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Objective: This study describes an innovative optic nerve MRI protocol for better delineating optic nerve anatomy from neighboring pathology., Methods: Twenty-two patients undergoing MRI examination of the optic nerve with the dedicated protocol were identified and included for analysis of imaging, surgical strategy, and outcomes. T2-weighted and fat-suppressed T1-weighted gadolinium-enhanced images were acquired perpendicular and parallel to the long axis of the optic nerve to achieve en face and in-line views along the course of the nerve., Results: Dedicated optic nerve MRI sequences provided enhanced visualization of the nerve, CSF within the nerve sheath, and local pathology. Optic nerve sequences leveraged the "CSF ring" within the optic nerve sheath to create contrast between pathology and normal tissue, highlighting areas of compression. Tumor was readily tracked along the longitudinal axis of the nerve by images obtained parallel to the nerve. The findings augmented treatment planning., Conclusions: The authors present a dedicated optic nerve MRI protocol that is simple to use and affords improved cross-sectional and longitudinal visualization of the nerve, surrounding CSF, and pathology. This improved visualization enhances radiological evaluation and treatment planning for optic nerve lesions.

Falcotentorial meningiomas involve the tentorial apex and straight sinus, posing challenges when encasing the galenic venous system. 1 Microneurosurgery is considered the best treatment option for large falcotentorial meningiomas because it provides a definitive cure. 2 In contrast, Gamma Knife surgery mainly allows the control of smaller or residual tumors after microsurgical resection. 3 Approach selection between interhemispheric supratentorial versa supracerebellar transtentorial is dictated by the displacement of the Galen vein. 1 , 4-8 Video 1 describes the critical surgical steps of the supracerebellar "flyover" approach for a Bassiouni type II dumbbell falcotentorial meningiomas encasing the galenic venous system. Preoperative embolization was ruled out due to potential additional morbidity and mortality risks. 9 , 10 A perimedian supracerebellar infratentorial transtentorial approach was performed with the patient in ¾ prone Concorde position. After early devascularization and division of the tentorium, the meningioma was internally debulked while preserving the arachnoid plane. The posterior choroidal arteries, internal cerebral veins, basal veins of Rosenthal, and vein of Galen were carefully dissected, and the tumor was completely resected. The patient was discharged on postoperative day 3 with no deficits. Postoperative magnetic resonance imaging confirmed a Simpson grade 1 resection. Pathology revealed a grade 2 meningioma. The patient remained asymptomatic with no recurrence at a 10-year follow-up. The reported case demonstrates that the most critical factor in the choice of approach to midline dumbbell falcotentorial meningiomas is the relationship of the tumor to the galenic venous system and its tributaries., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: The objective was to assess the performance of a context-enriched large language model (LLM) compared with international neurosurgical experts on questions related to the management of vestibular schwannoma. Furthermore, another objective was to develop a chat-based platform incorporating in-text citations, references, and memory to enable accurate, relevant, and reliable information in real time., Methods: The analysis involved 1) creating a data set through web scraping, 2) developing a chat-based platform called neuroGPT-X, 3) enlisting 8 expert neurosurgeons across international centers to independently create questions (n = 1) and to answer (n = 4) and evaluate responses (n = 3) while blinded, and 4) analyzing the evaluation results on the management of vestibular schwannoma. In the blinded phase, all answers were assessed for accuracy, coherence, relevance, thoroughness, speed, and overall rating. All experts were unblinded and provided their thoughts on the utility and limitations of the tool. In the unblinded phase, all neurosurgeons provided answers to a Likert scale survey and long-answer questions regarding the clinical utility, likelihood of use, and limitations of the tool. The tool was then evaluated on the basis of a set of 103 consensus statements on vestibular schwannoma care from the 8th Quadrennial International Conference on Vestibular Schwannoma., Results: Responses from the naive and context-enriched Generative Pretrained Transformer (GPT) models were consistently rated not significantly different in terms of accuracy, coherence, relevance, thoroughness, and overall performance, and they were often rated significantly higher than expert responses. Both the naive and content-enriched GPT models provided faster responses to the standardized question set than expert neurosurgeon respondents (p < 0.01). The context-enriched GPT model agreed with 98 of the 103 (95%) consensus statements. Of interest, all expert surgeons expressed concerns about the reliability of GPT in accurately addressing the nuances and controversies surrounding the management of vestibular schwannoma. Furthermore, the authors developed neuroGPT-X, a chat-based platform designed to provide point-of-care clinical support and mitigate the limitations of human memory. neuroGPT-X incorporates features such as in-text citations and references to enable accurate, relevant, and reliable information in real time., Conclusions: The present study, with its subspecialist-level performance in generating written responses to complex neurosurgical problems for which evidence-based consensus for management is lacking, suggests that context-enriched LLMs show promise as a point-of-care medical resource. The authors anticipate that this work will be a springboard for expansion into more medical specialties, incorporating evidence-based clinical information and developing expert-level dialogue surrounding LLMs in healthcare.

Background: Meckel cave tumors are relatively rare, especially trigeminal nerve (TN) schwannomas. These tumors frequently project through the trigeminal pore, occupying the middle and posterior fossae. The most used routes to this region are the suboccipital retrosigmoid intradural approach (SORSA) and the transzygomatic middle fossa approach (TZMFA). Both approaches allow further exposure by adding intraoperative techniques, such as removing the suprameatal tubercle (retrosigmoid intradural suprameatal approach [RISA]) and the petrous apex (TZMFA-PA), respectively. This study aims to understand how TN exposure differs between both surgical approaches and how it increases by adding specific surgical maneuvers to these techniques., Methods: Five formalin-fixed adult cadaver heads were submitted to high-resolution computed tomography and their images were loaded into the neuronavigation device. Anatomic key points were defined along the outline of the TN, and their three-dimensional spatial locations were collected following each surgical approach. This process allowed the calculation of the TN exposed area obtained through each technique., Results: The mean areas of exposure of the TN were 125.9 mm 2 with SORSA and 208.9 mm 2 with RISA, which represents an additional mean gain of 61.92% (P = 0.047). Using TZMFA, a mean exposure of 419.24 mm 2 was obtained. When TZMFA-PA was used, the mean exposed area was 486.03 mm 2 , representing a mean gain in the exposure area of 16.81% (P = 0.072)., Conclusions: Our study suggests that TZMFA allows better exposure of TN ganglionic and postganglionic segments, and the removal of the PA adds the preganglionic segment visualization, although with less TN exposed area compared with RISA. With SORSA, the additional suprameatal tubercle removal shows the trigeminal pore and the medial margin of the central portion of the TN ganglionic segment, making it possible to expose the mouth of the Meckel cave and part of its contents., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Geniculate ganglion hemangioma (GGH) is rarely presented in the neurosurgical literature. It extends extradurally on the middle fossa floor and displaces the intratemporal part of the facial nerve. Surgical treatment is advisable at early symptoms. Proposed techniques include fascicular-sparing resection or nerve interruption with grafting. No definitive conclusions exist about the superiority of a certain technique in preserving facial nerve integrity and function. Through the description of a surgically managed symptomatic GGH, we herein discuss literature data about the surgical results of fascicular-sparing resection versus grafting. A PRISMA-based literature search was performed on the PubMed database. Only articles in English and published since 1990 were selected and furtherly filtered based on the best relevance. Statistical comparisons were performed with ANOVA. One hundred sixteen GGHs were collected, 56 were treated by fascicular-sparing resection, and 60 were treated by grafting. The facial function was improved, or unchanged, in 53 patients of the fascicular-sparing group and 30 patients of the grafting one. Sixty-five patients achieved a good (House-Brackmann (HB) grade III) postoperative facial outcome, of which 47 and 18 belonged to the fascicular-sparing and grafting group, respectively. Greater efficacy of the fascicular-sparing technique in the achievement of a better facial outcome was found (p = 0.0014; p = 0.0022). A surgical resection at the earliest symptoms is critical to preserve the facial nerve function in GGHs. Fascicular-sparing resection should be pursued in symptomatic cases with residual facial function (I-III HB). Conversely, grafting has a rationale for higher HB grades (V-VI). Broader studies are required to confirm these findings and turn them into new therapeutic perspectives., (© 2023. The Author(s).)

Surgery of cerebellopontine angle (CPA) facial nerve schwannoma (FNS) in patients with good facial nerve function is a challenge. 1-10 Video 1 highlights the fascicular-sparing technique for resection of a CPA FNS. A 41-year-old male patient symptomatic with persistent headaches and tinnitus underwent a retrosigmoid approach for a right cystic CPA tumor, presumed vestibular schwannoma. Intraoperatively, the facial nerve was identified as fine multiple strands splayed around the perimetry of the tumor, which elicited a motor response at a low threshold stimulation. This finding led to the intraoperative diagnosis of FNS according to the reported criteria. 5 Neuromonitoring-assisted fascicular-sparing resection technique was performed. It involved the gradual separation of the uninvolved nerve fibers using a fine-stimulating dissector at a threshold of 0.2 mA. Entry into the tumor was at a stimulation silent cyst. The tumor was debulked with preservation of the endoneurium and pulse irrigation hemostasis. A near-total resection was performed. The patient was discharged on the second postoperative day with a House-Brackman III facial nerve deficit. The deficit remained stable during the following annual follow-up visits. Resection of CPA FNS is indicated at the earliest sign of deficit. However, it might be encountered as masquerading at the surgery of an acoustic tumor. The fascicular-sparing technique is critical in avoiding injuries to the endoneurium during the resection and with the ability to preserve function. The sparing of endoneurium avoids collagenization, fibrosis, and ischemia of the nerve, which are known to be the pathologic substrate of worse functional outcomes., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The evolution of endoscopic trans-sphenoidal surgery raises the question of the role of transcranial surgery for pituitary tumors, particularly with the effectiveness of adjunct irradiation. This narrative review aims to redefine the current indications for the transcranial approaches for giant pituitary adenomas in the endoscopic era. A critical appraisal of the personal series of the senior author (O.A.-M.) was performed to characterize the patient factors and the tumor's pathological anatomy features that endorse a cranial approach. Traditional indications for transcranial approaches include the absent pneumatization of the sphenoid sinus; kissing/ectatic internal carotid arteries; reduced dimensions of the sella; lateral invasion of the cavernous sinus lateral to the carotid artery; dumbbell-shaped tumors caused by severe diaphragm constriction; fibrous/calcified tumor consistency; wide supra-, para-, and retrosellar extension; arterial encasement; brain invasion; coexisting cerebral aneurysms; and separate coexisting pathologies of the sphenoid sinus, especially infections. Residual/recurrent tumors and postoperative pituitary apoplexy after trans-sphenoidal surgery require individualized considerations. Transcranial approaches still have a critical role in giant and complex pituitary adenomas with wide intracranial extension, brain parenchymal involvement, and the encasement of neurovascular structures.

Objective: Facial nerve (FN) schwannomas are extremely rare. According to their origin and involved segment(s), they constitute distinct subtypes. Intact FN function presents a management challenge, particularly in the cerebellopontine angle cisternal subtype that masquerades as a vestibular schwannoma. Fascicular-sparing technique with subtotal resection can maintain a good FN function. This study focuses on management to maintain good FN function., Methods: A retrospective analysis of a cohort of 13 patients harboring FN schwannoma. Patient demographics, clinical findings, imaging, surgical intervention, and outcomes were analyzed., Results: Five women and 8 men, with an average age of 55.3 years (39-75 years), harbored 6 cisternal, 2 ganglion, and 5 combined tumors. Average tumor size was 28.3 mm (16-50 mm). Eleven patients underwent surgery. Seven patients had fascicle-sparing technique, 5 of whom maintained their preoperative FN function, whereas 2 patients with near-total removal had a deterioration in FN function. Two patients with preoperative complete facial paralysis had gross total removal with interposition nerve graft., Conclusions: FN schwannomas management is individualized according to the subtype and the FN function at presentation. When FN function is normal, observation can be applied for prolonged period of time. At the early sign of deterioration, sub- or near-total resection with fascicle sparing technique can be performed. The cisternal subtype masquerade as vestibular schwannoma and should be recognized at the initial exposure by the appearance of finely splayed nerve fascicles at the perimetry of the tumor which elicits a motor response at low threshold stimulation., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Venous thromboembolism (VTE), encompassing deep venous thrombosis (DVT) and pulmonary embolism (PE), causes postoperative morbidity and mortality in neurosurgical patients. The use of pharmacological prophylaxis for DVT prevention in the immediate postoperative period carries increased risk of intracranial hemorrhage, especially after skull base surgeries., Objective: To investigate the impact of routine Doppler ultrasound monitoring in prevention and tiered management of VTE after skull base surgery., Methods: We retrospectively analyzed a large cohort of consecutive adult patients who were prospectively and uniformly managed with routine monitoring by Doppler ultrasound for DVT after resection of a skull base tumor., Results: A total of 389 patients who underwent 459 surgeries for intracranial tumor resection were analyzed. Skull base meningioma was the most common pathology. Forty-four (9.59%) postoperative VTEs were detected: 9 (1.96%) with PE with or without DVT and 35 (7.63%) with DVT alone. Four cases of subsegmental PE were diagnosed without evidence of lower extremity DVT, possibly in the setting of peripherally inserted central catheters maintenance. One patient had a preoperative proximal DVT and underwent a prophylactic inferior vena cava filter but expired from PE after discharge. Prior history of VTE (risk ratio [RR] 5.13; 95% CI 2.76-7.18; P < .01), anesthesia duration (RR 1.14; 95% CI 1.03-1.27; P = .02), and blood transfusion (RR 1.95; 95% CI 1.01-3.37; P = .04) were associated with VTE development on multivariate analysis., Conclusion: Routine postoperative venous ultrasound monitoring detects asymptomatic DVT guiding management. This is an alternative strategy to prescribing pharmacological VTE prophylaxis immediately after lengthy surgeries for intracranial tumors. Peripherally inserted central catheters were associated with subsegmental PE., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Syringomyelia is often resistant to various treatment modalities. 1 Chiari I malformations are associated with syringomyelia in approximately 69% of operative cases. 2 Failure to resolve syringomyelia after Chiari decompression is common. 3 The pathophysiology of Chiari-associated syringomyelia has been well studied, with Oldfield emphasizing the water-hammer mechanism, with treatment limited to bony decompression and duraplasty. 4 On the other hand, capacious fourth ventricular drainage is thought to be essential for syrinx resolution. Persistence or progression of the syrinx after decompression is an indication for reoperation. Direct shunting of the syrinx is associated with high failure rates. 1 , 5-7 The technique of shunting the fourth ventricle has been applied successfully in the pediatric population. 3 , 8-10 We emphasize the need to ensure outflow from the fourth ventricle in Chiari decompressions associated with syringomyelia. In revisions to treat progressive syringomyelia after failed decompression, we undertake the following steps: 1) adequate lateral bony decompression, 11-13 2) lysis of scar/adhesions around the cisterna magna, 3) opening the fourth ventricle outlet by releasing any web/adhesions, 4) insertion of a shunt from the fourth ventricle to the cervical subarachnoid space, and 5) bipolar coagulation of the lateral tonsillar pia to maintain patency of cerebrospinal fluid pathways. 8 We favor autologous fascia or pericranium for expansile duraplasty, as the use of nonautologous materials may cause excessive scarring. 14-16 In this video, we demonstrate these tenets in 3 cases of Chiari-associated syringomyelia, 2 revisions and 1 primary case, with excellent resolution of the syrinx (Video 1). The patients consented to surgery and publication of images., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Meningiomas are the most common primary intracranial tumor in adults. Clinical care is currently guided by the World Health Organization (WHO) grade assigned to meningiomas, a 3-tiered grading system based on histopathology features, as well as extent of surgical resection. Clinical behavior, however, often fails to conform to the WHO grade. Additional prognostic information is needed to optimize patient management., Methods: We evaluated whether chromosomal copy-number data improved prediction of time-to-recurrence for patients with meningioma who were treated with surgery, relative to the WHO schema. The models were developed using Cox proportional hazards, random survival forest, and gradient boosting in a discovery cohort of 527 meningioma patients and validated in 2 independent cohorts of 172 meningioma patients characterized by orthogonal genomic platforms., Results: We developed a 3-tiered grading scheme (Integrated Grades 1-3), which incorporated mitotic count and loss of chromosome 1p, 3p, 4, 6, 10, 14q, 18, 19, or CDKN2A. 32% of meningiomas reclassified to either a lower-risk or higher-risk Integrated Grade compared to their assigned WHO grade. The Integrated Grade more accurately identified meningioma patients at risk for recurrence, relative to the WHO grade, as determined by time-dependent area under the curve, average precision, and the Brier score., Conclusion: We propose a molecularly integrated grading scheme for meningiomas that significantly improves upon the current WHO grading system in prediction of progression-free survival. This framework can be broadly adopted by clinicians with relative ease using widely available genomic technologies and presents an advance in the care of meningioma patients., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Neuro-Oncology.)

Background: Posterior fossa AVMs constitute about 10% of AVMs and are associated with a higher rate of hemorrhage and increased morbidity and mortality rates necessitating treatment with rare exception. Cerebellar AVMs differ markedly from their supratentorial counterparts in that there are no perforating vessels involvement, drainage into the deep cerebral venous system, or presence of eloquent functional area except for the dentate nucleus. While Yaşargil has classified cerebellar AVMs into seven subtypes according to their location, de Oliveira et al . have classified them using a more impactful grading system based on the size, location, and involvement of the dentate nucleus with the highest risk being III (size over 4 cm) C (mixed superficial and deep location) * (dentate involvement). In this extensive AVM with multiple arterial feeders from the SCA, AICA, and PICAs, preoperative embolization facilitates the safe surgical removal., Case Description: We present the case of resection of de Oliveira et al . IIIC* cerebellar AVM highlighting the tenets of preoperative embolization, wide surgical exposure with an extended retrosigmoid approach, arachnoidal dissection of the SAC, AICA, and PICA feeders, parenchymal dissection with preservation of the dentate nucleus, and preservation of venous drainage until complete disconnection. The patient consented to surgery after presenting with hemorrhage and developed hydrocephalus and CSF leak, managed successfully., Conclusion: de Oliveira et al . classification is highly impactful in grading posterior fossa AVMs., Competing Interests: There are no conflicts of interest., (Copyright: © 2022 Surgical Neurology International.)

Given the difficulty and importance of achieving maximal resection in chordomas and chondrosarcomas, all available tools offered by modern neurosurgery are to be deployed for planning and resection of these complex lesions. As demonstrated by the review of our series of skull base chordoma and chondrosarcoma resections in the Advanced Multimodality Image-Guided Operating (AMIGO) suite, as well as by the recently published literature, we describe the use of advanced multimodality intraoperative imaging and neuronavigation as pivotal to successful radical resection of these skull base lesions while preventing and managing eventual complications.

Background: Programmed death ligand 1 (PD-L1) contributes to tumor immunosuppression and is upregulated in aggressive meningiomas. We performed a phase II study of nivolumab, a programmed death 1 (PD-1) blocking antibody among patients with grade ≥2 meningioma that recurred after surgery and radiation therapy., Methods: Twenty-five patients received nivolumab (240 mg biweekly) until progression, voluntary withdrawal, unacceptable toxicity, or death. Tumor mutational burden (TMB) and quantification of tumor-infiltrating lymphocytes (TIL) were evaluated as potential immunocorrelative biomarkers. Change in neurologic function was prospectively assessed using the Neurologic Assessment in Neuro-Oncology (NANO) scale., Results: Enrolled patients had multiple recurrences including ≥3 prior surgeries and ≥2 prior courses of radiation in 60% and 72%, respectively. Nivolumab was well tolerated with no unexpected adverse events. Six-month progression-free survival (PFS-6) rate was 42.4% (95% CI: 22.8, 60.7) and the median OS was 30.9 months (95% CI: 17.6, NA). One patient achieved radiographic response (ongoing at 4.5 years). TMB was >10/Mb in 2 of 15 profiled tumors (13.3%). Baseline TIL density was low but increased posttreatment in 3 patients including both patients with elevated TMB. Most patients who achieved PFS-6 maintained neurologic function prior to progression as assessed by NANO., Conclusion: Nivolumab was well tolerated but failed to improve PFS-6, although a subset of patients appeared to derive benefit. Low levels of TMB and TIL density were typically observed. NANO assessment of neurologic function contributed to outcome assessment. Future studies may consider rationally designed combinatorial regimens., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Chordoma is a rare skull base tumor with malignant behavior.1-3 It invades locally with high recurrences, metastasizes distally, and seeds after interventions.1-4 Chordoma exemplifies the malignant progression doctrine as it accumulated genetic mutations. The natural history of untreated disease is 2.4 yr on average survival.5 Best tumor control is achieved by radical resection, followed by high doses radiation. Multicentric chordoma is an ill-defined challenging entity extremely rare in the literature. However, chordoma is known for distal metastasis, particularly to the lungs, iatrogenic cerebrospinal fluid (CSF) dissemination with drop metastasis, or surgical implantation. A subset of patients present with synchronous or metachronous regional or distal neuraxial lesions associated with the initial chordoma. Patients presenting with multicentric bony axial lesions and no extra-axial metastases point toward the multicentric chordoma concept rather than local, hematogenous, or CSF spread.6-12 Biopsy of these multicentric lesions can show a spectrum of abnormalities ranging from benign notochordal tumor to chordomas confirming the multicentric hypothesis.9 We present a patient who underwent a bilateral transcondylar approach for giant craniovertebral junction chordoma and then treated with radiation and a second lesion at the C6 transverse foramen. Six years later, she presented with a chordoma at the petrous apex. The patient consented to surgery and to the publications of her image. The participants and any identifiable individuals consented to publication of his/her image. Image at 1:39 reprinted with permission from Al-Mefty O, Operative Atlas of Meningiomas. Vol 1, © LWW, 1998., (Copyright © Congress of Neurological Surgeons 2021. All rights reserved.)

Owing to their invasive character, extreme vascularity, and critical location, glomus jugulare tumors present a formidable challenge. Techniques have been developed for safe and successful removal of even giant glomus paragangliomas.1-3 Preoperative evaluation including genetic, hormonal, and multiplicity workup4 has enhanced the safety of surgical management, as did modern preoperative embolization by eliminating excessive blood loss.5 Despite these advancements, surgical outcomes of glomus jugulare remain haunted by cranial nerve dysfunction such as facial nerve palsies and hearing loss, with lower cranial nerves dysfunction being the most morbid. These can be avoided by technical maneuvers to preserve the cranial nerves. The external ear canal is not closed to maintain conductive hearing. The facial nerve is not transpositioned and kept inside a bony protective canal. Cranial nerves IX, X, and XI are the most vulnerable because they pass through the jugular foramen ventral to the venous bulb wall. They are preserved by intrabulbar dissection that maintains a protective segment of the venous wall over the nerves. By mastering the anatomy of the upper neck, meticulous dissection is performed to preserve the course of IX, X, XI, and XII.6,7 Ligation of the jugular vein is delayed until the tumor is totally isolated to avoid diffuse bleeding.7 We present the case of a 60-yr-old woman with a glomus jugulare tumor with intradural, extradural, and cervical extension. The technical nuances of cranial nerves preservation are demonstrated. The patient consented to the procedure and publication of her images. Images at 2:12, 2:50, and 3:09 from Al-Mefty and Teixeira,6 with permission from JNSPG., (Copyright © Congress of Neurological Surgeons 2021. All rights reserved.)

Giants of neurosurgery have made contributions that might at times seem to be minor maneuvers but have a major impact on safe surgery, such as Sugita and Kobayashi's description of the preservation of the bridging sagittal veins.1 The interhemispheric approach is haunted by risk to the bridging veins and resultant venous infarction. At the midsegment, this could produce devastating neurological deficits.2 This is an especially critical factor in falcine meningiomas in which the location of the tumor narrows the options for the surgical corridor, particularly if an additional falcine margin, "Grade Zero" resection, is to be performed.3 Detailed preoperative neuroimaging workup is required to plan the appropriate surgical strategy and minimize risk for venous complications. This may include magnetic resonance or computed tomography venogram, dynamic computed tomography angiography,4 or in some cases formal angiography to assess the relationship with the superior sagittal sinus, the anatomy of parasagittal bridging veins in relation to the lesion, and the patterns of collateral venous drainage. While bridging veins may be displaced, compressed, or obscured by tumor involvement,5 microsurgical technique can facilitate the safe identification and preservation of this crucial anatomy. Bridging veins are separated from the underlying cortex to a distance from the sinus, allowing for improved relaxation of the ipsilateral cortex, without venous compromise.1,6 Herein, we demonstrate a case of a large falcine meningioma with a "Grade Zero" resection, with mobilization of the parasagittal bridging veins to develop the interhemispheric surgical corridor. The patient consented for surgery., (Copyright © Congress of Neurological Surgeons 2021. All rights reserved.)

Meningiomas are a common pineal region tumor in adults.1 They frequently reach large size with pending serious neurological consequences.1 Although they are more common in women, their presence in men might raise concerns about a higher-grade meningioma. Accordingly, their treatment starts with surgical resection. Their origin is the falcotentorial junction involving the midbrain tectum and the vital deep venous system. The torcular, transverse sinuses, cerebellar veins, straight sinus, internal occipital veins, basal veins, and internal cerebral veins are encountered requiring a cautious fine intra-arachnoidal dissection under high magnification.2 Multiple surgical approaches are described for pineal area tumors with the advantages and disadvantages of each guiding the selection of the approach.3 We believe that the main deciding factor is the relationship of the vein of Galen and its tributaries to the tumor, simply choosing the route that encounters the tumor first and the vein last. We demonstrate the surgical nuances of removing a pineal area meningioma that displaced the vein of Galen superiorly, prompting the resection through a lateral infratentorial supracerebellar approach. We currently prefer the 3/4 concord position because it provides a superb direct exposure over one cerebellar hemisphere, with the cerebellum relaxed downward while the bridging veins are not severely stretched with gravity.4 The sitting surgeon with resting arms in an ergonomic position is able to perform fine microsurgical dissection over extended time.5 The patient was a 57-year-old man with a large falcotentorial meningioma. The patient consented to the surgery and publication of his images., (Copyright © Congress of Neurological Surgeons 2021. All rights reserved.)

Syringomyelia with compression at the foramen magnum is a well-studied subject with a pathophysiological hypothesis explaining syrinx development and treatment.1,2 However, compression of the cervical cord, as in cervical spondylosis, can also lead to cavitation in the spinal cord.3,4 Although the association of intramedullary spinal cord tumors with syringomyelia is well known,5 the association of extramedullary tumors with syringomyelia is scarcely reported, and it is of unknown mechanism and uncertain outcomes regarding syrinx resolution. Syringomyelia is reported to be associated with intramedullary spinal schwannoma.6 However, spinal schwannomas are by and large extramedullary tumors that produce deficits through compressive radiculopathy or myelopathy. The association of extramedullary schwannomas with syringomyelia is extremely rare. In this article, we present a patient with an extramedullary high-cervical schwannoma causing significant syringomyelia who underwent microsurgical resection of the schwannoma, with subsequent total resolution of the syringomyelia. The patient consented for surgery. Images from Lancet 1969 at 6:36 in video Reprinted from The Lancet, Vol. 294, Bernard Williams, The Distending Force in the Production of "Communicating Syringomyelia," Pages 189-193, Copyright 1969, with permission from Elsevier., (Copyright © Congress of Neurological Surgeons 2021. All rights reserved.)