Background and Purpose: Endovascular coiling is widely used for treatment of both ruptured and unruptured aneurysms. Intracranial bifurcation aneurysms were classically considered unsuitable for endovascular treatment because of the risk of coil protrusion into the parent vessel. The introduction stent assisted coiling has allowed the bifurcation aneurysms to be endovascularly treated. The present study aims to evaluate the efficacy of the endovascular treatment of the intracranial bifurcation aneurysms. Methods: This study was conducted on 76 patients with radiologically documented intracranial aneurysms at bifurcation sites either ruptured (12 aneurysms) or unruptured (64 aneurysms). Endovascular coiling of intracranial aneurysms was done for all patients in our study aided in some with single or Y-configuration stenting. The radiological outcome was assessed immediately postoperative, and at follow-up at 6 and 12 month with grading of the angiograms on the basis of modified 3-point Raymond scale. Results: In terms of the Raymond grading (RG), the initial angiographic outcome was complete occlusion (RG1) in 45 aneurysms (59.2%), neck remnant (RG2) in 20 aneurysms (26.3%), and body filling (RG3) in 11 aneurysms (14.5%), while the final angiographic outcome at 1 year was RG1 in 55 aneurysms (72.4%), RG2 in 13 aneurysms (17.1%), and RG3 in 8 aneurysms (10.5%). Eleven aneurysms (14.5%) showed recanalization. The aneurysm size and the neck width were the statistically significant factors affecting the initial RG (P = 0.0005, 0.001 respectively), final RG (P = 0.015, 0.012 respectively), and the recanalization rate (P = 0.012, 0.01 respectively). Conclusions: Endovascular treatment of intracranial aneurysms at bifurcation sites is safe and effective. Stent assisted coiling (SAC) has enabled us to offer a safe and effective endovascular treatment for bifurcation aneurysms by preventing coils herniation. Smaller aneurysm size and neck size are indicators of complete occlusion and lower recanalization rate.
Intracranial aneurysm tends to occur at regions of sharp vessel curvature, and bifurcations such as the basilar bifurcation, the internal carotid artery (ICA) bifurcation, the middle cerebral artery (MCA) bifurcation, and the anterior communicating artery. The reason for this is unknown, but the heterogeneous distribution suggests the presence of local contributing factors such as high wall shear stress, turbulence, and other hemodynamic forces implicated in its pathogenesis [
Most intracranial aneurysms are clinically silent until rupture, which is unpredictable and sometimes associated with subarachnoid hemorrhage, intraparenchymal hemorrhage, and an intraventricular hemorrhage [
Decision for treatment of intracranial aneurysm is based on clinical and anatomic factors such as the patient’s age, family history of intracranial aneurysm, symptomatic aneurysms, aneurysm size, aneurysm location, and associated conditions like autosomal dominant polycystic kidney disease (ADPKD) [
Intracranial bifurcation aneurysms were previously considered unsuitable for endovascular treatment because of the risk of coil protrusion into the parent vessel and were typically managed by surgical clipping. Recent advancements in endovascular devices and techniques have placed such aneurysms within the range of endovascular therapy. The introduction of stent assisted coiling has allowed the bifurcation aneurysms to be endovascularly treated [
Follow-up imaging after endovascular management of intracranial aneurysm by digital subtraction angiography (DSA) or magnetic resonance angiography (MRA) is crucial. The most important reason for this follow-up is the fact that recanalization after coiling has a high frequency; the issue that exposes the patient to the risk of recurrent subarachnoid hemorrhage (SAH) [
Aim of the study: The aim of present study is to evaluate the efficacy of the endovascular treatment of the intracranial bifurcation aneurysms, and to analyze the factors that may affect the angiographic outcomes.
This study was conducted in the neurosurgery department at RUSH medical center, Chicago. IL, from December 2016 to May 2018. The inclusion criteria were:
1) Patients with radiologically documented ruptured or unruptured intracranial bifurcation aneurysms.
2) Patients physically fit for the endovascular treatment procedures.
It was conducted on76casesof bifurcation sites intracranial aneurysms either ruptured (12 aneurysms) or unruptured (64 aneurysms) after obtaining written informed consent from all patients. All patients are subjected to detailed history taking, physical examination, laboratory investigations. All the aneurysms were radiologically documented by conventional digital subtraction angiography (DSA).
Endovascular coiling of intracranial aneurysms was done for all patients in our study aided in some cases with single or Y-configuration stenting. Immediate postoperative angiographic runs were obtained in working projections to determine the angiographic end result. Patients were subjected to angiographic follow-up (DSA or MRA) at 6 and 12 month following the treatment. The degree of aneurysm occlusion was graded immediately after treatment and at follow up using modified Raymond grading, where grade 1, complete occlusion; grade 2, residual neck; and grade 3, aneurysm body filling [
Certain factors were analyzed in relation to angiographic outcomes like the pretreatment angiographic data and the treatment related factors. Pretreatment geometric data included aneurysm site, aneurysm size, neck width, dome-neck ratio, and aspect ratio. Treatment related factors included treatment modality, stent type, initial RG, and the packing density (≤24% or >24%). Packing density was available for only 51 aneurysms using AngioSuite software system (Cascade Medical, Knoxville, TN, USA).
Sample size was calculated. Data were statistically analyzed using SPSS 21 (IBM Corp. Armonk, New York). Statistical analysis was done for comparing variables between the groups using Mann-Whitney nonparametric test for numerical variables and Fisher’s exact test for categorical variables. P value ≤ 0.05 was considered to be statistically significant. Multivariable logistic regression was performed on candidate predictor variables to identify variables independently associated with occlusion after adjustment for potential confounders.
The current study was conducted on 76 radiologically documented aneurysms both ruptured and unruptured at different bifurcation sites.
1) Demographic data:
In the current study, 29 patients were males (38.2%) and 47 were females (61.8%) with male-to-female ratio of 1:1.6. The patients’ age ranged from 31 to 88 years, with a mean of 61 years (±12.4). Regarding male patients the mean age was 58.4 years (±11.8), whereas the mean age of the female patients was 62.7 years (±12.3). Out of the 76 patients included in the study 34 patients (44.7%) have no special habits, 30 patients (39.5%) were both cigarette smokers and alcoholics, 12patients (15.8%) were cigarette smokers only. The frequency of risk factors among the studied groups showed that hypertension was the commonest risk factor. Fifty four patients (71.1%) were hypertensive, 26 patients (34.2%) had dyslipidemia, and 5 (7.4%) patients had family history of aneurysms.
2) Clinical data:
Out of our study group, only 12 patients (16%) presented with SAH due to aneurysmal rupture. Most of the patients (31 patients, about 41%) presented by headache, only 4 patients (5%) presented by loss of consciousness, while the remaining (29 patients, about 38.2%) were incidentally discovered.
3) Pretreatment anatomical and geometric data:
The bifurcation aneurysm sites were distributed as follows: 30 (39.5%) in the basilar tip, 20 (26.33%) in the ICA terminus, 15 (19.7%) in the AcomA, and 11 (14.5%) in the MCA bifurcation. The median aneurysm size was 5 mm (range 1.4 - 17.4 mm), the mean neck width was 4.13 ± 1.64 (range 1.5 - 9 mm), dome neck ratio was 1.4 ± 0.6 (range 0 - 4), and aspect ratio was 1.45 ± 0.58 (range 0.5 - 3.7).
4) Treatment related factors:
Fifty three patients (69.7%) were treated by single SAC, 15 patients (19.7%) were treated by simple coiling, and 8 patients (10.5%) were treated by Y-stenting. Stents used were 39 Neuroform EZ (Stryker, Fremont, CA, USA), 9 Enterprise (Codman Neurovascular, Raynham, MA, USA), and 13 LVIS Jr. (Microvention, Tustin, CA, USA).
5) Treatment outcomes:
In terms of the RG, the initial angiographic outcome was complete occlusion (RG1) in 45 aneurysms (59.2%), neck remnant (RG2) in 20 aneurysms (26.3%), and body filling (RG3) in 11 aneurysms (14.5%). The 6 months’ angiographic outcome was RG1 in 58 aneurysms (76.3%), RG2 in 13 aneurysms (17.1), and RG3 in 5 aneurysms (6.6), while the final angiographic outcome at 12 months’ follow-up was RG1 in 55 aneurysms (72.4%), RG2 in 13 aneurysms (17.1%), and RG3 in 8 aneurysms (10.5%) (
Analysis of the factors affecting the angiographic outcome showed that the aneurysm size and the neck width were the statistically significant factors affecting
Demographic and clinical data | ||||
---|---|---|---|---|
Initial RG | ||||
1 N% | 2 N% | 3 N% | ||
45 (59.2) | 20 (26.3) | 11 (14.5) | 76 (100) | |
Age (years) Mean ± SD | 61.8 ± 11.6 | 61.5 ± 13.7 | 57.4 ± 12.1 | P = 0.56 |
Gender Male Female | 18 (62.1) 27 (57.4) | 8 (27.6) 12 (25.5) | 3 (10.3) 8 (17.0) | P = 0.72 |
Hypertension | 33 (61.1 | 13 (24.1) | 8 (14.8) | P = 0.78 |
Dyslipidemia | 16 (61.5) | 7 (26.9) | 3 (11.5) | P = 0.85 |
Smoking | 25 (59.5) | 10 (23.8) | 7 (16.7) | P = 0.81 |
Alcohol drinking | 15 (50.0) | 9 (30.0) | 6 (20.0) | P = 0.37 |
Clinical presentation ・ Unruptured ・ Ruptured | 38 (59.5) 7 (58.3) | 17 (26.5) 3 (25.0) | 9 (14.0) 2 (16.7) | P = 0.62 |
Pretreatment geometric data | ||||
Site ・ Basilar ・ Carotid ・ ACOM ・ MCA | 19 (63.3) 11 (55.0) 10 (66.7) 5 (45.5) | 8 (26.7) 7 (35.0) 2 (13.3) 3 (27.3) | 3 (10.0) 2 (10.0) 3 (20.0) 3 (27.3) | P = 0.64 |
Aneurysm size Mean ± SD | 4.5 ± 2.66 | 9.6 ± 3.76 | 5.61 ± 3.36 | F = 8.55 P = 0.0005* |
Neck width Mean ± SD | 3.13 ± 0.88 | 5.22 ± 1.9 | 3.90 ± 1.4 | F = 8.13 P = 0.001* |
Aspect ratio Mean ± SD | 1.47 ± 0.54 | 1.35 ± 0.49 | 1.56 ± 0.88 | F = 0.55 P = 0.58 |
Dome neck ratio Mean ± SD | 1.34 ± 0.51 | 1.4 ± 0.62 | 1.75 ± 0.89 | F = 2.05 P = 0.14 |
Treatment related factors | ||||
Treatment modality ・ Simple coiling ・ Single SAC ・ Y-stenting | 10 (66.7) 32 (60.4) 3 (37.5) | 3 (20.0) 13 (24.5) 4 (50.0) | 2 (13.3) 8 (15.1) 1 (12.5) | MC P = 0.61 |
Stent used ・ Neuroform ・ Enterprise ・ Elvis | 22 (61.3) 6 (66.7) 7 (53.8) | 12 (29) 1 (11.1) 3 (23.1) | 5 (9.7) 2 (22.2) 3 (23.1) | MC P = 0.67 |
Demographic and clinical data | ||||
---|---|---|---|---|
Final RG | ||||
1 N (%) | 2 N (%) | 3 N (%) | ||
55 (72.4) | 13 (17.1) | 8 (10.5) | 76 (100) | |
---|---|---|---|---|
Age (years) Mean ± SD | 62 ± 11.9 | 54.7 ± 13.4 | 64.7 ± 9 | P = 0.09 |
Gender ・ Male ・ Female | 21 (72.4) 34 (72.3) | 1 (24.1) 6 (12.8) | 1 (3.4) 7 (14.9) | P = 0.16 |
Hypertension | 38 (70.4) | 10 (18.5) | 6 (11.1) | P = 0.85 |
Dyslipidemia | 18 (69.2) | 5 (19.2) | 3 (11.5) | P = 0.93 |
Smoking | 31 (73.8) | 9 (21.4) | 2 (4.8) | P = 0.13 |
Alcohol drinking | 18 (60.0) | 8 (26.7) | 4 (13.3) | P = 0.13 |
Clinical presentation ・ Unruptured ・ Ruptured | 45 (70.4) 10 (83.3) | 11 (17.1) 2 (16.7) | 8 (12.5) 0 (0.0) | P = 0.65 |
Pretreatment geometric data | ||||
Site ・ Basilar ・ Carotid ・ ACOM ・ MCA | 19 (63.3) 15 (75.0) 12 (80.0) 9 (81.8) | 6 (20.0) 3 (15.0) 2 (13.3) 2 (18.2) | 5 (16.7) 2 (10.0) 1 (6.7) 0 (0.0) | P = 0.78 |
Aneurysm size Mean ± SD | 5.6 ± 3.1 | 7.5 ± 4.1 | 9.5 ± 5.2 | F = 4.45 P = 0.015* |
Neck width Mean ± SD | 3.81 ± 1.4 | 4.75 ± 2.1 | 5.39 ± 1.99 | F = 4.73 P = 0.012* |
Aspect ratio Mean ± SD | 1.45 ± 0.55 | 1.34 ± 0.75 | 1.65 ± 0.52 | F = 0.69 P = 0.50 |
Dome neck ratio Mean ± SD | 1.38 ± 0.59 | 1.3 ± 0.60 | 1.81 ± 0.62 | F = 2.02 P = 0.14 |
Treatment related factors | ||||
Treatment modality ・ Simple coiling ・ Single SAC ・ Y-stenting | 12 (80.0) 40 (75.5) 3 (37.5) | 3 (20.0) 8 (15.1) 2 (25.0) | 0 (0.0) 5 (9.4) 3 (37.5) | P = 0.53 |
Stent used ・ Neuroform ・ Enterprise ・ Elvis | 29 (83.9) 6 (66.7) 8 (61.5) | 6 (9.7) 3 (33.3) 2 (15.4) | 4 (6.5) 0 (0.0) 3 (23.1) | P = 0.13 |
the initial RG (P = 0.0005, 0.001 respectively), final RG (P = 0.015, 0.012 respectively), and the recanalization rate (P = 0.012, 0.01 respectively) (Tables 1-3).
The present study consisted of series of 76 aneurysms at 4 different bifurcation sites (basilar tip, ICA terminus, MCA bifurcation, and AcomA) treated by different endovascular modalities. Clinical and angiographic data were collected. Aneurysm occlusion after treatment was categorized according to modified Raymond classification. At follow-up, an aneurysm was considered recanalized
Demographic and clinical data | |||
---|---|---|---|
Recanalization | |||
No | Yes | ||
65 (85.5) | 11 (14.5) | 76 (100) | |
Age (years) Mean ± SD | 60.9 ± 12.8 | 62.1 ± 7.9 | P = 0.77 |
Gender ・ Male ・ Female | 26 (89.7) 39 (83.0) | 3 (10.3) 8 (17.0) | P = 0.72 |
Hypertension | 45 (83.3) | 9 (16.7) | P = 0.39 |
Dyslipidemia | 22 (84.6) | 4 (15.4) | P = 0.89 |
Smoking | 37 (88.1) | 5 (11.9) | P = 0.48 |
Alcohol drinking | 24 (80.0) | 6 (20.0) | P = 0.27 |
Clinical presentation ・ Unruptured ・ Ruptured | 54 (84.4) 11 (91.7) | 10 (15.6) 1 (8.3) | P = 0.73 |
Pretreatment geometric data | |||
Site ・ Basilar ・ Carotid ・ ACOM ・ MCA | 23 (76.7) 17 (85.0) 14 (93.3) 11 (100) | 7 (233) 3 (15.0) 1 (6.7) 0 (0.0) | P = 0.22 |
Aneurysm size Mean ± SD | 5.9 ± 3.4 | 8.8 ± 4.9 | t = −2.31 P = 0.012* |
Neck width Mean ± SD | 3.9 ± 1.54 | 5.30 ± 1.81 | t = −0.29 P = 0.01* |
Aspect ratio Mean ± SD | 1.40 ± 0.54 | 1.74 ± 0.78 | t = −1.83 P = 0.07 |
Dome neck ratio Mean ± SD | 1.36 ± 0.60 | 1.71 ± 0.58 | t = −1.82 P = 0.07 |
Treatment related factors | |||
Treatment modality ・ Simple coiling ・ Single SAC ・ Y-stenting | 14 (93.3) 46 (86.8) 5 (62.5) | 1 (6.7) 7 (13.2) 3 (37.5) | P = 0.11 |
Initial RG ・ Complete occlusion ・ Residual neck ・ Body filling | N (%) 39 (60.0) 16 (24.6) 10 (15.4) | N (%) 6 (54.6) 4 (36.4) 1 (9.0) | P = 0.57 |
Packing density ・ ≤24 ・ >24 | N = 42 26 (61.9) 16 (38.1) | N = 9 3 (33.3) 6 (66.7) | P = 0.39 |
Stent used ・ Neuroform ・ Enterprise ・ Elvis | 33 (90.3) 8 (88.9) 10 (76.9) | 6 (9.7) 1 (11.1) 3 (23.1) | P = 0.55 |
if any further filling of the aneurysm neck or sac was observed compared with the initial treatment findings [
About 70% of the patients were treated by single SAC, 19.7% were treated by simple coiling, and 10.5% were treated by Y-stenting. Stent-assisted coiling (SAC) of bifurcation aneurysms has expanded the spectrum of aneurysms amenable to endovascular therapy by providing neck coverage while preserving the involved vessels from coil prolapsed [
In terms of the percentage of complete occlusions, the initial and follow up angiographic results are in range to the majority of results from previously published endovascular series, where complete occlusion has been achieved initially in 26% - 76% of the treated aneurysms and in follow-up in 35% - 86% (
Study | Number of aneurysms | Initial | Follow up months | Follow-up | ||||
---|---|---|---|---|---|---|---|---|
RG1 % | RG2 % | RG3 % | RG1 % | RG2 % | RG3 % | |||
Brilstra et al. 1999 [ | 201 | 61 | 26 | 13 | NA | NA | NA | NA |
Raymond & Roy 1997 [ | 75 | 40 | 37 | 23 | 6 | 46 | 42 | 12 |
Kuether et al. 1998 [ | 74 | 40 | 52 | 8 | 26 | 41 | 46 | 13 |
Byrne et al. 1999 [ | 317 | NA | NA | NA | 22 | 64 | 34 | 2 |
Vanninen et al. 1999 [ | 52 | 50 | 35 | 15 | 3 | 67 | 28 | 5 |
Koivisto et al. 2000 [ | 52 | 50 | 35 | 15 | 12 | 77 | 19 | 4 |
Ng et al. 2002 [ | 136 | 46 | 16 | 38 | NA | NA | NA | NA |
Friedman et al. 2003 [ | 83 | 33 | 63 | 5 | 19 | 35 | 61 | 3 |
Murayama et al. 2003 [ | 818 | 55 | 35 | 10 | NA | NA | NA | NA |
Sluzewski et al. 2003 [ | 160 | 71 | 22 | 8 | 6 | 59 | 25 | 16 |
Henkes et al. 2004 [ | 1811 | 66 | 21 | 13 | NA | NA | NA | NA |
Cronqvist et al. 2005 [ | 46 | 37 | 50 | 13 | NA | NA | NA | NA |
Molyneux et al. 2005 [ | 881 | NA | NA | NA | NA | 66 | 26 | 8 |
Norbäck et al. 2005 [ | 239 | 53 | 21 | 26 | NA | NA | NA | NA |
Geyik et al. 2010 [ | 80 | 71 | 28 | 1 | 10.5 | 86 | 8 | 6 |
Maldonado et al. 2010 [ | 76 | 31 | 26 | 42 | 16.4 | 65 | 13 | 13 |
---|---|---|---|---|---|---|---|---|
Yue, 2011 [ | 80 | 76 | 10 | 14 | NA | NA | NA | NA |
Nanda et al. 2013 [ | 66 | 72 | NA | NA | NA | NA | NA | NA |
Liu et al. 2017 [ | 113 | 26 | 61 | 13 | NA | NA | NA | NA |
Adeeb et al. 2017 [ | 74 | 53 | 23 | 24 | 15 | 70 | 20 | 9 |
Our study | 76 | 59.2 | 26.3 | 14.5 | 14 | 72.4 | 17.1 | 10.5 |
These results obtained (complete occlusion initially in 59.2% of the aneurysms) are comparable to the range of the published series [
In the present study, recanalization was present in only 14.5% of the aneurysms at the latest follow up which is less than most of the literature reports. The reported rates of aneurysm recanalization vary over a wide range from 17% to 90% [
Variety of factors influence the rate of occlusion and recanalization including aneurysm-specific factors such as size, neck width, dome-to-neck ratio, location and whether the aneurysm is ruptured or unruptured, and treatment-related factors such as the treatment modality, packing density, and the initial RG [
The major limitation of our study was the follow up interval. Our follow up interval was 12 months; longer intervals may be more conclusive.
Endovascular treatment of intracranial aneurysms at bifurcation sites is safe and effective. Stent assisted coiling (SAC) has enabled us to offer a safe and effective endovascular treatment for bifurcation aneurysms by preventing coils herniation. Smaller aneurysm size and neck size are indicators of complete occlusion and lower recanalization rate.
The authors declare no conflicts of interest regarding the publication of this paper.
Saied, A., Gomaa, M., Amer, T., Saad, M. and Lopes, D. (2018) Outcomes of Endovascular Treatment of Intracranial Aneurysms at Bifurcation Site. World Journal of Neuroscience, 8, 432-443. https://doi.org/10.4236/wjns.2018.84034