Incident Hemorrhage Risk of Brain Arteriovenous Malformations Located in the Arterial Borderzones

Background and Purpose-To clarify hemodynamic risk factors for hemorrhage in arteriovenous malformations (AVMs), the mean transit time (MTT) of feeding arteries and draining veins in AVMs with and without hemorrhage was measured and analyzed. Methods-Morphological features such as the number and diameter of draining and feeding vessels and the AVM nidus volume were evaluated in 30 patients with supratentorial AVMs. The MTT of feeding arteries and draining veins was measured with the use of time-density curves obtained by digital subtraction angiography. The correlation between hemorrhage and morphology and hemorrhage and MTT was analyzed statistically. Results-The nidus volume was not significantly different between hemorrhagic and nonhemorrhagic AVMs. However, between ruptured and unruptured AVMs there was a significant difference in the mean number of draining veins (1.5Ϯ0.69 versus 2.3Ϯ0.50; Pϭ0.006), the MTT of the feeding artery (1.10Ϯ0.24 versus 1.62Ϯ0.55; Pϭ0.03), and the ratio of the MTT of the draining to the feeding vessels (1.71Ϯ0.43 versus 1.05Ϯ0.07; PϽ0.001). Conclusions-A high ratio of the MTT of draining veins to feeding arteries suggests disequilibrium between nidal inflow and outflow. The consequent increased pressure in the draining vein may contribute to the development of AVM hemorrhage.

Section: Discussionmentioning

confidence: 99%

Analysis of Mean Transit Time of Contrast Medium in Ruptured and Unruptured Arteriovenous Malformations

Todaka

Hamada

Kai

et al. 2003

“…24 Although there are no clear data about the absolute number of feeding or draining vessels carrying particular prognostic importance, future studies might profit from assessing the agreement about the original vascular territories of feeding vessels, because this may determine outcome. 32 Particular emphasis should be placed on developing internationally agreed-upon definitions 4 for the characteristics above and for those features that had the greatest interobserver variation in this study (angiopathy, angiogenesis, collateral supply, nidus border, discernible fistula, and venous stenosis). Thereafter, using our study as a baseline measure of observer agreement before to publication of the Joint Writing Group's definitions, 4 it will be important to reassess observer agreement in larger studies, among neuroradiologists from different countries, and using emerging techniques (such as MR and digital angiography, image manipulation, and reconstruction).…”

Section: Future Researchmentioning

confidence: 99%

Observer Agreement in the Angiographic Assessment of Arteriovenous Malformations of the Brain

Al‐Shahi

Pal

Lewis

et al. 2002

and the AVM Observer Agreement Study Group Purpose-We aimed to determine intraobserver and interobserver agreement in the characterization of brain arteriovenous malformation (AVM) angioarchitecture on intra-arterial digital subtraction angiograms. Methods-Five experienced interventional neuroradiologists independently reviewed 40 anonymized angiograms obtained at the time of first-ever AVM diagnosis. The allocation of the films to observers was balanced for AVM size and complexity. Every observer was compared with himself and all the others by distributing the films in 2 batches 3 months apart. The observers used standard forms to collect both quantitative and categorized qualitative angiographic data. To measure agreement we used the kappa statistic () for nominal data, weighted for ordinal and discrete interval data, and Bland & Altman analysis for continuous data. Results-Intraobserver agreement was generally moderate to substantial, with 95% confidence intervals ranging from fair to almost perfect. However, for every characteristic, interobserver agreement was less than intraobserver agreement.Interobserver agreement was generally slight to moderate, with 95% confidence intervals ranging from less than chance to almost perfect. Key Words: cerebral angiography Ⅲ cerebral arteriovenous malformations Ⅲ observer variation T he vascular anatomy (angioarchitecture) of brain arteriovenous malformations (AVMs) demonstrated on intraarterial digital subtraction angiograms is thought to influence their prognosis 1 and is therefore often used to decide whether and how to treat an AVM. 2,3 However, accurate description of angioarchitecture is inevitably affected by the inherent complexity of AVMs, neuroradiologists' personal interpretations, and human error. These sources of observer variation are likely to have been compounded by inconsistencies in angioarchitecture terminology used in the literature, varying perceptions of what is abnormal, and-until very recently-the lack of structured definitions intended for widespread use. 4 A recent systematic review revealed no published studies on MEDLINE and Embase of observer agreement in the angiographic assessment of AVMs. 1 We therefore sought to evaluate observer agreement using an approach that reflected day-to-day practice, minimized bias, and would not impose too great a burden on observers despite being powered adequately. Conclusion-This

“…7,23,24 Refining the understanding of why single venous drainage is associated with increased hemorrhage risk (increased outflow impedance) enabled the identification of confounders such as small nidal size, exclusively deep drainage, and deep location, characteristics that other studies have embraced as risk factors themselves. [3][4][5][6][7][9][10][11]13,[15][16][17]20,[22][23][24][25] Agreement analysis confirms that the statistically significant relationship of each of these bAVM characteristics with hemorrhage can be explained by significant association with parameters that play a plausible role in bAVM outflow impedance (number of draining veins, outflow stenosis), thus identifying these characteristics as confounders. This insight serves to clarify 30 although a plausible mechanism as to why deep venous drainage is associated with constrained outflow has not been proposed until now.…”

Section: Discussionmentioning

confidence: 87%

“…A substantial body of research has attempted to address this issue, [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] and many studies have found statistically significant associations between bAVM characteristics and hemorrhage risk. However, there is no clear rationale as to why many of the bAVM parameters studied might increase risk of rupture.…”

mentioning

confidence: 99%

“…However, there is no clear rationale as to why many of the bAVM parameters studied might increase risk of rupture. For example, bAVM nidal size, 3,6,9,10,13,15,[22][23][24][25] deep/only deep venous drainage, 3,[5][6][7]11,[13][14][15][16][17]22,26 deep location, 10,20 ventricular/ periventricular location, 4,7 posterior fossa location, 15,27 and arterial nonborderzone location 13 have all been statistically associated with rupture risk; however, the rationale for causality of these parameters is not entirely clear. In the absence of a clear mechanism to explain why these bAVM characteristics increase rupture risk, one cannot confidently use them to determine prospective hemorrhagic risk.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Features Predictive of Brain Arteriovenous Malformation Hemorrhage

Sahlein

Mora

Becske

et al. 2014

Background and Purpose-Although there is generally thought to be a 2% to 4% per annum rupture risk for brain arteriovenous malformations (bAVMs), there is no way to estimate risk for an individual patient. Methods-In this retrospective study, patients were eligible who had nidiform bAVMs and underwent detailed pretreatment diagnostic cerebral angiography at our medical center from 1996 to 2006. All patients had superselective microcatheter angiography, and films were reviewed for the purpose of this project. Patient demographics, clinical presentation, and angioarchitectural characteristics were analyzed. A univariate analysis was performed, and angioarchitectural features with potential physiological significance that showed at least a trend toward significance were added to a multivariate logistic regression model. Results-One hundred twenty-two bAVMs met criteria for study entry. bAVMs with single venous drainage anatomy were more likely to present with hemorrhage. In addition, patients with multiple draining veins and a venous stenosis reverted to a risk similar to those with 1 draining vein, whereas those with multiple draining veins and without stenosis had diminished association with hemorrhage presentation. Those bAVMs with associated aneurysms were more likely to present with hemorrhage. These findings were robust in both univariate and multivariate models. Conclusions-The