in their mid thirties. Associated symptoms often require neurological treatment for symptomatic seizures (focal or generalized), headaches (episodic or chronic), progressive neurological deficits, or spontaneous AVM rupture leading to intracerebral, intraventricular, and/or subarachnoid hemorrhage.

STATE OF ART

Little data exist in the medical literature regarding the natural history risk of the disease and no controlled studies are available on the risk of invasive AVM treatment (endovascular, neurosurgery, radiotherapy).

PERSPECTIVES

This review focuses on all aspects of neurological brain AVM management and discusses possible predictors of the natural history risk as well as the benefit and risk of invasive treatment.

CONCLUSIONS

AVM patient management is ideally based on a trans-disciplinary approach via a neurovascular team of neurologists, neuroradiologists, neurosurgeons, and radiotherapists. A newly diagnosed AVM does not necessarily represent an a priori indication for interventional treatment. The decision in favor or against therapy mainly depends on clinical criteria (ruptured versus unruptured AVM, neurological exam, patient age and co-morbidity, etc.) and the angioarchitecture of the malformation. The ARUBA study is going to be the first randomized clinical trial comparing the risk of invasive treatment versus non-invasive management.

Apolipoprotein E epsilon 2 is associated with new hemorrhage risk in brain arteriovenous malformations

OBJECTIVE

Patients with brain arteriovenous malformation (AVM) are at life-threatening risk of intracranial hemorrhage (ICH). Identification of genetic variants associated with increased new ICH risk would facilitate risk stratification and guide therapeutic intervention.

METHODS

Brain AVM patients evaluated at University of California, San Francisco or Kaiser Permanente Northern California were followed longitudinally. Primary outcome was new ICH after diagnosis; censoring events were any AVM treatment or last follow-up examination. The association of ApoE epsilon2 and epsilon4 genotype with new ICH was evaluated by Kaplan-Meier survival analysis and further characterized via a Cox proportional hazards model.

RESULTS

We genotyped 284 brain AVM patients (50% women; 57% Caucasian; median follow-up time, 0.3 yr) including 18 patients with a history of new ICH). ApoE epsilon2, but not ApoE epsilon4 genotype, was associated with new ICH (P = 0.0052). ApoE epsilon2 carriers had fivefold increased risk of new ICH (hazard ratio, 5.09; 95% confidence interval, 1.46-17.7; P = 0.010; Cox proportional hazards model adjusting for race/ethnicity and clinical presentation). Subset analysis in the largest homogenous ethnic subcohort (Caucasians) confirmed the increased risk of new ICH in ApoE epsilon2 carriers (hazard ratio, 8.71; 95% confidence interval, 1.4-53.9; P = 0.020; multivariate model adjusting for clinical presentation).

CONCLUSION

ApoE genotype may influence the risk of ICH in the natural course of brain AVM. The identification of genetic predictors of ICH risk may facilitate estimation of AVM natural history risk and individualize clinical decision-making and therapeutic recommendations.

Interventions for treating brain arteriovenous malformations in adults

BACKGROUND

Brain arteriovenous malformations (AVMs) are the single most common cause of intracerebral haemorrhage in young adults. Brain AVMs also cause seizure(s) and focal neurological deficits (in the absence of haemorrhage, migraine or an epileptic seizure); approximately one fifth are incidental discoveries. Various interventions are used in an attempt to eradicate brain AVMs: neurosurgical excision, stereotactic radiotherapy/'radiosurgery' (using gamma knife, linear accelerator or proton beam), endovascular embolisation (using glues, particles, fibres, coils, or balloons), and staged combinations of these interventions.

OBJECTIVES

To assess the clinical effects of interventions to treat brain AVMs in adults (with the aim of either partial obliteration or total eradication), using data published in randomised controlled trials.

SEARCH STRATEGY

We searched: (1) the Cochrane Stroke Group Register (last searched December 2004); (2) medical literature databases (MEDLINE 1966 to 31 December 2004 and EMBASE 1980 to 31 December 2004); (3) on-line and paper journal surveillance; (4) the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2005); (5) international registers of clinical trials; (6) bibliographies of relevant articles identified by (1) to (5); and (7) we sought unpublished data from manufacturers of interventional treatments for brain AVMs.

SELECTION CRITERIA

We sought randomised trials of any or all of the interventions for brain AVMs, compared against each other or against usual medical therapy, with relevant clinical outcome measures.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the inclusion criteria and reviewed the relevant studies.

MAIN RESULTS

We did not find any randomised trials meeting our selection criteria. We found two randomised trials which tested the equivalence of two embolic agents for the pre-operative embolisation of brain AVMs (one published, one unpublished), but none of the primary or secondary outcome measures in these trials met our desired criteria; although important clinical outcomes were reported, meaningful comparison of the two treatment arms was impossible. We also excluded a third RCT which studied three different blood pressure lowering treatments to induce deliberate hypotension during surgical resection of brain AVMs, because the intervention was not the focus of this review.

AUTHORS' CONCLUSIONS

There is no evidence from randomised trials with clear clinical outcomes, comparing different interventional treatments for brain AVMs against each other or against usual medical therapy, to guide the interventional treatment of brain AVMs in adults. One such trial (ARUBA), comparing interventional versus conservative management for unruptured brain AVMs, is being planned.

Suppression of MMP-9 by doxycycline in brain arteriovenous malformations

Background

The primary aim of this study is to demonstrate the feasibility of utilizing doxycycline to suppress matrix metalloproteinase-9 (MMP-9) in brain arteriovenous malformations (AVMs).

Methods

Ex-vivo treatment of AVM tissues: Intact AVM tissues were treated with doxycycline for 48 hours. Active and total MMP-9 in the medium were measured. Pilot trial: AVM patients received either doxycycline (100 mg) or placebo twice a day for one week prior to AVM resection. Active and total MMP-9 in BVM tissues were measured.

Results

Ex-vivo treatment of AVM tissues: Doxycycline at 10 and 100 μg/ml significantly decreased MMP-9 levels in AVM tissues ex-vivo (total: control vs 10 vs 100 μg/ml = 100 ± 6 vs 60 ± 16 vs 61 ± 9%; active: 100 ± 8 vs 48 ± 16 vs 59 ± 10%). Pilot trial: 10 patients received doxycycline, and 4 patients received placebo. There was a trend for both MMP-9 levels to be lower in the doxycycline group than in the placebo group (total: 2.18 ± 1.94 vs 3.26 ± 3.58, P = .50; active: 0.48 ± 0.48 vs 0.95 ± 1.01 ng/100 μg protein, P = .25).

Conclusions

A clinically relevant concentration of doxycycline decreased MMP-9 in ex-vivo AVM tissues. Furthermore, there was a trend that oral doxycycline for as short as one week resulted in a decrease in MMP-9 in AVM tissues. Further studies are warranted to justify a clinical trial to test effects of doxycycline on MMP-9 expression in AVM tissues.

THE RELATIONSHIP OF COEXISTING EXTRANIDAL ANEURYSMS TO INTRACRANIAL HEMORRHAGE IN PATIENTS HARBORING BRAIN ARTERIOVENOUS MALFORMATIONS

OBJECTIVE

We hypothesized that coexisting extranidal arterial aneurysms (EAs) would be associated with an increased risk of incident intracranial hemorrhage (ICH) from brain arteriovenous malformation (BAVM) rupture.

METHODS

To determine the presence of EAs and compare the sources and locations of ICH, we retrospectively reviewed the computed tomographic, magnetic resonance imaging, and angiographic studies of patients who presented between 1990 and 1999. EAs were defined as saccular luminal dilations of the parent feeding vessels that were proximally flow-related (i.e., at the circle of Willis), distally flow-related (i.e., distal to the circle of Willis), and unrelated (i.e., in circulation distant from the BAVM).

RESULTS

Of 314 BAVM patients, 138 (44%) presented with ICH. In the ICH group, 22 patients (16%) had aneurysmal ICH, 100 (72%) had BAVM ICH, and 16 (12%) had ICH from an indeterminate source. There were 61 patients with 1 or more EAs (29 patients with 42 flow-related proximal aneurysms, 39 patients with 48 flow-related distal aneurysms, and 10 patients with 20 unrelated aneurysms). Multivariate regression analysis revealed that ICH patients were more likely than non-ICH patients to have a coexisting EA (35 versus 13%; odds ratio = 3.9; 95% confidence interval, 2.1-7.5; P < 0.001), but this effect was not present when only BAVM-related ICH was considered (odds ratio = 0.3; 95% confidence interval, 0.1-1.0; P = 0.052). Other independent predictors of ICH included small AVM size (<3 cm), exclusively deep venous drainage, and the presence of an intranidal aneurysm.

CONCLUSION

Clinical presentation with ICH was associated with EA aneurysms, but the association was due to aneurysmal rather than BAVM rupture, suggesting that EAs and the BAVM ICH risks may be considered as separate entities in future studies.

Radiologic findings and clinical significance of venous compartment of brain arteriovenous shunts

The venous compartment of brain AVS is closely related to the development of various clinical consequences, including hemorrhage, seizure, and neurologic deficit. Therefore, understanding the venous etiology of the clinical symptoms and the imaging characteristics of partial or complete venous outlet thrombosis is critical for the proper management of patients with brain AVSs.

Arteriovenous Malformations in the Brain

Arteriovenous malformations (AVM) are a leading cause of intracerebral hemorrhage, especially among the young. Because they pose a lifelong risk of serious bleeding, definitive treatment to obliterate the AVM should be pursued in the majority of patients. Microsurgical resection of a small AVM located in the superficial or non- eloquent brain achieves high cure rates with low morbidity, and is the recommended choice for such lesions. Radiosurgery with gamma knife, linear accelerator, or heavy ion beam irradiation is an alternative therapy for AVM treatments less than 3 centimeters in diameter located in brain regions where surgery is likely to produce major neurologic deficits, or for patients unable or unwilling to undergo craniotomy and resection. Cure rates are lower than with microsurgery, and obliteration of the lesion may take 2 to 3 years, during which time the patient remains at risk for hemorrhage. Because rates of recurrent hemorrhage are higher than rates of initial bleeding, radiosurgery may be a good option for patients who have not yet had an intracranial hemorrhage. Endovascular embolization as sole therapy is curative only in a small percentage of cases, but is recommended as part of a multimodal approach to reduce the size of a large AVM, and decrease bleeding risk of lesions with multiple or inaccessible feeding vessels or associated aneurysms prior to surgery or radiotherapy. Currently, treatment decisions must rely solely on Class III evidence from case series and expert opinion. Randomized clinical trials are needed to provide objective guidelines for the future management of patients with an AVM.

Interventional neuroradiology--anesthetic considerations

Interventional neuroradiologic procedure represents treatment of central nervous system disease by endovascular access for the purpose of delivering therapeutic agents, including both drugs and devices. For optimal anesthetic management, anesthesiologists should be familiar with specific radiological procedures and their potential complications. This article provides a brief overview of special considerations in conducting general anesthesia, sedation, and cerebral hemodynamic monitoring for patients undergoing interventional neuroradiologic procedures.

Dopplersonographic measurement of global cerebral circulation time using echo contrast-enhanced ultrasound in normal individuals and patients with arteriovenous malformations

Echo-contrast "bolus tracking" by ultrasound (US) is an exciting new tool to study cerebral haemodynamics. In the present study, a global cerebral circulation time (CCT) was measured by extracranial Doppler as the time difference of contrast bolus arrival between the internal carotid artery and internal jugular vein. A total of 64 healthy volunteers and 9 patients with an angiographically diagnosed arteriovenous malformation (AVM) were studied. CCT in volunteers and patients was calculated as the time interval between the points of 10% rise (CCT(1)) and 90% rise (CCT(3)) of the total intensity increase and between the turning points (CCT(2)) of the resulting time-intensity curves. In the volunteer group, CCT(1) was 5.4 +/- 1.8 s, CCT(2) was 7 +/- 1.3 s and CCT(3) 7.5 +/- 1.8 s. CCT results in the AVM group were 2.8 +/- 2.5 s, 3.0 +/- 1.3 s and 4.5 +/- 2.1 s, respectively, and differed significantly from the controls. For the first time, we could confirm a significant shortening of CCT in patients with cerebral AVM by US. The presented test might become a new, additional tool for AVM evaluation and follow-up of treatment in these patients.