An interdisciplinary consensus on the management of brain metastases in patients with renal cell carcinoma.

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.

The importance of considering competing risks in recurrence analysis of intracranial meningioma.

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.

Novel classification of foramen magnum meningiomas predicted by topographic position relative to neurovascular bundle.

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.

Angiographic measurement of the superficial temporal artery for potential use in cerebral bypass surgery: a combined radiological and cadaveric study.

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.

Posterior Circulation Aneurysms.

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.

The role of microsurgery for poor-grade aneurysmal subarachnoid hemorrhages in the endovascular era.

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.

Serum long non-coding RNAs as potential noninvasive biomarkers for glioblastoma diagnosis, prognosis, and chemoresistance.

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.

Surgical approaches for resection of third ventricle colloid cysts: meta-analysis.

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.

High-resolution diffusion tensor magnetic resonance imaging of the brainstem safe entry zones.

Operative management of intrinsic brainstem lesions remains challenging despite advances in electrophysiological monitoring, neuroimaging, and neuroanatomical knowledge. Surgical intervention in this region requires detailed knowledge of adjacent critical white matter tracts, brainstem nuclei, brainstem vessels, and risks associated with each surgical approach. Our aim was to systematically verify internal anatomy associated with each brainstem safety entry zone (BSEZ) via neuroimaging modalities commonly used in pre-operative planning, namely high-resolution magnetic resonance imaging (MRI) and diffusion tensor tractography (DTT). Twelve BSEZs were simulated in eight, formalin-fixed, cadaveric brains. Specimens then underwent radiological investigation including T2-weighted imaging and DTT using 4.7 T MRI to verify internal anatomic relationships between simulated BSEZs and adjacent critical white matter tracts and nuclei. The distance between simulated BSEZs and pre-defined, adjacent critical structures was systemically recorded. Entry points and anatomic limits on the surface of the brainstem are described for each BSEZ, along with description of potential neurological sequelae if such limits are violated. With high-resolution imaging, we verified a maximal depth for each BSEZ. The relationship between proposed safe entry corridors and adjacent critical structures within the brainstem is quantified. In combination with tissue dissection, high-resolution MR diffusion tensor imaging allows the surgeon to develop a better understanding of the internal architecture of the brainstem, particularly as related to BSEZs, prior to surgical intervention. Through a careful study of such imaging and use of optimal surgical corridors, a more accurate and safe surgery of brainstem lesions may be achieved.

Surgical management of craniopharyngiomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section.

BACKGROUND AND OBJECTIVE: Craniopharyngiomas are locally aggressive neuroepithelial tumors infiltrating nearby critical neurovascular structures. The majority of published surgical series deal with childhood-onset craniopharyngiomas, while the optimal surgical management for adult-onset tumors remains unclear. The aim of this paper is to summarize the main principles defining the surgical strategy for the management of craniopharyngiomas in adult patients through an extensive systematic literature review in order to formulate a series of recommendations. MATERIAL AND METHODS: The MEDLINE database was systematically reviewed (January 1970-February 2019) to identify pertinent articles dealing with the surgical management of adult-onset craniopharyngiomas. A summary of literature evidence was proposed after discussion within the EANS skull base section. RESULTS: The EANS task force formulated 13 recommendations and 4 suggestions. Treatment of these patients should be performed in tertiary referral centers. The endonasal approach is presently recommended for midline craniopharyngiomas because of the improved GTR and superior endocrinological and visual outcomes. The rate of CSF leak has strongly diminished with the use of the multilayer reconstruction technique. Transcranial approaches are recommended for tumors presenting lateral extensions or purely intraventricular. Independent of the technique, a maximal but hypothalamic-sparing resection should be performed to limit the occurrence of postoperative hypothalamic syndromes and metabolic complications. Similar principles should also be applied for tumor recurrences. Radiotherapy or intracystic agents are alternative treatments when no further surgery is possible. A multidisciplinary long-term follow-up is necessary.

Mapping of the internal capsule with subcortical stimulation for gross-total resection of a thalamic metastatic tumor.

Although the surgical treatment of thalamic tumors remains challenging due to the proximity to the internal capsule, safe resection of gliomas or metastatic tumors of the thalamus are possible in some selected cases due to a better understanding of microsurgical anatomy and due to advances in neurophysiological mapping and monitoring. In this video, the authors demonstrate the use of mapping of the internal capsule with direct subcortical stimulation for the resection of a metastatic tumor. The patient is a 58-year-old man with a history of renal cell carcinoma and metastasis in the left thalamus and parieto-occipital region. He underwent stereotactic radiation of both tumors at an outside hospital. Due to the increased size of both tumors and surrounding vasogenic edema, he was referred to the authors for resection. He underwent gross-total resection via an interhemispheric transcallosal approach. His postoperative course was uneventful and did not have any focal neurological deficits, including motor, sensory, or visual functions. The authors' surgical approach to this metastatic thalamic tumor and the intraoperative real-time direct subcortical stimulation of the internal capsule during surgery are demonstrated in this video. The video can be found here: https://youtu.be/DmDxjJUSZWU .

Facial nerve outcome and extent of resection in cystic versus solid vestibular schwannomas in radiosurgery era.

OBJECTIVE Cystic vestibular schwannomas (CVSs) are a subgroup of vestibular schwannomas (VSs) that are reported to be associated with unpredictable clinical behavior and unfavorable postoperative outcomes. The authors aimed to review their experience with microsurgical treatment of CVSs in terms of extent of resection and postoperative facial nerve (FN) function and compare these outcomes with those of their solid counterparts. METHODS Two hundred-eleven VS patients were treated surgically between 2006 and 2017. Tumors were defined as cystic when preoperative neuroimaging demonstrated cyst formation that was confirmed by intraoperative findings. Solid VS (SVSs) with similar classes were used for comparison. Clinical data of the patients were reviewed retrospectively, including clinical notes and images, as well as operative, pathology, and neuroradiology reports. RESULTS Thirty-two patients (20 males and 12 females) with a mean age of 52.2 years (range 17-77 years) underwent microsurgical resection of 33 CVSs (mean size 3.6 cm, range 1.5-5 cm). Forty-nine patients (26 males and 23 females) with a mean age of 49.9 years (range 21-75 years) underwent microsurgical resection of 49 SVSs (mean size 3 cm, range 2-4.5 cm). All operations were performed via either a retrosigmoid or a translabyrinthine approach. Gross-total resection was achieved in 30 cases in the CVS group (90.9%) and 37 in the SVS group (75.5%). The main reason for subtotal and near-total resection was adherence of the tumor to the brainstem and/or FN in both groups. None of the patients with subtotal or near-total resection in the CVS group demonstrated symptomatic regrowth of the tumor during the mean follow-up period of 41.6 months (range 18-82 months). The FN was anatomically preserved in all patients in both groups. Good FN outcomes were achieved in 15 of CVS (grade I-II; 45.5%) and 35 of SVS (71.4%) surgeries at discharge. Good and fair FN functions were noted in 22 (grade I-II; 81.5%) and 5 (grade III only; 18.5%) of the CVS patients, respectively, at the 1-year follow-up; none of the patients showed poor FN function. CONCLUSIONS Surgery of CVSs does not necessarily result in poor outcomes in terms of the extent of resection and FN function. Special care should be exercised to preserve anatomical continuity of the FN during surgery, since long-term FN function outcomes are much more satisfactory than short-term results. High rates of gross-total resection and good FN outcomes in our study may also suggest that microsurgery stands as the treatment of choice in select cases of large CVSs and SVSs in the era of radiosurgery.

Ventromedial Prefrontal Cortex Damage Is Associated with Decreased Ventral Striatum Volume and Response to Reward.

UNLABELLED: The ventral striatum and ventromedial prefrontal cortex (vmPFC) are two central nodes of the "reward circuit" of the brain. Human neuroimaging studies have demonstrated coincident activation and functional connectivity between these brain regions, and animal studies have demonstrated that the vmPFC modulates ventral striatum activity. However, there have been no comparable data in humans to address whether the vmPFC may be critical for the reward-related response properties of the ventral striatum. In this study, we used fMRI in five neurosurgical patients with focal vmPFC lesions to test the hypothesis that the vmPFC is necessary for enhancing ventral striatum responses to the anticipation of reward. In support of this hypothesis, we found that, compared with age- and gender-matched neurologically healthy subjects, the vmPFC-lesioned patients had reduced ventral striatal activity during the anticipation of reward. Furthermore, we observed that the vmPFC-lesioned patients had decreased volumes of the accumbens subregion of the ventral striatum. Together, these functional and structural neuroimaging data provide novel evidence for a critical role for the vmPFC in contributing to reward-related activity of the ventral striatum. These results offer new insight into the functional and structural interactions between key components of the brain circuitry underlying human affective function and decision-making. SIGNIFICANCE STATEMENT: Maladaptive decision-making is a common problem across multiple mental health disorders. Developing new pathophysiologically based strategies for diagnosis and treatment thus requires a better understanding of the brain circuits responsible for adaptive decision-making and related psychological subprocesses (e.g., reward valuation, anticipation, and motivation). Animal studies provide evidence that these functions are mediated through direct interactions between two key nodes of a posited "reward circuit," the ventral striatum and the ventromedial prefrontal cortex (vmPFC). For the first time in humans, we demonstrate that damage to the vmPFC results in decreased ventral striatum activity during reward anticipation. These data provide unique evidence on the causal mechanisms by which the vmPFC and ventral striatum interact during the anticipation of rewards.

Introduction: surgical management of skull base meningiomas.

Meningiomas represent the most common primary intracranial neoplasm treated by neurosurgeons. Although multimodal treatment of meningiomas includes surgery, radiation-based treatments, and occasionally medical therapy, surgery remains the mainstay of treatment for most symptomatic meningiomas. Because of the intricate relationship of the dura mater and arachnoid mater with the central nervous system and cranial nerves, meningiomas can arise anywhere along the skull base or convexities, and occasionally even within the ventricular system, thereby mandating a catalog of surgical approaches that neurosurgeons may employ to individualize treatment for patients. Skull base meningiomas represent some of the most challenging pathology encountered by neurosurgeons, on account of their depth, invasion, vascularity, texture/consistency, and their relationship to bony anatomy, cranial nerves, and blood vessels. Resection of complex skull base meningiomas often mandates adequate bony removal to achieve sufficient exposure of the tumor and surrounding region, in order to minimize brain retraction and optimally identify, protect, control, and manipulate sensitive neurovascular structures. A variety of traditional skull base approaches has evolved to address complex skull base tumors, of which meningiomas are considered the paragon in terms of both complexity and frequency. In this supplemental video issue of Neurosurgical Focus, contributing authors from around the world provide instructional narratives demonstrating resection of a variety of skull base meningiomas arising from traditionally challenging origins, including the clinoid processes, tuberculum sellae, dorsum sellae, petroclival region, falco-tentorial region, cerebellopontine angle, and foramen magnum. In addition, two cases of extended endoscopic endonasal approaches for tuberculum sellae and dorsum sellae meningiomas are presented, representing the latest evolution in accessing the skull base for selected tumors. Along with key pearls for safe tumor resection, an equally important component of open and endoscopic skull base operations for meningiomas addressed by the contributing authors is the reconstruction aspect, which must be performed meticulously to prevent delayed cerebrospinal fluid leakage and/or infections. This curated assortment of instructional videos represents the authors' optimal treatment paradigms pertaining to the selection of approach, setup, exposure, and principles to guide tumor resection for a wide spectrum of complex meningiomas.

Resection of middle petroclival meningioma via combined anterior transpetrosal and retrosigmoid approaches at two separate stages: 3D operative video.

Surgical access to the petroclival region poses a challenge to neurosurgeons. A wide range of approaches has been demonstrated in the past. In this video, the authors present a 69-year-old male patient who presented with 3-month history of worsening left-sided numbness. The tumor was totally removed in 2 sessions via anterior transpetrosal and retrosigmoid approaches, respectively. The authors demonstrate 2 separate skull base approaches to resect a petroclival meningioma and discuss pitfalls and problems of management for challenging meningiomas. The authors suggest that surgical approaches to petroclival meningiomas should be selected based on an individual case. A skull base team should be versatile in performing all these approaches. The video can be found here: https://youtu.be/BCVrn3TeNvE .

Resection of complex occipital arteriovenous malformation with giant varix: demonstration of microsurgical technique.

The complexity of arteriovenous malformations (AVMs) does not necessarily preclude surgical resection. In this video the authors present a 72-year-old male who was known to have an occipital AVM with a large draining varix for the previous 10 years. The patient had progressively worsening visual and cognitive deficits over several years. Total surgical resection was achieved following single stage preoperative embolization. Although resection of the AVMs is challenging, even in experienced hands, it offers a cure and may improve patient clinical outcome. The video can be found here: https://youtu.be/YI1AwGjJdvo .

Recipient vessel selection in the difficult neck: Outcomes of external carotid artery transposition and end-to-end microvascular anastomosis.

BACKGROUND: Selection of recipient vessels for head and neck microvascular surgery may be limited in the previously dissected or irradiated neck. When distal branches of the external carotid artery (ECA) are unavailable, additional options for arterial inflow are needed. Here we propose high ligation of the ECA and transposition toward the lower neck as an alternative. METHODS: After obtaining institutional approval, patients who underwent head and neck tumor resection and simultaneous free flap reconstruction were identified over a 5-year period. Patients whose recipient artery was listed in the operative report were included. Chart review was performed to identify patient demographics, operative details, and patient and flap complications. In cases where the ECA was used, the artery was traced distally with care taken to protect the hypoglossal nerve. The ECA was then divided and transposed toward the lower neck where an end-to-end microvascular anastomosis was performed. RESULTS: The recipient artery used for head and neck microsurgery was available for 176 flaps, and the facial (n = 127, 72.2%) and external carotid (n = 19, 10.8%) arteries were most commonly used. There were 0 flap thromboses in the ECA group compared to 3 flap thromboses that occurred with other recipient arteries (P = 1.00). No cases of first bite syndrome or hypoglossal nerve injury were identified. CONCLUSIONS: The ECA may be transposed toward the lower neck and used for end-to-end microvascular anastomosis without complication of hypoglossal nerve injury or first bite syndrome. This method may be considered an alternative in patients with limited recipient vessel options for head and neck microsurgery. © 2015 Wiley Periodicals, Inc. Microsurgery 37:96-100, 2017.

Microsurgical resection of tumors of the lateral and third ventricles: operative corridors for difficult-to-reach lesions.

Tumors of the lateral and third ventricles are cradled on all sides by vital vascular and eloquent neural structures. Microsurgical resection, which always requires attentive planning, plays a critical role in the contemporary management of these lesions. This article provides an overview of the open microsurgical approaches to the region highlighting key clinical perspectives.

Supracerebellar transtentorial approach to the tentorial incisura and beyond.

The supracerebellar transtentorial approach via a suboccipital craniotomy provides a corridor to reach lesions of the tentorial incisura and supratentorial lesions of the posterior medial basal temporal lobe, such as lesions of the posterior parahippocampal and fusiform gyri. The supracerebellar transtentorial approach obviates the need for either retraction of eloquent cortex or a transcortical route to reach lesions in this region. We present three cases that demonstrate the utility of this approach: a left-sided tentorial meningioma with superior projection, a left-sided posterior parahippocampal cavernous malformation, and a left-sided posterior parahippocampal grade 2 oligodendroglioma. The video can be found here: https://youtu.be/OLnzUGZfUqk .