Abstract
Background
Endovascular coiling of small, intracranial aneurysms remains controversial and difficult, despite advances in technology.
Methods
We retrospectively reviewed data for 62 small aneurysms (<3.99 mm) in 59 patients. Occlusion rates, complications rates, and coil packing densities were compared between subgroups based upon coil type and rupture status.
Results
Ruptured aneurysms predominated (67.7%). Aneurysms measured 2.99 ± 0.63 mm by 2.51 ± 0.61 mm with an aspect ratio of 1.21 ± 0.34 mm. Brands included Optima (Balt) (29%), MicroVention Hydrogel (24.2%), and Penumbra SMART (19.4%) coil systems. Average packing density was 34.3 ± 13.5 mm3. Occlusion rate was 100% in unruptured aneurysms; 84% utilized adjuvant devices. For ruptured aneurysms, complete occlusion or stable neck remnant was achieved in 88.6% while recanalization occurred in 11.4%. No rebleeding occurred. Average packing density (p = 0.919) and coil type (p = 0.056) did not impact occlusion. Aspect ratio was smaller in aneurysms with technical complications (p = 0.281), and aneurysm volume was significantly smaller in those with coil protrusion (p = 0.018). Complication rates did not differ between ruptured and unruptured aneurysms (22.6 vs. 15.8%, p = 0.308) or coil types (p = 0.830).
Conclusion
Despite advances in embolization devices, coiling of small intracranial aneurysms is still scrutinized. High occlusion rates are achievable, especially in unruptured aneurysms, with coil type and packing density suggesting association with complete occlusion. Technical complications may be influenced by aneurysm geometry. Advances in endovascular technologies have revolutionized small aneurysm treatment, with this series demonstrating excellent aneurysm occlusion especially in unruptured aneurysms.
Keywords: Small, intracranial, aneurysm, endovascular, coil
Introduction
While endovascular coiling has been shown to result in better functional outcomes for ruptured intracranial aneurysms1,2 and equivalent outcomes for unruptured aneurysms, 3 the treatment of small intracranial aneurysms remains controversial. There is no standardized definition for “small” aneurysms: most studies classify aneurysms less than 3 mm4,5 or 4 mm 6 in diameter as small, although some use 5 mm 1 or even 7 mm. 7 Unruptured small aneurysms are thought to be more stable than large aneurysms, with multiple prospective series demonstrating a clear size association between aneurysm size and risk of rupture.5,7,8 Despite their association with a lower rupture risk, the vast majority of ruptured aneurysms seen in practice are small aneurysms.7,9 Therefore, optimizing treatment strategies for these lesions is paramount.
Endovascular treatment (via coiling) of small aneurysms is thought to be associated with significant treatment risk when compared to larger aneurysms or surgical clipping. 5 Small aneurysm volume can lead to an increased chance of coil herniation as well as aneurysm rupture with coil placement. However, underpacking aneurysms with fewer coils can lead to increased risk of recanalization with a potential for rebleeding or retreatment. Intraprocedural rupture has been seen in up to 7–8% of endovascularly coiled small aneurysms with thromboembolic complications in up to 4–5%.4,5 Recanalization rates can range from 4 to 15%.4,6,10,11 These considerations highlight the complexity of coil embolization of small aneurysms; therefore, surgical clipping is often still the mainstay of treatment of these lesions. 2
The use of smaller and softer coils has revolutionized the treatment of small aneurysms. 12 Recently, many companies have developed new, soft bare platinum coils designed for potential use even exceedingly small aneurysms.6,10,12 There have been previous studies demonstrating the efficacy of these new coil types in small aneurysms;6,10,12 however, only one study has compared more than two coil types 13 and none has done so for small aneurysms. In this study, we describe our experiences using coils designed for treating small aneurysms and the efficacy and outcomes we observed.
Methods
This study is an Institutional Review Board (IRB)-approved retrospective review of all patients treated for ruptured or unruptured intracranial aneurysms with endovascular coil embolization between 2017 and 2022. Patient consent was waived with institutional approval. An existing database of coil-treated patients from our institution was searched for all small aneurysms. Given the lack of a consistent definition of small aneurysm, we included all aneurysms with the largest diameter (height or width) ≤3.99 mm. Aneurysm treatment modality was based on discussion within an interdisciplinary neurointerventional and neurosurgical team.
Data collected included age at time of treatment, sex, medical history, smoking status, medication use, and prior aneurysm treatment or diagnosis. Presenting symptom and rupture status, with modified Fisher Scale and Hunt and Hess classification when applicable, were collected. Aneurysm dimensions, volume, and location were determined by catheter cerebral angiography. Endovascular treatment data collected included use of balloon, stent, or flow diverter assistance, number and brand of coils, and brand of microcatheter. Additionally, coil packing density was determined by autosegmented aneurysm volumes and AngioCalc software and was included in the analysis.
The primary outcome for this study was aneurysm occlusion on follow-up imaging. Both immediate postprocedure and follow-up angiographic findings were determined by Roy–Raymond occlusion classification (RROC). Secondary outcomes include intraprocedural technical and postprocedural clinical complications including rupture, coil protrusion, and thromboembolization causing ischemic stroke. All outcomes were controlled for coil types and rupture status. All follow-up data were collected from either digital subtraction angiography (DSA) or magnetic resonance angiography (MRA).
Statistical analysis
The primary endpoint, aneurysm occlusion rates, was analyzed with Kaplan–Meier estimates and calculated for the entire small aneurysm cohort as well as compared between subgroups of coil types and rupture statuses. Secondary endpoints were calculated using the appropriate statistical tests (chi-square analysis, independent t-test, and ANOVA). All statistical analyses are reported with ranges, 95% confidence intervals, or standard deviations when appropriate and considered statistically significant if p < 0.05. Statistical analysis was conducted with IBM SPSS Statistics (Version 29).
Results
Patient characteristics
Fifty-nine patients underwent endovascular treatment for 62 small aneurysms with coiling as the primary treatment modality. Average age was 56.3 (range: 20–93) and 42 (71.2%) were female (Table 1). Forty-two patients (71.2%) presented with subarachnoid hemorrhage (SAH). Further demographic information can be found in Table 1. Two (3.4%) patients were taking anticoagulants, 19 (32.2%) were taking aspirin, and 11 (18.6%) were taking clopidogrel. Multiple aneurysms were present in 22 (35.6%) patients. Indication for treatment of unruptured aneurysm included previous SAH (3), failure of previous treatment (4), previous or concurrent treatment of another aneurysm (7), multiple aneurysms (2), uncontrolled hypertension with symptoms (2), and active smoking (1).
Table 1.
Demographic information for 59 patients who underwent endovascular treatment for small, intracranial aneurysms.
| Age (average, range) | 56.3 | 20–93 |
| Sex (N, %) | ||
| Male | 17 | 28.8 |
| Female | 42 | 71.2 |
| Presenting symptom (N, %) | ||
| Headache | 34 | 54.8 |
| Seizure | 3 | 4.8 |
| Fall | 2 | 3.2 |
| Syncope | 4 | 6.5 |
| Asymptomatic | 15 | 24.2 |
| Cardiac arrest | 1 | 1.6 |
| AMS | 1 | 1.6 |
| Other | 2 | 3.2 |
| Modified Fisher Scale (N, %) | ||
| Grades 1 and 2 | 7 | 16.7 |
| Grades 3 and 4 | 35 | 83.3 |
| Hunt and Hess Scale (N, %) | ||
| Grades 1 and 2 | 24 | 57.1 |
| Grades 3–5 | 18 | 42.9 |
| Medical history (N, %) | ||
| HTN | 33 | 55.9 |
| HLD | 13 | 22.0 |
| CAD | 1 | 1.7 |
| DM | 3 | 5.1 |
| Previous SAH | 3 | 5.1 |
| CVA/TIA | 1 | 1.7 |
| Smoking (N, %) | ||
| Yes | 12 | 20.3 |
| Unknown | 1 | 1.7 |
| No | 49 | 83.1 |
| >1 aneurysm (N, %) | 22 | 37.3 |
| Previous treatment (N, %) | ||
| Same aneurysm | 7 | 11.9 |
| Other aneurysm | 10 | 16.9 |
| Medications (N, %) | ||
| Anticoagulation | 2 | 3.4 |
| Aspirin | 19 | 32.2 |
| Clopidogrel | 11 | 18.6 |
AMS, altered mental status; CAD, coronary artery disease; CVA, cerebrovascular accident; DM, diabetes mellitus; HLD, hyperlipidemia; HTN, hypertension; SAH, subarachnoid hemorrhage; TIA, transient ischemic attack.
Aneurysm characteristics and treatment
Of the 62 treated aneurysms, 43 (69.4%) were ruptured and 19 (30.6%) were unruptured (Table 2). Aneurysms were most commonly originating from the anterior communicating artery (ACOM) (17, 27.4%), middle cerebral artery (MCA) (12, 19.4%), and internal carotid artery (ICA) (8, 12.9%). Daughter sacs were found in nine (14.5%) aneurysms. Average aneurysm height was 2.99 mm (standard deviation [SD] 0.63 mm) with an average width of 2.51 mm (SD 0.61 mm) and an average neck of 2.32 mm (SD 0.72 mm). Average aneurysm volume was 14.7 mm3 (SD 8.28 mm3). Mean aspect ratio was 1.21 (SD 0.34) and mean dome-to-neck ratio was 1.13 (SD 0.22). The average neck surface area was 5.64 mm2 (SD 2.5 mm2). Unruptured aneurysms were significantly larger than ruptured aneurysms (18.8 vs. 13.2 mm3, p = 0.14).
Table 2.
Characteristics of the 62 small, intracranial aneurysms that were treated with endovascular coiling.
| Entire cohort (N = 62) | Ruptured (N = 43) | Unruptured (N = 19) | |
|---|---|---|---|
| Location (N, %) | |||
| ICA | 8 (12.9) | 2 (4.7) | 6 (31.6) |
| ACA | 6 (9.7) | 5 (11.6) | 1 (5.3) |
| ACOM | 17 (27.4) | 14 (32.6) | 3 (15.8) |
| MCA | 12 (19.4) | 9 (20.9) | 3 (15.8) |
| PCOM | 7 (11.3) | 5 (11.6) | 2 (10.5) |
| Basilar | 4 (6.5) | 2 (4.7) | 2 (10.5) |
| Other posterior circ. | 8 (12.9) | 6 (14.0) | 2 (10.5) |
| Aneurysm features (N, %) | |||
| Daughter sac | 9 (14.5) | 9 (14.5) | 0 (0) |
| Aneurysm dimensions (mean, SD) | |||
| Height | 2.99 (0.63) | 3.03 (0.66) | 2.94 (0.57) |
| Width | 2.51 (0.61) | 2.54 (0.63) | 2.43 (0.59) |
| Volume | 14.86 (8.28) | 13.22 (7.13)* | 18.8 (9.5)* |
| Neck | 2.32 (0.72) | 2.31 (0.75) | 2.34 (0.68) |
| Aspect ratio | 1.21 (0.34) | 1.17 (0.31) | 1.27 (0.39) |
| Dome:neck ratio | 1.13 (0.22) | 1.10 (0.20) | 1.17 (0.26) |
| Neck surface area | 5.64 (2.5) | 5.16 (2.14) | 6.50 (2.97) |
ACA, anterior cerebral artery; ACOM, anterior communicating artery; ICA, internal carotid artery; MCA, middle cerebral artery; PCOM, posterior communicating artery; SD, standard deviation.
*Independent t-test comparing these values resulted in p < 0.05.
As per our inclusion criteria, all aneurysms were treated with endovascular coiling (Table 3). Forty-nine aneurysms were treated with a single brand of coils and 13 (21%) received multiple coil types within the same aneurysm. Balt Optima/OptiMAX Supersoft Coil System was used in 18 (29%), MicroVention HyperSoft 3D and HyperSoft Helical Platinum coils in 2 (3.2%), MicroVention Hydroframe and Hydrosoft Hydrogel coils in 15 (24.2%), Penumbra SMART COIL Extra Soft System in 12 (19.4%), and Avenir Coil System (Wallaby Medical) in 2 (3.2%). On average, 2.90 coils were used for treatment, ranging from one to six coils. Average coil packing density achieved for the entire cohort was 34.3% (SD 13.5%).
Table 3.
Treatment specifics for the 62 small, intracranial aneurysms that were treated with endovascular coiling.
| Balloon use (N, %) | 52 | 83.9 |
| Balloon type (N, %) | ||
| Eclipse 2L | 31 | 50.0 |
| Scepter XC | 20 | 32.3 |
| Hyperform/Hyperglide | 1 | 1.6 |
| Unspecified | 3 | 4.8 |
| Stent use (N, %) | 8 | 12.9 |
| Flow diverter (N, %) | 12 | 19.4 |
| FRED | 4 | 6.5 |
| Pipeline | 7 | 11.3 |
| WEB | 1 | 1.6 |
| Microcatheter (N, %) | ||
| Echelon-10 | 17 | 27.4 |
| Echelon-14 | 35 | 56.5 |
| Excelsior SL-10 | 2 | 3.2 |
| Headway Duo | 8 | 12.9 |
| Coils used (N, %) | ||
| Balt Optima/OptiMAX Supersoft Coil System | 18 | 29.0 |
| MicroVention Hypersoft Platinum Coils | 2 | 3.2 |
| MicroVention Hydroframe and Hydrosoft Hydrogel Coils | 15 | 24.2 |
| Penumbra SMART COIL Extra Soft System | 12 | 19.4 |
| Avenir Coil System | 2 | 3.2 |
| Multiple | 13 | 21.0 |
| CPD (mean, SD) | 34.32 | 13.5 |
| No. of coils (mean, range) | 2.9 | 1–6 |
CPD, coil packing density; MV, MicroVention; No., number; SD, standard deviation; WEB, Woven EndoBridge device.
Balloon-assisted coiling was used in the treatment of 52 (83.9%) aneurysms. Balloons used included Eclipse 2L (31, 50%), Scepter XC (20, 32.3%), and Hyperform (1, 1.6%). Stent-assisted coiling was used in 8 (12.9%) aneurysms, and flow-diverter assistance was used in 12 aneurysms utilizing FRED (4, 6.5%) and Pipeline (7, 11.3%). Microcatheters used included Echelon-10 (17, 27.4%), Echelon-14 (35, 56.5%), Excelsior SL-10 (2, 3.2%), and Headway Duo (8, 12.9%).
Complications
Intraoperative rupture occurred in three patients (4.8%) (Table 4). Technical complications, using a broad definition, were seen in 14 cases and included coil protrusion (5, 8.1%), thrombus formation (6, 9.7%), and intraoperative rupture (3, 4.8%). Clinical complications included any infarction (5, 8.1%) and significant intraoperative rupture with no lasting deficit (1, 1.6%). Two of the ischemic complications were minor with resolution by discharge and three led to persistent neurological deficit. Therefore, the rate of major clinical complications was 4.8%. Average aspect ratio was smaller in aneurysms with technical complications (1.23 vs. 1.16, p = 0.281). Average aneurysm volume was significantly smaller in those complicated by coil protrusion (9.86 vs. 15.45 mm3, p = 0.018). There was no difference in technical complication rate when comparing ruptured and unruptured aneurysms (22.6 vs. 15.8%, p = 0.308) and between coil types (p = 0.83).
Table 4.
Outcomes and complication data for the 62 small, intracranial aneurysms that were treated with endovascular coiling.
| Follow-up imaging (N, %) | ||
| DSA | 44 | 71.0 |
| MR | 5 | 8.1 |
| CT | 4 | 6.5 |
| None | 9 | 14.5 |
| Follow-up, months (mean, range) | 8.98 | 0.06–40.96 |
| Occlusion at follow-up (N, %) | ||
| Not occluded | 0 | 0.0 |
| Complete (RR I) | 46 | 88.5 |
| Partial (RR II) | 6 | 11.5 |
| Enlarging remnant (RR III) | 0 | 0.0 |
| No aneurysm follow-up | 10 | |
| Recanalization | 4 | 7.7 |
| Coil compaction | 3 | 5.8 |
| Neck enlargement | 1 | 1.9 |
| Occlusion rate: RR I and II (%) | ||
| Overall | 92.3 | |
| Unruptured | 100 | |
| Ruptured | 88.6 | |
| Technical complications (N, %) | ||
| Coil protrusion | 5 | 8.1 |
| Thrombus formation | 6 | 9.7 |
| Intraoperative rupture | 3 | 4.8 |
| Clinical complications (N, %) | ||
| Infarction | 5 | 8.1 |
| Hemorrhage | 1 | 1.6 |
CT, computed tomography; DSA, digital subtraction angiography; MRA, magnetic resonance angiography; RR, Raymond–Roy occlusion class.
Outcomes
Mean follow-up for this cohort was 8.98 months (range: 0.06–40.96 months) (Table 4). Follow-up imaging primarily utilized DSA (44, 71%) with a minority of patients receiving MRA (5, 8.1%) or computed tomography angiography (CTA) (4, 6.5%). After index treatment, 57 patients had RROC class I occlusion and 5 patients (8.1%) had RROC class II occlusion (Table 5). Nine patients (14.5%) had no follow-up imaging and one patient had no aneurysm evaluation on follow-up. At last follow-up, RROC class I occlusion was seen in 46 (88.5%) aneurysms with class II occlusion in 6 (11.5%). Class III occlusion was not seen in any aneurysms. Recanalization occurred in four patients (7.7%) with coil compaction noted in three. The fourth recanalization occurred in one of the five patients with RROC class II on immediate posttreatment angiogram due to neck enlargement. 92.3% of patients were stably occluded with RROC class I or II occlusion at last follow-up; 100% of unruptured aneurysms and 88.6% of ruptured aneurysms achieved RROC class I or II occlusion. Only MicroVention Hydrogel and mixed coil brand-treated aneurysms had less than 100% occlusion (RROC I or II). Chi-square analysis of the association between follow-up RROC and coil type approached significance (p = .056). Average coil packing density appeared to differ between aneurysms that recanalized (43.7) compared to those that did not (34.7), although this difference was not statistically significant (p = .269). Recurrent aneurysms were significantly wider (3.2 vs. 2.4 mm, p < 0.001). Although all four cases of recanalization and all six cases of class II occlusion occurred in ruptured aneurysms, comparing these outcomes based upon rupture status did not reach significance (p = 0.179 and p = 0.08, respectively).
Table 5.
Postoperative and follow-up RROC and recanalization cases stratified by coil type.
| Postoperative RROC | Follow-up RROC | ||||
|---|---|---|---|---|---|
| Coil type | Class I | Class II | Class I | Class II | Recanalization |
| Balt Optima/OptiMAX Supersoft Coil System | 18 | 0 | 15 | 1 | 0 |
| MicroVention Hypersoft Platinum Coils | 1 | 1 | 0 | 1 | 0 |
| MicroVention Hydroframe and Hydrosoft Hydrogel Coils | 15 | 1 | 12 | 2 | 2 |
| Penumbra SMART COIL Extra Soft System | 11 | 1 | 11 | 0 | 0 |
| Avenir Coil System (Wallaby Medical) | 2 | 0 | 1 | 0 | 0 |
| Multiple coil brands | 10 | 2 | 7 | 2 | 2 |
Discussion
Despite advances in endovascular options for intracranial aneurysms, there remains no consensus on the ideal treatment for small aneurysms. In this study, we sought to analyze our experiences treating small aneurysms and provide an initial comparison between different coil types for small aneurysms.
In our study, 92.3% of patients achieved RROC class I or II occlusion status at last follow-up. No aneurysms were class III occlusion status and no posttreatment rebleeding occurred. Recanalization occurred in only 7.7%, primarily due to coil compaction and only in the ruptured aneurysm cohort. These are similar to the rates reported in other studies, with reported occlusion rates ranging from 69.6 to 97.2%.4,6,11,14,15 Similar to other studies, we found higher occlusion rates in unruptured aneurysms compared to ruptured aneurysms. 4 Although we are able to compare occlusion status between coil types, the low sample size is not powered to make significant conclusions. No recanalization was recorded in patients treated with Balt Optima/OptiMAX Supersoft or Penumbra SMART COIL Extra Soft coils. Case reports utilizing Optima coils (Balt) have shown similar coil packing density and occlusion.16,17 Similarly excellent occlusion rates (89.5–97.2%) have been shown for Penumbra coils in small aneurysms. 6 Bendok et al. 10 compared aneurysms treated with hydrogel coils to bare metal coils with complete occlusion in 68% (compared to 88.5% in our study) and recurrence rates of 4.4% compared to 15.4% in the traditional bare platinum coils. Our recanalization rate of 7.7% is close the reported range of 5.3–7.1%.4,6,11 The HEAT trial found that MicroVention Hydrogel coils were associated with higher coil packing density and lower recurrence rates when compared to bare metal coils. 10 Similar to this trial, we had low recurrence rates, in our study even with bare metal coils. While our average packing density was similar to that achieved by Hydrogel coils in the HEAT trial, our study used a more accurate method of aneurysm volume measurement. 10 All four recanalizations were in ruptured aneurysms treated with either hydrogel or “mixed” coil types and occurred between 4 and 13 months after treatment. Despite the high packing density and low recurrence reported for hydrogel coils, our series found a high recanalization rate in these small aneurysms, demonstrating the need for continued development of durable, small aneurysm-specific treatments.
Although we reported technical complications in 14 patients, this includes all patients with coil protrusion, thrombus formation (often as a consequence of stent-assisted coiling), and procedural rupture. Despite this, only a minor proportion of these resulted in clinical complications or lasting deficit. Iskandar et al. 5 found a similar rate of procedural rupture and mortality in small aneurysm treatment, but a lower morbidity compared to large aneurysms. Although not statistically significant, 11 of these technical complications occurred in ruptured aneurysms compared to only 3 in unruptured. Intraoperative rupture occurred in 4.8%, comparable to rates reported in other studies (4.1–7%), and all three intraoperative ruptures were in patients who presented with SAH.4,11,18,19 Only one of these ruptures resulted in significant clinical sequelae, likely due to the high frequency of balloon utilization allowing for quick control of hemorrhage.
Average aneurysm volume was significantly smaller in aneurysms with coil protrusion, and average aspect ratio was smaller in those with technical complications. This trend is supported by other studies finding higher complication rates in smaller aneurysms5,20 and reflects concerns about endovascular treatment for small aneurysms: the small volume of the aneurysm sac is difficult to safely fill without coils rupturing the dome or protruding coils from the neck.21,22 Previous studies have found that high aspect ratio indicates greater rupture risk; therefore, aneurysms with smaller aspect ratios or larger necks are protected from rupture. 23 We found a smaller aspect ratio in aneurysms with technical complications, which may be related to the difficulty in fitting coils into an aneurysm that is both small and wide-necked. However, the overall rates of complications and aneurysm outcomes in this study are consistent with series of larger aneurysms.4,11,18,19 Here, we clearly demonstrate the possibility of excellent aneurysm outcomes achieved with a reasonable safety profile and no episodes of rebleeding.
Previously, coil packing densities over 20% were thought to decrease chance of aneurysm recanalization with the caveat that packing sufficient coils to reach a high density could rupture the aneurysm.24,25 After a recent systematic review by Hassankhani et al., 26 the impact of coil packing density on aneurysm recanalization seems unclear. The average packing densities we achieved in aneurysms with class I and class II occlusion were similar (35.6 and 36.3, respectively). Advancements in coils, such as complex 3D configurations and coatings, are especially important for small aneurysm treatment, as they increase the density the same number of coils can achieve without increasing risk of rupture. 10 There have been previous studies demonstrating the efficacy of these new coil types in small aneurysms;6,10,12 however, only one study has compared more than two coil types 13 and our study is the first to do so for small aneurysms. Increasing coil softness could theoretically lead to increase in recurrence given the possibility of coil compaction and recanalization. However, despite the use of mostly small, “soft” coils, we did not see rates of complete occlusion or recanalization to be worse than previously reported studies of larger aneurysms. 5 That being said, the average coil packing density in this study was relatively high in the majority of cases than when compared to the literature. Our method of measuring aneurysm volume, which is used for packing density calculations, is likely more accurate compared to published studies, giving a higher-than-expected density achieved in our study. 10 Additionally, our use of balloon assistance and experience in aneurysm coiling allow for us to achieve a high standard of packing density, even in ruptured aneurysms, with a relatively low number of intraprocedural ruptures. When comparing effect of coil type on complete occlusion, the difference almost reached significance. Notably, no recanalization occurred in aneurysms treated with Optima (Balt) or Penumbra coil systems, despite all coils being used to treat both ruptured and unruptured aneurysms.
Limitations
As with all retrospective studies, we are limited by the available population and the chart data available for collection. Despite a relatively small cohort size, only nine patients received no follow-up imaging and characteristics were well distributed across patients for comparison. Given the variability in rupture status, aneurysm size, and location, it may be difficult to draw generalizable conclusions.
Conclusions
Recent advances in coil technology have enhanced the ability of interventionalists to treat small aneurysms. High occlusion rates are achievable, especially in unruptured aneurysms, with coil type and packing density suggesting an association with complete occlusion. Technical complication rates may be notable, influenced by factors including aspect ratio and aneurysm volume; however, they can be mitigated to prevent lasting clinical complications and do not prevent stable aneurysm occlusion.
Footnotes
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Ethical approval: Ethical approval was received by the Institutional Review Board (IRB 22-0748) on November 17, 2022, including a waiver of informed consent.
Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.
ORCID iDs: Sabrina L Begley https://orcid.org/0000-0003-2621-1968
Timothy G White https://orcid.org/0000-0002-3604-4334
Kevin A Shah https://orcid.org/0000-0003-0896-2266
Justin Turpin https://orcid.org/0000-0002-3686-2695
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