Background and purpose The Medina embolization device (MED) is a new flow disruption device combining the design of a detachable coil with an intrasaccular flow disrupter. Safety and short-term angiographic effectiveness of this device have recently been reported. However, long-term angiographic results are lacking. We report herein the 18 months’ angiographic outcome in patients treated for a wide-neck intracranial aneurysm with the MED.
Materials and methods Nineteen patients (17 female, mean age 50 years) with 20 wide-neck intracranial aneurysms (six ruptured; 14 unruptured) were treated by the MED between January 2015 and June 2016. Procedure-related complications were systematically recorded; discharge and 6–9 months' follow-up modified Rankin Scale scores were assessed. Angiographic mid-term and long-term follow-up were performed with a mean delay of 6.4±1.5 months (n=16 aneurysms) and 17.7±4.2 months (n=15 aneurysms), respectively. Occlusion rates were evaluated after the procedure and at the mid-term and long-term follow-up using the Roy-Raymond scale.
Results Embolization with the MED was feasible in all except two cases (2/20, 10%). One per-procedural perforation was recorded (1/20, 5%) and one MED deployment failed because of the aneurysm’s shape (1/20, 5%). Three cases of thromboembolic complications were observed (3/20, 15%). Only one thromboembolic complication was responsible for clinical sequelae. Grade A occlusion rate was 61% (11/18) after the procedure, 75% at 6 months' follow-up (12/16), and 80% (12/15) at long-term follow-up. Two cases (2/18, 11%) of recanalization at mid-term were documented angiographically. No recanalization occurred between the mid-term and long-term follow-up.
Conclusion MED is a hybrid embolization device, combining properties of a conventional coil with those of an intrasaccular flow disrupter. Our series focusing on long-term angiographic follow-up shows a satisfactory long-term occlusion rate. Larger series with longer angiographic follow-up times are warranted to confirm these preliminary results.
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During recent decades, new endovascular techniques have been developed to treat complex cerebral aneurysms. Indeed, standard coiling may be inappropriate to treat wide-necked bifurcation aneurysms without any adjunctive tools.1 Balloon remodeling technique and stent-assisted coiling are helpful in treating large-neck intracranial aneurysms by preventing coil loop protrusion into the parent artery,2 3 especially in sidewall aneurysms.4 5 Bifurcation aneurysms sometimes require more complex techniques such as Y-stenting or a kissing-balloon remodeling technique, which are associated with a higher procedure-related complication rate.6 7
The Medina embolization device (MED) (Covidien/eV3, Irvine, California, USA) is a hybrid device that combines the design of an endosaccular flow disrupter with a detachable coil. A limited number of series have reported the short-term angiographic follow-up with this device, with various results.8–11 However, data on long-term angiographic effectiveness of the MED are still lacking.
We report herein the 18 months' clinical and angiographic follow-up in 19 patients with 20 wide-necked intracranial aneurysms treated with the MED in a single center.
Materials and methods
Patient demographics and aneurysm characteristics
Twenty intracranial wide-necked (neck >4 mm and/or dome-to-neck ratio <2) aneurysms in 19 patients (mean age 53.7 years, range 38–72) were treated in our hospital between January 2015 and June 2016 by a MED (table 1). Large-necked aneurysms included in this series were those for which remodeling or stent-assisted coiling were considered difficult (recurrent branch to catheterize) or for which a significant risk of recanalization was suspected. In two patients (Nos 14 and 16) treatment by MED failed and they were finally treated by conventional coiling. Since current commercial MEDs have a size ranging from 6 to 9 mm for Framer devices and 5 to 8 mm for Filler devices, aneurysms in the same range of diameter were selected for treatment to ensure optimal results. Consequently, average aneurysm maximum diameter was 7.1±1.5 mm (range 5–10) with an average neck size of 4.3±1.0 mm (range 2.2–7.3). Large-necked aneurysms were screened to challenge the MED neck coverage abilities; the average dome-to-neck ratio was 1.2±0.3 (range 1.0–1.8). Most of the aneurysms were located on the anterior communicating artery (AComA) (7/20, 35%) (table 1). Most of the treated aneurysms were unruptured (14/20, 70%) but we also included ruptured aneurysms (6/20, 30%) treated at the acute phase (within 24 hours). As the procedure failed for patient No 14 (ruptured) and patient No 16 (unruptured), the final aneurysm population (n=18) comprised 5 ruptured and 13 unruptured aneurysms. In all cases, treatment modality and technique were chosen according to the aneurysm characteristics after a multidisciplinary discussion.
All procedures were performed via femoral access with the patient under general anesthesia. After initial diagnostic 3D rotational angiography, the aneurysm sizes (maximum diameter, neck size, dome-to-neck ratio) were measured and appropriate working positions selected. A triaxial system (6F long sheath (Neuron Max, Penumbra, Alameda, California, USA) and 6F distal access catheter) was used in all cases, to ensure satisfactory stability. The aneurysm sac was subsequently catheterized with a 0.021" microcatheter (Prowler Select Plus, Codman Neurovascular, Raynham, Massachusetts, USA). The size of the Framing MED chosen depended on the aneurysm size and shape, as described in a previous publication8 (table 2).
After deployment in the aneurysm, the resheathable MED could be repositioned until satisfactory coverage of the neck was obtained. Contrast material stagnation at the late venous phase on the angiogram was considered as a surrogate marker of satisfactory sealing of the aneurysm neck by the device. In most cases (15/18), only one Framing MED was necessary to obtain a basket, which was then filled with additional MED fillers or soft coils to prevent long-term retraction of the MED framing mesh. Remodeling balloons (Scepter C or XC, Microvention, Tustin, California, USA) were used in four cases (22%) to prevent MED loop protrusion into the parent artery. In one case (6%), bail-out stenting (BB Leo, Balt Montmorency, France) was performed because patency of the parent artery was compromised by the device. To prevent clot formation during the procedure, unruptured aneurysms were treated under full IV anticoagulation (bolus of 50 IU/kg, then prolonged throughout the procedure targeting an activated clotting time of between two- and threefold the baseline value). In ruptured aneurysms, IV heparin was started only after deployment of the first MED.
One patient (No 8), was re-treated at 6 months with a flow-diverter stent (FDS, 6.5 mm, Derivo, Acandis, Pforzheim, Germany) because of an early major recurrence, probably due to discrepancy between the aneurysm diameter (10 mm) and the MED size (9 mm, the largest size available).
Clinical and angiographic follow-up
Clinical outcome was evaluated using the modified Rankin scale (mRS) at discharge and mid-term (average 10±8 months). Angiographic mid-term follow-up (6 months) was available in 16/18 aneurysms (89%). Long-term angiographic follow-up (18 months) was available in 15/18 aneurysms (83%). No angiographic follow-up was available for patient No 3 (from another country) or for patient No 18 (lost to the follow-up). The angiographic occlusion rate was evaluated using the Roy-Raymond scale12 at the end of the procedure, at mid-term (average 6.4±1.5 months), and long-term follow-up (average 17.7±4.2 months) either on DSA (12/15, 80% of late angiographic follow-up) and/or magnetic resonance angiography (MRA) (3/15, 20% of late angiographic follow-up) (table 3).
The MED, at the time of the study, had the CE mark and was available for routine clinical use. This series is a local single-centre registry. Neither approval of the institutional review board nor patient informed consent is required by the ethics committee of our institution for retrospective analyses of patients’ records and imaging data.
Embolization with the MED was feasible in all except two cases (patients 14 and 16) (10%). One aneurysm perforation occurred in the treatment of an unruptured AComA aneurysm during deployment of the first Medina device (patient No 16). The acute bleeding was stopped by manual compression of the cervical internal carotid artery (ICA), and the aneurysm was quickly excluded by regular coiling. After appropriate intensive care management, the patient was discharged at day 9 with a modified Rankin Scale (mRS) score of 0. In patient No 14, the MED could not be deployed satisfactorily owing to the heart shape of the aneurysmal sac; the patient thus underwent regular coiling.
In three cases (3/20; 15%) thromboembolic complication was recorded. After the procedure, patient No 14 had a right superficial infarct with 4/5 motor deficit affecting the left arm. At 24 months' follow-up, this patient’s mRS score was 0.
The second thromboembolic complication (patient No 4) occurred during the treatment of a ruptured AComA aneurysm and consisted of a delayed clot formation (24 hours) at the aneurysm neck (confirmed by DSA), leading to a temporary slow down of the blood flow in the anterior cerebral artery. Clinically, the complication was disclosed by a hemiparesis that resolved after IV injection of aspirin (250 mg), with no clinical sequelae.
The last patient (No 18) presented a dysplastic AComA aneurysm involving the overall AcomA with a very large neck (dome-to-neck ratio=1). The strategy chosen was to occlude both the aneurysm and the AcomA. Thromboembolic complication occurred during the procedure, leading to occlusion of the right A1–A2 junction. Bail-out stenting was performed with a BB Leo stent (Balt). Satisfactory reopening of the right anterior cerebral artery was obtained. However, the patient awoke with a left hemiparesis and MRI showed an acute ischemic infarct of the right caudate nucleus. At discharge, after 21 days of intensive care, patient still had frontal syndrome and left hemiparesis. Unfortunately, no follow-up is available for this patient (lost to the follow-up). Average procedure time, defined as the delay between the positioning of the microcatheter in the aneurysm sac and the final control DSA, was 37.2±15.4 min. Neither inopportune release of the device nor difficulties in detaching the MED were observed.
Immediate, mid-term, and long term follow-up angiographic results
Complete aneurysm occlusion (Roy-Raymond (RR) grade A) was observed at the end of the procedure in 11/18 aneurysms (61%) (figure 1); in 5/18 aneurysms (28%) a residual aneurysm (grade C) was seen immediately on the final DSA run. Angiographic mid-term follow-up (mean delay 6.4 months) was available for 16 aneurysms (patients 3 and 18 were lost to the follow-up). Complete occlusion (RR grade A) was seen in 12/16 aneurysms (75%) (figure 1). Among the four cases with no complete occlusion at 6 months, two recanalizations (2/16; 12.5%; patients 4 and 8) were observed and two stable RR grade B remnants were seen (2/16; 12.5%; patients 17 and 19) (figure 2). Patient No 4 had a ruptured aneurysm with postprocedure RR grade A occlusion, which evolved to RR grade C (2 mm recanalization) at mid-term angiographic follow-up. The recanalization spontaneously improved at long-term control to grade B (12- and 22-month angiograms) and no additional treatment was performed. On the other hand, re-treatment with a 6.5 mm Derivo FDS (Acandis, Pforzheim, DE) was necessary for patient No 8 because the initial grade C remnant worsened at the mid-term angiographic control.
Long-term follow-up (mean delay 17.7±4.2 months) was available in 15 aneurysms. Twelve of the 15 aneurysms (80%) had complete occlusion (RR grade A) at long-term follow-up. Only three aneurysms (20%) (in patient 4, 17, and 19) had incomplete occlusion at long-term follow-up (stable RR grade B remnant). It is noteworthy that no recanalization occurred between mid-term and long-term angiographic control.
Short-term (ie, ≤6 months) angiographic outcome of intracranial aneurysms treated with MED has already been reported in few case series, with various occlusion rates obtained.8–11 Our team has recently reported results at short-term angiographic follow-up with the MED for embolization of intracranial aneurysms in 12 patients, with promising results (83% of complete RR grade A occlusion at 6 months’ follow-up).8 In this study, we sought to evaluate the long-term (ie, 18 months) angiographic outcome of 18 intracranial aneurysms in 17 patients treated with MED. Complete occlusion (RR grade A) rate was 80% at 18 months in our series. Two early recanalizations occurred between 0 and 6 months, but no recurrence was seen at late angiographic follow-up (ie, from 6 to 18 months).
Few published data are available on long-term angiographic outcome in patients treated by MED for intracranial aneurysms. Indeed, only immediate postprocedure8–11 or short-term (ie, 6 months)8 9 11 follow-ups have been reported. In the series of Aguilar Perez et al,9 long-term angiographic outcome could not be reliably evaluated since most of the patients were re-treated early with additional devices (in most cases by FDS). Satisfactory (ie, RR grade A or B) angiographic occlusion rates of 36% to 83% at 6 months with the MED have been reported8–10 Some factors may explain our promising results for long-term angiographic outcome with MED.
First, sizing of the MED device, especially for the first Framer MED, is of tremendous importance. The smallest available framing MED has 6 mm diameter loops, limiting its deployment in aneurysms smaller than 6 mm. According to our experience, the first Framing MED should be positioned so that it fully opens and the petals completely cover the aneurysm neck. The first MED by itself allows disruption of the flow and can be sufficient to cure the aneurysm (patient No 6: ICA terminus and carotid-ophthalmic aneurysms respectively treated with one MED Filler and one MED Framer alone). However, if the first MED does not fully cover the neck or is undersized (patient No 8), there is a risk of recanalization. Indeed, patient No 8, for instance, was treated with an undersized 9 mm Framer MED for a 10 mm diameter spherical aneurysm. Additional treatment with a Derivo flow-diverter stent was necessary at 6 months because of an RR grade C recanalization. Aguilar Perez et al 9 voluntarily undersized their MED by 1 mm for aneurysms smaller than 9 mm, to limit per-procedural rupture risk. This voluntary undersizing might partially explain the lower occlusion rate obtained in their series. Indeed, only 1/15 (7%) patients had a complete immediate occlusion and 4/11 (36%) at follow-up (mean 2 months).
Second, neck coverage is also a major goal that should be reached for a satisfactory aneurysm occlusion. It has been proven, on a flow model, that flow reduction is seen only when the neck sealing is obtained with the petals covering the neck.13 Additionally, we can extrapolate the pathological results obtained on animal models with FDS,14 and state that the petals’ mesh may act as a scaffold for endothelial regrowth. In our study, we used late contrast media stagnation (ie, contrast media stagnation at the venous phase) in the aneurysm sac on DSA as a surrogate marker of satisfactory neck coverage. In our early experience, flat-panel CT volume acquisition seems unreliable for evaluating aneurysm neck coverage since the radiopaque core wire of the device is responsible for streaking artifacts that hamper visualization of the less radiopaque petals of the MED.
Third, we deployed, in our series, additional MED Fillers or regular coils in order to stabilize the configuration of the Framing MED device, prevent late compaction, and obtain satisfactory neck sealing.
As mentioned above, neck sealing was assessed by contrast media stagnation in the aneurysm at the late venous phase on DSA. When this stagnation was not obtained with the Framer MED alone, other devices (Medina Fillers or conventional soft coils) were used until satisfactory stagnation was visualized.
The additional use of coils until complete neck sealing could be the main reason why we report a higher immediate and delayed occlusion rate than the one reported by Aguilar Perez et al.9 Indeed, to assess the MED flow-disrupting effect on its own, no additional coiling was performed in their 15 consecutive unruptured aneurysms. Finally, selection of aneurysms with a proper shape is also very important when using MED. In our series, we selected mainly patients with ovoid and spherical aneurysms because of the MED’s ovoid shape when fully deployed. This limitation to a wide use of MED has been underlined by Aguilar Perez et al.9
We attempted to treat a bilobulated ICA aneurysm (patient No 15) and failed to find a stable positioning of the MED. Eventually, the aneurysm was successfully treated by conventional coiling. However, MED may be suitable for non-spherical/ovoid aneurysms. Indeed, we treated a bilobulated aneurysm (patient No 16) and obtained contrast media stagnation in the second lobe on immediate postprocedure DSA, and long-term exclusion grade A at 12 months' DSA. This example illustrates the fact that appropriate neck sealing without complete filling of the aneurysm may be sufficient to obtain long-term occlusion. Although the MED is designed preferentially to treat spherical and ovoid aneurysms, it also allows for the treatment of complex-shape aneurysms, as long as the neck is well covered.
Some authors have proposed the use of additional tools with the MED for the treatment of intracranial aneurysms. Aguilar Perez et al 9 completed most of their embolizations with additional tools such as balloons, FDS or pCONus15 devices.
FDS are compatible with the MED, but we only once used a FDS to treat one case of delayed recanalization (patient No 8). Systematic use of FDS with the MED would limit their indication to unruptured aneurysms, since dual antiplatelet therapy is not recommended in ruptured aneurysms (table 2).
In our experience, no adjunctive tools such as pCONus were necessary, thanks to the wide coverage of the Medina device, but these two devices can be used together to treat intracranial aneurysms, as reported by Auguilar Perez et al.9 In our series, without any additional FDS or pCONus, the complete occlusion rate was 61% (11/18) in the postprocedural angiogram and 75% (12/16) at mid-term angiographic follow-up (mean 6.4 months). The ‘satisfactory’ occlusion (grade A or B) rate was 100% (15/15) at 18 months, with only one re-treatment.
Additional tools (non-detachable balloon, regular stent) were used to assist coiling in wide-necked aneurysms in only five cases (31%; four balloons and one stent). In one case, the stent (patient No 18) was used in a bail-out fashion, owing to MED protrusion into the parent artery. The complication rate reported with MED ranges from 0% to 23% in the literature.9–11 In our series, we experienced three thromboembolic complications (3/20, 15%) and one perforation (5%). The periprocedural perforation occurred in a 5 mm spherical AcomA unruptured aneurysm (patient No 16). The perforation was probably due to the use of an oversized 6 mm Medina Framer (smallest diameter available at that time), which was responsible for excessive constraint against the aneurysm wall. After conventional coiling, the patient was managed in a neurointensive care unit. He was eventually discharged on day 9 with an mRS score of 0. Only one of the thromboembolic complications (5% of the overall population) led to clinical sequelae (patient No 18). This patient experienced a frontal syndrome associated with a hemiparesis at discharge owing to occlusion of the artery of Heubner. Unfortunately, no follow-up was available for this patient. Recently, Turk et al 11 have shown the periprocedural safety of the MED and satisfactory immediate angiographic results for the treatment of unruptured intracranial aneurysms. Aguilar Perez et al 9 also reported a safe experience with MED, with only 3/15 reported complications, not related to the MED itself, and with a low clinical significance for patients.
Limitations of the study
The main limitation of our study is its monocentric and retrospective design, with a small number of patients. Additionally, no randomization was performed to compare the results of the MED with the results of regular coiling. Finally, because additional MED Filler and soft coils were inserted inside the first MED Framer, this limits analysis of the ability of the MED Framer to cure the aneurysm by itself.
MED is a hybrid embolization device, which associates the properties of a conventional coil with those of an intrasaccular flow disrupter. Our series focusing on long-term angiographic follow-up shows a satisfactory long-term occlusion rate. Larger series with longer angiographic follow-up are warranted to confirm these preliminary results.
Contributors FC and N-AS contributed to the design and conception of the work. FC, N-AS, CB, SVP, BM, and MD contributed to the acquisition of data for the work. IH, FC, N-AS, and ES contributed to the analysis and interpretation of data for the work. All authors contributed to drafting or revising the work, approved the final version to be published, and are accountable for all aspects of the work.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests FC is a consultant for Medtronic (paid lectures), Balt (paid lectures), Guerbet (paid lecture), and Codman Neurovascular (study core laboratory). N-AS is a consultant for Medtronic, Balt Extrusion, and Microvention (fee or honorarium) and has stock/stock options for Medina.
Patient consent Not required.
Ethics approval Pitié-Salpêtrière Hospital ethic committee.
Provenance and peer review Not commissioned; externally peer reviewed.
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