Category: Vascular

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Natural history and management outcomes of patients with ruptured Spetzler-Martin grade IV and V brain arteriovenous malformations

J Neurosurg 142:667–675, 2025

Study Objective: To explore the natural history and management outcomes of patients with ruptured Spetzler-Martin grade IV and V brain arteriovenous malformations (bAVMs).

• Patient Selection: The study involved 84 patients with ruptured high-grade bAVMs, identified from a database spanning 1990 to 2020.

• Hemorrhagic Risk: Annual hemorrhagic risk was 2.68% for cortical bAVMs and 8.37% for deep-seated bAVMs during natural history.

• Treatment Outcomes: Surgery reduced hemorrhagic risk significantly in cortical bAVMs, while radiosurgery was effective for deep-seated bAVMs. Embolization alone increased hemorrhagic risk.

• Predictors of Success: Surgery and radiosurgery were significant predictors of bAVM obliteration for cortical and deep-seated bAVMs, respectively.

• Management Strategies: Conservative management was compared to surgical interventions, showing similar functional outcomes but differing in obliteration rates.

• Conclusion: Surgery and radiosurgery may be viable options for certain patients, while embolization alone should be avoided

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Idiopathic cerebellar hemorrhage in a patient with isolated developmental venous anomaly: A case report

Surg Neurol Int. 2025;16:82.

A 33-year-old female with severe headaches and vertigo was diagnosed with cerebellar hemorrhage due to an isolated developmental venous anomaly (DVA). Conservative treatment led to full recovery, highlighting the importance of considering DVA in cerebellar hemorrhage etiology and recommending non-surgical management to avoid complications.

• Case Report: Idiopathic cerebellar hemorrhage with isolated developmental venous anomaly in a 33-year-old female.

• Symptoms: Severe headaches, vertigo, left oculomotor nerve palsy, left-sided hemidysmetria.

• Initial Misdiagnosis: Meniere’s disease.

• Imaging Findings: Acute hemorrhage in cerebellar vermis, isolated DVA with “caput medusae” sign.

• Management: Conservative treatment with steroids and analgesics, full recovery.

• DVA Characteristics: Benign anatomical variation, low-flow malformation, rarely causes hemorrhage.

• Hemorrhage Risk Factors: Coexisting cavernous malformation or arteriovenous malformation increase risk.

• Study Findings: Hemorrhage risk 0.22–0.68%/year, higher in infratentorial DVAs.

• Surgical Intervention: Reserved for life-threatening mass effects or raised intracranial pressure.

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Conservative management of brain arteriovenous malformations: results of the prospective observation registry of a pragmatic trial

J Neurosurg 142:637–646, 2025

• Study Overview: TOBAS study on conservative management of brain AVMs.

• Objective: Monitor outcomes of patients with brain AVMs managed conservatively.

• Primary Outcome: Death or dependency (mRS score > 2) at 10 years.

• Patient Recruitment: 1010 patients recruited, 498 in observation registry.

• Follow-up Results: Low incidence of death or disability, 1.7% per year.

• Risk Factors: History of rupture, infratentorial location, age ≥ 55 years increase poor outcomes.

• SAEs Incidence: 3.6 per 100 patient-years, higher in ruptured AVMs.

• Methodology: Kaplan-Meier curves, Cox log-rank tests used for analysis.

• Study Design: Multicenter, includes randomized trials and prospective registries.

• Data Collection: Simple electronic forms, Good Clinical Practice compliance.

• Patient Characteristics: Majority with unruptured, low-grade AVMs.

• Statistical Analysis: Cox models and hazard ratios used.

• Conclusions: Observed patients had low rates of adverse neurological events

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From conservative to interventional management in unruptured intracranial aneurysms

J Neurosurg 142:619–625, 2025

• Study Focus: Management of unruptured intracranial aneurysms (UIAs) from conservative to interventional.

• Objective: Identify patterns and predictors for revising UIA management strategy.

• Methodology: Retrospective review of cases diagnosed between 2006-2022 with conservative management.

• Results: 10 of 144 cases shifted to interventional treatment due to aneurysm growth.

• UIA Growth: Most frequent reason for changing treatment strategy.

• Size Threshold: UIAs > 3 mm at diagnosis more likely to require intervention.

• Conservative Management: Regular radiographic follow-ups recommended, especially for UIAs > 3 mm.

• Guidelines: ESO and American Heart Association guidelines emphasize monitoring UIA growth.

• Statistical Analysis: Cox regression and Kaplan-Meier curves used for data analysis.

• Risk Factors: No significant effect of potential risk factors on treatment change.

• Imaging: DSA as confirmative modality for revising conservative management.

• Study Limitations: Low statistical power due to limited cases of treatment change.

• Conclusion: Regular monitoring crucial for conservatively managed UIAs, especially > 3 mm.

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Aneurysm Wall Enhancement Can Predict Rupture Point in Intracranial Aneurysms With Multiple Blebs

Neurosurgery 96:593–599, 2025

• Aneurysm Wall Enhancement (AWE) can predict rupture points in intracranial aneurysms with multiple blebs.

• Vessel Wall MRI (VW-MRI) is used to visualize ruptured aneurysms, showing characteristic AWE.

• Higher AWE is associated with ruptured blebs, while lower wall shear stress (WSS) is observed in ruptured versus unruptured blebs.

• CRstalk (contrast ratio of the aneurysm wall against the stalk) is a significant predictor of rupture status, with higher values indicating ruptured blebs.

• AWE is independent of WSS in predicting rupture status and can guide treatment strategies.

• Study limitations include its retrospective nature and small sample size; future studies with high-resolution MRI are suggested.

• Clinical value: AWE helps determine which aneurysm to treat first, especially in cases with multiple aneurysms, improving surgical safety.

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Association of Global Ultraviolet Radiation With the Incidence of Aneurysmal Subarachnoid Hemorrhage

Neurosurgery 96:396–401, 2025

• Study Focus: The research investigates the association between global ultraviolet (UV) radiation and the incidence of aneurysmal subarachnoid hemorrhage (SAH).

• Inverse Correlation: A significant inverse correlation between UV radiation and SAH incidence was found, suggesting higher UV exposure is linked to lower SAH rates.

• Methodology: Data from 32 countries were analyzed using UV indices from the Tropospheric Emission Monitoring Internet Service, with statistical analyses performed using R and Excel.

• Geographic Variations: The study found significant regional differences, with higher UV indices in Europe associated with lower SAH incidences, but this was not significant in non-European countries.

• Biological Implications: UV radiation may reduce inflammation, potentially decreasing the risk of aneurysm rupture, and may also boost vitamin D synthesis, which is linked to improved immune response.

• Limitations: The study faced limitations, including lack of data from some countries and inability to assess seasonal influences due to variability in study periods.

• Conclusion: The findings suggest that environmental factors like UV exposure may influence SAH incidence, warranting further investigation into potential therapeutic implications.

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A taxonomy for cerebellar cavernous malformations: subtypes of cerebellar lesions

J Neurosurg 142:380–393, 2025

• A novel taxonomy for cerebellar cavernous malformations (CMs) is proposed, introducing six distinct subtypes based on anatomical location.

• The study was conducted over a 25-year period and involved 143 cerebellar CMs treated microsurgically.

• The subtypes include suboccipital, tentorial, petrosal, vermian, tonsillar, and deep nuclear lesions.

• Favorable neurological outcomes were achieved in 91% of cases, with a mean follow-up of 37.4 months.

• Surgical approaches were guided by the CM subtypes, aiming to minimize tissue transgression and preserve function.

• Complete resection was achieved in 94% of cases, with no significant differences in outcomes between subtypes.

• The taxonomy aids in selecting craniotomy and approach to enhance patient safety and optimize outcomes.

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Intracranial Arteriovenous Malformations During Pregnancy and Puerperium

Neurosurgery 96:346–355, 2025

Study Overview

• Focus: Brain AVM during pregnancy and puerperium.

• Method: Retrospective cohort study in Finland from 1987 to 2016.

• Data Sources: National Hospital Discharge Register, Medical Birth Register, and AVM registry.

Key Findings

• AVM Rupture: Occurred mostly in the second and third trimesters.

• Previous Pregnancies: Most women with AVM rupture had previous pregnancies.

• Treatment Timing: 35.7% received treatment during pregnancy or puerperium.

• Outcomes: No significant difference between treated and conservatively managed mothers.

Maternal and Fetal Outcomes

• Maternal Mortality: Last AVM-related fatality during pregnancy was in 1988.

• Newborn Health: Most had favorable outcomes, with Apgar scores similar between groups.

• Delivery: Average gestation at delivery was 38 weeks.

Clinical Implications

• Management: Multidisciplinary approach recommended for AVM treatment during pregnancy.

• Research Needs: More studies needed on AVM rupture risk related to delivery method.

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Multistaged Stereotactic Radiosurgery for Complex Large Lobar Arteriovenous Malformations

Neurosurgery 96:223–232, 2025

Although stereotactic radiosurgery (SRS) has well defined outcomes in the management of smaller-volume arteriovenous malformations (AVM), this report evaluates the outcomes when SRS is used for large-volume (≥10 cc) lobar AVMs.

METHODS: Between 1990 and 2022, a cohort of 1325 patients underwent Leksell Gamma Knife SRS for brain AVMs. Among these, 40 patients (25 women; median age: 37 years) with large lobar AVMs underwent volume-staged SRS followed by additional SRS procedures if needed (2-5 procedures). The patients presented with diverse AVM locations and Spetzler-Martin Grades. Before SRS, 16 patients underwent a total of 43 embolization procedures.

RESULTS: Over a median follow-up of 73 months, 20 patients achieved AVM obliteration. The 3, 5, and 10-year obliteration rates were 9.3%, 15.3%, and 53.3%, respectively. During the latency interval between the first SRS procedure and the last follow-up, 11 patients had intracerebral hemorrhages (ICH) and 6 developed new neurological deficits unrelated to ICH. The postoperative hemorrhage risk after the first SRS was 13.8% at 3 years, 16.6% at 5 years, and 36.2% at 10 years. No hemorrhagic event was documented after confirmed obliteration. Compared with the modified Rankin Scale (mRS) scores before SRS, the mRS improved or remained stable in 28 patients. Nine patients died during the observation interval. Five were related to ICH.

CONCLUSION: These outcomes underscore both the potential effectiveness and the limitations of multistage SRS procedures for complex high-risk large volume AVMs in critical brain lobar locations. Most patients retained either stable or improved long-term mRS scores. During the latency interval from the first SRS until obliteration, achieved after two or more procedures, the risk of hemorrhage and treatment-related complications persists.

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Anterior choroidal artery aneurysms: a systematic review and meta-analysis of outcomes and ischemic complications following surgical and endovascular treatment

J Neurosurg 142:127–137, 2025

Anterior choroidal artery (AChA) aneurysms account for 2%–5% of all intracranial aneurysms. Treatment considerations include microsurgical clipping, flow diversion, or coiling with or without adjunctive devices. AChA aneurysms pose challenges in treatment due to the origination of the aneurysm from the origin or proximal segment of the AChA. The AChA is particularly susceptible to vasospasm and occlusion during treatment with devastating neurological deficits, including hemiparesis, hemianesthesia, lethargy, neglect, and hemianopia. In this study, the authors performed a meta-analysis to quantify the outcomes and complication rates across treatment modalities for AChA aneurysms and to identify risk factors reported in the literature.

METHODS The authors performed a systematic review of AChA aneurysms treated with surgical clipping, endovascular coiling, or flow diversion and reported in the PubMed, Embase, Scopus, and Cochrane search databases. Single-arm meta-analyses of the selected outcomes were performed in RStudio.

RESULTS Literature review yielded 25 studies that met the inclusion criteria. In total, 1627 patients were included in the analysis, with 554 males, 1009 females, and 64 unspecified. The rate of any complication in the full cohort was 11.6%, with a rate of ischemic complications of 5.5% and a favorable recovery rate of 90.3% of all patients treated. In total, 1064 patients underwent surgical clipping, 443 were treated with coiling, and 120 patients with flow diversion. In clipped patients, the rate of total surgical complications was 17.6%, with an ischemic complication rate of 9.4%. The rate of good functional recovery, defined on the basis of a Glasgow Outcome Scale score of 4–5 or modified Rankin Scale score of 0–2, was 88.0%, and complete obliteration was achieved in 84.5% of surgically clipped aneurysms. The complication rate in coiled patients was 10.3%, with an ischemic complication rate of 3.0%. Good functional recovery was achieved in 88.6% of coiled patients and complete aneurysm obliteration in 74.1%. Flow diversion resulted in a complication rate of 1.3%, with 0.7% rate of ischemic complications. Good functional recovery was achieved in 98.4% of patients and complete aneurysm obliteration in 79.0% in the flow diversion group. Aneurysm morphological features that impacted the complication rate were also identified to augment quantitative data and to help guide treatment selection for AChA aneurysms.

CONCLUSIONS Flow diversion showed significantly lower total and ischemic complications and improved outcomes compared to clipping and coiling. There may be differences in outcomes between treatment types, especially when considering the varied patient presentations that guide treatment selection.

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Nighttime Treatment of Ruptured Intracranial Aneurysms Are Associated With Poor Outcomes

Neurosurgery 96:78–86, 2025

Rebleeding of ruptured intracranial aneurysms (RIA) is associated with poor outcomes. Although immediate treatment of RIAs is preferred, optimal treatment timing is multifactorial and may be a complicating factor for achieving the best outcomes. The objective of this study was to compare outcomes for patients with RIAs as a function of treatment time of day. To the best of our knowledge, this is the first study that examines how treatment time of day influences treatment outcomes.

METHODS: This retrospective single-center study included all patients who were treated, either surgically or endovascularly, for RIAs within 24 hours after admission. Exclusion criteria were blister, mycotic or giant aneurysms, or incomplete records. The modified Rankin Scale was used to evaluate treatment outcomes using multivariate analysis. Nighttime treatment was defined when greater than 50% of the procedure was performed between 10 PM and 7 AM, with other times classified as daytime treatment. Off-hours treatment was defined when more than 50% of the procedure was performed between 7 PM and 7 AM, with other times classified as on-hours.

RESULTS: This study included 493 patients, with 84.2% (415) treated during the daytime, 15.8% (78) during the nighttime, 67.5% (333) during on-hours, and 32.5% (160) during off-hours. These groups did not differ according to age, sex, World Federation of Neurosurgical Societies and Fisher scales, aneurysm size, location, and surgical or endovascular treatment. Outcomes were favorable (modified Rankin Scale 0-2) for 72.0% (299) of patients treated during the daytime and 60.0% (46) of patients treated during the nighttime. Aneurysm treatment during the nighttime (OR: 0.50 [95% CI: 0.28-0.91], P = .023) but not during off-hours (OR: 0.76 [0.50-1.14], P = .18) was independently associated with unfavorable outcomes.

CONCLUSION: Nighttime treatment was associated with poorer outcomes. Further studies are needed to evaluate outcomes if treatment is postponed to daytime hours.

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Comparing surgical clipping with endovascular treatment for unruptured middle cerebral artery aneurysms: a systematic review and updated meta-analysis

J Neurosurg 142:116–126, 2025

Unruptured middle cerebral artery aneurysm (uMCAA) has traditionally been treated with open surgical clipping (SC). Endovascular treatments (EVTs) were designed to reduce surgical risks in these cases. Nevertheless, despite its potential benefits, many surgeons favor SC for uMCAA. This updated meta-analysis aimed to compare the safety, efficacy, and clinical outcomes of SC and EVT for uMCAA.

METHODS The authors searched the Medline, Embase, and Cochrane Library databases according to the Cochrane and PRISMA guidelines. Eligible studies included those with ≥ 4 patients with uMCAA reporting comparative data of SC and EVT. The endpoints were the complete occlusion rate (Raymond class I and II), good clinical outcomes (modified Rankin Scale score ≤ 2 or Glasgow Outcome Scale score ≥ 4), procedure-related complications (further divided into major and minor), and mortality. The authors pooled OR with 95% CI values with a random-effects model. I 2 statistics were used to assess heterogeneity, and sensitivity analysis was conducted to address high heterogeneity. Publication bias was assessed with funnel plot analysis and the Egger’s test.

RESULTS The analysis included data from 10 studies. Regarding the complete occlusion assessment, the comparative analysis revealed OR 0.17 (95% CI 0.08–0.40, p < 0.01), favoring SC. In terms of achieving good clinical outcomes, OR 0.44 (95% CI 0.20–0.97, p < 0.05) was determined, favoring SC. No differences regarding total procedure-related complications, major complications, or mortality were identified. However, a higher likelihood of minor complications was identified for EVT, with OR 4.68 (95% CI 2.01–10.92, p < 0.01).

CONCLUSIONS This systematic review and meta-analysis identified a lower likelihood of complete occlusion at last follow-up and lower likelihood of good clinical outcomes in patients treated with EVT when compared with SC. Furthermore, a higher likelihood of minor complications was identified in patients who underwent EVT when compared with SC. The findings reinforce that, based on the currently available data, SC should be considered the primary approach for treating uMCAA. However, EVT is an evolving approach, and this study’s findings represent a synthesis of observational studies. Randomized trials are warranted to elucidate which approach should be the mainstay for uMCAA and to identify the nuances that determine whether SC or EVT is more or less indicated for addressing uMCAA with consideration of the individuality of each patient and aneurysm.

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Optimal Timing of Microsurgical Treatment for Ruptured Arteriovenous Malformations: A Systematic Review and Meta-Analysis

Neurosurgery 96:18–28, 2025

The timing of microsurgical treatment (MST) for ruptured brain arteriovenous malformations (bAVM) is a contentious issue in the literature. This study aimed to investigate the impact of MST timing on outcomes in patients with ruptured bAVMs, considering MST with and without preoperative endovascular treatment (EVT).

METHOD: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines, a comprehensive search was conducted across multiple databases, yielding 15 studies meeting the inclusion criteria. The timing was defined as the duration from the rupture of bAVM to the MST. The patients were divided into 4 different groups based on MST timing: <48 hours, <1 week, <2 weeks, and <1 month. The primary outcome was favorable outcome defined as a modified Rankin Scale score of 0 to 2 or a Glasgow Outcome Scale score of 4 to 5 in the last clinical follow-up. Secondary outcomes included periprocedural mortality and complete excision.

RESULTS: MST time >48 hours were associated with a significantly higher favorable outcome rate (odds ratio: 9.71, 95% Cl: 3.09-30.57, P < .01) and a lower mortality rate (OR: 0.15, 95% Cl: 0.02-0.88, P = .04) compared with MST timing ≤48 hours. After exclusion of patients who underwent MST with preoperative EVT, MST time >48 hours had a significantly higher rate of favorable outcome (OR: 9.39, 95% CI: 2.53-34.89, P < .01).

CONCLUSION: This meta-analysis suggests that delayed surgical intervention beyond 48 hours may be associated with improved favorable outcomes in patients who underwent MST with and without preoperative EVT for ruptured bAVMs.

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The human craniospinal venous system and its influence on postural intracranial pressure: a review

J Neurosurg 141:1484–1493, 2024

The cerebral and spinal venous systems have similar functions but unique anatomical and physiological properties. CSF occupies space in the cranial and spinal vaults, is continuously produced, and has many roles, including maintaining a favorable environment for CNS structures. The influence of the cerebrospinal venous system on CSF dynamics has been theorized since the 1940s. Newer studies suggest venous outflow pattern alterations in response to changes in body position. However, the relationship of postural cerebrospinal venous outflow shifts with and their influence on CSF homeostasis is not well understood.

METHODS The authors searched the published literature related to the anatomy and function of vertebral venous plexus (VVP), CSF, and positional cerebral venous flow characteristics. A comprehensive collection of literature was compiled and reviewed, and the relationship between cerebrospinal and venous system changes and alterations in body positions, with an emphasis on the craniocervical system, is discussed.

RESULTS The VVP is a network of valveless veins extending from the sacrum to the cranium that are interconnected with the cranial dural sinuses. The internal VVP occupies space within the extradural spinal canal and functions to return spinal venous blood to the heart, but it has additional properties, including the capability of bidirectional venous flow, an intraspinal dilatory capacity, and a role in cerebral venous outflow. When one rises to the upright position, CSF shifts toward the spinal canal and force vectors change, leading to reduced intracranial CSF pressure; simultaneously, cerebral venous outflow shifts from the jugular vein to the VVP outflow pathway. The venous outflow shift mechanism and its purpose are poorly understood. The authors review the known physiology of the system, identify gaps in knowledge to direct future research, and propose an interpretation of these data, concluding that position-dependent CSF and cerebrospinal venous shifts are part of a complementary positional craniospinal pressure regulation system that must be kept in balance for optimal CNS function.

CONCLUSIONS Current knowledge of the cerebrospinal venous anatomy, dynamic flow characteristics in response to gravity, and the venous system’s influence on CSF suggests that the VVP plays a role in influencing CSF pressure, and the authors hypothesize that it plays a role in supporting intracranial pressure in the upright body posture. Further research is needed to better characterize the functional relationship of the VVP to CSF dynamics as well as identify potentially related disease states.

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Analysis of the Efficacy of Neuroendoscopic Hematoma Removal Combined With Ventricular Lavage in Severe Intraventricular Hemorrhage—A Prospective Randomized Controlled Study

Neurosurgery 95:1297–1306, 2024

The current widely utilized clinical approach for severe intraventricular hemorrhage involves ventriculostomy with supportive drainage. The aim of our study was to evaluate the overall efficacy of neuroendoscopic hematoma removal combined with ventricular lavage as a treatment approach for severe intraventricular hemorrhage.

METHODS: A prospective randomized controlled study was conducted, selecting a total of 98 patients with severe intraventricular hemorrhage at our hospital from February 2021 to November 2022. The patients were randomly distributed into 2 groups using a randomized number table method: the neuroendoscopic group (undergoing neuroendoscopic hematoma removal combined with ventricular lavage) and the control group (undergoing intraventricular trepanation and drainage), with 49 patients in each group.

RESULTS: The neuroendoscopic group had significantly higher intraoperative blood loss than that of the control group (P = .037), while the drainage tube indwelling time and hospital stay in the neuroendoscopic group were significantly shorter (P < .001). At 6 hours (P = .021), 1 day (P = .002), 3 days (P < .001) and 7 days (P = .007) following surgery, the neuroendoscopic group exhibited evidently higher hematoma clearance rates compared with the control group. At 1 day and 3 days after surgery, the cerebrospinal fluid drainage volume in the neuroendoscopic group was significantly higher than that in the control group (P < .001), whereas at 7 days after surgery, it was significantly lower in the neuroendoscopic group compared with the control group (P < .001). Moreover, significantly lower incidence of intracranial infection (P = .045) and increased intracranial pressure (P = .008) was observed in the neuroendoscopic group compared with the control group.

CONCLUSION: Neuroendoscopic hematoma removal combined with ventricle lavage emerged as an effective treatment strategy for severe intraventricular hemorrhage, yielding significant therapeutic benefits. Therefore, this approach holds promise for broader clinical application and promotion.

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Surgical interruption of high‑flow dural arteriovenous fistulas at the foramen magnum region

Acta Neurochirurgica (2024) 166:467

Dural arteriovenous fistulas (dAVFs) in the foramen magnum region (FMR) are rare entity of dAVFs. There is no established treatment for FMR-dAVFs owing to their rarity and anatomical complexity. Herein, we report cases of highflow dAVFs located at the posteromedial part of the FMR that were successfully treated by surgical interruption.

Methods We demonstrated the surgical procedures for the interruption of high-flow FMR-dAVF with representative images and videos. In both cases, endovascular transarterial embolization was performed prior to surgical interruption.

Conclusion As this type of FMR-dAVF has high-risk clinical features, curative surgical treatment is highly desirable.

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

Operative Neurosurgery 27:581–596, 2024

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.

METHODS: 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.

RESULTS: 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.

CONCLUSION: 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.

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Arteriovenous malformations in the cerebellopontine angle: assessment of the “backdoor resection” technique and microsurgical results in 38 patients

J Neurosurg 141:1198–1211, 2024

Posterior fossa arteriovenous malformations (AVMs) represent 7% to 15% of all intracranial AVMs and are associated with an increased risk of hemorrhage, morbidity, and mortality compared with supratentorial AVMs, thus prompting urgent and definitive treatment. Cerebellopontine angle (CPA) AVMs are a unique group of posterior fossa AVMs incorporating characteristics of brainstem and cerebellar lesions, which are particularly amenable to microsurgical resection. This study reports the clinical, radiological, operative, and outcome features of patients with CPA AVMs in a large cohort.

METHODS The authors conducted a single-surgeon, 2-institution retrospective cohort study of all consecutive patients with CPA AVMs treated with microsurgical resection during a 25-year period.

RESULTS CPA AVMs represented 22% (38 of 176) of all infratentorial AVMs resected by the senior author. Overall, 38 patients (22 [58%] male and 16 [42%] female) met the study inclusion criteria and were analyzed. Most patients presented with hemorrhage (n = 29, 76%). The median age at surgery was 56 (range 6–82) years. Subtypes included 22 (58%) petrosal cerebellar AVMs, 11 (29%) lateral pontine AVMs, and 5 (13%) AVMs involving both the brainstem and cerebellum. Most AVM niduses were small (< 3 cm; n = 35, 92%) and compact (n = 31, 82%). Fourteen (37%) patients harbored flow-related aneurysms. Twenty (53%) patients underwent preoperative embolization. Complete angiographic obliteration was achieved with microsurgery in 35 (92%) patients. Five (13%) patients with poor neurological conditions at presentation died before hospital discharge. Of the 7 (18%) patients with new postoperative neurological deficits, 5 had transient deficits. The median (interquartile range) follow-up was 1.7 (0.5–3.2) years; 32 (84%) patients were alive at last follow-up, and 30 (79%) had achieved a favorable neurological outcome (modified Rankin Scale [mRS] score 0–2). The only independent predictor of unfavorable postoperative outcome (mRS score 3–6) was the preoperative mRS score (p = 0.002).

CONCLUSIONS CPA AVMs are unique posterior fossa lesions, including petrosal cerebellar and lateral pontine AVMs. The “backdoor resection” technique provides a safe and efficient strategy with high obliteration rates and a low risk of treatment-related morbidity. Microsurgical resection should be considered the frontline treatment for most CPA AVMs, except for those with a significant diffuse brainstem component.

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Microsurgical management of recurrent intracranial aneurysm after endovascular treatment: a series of 60 consecutive patients

J Neurosurg 141:1235–1243, 2024

The aim of this study was to evaluate the morbidity associated with microsurgical treatment in patients with a recurrent aneurysm to improve their surgical management.

METHODS From 2012 to 2022, among the 3128 patients with ruptured or unruptured intracranial aneurysms managed at the authors’ institution, 954 patients were treated by a microsurgical procedure. Of these 3128 patients, 60 consecutive patients (6.3%) who had a recurrent microsurgically treated aneurysm after previous endovascular treatment were included in this study. Additional microsurgical treatment was considered in case of progressive remnant growth or significant aneurysm recurrence. Intraoperative and postoperative complications were noted. Early (< 7 days) and long-term clinical and radiological monitoring were performed. Good functional outcome was considered as a modified Rankin Scale score < 3.

RESULTS The mean age at initial treatment was 45 years (range 26–65 years). The mean delay between the first treatment and microsurgical treatment of the recurrence was 64 months (range 2 days–296 months). The mean size of the fundus recurrence was 5 mm, and the mean size of the neck recurrence was 4.6 mm. Five patients (8.3%) presented with subarachnoid hemorrhage associated with rupture of the recurrent aneurysm. Three patients died (6%) of aneurysm rupture and/or intensive care complications. The total morbidity rate associated with the microsurgical procedure was 14.5% (8/55) in patients with unruptured recurrent aneurysms. Among these patients, postoperative definitive complications (ischemic lesions) directly related to the microsurgical procedure were present in 3 patients (5.5%). Intraoperative rupture was recorded in these 3 patients. In the 54 surviving patients with unruptured recurrent aneurysms, good functional outcome was noted in 49 (91%). Poor functional outcome was significantly associated with intraoperative rupture.

CONCLUSIONS Microsurgery remains an effective therapeutic option for recurrent intracranial aneurysms. However, in the authors’ experience, postoperative morbidity is higher than in patients with nonrecurrent aneurysms. Therefore, a pretherapeutic multidisciplinary evaluation is mandatory to reduce the potential morbidity associated with the retreatment as much as possible. When endovascular occlusion of the aneurysm requires both stenting and coiling, alternative microsurgical treatment should be carefully evaluated, as microsurgical clipping will become much more challenging in cases of aneurysm recurrence.

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Contemporary cohort of cerebral cavernous malformations: natural history and utility of follow-up MRI

J Neurosurg 141:1159–1167, 2024

This study reports the natural history of cerebral cavernous malformations (CCMs) in a contemporary cohort with prospectively collected data from multiple sources, access to follow-up imaging, integrated electronic medical records, and detailed imaging review by study investigators. The authors aimed to define the first prospective symptomatic hemorrhage (SH) and severe SH rates, determine the risk of a second prospective SH, and identify risk factors for SH.

METHODS From a prospectively maintained database of adult patients with radiologically defined CCM, those with radiation-induced CCM, those who underwent surgery within 3 months postdiagnosis, and those with < 1 year of followup were excluded. The patients’ medical history and radiological features of the CCM were recorded at the time of diagnosis. Follow-up annual written surveys were completed for 5 years after the initial diagnosis and then semiannually thereafter in addition to medical record and follow-up imaging review. Outcomes of interest included SH and severe SH.

RESULTS Of 315 patients, 58.7% were female and 19.7% had familial CCMs. At diagnosis, 37.1% of patients had ruptured CCMs and 28.9% of the CCMs were located in the brainstem. The 5-year cumulative rates of prospective SH and severe SH in those with ruptured CCMs at diagnosis were 41.2% and 12.8%, respectively, compared with 6.1% and 2.5% in patients with unruptured CCMs at diagnosis (p < 0.0001). Risk factors for prospective SH included a ruptured CCM at diagnosis and persistent or new hyperintensity on T1-weighted MRI performed > 3 months after baseline MRI. For those with a ruptured CCM at diagnosis, the risk of developing a second prospective SH was similar to that of developing a first SH.

CONCLUSIONS In a contemporary cohort of adult patients with CCM, the authors report 5-year SH and severe SH rates, rates of second prospective hemorrhage, and predictors of SH. Persistent or new hyperintensity on T1-weighted MRI may be a useful marker of disease activity.

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