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Background: Arteriovenous malformations (AVMs) are uncommon cerebral lesions that can cause significant neurological complications. Surgical resection is the gold standard for treatment, but endovascular embolization and stereotactic radiosurgery (SRS) are viable alternatives., Objective: To compare the outcomes of endovascular embolization versus SRS in the treatment of AVMs with Spetzler-Martin grades I-III., Methods: This study combined retrospective data from 10 academic institutions in North America and Europe. Patients aged 1 to 90 years who underwent endovascular embolization or SRS for AVMs with Spetzler-Martin grades I-III between January 2010 and December 2023 were included., Results: The study included 244 patients, including 84 who had endovascular embolization and 160 who had SRS. Before propensity score matching (PSM), complete obliteration at the last follow-up was achieved in 74.5% of the SRS group compared with 57.8% of the embolization group (OR=0.47; 95% CI 0.26 to 0.48; P=0.01). After propensity score matching, SRS still achieved significantly higher occlusion rates at last follow-up (78.9% vs 55.3%; OR=0.32; 95% CI 0.12 to 0.90; P=0.03).Hemorrhagic complications were higher in the embolization group than in the SRS group, although this difference did not reach statistical significance after PSM (13.2% vs 2.6%; OR=5.6; 95% CI 0.62 to 50.47; P=0.12). Similarly, re-treatment rate was higher in the embolization group (10.5% vs 5.3%; OR=2.11; 95% CI 0.36 to 12.31; P=0.40) compared with the SRS group., Conclusion: Our findings indicate that SRS has a significantly higher obliteration rate at last follow-up compared with endovascular embolization. Also, SRS has a higher tendency for fewer hemorrhagic complications and lower re-treatment rate. Further prospective studies are needed., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Microneurosurgical techniques remain crucial for managing neurosurgical diseases, especially in low- and middle-income countries (LMICs) where other advanced treatment modalities are not available. The global distribution of these techniques is uneven due to disparities in infrastructure, equipment, and training. Medical professionals from LMICs face barriers in reaching training centers in high-income countries, as well as in accessing microsurgical techniques. To address these disparities in microsurgery training, we offer free and accessible microsurgery training model by combining the donations of microsurgery kits with a comprehensive support system that includes live-streamed, offline, and in-person assistance within LMICs., Competing Interests: Disclosure The authors have nothing to disclose., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background and Objectives: Access to the jugular fossa pathologies (JFPs) via the transmastoid infralabyrinthine approach (TI-A) using the nonrerouting technique (removing the bone anterior and posterior to the facial nerve while leaving the nerve protected within the fallopian canal) or with the short-rerouting technique (rerouting the mastoid segment of the facial nerve anteriorly) has been described in previous studies. The objective of this study is to compare the access to Fisch class C lesions (JFPs extending or destroying the infralabyrinthine and apical compartment of the temporal bone with or without involving the carotid canal) between the nonrerouting and the short-rerouting techniques. Also, some tailored steps to the nonrerouting technique (NR-T) were outlined to enhance access to the jugular fossa (JF) as an alternative to the short-rerouting technique., Methods: Neuronavigated TI-A was performed using the nonrerouting, tailored nonrerouting, and short-rerouting techniques on both sides of 10 human head specimens. Exposed area, horizontal distance, surgical freedom, and horizontal angle were calculated using vector coordinates for nonrerouting and short-rerouting techniques., Results: The short-rerouting technique had significantly higher values than the NR-T ( P < .01) for the exposed area (169.1 ± SD 11.5 mm 2 vs 151.0 ± SD 12.4 mm 2 ), horizontal distance (15.9 ± SD 0.6 mm vs 10.6 ± SD 0.5 mm 2 ), surgical freedom (19 650.2 ± SD 722.5 mm 2 vs 17 233.8 ± SD 631.7 mm 2 ), and horizontal angle (75.2 ± SD 5.1° vs 61.7 ± SD 4.6°). However, adding some tailored steps to the NR-T permitted comparable access to the JF., Conclusion: Neuronavigated TI-A with the short-rerouting technique permits wider access to the JF compared with the NR-T. However, the tailored NR-T provides comparable access to the JF and may be a better option for class C1 and selected class C2 and C3 JFPs., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Rapid identification of the type and origin of a stroke is crucial for prompt and appropriate treatment, which can significantly influences patient outcomes. We report a multidisciplinary management case involving a 76-year-old man who presented with left-sided weakness and mild dysarthria. Imaging revealed a completely occluded right internal carotid artery. Despite multiple endovascular recanalization attempts, adequate flow could not be achieved, leading to the decision to perform an open thrombo-endarterectomy. The patient underwent carotid endarterectomy with microsurgical techniques under general anesthesia. The atheroma plaque and central thrombus were removed, which reestablished flow. Continuous intraoperative neuromonitoring was utilized to ensure patient safety. The patient woke up without new deficits and was discharged for rehabilitation. Follow-up imaging confirmed arterial patency, and the patient eventually made an excellent recovery, including being independent over one and a half years. Emergent recanalization with carotid endarterectomy following a failed endovascular recanalization is both safe and feasible, emphasizing the need for collaboration between different treatment providers to ensure optimal patient outcomes. Our report highlights the importance of a multidisciplinary approach and the advantages of a hybrid operating room in the treatment of acute complete carotid artery occlusion.

Objective: As presented in Part 1 of this series, thalamic gliomas (TGs) are deep-seated, difficult-to-access tumors surrounded by vital neurovascular structures. Given their high operative morbidity, TGs have historically been considered inoperable lesions. Although maximal safe resection (MSR) has become the treatment standard for lobar and even deep-seated mediobasal temporal and insular gliomas, the eloquent location of TGs has precluded this management strategy, with biopsy and adjuvant treatment being the mainstay. The authors hypothesized that MSR can be achieved with low morbidity and mortality for TGs, thus resulting in improved outcomes., Methods: A retrospective single-center study was performed on all TG patients from 2006 to 2020. Clinical, imaging, and pathology reports were obtained. Univariate and multivariate analyses were performed to determine prognostic variables. Case examples illustrate various approaches and the rationale for staging resections of more complex TGs., Results: A total of 42 patients (26 males, 16 females), among them 12 pediatric (29%) cases, were included. Their mean age was 36.0 ± 21.4 (median 30, range 3-73) years. The median maximal tumor diameter was 45 (range 19-70) mm. Eighteen patients (43%) had a prior stereotactic needle tumor biopsy, with the ultimate diagnosis changed for 7 patients (39%) following microsurgical resection. The most common surgical approaches were transtemporal (29%), anterior interhemispheric transcallosal (29%), and superior parietal lobule (25%). Overall, the combined subtotal and gross-total resection rate was 95% (n = 40). Low-grade gliomas (LGGs; grades I and II) comprised one-third of the group, whereas half of the patients had glioblastoma multiforme. There were no operative mortalities. Although temporary postoperative motor deficits were observed in 12 patients (28.6%), all improved during the early postoperative period except 1 (2.4%), who had mild residual hemiparesis. Two patients required CSF diversion for hydrocephalus. The 2-year overall survival rate was 90% for LGG patients and 15% for high-grade glioma (HGG) patients. Multivariate analysis revealed that histological grade, age, and extent of resection were independent prognostic factors associated with survival., Conclusions: Management of TGs is challenging, with resection avoided by many, if not most, neurosurgeons, especially for HGGs. The results reported here demonstrate improved outcomes with resection, particularly in younger LGG patients. The authors therefore advocate for MSR for a select cohort of TG patients using carefully planned surgical approaches, contemporary intraoperative adjuncts, and meticulous microsurgical techniques.

Objective: The selection of appropriate microsurgical approaches to treat thalamic pathologies is currently largely subjective. The objective of this study was to provide a structured cartography map for surgical navigation to treat gliomas involving different surfaces of the thalamus., Methods: Fifteen formalin-fixed, silicone-injected cadavers (30 sides) were dissected, and 10 adult brain specimens (20 sides) were used to illustrate thalamic microsurgical anatomy using the Klingler fiber dissection technique. Exposures and trajectories for the six most common microsurgical approaches were depicted using MR data from healthy subjects converted into surface-rendered 3D virtual brain models. Additionally, thalamic surfaces exposed with all six approaches were color mapped on the virtual 3D model and compared side-by-side in 360° views with previously reported microsurgical approaches. These 3D models were then used in conjunction with topographic data to guide cadaveric dissection steps., Results: There are two general surgical routes to thalamic lesions: the subarachnoid transcisternal and transcortical routes. The transcisternal route consists of the following three approaches: 1) anterior interhemispheric transcallosal approach, which exposes the anterior and superior thalamus; 2) posterior interhemispheric transcallosal approach, which exposes the posterosuperior thalamus; and 3) supracerebellar infratentorial approach, which exposes the posteromedial cisternal thalamus and can be extended laterally to approach the posterolateral thalamus by cutting the tentorium. The three transcortical approaches are the 1) superior parietal lobule approach, which exposes the posterosuperior thalamus and is particularly advantageous in the setting of hydrocephalus; 2) transtemporal gyrus approach, which exposes the inferolateral thalamus; and 3) transsylvian transinsular approach, which exposes the lateral thalamus (slightly more superiorly and posteriorly) and is advantageous for pathologies extending laterally into the peduncle, lenticular nucleus, or insula., Conclusions: Microsurgical approaches to thalamic gliomas continue to be challenging. Nonetheless, safe and effective cisternal, ventricular, and cortical corridors can be developed with thoughtful planning, anatomical understanding, and knowledge of the advantages, risks, and limitations of each approach. In some cases, it is wise to combine these approaches with staged procedures, as the authors demonstrate in Part 2. In Part 1 of this two-part series, they discuss thalamic microsurgical anatomy and illustrate the trajectory and exposures of all six approaches to guide decision-making. Part 2 discusses their thalamic glioma microsurgical case series, which utilizes these microsurgical approaches.

Background and Objectives: 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., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Purpose: This study aims to investigate the microsurgical anatomy of the superficial temporal artery (STA), explore the relationship between STA length and lumen diameter, and develop a reliable radiologic method for selecting STA segments for bypass surgery., Methods: This study used 10 cadaveric dissections (20 STAs, both sides) and 20 retrospective radiological examinations (40 STAs, both sides), employing curved multiplanar reformation and flow color lookup table (CLUT) DICOM processing. Measurements included vessel lumen diameters and luminal cross-sectional thicknesses 3 mm proximal to the STA bifurcation, 3 mm distal to the frontal branch, 5 cm distal to the frontal branch, 3 mm distal to the parietal branch, and 5 cm distal to the parietal branch. The distance between the STA bifurcation and the superior zygomatic border (SZB) was also measured. In our analysis, descriptive statistics encompassed mean, standard deviation (SD), standard error, minimum and maximum values, and distributions. Comparative statistics were performed using Student's t-test, with statistical significance set at p < 0.05., Results: There were no statistically significant differences between STA measurements of bifurcation distances (p = 0.88) and lumen diameters (p = 0.46) between cadavers and radiological measures. However, lumen thicknesses were larger in frontal branches than parietal branches at the seventh and eighth centimeter (p = 0.012, p = 0.039). Branches became thinner distally from the zygoma in both cadavers and radiological image measurements., Conclusion: The CLUT DICOM processing radiological measures provided the high-precision required to enable pre-surgical vessel selection for extracranial-intracranial bypass. The results show that STA vessel luminal diameters are sufficient (> 1 mm) for bypass surgery in the first 9 cm but gradually decrease after that. Also shown is that the choice of frontal versus parietal branches depends on individual anatomical features; therefore, careful preoperative radiological examination is critical., (© 2024. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Purpose: Proximity to critical neurovascular structures can create significant obstacles during surgical resection of foramen magnum meningiomas (FMMs) to the detriment of treatment outcomes. We propose a new classification that defines the tumor's relationship to neurovascular structures and assess correlation with postoperative outcomes., Methods: In this retrospective review, 41 consecutive patients underwent primary resection of FMMs through a far lateral approach. Groups defined based on tumor-neurovascular bundle configuration included Type 1, bundle ventral to tumor; Type 2a-c, bundle superior, inferior, or splayed, respectively; Type 3, bundle dorsal; and Type 4, nerves and/or vertebral artery encased by tumor., Results: The 41 patients (range 29-81 years old) had maximal tumor diameter averaging 30.1 mm (range 12.7-56 mm). Preoperatively, 17 (41%) patients had cranial nerve (CN) dysfunction, 12 (29%) had motor weakness and/or myelopathy, and 9 (22%) had sensory deficits. Tumor type was relevant to surgical outcomes: specifically, Type 4 demonstrated lower rates of gross total resection (65%) and worse immediate postoperative CN outcomes. Long-term findings showed Types 2, 3, and 4 demonstrated higher rates of permanent cranial neuropathy. Although patients with Type 4 tumors had overall higher ICU and hospital length of stay, there was no difference in tumor configuration and rates of postoperative complications or 30-day readmission., Conclusion: The four main types of FMMs in this proposed classification reflected a gradual increase in surgical difficulty and worse outcomes. Further studies are warranted in larger cohorts to confirm its reliability in predicting postoperative outcomes and possibly directing management decisions., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: Cranioplasty corrects cranial bone defects using various bone substitutes or autologous bone flaps created during a previous craniectomy surgery. These autologous bone flaps can be preserved through subcutaneous preservation (SP) or cryopreservation (CP)., Aim: We aim to compare outcomes and complications for both SP and CP techniques to enhance the current evidence about autologous bone flap preservation., Methods: Five electronic databases were searched to collect all relevant studies. Records were screened for eligibility. Data were extracted from the included studies independently. We categorized surgical site infection (SSI) as either due to Traumatic brain injury (TBI) or not to reveal potential variations in SSI incidence. The double-arm meta-analysis utilized risk ratios (RR) and mean differences (MD) with corresponding confidence intervals (CI) to pool categorical and continuous outcomes, respectively. Proportions with their respective 95% CIs were pooled for single-arm meta-analyses to determine outcomes related to SP technique., Results: Seventeen studies involving 1169 patients were analyzed. No significant difference in SSI rates was observed between SP and CP methods in patients with or without TBI. SP was linked to shorter hospital stays in two studies (194 patients). Single-arm analysis showed a 17% revision surgery rate across five studies (375 patients) and infection rates in 17 studies for SP. New bone formation occurred in 13.2% of patients, with 19.9% showing resorption., Conclusion: SP and CP methods showed similar SSI rates post-craniectomy in TBI and non-TBI patients. SP was associated with reduced hospitalization time, low infection rates, and a moderate need for revision surgery., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: The risk of recurrence is overestimated by the Kaplan-Meier method when competing events, such as death without recurrence, are present. Such overestimation can be avoided by using the Aalen-Johansen method, which is a direct extension of Kaplan-Meier that accounts for competing events. Meningiomas commonly occur in older individuals and have slow-growing properties, thereby warranting competing risk analysis. The extent to which competing events are considered in meningioma literature is unknown, and the consequences of using incorrect methodologies in meningioma recurrence risk analysis have not been investigated., Methods: We surveyed articles indexed on PubMed since 2020 to assess the usage of competing risk analysis in recent meningioma literature. To compare recurrence risk estimates obtained through Kaplan-Meier and Aalen-Johansen methods, we applied our international database comprising ~ 8,000 patients with a primary meningioma collected from 42 institutions., Results: Of 513 articles, 169 were eligible for full-text screening. There were 6,537 eligible cases from our PERNS database. The discrepancy between the results obtained by Kaplan-Meier and Aalen-Johansen was negligible among low-grade lesions and younger individuals. The discrepancy increased substantially in the patient groups associated with higher rates of competing events (older patients with high-grade lesions)., Conclusion: The importance of considering competing events in recurrence risk analysis is poorly recognized as only 6% of the studies we surveyed employed Aalen-Johansen analyses. Consequently, most of the previous literature has overestimated the risk of recurrence. The overestimation was negligible for studies involving low-grade lesions in younger individuals; however, overestimation might have been substantial for studies on high-grade lesions., (© 2024. The Author(s).)

Background and Objectives: In low- and middle-income countries (LMICs), approximately 5 million essential neurosurgical operations per year remain unaddressed. When compared with high-income countries, one of the reasons for this disparity is the lack of microsurgery training laboratories and neurosurgeons trained in microsurgical techniques. In 2020, we founded the Madison Microneurosurgery Initiative to provide no-cost, accessible, and sustainable microsurgery training opportunities to health care professionals from LMICs in their respective countries., Methods: We initially focused on enhancing our expertise in microsurgery laboratory training requirements. Subsequently, we procured a wide range of stereo microscopes, light sources, and surgical instrument sets, aiming to develop affordable, high-quality, and long-lasting microsurgery training kits. We then donated those kits to neurosurgeons across LMICs. After successfully delivering the kits to designated locations in LMICs, we have planned to initiate microsurgery laboratory training in these centers by providing a combination of live-streamed, offline, and in-person training assistance in their institutions., Results: We established basic microsurgery laboratory training centers in 28 institutions across 18 LMICs. This was made possible through donations of 57 microsurgery training kits, including 57 stereo microscopes, 2 surgical microscopes, and several advanced surgical instrument sets. Thereafter, we organized 10 live-streamed microanastomosis training sessions in 4 countries: Lebanon, Paraguay, Türkiye, and Bangladesh. Along with distributing the recordings from our live-streamed training sessions with these centers, we also granted them access to our microsurgery training resource library. We thus equipped these institutions with the necessary resources to enable continued learning and hands-on training. Moreover, we organized 7 in-person no-cost hands-on microanastomosis courses in different institutions across Türkiye, Georgia, Azerbaijan, and Paraguay. A total of 113 surgical specialists successfully completed these courses., Conclusion: Our novel approach of providing microsurgery training kits in combination with live-streamed, offline, and in-person training assistance enables sustainable microsurgery laboratory training in LMICs., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Hemangioblastomas are benign CNS tumors that can occur sporadically or in conjunction with von Hippel-Lindau disease. While 2% of spinal cord tumors are hemangioblastomas, combined cervical hemangioblastomas and pregnancy is rare. Some reports suggest that hemodynamic and hormonal changes in pregnancy might increase hemangioblastoma growth and aggravate symptoms. Urgent tumor removal is required when neurological problems deteriorate after failed symptomatic treatment. Neurosurgeons should collaborate with anesthesiologists and obstetricians in such cases. Herein, the authors present the first known video case of a sporadic cervical hemangioblastoma diagnosed during pregnancy that required urgent surgery due to failed symptomatic treatment and progressive clinical deterioration., Competing Interests: Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this publication.The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this publication., (© 2023, The Authors.)

Pain is strongly modulated by expectations and beliefs. Across species, subregions of ventromedial prefrontal cortex (VMPFC) are implicated in a variety of functions germane to pain, predictions, and learning. Human fMRI studies show that VMPFC activity tracks expectations about pain and mediates expectancy effects on pain-related activity in other brain regions. Prior lesion studies suggest that VMPFC may instead play a more general role in generating affective responses to painful stimuli. To test whether VMPFC is required to generate affective responses to pain or is more specifically involved in expectancy-based pain modulation, we studied responses to heat stimuli in five adults with bilateral surgical lesions of VMPFC and twenty healthy adults without brain damage. All participants underwent a quantitative sensory testing procedure followed by a pain expectancy task in which cues predicting either low or high pain were followed by intermittent medium intensity heat stimuli. Compared to adults without brain damage, individuals with VMPFC lesions reported larger differences in expected pain based on predictive cues and failed to update expectations following the covert introduction of unexpected medium temperature stimuli. Consistent with observed expectancy differences, subjective pain unpleasantness ratings in the VMPFC lesion group were more strongly modulated by cue during thermal stimulation. We found no group differences in overall pain sensitivity, nor in relationships between pain and autonomic arousal, suggesting that VMPFC damage specifically enhances the effect of expectations on pain processing, likely driven by impaired integration of new sensory feedback to update expectations about pain. These results provide essential new data regarding the specific functional contribution of VMPFC to pain modulation., Competing Interests: Declaration of competing interest Authors declare that they have no competing interests., (Published by Elsevier Ltd.)

Background  Neuroenteric cysts (NECs) are benign lesions mostly found as intradural extramedullary lesions in the cervicothoracic spinal cord. NECs in the cavernous sinus are very rare. To the best of our knowledge, this is only the second reported case and the first in an adult. Presentation  We present a left cavernous sinus NEC in a 75-year-old female with gradually worsening headache and facial pain unresponsive to medical treatment. Imaging revealed a cystic mass lesion in the left cavernous sinus encasing the distal petrosal and cavernous segment of the internal carotid artery. Initial differential diagnoses included more common pathologies located near the cavernous sinus, including cystic schwannoma, craniopharyngioma, and dermoid and epidermoid tumors. The patient underwent a left pterional craniotomy with an extradural transcavernous approach for surgical exploration and possible resection of this mass lesion. Histopathology revealed an NEC lined with benign respiratory-type epithelium. Postoperative imaging revealed gross total tumor resection. The patient remained neurologically intact with complete resolution of facial pain. Conclusion  We present a rare pathology that can easily be misinterpreted as other types of lesions. NECs should be kept in mind for differential diagnosis of cavernous sinus cystic lesions. The surgical aim should be maximal safe excision., Competing Interests: Conflict of Interest None declared., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. ( https://creativecommons.org/licenses/by-nc-nd/4.0/ ).)

Background: Pial arterial malformations (PAMs) are rare vascular lesions consisting of dilated tortuous arteries without venous drainage. Current PAM understanding is limited by the lesion's rarity, limited anatomopathological studies, and frequent misclassifications., Observations: A 23-year-old male experienced two spontaneous subarachnoid hemorrhages (SAHs) over 6 months with initially unremarkable diagnostic cerebral angiograms. Magnetic resonance imaging (MRI) and angiography after the second SAH revealed a small perimesencephalic ovoid lesion within the left crural cistern, between the left superior and posterior cerebral arteries, appearing to be an exophytic cavernoma, a thrombosed aneurysm, or a hemorrhagic tumor. Microsurgical resection was achieved with a pterional craniotomy and anterior clinoidectomy. The resected lesion was characteristic of a pure PAM arising from superior cerebellar arterial branches., Lessons: Small pure PAMs can be deceitfully dynamic lesions causing episodes of hemorrhage, complete thrombosis (angiographically occult), recanalization, and rehemorrhage. Small thrombosed vascular malformations or aneurysms should be included in differential diagnoses of angiographically occult SAH. MRI can be diagnostic, but the true angioarchitecture can only be elucidated with microneurosurgery. The only definitive cure is removal. The microneurosurgical strategy should account for worst-case scenarios, provide adequate skull base exposures, and include bypass revascularization options when thrombosed aneurysms are encountered.

Objective: Opening the roof of the interhemispheric microsurgical corridor to access various neurooncological or neurovascular lesions can be demanding because of the multiple bridging veins that drain into the sinus with their highly variable, location-specific anatomy. The objective of this study was to propose a new classification system for these parasagittal bridging veins, which are herein described as being arranged in 3 configurations with 4 drainage routes., Methods: Twenty adult cadaveric heads (40 hemispheres) were examined. From this examination, the authors describe 3 types of configurations of the parasagittal bridging veins relative to specific anatomical landmarks (coronal suture, postcentral sulcus) and their drainage routes into the superior sagittal sinus, convexity dura, lacunae, and falx. They also quantify the relative incidence and extension of these anatomical variations and provide several preoperative, postoperative, and microneurosurgical clinical case study examples., Results: The authors describe 3 anatomical configurations for venous drainage, which improves on the 2 types that have been previously described. In type 1, a single vein joins; in type 2, 2 or more contiguous veins join; and in type 3, a venous complex joins at the same point. Anterior to the coronal suture, the most common configuration was type 1 dural drainage, occurring in 57% of hemispheres. Between the coronal suture and the postcentral sulcus, most veins (including 73% of superior anastomotic veins of Trolard) drain first into a venous lacuna, which are larger and more numerous in this region. Posterior to the postcentral sulcus, the most common drainage route was through the falx., Conclusions: The authors propose a systematic classification for the parasagittal venous network. Using anatomical landmarks, they define 3 venous configurations and 4 drainage routes. Analysis of these configurations with respect to surgical routes indicates 2 highly risky interhemispheric surgical fissure routes. The risks are attributable to the presence of large lacunae that receive multiple veins (type 2) or venous complex (type 3) configurations that negatively impact a surgeon's working space and degree of movement and thus are predisposed to inadvertent avulsions, bleeding, and venous thrombosis.

Background: The main access route for middle cerebral artery (MCA) aneurysms is the transsylvian approach. Although Sylvian fissure (SF) variations have been assessed, none have examined how this affects MCA aneurysm surgery. The objective of this study is to investigate how SF variants affect clinical and radiological outcomes for surgically-treated unruptured MCA aneurysms., Methods: This retrospective study examined consecutive unruptured MCA aneurysms in 101 patients undergoing SF dissection and aneurysm clipping. SF anatomical variants were categorized using a novel functional anatomical classification: Type I: Wide straight, Type II: Wide with frontal and/or temporal opercula herniation, Type III: Narrow straight, and Type IV: Narrow with frontal and/or temporal opercula herniation. The relationships between SF variants and postoperative edema, ischemia, hemorrhage, vasospasm, and Glasgow Outcome Scale (GOS) were analyzed., Results: Study included 101 patients (53.5% women), 60.9 ± 9.4 (range 24-78) years. SF types were 29.7% Type I, 19.8% Type II, 35.6% Type III, and 14.9% Type IV. The SF type with the highest proportion of females was Type IV (n = 11, 73.3%), while it was Type III for males (n = 23, 63.9%) (P = 0.03). There were significant differences between SF types, ischemia, and edema (P < 0.001, P = 0.008, respectively). Although narrow SF types had poorer GOS scores (P = 0.055), there were no significant differences between SF types and GOS, postoperative hemorrhage, vasospasm, or hospital stay., Conclusions: Sylvian fissure variants may impact intraoperative complications during aneurysm surgery. Thus, presurgical determination of SF variants can predict surgical difficulties, thereby potentially reducing morbidity for patients with MCA aneurysms and other pathologies requiring SF dissection., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Intracranial germinomas are most commonly extra-axial germ cell tumors that are predominantly found in the pineal and suprasellar regions. Primary intra-axial midbrain germinomas are extremely rare, with only eight reported cases. Here we present a 30-year-old man who presented with severe neurological deficits, with an MRI that showed a heterogeneously enhancing mass with ill-defined margins in the midbrain, and with surrounding vasogenic edema extending to the thalamus. The presumptive preoperative differential diagnosis included glial tumors and lymphoma. The patient underwent a right paramedian suboccipital craniotomy and biopsy obtained through the supracerebellar infratentorial transcollicular approach. The histopathological diagnosis was reported as pure germinoma. After patient discharge, he received chemotherapy with carboplatin and etoposide, followed by radiotherapy. Follow-up MRI at up to 26 months showed no contrast-enhancing lesions but a mild T2 FLAIR hyperintensity adjacent to the resection cavity. Differential diagnosis of midbrain lesions can be challenging and should include glial tumors, primary central nervous system lymphoma, germ cell tumors, and metastasis. Accurate diagnosis requires adequate tissue sampling. In this report, we present a very rare case of a primary intra-axial germinoma of the midbrain which is biopsied via a transcollicular approach. This report is also unique as it provides the first surgical video of an open biopsy and the microscopic appearance of an intra-axial primary midbrain germinoma via a transcollicular approach., Competing Interests: Conflict of interest The senior author (MKB) declares that he is a Stryker consultant. All other authors declare no competing interests., (Copyright © 2023. Published by Elsevier B.V.)

Background: Dural arteriovenous fistulas (dAVFs) located at craniocervical junction are extremely rare (1%-2% of intracranial/spinal dAVFs). Their angio-architectural complexity renders endovascular embolization to be challenging given multiple small feeders with risk of embolysate reflux into vertebral artery and limited transvenous access. The available literature discussing microsurgery for these lesions is limited to few case reports., Objective: To report a multicenter experience assessing microsurgery safety/efficacy., Methods: Prospectively maintained registries at 13 North American centers were queried to identify craniocervical junction dAVFs treated with microsurgery (2006-2021)., Results: Thirty-eight patients (median age 59.5 years, 44.7% female patients) were included. The most common presentation was subarachnoid/intracranial hemorrhage (47.4%) and myelopathy (36.8%) (92.1% of lesions Cognard type III-V). Direct meningeal branches from V3/4 vertebral artery segments supplied 84.2% of lesions. All lesions failed (n = 5, 13.2%) or were deemed inaccessible/unsafe to endovascular treatment. Far lateral craniotomy was the most used approach (94.7%). Intraoperative angiogram was performed in 39.5% of the cases, with angiographic cure in 94.7% of cases (median imaging follow-up of 9.2 months) and retreatment rate of 5.3%. Favorable last follow-up modified Rankin Scale of 0 to 2 was recorded in 81.6% of the patients with procedural complications of 2.6%., Conclusion: Craniocervical dAVFs represent rare entity of lesions presenting most commonly with hemorrhage or myelopathy because of venous congestion. Microsurgery using a far lateral approach provides robust exposure and visualization for these lesions and allows obliteration of the arterialized draining vein intradurally as close as possible to the fistula point. This approach was associated with a high rate of angiographic cure and favorable clinical outcomes., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Brain metastases are a challenging manifestation of renal cell carcinoma. We have a limited understanding of brain metastasis tumor and immune biology, drivers of resistance to systemic treatment, and their overall poor prognosis. Current data support a multimodal treatment strategy with radiation treatment and/or surgery. Nonetheless, the optimal approach for the management of brain metastases from renal cell carcinoma remains unclear. To improve patient care, the authors sought to standardize practical management strategies. They performed an unstructured literature review and elaborated on the current management strategies through an international group of experts from different disciplines assembled via the network of the International Kidney Cancer Coalition. Experts from different disciplines were administered a survey to answer questions related to current challenges and unmet patient needs. On the basis of the integrated approach of literature review and survey study results, the authors built algorithms for the management of single and multiple brain metastases in patients with renal cell carcinoma. The literature review, consensus statements, and algorithms presented in this report can serve as a framework guiding treatment decisions for patients. CA Cancer J Clin. 2022;72:454-489., (© 2022 The Authors. CA: A Cancer Journal for Clinicians published by Wiley Periodicals LLC on behalf of American Cancer Society.)

Carefully preserving facial nerve function is crucial when using the translabyrinthine approach for vestibular schwannoma surgery. Nerve preservation can only be accomplished by employing rigorous surgical methods and having a thorough understanding of the relevant anatomy, including any variations. Anatomical variations in the path of the facial nerve are infrequent but are most commonly encountered in association with congenital abnormalities of the temporal bone or ossicles. We present a rare case of vestibular schwannoma with a bifurcated facial nerve having 2 origins at the brainstem. The patient underwent a right-sided microsurgical excision using the right translabyrinthine approach. Postoperative recovery went smoothly, resulting in a House-Brackmann scale of Grade I. This case emphasizes the importance of identifying and preserving the facial nerve during vestibular schwannoma resection. To avoid injury, intraoperative neurostimulation should be used to positively identify the facial nerve and its anatomical variations along its entire course., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Gliomas are common brain tumors with a variable prognosis based on their tumor grade. With glioblastomas, the prognosis is usually unfavorable. Thus, having accurate and rapid methods for their diagnosis and follow-up are essential for rapid discovery of the tumor and to protect patients from unnecessary procedures. Some glioma cases are challenging since there is a limited ability to differentiate between gliomas, recurrent glioblastomas, and single metastatic lesions. Monitoring treatment responses and follow-ups can also be challenging. While both radiological and serological markers have been identified that can aid diagnosis and assess therapies, a particularly promising new class of serological markers are long non-coding RNAs. Long non-coding RNAs are a relatively recently discovered class of regulatory RNA molecules that play critical roles in many cellular and physiological processes. The potential role that long non-coding RNAs play with glioma pathogenic processes is not fully understood. In this literature review, we highlight the potential for long non-coding RNAs to be used as serum biomarkers in glioblastoma patients, including their potential to serve as non-invasive, easy to use, and rapid diagnostic or prognostic indicators., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s). Published by IMR Press.)

Compressive syndromes of the cervical arteries caused by musculoskeletal structures include bow hunter's syndrome, beauty parlour stroke syndrome, carotid compression by the hyoid bone, carotid compression by the digastric muscle and Eagle syndrome. They are a rare but increasingly recognised group of syndromes, so a high level of suspicion is needed so the diagnosis is not missed. The diagnosis is typically based on a combination of clinical history and advanced imaging investigations. Compression of the arteries may be static (only provoked by compression) or dynamic (exaggerated by movement), and this should be considered when selecting imaging studies. Symptoms resulting from vertebrobasilar insufficiency or ischaemia of areas supplied by the internal carotid artery are caused by compression of the vertebral artery and the internal carotid artery respectively. Surgical procedures are the preferred treatment for most of these syndromes.

Functional resonance magnetic imaging (fMRI) allows for identification of eloquent cortex in pre-treatment planning. Previous studies have shown a correlation among lesion to activation distance (LAD) measures and morbidity and mortality. This study investigates the relationship between LAD, well-established language centers (Wernicke's and Broca's), and language performance measures. We included a sample population of brain tumor patients that received language fMRI (verbal fluency and sentence verification) for pre-treatment assessment (n = 51). LAD to the nearest language area was measured and divided into groups ≤ 10 mm and > 10 mm. Verbal fluency scores were compared between these groups. Additionally, patients were divided into similar groups based on LAD to either Broca's or Wernicke's areas, and the verbal fluency scores and sentence verification accuracy (n = 29) were subsequently compared between groups. Brain tumor patients with LAD ≤ 10 mm to either language area had significantly lower verbal fluency scores (p = 0.028). The difference in verbal fluency scores between groups with LAD ≤ 10 mm and > 10 mm to Wernicke's area trends toward significance (p = 0.067). The sentence verification accuracy was significantly lower in patients with LAD ≤ 10 mm to either language area (p = 0.039). These findings suggest that there exists a significant relationship between LAD to language centers and measures; greater language deficits are seen when LAD ≤ 10 mm., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Background: Poor-grade aneurysmal subarachnoid hemorrhage (PGASAH) is associated with high mortality and morbidity regardless of treatment. Herein, we re-evaluate the safety and efficacy of microsurgical treatment for managing PGASAH patients in the current endovascular era., Methods: We retrospectively reviewed 141 consecutive patient records in a single institution who underwent microsurgical (n = 80) or endovascular (n = 61) treatment for PGASAH., Results: Baseline characteristics were similar, except for more intracerebral hematomas (46.3% vs 24.6%, p = 0.009), fewer intraventricular hemorrhages (26.3% vs 59%, p < 0.001), and fewer posterior circulation aneurysms (5.1% vs 44.3%, p < 0.001) in the microsurgery group. Decompressive craniectomy (58.5% vs 24.6%, p < 0.001) and shunt-dependent hydrocephalus (63.7% vs 41%, p = 0.01) were more common for microsurgery, while procedural ischemic complications were less common (5% vs 24.6%, p = 0.001). Both early (12.5% vs 32.8%, p = 0.006) and late mortality rates (22.5% vs 39.3%, p = 0.041) were lower for microsurgery, and favorable 12-month outcomes (modified Rankin scale = 0-2) were better (62.5% vs 42.6%, p = 0.026). Multivariate analysis revealed that advanced age, neurological grade, modified Fisher grade, larger aneurysm size, rebleeding, and cerebral infarctions were independent predictors of poor outcome. Microsurgery fared marginally better than endovascular treatment (OR: 2.630, 95% CI: [0.991-6.981], p = 0.052)., Conclusions: Timely and efficient treatment, either via open microsurgery or endovascular surgery, provided favorable outcomes for over half of PGASAH patients in this series. Therefore, early treatment should be offered to all PGASAH patients regardless of clinical and/or radiological factors. Microsurgery remains an effective treatment modality for selected PGASAH patients in the endovascular era., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: The temporal bone is difficult to comprehend in three-dimensional (3D) space. We provide a novel 3D mental model of the temporal bone which helps clinicians and surgeons dealing with it in teaching, diagnosing, conservative managements, and preoperative and intraoperative orientation. This study is part of the scientific project Brainatomy., Objective: To analyze and simplify the temporal bone anatomy to enhance its comprehension and long-term retention., Methods: The study was conducted at the Neurosurgical Department of the University Hospital of Bochum, Germany. We retrospectively analyzed data sets of 221 adult patients who underwent computed tomography (CT) of the skull (n = 167) and magnetic resonance imaging (MRI) of the brain (n = 54). A total of 142 patients with their respective imaging scans remained in our pool of interest after excluding 79 scans. The raw digital imaging and communications in medicine scans were transformed into 3D objects. Spatial analyses were then conducted, and all collected data were used to create our own 3D model of the temporal bone., Results: We define the temporal bone as a prism-shaped model and divide it into 6 compartments: apex, neurovascular, mastoid, blank, tympanic, and temporomandibular compartments. The division into compartments has been achieved with the "Rule of 3-2-1." Finally, the 3D model has been used to record a video (Video), using a novel and "easy-to-follow" didactic approach., Conclusion: This simplified 3D model along with the corresponding video (Video) potentially enhances the efficiency of studying temporal none anatomy with a novel "easy-to-follow" approach., (Copyright © Congress of Neurological Surgeons 2021. All rights reserved.)

Posterior circulation aneurysms have a higher tendency to rupture and become symptomatic in comparison to anterior circulation aneurysms. Current treatment modalities for aneurysms in these locations vary widely including microsurgical clipping, trapping with bypass, wrapping, and various endovascular methods such as coiling, balloon or stent-assisted coiling, flow diversion, and vessel sacrifice, among others.Overall, surgical versus endovascular treatment of posterior circulation aneurysms continue to be a controversial topic in cerebrovascular neurosurgery. At our center, multi-disciplinary assessments including surgeons capable of both endovascular and microsurgical treatments of these aneurysms are employed to guide the treatment strategies. As advancements in both fields are made, this will continue to be a topic for debate. Anatomy and individual patient's characteristics will dictate the correct approach and therefore proficiency in the microsurgical techniques required to treat these aneurysms will continue to be both relevant and important., (© 2022. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Although outcome studies and systematic reviews have been published on the surgical treatment of third ventricle colloid cysts (TVCC), there are no meta-analyses that compare the outcomes for various surgical approaches. This meta-analysis assesses the outcomes and complications for transcortical, transcallosal, and endoscopic surgical approaches used to excise TVCCs. A meta-analysis of surgically excised TVCCs was performed with an assessment of outcome for transcortical, transcallosal, and endoscopic approaches. A random-effects model analyzed the extent of surgical excision. The analysis included reports that compared at least two of these surgical approaches, for a total of 11 studies comprising a population of 301 patients. The transcortical approach was associated with a higher incidence of complete excision compared to the endoscopic approach (OR = 0.137, p = 0.041), with no significant differences observed between transcortical and transcallosal approaches, and between transcallosal and endoscopic approaches. Comparison between endoscopic and pooled microsurgical approaches was also insignificant (OR = 0.22, p = 1). The risk of motor weakness was increased with the transcortical approach compared to the endoscopic approach (OR = 6.10, p = 0.018). There were no significant differences between transcortical and transcallosal approaches regarding newly onset seizures, and no significant mortality differences between all three approaches. This study demonstrates that microsurgical approaches are associated with a greater extent of resection compared to endoscopic approaches; however, best results are likely achieved based on the surgeon's expertise, flexibility, and case review., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.)

Objective: Suprasellar meningioma resection via either the transcranial approach (TCA) or the endoscopic endonasal approach (EEA) is an area of controversy and active evaluation. Skull base surgeons increasingly consider patient-reported outcomes (PROs) when choosing an approach. No PRO measure currently exists to assess quality of life for suprasellar meningiomas., Methods: Adult patients undergoing suprasellar meningioma resection between 2013 and 2019 via EEA (n = 14) or TCA (n = 14) underwent semistructured interviews. Transcripts were coded using a grounded theory approach to identify themes as the basis for a PRO measure that includes all uniquely reported symptoms. To assess content validity, 32 patients and 15 surgeons used a Likert scale to rate the relevance of items on the resulting questionnaire and the general Patient-Reported Outcomes Measurement Information System-29 (PROMIS29). The mean scores were calculated for all items and compared for TCA versus EEA patient cohorts by using unpaired t-tests. Items on either questionnaire with mean scores ≥ 2.0 from patients were considered meaningful and were aggregated to form the novel Suprasellar Meningioma Patient-Reported Outcome Survey (SMPRO) instrument., Results: Qualitative analyses resulted in 55 candidate items. Relative to patients who underwent the EEA, those who underwent the TCA reported significantly worse future outlook before surgery (p = 0.01), tiredness from medications 2 weeks after surgery (p = 0.001), and word-finding and memory difficulties 3 months after surgery (p = 0.05 and < 0.001, respectively). The items that patients who received a TCA were most concerned about included medication-induced lethargy after surgery (2.9 ± 1.3), blurry vision before surgery (2.7 ± 1.5), and difficulty reading due to blurry vision before surgery (2.7 ± 2.7). Items that patients who received an EEA were most concerned about included blurry vision before surgery (3.5 ± 1.3), difficulty reading due to blurry vision before surgery (2.4 ± 1.3), and problems with smell postsurgery (2.9 ± 1.3). Although surgeons overall overestimated how concerned patients were about questionnaire items (p < 0.0005), the greatest discrepancies between patient and surgeon relevance scores were for blurry vision pre- and postoperatively (p < 0.001 and < 0.001, respectively) and problems with taste postoperatively (p < 0.001). Seventeen meningioma-specific items were considered meaningful, supplementing 8 significant PROMIS29 items to create the novel 25-item SMPRO., Conclusions: The authors developed a disease- and approach-specific measure for suprasellar meningiomas to compare quality of life by operative approach. If demonstrated to be reliable and valid in future studies, this instrument may assist patients and providers in choosing a personalized surgical approach.

Objective  The carotico-clinoid foramen and interclinoid bridge are two anatomical variants of the sellar region. If these anatomical variants go unrecognized and are not managed safely by the surgeon during expanded endoscopic endonasal surgery for a posterior clinoidectomy, a carotid artery injury may occur. We summarize a method to safely navigate in the presence of the carotico-clinoid foramen and interclinoid bridge in an endoscopic endonasal approach. Study Design  The study involves cadaveric dissection and management of the anatomical variants. Setting  The study took place in a cadaveric dissection laboratory. Participants  The object of study is one cadaveric head. Main Outcome Measures  After discovering the two variants in both cavernous sinuses of a cadaveric head, we established a stepwise coping strategy to avoid carotid artery injury while performing an endoscopic endonasal bilateral interdural pituitary transposition, and we report the final view after endoscopic management. Results  Debulking of the middle clinoid process can decrease the obstacle effect, and the pituitary transposition can be performed medial to the ossified carotico-clinoid ligament. Disconnection of the interclinoid bridge is the prerequisite to an effective posterior clinoidectomy, and distinguishing the transition between the sellar diaphragm and the interclinoid bridge is essential. Conclusion  In the presence of both the carotico-clinoid foramen and the interclinoid bridge, a bilateral interdural pituitary transposition can still be performed, although preoperative strategic preparation, full inspection, and stepwise disconnections are of paramount importance in such a scenario to avoid cavernous carotid artery injury., Competing Interests: Conflict of Interest A.S.L. is an investor in Kogent Surgical and has stock options in SPIWay. P.N. has a consulting and royalty relationship in Osteomed, Inc. and holds stock in GT Medical Technologies. All the other authors report no conflict of interest., (Thieme. All rights reserved.)

The paramedian supracerebellar transtentorial approach allows unobstructed exposure to the quadrigeminal cistern, tectal plate, pineal region, tentorial incisura, medial basal temporal lobe, and posterior ambient cistern. The authors present a meningioma of the posterolateral tentorial incisura case in a 62-year-old male who presented with a long history of upper-extremity tremors and walking difficulties. MRI revealed supra- and infratentorial tumor extension and hydrocephalus. This approach enabled us to achieve gross-total resection without causing neurovascular injury or any postoperative neurological deficits. For each pathology, the pros and cons of various approaches should be considered based on the anatomy, vasculature, and any surrounding structures. The video can be found here: https://stream.cadmore.media/r10.3171/2021.4.FOCVID2138., Competing Interests: Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this publication., (© 2021, The Authors.)

Introduction  Meningiomas are among the most common primary intracranial tumors. While well-described, there is limited information on the outcomes and consequences following treatment of giant-sized vertex-based meningiomas. These meningiomas have specific risks and potential complications due to their size, location, and involvement with extracalvarial soft tissue and dural sinuses. Herein, we present four giant-sized vertex transosseous meningioma cases with involvement and occlusion of the sagittal sinus, that postoperatively developed external hydrocephalus and ultimately required shunting. Methods  A retrospective chart review identified patients with large vertex meningiomas that were: (1) large (>6 cm) with hemispheric (no skull base) location, (2) involvement of the superior sagittal sinus resulting in complete sinus occlusion, (3) involvement of dura resulting in a large duraplasty area, (4) transosseous involvement requiring a 5 cm or larger craniectomy for resection of invaded calvarial bone. Results  Tumors were resected in all four cases, with all patients subsequently developing external hydrocephalus which required shunting within 2 weeks to 6 months postsurgery. Conclusion  We believe this may be the first report of the development of hydrocephalus following surgical resection of these large lesions. Based on our observations, we propose that a combination of superior sagittal sinus occlusion and changes in brain elasticity and compliance affect the brain's CSF absorptive capacity, which ultimately lead to hydrocephalus development. We suggest that neurosurgeons be aware that postoperative hydrocephalus can quickly develop following treatment of giant-sized vertex-based meningiomas, and that correction of hydrocephalus with shunting can readily be achieved., Competing Interests: Conflict of Interest None declared., (Thieme. All rights reserved.)

Chondrosarcomas are one of the major malignant neoplasms which occur at the skull base. These tumors are locally invasive. Gross total resection of chondrosarcomas is associated with longer progression-free survival rates. The patient is a 55-year-old man with a history of dysphagia, left eye dryness, hearing loss, and left-sided facial pain. Magnetic resonance imaging (MRI) showed a giant heterogeneously enhancing left-sided skull base mass within the cavernous sinus and the petrous apex with extension into the sphenoid bone, clivus, and the cerebellopontine angle, with associated displacement of the brainstem ( Fig. 1 ). An endoscopic endonasal biopsy revealed a grade-II chondrosarcoma. The patient was then referred for surgical resection. Computed tomography (CT) scan and CT angiogram of the head and neck showed a left-sided skull base mass, partial destruction of the petrous apex, and complete or near-complete occlusion of the left internal carotid artery. Digital subtraction angiography confirmed complete occlusion of the left internal carotid artery with cortical, vertebrobasilar, and leptomeningeal collateral development. The decision was made to proceed with a left-sided transcavernous approach with possible petrous apex drilling. During surgery, minimal petrous apex drilling was necessary due to autopetrosectomy by the tumor. Endoscopy was used to assist achieving gross total resection ( Fig. 2 ). Surgery and postoperative course were uneventful. MRI confirmed gross total resection of the tumor. The histopathology was a grade-II chondrosarcoma. The patient received proton therapy and continues to do well without recurrence at 4-year follow-up. This video demonstrates steps of the combined microsurgical skull base approaches for resection of these challenging tumors. The link to the video can be found at: https://youtu.be/WlmCP&#95;-i57s ., Competing Interests: Conflict of Interest None declared., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. ( https://creativecommons.org/licenses/by-nc-nd/4.0/ ).)

Surgical treatment of giant aneurysms often poses significant challenges. Endovascular techniques have evolved exponentially over the last decades, and most of these complex aneurysms can be treated with flow-diverting techniques; however, successful obliteration of all giant aneurysms is not always possible with endovascular flow-diverting techniques. Although the need for microsurgical intervention has undoubtedly diminished, a versatile-thinking surgeon should keep in mind that obliteration of these aneurysms combined with revascularizing the distal circulation via extracranial-intracranial bypass techniques can provide a potentially life-long durable solution. The key to curing these pathologies is to utilize interdisciplinary decision making with a robust knowledge of the pros and cons of different treatment approaches. Herein, we present a case of a giant posterior communicating segment aneurysm of the left supraclinoid internal carotid artery (ICA), which was treated by obliteration ( Fig. 1 ). Extradural anterior clinoidectomy was used to provide exposure of the supraclinoidal ICA proximal to the aneurysm, and revascularization of the distal circulation was achieved with a common carotid artery to M2-superior trunk bypass using a radial artery interposition graft ( Fig. 2 ). The patient was a 62-year-old female who presented with vision loss in her left eye but was otherwise neurologically intact. She had a history of two unsuccessful flow-diverting stent placement attempts 2 months prior to this surgery. Postoperatively, the patient woke up without any deficits, with her left eye vision partially recovered and ultimately returning to normal at 1-year follow-up. Computed tomography (CT) angiography at a 1-year follow-up showed complete obliteration of the aneurysm and successful revascularization of the distal circulation. The link to the video can be found at: https://youtu.be/DsIuIJJj1l4 ., Competing Interests: Conflict of Interest None declared., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. ( https://creativecommons.org/licenses/by-nc-nd/4.0/ ).)

Microsurgery of cavernous sinus (CS) lesions is generally considered to be associated with a high rate of morbidity and cranial nerve deficits. The success for surgical removal of CS meningiomas is debatable and achieving a good functional outcome with preservation of the cranial nerves is the goal. Surgery of these lesions is challenging, recurrence rates are high, and therapeutic strategies remain controversial. In this video, we present a case of a CS meningioma that extended to Meckel's cave and the posterior fossa in a 46-year-old woman with history of a left-sided cerebellopontine angle World Health Organization (WHO) grade-I meningioma with extension to the left CS. Seven years ago, she had a microsurgical resection of a Cerebellopontine angle (CPA) meningioma. She later received radiotherapy for the slowly growing meningioma of the posterior CS. The patient presented with newly onset headache and facial pain. Magnetic resonance imaging (MRI) showed a meningioma of the left CS and Meckel's cave extending into the ambient cistern, with a mild mass effect on the pons, and a size increase compared with prior imaging. Since this area previously received radiotherapy, and the patient was symptomatic from trigeminal compression, the decision was made to proceed with surgical resection of the tumor via combined transcavernous and anterior petrosectomy. Postoperatively, the patient woke up with the same neurological status. MRI confirmed gross total resection of the tumor. The histopathology was a WHO grade-II chordoid meningioma. The patient is currently receiving radiotherapy. This video demonstrates the surgical approach and the resection steps of this pathology. The link to the video can be found at: https://youtu.be/HrU1VOzUGWU ., Competing Interests: Conflict of Interest None declared., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. ( https://creativecommons.org/licenses/by-nc-nd/4.0/ ).)

Fusiform or near-fusiform aneurysms that involve the long segment of the supraclinoid internal carotid artery (ICA) pose significant challenges to neurovascular surgeons. Involvement of the origin of vital branching arteries in this segment may preclude safe treatment with flow diverting stents. In addition, clip reconstruction may also not be possible in this region due to entire or near-entire involvement of the circumference of the ICA ( Fig. 1 ). In this video article, we present a case of a complex and previously leaked, (visualized with hemosiderin) aneurysm of the posterior communicating segment of the ICA, in a 60-year-old female. Multiple complexities made this aneurysm challenging to treat. These included (1) a 270-degree encirclement of the ICA with multiple lobulations that left only a small section of nondiseased vessel wall, (2) a relatively short segment of the supraclinoidal ICA that made proximal control challenging thus requiring an extradural anterior clinoidectomy, (3) a fetal posterior communicating artery that originated immediately proximal to the beginning of the aneurysm, and lastly, (4) an anterior choroidal artery that was firmly adherent over the aneurysm dome. In this video, we present the microsurgical steps for dealing with this complex aneurysm, including extradural clinoidectomy and clip reconstruction ( Fig. 2 ). Postoperatively, the patient woke up without any deficits. Angiography showed complete obliteration of the aneurysm. The link to the video can be found at: https://youtu.be/3Zz-ecvlDIc ., Competing Interests: Conflict of Interest None declared., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. ( https://creativecommons.org/licenses/by-nc-nd/4.0/ ).)

Trigeminal neuralgia (TN) is most commonly caused by neurovascular compression of the superior cerebellar artery. We present the first reported TN case where nerve compression was caused by the petrous internal carotid artery in the vicinity of a Meckel cave (MC) encephalocele. The patient underwent a pterional craniotomy for decompression of the gasserian ganglion and trigeminal nerve branches. All symptoms were resolved post surgery. We surmise that the principal cause of the TN was vascular compression from an exposed petrous internal carotid artery in the presence of an encephalocele. Causation was irrespective of whether the dehiscence in the petrous apex was a congenital defect or associated with destruction from the encephalocele. Based on this observation, we recommend that surgeons carefully consider all possible causes of patient symptoms as they prepare a meticulous dissection plan to avoid damage to surrounding neurovascular structures., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Although intravenous digital subtraction angiography (IV-DSA), cone-beam CT, and rotational angiography are well-established technologies, using them in a single system in the hybrid operating room to acquire high-quality noninvasive 3D images is a recent development. This video demonstrates microsurgical excision of a ruptured cerebellar arteriovenous malformation (AVM) in a 66-year-old male followed by intraoperative IV-DSA acquisition using a new-generation system (Artis Icono). IV-DSA confirmed in real time that no residual remained following excision without the need to reposition the patient. To the best of the authors' knowledge, this is the first surgical video to demonstrate the simplified workflow and application of this technology in neurovascular surgery. The video can be found here: https://youtu.be/bo5ya9DQQPw., Competing Interests: Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this publication., (© 2021 The Authors.)