Plasticity of the adult circle of Willis in response to flow diversion stents.

Background: We present five patients with remodeling of the adult circle of Willis in response to flow diverter stents (FDSs) at the anterior communicating artery (AComA) and the posterior communicating artery (PComA). The observed changes provide a paradigm of how flow change can institute anatomic changes in the adult circle of Willis vasculature. Case Description: In the first two cases, after placement of the FDS covering the AComA, there was an increase in size and flow of the contralateral A1-anterior cerebral artery which had previously been hypoplastic. In one of the cases, this led to the filling of the aneurysm and required placement of coils within the lesion which was curative. In case three, the FDS effect led to asymptomatic occlusion of the PComA and associated aneurysm without change of the ipsilateral P1-segement of posterior-cerebral-artery (P1-PCA) caliber. In the fourth case, the FDS covering an aneurysm with a fetal PCA arising from its neck resulted in significant reduction of the aneurysm size, persistent flow and caliber of the fetal PCA, and the hypoplastic ipsilateral P1-PCA. Finally, in the fifth case, after FDS occlusion of the PComA and aneurysm there was increasement in diameter of the ipsilateral P1-PCA that was previously hypoplastic. Conclusion: The use of FDS can affect vessels covered by the device and other arteries of the circle of Willis adjacent to the FDS. The phenomena illustrated in the hypoplastic branches appear to be a compensatory response to the hemodynamic changes induced by the divertor and to the altered flow in the circle of Willis.

Multimodal cerebral arteriovenous malformation treatment: a 12-year experience and comparison of key outcomes to ARUBA.

OBJECTIVE: Curative treatment of unruptured brain arteriovenous malformations (AVMs) remains controversial after the only randomized controlled trial, A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA), was halted prematurely because interim analysis revealed superiority of the medical management group. In contrast, meta-analyses of retrospective cohorts suggest that intervention is much safer than was found in ARUBA. METHODS: The authors retrospectively analyzed 318 consecutive adult patients with brain AVMs treated at their institution with embolization, surgery, and/or proton beam radiosurgery. Analysis was performed in 142 ARUBA-eligible patients (baseline modified Rankin Scale [mRS] score 0-1, no history of hemorrhage), and results were compared to primary and secondary outcomes from ARUBA, as well as to natural history cohorts. RESULTS: The annualized stroke rate (hemorrhagic or ischemic) in this cohort was 1.8%, 4.9% in the first 12 months and 0.8% after the first 12 months, which was lower than in natural history studies and the ARUBA medical management arm (p = 0.001). The primary ARUBA endpoint of symptomatic stroke was reached in 13 patients (9.2%), which compares favorably to the ARUBA intervention arm (39.6%, p = 0.0001) and is similar to the ARUBA medical management arm (9.2%, p = 1.0). The secondary ARUBA endpoint (mRS score ≥ 2 at 5 years of follow-up) was reached in 14.3% of patients, compared to 40.5% in the ARUBA intervention arm (p = 0.002) and 16.7% in the ARUBA medical management arm (p = 0.6). CONCLUSIONS: This multimodal approach to the selection and treatment of patients with brain AVMs yields good clinical outcomes with key safety endpoints (stroke, death, and mRS score 0-1) better than the ARUBA intervention arm and similar to the ARUBA medical arm at 5 years of follow-up. Results compare favorably to natural history cohorts at longer follow-up times. This suggests that tertiary care centers with integrated programs, expertise in patient selection, and individualized treatment approaches may allow for better clinical outcomes than reported in ARUBA. It supports current registry studies and merits consideration of future randomized controlled trials in patients with brain AVMs.

Impact of Coil Packing Density and Coiling Technique on Occlusion Rates for Aneurysms Treated with Stent-Assisted Coil Embolization.

BACKGROUND AND OBJECTIVE: Stent-assisted coil embolization is an established endovascular technique for wide-necked intracranial aneurysms. Although recanalization after coil embolization is reduced with the use of a stent, the impact of aneurysm packing density is less clear in stent-coiled aneurysms. The purpose of the present study was to assess packing density in stent-coiled aneurysms and evaluate its effect on recanalization and retreatment. METHODS: A retrospective analysis of consecutive aneurysms treated with stent-assisted coiling was performed at 2 academic institutions between 2007 and 2015. Aneurysm occlusion was assessed using digital subtraction angiography. Packing density was calculated using the AngioCalc app. RESULTS: Two hundred fifty-three aneurysms were identified (median age, 59 years). The median packing density was 35.3%. At last follow-up, 72.7% of aneurysms were completely obliterated and 19.4% had a neck remnant. Complete occlusion was associated with smaller aneurysms and coiling through stent interstices. A higher packing density was associated with increased rate of complete occlusion when analyzed as continuous variable. After adjustment for confounding variables, packing density was no longer predictive of complete occlusion (odds ratio = 1.018, P = 0.122). Similarly, there was no significant association between aneurysm occlusion, retreatment, and packing density when assessed by categories of high (>22%), moderate (12%-22%), and low (<12%) packing density. CONCLUSIONS: Aneurysm size remains the most important predictor of aneurysm recanalization and retreatment after stent-assisted coiling. Although higher packing densities were associated with increased rates of aneurysm occlusion in unadjusted statistical comparisons, this finding was no longer significant after adjusting for confounders.