Microsurgical Clipping Research Articles

National trends in surgical treatment and clinical outcomes among patients with aneurysmal subarachnoid hemorrhage in the Republic of Korea.

In this study, changes in treatment methods and patient prognosis were analyzed using a Korean nationwide medical insurance information database. Patients with subarachnoid hemorrhage who received surgical treatment for cerebral aneurysm from 2005 to 2020 were included. The specific surgery type was classified using the surgical code and according to whether stents were used. Yearly trends in mortality rates and poor prognosis, using tracheostomy as proxy, were analyzed by a simple regression analysis. A multistep logistic regression analysis was performed to evaluate the risk factors of mortality and poor prognosis. Overall, 83,587 patients were included. Females were predominant (64.5%). Microsurgical clip usage rate decreased by approximately two-thirds from 78.8% in 2005 to 24.4% in 2020. Contrarily, endovascular treatment proportion gradually increased, and stent-assisted coil embolization rate surpassed microsurgical clip usage rate in 2020 (24.6% vs. 24.4%). In the multivariate analysis, endovascular treatment correlated positively with 3-month mortality (hazard ratio [HR]: 1.13, 95% confidence interval [CI]: 1.07-1.19, P<0.0001), although correlated negatively with poor prognosis (tracheostomy) (HR: 0.93, 95% CI: 0.89-0.98, P=0.0050). According to the treatment trend analysis, during the 16 years studied, for patients with subarachnoid hemorrhage due to ruptured cerebral aneurysm, the endovascular treatment rate increased rapidly and stent-assisted coil embolization rate surpassed that of microsurgical clip ligation. Diversification of treatment methods has led to a decrease in mortality and improved prognosis.

Subtemporal Approach for the Treatment of Ruptured and Unruptured Distal Basilar Artery Aneurysms: Is There a Contemporary Use?

Distal basilar artery aneurysms (DBAs) are high-risk lesions for which endovascular treatment is preferred because of their deep location, yet indications for open clipping nonetheless remain. The subtemporal approach allows for early proximal control and direct visualization of critical posterior perforating arteries, especially for posterior-projecting aneurysms. Our objective was to describe our clinical experience with the subtemporal approach for clipping DBAs in the evolving endovascular era. This was a retrospective, single-institution case series of patients with DBAs treated with microsurgery over a 21-year period (2002-2023). Demographic, clinical, and surgical data were collected for analysis. Twenty-seven patients underwent clipping of 11 ruptured and 16 unruptured DBAs with a subtemporal approach (24 female; mean age 53 years). Ten patients had expanded craniotomies for treatment of additional aneurysms. The aneurysm occlusion rate was 100%. Good neurological outcomes as defined by the modified Rankin Scale score ≤2 and Glasgow Outcome Scale score ≥4 were achieved in 21/27 patients (78%). Two patients died before hospital discharge, one from vasospasm-induced strokes and another from an intraoperative myocardial infarction. These results demonstrate that microsurgical clip ligation of DBAs using the subtemporal approach remains a viable option for complex lesions not amenable to endovascular management.

Transcarotid flow reversal for proximal control during cerebral aneurysm clip reconstruction: illustrative case.

Paraclinoid aneurysms can pose an operative challenge during clip reconstruction, given the complex surrounding anatomy and the aneurysmal tendency to maintain turgor despite standard approaches to proximal control. This report demonstrates the use of intraoperative retrograde arteriovenous shunting with the transcarotid artery revascularization (TCAR) system to assist in the safe clip reconstruction of an irregular paraclinoid aneurysm. A 33-year-old woman presented with perimesencephalic subarachnoid hemorrhage and was found to have an incidental 9-mm ophthalmic aneurysm. Coil embolization was not successful. During microsurgical clip reconstruction, the left common carotid artery was exposed to allow for proximal control as well as transcarotid arterial sheath placement. Flow reversal was instituted throughout the aneurysm dissection and clipping, with a visible softening of the aneurysm. Intraoperative angiography confirming successful clip reconstruction was performed utilizing the TCAR sheath. The case was complicated by the development of cerebrospinal fluid rhinorrhea postoperatively, requiring surgical repair. The patient has since made a complete recovery. Transcarotid flow reversal utilizing the TCAR system has potential for use in the surgical treatment of paraclinoid aneurysms, as it may aid in softening the aneurysm for safer dissection and clip reconstruction, protect against aneurysm-associated emboli, and provide an avenue for intraoperative angiography. https://thejns.org/doi/10.3171/CASE24330.

Maximizing the Carotid-Oculomotor Triangle and Oculomotor-Trochlear Corridor for Microsurgical Clipping of a Large Wide-Neck Low-Lying Basilar Apex Aneurysm: 2-Dimensional Operative Video.

Maximizing the Carotid-Oculomotor Triangle and Oculomotor-Trochlear Corridor for Microsurgical Clipping of a Large Wide-Neck Low-Lying Basilar Apex Aneurysm: 2-Dimensional Operative Video.

Machine Learning-Based Prediction of Clinical Outcomes in Microsurgical Clipping Treatments of Cerebral Aneurysms.

Background: This study investigates the application of Machine Learning techniques to predict clinical outcomes in microsurgical clipping treatments of cerebral aneurysms, aiming to enhance healthcare processes through informed clinical decision making. Methods: Relying on a dataset of 344 patients' preoperative characteristics, various ML classifiers were trained to predict outcomes measured by the Glasgow Outcome Scale (GOS). The study's results were reported through the means of ROC-AUC scores for outcome prediction and the identification of key predictors using SHAP analysis. Results: The trained models achieved ROC-AUC scores of 0.72 ± 0.03 for specific GOS outcome prediction and 0.78 ± 0.02 for binary classification of outcomes. The SHAP explanation analysis identified intubation as the most impactful factor influencing treatment outcomes' predictions for the trained models. Conclusions: The study demonstrates the potential of ML for predicting surgical outcomes of ruptured cerebral aneurysm treatments. It acknowledged the need for high-quality datasets and external validation to enhance model accuracy and generalizability.

Effect of External Ventricular Drainage on Shunt-Dependent Hydrocephalus and Prognosis After Microsurgical Clipping in Patients with Poor-Grade Aneurysmal Subarachnoid Hemorrhage

In poor-grade aneurysm subarachnoid hemorrhage (PaSAH), the use of external ventricular drainage (EVD) may be closely related to the occurrence of shunt-dependent hydrocephalus (SDHC). The purpose of this study was to investigate the effect of EVD on SDHC and prognosis after microsurgical clipping patients with PaSAH. The clinical data of 99 patients with PaSAH admitted to the 904th Hospital of PLA from October 2011 to December 2020 were analyzed retrospectively. Univariate and multivariate logistic regression analyses were used to clarify the relationship between EVD implantation and its drainage volume and SDHC after PaSAH. ROC curves were plotted to compare the prognostic efficiency of different drainage volumes on SDHC. Modified possion regression analysis was used to determine the effect of SDHC on prognosis after PaSAH. EVD implantation increased the risk of SDHC (OR=6.715, 95% CI 1.120-40.248, P=0.037). The increased drainage volume on day 1, mean daily drainage volume within 2 days, and average within 3 days increased the risk of SDHC. EVD drainage volume on the first postoperative day has a good predictive ability for SDHC after PaSAH, with an AUC of 0.829 (95% CI 0.731 - 0.928), the optimal cut-off value was 208 ml, with a sensitivity of 79.4%, a specificity of 81.6%, and a Youden index of 0.61. The occurrence of SDHC after aneurysm clipping significantly increases the risk of poor prognosis of PaSAH. EVD implantation is an independent risk factor for SDHC after PaSAH, and a large drainage volume in the first 3 days after EVD implantation is an independent risk factor for SDHC after PaSAH. The drainage volume on the first day after surgery is the best predictor of SDHC after PaSAH. SDHC after PaSAH is the strongest independent risk factor for poor prognosis and prolongs hospital stay.

Keyhole Alternatives to Pterional Craniotomy for the Microsurgical Clipping of Anterior Circulation Aneurysms: Technical Pearls, Surgical Results, and a Case Selection Algorithm.

Despite a recent surge in keyhole approaches to aneurysm clipping, only few studies have compared these approaches, and none have laid any foundation or roadmap for surgeons newly venturing into these procedures. To report a single surgeon's experience of multiple keyhole approaches to these aneurysms, and to highlight the case selection algorithm, technical nuances, and surgical results. Twenty-four patients (25 aneurysms) underwent aneurysm clipping using either a mini-pterional approach (MPA), lateral supraorbital approach (LSO), or a supraorbital keyhole approach (SOKHA). Intraoperative premature rupture, adequacy of clipping, and immediate postoperative and long-term functional outcomes were recorded. All but five patients presented with ruptured aneurysms (Hunt and Hess grade 1 in 12 patients, grade 2 in 5 patients, and grade 3 in 2 patients). The anterior communicating artery (A-Comm; n = 14, 56%) was most frequently involved with aneurysms. The MPA was most frequently employed (n = 11, 45.8%), followed by the LSO (n = 9, 37.5%) and the SOKHA (n = 4, 16.7%). An intraoperative rupture (total n = 5, 20.8%) was most frequently seen in the SOKHA group (50%) and the only case of inadequate aneurysm clipping resulted from inadequate clipping ergonomics during the SOKHA for A-Comm aneurysm. Major complications occurred in the supraorbital approaches (one each in the LSO and SOKHA). Irrespective of the approach used, the long-term outcomes were excellent. In properly selected patients, keyhole approaches-particularly the MPA and the LSO-can provide excellent surgical outcomes. The learning curve in the SOKHA is steeper. A pragmatic case selection algorithm is proposed.

Incidence and Characteristics of Cerebral Infarction After Microsurgical Clipping of Unruptured Anterior Circulation Cerebral Aneurysms: Diffusion-Weighted Imaging-Based Analysis of 600 Patients.

Postclipping cerebral infarction (PCI) remains a major concern after treatment for unruptured intracranial aneurysms (UIAs). However, studies of microsurgical clipping based on diffusion-weighted imaging are limited. We aimed to present the incidence, risk factors, and types of PCI and its radiological and clinical characteristics. This was a retrospective single-center study in which patients were scheduled to undergo microsurgical clipping for anterior circulation UIAs. The overall incidence and risk factors were calculated. Based on the operation and relevant artery, we categorized PCI on diffusion-weighted imaging into 4 types and presented their radiological and clinical characteristics. We reviewed the radiological and clinical data of 605 patients. The overall incidence of PCI was 16.7% (101/605), of which asymptomatic infarction was 14.9% (90/605) and symptomatic infarction was 1.8% (11/605). Hypertension (adjusted odds ratio [aOR], 2.258; 95% confidence interval [CI]: 1.330-3.833), temporary clipping (aOR, 1.690; 95% CI: 1.034-2.760), multiple aneurysm locations (aOR, 1.832; 95% CI: 1.084-3.095), and aneurysm dome size (aOR, 1.094; 95% CI: 1.006-1.190) were independent risk factors for PCI. Type II (perianeurysmal perforator) infarction was the most common type of PCI (48.6%) and the most common cause of symptomatic infarction (72.7%). Types II and III (distal embolic) infarctions correlated with atherosclerotic changes in the aneurysm wall and temporary clipping (62.4% and 70.6%, respectively). The type IV (unrelated) infarction group had a higher incidence of systemic atherosclerosis (55%). Microsurgical clipping is a safe and viable option for the treatment of anterior circulation UIAs. However, modification of the surgical technique, preoperative radiological assessment, and patient selection are required to reduce the incidence of PCI.

Lateral Supraorbital Approach for Microsurgical Clipping of Recurrent Ruptured Fetal Posterior Communicating Artery Aneurysm Initially Treated With Woven Endobridge Embolization and Flow Diversion: 2-Dimensional Operative Video

Fetal posterior communicating artery (PComA) is a variant of the cerebral vasculature. 1 Woven endobridge (WEB) embolization carries a good safety profile as treatment for ruptured wide neck PComA aneurysms, without the need for antiplatelet therapy. However, the reported occlusion rates are not optimal. 2 Flow diversion is suboptimal in treating aneurysms originating from fetal PComA. 3 Here we present a case of a 78-year-old female patient with a history of ruptured right fetal PComA aneurysm with wide base. It was initially treated with WEB embolization at an outside hospital. After WEB implantation, the initial follow-up of cerebral angiogram (6 months later) demonstrated a neck recurrence measuring 6 × 3 mm. Approximately 1 year after the initial treatment, pipeline embolization was performed and patient was placed on antiplatelet therapy since. Follow-up images demonstrated a 6 mm × 4 mm persistent neck remnant. Her care was transferred to our institution. Cerebral angiogram obtained 36 months post-WEB implantation showed growth of the neck remnant measuring 9 × 8.5 mm. The WEB device was found to be folded in the aneurysmal fundus. Given this was a growing recurrent previously ruptured fetal PComA aneurysm with a pipeline stent in the internal carotid artery the decision was made to retreat with microsurgical clipping; carotid access at the neck was required for proximal control. We achieved complete aneurysm obliteration through a minimal invasive approach. The patient gave informed consent for surgery and video recording. Institutional Review Board approval was deemed unnecessary.

Improved rates of postoperative ischemia, completeness of aneurysm occlusion and neurological deficits in elective clipping of anterior circulation aneurysms over the past 20 years – association with technical improvements

Background/PurposeSeveral periprocedural adjuncts for elective surgical aneurysm treatment have been introduced over the last 20 years to increase safety and efficacy. Besides the introduction of IONM in the late-1990s, ICG-videoangiography (ICG-VAG) since the mid-2000s and intraoperative CT-angiography/-perfusion (iCT-A/-P) since the mid-2010s are available. We aimed to clarify whether the introduction of ICG-VAG and iCT-A/-P resulted in our department in a stepwise improvement in the rate of radiologically detected postoperative ischemia, complete aneurysm occlusion and postoperative new deficits.MethodsPatients undergoing microsurgical clip occlusion for unruptured anterior circulation aneurysms between 2000 and 2019 were included, with ICG-VAG since 2009 and iCT-A/-P (for selected cases) since 2016. Baseline characteristics and treatment-related morbidity/outcome focusing on differences between the three distinct cohorts (cohort-I: pre-ICG-VAG-era, cohort-II: ICG-VAG-era, cohort-III: ICG-VAG&iCT-A/-P-era) were analyzed.Results1391 patients were enrolled (n = 74 were excluded), 779 patients were interventionally treated, 538 patients were surgically clipped by a specialized vascular team (cohort-I n = 167, cohort-II n = 284, cohort-III n = 87). Aneurysm size was larger in cohort-I (8.9 vs. 7.5/6.8 mm; p < 0.01) without differences concerning age (mean:55years), gender distribution (m: f = 1:2.6) and aneurysm location (MCA:61%, ICA:18%, ACA/AcomA:21%). There was a stepwise improvement in the rate of radiologically detected postoperative ischemia (16.2vs.12.0vs.8.0%; p = 0.161), complete aneurysm occlusion (68.3vs.83.6vs.91.0%; p < 0.01) and postoperative new deficits (10.8vs.7.7vs.5.7%; p = 0.335) from cohort-I to -III. After a mean follow-up of 12months, a median modified Rankin scale of 0 was achieved in all cohorts.DiscussionAssociated with periprocedural technical achievements, surgical outcome in elective anterior circulation aneurysm surgery has improved in our service during the past 20 years.

Letter to the Editor Regarding: “Endovascular Treatment and Microsurgical Clipping for the Management of Paraclinoid Intracranial Aneurysms: A Systematic Review and Meta-Analysis

Letter to the Editor Regarding: “Endovascular Treatment and Microsurgical Clipping for the Management of Paraclinoid Intracranial Aneurysms: A Systematic Review and Meta-Analysis

The safety and clinical outcomes of endovascular treatment versus microsurgical clipping of ruptured anterior communicating artery aneurysms: a 2-year follow-up, multicenter, observational study

Background and objectiveCurrent data on the optimal treatment modality for ruptured anterior communicating artery (AComA) aneurysms are limited. We conducted this multicenter retrospective study to evaluate the safety and clinical outcomes of endovascular treatment (EVT) and microsurgical clipping (MC) for the treatment of ruptured AComA patients.MethodsPatients with ruptured AComA aneurysms were screened from the Chinese Multicenter Cerebral Aneurysm Database. Propensity score matching (PSM) was used to adjust for baseline characteristic imbalances between the EVT and MC groups. The safety outcomes included total procedural complications, procedure-related morbidity/death and remedial procedure for complication. The primary clinical outcome was 2-year functional independence measured by the modified Rankin scale (mRS) score.ResultsThe analysis included 893 patients with ruptured AComA aneurysms (EVT: 549; MC: 346). PSM yielded 275 pairs of patients in the EVT and MC cohorts for comparison. Decompressive craniectomy being more prevalent in the MC group (19.3% vs. 1.5%, p &amp;lt; 0.001). Safety data revealed a lower rate of total procedural complications (odds ratio [OR] = 0.62, 95% CI 0.39–0.99; p = 0.044) in the EVT group and similar rates of procedure-related morbidity/death (OR = 0.91, 95% CI 0.48–1.73; p = 0.880) and remedial procedure for complication (OR = 1.35, 95% CI 0.51–3.69, p = 0.657) between the groups. Compared with that of MC patients, EVT patients had a greater likelihood of functional independence (mRS score 0–2) at discharge (OR = 1.68, 95% CI 1.14–2.50; p = 0.008) and at 2 years (OR = 1.89, 95% CI 1.20–3.00; p = 0.005), a lower incidence of 2-year all-cause mortality (OR = 0.54, 95% CI 0.31–0.93; p = 0.023) and a similar rate of retreatment (OR = 1.00, 95% CI 0.23–4.40; p = 1.000).ConclusionClinical outcomes after treatment for ruptured AComA aneurysms appear to be superior to those after treatment with MC, with fewer overall procedure-related complications and no increase in the retreatment rate. Additional studies in other countries are needed to verify these findings.

Letter to the Editor Regarding “Endovascular Treatment and Microsurgical Clipping for the Management of Paraclinoid Intracranial Aneurysms: A Systematic Review and Meta-Analysis”

Letter to the Editor Regarding “Endovascular Treatment and Microsurgical Clipping for the Management of Paraclinoid Intracranial Aneurysms: A Systematic Review and Meta-Analysis”

In Reply to the Letter to the Editor Regarding “Endovascular Treatment and Microsurgical Clipping for the Management of Paraclinoid Intracranial Aneurysms: A Systematic Review and Meta-Analysis”

In Reply to the Letter to the Editor Regarding “Endovascular Treatment and Microsurgical Clipping for the Management of Paraclinoid Intracranial Aneurysms: A Systematic Review and Meta-Analysis”

Contralateral Prechiasmatic Interoptic Approach for Microsurgical Clip Ligation of a Medially Pointing Paraclinoid Internal Carotid Artery Aneurysm

Contralateral Prechiasmatic Interoptic Approach for Microsurgical Clip Ligation of a Medially Pointing Paraclinoid Internal Carotid Artery Aneurysm

Treatment trends and clinical outcomes of endovascular embolization for unruptured intracranial aneurysms in the pediatric population

BackgroundOwing to the relative rarity of unruptured intracranial aneurysms (UIAs) in the pediatric population, evidence regarding treatment modalities and clinical outcomes remains limited.ObjectiveTo characterize the use and clinical outcomes of...

Bypass-Assisted Microsurgical Clipping for an Endovascular Treatment-Resistant Ruptured Internal Carotid-Posterior Communicating Artery Aneurysm, Recurring Two Decades Postinitial Clipping: 2-Dimensional Operative Video.

Salvage treatment of postclipping recurrent aneurysms remains challenging.1,2 The salvage microsurgical clipping is a possible intervention but sometimes difficult because of tissue adhesions around the aneurysm and previously installed clips; therefore, salvage coil embolization may have certain advantages.1-5 However, when coil embolization is not applicable,6 microsurgical clipping is a stand-alone curative treatment, requiring proficient and reliable microsurgical techniques. This article describes a unique case of a 70-year-old female patient complaining of a severe headache with subarachnoid hemorrhage due to a recurrent ruptured left internal carotid-posterior communicating artery aneurysm after microsurgical clipping 23 years ago. An initial attempt at coil embolization proved unsuccessful because of the aneurysm shape. Consequently, the salvage microsurgical clipping was planned. Given the additional time for trapping the internal carotid artery for the old clip removal, a superficial temporal artery-middle cerebral artery bypass was also planned. The operation entailed a superficial temporal artery-middle cerebral artery bypass, a Sylvian fissure dissection, the old clip removal, and aneurysm clipping. Intraoperatively, the complete aneurysm neck clipping was successfully performed without any complication, and patient postoperative course was uneventful. A wide surgical field should be obtained to be able to manipulate the aneurysm and old clip safely under a microscope. It is also important to temporarily trap the main artery to ensure removal of old clips and to prepare for intraprocedural ischemia using bypass after a precise assessment of hemodynamics before surgery. The patient provided informed consent for the procedure and the publication of the case along with its pertinent imaging, and this report was approved by the institutional review board at our hospital.

Microsurgical Clipping of Multiple Intracranial Aneurysms via the Keyhole Approach

BackgroundKeyhole surgery has been widely used to clip various intracranial aneurysms. Here, the feasibility of microsurgical clipping of multiple intracranial aneurysms via the keyhole approach was further investigated. MethodsThe clinical data of 80 patients with multiple intracranial aneurysms treated with keyhole surgery were retrospectively analyzed. The patients included 25 males and 55 females, with an average age of 57.5 years. There were 13 patients with unruptured aneurysms, 67 patients with ruptured aneurysms (small aneurysms accounted for 52.2% of ruptured aneurysms), and a total of 198 aneurysms. A 4 cm incision and a bone hole of approximately 2.5 cm were used, per craniotomy standards. Forty-eight cases were treated via the supraorbital keyhole approach, 45 cases via the pterional keyhole approach, and three cases via the interhemispheric keyhole approach. ResultsA bilateral and unilateral keyhole approach was applied in 18 and 62 cases, respectively. A total of 170 ipsilateral and 7 contralateral aneurysms were clipped. The complete clipping rate was 98.9%. During the follow-up period of 6-12 months after surgery, the Glasgow outcome scale score was 5 points in 74 cases, 4 points in five cases, and 3 points in one case. The prognosis was associated with the preoperative Hunt–Hess classification but not with the number of operative sides, the operation opportunity, or the number of clipped aneurysms. ConclusionEarly keyhole surgical clipping of multiple intracranial aneurysms is an effective treatment. Among ruptured aneurysms, small aneurysms are common and need attention and timely treatment.

Cerebral Aneurysm Characteristics and Surgical Outcomes: An In-Depth Analysis of 346 Cases Operated Using Microsurgical Clipping.

This comprehensive study analyzes 346 surgically treated intracranial aneurysms, emphasizing the importance of understanding risk factors and prevalent characteristics in patients. Intracranial aneurysms, primarily of the saccular or berry type, significantly contribute to nontraumatic subarachnoid hemorrhages and demonstrate a rising incidence due to advances in imaging techniques. The study highlights a gender discrepancy in aneurysm occurrence and a higher prevalence in individuals over 30 years old. The research delves into various aspects, including aneurysm localization, diameter, neck dimensions, and rupture status, with a focus on the anterior communicating artery and middle communicating artery as predominant locations. Significant findings include the prevalence of ruptured aneurysms and the impact of arterial hypertension, atherosclerosis, obesity, and diabetes on aneurysm epidemiology. The study also investigates the occurrence of vasospasm, a significant factor in delayed morbidity and mortality in aneurysmal subarachnoid hemorrhage. The utilization of the Glasgow Outcome Scale and other quantification scales aids in understanding the severity and postoperative outcomes of intracranial aneurysms. Challenges such as the incidence of reopenings and postoperative osteomyelitis are addressed, underlining the need for refined protocols and multidisciplinary approaches in treatment. The study's results contribute to the existing knowledge base on intracranial aneurysms, emphasizing the importance of ongoing research and tailored treatment strategies. The comprehensive nature of this analysis, covering preoperative, intraoperative, and postoperative factors, provides valuable insights into the complex interplay of risk factors and clinical outcomes in patients with intracranial aneurysms.

Training Performance Assessment for Intracranial Aneurysm Clipping Surgery Using a Patient-Specific Mixed-Reality Simulator: A Learning Curve Study.

The value of simulation-based training in medicine and surgery has been widely demonstrated. This study investigates the introduction and use of a new mixed-reality neurosurgical simulator in aneurysm clipping surgery, focusing on the learning curve and performance improvement. Five true-scale craniotomy head models replicating patient-specific neuroanatomy, along with a mixed-reality simulator, a neurosurgical microscope, and a set of microsurgical instruments and clips, were used in the operation theater to simulate aneurysm microsurgery. Six neurosurgical residents participated in five video-recorded simulation sessions over 4 months. Complementary learning modalities were implemented between sessions. Thereafter, three blinded analysts reported on residents' use of the microscope, quality of manipulation, aneurysm occlusion, clipping techniques, and aneurysm rupture. Data were also captured regarding training time and clipping attempts. Over the course of training, clipping time and number of clipping attempts decreased significantly (P = .018, P = .032) and the microscopic skills improved (P = .027). Quality of manipulation and aneurysm occlusion scoring improved initially although the trend was interrupted because the spacing between sessions increased. Significant differences in clipping time and attempts were observed between the most and least challenging patient models (P = .005, P = .0125). The least challenging models presented higher rates of occlusion based on indocyanine green angiography evaluation from the simulator. The intracranial aneurysm clipping learning curve can be improved by implementing a new mixed-reality simulator in dedicated training programs. The simulator and the models enable comprehensive training under the guidance of a mentor.