Flow diversion treatment of complex bifurcation aneurysms beyond the circle of Willis: complications, aneurysm sac occlusion, reabsorption, recurrence, and jailed branch modification at follow-up

Abstract

OBJECTIVEThe purpose of this study is to present the authors’ medium-term results, with special emphasis on complications, occlusion rate of the aneurysm sac (digital subtraction angiography [DSA] and MRI), and the fate of cortical branches and perforating arteries covered (“jailed”) by the flow diverter (FD) stent.METHODSBetween January 2010 and September 2017, 29 patients (14 female) with 30 aneurysms were treated with an FD stent. Twenty-one aneurysms were at the middle cerebral artery bifurcation, 8 were in the anterior communicating artery region, and 1 was a pericallosal artery bifurcation. Thirty-five cortical branches were covered. A single FD stent was used in all patients. Symptomatic and asymptomatic periprocedural and delayed complications were reported. DSA and MRI controls were analyzed to evaluate modification of the aneurysm sac and jailed branches.RESULTSPermanent morbidity was 3.4% (1/29), due to a jailed branch occlusion, with a modified Rankin Scale (mRS) score of 2 at the last follow-up. Mortality and permanent complication with poor prognosis (mRS score > 2) rates were 0%. The mean follow-up time for DSA and MRI (mean ± SD) was 21 ± 14.5 months (range 3–66 months) and 19 ± 16 months (range 3–41 months), respectively. The mean time to aneurysm sac occlusion (available for 24 patients), including stable remodeling, was 11.8 ± 6 months (median 13, range 3–27 months). The overall occlusion rate was 82.1% (23/28), and it was 91.7% (22/24) in the group of patients with at least 2 DSA control sequences. One recanalization occurred at 41 months posttreatment. At the time of publication, at the latest follow-up, 7 (20%) of 35 covered branches were occluded, 18 (51.4%) showed a decreased caliber, and the remaining 10 (28.5%) were unchanged. MRI T2-weighted sequences showed complete sac reabsorption in 7/29 aneurysms (24.1%), and the remaining lesions were either smaller (55.2%) or unchanged (17.2%). MRI revealed asymptomatic and symptomatic ischemic events in perforator territories in 7/28 (25%) and 4/28 (14.3%) patients, respectively, which were reversible within 24 hours.CONCLUSIONSFlow diversion of bifurcation aneurysms is feasible, with low rates of permanent morbidity and mortality and high occlusion rates; however, recurrence may occur. Caliber reduction and asymptomatic occlusion of covered cortical branches as well as silent perforator stroke are common. Ischemic complications may occur with no identified predictable factors. MRI controls should be required in all patients to evaluate silent ischemic lesions and aneurysm sac reabsorption over time.

Expanding Indications for Flow Diverters: Distal Aneurysms, Bifurcation Aneurysms, Small Aneurysms, Previously Coiled Aneurysms and Clipped Aneurysms, and Carotid Cavernous Fistulas

“…Considering series with mixed caseload, reported acute or subacute thromboembolic events rate varies from 3.7% to 24%, and mostly transient or asymptomatic. 11,16-19 In the series by Michelozzi et al, 19 periprocedural thromboembolic complications occurred in 13.8% of patients; however, the occlusion rate was high and improved with time (82.1% at 3-6 mo, rising to 91.7% at late follow-up). In a series of 46 distal aneurysms, the occlusion rate was 78.2% with no differences between saccular and fusiform aneurysms; thromboembolic events occurred in 17.4% of patients, and they were more common in saccular aneurysms.…”

Preliminary in vitro angiographic comparison of the flow diversion behavior of Evolve and Pipeline devices

“…Flow diverters have been used successfully to treat patients with aneurysms for more than a decade 5–7. The success of flow diversion in larger aneurysms has led to an expanded indication to treat small and medium-sized, side wall aneurysms 8–12. Since the SILK (Balt Extrusion, France) and Pipeline (Covidien/Medtronic, USA) devices received CE Mark a decade or more ago, multiple devices have subsequently been developed and commercialized in the EU, including Surpass Streamline (Stryker Neurovascular, USA), FRED (Microvention/Terumo, USA), p64 (phenox, Germany), Derivo (Acandis, Germany), Bravo (Cerenovus, USA), and Tubridge (Microport, China).…”

Complex Wide-necked and Lobulated Aneurysm of the Middle Cerebral Artery Bifurcation

“…Flow diversion is being increasingly used to treat bifurcation aneurysms. In cases of MCA bifurcation aneurysms, FD treatment is feasible with good angiographic results and acceptable complication rates; however, compared to the results of other endovascular techniques and to surgery, total occlusion seems to be less frequent [ 3 , 19 , 20 ]. Most of these new tools available on the market target the temporary or permanent reconstruction of the aneurysmal neck [ 21 , 22 ], the parent artery or both but in certain scenarios, alternative or combination techniques are mandatory to secure the patency of the incorporated branches and deal with the troublesome anatomy.…”

“…These devices share the common feature of providing extra coverage at the aneurysm neck to prevent coil prolapse into the parent vessel. Endoluminal flow diversion (FD) appears to be a straightforward solution for complex and unfavorable anatomy with good angiographic results and acceptable complication rates; however, the fate of the covered branches and the delayed aneurysm occlusion are still a major concern [ 3 ].…”