Abstract
Background
Flow diversion (FD) has emerged as an effective treatment option for intracranial aneurysms. However, there is limited evidence regarding its safety and efficacy specifically for distal and small‐artery aneurysms of the posterior circulation. This study aimed to investigate the outcomes of FD for aneurysms arising from the posterior inferior cerebellar artery, anterior inferior cerebellar artery, superior cerebellar artery, and the P2 and P3 segments of the posterior cerebral artery.
Methods
This is a subanalysis of the Post‐FD (Posterior Circulation Aneurysms Treated With Flow Diversion) registry, highlighting distal aneurysms in the posterior inferior cerebellar artery, anterior inferior cerebellar artery, superior cerebellar artery, and the P2 and P3 segments of the posterior cerebral artery treated with FD. Aneurysm characteristics and patient outcomes were described for the total series, and a more focused analysis comparing fusiform/dissecting versus saccular aneurysms was performed. The primary treatment outcome was complete aneurysm occlusion (Raymond–Roy class 1). Primary safety outcome was major ischemic/hemorrhagic stroke following FD. Secondary outcomes included functional outcome, aneurysm retreatment, and in‐stent stenosis.
Results
Overall, 36 patients with 36 aneurysms were treated with FD, with a median age of 60.0 years (interquartile range [IQR], 52.8—65.3 years). Of those, 13 were fusiform/dissecting, while 23 were saccular aneurysms. Complete occlusion was achieved in 78.1% for all aneurysms at a median follow‐up of 14.0 months (IQR, 9.3–48.6 months). There was a nonsignificant trend in rates of complete occlusion between fusiform/dissecting (91.7%) and saccular aneurysms (70%; P = 0.151). Major stroke was reported in 2 cases (5.6%) and in‐stent stenosis in 4 (11.1%), and retreatment was required for 4 aneurysms (11.4%) There was no difference in rates of major stroke, in‐stent stenosis, or retreatment between fusiform/dissecting and saccular aneurysms.
Conclusion
This study suggests the safety and feasibility of FD for distal aneurysms of the posterior circulation, particularly fusiform/dissecting aneurysms. Further larger‐scale studies are warranted to confirm these findings.
Keywords: aneurysms, distal branches, flow diversion, posterior circulation
Nonstandard Abbreviations and Acronyms
- FD
flow diversion
- PCA
posterior cerebral artery
- PED
Pipeline embolization device
- PICA
posterior inferior cerebellar artery
- Post‐FD
Posterior Circulation Aneurysms Treated With Flow Diversion
- SCA
superior cerebellar artery
Clinical Perspective
What Is New?
This is the largest study that reported the outcomes of flow diversion for distal aneurysms of the posterior circulation.
Flow diversion was efficacious and safe for distal aneurysms of the posterior circulation.
Particularly, fusiform aneurysms may have a higher rate of occlusion and low rates of stroke complications following flow diversion.
What Are the Clinical Implications?
The results from this study suggest the safety and feasibility of flow diversion for distal aneurysms of the posterior circulation, particularly fusiform/dissecting aneurysms.
Posterior circulation aneurysms pose a significant challenge in neurovascular practice due to their complex anatomy, high rupture rates, and high risk for devastating outcomes. 1 , 2 Among the subtypes of posterior circulation aneurysms, those located in distal locations such as the posterior inferior cerebellar artery (PICA), anterior inferior cerebellar artery, superior cerebellar artery (SCA), and the P2 and P3 segments of the posterior cerebral artery (PCA) are infrequently encountered. 3 Notably, aneurysms in these locations represent a distinct subset 3 due to the small diameter of the parent vessels and to their relationship with vital perforator vessels that supply critical brain regions, such as the brain stem and cerebellum. 4 , 5 , 6
Traditional treatment modalities for posterior circulation aneurysms, such as microsurgical clipping and endovascular coiling, may be challenging for these distal aneurysms due to their deep‐seated location, intricate angioarchitecture, and the inherent risk of vessel injury. In recent years, however, flow diversion (FD) has emerged as a promising therapeutic option for intracranial aneurysms. Despite the increasing adoption of FD in the treatment of posterior circulation, there remains a paucity of comprehensive studies specifically focusing on clinical outcomes after the management of aneurysms of the PICA, anterior inferior cerebellar artery, SCA, and the P2 and P3 segments of the PCA. 7
Therefore, the primary objective of this multicenter collaborative study is to investigate the safety and efficacy of FD for distal aneurysms (PICA, anterior inferior cerebellar artery, SCA, and the P2 and P3 segments of PCA) of the posterior circulation. This study also evaluates the differences in angiographic and clinical outcomes between fusiform/dissecting versus saccular aneurysms.
Methods
Study Cohort and Patient Selection
This is a subanalysis of the multicentric observational North American registry Post‐FD (Posterior Circulation Aneurysms Treated With FD), which included patients treated with FD for posterior circulation aneurysms between May 2014 and November 2022. This study included patients who had saccular, fusiform, or dissecting aneurysms (ruptured or unruptured) in distal locations (PICA, anterior inferior cerebellar artery, SCA, and the P2 and P3 segments of the PCA). All FD types were included. Device selection was left to the discretion of the operator, which was based on the clinical characteristics of the patient and aneurysm, local availability, and operational experience with the device. This study was approved by the local institutional review boards from all the enrolled centers. Informed consent was waived due to the observational nature of the study. Data are available upon reasonable request to the corresponding author.
FD Devices
The FD included in this study were all 3 generations of the Pipeline embolization device (PED, PED Flex, and PED Shield; Medtronic, Minneapolis, MN), flow redirection endoluminal device (Microvention, Aliso Viejo, CA), Silk (Silk Vista and Silk Vista Baby; Balt Extrusion, Montmorency, France), and Surpass Streamline (Stryker, Kalamazoo, MI). Description of the types and characteristics of FD used in this study are in Supplementary Text 1. The median diameter and length among each of the used devices ranged between 2.3 to 3.1 mm and 13 to 20 mm, respectively (Table S1).
The procedure was conducted following the protocols outlined in existing literature, although minor variations might have occurred on the basis of the specific treating center, clinician, and device availability. 8 Furthermore, the pre‐ and postprocedural antiplatelet regimen and scheduling of follow‐up was performed as per each center's protocol.
Clinical, Radiographic, and Treatment Characteristics
The following information was collected using a standardized data sheet: patient demographics (age, sex, smoking status, comorbidities, presentation, Hunt and Hess score, modified Rankin Scale score, and use of antiplatelets), aneurysm characteristics (laterality, size [largest dimension], dome height, dome width, location, aneurysm rupture status, branch arising from aneurysm dome, and prior treatment), procedural details (procedure date, type of access, number of flow diverters and their measurements, adjunctive coil placement, and post‐treatment antiplatelet therapy).
Outcomes and Complications
The primary effectiveness outcome was complete occlusion (class 1) on the Raymond–Roy occlusion classification at last imaging follow‐up. 9 The angiographic outcome was assessed using digital subtraction angiography, magnetic resonance angiography, or computed tomography angiography. Also, complete occlusion using the O'Kelly Marotta scale class D 10 on digital subtraction angiography was reported. Functional outcome was assessed using the modified Rankin Scale at the last follow‐up. The primary safety outcome was major stroke (ischemic/hemorrhagic) in the area supplied by the target vessel that resulted in an increase of at least 4 points on the National Institutes of Health Stroke Scale score within a 1‐year time frame.
Additionally, we collected information related to technical complications following FD deployment, such as fishmouthing (ie, a change in device configuration, resulting in reduction in lumen without intimal hyperplasia), and the presence of in‐stent stenosis at radiographic follow‐up. Finally, if retreatment was performed, details related to the date and technique were collected.
Statistical Analysis
Categorical variables are presented as frequencies with percentages and compared using the χ2 test or the Fisher exact test, as appropriate. Continuous variables were presented as median (interquartile range [IQR]) and compared using the Mann–Whitney U test. A mixed‐effect ordinal regression model was used to compare ordinal outcomes while adjusting for different center practices. Results were deemed statistically significant if they had a P value of ≤0.05. Statistical analysis was performed with using R software version 4.0.2 (R Foundation for Statistical Computing, Vienna, Austria).
Results
Patient and Aneurysm Characteristics
A total of 36 patients and aneurysms (median age, 60 years [IQR, 53—65 years]; male‐to‐female ratio, 1:1.8) underwent FD implantation for distal aneurysms of the posterior circulation. Most patients (24/36, 66.7%) presented with unruptured aneurysms, and all patients had modified Rankin Scale scores of 0 to 2 at the time of presentation. The most common location was in the PICA (21/36, 58.3%), followed by SCA (5/36, 13.9%) and P2 segment of the PCA (5/36, 13.9%). Of these aneurysms, 13 were fusiform/dissecting, while 23 were saccular. The majority were sidewall aneurysms (32/33, 97.0%). The median size, dome height, and dome width were 4.8, 4.0, and 3.9 mm, respectively. Comparison between fusiform/dissecting and saccular aneurysms revealed similar patient and aneurysm characteristics except for higher rates of rupture, which occurred more frequently in fusiform/dissecting aneurysms compared with saccular (61.5% versus 17.4%; P = 0.011; Table 1).
Table 1.
Characteristics of Patients With Small Branches and Distal Aneurysms of the Posterior Circulation
| Fusiform/dissecting | Saccular | Total | ||
|---|---|---|---|---|
| (n = 13) | (n = 23) | P value | (n = 36) | |
| Age, y, median (IQR) | 58.0 (51.0–65.0) | 60.0 (55.0–64.5) | 0.448 | 60.0 (52.8–65.3) |
| Sex, n (%) | 0.096 | |||
| Female | 6 (46.2) | 17 (73.9) | 23 (63.9) | |
| Male | 7 (53.8) | 6 (26.1) | 13 (36.1) | |
| Baseline mRS, * n (%) | 0.945 | |||
| 0 | 9 (75.0) | 18 (78.3) | 27 (77.1) | |
| 1 | 3 (25.0) | 1 (4.3) | 4 (11.4) | |
| 2 | 0 (0) | 4 (17.4) | 4 (11.4) | |
| History of headache, n (%) | 3 (23.1) | 7 (30.4) | 0.716 | 10 (27.8) |
| Hyperlipidemia, n (%) | 3 (23.1) | 8 (34.8) | 0.708 | 11 (30.6) |
| Smoking, n (%) | 2 (15.4) | 11 (47.8) | 0.075 | 13 (36.1) |
| History of stroke or TIA, n (%) | 0 (0) | 6 (26.1) | 0.068 | 6 (16.7) |
| Ruptured aneurysm, n (%) | 8 (61.5) | 4 (17.4) | 0.011 † | 12 (33.3) |
| Baseline Hunt and Hess scale, ‡ n (%) | 0.006 † | |||
| 0 | 5 (45.5) | 19 (90.5) | 24 (75.0) | |
| 1 | 0 (0) | 1 (4.8) | 1 (3.1) | |
| 2 | 3 (27.3) | 1 (4.8) | 4 (12.5) | |
| 3 | 2 (18.2) | 0 (0) | 2 (6.3) | |
| 4 | 1 (9.1) | 0 (0) | 1 (3.1) | |
| Previous treatment, n (%) | 2 (15.4) | 7 (30.4) | 0.438 | 9 (25.0) |
| Endovascular | 2 (100) | 7 (100) | 9 (100) | |
| Aneurysm location, n (%) | ||||
| Anterior inferior cerebellar artery | 0 (0) | 4 (17.4) | 0.058 | 4 (11.1) |
| Posterior inferior cerebellar artery | 9 (69.2) | 12 (52.2) | 21 (58.3) | |
| Posterior cerebral artery P2 | 3 (23.1) | 2 (8.7) | 5 (13.9) | |
| Posterior cerebral artery P3 | 1 (7.7) | 0 (0) | 1 (2.8) | |
| Superior cerebellar artery | 0 (0) | 5 (21.7) | 5 (13.9) | |
| Position, § n (%) | >0.999 | |||
| Bifurcation | 0 (0) | 1 (4.8) | 1 (3.0) | |
| Sidewall | 12 (100) | 20 (95.2) | 32 (97.0) | |
| Aneurysm measurements, mm, median (IQR) | ||||
| Size * | 5.0 (3.6–11.0) | 4.5 (3.0–6.1) | 0.147 | 4.8 (3.2–6.9) |
| Dome height || | 4.5 (3.3–9.7) | 3.9 (2.7–5.2) | 0.165 | 4.0 (2.9–6.0) |
| Dome width | 4.3 (2.8–6.0) | 3.8 (2.6–4.7) | 0.542 | 3.9 (2.6–5.6) |
| Vessel measurements, mm, median (IQR) | ||||
| Maximum proximal diameter || | 1.9 (1.7–2.6) | 3.0 (2.6–3.5) | 0.027 † | 2.8 (2.0–3.5) |
| Maximum distal diameter || | 1.8 (1.6–2.5) | 2.7 (2.5–3.2) | 0.056 | 2.5 (1.8–3.1) |
| Vessel branch arising from dome, n (%) | 1 (7.7) | 6 (26.1) | 0.180 | 7 (19.4) |
| Preprocedure antiplatelet regimen (start time ≥ 7 d), n (%) | 0.168 | |||
| Aspirin | 0 (0) | 1 (4.3) | 1 (2.8) | |
| Aspirin and clopidogrel | 6 (46.2) | 16 (69.6) | 22 (61.1) | |
| Aspirin and ticagrelor | 3 (23.1) | 5 (21.7) | 8 (22.2) | |
| Ticagrelor | 1 (7.7) | 0 (0) | 1 (2.8) | |
| No | 3 (23.1) | 1 (4.3) | 4 (11.1) | |
IQR indicates interquartile range; mRS, modified Rankin Scale; and TIA, transient ischemic stroke.
Categorical variables were compared using the χ2 test or the Fisher exact test, as appropriate. Continuous variables were compared using the Mann–Whitney U test. Ordinal variables including baseline mRS and Hunt and Hess scale were compared using mixed‐effects ordinal logistic regression.
indicates significant difference (P < 0.05).
Missing data for:
= 1;
= 4;
= 3;
= 2.
Treatment and Outcomes
Most of the aneurysms were successfully treated with a single flow diverter (29/36, 80.6%; Table 2) using femoral access (29/36, 80.6%). There were 54.3% (19/35) of the aneurysms that were treated with a direct FD implantation in the small parent vessel as compared with 45.7% (16/35) that had indirect implantation in the vertebral artery. Adjunctive coiling and balloon‐assisted angioplasty were performed in 1 (2.8%) and 5 (13.9%) patients, respectively. The majority of patients had modified Rankin Scale score 0 to 2 status at last follow‐up (29/32, 90.6%). Complete occlusion was achieved in 78.1% (25/32; Figure ) for the entire cohort at a median follow‐up of 14.1 months (IQR, 10.1–49.1 months). There were higher rates of complete occlusion using the Raymond–Roy occlusion scale in fusiform/dissecting aneurysms as compared with saccular aneurysms, although this difference was not statistically significant (91.7% versus 70.0%; P = 0.151). Digital subtraction angiography was performed in 18 patients. Complete occlusion (class D) on the O'Kelly Marotta scale was observed in 16 (88.9%) of them, and there was no significant difference between the 2 groups (P>0.999). There was no difference in Raymond–Roy complete occlusion rates between aneurysms that were treated with a direct FD implantation in the parent vessel as compared with those that had indirect implantation in the vertebral artery after adjusting for morphology (87.5% versus 66.7%; P = 0.523). Major stroke (ischemic/hemorrhagic) was observed in 2 cases (5.6%) who had saccular aneurysms. One patient presented a month after the procedure with clinical presentation and imaging evidence of new ischemic strokes in the parent vessel of the treated aneurysm. The other patient had a hemorrhagic stroke in the parent vessel of the treated aneurysm during hospitalization. Comparison in outcomes between patients with ruptured and unruptured aneurysms are shown in Table S2. Two patients had a deep hematoma at the puncture site that improved in a few hours. In‐stent (<50%) stenosis was observed in 4 (11.1%) cases. A patient had a subocclusive thrombus at the level of the aneurysm neck following FD deployment, which was successfully managed with Integrilin and angioplasty and was asymptomatic. Only 1 (2.8%) case using the PED Shield had fishmouthing that required angioplasty, and for that a second device was deployed. Retreatment was required for 4 aneurysms (11.4%), 3 with additional FD deployment and 1 with surgical clipping. There was no significant increase in rates of major stroke (0% versus 8.7%; P = 0.525), or retreatment rates (7.7% versus 13.6%; P>0.999) between fusiform/dissecting and saccular aneurysms.
Table 2.
Treatment and Outcomes of Patients With Small Branches and Distal Aneurysms of the Posterior Circulation
| Fusiform/dissecting | Saccular | Total | ||
|---|---|---|---|---|
| (n = 13) | (n = 23) | P value | (n = 36) | |
| Access site, n (%) | >0.999 | |||
| Femoral | 11 (84.6) | 18 (78.3) | 29 (80.6) | |
| Radial | 2 (15.4) | 5 (21.7) | 7 (19.4) | |
| Total number of flow diverters implanted, n (%) | 0.225 | |||
| 1 | 9 (69.2) | 20 (87.0) | 29 (80.6) | |
| >1 | 4 (30.8) | 3 (13.0) | 7 (19.4) | |
| Adjunctive coiling, n (%) | 0 (0) | 1 (4.3) | >0.999 | 1 (2.8) |
| Balloon‐assisted angioplasty, n (%) | 1 (7.7) | 4 (17.4) | 0.634 | 5 (13.9) |
| Postprocedure antiplatelet regimen, n (%) | >0.999 | |||
| Aspirin and clopidogrel | 9 (69.2) | 15 (65.2) | 24 (66.7) | |
| Aspirin and ticagrelor | 4 (30.8) | 8 (34.8) | 12 (33.3) | |
| Immediate RRO scale, * n (%) | 0.518 | |||
| 1 | 1 (8.3) | 1 (4.3) | 2 (5.7%) | |
| 2 | 0 (0) | 3 (13.0) | 3 (8.6%) | |
| 3 | 11 (91.7) | 19 (82.6) | 30 (85.7%) | |
| Time from procedure to final follow‐up, mo, median (IQR) † | 14.1 (5.1–49.1) | 12.9 (10.8–45.5) | 0.543 | 14.0 (9.3–48.6) |
| Final follow up RRO scale, ‡ n (%) | 0.162 | |||
| 1 | 11 (91.7) | 14 (70.0) | 25 (78.1) | |
| 2 | 1 (8.3) | 2 (10.0) | 3 (9.4) | |
| 3 | 0 (0) | 4 (20.0) | 4 (12.5) | |
| RRO complete occlusion, ‡ n (%) | 11 (91.7) | 14 (70.0) | 0.151 | 25 (78.1) |
| Major stroke (ischemic/hemorrhagic), n (%) | 0 (0) | 2 (8.7) | 0.525 | 2 (5.6) |
| Last follow‐up mRS, ‡ n (%) | 0.389 | |||
| 0 | 8 (66.7) | 15 (75.0) | 23 (71.9) | |
| 1 | 1 (8.3) | 3 (15.0) | 4 (12.5) | |
| 2 | 0 (0) | 2 (10.0) | 2 (6.3) | |
| 3 | 2 (16.7) | 0 (0) | 2 (6.3) | |
| 6 | 1 (8.3) | 0 (0) | 1 (3.1) | |
| Retreatment, * n (%) | 1 (7.7) | 3 (13.6) | >0.999 | 4 (11.4) |
| Clipping | 0 (0) | 1 (33.3) | 1 (25.0) | |
| Endovascular | 1 (100) | 2 (66.7) | 3 (75.0) | |
| Access site complications, n (%) | 1 (7.7) | 1 (4.3) | >0.999 | 2 (5.6) |
| Fishmouthing, n (%) | 0 (0) | 1 (4.3) | >0.999 | 1 (2.8) |
| Subocclusive thrombus, n (%) | 0 (0) | 1 (4.3) | >0.999 | 1 (2.8) |
| In‐stent stenosis, n (%) | 1 (7.7) | 3 (13.0) | >0.999 | 4 (11.1) |
IQR indicates interquartile range; mRS, modified Rankin Scale; and RRO, Raymond–Roy occlusion.
Categorical variables were compared using the χ2 test or the Fisher exact test, as appropriate. Continuous variables were compared using the Mann–Whitney U test. Ordinal variables including final follow up RRO scale and last follow‐up mRS were compared using mixed‐effects ordinal logistic regression. Missing data for:
= 1;
= 5;
= 4.
Figure .
Final follow‐up Raymond–Roy Occlusion scale rates in this study.
Discussion
The availability of data concerning the feasibility and safety of FD for distal aneurysms of the posterior circulation is limited. This study found that FD treatment for these patients exhibited high rates of complete occlusion for fusiform/dissecting aneurysms and acceptable rates for saccular aneurysms. Additionally, there were low rates of major stroke, retreatment or in‐stent stenosis, highlighting the safety profile of FD for distally located posterior circulation aneurysms. Our findings support the viability of FD use for these aneurysms, particularly those of fusiform/dissecting morphology.
FD for Distal Small Branches
The overall 78.1% complete occlusion rate at follow‐up is higher than the previously reported literature on FD in the posterior circulation (65%) and within the range observed in the literature on the anterior circulation (75%–91%). 11 , 12 However, the literature evaluating the rates of complete occlusion after FD for aneurysms in distal small branches of the posterior circulation is limited to smaller‐sized case series with complete occlusion rates that range widely between 41.7% and 100%. 13 , 14 , 15 Regarding clinical complications, the 5.6% overall rate of complications reported in this series is lower than the 22% pooled rate in a systematic review that evaluated the safety and efficacy of FD in posterior circulation aneurysms. 12 Furthermore, the use of FD in PICA aneurysms was associated with an overall complications rate of 7%. 15 Importantly, the anatomic complexity and configuration of the vessels and aneurysms of these distal branches can potentially influence the technical success, safety, and efficacy of FD.
Comparison With Other Endovascular and Open Surgical Techniques
Each endovascular approach to treating posterior circulation aneuryms presents distinct advantages and potential risks for complications. Table 3 summarizes our findings and compares them with previously published studies in which other techniques for the treatment of distal aneurysms of the posterior circulation were employed. Among the different modalities, the use of open surgical treatment for saccular distal aneurysms was shown to have the highest rates of complete occlusion (going up to as high as 94.8%) compared with the 70% we found in our saccular aneurysms treated by FD. 16 However, despite the higher occlusion rate, open surgical approaches carry an increased risk of postoperative complications such as lower cranial nerve palsies and hydrocephalus when compared with other endovascular treatment modalities. 16 , 17 , 18 Several studies have suggested that a new neurologic deficit after surgery occurs with an incidence ranging from 20% to 60%. 19 , 20 , 21 , 22 Moreover, the intricate relationship between these distal vessels, the brain stem, the cranial nerves, and important perforating branches makes the surgical approach challenging during the acute phase. As a result, endovascular techniques have become the primary treatment modality, especially in the acute phase. Notably, coil embolization of distal aneurysms of the posterior circulation has demonstrated good clinical results with relatively high angiographic occlusion rates and a safe profile in saccular aneurysms. 17 , 23 , 24 Consistent with previous literature, 15 , 25 our findings suggest that the use of FD for the treatment of saccular aneurysms was associated with acceptable rates of complete occlusion and low rates of complications, taking into account that FD may take longer to achieve complete occlusion 26 and might yield lower occlusion rates as compared with open surgical treatments and coiling. Unlike saccular aneurysms, the absence of a true neck in fusiform/dissecting aneurysms renders the management of these aneurysms by clipping and coiling technically difficult and makes aneurysm trapping, bypass, and, more recently, FD possible ways to manage these aneurysms. 27 , 28 This study found that the use of FD for fusiform/dissecting distal aneurysms of the posterior circulation was associated with high rates of complete occlusion (91.7%) without causing major strokes, supporting the use of FD for the treatment of distal aneurysms of the posterior circulation that are fusiform/dissecting. The particularly high rate of complete occlusion for dissecting aneurysms in comparison with saccular aneurysms is well documented in the literature. 29 It is assumed that FD may be advantageous for dissecting aneurysms, as it preserves the dissection flap against the vessel wall, thereby impeding the continued progression of the dissecting aneurysm. Also, it is important to mention that self‐occlusion of these aneurysms is reported in several case reports and can be attributed to several factors and mechanisms, including but not limited to the formation of thrombus in the dissecting aneurysm as well as self‐repair of the affected vessel wall. 30 , 31 , 32 , 33
Table 3.
Review of Literature to Compare Between Our Results and Other Modalities for the Treatment of These Aneurysms
| Posterior inferior cerebellar artery | Anterior inferior cerebellar artery | Superior cerebellar artery | Flow diversion (overall) (n=36) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| PED (n=14) | Coiling (n=23) | Open surgical (n=155) | Endovascular (n=300) | Coiling (n=7) | Open surgical (n=62) | Open surgical (n=12) | Endovascular (n=21) | ||
| Primary author | Wallace 15 | Mukonoweshuro 35 | Ali 16 | Ali 16 | Suh 24 | Rodríguez‐Hernández 18 | Jin 17 | Jin 17 | Our series |
| Fusiform/dissecting, % * | 21.4 | 0 | 0 | 0 | 0 | 4.8 | 0 | 4.8 | 36.1 |
| Complete occlusion, % | 41.7 | 82.4 | 94.8 | 69.1 | 71.4 | 91.7 | 75 | 57.1 | 78.1 |
| mRS score 0–2 at last follow‐up, % | ‐ | ‐ | 78.1 | 77.6 | 100 | ‐ | ‐ | ‐ | 90.6 |
| Neurological complications, % | 7.1 † | 17.4 ‡ | 22.7 § | 2.4 § | 0 | 21.0 || | 58.3 ¶ | 4.8 | 5.6 |
| Procedure related death, % | 0 | 0 | ‐ | ‐ | 0 | 0 | 0 | 0 | 0 |
| Mean/median imaging time † | 15 | 11 | ‐ | ‐ | 24 | ‐ | 33.3 | 35.7 | 14 |
| Retreatment, % | 14 | 8.3 | 4.6 | 11.4 | 0 | ‐ | 0 | ‐ | 11.4 |
mRS indicates modified Rankin Scale.
The remaining are saccular aneurysms except in Rodríguez‐Hernández et al, which has 14.3% blister aneurysms;
Those complications were transient;
8.7% were permanent;
rate for cranial nerve palsies;
4.8% were permanent;
41.7% had a third nerve palsy with most recovering on follow up. One patient had artery of Huebner injury, and 1 patient had parent vessel compromise.
FD Technical Events
In addition, our results in this study support the technical feasibility of using FD for the treatment of distal aneurysms. While these aneurysms are located in smaller and more distal vessels, we still found lower rates of in‐stent stenosis in distal aneurysms that were treated in this study by FD as compared with the in‐stent stenosis rates of FD in the literature (11.1% versus 15.0%). 34 Similarly, we found similar to low rates of fishmouthing in this study as compared with the rates reported for intracranial aneurysms treated by a flow redirection endoluminal device (2.8% versus 3.8%).
Limitations
This study is limited by its retrospective nature, which results in incomplete data sets, selection bias, and unidentified confounders. Moreover, the inclusion of multiple centers might result in variability in patient management. A standardized data sheet was used to collect the data from all centers. Additionally, this study is limited by the small sample size, lack of a core laboratory to adjudicate radiological outcomes, and the absence of blinded observers for the assessment of the clinical outcomes. This could have overestimated the radiographic outcomes and underestimated the clinical outcomes. Moreover, digital subtraction angiography was used to assess the angiographic outcome in only 50% of the sample, while the angiographic outcome for the others were assessed by magnetic resonance angiography and computed tomography angiography. This prevents us from assessing the O'Kelly Marotta occlusion scale for the whole sample. The inclusion of different iterations and generations of FD might result in differences in FD. However, recent results from our group showed no difference in efficacy and safety between 4 commonly used FD devices in different locations. 8 More importantly, all the studied cases were performed using the 0.27 or 0.21 delivery systems that are available in the United States. The use of low profiles, including the 0.17 systems, for these smaller vessel diameters may further increase the safety profile of FD in the current study locations.
Conclusion
This study supports the safety and feasibility of FD for distal aneurysms of the posterior circulation. Particularly, fusiform aneurysms may have a higher rate of occlusion and low rates of stroke complications. Further larger‐scale studies are warranted to confirm these findings.
Sources of Funding
This research received no specific grant from any funding agency in the public, commercial, or not‐for‐profit sector.
Disclosures
Drs Dibas, Vivanco‐Suarez, Rodriguez‐Calienes, Cortez, Nishi, Patterson, Feigen, Essibayi, Galecio‐Castillo, Matsoukas, Hafeez, Kuhn, Wakhloo, Rabinovich, Sauvageau, Aghaebrahim, Costa, Monteith, Farooqui—none. Pereira – Consultant: Stryker, Medtronic, Penumbra, Neurovasc, and Balt. Toth – Consultant: Medtronic and Dynamed. Altschul – Consultant: Microvention, Stryker, and Von Vascular Inc. Fifi – Consultant: Penumbra, Stryker, Microvention, and Cerenovus. Grants: Viz. Investor/Stoker: Imperative care and Cerebrotech. Kan – Consultant: Stryker, Imperative Care, Cerenovus, and Microvention. Grants: NIH, Siemens, Joe Niekro, and Medtronic. Editorial board: Journal of NeuroInterventional Surgery. Dr Puri – Consultant: Medtronic, Stryker, Cerenovus, Microvention, Agile, Merit, Corindus, Q'apel, Arsenal, and Imperative Care. Grants: Medtronic, Stryker, and Cerenovus. Dr Khandelwal – Consultant: Stryker and Medtronic. Dr Hanel – Consultant: Medtronic, Stryker, Cerenovous, Microvention, Balt, Phenox, Rapid Medical, and Q'Apel. Advisory board: MiVI, eLum, Three Rivers Medical Inc., Shape Medical, and Corindus. Grants: from the National Institutes of Health, Interline Endowment, Microvention, Stryker, and CNX. Investor/Stoker: InNeuroCo, Cerebrotech, eLum, Endostream, Three Rivers Medical Inc., Scientia, RisT, BlinkTBI, and Corindus. Dr Ortega‐Gutierrez – Grants: NIH‐NINDS (R01NS127114‐01, RO3NS126804‐01), Stryker, Medtronic, Microvention, Methinks, Viz.ai. Consulting fees: Medtronic, Stryker Neurovascular. Santiago Ortega‐Gutierrez and Ricardo A Hanel serves on the Editorial Board of S:VIN. Editorial Board Members are not involved in the handling or final disposition of submissions. Johanna Fifi is an Associate Editor for S:VIN and was not involved in the handling or final disposition of this article. Disclosures provided by Johanna Fifi in compliance with American Heart Association's annual Journal Editor Disclosure Questionnaire are available at https://www.ahajournals.org/editor-coi-disclosure.
Supporting information
Supplementary Text 1. Description of the types and characteristics of flow diverters in this study.
Supplementary Tables 1. Flow diverter devices, diameter and length used in this study.
Supplementary Tables 2. Comparison in outcomes between unruptured and ruptured distal aneurysms.
Acknowledgments
None.
This manuscript was sent to Dr. Andrei V. Alexandrov, Guest Editor, for review by expert referees, editorial decision, and final disposition.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Supplementary Text 1. Description of the types and characteristics of flow diverters in this study.
Supplementary Tables 1. Flow diverter devices, diameter and length used in this study.
Supplementary Tables 2. Comparison in outcomes between unruptured and ruptured distal aneurysms.