Details of a Researcher - Toda, Masahiro

Papers - Toda, Masahiro

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Analysis of temporobasal vein with short subdural segment for anterior transpetrosal approach

Tamura R, Toda M, Morimoto Y, Sato M, Akiyama T, Yoshida K

World Neurosurg （World Neurosurgery) 132 e554 - e562 2019

Research paper (scientific journal), Joint Work, ISSN 18788750

Background: The anterior transpetrosal approach (ATPA) is applied to petroclival and brainstem lesions. Although neurosurgeons need to minimize the risk of neurologic complications, brain retraction is necessary for procedures of ATPA. Bridging veins (BVs) limit mobility of the temporal lobe. In the present study, BVs around the petrous bone were analyzed, focusing on the dural entrance and termination points. Methods: The relationship between subdural and meningeal segments of temporobasal veins (TBVs) was analyzed by preoperative computed tomography venography in 102 patients who underwent ATPA. TBVs were classified by the dural entrance and termination points. Results: TBVs mainly entered the transverse sinus and rarely entered transverse-sigmoid sinus (T-S) junction and superior petrosal sinus (SPS). TBVs entered a dural sinus either directly or indirectly through a meningeal vein. The changes in vascular diameter of the lumen, shape, and course were identified between the subdural and meningeal segments. Generally, BVs with long subdural segment do not limit mobility of the temporal lobe. TBVs draining into the T-S junction and SPS tended to be shorter than those draining into the transverse sinus. Furthermore, a few TBVs indirectly entered the dural sinuses through the meningeal vein (early dural entrance). The subdural segment of these TBVs was much shorter. Conclusions: TBVs entering the T-S junction or SPS with short subdural segment may limit the mobility of the temporal lobe. Changes in vascular diameter, shape, and course were detected by computed tomography venography, which was helpful to detect the subdural-meningeal transition.

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Identification of KLRC2 as a candidate marker for brain tumor-initiating cells

Ishihara E, Takahashi S, Fukaya R, Ohta S, Yoshida K, Toda M

Neurol Res （Neurological Research) 41 （ 11 ） 1043 - 1049 2019

Research paper (scientific journal), Joint Work, ISSN 01616412

Objective: Brain tumor-initiating cells are characterized by their features of self-renewal, multi-lineage differentiation, and tumorigenicity. We analyzed the gene expression of brain tumor-initiating cells to identify their novel cellular markers. Methods: We performed cDNA microarray, in silico expressed sequence tags (ESTs), RT-PCR, and q-PCR analyses. Results: We identified 10 genes that were more highly expressed in brain tumor-initiating cells than in neural stem cells. In addition, we identified 10 other genes that were more highly expressed in brain tumor-initiating cells than in glioma cell line cells from the cDNA microarray analysis. Using the EST database, we looked to see if the 20 genes were expressed more highly in gliomas, compared with normal adult brains. Among the 20 genes, five (KLRC2, HOXB2, KCNJ2, KLRC1, and COL20A1) were expressed more than twice in glioma samples, compared with normal adult brains, and, therefore, were referred for further evaluation. RT-PCR was conducted using cDNA samples obtained from neural stem cells, normal brain tissue, fetal brain tissue, glioma cell lines, and glioma tumor-initiating cell lines. KLRC2, a transmembrane activating receptor in natural killer cells, was expressed more highly in glioma-initiating cells than in neural stem cell lines or normal adult brain tissue. The q-PCR analysis revealed that expression of KLRC2 was significantly higher in brain tumor-initiating cells compared to normal brain controls. Conclusion: KLRC2 could be a novel cellular marker for brain tumor-initiating cells.

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Early prediction of clinical outcomes in patients with aneurysmal subarachnoid hemorrhage using computed tomography texture analysis

Kanazawa T, Takahashi S, Minami Y, Jinzaki M, Toda M, Yoshida K

J Clin Neurosci （Journal of Clinical Neuroscience) 71 144 - 149 2019

Research paper (scientific journal), Joint Work, ISSN 09675868

Radiological evaluation of subarachnoid hemorrhage (SAH) is often subject to interobserver variability. The aim of this study was to retrospectively detect computed tomography (CT) texture parameters in the early postictal state to predict cerebral vasospasm, delayed cerebral ischemia (DCI), and functional outcome in aneurysmal SAH using quantitative CT texture analysis (CTTA) via a commercially available software program and routine CT images. 40 patients with aneurysmal SAH surgically treated at the Keio University Hospital during a four-year period were analyzed. CT texture analyses were performed using a commercially available software program (Synapse Vincent). The following texture parameters of blood clots in the subarachnoid space and cerebral edema were assessed: mean CT value, entropy, skewness, and kurtosis. The mean CT value of blood clots in the subarachnoid space was significantly associated with cerebral vasospasm, DCI, and functional outcome. The mean CT value ≥ 49.64 Hounsfield units (HU) predicted cerebral vasospasm with a sensitivity and specificity of 85.7% and 61.5%, respectively (area under the curve [AUC] = 0.758). The mean CT value ≥ 49.95 HU predicted DCI with a sensitivity and specificity of 100% and 60.6%, respectively (AUC = 0.810). The mean CT value ≥ 53.00 HU predicted poor functional outcome with a sensitivity and specificity of 56.3% and 91.7%, respectively (AUC = 0.747). CTTA using a commercially available software program demonstrated that the mean CT value of clots in the subarachnoid space in the early postictal state could predict vasospasm, DCI, and clinical outcome with a high sensitivity and specificity.

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A VEGF receptor vaccine demonstrates preliminary efficacy in Neurofibromatosis type 2.

Tamura R, Fujioka M, Morimoto Y, Ohara K, Kosugi K, Oishi Y, Sato M, Ueda R, Fujiwara H, Hikichi T, Noji S, Oishi N, Ogawa K, Kawakami Y, Ohira T, Yoshida K, Toda M

Nature Commun （Nature Communications) 10 （ 1 ） 5758 2019

Research paper (scientific journal), Joint Work

The anti-VEGF antibody bevacizumab has shown efficacy for the treatment of neurofibromatosis type 2 (NF2). Theoretically, vascular endothelial growth factor receptors (VEGFRs)-specific cytotoxic T lymphocytes (CTLs) can kill both tumor vessel cells and tumor cells expressing VEGFRs. Here we show an exploratory clinical study of VEGFRs peptide vaccine in seven patients with progressive NF2-derived schwannomas. Hearing improves in 2/5 assessable patients (40%) as determined by international guidelines, with increases in word recognition scores. Tumor volume reductions of ≥20% are observed in two patients, including one in which bevacizumab had not been effective. There are no severe adverse events related to the vaccine. Both VEGFR1-specific and VEGFR2-specific CTLs are induced in six patients. Surgery is performed after vaccination in two patients, and significant reductions in the expression of VEGFRs in schwannomas are observed. Therefore, this clinical immunotherapy study demonstrates the safety and preliminary efficacy of VEGFRs peptide vaccination in patients with NF2.

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Relationship between pneumatization of lateral recess in the sphenoid sinus and removal of cavernous sinus invasion in pituitary adenomas by endoscopic endonasal surgery.

Kosugi K, Tamura R, Mase T, Tamura H, Jinzaki M, Yoshida K, Toda M

Surg Neurol Int 10 222 2019

Research paper (scientific journal), Joint Work

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Surgical management of trigeminal schwannomas: Preservation of the trigeminal nerve

Toda M., Tamura R., Yoshida K.

Japanese Journal of Neurosurgery （Japanese Journal of Neurosurgery) 28 （ 7 ） 407 - 413 2019

ISSN 0917950X

Trigeminal schwannomas can develop anywhere along the course of the trigeminal root, ganglion, and nerve branches. The most frequent tumor site is Meckel’s cave. The tumor, is dumbbell in shape, often extends to the posterior cranial fossa. A series of surgical approaches, which primarily include skull base extradural approaches, used for the management of trigeminal schwannomas has been discussed based on tumor site. More recently, an endoscopic endonasal approach has been used for lesions in Meckel’s cave, pterygoid palatine fossa, and infratemporal fossa. This article describes anatomy‒based surgical approaches for the management of trigeminal schwannoma and surgical approaches aimed at functional preservation.

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Endoscopic endonasal approach combined with a simultaneous transcranial approach for giant pituitary tumors.

Kuga D, Toda M, Ozawa H, Ogawa K, Yoshida K

World Neurosurg 121 173 - 179 2019

Research paper (scientific journal), Joint Work, Accepted

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In Reply to the Letter to the Editor Regarding “Treatment Strategy for Tuberculum Sellae Meningiomas Based on Preoperative Radiologic Assessment”

114 Kuga D, Toda M, Yoshida K.

World neurosurg 125 （ 1 ） 2019

Research paper (scientific journal), Joint Work

Difference in Immunosuppressive Cells Between Peritumoral Area and Tumor Core in Glioblastoma

Tamura R., Ohara K., Sasaki H., Morimoto Y., Kosugi K., Yoshida K., Toda M.

World Neurosurgery （World Neurosurgery) 120 e601 - e610 2018.12

ISSN 18788750

Background: Vascular endothelial growth factor (VEGF)-A and VEGF receptor expression in the peritumoral brain zone (PBZ) differs from that in the tumor core (TC) of glioblastoma. To date, no comparative study has investigated the expression of immunosuppressive cells in the PBZ and TC of glioblastoma. Methods: In 10 patients with newly diagnosed glioblastoma, we used immunohistochemistry to analyze the expression of VEGF-A, hypoxia-inducible factor-1α, programmed cell death-1 (PD-1), Foxp3, CD163, CD4, and CD8 to assess the immunosuppressive microenvironment. Results: The number of Foxp3 and CD163 cells was significantly greater in the TC than in the PBZ and correlated with greater expression of hypoxia-inducible factor-1α and VEGF-A in the TC than in the PBZ. The number of CD8 T cells was lower in the TC than in the PBZ, and the TC had more PD-1 CD8 T cells compared with the PBZ. These results suggest that the hypoxic condition could be associated with PD-1 expression on lymphocytes, the distribution of Foxp3 regulatory T cells and CD163 tumor-associated macrophages. Conclusions: The present study reports the first clinicopathologic features of the differences in immunosuppressive cells and the expression of immune checkpoint molecules between the TC and PBZ of glioblastoma. + + + + + + +

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Pros and cons of using ORBEYE™ for microneurosurgery

Takahashi S., Toda M., Nishimoto M., Ishihara E., Miwa T., Akiyama T., Horiguchi T., Sasaki H., Yoshida K.

Clinical Neurology and Neurosurgery （Clinical Neurology and Neurosurgery) 174 57 - 62 2018.11

ISSN 03038467

© 2018 Elsevier B.V. Objective: To evaluate the pros and cons of using a newly developed microscope, ORBEYE™, during microneurosurgery. Patients and methods: ORBEYE™ use in 14 microneurosurgical procedures was retrospectively assessed by nine neurosurgeons after the procedure. A questionnaire comprising 20 questions was designed and used for evaluation. Results: Compared with the current gold standard, the binocular microscope, ease of setting up the equipment was scored the highest, whereas ease of conducting surgery in a position of an assistant was scored the lowest. Among characteristics of ORBEYE™ itself, the space-saving feature was scored the highest and was followed by the ability to perform procedures in a comfortable position. The only characteristic that was rated below average was ease of operation in a position of an assistant. Neurosurgeons with greater experience (more than five procedures using ORBEYE™) provided significantly higher scores (p = 0.0196) for characteristics of ORBEYE™ itself compared with neurosurgeon with fewer ORBEYE™ experience. Conclusions: The main benefits of the ORBEYETM are its compact size and freedom from focusing through the eye lens of a conventional binocular microscope. However, it appears to be disadvantageous for operating in a position of an assistant because the surgical field has a rotated view on the monitor from a position of an assistant. Nonetheless, because of certain advantages, we believe the ORBEYE™ could be of additional help to use of conventional binocular microscope at the moment and will facilitate microneurosurgery in the future.

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Intraosseous venous structures adjacent to the jugular tubercle associated with an anterior condylar dural arteriovenous fistula.

Mizutani T, Akiyama T, Minami Y, Toda M, Fujiwara H, Jinzaki M, Yoshida K

Neuroradiology （Neuroradiology) 60 （ 5 ） 487 - 496 2018.05

ISSN 00283940

© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Purpose: Although involvement of the osseous component with an anterior condylar dural arteriovenous fistula (AC-DAVF) has been frequently described, osseous venous structures in which AC-DAVFs develop have not been fully elucidated. We investigated osseous venous structures adjacent to the hypoglossal canal in normal controls and patients with AC-DAVFs. Methods: The study included 50 individuals with unruptured aneurysms as normal controls and seven patients with AC-DAVFs. Osseous venous structures adjacent to the hypoglossal canal in normal controls were analyzed using computed tomography (CT) digital subtraction venography. In patients with AC-DAVFs, the fistulous pouches, draining veins, and surrounding venous structures were examined using cone beam CT. Results: In 46.0% of laterals in normal controls, osseous venous structures were visualized within the jugular tubercle superomedially to the hypoglossal canal. We named these structures the jugular tubercle venous complex (JTVC). The JTVC was always continuous with the anterior condylar vein and was sometimes connected to surrounding venous channels. We detected nine fistulous pouches in the seven patients with AC-DAVFs. The fistulous pouches were in the JTVC (33.3%), anterior condylar vein (33.3%), and other venous channels within the exoccipital region (33.3%). Conclusion: Although the JTVC is a venous structure frequently found in normal people, it had not been investigated until now. The venous channel between the anterior condylar vein and JTVC is a common origin site for AC-DAVFs, and it was associated with 66.6% of the AC-DAVF cases in the current study.

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A pilot study of peptide vaccines for VEGF receptor 1 and 2 in patients with recurrent/progressive high grade glioma.

Shibao S, Ueda R, Saito K, Kikuchi R, Nagashima H, Kojima A, Kagami H, Sasaki H,　Noji S, Kawakami Y, Yoshida K, Toda M

Oncotarget （Oncotarget) 9 （ 30 ） 21569 - 21579 2018.04

© Shibao et al. Object: Early-phase clinical studies of glioma vaccines have shown feasibility and encouraging preliminary clinical activity. A vaccine that targets tumor angiogenesis factors in glioma microenvironment has not been reported. Therefore, we performed a pilot study to evaluate the safety and immunogenicity of a novel vaccination targeting tumor angiogenesis with synthetic peptides for vascular endothelial growth factor (VEGF) receptor epitopes in patients with recurrent/progressive high grade gliomas. Methods: Eight patients received intranodal vaccinations weekly at a dose of 2mg/kg bodyweight 8 times. T-lymphocyte responses against VEGF receptor (VEGFR) epitopes were assessed by enzyme linked immunosorbent spot assays. Results: This treatment was well-tolerated in patients. The first four vaccines induced positive immune responses against at least one of the targeted VEGFR epitopes in the peripheral blood mononuclear cells in 87.5% of patients. The median overall survival time in all patients was 15.9 months. Two achieved progression-free status lasting at least 6 months. Two patients with recurrent GBM demonstrated stable disease. Plasma IL-8 level was negatively correlated with overall survival. Conclusion: These data demonstrate the safety and immunogenicity of VEGFR peptide vaccines targeting tumor vasculatures in high grade gliomas.

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The analysis of the cerebral venous blood volume in cavernous sinus using 320 row multi-detector CT.

Mizutania K, Toda M,　Yajima Y, Akiyama T, Fujiwara H, Yoshida K, Jinzaki M

Clin Neurol Neurosurg （Clinical Neurology and Neurosurgery) 167 11 - 16 2018.04

ISSN 03038467

© 2018 Elsevier B.V. Objectives: : Functional venous anatomy in the brain has been mostly understood from the morphological and embryological points of view and no published study has directly evaluated the blood flow volume of cerebral small veins. We developed a method to directly evaluate the relative blood volume in small venous channels using multi-detector computed tomography (CT) and applied it to evaluate the blood volume in each tributary of the cavernous sinus, which plays an important role in cerebral venous drainage. Patients and Methods: : Ten patients with small brain tumors who had normal venous anatomy were included in the present study. All of them underwent preoperative 320-row multi-detector CT. After injecting the contrast bolus, we measured the Hounsfield units (HUs) at 10 time point over 60 s in each tributary of the cavernous sinus. The gamma distribution fitting to each HU enabled us to obtain a time-density curve and determine the relative venous volume in each venous channel. Results: : In terms of blood volume, the superficial middle cerebral vein and inferior petrosal sinus were the largest inflow and outflow channels of the cavernous sinus and accounted for 36.1% and 24.7% of its inflow and outflow on average, respectively. The superior orbital vein did not contribute to the blood volume passing through the cavernous sinus in the current study. Conclusions: : The present study allowed us to determine the relative blood volume in each tributary of the cavernous sinus, which was very useful to understand the physiological actual venous drainage pattern concerning the cavernous sinus in normal anatomy.

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An Analysis of Various Tracts of Mastoid Air Cells Related to Cerebrospinal Fluid Leak after the Anterior Transpetrosal Approach.

Tamura R,　Tomio　R,　Mohammad　F,　Toda　M, Yoshida　K

Journal of Neurosurgery 16 1 - 8 2018.03

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Histopathological vascular investigation of the peritumoral brain zone of glioblastomas.

Tamura R, Ohara K, Sasaki H, Morimoto Y, Yoshida K, Toda M.

J Neurooncol （Journal of Neuro-Oncology) 136 （ 2 ） 233 - 241 2018.01

ISSN 0167594X

© 2017, Springer Science+Business Media, LLC. To date, no histopathological vascular investigation focusing on peritumoral brain zone (PBZ) has been reported for glioblastoma. We analyzed 10 newly diagnosed cases of glioblastomas. For these PBZs, histopathological investigation was performed by hematoxylin–eosin (H&E) staining and immunohistochemistry was analyzed for CD31, CD34, Factor VIII, VEGF, VEGFR-1/2, Ki67, p53 and nestin. Although it was difficult to identify PBZ by H&E, Ki67 and p53 staining, there were apparent differences in nestin staining among PBZ, tumor core (TC), and normal zone (NZ). Therefore, in this study, we divided PBZ from TC and NZ by nestin staining. Differences in histological features, microvessel density, expression of VEGF and its receptors were assessed for PBZ, TC and NZ. The microvessel density, as determined by counting CD31, CD34 and VEGF receptors, and VEGF-A expression were lower in PBZ than TC. The expression patterns for CD31, CD34 and VEGF receptors in vessels show dissociation in PBZ. In addition, the vascular characteristics of the PBZ may correlate with findings of radiographic imaging. We provide the first clinicopathological evidence that PBZ exhibits unique angiogenic characteristics. These in situ observations will help to elucidate the mechanisms of tumor recurrence.

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Combined endoscopic endonasal and video-microscopic transcranial approach with preoperative embolization for a posterior pituitary tumor.

Yoshida Keisuke, Toda M, Akiyama T, Takahashi S, Nishimoto M, Ozawa H, Ikari Y, Yoshida K

World Neurosurgery （World Neurosurgery) 119 201 - 208 2018

ISSN 18788750

© 2018 Elsevier Inc. Background: Posterior pituitary tumor is rare, and its optimal surgical strategy is undetermined. Surgical removal of posterior pituitary tumors is often complicated by their hypervascularity. Prevention and preparation for excessive hemorrhage is crucial for safe resection. Case Description: A 69-year-old woman presented with bitemporal hemianopsia and was found to have a sellar tumor with suprasellar extension, resembling a pituitary adenoma. Microscopic transsphenoidal resection was attempted but was interrupted by a massive intraoperative hemorrhage. Pathologic diagnosis was a spindle cell oncocytoma, and she was referred to our institution. She underwent preoperative embolization to decrease tumor vascularity, and resection was performed using a combined endoscopic endonasal and video-microscopic transcranial approach, using a 4K three-dimensional (3D) video microscope. The final diagnosis was a posterior pituitary tumor with immunopositivity for thyroid transcription factor-1, with preferred interpretation as a pituicytoma. Conclusions: A combined endonasal and transcranial approach with preoperative embolization is a useful strategy for hypervascular posterior pituitary tumors. A 4K 3D video microscope is compact, and it provides high-resolution images, contributing larger surgical space and facilitating a multi-team surgery.

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Surgical treatment of cavernous sinus lesion in patients with non-functioning pituitary adenomas via the endoscopic endonasal approach.

Toda M, Kosugi K, Ozawa H, Ogawa K, Yoshida K

J Neurol Surg B Skull Base （Journal of Neurological Surgery, Part B: Skull Base) in press （ 5 ） S311 - S315 2018

ISSN 2193634X

© 2018 Georg Thieme Verlag KG Stuttgart . New York. Objective The main purpose of this article is to assess the effectiveness and safety of surgery via the endoscopic endonasal approach (EEA) for cavernous sinus (CS) lesion in patients with nonfunctioning pituitary adenomas (NFPA). Design Retrospective study. Setting Keio University Hospital. Participants Thirty patients who underwent CS surgery via the EEA between 2009 and 2017 for Knosp grade 4 NFPA with pre- and postoperative magnetic resonance imaging available for volumetric analysis. Main Outcome Measures Clinical presentation, extent of resection, and surgical complications. Results Gross total and near total resection of CS tumors was achieved in 12/30 (40%) cases of Knosp grade 4 NFPA. The average resection rate of CS lesions in these 30 patients was 73.5%; 77.3% in primary cases and 70.1% in recurrent cases that did not vary significantly. Preoperative visual disturbance and oculomotor nerve palsy improved in 12/19 (63.1%) and - (60%) cases, respectively. Complications associated with CS via the EEA were postoperative cerebrospinal leakage (1/30, 3.3%), meningitis (1/30, 3.3%), and transient cranial nerve palsy (2/30, 6.7%). These complications except a case of mild transient abducens nerve palsy occurred in recurrent cases with subdural lesions. Conclusions Although the optimal management of CS lesions in NFPA is controversial, debulking via the EEA is an effective and safe option that improves neurological symptoms and enables effective adjuvant radiotherapy. Recurrent cases with subdural invasion are technically challenging, even using the EEA, and special care is required to avoid complications.

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Preoperative prediction of solitary fibrous tumor/hemangiopericytoma and angiomatous　meningioma using magnetic resonance imaging texture analysis

Kanazawa　T,　Toda M

World Neurosurgery （World Neurosurgery) in press e1208 - e1216 2018

ISSN 18788750

© 2018 Elsevier Inc. Background: Solitary fibrous tumor (SFT)/hemangiopericytoma (HPC) is radiologically difficult to distinguish from meningioma, especially angiomatous meningioma. This study aimed to detect texture parameters to distinguish SFT/HPC from angiomatous meningioma using magnetic resonance imaging texture analysis with commercially available software. Methods: We retrospectively investigated textural parameters in 43 newly diagnosed SFTs/HPCs, angiomatous meningiomas, and other World Health Organization (WHO) grade I meningiomas treated at Keio University Hospital. For T1 contrast-enhanced, T2, and apparent diffusion coefficient (ADC) images, texture analyses were performed. Regions of interest were drawn manually with reference to the greater signal on contrast-enhanced T1-weighted images. ADC values and texture parameters, including kurtosis, skewness, and entropy, were evaluated and compared between these 3 groups. Results: The mean ADC value was significantly high in angiomatous meningioma, compared with SFT/HPC and other WHO grade I meningioma. ADC entropy was highest in SFT/HPC, followed by angiomatous and other WHO grade I meningioma. T2 skewness was significantly high in SFT/HPC, compared with angiomatous and other WHO grade I meningioma. T1 contrast-enhanced skewness was significantly low in angiomatous meningioma, compared with other WHO grade I meningioma. Mean ADC value distinguished SFT/HPC from angiomatous meningioma with a positive predictive value (PPV) of 62.5% and specificity of 62.5%. ADC entropy distinguished SFT/HPC from angiomatous meningioma with a PPV of 100% and specificity of 100%. ADC skewness distinguished SFT/HPC from angiomatous meningioma with a PPV of 66.7% and specificity of 71.4%. Conclusions: This study demonstrated that magnetic resonance imaging texture analysis was useful for distinguishing SFT/HPC from meningioma, especially angiomatous meningioma.

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Treatment strategy for tuberculum sellae meningiomas based on a preoperative radiological assessment

Toda M

World Neurosurgery （World Neurosurgery) in press e1279 - e1288 2018

Research paper (scientific journal), ISSN 18788750

© 2018 Elsevier Inc. Background: Although there are several surgical approaches for the treatment of tuberculum sellae (TS) meningiomas, clear indications for non–large TS meningiomas are still lacking. Methods: Our case series included 20 patients with TS meningiomas (<3 cm). We classified the tumors into 3 groups based on their radiologic relationship with the optic chiasm: type I, tumor with intact optic chiasm; type II, tumor with superiorly deviated optic chiasm; and type III, tumor with posteriorly deviated optic chiasm. Clinical outcomes, radiologic findings, and surgical approaches for the removal of each tumor type were retrospectively reviewed. Results: Resections using a pterional approach, interhemispheric approach, and an endoscopic endonasal approach were performed in three groups of 6, 7, and 7 patients. The rate of total tumor resection was equivalent across approaches, whereas postoperative visual dysfunction was observed in 1 patient (7.69%) undergoing a transcranial approach. Our evaluation of the sphenoid sinus shape across radiographs revealed that the patterns of bony wall elongation attached to these tumors significantly differed among tumor types, indicating that tumor origin and growth direction might affect the patterns of optic chiasm deviation. In addition, selective elongation of the TS provided a favorable surgical corridor for an endoscopic endonasal approach, especially in type II tumors. These results indicate that this tumor classification influenced surgical approach selection for non–large TS meningiomas. Conclusions: The aim of surgery is maximal tumor resection without causing visual dysfunction. The classification proposed here may predict surgical risk associated with meningioma resection and further inform the selection of a surgical approach.

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Skull base venous anatomy associated with endoscopic skull base neurosurgery: a literature review

Toda M

World Neurosurgery （World Neurosurgery) in press 405 - 414 2018

ISSN 18788750

© 2018 Elsevier Inc. An understanding of the anatomy and function of the skull base venous channels is fundamentally important for safe performance of endoscopic surgery for skull base lesions. This review focuses on 4 skull base venous channels—namely, the intercavernous sinuses, basilar plexus, osseous veins, and inferior petroclival vein—because these have been less recognized by neurosurgeons than other major venous channels such as the inferior petrosal sinus. We reviewed the literature concerning these 4 venous channels and discussed their anatomy and function. The literature review was mainly based on an electronic search in PubMed using the following terms: “intercavernous sinus,” “basilar plexus,” “emissary veins,” “diploic vein,” “basilar plexus,” “intraosseous vein,” “inferior petroclival/petro-occipital vein,” and “transclival.” A total of 50 articles were included in this review. Detailed anatomic features of the 4 structures have been elucidated in the literature. All of these venous channels run along the skull base and have multiple connections with surrounding venous structures. Because of their location, they occasionally obstruct the surgical view and are sometimes implicated in intraoperative hemorrhage, air embolism during endoscopic skull base surgery, and postoperative hematoma. They usually function as a venous reservoir of cranial venous drainage; however, they are less often directly involved in normal brain perfusion. Knowledge about the functional and morphologic anatomy of the skull base venous channels is important for neurosurgeons to avoid unexpected complications during endoscopic skull base surgery.

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