Stent-assisted coiling technology has been widely used in the treatment of ++intracranial aneurysm++s.
Stent-assisted coiling achieved better complete occlusion rates of aneurysms at 6 months or later after the procedure compared to balloon assisted coiling, without being associated with a higher risk of intraprocedural complications and retreatment 1).
Stent-assisted coiling (SAC) and balloon-assisted coiling (BAC) were alternative techniques developed to deal with complex aneurysms, but studies have shown their less than expected efficacy given their high rate of recanalization 2) 3) 4) 5).
Stent assisted coiling of unruptured wide necked intracranial aneurysms require antiplatelets to prevent stent thrombosis. The effect of the loading dose of antiplatelets prior to the stent coiling procedure in an unsecured wide necked ruptured intracranial aneurysm is not known.
In the series of Lodi et al carefully selected patients, therapeutic dual antiplatelet loading prior to stent assisted coiling of ruptured wide necked intracranial aneurysm was not associated with increased bleeding complications. However, thromboembolic events remain the main challenge. Further study is required to confirm the safety of antiplatelet loading in stent assisted ruptured intracranial aneurysm coiling 6).
Between September 2012 and June 2016, a total of 463 intracranial aneurysms were treated by stent-assisted coil embolization. Of these, 132 small saccular aneurysms displayed saccular filling with contrast medium in the immediate aftermath of coiling. Progressive thrombosis was defined as complete aneurysmal occlusion at the 6‑month follow-up point. Rates of progressive occlusion and factors predisposing to this were analyzed via binary logistic regression.
In 101 (76.5%) of the 132 intracranial aneurysms, complete occlusion was observed in follow-up imaging studies at 6 months. Binary logistic regression analysis indicated that progressive occlusion was linked to smaller neck diameter (odds ratio [OR] = 1.533; p = 0.003), hyperlipidemia (OR = 3.329; p = 0.036) and stent type (p = 0.031). The LVIS stent is especially susceptible to progressive thrombosis, more so than Neuroform (OR = 0.098; p = 0.008) or Enterprise (OR = 0.317; p = 0.098) stents. In 57 instances of progressive thrombosis, followed for ≥12 months (mean 25.0 ± 10.7 months), 56 (98.2%) were stable, with minor recanalization noted once (1.8%) and no major recanalization.
Aneurysms associated with smaller diameter necks, hyperlipidemic states and LVIS stent deployment may be inclined to possible thrombosis, if occlusion immediately after stent-assisted coil embolization is incomplete. In such instances, excellent long-term durability is anticipated 7).
Over a 10-year period, a single surgeon treated 486 aneurysms with SAE in which open-cell Neuroform or closed-cell Enterprise stents were used. Single stents were used in 386 cases, overlapping stents were deployed in 80 cases, and Y-configuration stents were used in the remaining 20 cases. All neurological complications, which included transient deficits, were analyzed; disabling strokes and death were considered major complications. The chi-square test and multivariate logistic regression were used to evaluate the influence of aneurysm size and morphology, aneurysm location, stent selection, and stent configuration on complication rates.
There were 7 deaths (1.4%), 9 major strokes (1.9%), and 18 minor neurological complications (3.7%). For all complications, multivariate analysis revealed that large aneurysm size (10-25 mm; p = 0.01), giant aneurysm size (> 25 mm; p = 0.04), fusiform aneurysm morphology (p = 0.03), and using a Y-configuration stent (p = 0.048) were independent risk factors. For the major complications, independent risk factors included an aneurysm in the posterior circulation (p = 0.02), using an overlapping stent configuration (p = 0.03), and using a Y-configuration stent (p < 0.01). In this series, SAE for cerebral aneurysm treatment carried an acceptable complication rate. With continued innovations in techniques and devices and with increased experience, the complication rates associated with SAE may be even lower in the future 8).
In 72 patients included in this study, periprocedural complications occurred in 14 (19.4%), including asymptomatic complications in 4 (5.6%) and symptomatic complications in 10 (13.9%); there were symptomatic thromboembolic complications in 5 patients (6.9%), and symptomatic hemorrhagic complications in 5 (6.9%). The authors observed no subacute or delayed thromboembolic complications during the follow-up period of 18.8 months. Use of external ventricular drainage (EVD) (OR 1.413, 95% CI 0.088-2.173; p = 0.046) was the only independent risk factor for periprocedural complications on multivariate logistic regression analysis.
The periprocedural complication rate during SAC was 19.4% among 72 patients. Because of the high complication rate, microsurgical clipping or endovascular treatment with another technique (multiple-microcatheter or balloon-assisted technique) may be a more appropriate option for first-line treatment than SAC, especially in patients requiring EVD 9).
There are several complications associated with Stent-assisted Coil Embolization (SACE) in cerebral aneurysm treatments, due to damaging operations by surgeons and undesirable mechanical properties of stents. Therefore, it is necessary to develop an in vitro simulator that provides both training and research for evaluating the mechanical properties of stents.
A new in vitro simulator for three-dimensional digital subtraction angiography was constructed, followed by aneurysm models fabricated with new materials. Next, this platform was used to provide training and to conduct photoelastic stress analysis to evaluate the SACE technique.
The average interaction stress increasingly varied for the two different stents. Improvements for the Maximum-Likelihood Expectation-Maximization method were developed to reconstruct cross-sections with both thickness and stress information.
The technique presented can improve a surgeon's skills and quantify the performance of stents to improve mechanical design and classification. This method can contribute to three-dimensional stress and volume variation evaluation and assess a surgeon's skills 10).