Imaging Characteristics of Growing and Ruptured Vertebrobasilar Non-Saccular and Dolichoectatic Aneurysms

Abstract

Background and Purpose— Vertebrobasilar, nonsaccular, and dolichoectatic aneurysms generally have a poor natural history. We performed a study examining the natural history of vertebrobasilar, nonsaccular, and dolichoectatic aneurysms receiving serial imaging and studied imaging characteristics associated with growth and rupture. Methods— We included all vertebrobasilar dolichoectatic, fusiform, and transitional aneurysms with serial imaging follow-up seen at our institution over a 15-year period. Two radiologists and a neurologist evaluated aneurysms for size, type, mural T1 signal, mural thrombus, daughter sac, mass effect, and tortuosity. Primary outcomes were aneurysm growth or rupture. Univariate analysis was performed with chi-squared tests for categorical variables and Student’s t test or analysis of variance for continuous variables. Multivariate logistic regression analysis was performed to identify variables independently associated with aneurysm growth or rupture. Results— One hundred and fifty-two patients with 542 patient-years (mean 3.6±3.5 years) of imaging follow-up were included. Aneurysms were fusiform in 45 cases (29.6%), dolichoectatic in 75 cases (49.3%), and transitional in 32 cases (21.1%). Thirty-five aneurysms (23.0%) grew (growth rate=6.5%/year). Eight aneurysms (5.3%) ruptured (rupture rate=1.5%/year). Variables associated with growth and rupture on univariate analysis were size >10 mm (57.6% versus 16.0%, P <0.0001), mural T1 signal (39.7% versus 16.3%, P =0.001), daughter sac (56.3% versus 21.3%), and mural thrombus (45.5% versus 13.4%, P <0.0001). 26.7% of fusiform aneurysms, 9.3% of dolichoectatic aneurysms, and 59.4% of transitional aneurysms grew or ruptured ( P <0.0001). The only variable independently associated with rupture was transitional morphology ( P =0.003). Conclusions— Vertebrobasilar, nonsaccular, and dolichoectatic aneurysms are associated with a poor natural history with high growth and rupture rates. Further research is needed to determine the best treatments for this disease.

Meta-analysis of treatment outcomes of posterior circulation non-saccular aneurysms by flow diverters

“…25 15 Meanwhile, fusiform aneurysms most frequently present with ischemic stroke symptoms (44%), or mass effect yielding cranial nerve palsies or hydrocephalus, and have a rupture rate of 1.7%/year. 26 16 Transitional aneurysms appear to have the least favorable natural histories with frequent aneurysm growth (15.8%/year) and high rupture rates (3.5%/year). 26 16 Among patients with aneurysms <10 mm, Nasr et al found that the annual rupture rate was just 0.6% per year compared with 6.8% per year for aneurysms 10 mm or larger.…”

Natural History of Vertebrobasilar Dolichoectatic and Fusiform Aneurysms: A Systematic Review and Meta-Analysis

“…Because VBDAs represent a wide variety of morphologic characteristics and have diverse etiologies, it is important to identify morphologic risk factors for progression [16, 18, 20]. As seen in our study, VBDAs of the pure dolichoectatic variety (i.e., tortuosity with uniform dilatation) have a completely different natural history than VBDAs of the fusiform variety.…”

“…As demonstrated by our study, there are at least 5 different definitions or criteria for what composes a VBDA [1-20]. In addition, the morphologic characteristics of these criteria can differ substantially.…”

“…This has been substantiated in a number of previously published studies. In a study of 151 VBDAs, Nasr et al [20] found that the rupture rate of dolichoectatic aneurysms was 0.4%/year compared to rates of 1.7%/year for fusiform aneurysms and 3.5%/year for transitional aneurysms. Likewise, the growth rate of dolichoectatic aneurysms is generally very low as Nasr et al [20] found a rate of 2.4%/year for dolichoectatic aneurysms compared to 6.4%/year for fusiform aneurysms and 15.8%/year for transitional aneurysms.…”

“…In a study of 151 VBDAs, Nasr et al [20] found that the rupture rate of dolichoectatic aneurysms was 0.4%/year compared to rates of 1.7%/year for fusiform aneurysms and 3.5%/year for transitional aneurysms. Likewise, the growth rate of dolichoectatic aneurysms is generally very low as Nasr et al [20] found a rate of 2.4%/year for dolichoectatic aneurysms compared to 6.4%/year for fusiform aneurysms and 15.8%/year for transitional aneurysms. Mangrum et al [12] also demonstrated substantially higher growth and rupture rates among fusiform/transitional aneurysms when compared to their dolichoectatic counterparts.…”