Long-Term Outcomes of Surgical Clipping of Woven EndoBridge-Eligible Middle Cerebral Artery Bifurcation Aneurysms

Operative Neurosurgery 30:18–25, 2026

This clinical study evaluates long-term outcomes of microsurgical clipping for middle cerebral artery (MCA) wide-neck bifurcation aneurysms that meet radiographic criteria for treatment with the Woven EndoBridge (WEB) device. Using a retrospective review of a prospectively maintained registry, the authors compare functional outcomes, complication rates, recurrence, and retreatment against published WEB and clipping cohorts.

Results show high surgical efficacy: 99% treatment success, 94.1% of unruptured cases achieving final mRS ≤2, a 4.9% morbidity rate, and 0% mortality, with lower retreatment and higher complete occlusion rates than reported WEB series. The authors conclude microsurgical clipping remains a reliable option for MCA WNBAs and recommend location-specific subgroup analyses in future WEB studies.

Microsurgical Clipping Outcomes: Surgical clipping of WEB-eligible middle cerebral artery (MCA) wide-necked bifurcation aneurysms (WNBAs) achieved a 99% treatment success rate, 4.9% morbidity, 0% mortality, and 94.1% good functional outcomes (mRS ≤2) in unruptured cases, with low recurrence and retreatment rates.

Comparison to WEB Device: Clipping resulted in higher complete occlusion rates, lower retreatment rates, and lower thromboembolic complication rates compared to endovascular treatment with the Woven EndoBridge (WEB) device for MCA WNBAs.

Functional Outcomes: Both ruptured and unruptured aneurysms treated surgically showed excellent or improved functional status at follow-up, with 91.8% of unruptured and 94.1% of ruptured cases experiencing stable or improved mRS scores.

Complication Profile: Thromboembolic complications occurred in 5.9% of unruptured cases, with permanent neurological deficits in 4.9% and no surgical mortality; intraoperative rupture was rare (2.0%).

Limitations of WEB Evidence: Most WEB studies pooled multiple aneurysm locations, making it difficult to assess location-specific efficacy; at the MCA, WEB showed higher retreatment and thromboembolic rates than clipping, and lower rates of complete occlusion.

Treatment Selection: MCA aneurysms are often suitable for surgical clipping due to their accessible location and favorable anatomy, especially at experienced centers, supporting a “clip-first” approach for many MCA WNBAs.

Study Limitations: Findings are based on a retrospective, single-center cohort at a high-volume academic institution, limiting generalizability and direct comparison to randomized or multicenter WEB trials.

Clinical Recommendation: Both clipping and WEB are effective for MCA WNBAs, but surgical clipping may offer superior durability and occlusion; treatment choice should be individualized through shared decision-making, not solely based on minimally invasive appeal.

Microsurgical clipping and endovascular management of unruptured anterior circulation aneurysms: how age, frailty, and comorbidity indexes influence outcomes

J Neurosurg 138:922–932, 2023

Frailty is one of the important factors in predicting the outcomes of surgery. Many surgical specialties have adopted a frailty assessment in the preoperative period for prognostication; however, there are limited data on the effects of frailty on the outcomes of cerebral aneurysms. The object of this study was to find the effect of frailty on the surgical outcomes of anterior circulation unruptured intracranial aneurysms (UIAs) and compare the frailty index with other comorbidity indexes.

METHODS A retrospective study was performed utilizing the National Inpatient Sample (NIS) database (2016–2018). The Hospital Frailty Risk Score (HFRS) was used to assess frailty. On the basis of the HFRS, the whole cohort was divided into low-risk (0–5), intermediate-risk (> 5 to 15), and high-risk (> 15) frailty groups. The analyzed outcomes were nonhome discharge, complication rate, extended length of stay, and in-hospital mortality.

RESULTS In total, 37,685 patients were included in the analysis, 5820 of whom had undergone open surgical clipping and 31,865 of whom had undergone endovascular management. Mean age was higher in the high-risk frailty group than in the low-risk group for both clipping (63 vs 55.4 years) and coiling (64.6 vs 57.9 years). The complication rate for open surgical clipping in the high-risk frailty group was 56.1% compared to 0.8% in the low-risk group. Similarly, for endovascular management, the complication rate was 60.6% in the high-risk group compared to 0.3% in the low-risk group. Nonhome discharges were more common in the high-risk group than in the low-risk group for both open clipping (87.8% vs 19.7%) and endovascular management (73.1% vs 4.4%). Mean hospital charges for clipping were $341,379 in the high-risk group compared to $116,892 in the low-risk group. Mean hospital charges for coiling were $392,861 in the high-risk frailty group and $125,336 in the low-risk group. Extended length of stay occurred more frequently in the highrisk frailty group than in the low-risk group for both clipping (82.9% vs 10.7%) and coiling (94.2% vs 12.7%). Frailty had higher area under the receiver operating characteristic curve values than those for other comorbidity indexes and age in predicting outcomes.

CONCLUSIONS Frailty affects surgical outcomes significantly and outperforms age and other comorbidity indexes in predicting outcome. It is imperative to include frailty assessment in preoperative planning.

Endovascular therapy versus microsurgical clipping of unruptured wide-neck aneurysms: a prospective multicenter study with propensity score analysis

J Neurosurg 137:352–359, 2022

Numerous techniques have been developed to treat wide-neck aneurysms (WNAs), each with different safety and efficacy profiles. Few studies have compared endovascular therapy (EVT) with microsurgery (MS). The authors’ objective was to perform a prospective multicenter study of a WNA registry using rigorous outcome assessments and to compare EVT and MS using propensity score analysis (PSA).

METHODS Unruptured, saccular, not previously treated WNAs were included. WNA was defined as an aneurysm with a neck width ≥ 4 mm or a dome-to-neck ratio (DTNR) < 2. The primary outcome was modified Rankin Scale (mRS) score at 1 year after treatment (good outcome was defined as mRS score 0–2), as assessed by blinded research nurses and compared with PSA. Angiographic outcome was assessed using the Raymond scale with core laboratory review (adequate occlusion was defined as Raymond scale score 1–2).

RESULTS The analysis included 224 unruptured aneurysms in the EVT cohort (n = 140) and MS cohort (n = 84). There were no differences in baseline demographic characteristics, such as proportion of patients with good baseline mRS score (94.3% of the EVT cohort vs 94.0% of the MS cohort, p = 0.941). WNA inclusion criteria were similar between cohorts, with the most common being both neck width ≥ 4 mm and DTNR < 2 (50.7% of the EVT cohort vs 50.0% of the MS cohort, p = 0.228). More paraclinoid (32.1% vs 9.5%) and basilar tip (7.1% vs 3.6%) aneurysms were treated with EVT, whereas more middle cerebral artery (13.6% vs 42.9%) and pericallosal (1.4% vs 4.8%) aneurysms were treated with MS (p < 0.001). EVT aneurysms were slightly larger (p = 0.040), and MS aneurysms had a slightly lower mean DTNR (1.4 for the EVT cohort vs 1.3 for the MS cohort, p = 0.010). Within the EVT cohort, 9.3% of patients underwent stand-alone coiling, 17.1% balloon-assisted coiling, 34.3% stent-assisted coiling, 37.1% flow diversion, and 2.1% PulseRider-assisted coiling. Neurological morbidity secondary to a procedural complication was more common in the MS cohort (10.3% vs 1.4%, p = 0.003). One-year mRS scores were assessed for 218 patients (97.3%), and no significantly increased risk of poor clinical outcome was found for the MS cohort (OR 2.17, 95% CI 0.84–5.60, p = 0.110). In an unadjusted direct comparison, more patients in the EVT cohort achieved a good clinical outcome at 1 year (93.4% vs 84.1%, p = 0.048). Final adequate angiographic outcome was superior in the MS cohort (97.6% of the MS cohort vs 86.5% of the EVT cohort, p = 0.007).

CONCLUSIONS Although the treatments for unruptured WNA had similar clinical outcomes according to PSA, there were fewer complications and superior clinical outcome in the EVT cohort and superior angiographic outcomes in the MS cohort according to the unadjusted analysis. These results may be considered when selecting treatment modalities for patients with unruptured WNAs.

Microsurgical clipping of middle cerebral artery aneurysms: preoperative planning using virtual reality to reduce procedure time

Neurosurg Focus 51 (2):E12, 2021

The authors sought to evaluate the impact of virtual reality (VR) applications for preoperative planning and rehearsal on the total procedure time of microsurgical clipping of middle cerebral artery (MCA) ruptured and unruptured aneurysms compared with standard surgical planning.

METHODS A retrospective review of 21 patients from 2016 to 2019 was conducted to determine the impact on the procedure time of MCA aneurysm clipping after implementing VR for preoperative planning and rehearsal. The control group consisted of patients whose procedures were planned with standard CTA and DSA scans (n = 11). The VR group consisted of patients whose procedures were planned with a patient-specific 360° VR (360VR) model (n = 10). The 360VR model was rendered using CTA and DSA data when available. Each patient was analyzed and scored with a case complexity (CC) 5-point grading scale accounting for aneurysm size, incorporation of M2 branches, and aspect ratio, with 1 being the least complex and 5 being the most complex. The mean procedure times were compared between the VR group and the control group, as were the mean CC score between the groups. Comorbidities and aneurysm conduction (ruptured vs unruptured) were also taken into consideration for the comparison.

RESULTS The mean CC scores for the control group and VR group were 2.45 ± 1.13 and 2.30 ± 0.48, respectively. CC was not significantly different between the two groups (p = 0.69). The mean procedure time was significantly lower for the VR group compared with the control group (247.80 minutes vs 328.27 minutes; p = 0.0115), particularly for the patients with a CC score of 2 (95% CI, p = 0.0064). A Charlson Comorbidity Index score was also calculated for each group, but no statistical significance was found (VR group, 2.8 vs control group, 1.8, p = 0.14).

CONCLUSIONS In this study, usage of 360VR models for planning the craniotomy and rehearsing with various clip sizes and configurations resulted in an 80-minute decrease in procedure time. These findings have suggested the potential of VR technology in improving surgical efficiency for aneurysm clipping procedures regardless of complexity, while making the procedure faster and safer.

Small intracranial aneurysms in the Barrow Ruptured Aneurysm Trial (BRAT)

Acta Neurochirurgica (2021) 163:123–129

Treatment of small ruptured aneurysms (SRAs) remains controversial, with literature reporting difficulty with endovascular versus microsurgical approaches. This paper analyzes outcomes after endovascular coiling and microsurgical clipping among patients with SRAs prospectively enrolled in the Barrow Ruptured Aneurysm Trial (BRAT).

Method All BRAT patients were included in this study. Patient demographics, aneurysm size, aneurysm characteristics, procedure-related complications, and outcomes at discharge and at 1-year and 6-year follow-up were evaluated. A modified Rankin scale (mRS) score > 2 was considered a poor outcome.

Results Of 73 patients with SRAs, 40 were initially randomly assigned to endovascular coiling and 33 to microsurgical clipping. The rate of treatment crossover was significantly different between coiling and clipping; 25 patients who were assigned to coiling crossed over to clipping, and no clipping patients crossed over to coiling (P < 0.001). Among SRA patients, 15 underwent coiling and 58 underwent clipping; groups did not differ significantly in demographic characteristics or aneurysm type (P ≥ 0.11). Mean aneurysm diameter was significantly greater in the endovascular group (3.0 ± 0.3 vs 2.6 ± 0.6; P = 0.02). The incidence of procedure-related complications was similar for endovascular and microsurgical treatments (odds ratio [95% confidence interval], 1.0 [0.1–10.0], P = 0.98). Both groups had comparable overall outcome (mRS score > 2) at discharge and 1-year and 6-year follow-up (P = 0.48 and 0.73, respectively).

Conclusions Most SRA patients in the BRAT underwent surgical clipping, with a high rate of crossover from endovascular approaches. Endovascular treatment was equivalent to surgical clipping with regard to procedure-related complications and neurologic outcomes.

Microsurgical clipping of ophthalmic artery aneurysms

J Neurosurg 129:1511–1521, 2018

While most paraclinoid aneurysms can be clipped with excellent results, new postoperative visual deficits are a concern. New technology, including flow diverters, has increased the popularity of endovascular therapy. However, endovascular treatment of paraclinoid aneurysms is not without procedural risks, is associated with higher rates of incomplete aneurysm occlusion and recurrence, and may not address optic nerve compression symptoms that surgical debulking can. The increasing endovascular management of paraclinoid aneurysms should be justified by comparisons to surgical benchmarks. The authors, therefore, undertook this study to define patient, visual, and aneurysm outcomes in the most common type of paraclinoid aneurysm: ophthalmic artery (OphA) aneurysms.

METHODS Results from microsurgical clipping of 208 OphA aneurysms in 198 patients were retrospectively reviewed. Patient demographics, aneurysm morphology (size, calcification, etc.), clinical characteristics, and patient outcomes were recorded and analyzed.

RESULTS Despite 20% of these aneurysms being large or giant in size, complete aneurysm occlusion was accomplished in 91% of 208 cases, with OphA patency preserved in 99.5%. The aneurysm recurrence rate was 3.1% and the retreatment rate was 0%. Good outcomes (modified Rankin Scale score 0–2) were observed in 96.2% of patients overall and in all 156 patients with unruptured aneurysms. New visual field defects (hemianopsia or quadrantanopsia) were observed in 8 patients (3.8%), decreased visual acuity in 5 (2.4%), and monocular blindness in 9 (4.3%). Vision improved in 9 (52.9%) of the 17 patients with preoperative visual deficits.

CONCLUSIONS The most important risk associated with clipping OphA aneurysms is a new visual deficit. Meticulous microsurgical technique is necessary during anterior clinoidectomy, aneurysm dissection, and clip application to optimize visual outcomes, and aggressive medical management postoperatively might potentially decrease the incidence of delayed visual deficits. As the results of endovascular therapy and specifically flow diverters become known, they warrant comparison with these surgical benchmarks to determine best practices.

Cotton-clipping and cotton-augmentation for aneurysms

cotton-clipping-and-cotton-augmentation-for-aneurysms

J Neurosurg 125:720–729, 2016

To address the challenges of microsurgically treating broad-based, frail, and otherwise complex aneurysms that are not amenable to direct clipping, alternative techniques have been developed. One such technique is to use cotton to augment clipping (“cotton-clipping” technique), which is also used to manage intraoperative aneurysm neck rupture, and another is to reinforce unclippable segments or remnants of aneurysm necks with cotton (“cottonaugmentation” technique). This study reviews the natural history of patients with aneurysms treated with cotton-clipping and cotton-augmentation techniques.

Methods The authors queried a database consisting of all patients with aneurysms treated at Barrow Neurological Institute in Phoenix, Arizona, between January 1, 2004, and December 31, 2014, to identify cases in which cotton-clipping or cotton-augmentation strategies had been used. Management was categorized as the cotton-clipping technique if cotton was used within the blades of the aneurysm clip and as the cotton-clipping technique if cotton was used to reinforce aneurysms or portions of the aneurysm that were unclippable due to the presence of perforators, atherosclerosis, or residual aneurysms. Data were reviewed to assess patient outcomes and annual rates of aneurysm recurrence or hemorrhage after the initial procedures were performed.

Results The authors identified 60 aneurysms treated with these techniques in 57 patients (18 patients with ruptured aneurysms and 39 patients with unruptured aneurysms) whose mean age was 53.1 years (median 55 years; range 24–72 years). Twenty-three aneurysms (11 cases of subarachnoid hemorrhage) were treated using cotton-clipping and 37 with cotton-augmentation techniques (7 cases of subarachnoid hemorrhage). In total, 18 patients presented with subarachnoid hemorrhage. The mean Glasgow Outcome Scale (GOS) score at the time of discharge was 4.4. At a mean follow-up of 60.9 ± 35.6 months (median 70 months; range 10–126 months), the mean GOS score at last follow-up was 4.8. The total number of patient follow-up years was 289.4. During the follow-up period, none of the cotton-clipped aneurysms increased in size, changed in configuration, or rebled. None of the patients experienced early rebleeding. The annual hemorrhage rate for aneurysms treated with cotton-augmentation was 0.52% and the recurrence rate was 1.03% per year. For all patients in the study, the overall risk of hemorrhage was 0.35% per year and the annual recurrence rate was 0.69%.

Conclusions Cotton-clipping is an effective and durable treatment strategy for intraoperative aneurysm rupture and for management of broad-based aneurysms. Cotton-augmentation can be safely used to manage unclippable or partially clipped intracranial aneurysms and affords protection from early aneurysm re-rupture and a relatively low rate of late rehemorrhage.

Impact of Indocyanine Green Videoangiography on Rate of Clip Adjustments Following Intraoperative Angiography

Essentials in intraoperative indocyanine green videoangiography assessment for intracranial aneurysm surgery

Neurosurgery 75:437–444, 2014

Intraoperative angiography (IA) is used to evaluate the adequacy of clip reconstruction of intracranial aneurysms. Alternative imaging such as indocyanine green videoangiography (ICG-VA) has been proposed. The additional benefit of ICG-VA when IA is routinely used has not been previously determined.

OBJECTIVE: To report our experience with the use of ICG-VA in combination with IA vs IA alone.

METHODS: We retrospectively reviewed cases of aneurysm clipping during a 21-month period by a single surgeon in which ICG-VA was performed after clip reconstruction prior to IA, or IA alone was performed to verify optimal clipping. Records were reviewed for age, sex, race, length of stay, rupture status, Hunt and Hess grade, aneurysm size, location, and temporary clipping. Intraoperative decision making was determined for each group.

RESULTS: Ninety-four patients who underwent 97 craniotomies for 128 aneurysms met inclusion criteria for this study. ICG-VA1IA was performed in 37 craniotomies; IA alone was performed for 60 craniotomies. Baseline characteristics were similar with the exception that median aneurysm size was slightly larger in the ICG-VA group (5.6 mm vs 4.3 mm, P = .04). ICG-VA produced 4 false negatives, which required clip adjustments following IA (10.8%), vs 7 patients (11.7%) in the IA-alone group requiring clip adjustments (P = .897).

CONCLUSION: When IA is routinely performed, the additional use of ICG-VA does not eliminate the need for post-IA clip adjustments owing to the possibility of false negatives. When ICG-VA suggests optimal clipping, but is followed by IA, the rate of post-IA modifications in this study did not differ significantly than if ICG-VA had not been performed.

Microsurgical clipping of true posterior communicating artery aneurysms

Acta Neurochir (2012) 154:1707–1710

“True” posterior communicating artery (PCOM) aneurysms are rare variants in which the aneurysm arises solely from the PCOM rather than the junction of the internal carotid artery and the PCOM.

Methods It is critical to note that for true PCOM aneurysms, the neck arises distal to the origin of the PCOM and therefore lies in what is traditionally an intra-operative blind spot. The PCOM must be followed posteriorly to visualise the aneurysm neck for microsurgical clipping.

Conclusions A thorough pre-operative understanding of this unique anatomy is essential in minimising morbidity associated with microsurgical clipping of this aneurysm configuration.

Microsurgical Clipping of Posterior Communicating Artery Aneurysms in the Endovascular Era

Neurosurgery 71:285–295, 2012 DOI: 10.1227/NEU.0b013e318256c3eb

Many neurosurgeons feel competent clipping posterior communicating artery (PCoA) aneurysms and include this lesion in their practice. However, endovascular therapy removes simple aneurysms that would have been easiest to clip with the best results. What remains are aneurysms with complex anatomy and technical challenges that are not well described.

OBJECTIVE: A contemporary surgical series with PCoA aneurysms is reviewed to define the patients, microsurgical techniques, and outcomes in current practice. METHODS: A total of 218 patients had 218 PCoA aneurysms that were treated microsurgically during an 11-year period. Complexities influencing aneurysm management included (1) large/giant size; (2) fetal posterior cerebral artery; (3) previous coiling; (4) anterior clinoidectomy; (5) adherence of the anterior choroidal artery (AChA); (6) intraoperative aneurysm rupture; (7) complex clipping; and (8) atherosclerotic calcification.

RESULTS: Simple PCoA aneurysms were encountered in 113 patients (51.8%) and complex aneurysms in 105 (48.2%). Adherent AChA (13.8%) and intraoperative rupture (11.5%) were the most common complexities. Simple aneurysms had favorable outcomes in 86.6% of patients, whereas aneurysms with 1 or multiple complexities had favorable outcomes in 78.2% and 75.0%, respectively. Intraoperative rupture (P , .01), large/giant size (P = .04), and complex clipping (P = .05) were associated with increased neurological worsening.

CONCLUSION: Because endovascular therapy alters the surgical population, neurosurgeons should recalibrate their expectations with this once straightforward aneurysm. The current mix of PCoA aneurysms requires advanced techniques including clinoidectomy, AChA microdissection, complex clipping, and facility with intraoperative rupture. Microsurgery is recommended for recurrent aneurysms after coiling, complex branches, aneurysms causing oculomotor nerve palsy, multiple aneurysms, and patients with hematomas.