Assessing the rate, natural history, and treatment trends of intracranial aneurysms in patients with intracranial dural arteriovenous fistulas: a Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR) investigation
Authors: Abecassis Isaac Josh , Meyer R. Michael , Levitt Michael R. , Sheehan Jason P. , Chen Ching-Jen , Gross Bradley A. , Lockerman Ashley , Fox W. Christopher , Brinjikji Waleed , Lanzino Giuseppe , Starke Robert M. , Chen Stephanie H. , Potgieser Adriaan R. E. , van Dijk J. Marc C. , Durnford Andrew , Bulters Diederik , Satomi Junichiro , Tada Yoshiteru , Kwasnicki Amanda , Amin-Hanjani Sepideh , Alaraj Ali , Samaniego Edgar A. , Hayakawa Minako , Derdeyn Colin P. , Winkler Ethan , Abla Adib , Lai Pui Man Rosalind , Du Rose , Guniganti Ridhima , Kansagra Akash P. , Zipfel Gregory J. , Kim Louis J. , _ _ , _ _ , Zipfel Gregory J. , Kansagra Akash P. , Guniganti Ridhima , Piccirillo Jay F. , Raman Hari , Lipsey Kim , Lanzino Giuseppe , Giordan Enrico , Brinjikji Waleed , Vine Roanna , Cloft Harry J. , Kallmes David F. , Pollock Bruce E. , Link Michael J. , Sheehan Jason , Chen Ching-Jen , Patibandla Mohana Rao , Ding Dale , Buell Thomas , Paisan Gabriella , Kim Louis J. , Levitt Michael R. , Abecassis Isaac Josh , Meyer R. Michael , Kelly Cory , Bulters Diederik , Durnford Andrew , Duffill Jonathan , Ditchfield Adam , Millar John , Macdonald Jason , Fox W. Christopher , Polifka Adam J. , Laurent Dimitri , Hoh Brian , Smith Jessica , Lockerman Ashley , Gross Bradley A. , Lunsford L. Dade , Jankowitz Brian T. , Hayakawa Minako , Derdeyn Colin P. , Samaniego Edgar A. , Gutierrez Santiago Ortega , Hasan David , Roa Jorge A. , Rossen James , Guerrero Waldo , McGruder Allen , Amin-Hanjani Sepideh , Alaraj Ali , Kwasnicki Amanda , Charbel Fady T. , Aletich Victor A. , Rose-Finnell Linda , van Dijk J. Marc C. , Potgieser Adriaan R. E. , Starke Robert M. , Peterson Eric C. , Yavagal Dileep R. , Sur Samir , Chen Stephanie H. , Satomi Junichiro , Tada Yoshiteru , Kanematsu Yasuhisa , Yamamoto Nobuaki , Kinouchi Tomoya , Korai Masaaki , Yamaguchi Izumi , Yamamoto Yuki , Abla Adib , Winkler Ethan , Phelps Ryan R. L. , Lawton Michael , Rutkowski Martin , Du Rose , Lai Pui Man Rosalind , Aziz-Sultan M. Ali , Patel Nirav , Frerichs Kai U. 
Published: September 2021

OBJECTIVE
There is a reported elevated risk of cerebral aneurysms in patients with intracranial dural arteriovenous fistulas (dAVFs). However, the natural history, rate of spontaneous regression, and ideal treatment regimen are not well characterized. In this study, the authors aimed to describe the characteristics of patients with dAVFs and intracranial aneurysms and propose a classification system.

METHODS
The Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR) database from 12 centers was retrospectively reviewed. Analysis was performed to compare dAVF patients with (dAVF+ cohort) and without (dAVF-only cohort) concomitant aneurysm. Aneurysms were categorized based on location as a dAVF flow-related aneurysm (FRA) or a dAVF non–flow-related aneurysm (NFRA), with further classification as extra- or intradural. Patients with traumatic pseudoaneurysms or aneurysms with associated arteriovenous malformations were excluded from the analysis. Patient demographics, dAVF anatomical information, aneurysm information, and follow-up data were collected.

RESULTS
Of the 1077 patients, 1043 were eligible for inclusion, comprising 978 (93.8%) and 65 (6.2%) in the dAVF-only and dAVF+ cohorts, respectively. There were 96 aneurysms in the dAVF+ cohort; 10 patients (1%) harbored 12 FRAs, and 55 patients (5.3%) harbored 84 NFRAs. Dural AVF+ patients had higher rates of smoking (59.3% vs 35.2%, p < 0.001) and illicit drug use (5.8% vs 1.5%, p = 0.02). Sixteen dAVF+ patients (24.6%) presented with aneurysm rupture, which represented 16.7% of the total aneurysms. One patient (1.5%) had aneurysm rupture during follow-up. Patients with dAVF+ were more likely to have a dAVF located in nonconventional locations, less likely to have arterial supply to the dAVF from external carotid artery branches, and more likely to have supply from pial branches. Rates of cortical venous drainage and Borden type distributions were comparable between cohorts. A minority (12.5%) of aneurysms were FRAs. The majority of the aneurysms underwent treatment via either endovascular (36.5%) or microsurgical (15.6%) technique. A small proportion of aneurysms managed conservatively either with or without dAVF treatment spontaneously regressed (6.2%).

CONCLUSIONS
Patients with dAVF have a similar risk of harboring a concomitant intracranial aneurysm unrelated to the dAVF (5.3%) compared with the general population (approximately 2%–5%) and a rare risk (0.9%) of harboring an FRA. Only 50% of FRAs are intradural. Dural AVF+ patients have differences in dAVF angioarchitecture. A subset of dAVF+ patients harbor FRAs that may regress after dAVF treatment.