Can Trigeminal Schwannomas in Middle Cranial Fossa Invade Cavernous Sinus

Can Trigeminal Schwannomas in Middle Cranial Fossa Invade Cavernous Sinus | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Can Trigeminal Schwannomas in Middle Cranial Fossa Invade Cavernous Sinus Jie Yin, Zhijun Yang, Yu Zhang, Heng Zhang, Yihao Wu, Zhe Zhang, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3983967/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This study reports trigeminal schwannomas (TSs) in 13 cases whose cancer invaded the cavernous sinus (CS) in the middle cranial fossa (MCF). Seventy-eight patients who underwent surgical treatment in Beijing Tiantan Hospital in the last 6 years were retrospectively analyzed and a literature review was conducted. The patients were divided into 2 groups by definitive evidence of CS invasion during surgery. Group A included 65 cases. Six patients suffered from diplopia. Tumor size in their MCF ranged from 7 mm to 48 mm (mean: 23.5 ± 8.0 mm), and the gross total resection(GTR) was 93.8%. Group B included 13 cases, among whom 5 developed diplopia (p < 0.05). Tumor size in their MCF ranged from 17 mm to 44 mm (mean: 30.0 ± 7.7 mm) (p < 0.05), and the GTR was 69.2% (p < 0.05). In patients with CS invasion, there was a higher incidence of diplopia and larger tumor diameter. Gender, age, classification, nature, width of channel, and other clinical symptoms did not show statistical significance. So the TSs can invade CS, which can lower GTR. Some features may help predict the invasion, and a thorough preoperative assessment is helpful. Trigeminal Schwannoma Cavernous Sinus Invasion Radiological images Diplopia Classification Surgical approach Figures Figure 1 Figure 2 Figure 3 Introduction Trigeminal schwannomas (TSs) develop from Schwann 's cells of the trigeminal sheath and account for 0.07% – 0.36% of intracranial tumors [ 1 ] . Trigeminal nerve arises from the pons, then crosses the petrous apex to reach the Meckel's space region and subsequently splits into three branches that extend extracranially through the superior orbital fissure (V1), foramen rotundum (V2), and foramen ovale (V3), respectively [ 2 ] . Thus, TSs can be found in the subdural, interdural, or extracranial space. Total surgical resection is regarded as the best treatment for this benign tumor [ 3 ] . Jefferson [ 4 ] , Samii [ 5 ] , Ramina [ 6 ] , Wanibuchi [ 1 ] , and Yoshida [ 7 ] et al have all proposed classifications according to the pattern of tumor growth. In addition, different surgical approaches have been suggested. TSs are interdural tumors in the middle cranial fossa(MCF) [ 8 ] , confined within the dural membranes of the lateral wall of the cavernous sinus(CS). Therefore, surgical exposure of the venous plexus of CS is rarely needed as a well-defined dural layer provides a reliable plane for surgical dissection [ 9 ] . In the current study, we retrospectively analyzed data from 78 patients with TS in the MCF. The tumor of 13 patients invaded the CS. The term “invasion” was only used if there was definitive evidence of CS invasion during surgery. Radiological images, clinical features, tumor characteristics, and surgical videos were compared between the tumors with and without CS invasion. The surgical strategies were discussed, and the previous literature was reviewed. Materials and methods Clinical data collection A single-center retrospective study was conducted, including 78 cases with pathologically comfirmed TSs in the MCF in the 7th Neurosurgical Oncology Ward of Beijing Tiantan Hospital from May 2017 to January 2023 (cases of schwannomatosis, NF-1 and NF-2 were excluded). Hospital records, radiological images, surgical videos, pre- and post-operative cranial nerve examination records, and follow-up records were analyzed. Tumor characteristics, and postoperative reexamination Preoperative CT, MRI, and contrast-enhanced MRI were used to assess tumor size in the MCF. Tumor size was classified into 4 groups: 4 cm [ 10 ] , and tumor texture was classified into cystic, solid, and mixed. The surgery was performed by the skull base tumor team from Beijing Tiantan Hospital, and neurophysiological monitoring was conducted during the operation. The gross extent of tumor removal (EOR) was classified into gross total resection (GTR), subtotal resection (STR, > 90%), and partial resection (PR, < 90%) by intraoperative observation and enhanced MRI within 3 days of the surgery. Follow-up investigations were performed at 3 months and 1 year after the surgery. Outpatient visits were performed every 1 or 2 years, including MRI-enhanced reexaminations and neurological examinations. The follow-up length ranged from one year to six years (mean 31 months), and the last follow-up was done on March 1, 2023. Pre-operative imaging predictors of CS invasion and criteria for grouping The predictors of invasion are as follows: a. tumor extends beyond the horizontal segment of the internal carotid artery(ICA) in axial images; b. tumor extends beyond the posterior genu of the ICA in coronal images; c. obscure boundary between the tumor and ICA and incomplete lateral wall of the CS. However, the bare wall of the cavernous ICA which could be identified in surgery, will be the unequivocal evidence for grouping. Statistical analysis A descriptive analysis of data was performed using the IBM SPSS Statistical Package 23.0. A probability value < 0.05 was considered statistically significant. A univariate analysis was used to compare clinical data (independent samples t test or Chi-square test). Results Patient statistics Seventy-eight patients were enrolled (46 male patients and 32 female patients with an age range of 12–67 years). Primary clinical symptoms included facial numbness, headache and diplopia. Fifteen cases had CS invasion when we used pre-operative radiological imaging predictors. However, according to intraoperative judgment, CS invasion was found in 13 patients. Then, 78 cases were divided into two groups: group A (65 patients without CS invasion) and group B (13 patients with CS invasion). In the current study, TSs were classified in the form of MPE [ 7 ] . The baseline information of patients is summarized in Table 1 . The male-to-female ratio was 36:29 in group A, and patients’ ages ranged from 12 to 67 years (mean: 44.4 ± 13.0 years). Thirty-two patients had facial numbness, 16 cases had headache, and 6 cases had diplopia in this group. Tumor size in the MCF ranged from 7 mm to 48 mm(mean: 23.5mm ± 8.0mm). Most tumors were Solid(52 cases) with some being mixed(13 cases). Twenty cases(30.8%) were classified as type M, 21 cases were classified as type ME, 22 cases were classified as type MP, and 2 cases were classified as type MPE. The GTR was 93.8%.The radiological images showed that tumors were confined within a well-defined dural layer, and an intact lateral wall of the CS was detected in surgery.(Fig. 1 ) In group B, the male-to-female ratio was 10:3, and patients’ ages ranged from 28 to 64 years (mean: 41.0 ± 10.3 years). Six patients had facial numbness, 3 cases had headache, and 5 cases had diplopia (p < 0.05). Tumor size in the MCF ranged from 17 mm to 44 mm (mean: 30.0 ± 7.7 mm) (p < 0.05). Most tumors were solid (9 cases), with some being mixed (4 cases). Six cases (46.2%) were classified as type M, 2 cases were classified as type ME, 3 cases were classified as type MP, and 2 cases were classified as type MPE. The GTR was 69.2% (p < 0.05). The radiological images showed the real infiltration of the lateral wall of the CS, and the tumor invaded beyond the ICA. The course of the intracavernous ICA was identified in surgery.(Fig. 2 ) Table 1 Clinical features and tumor characteristics No. of patients t / χ 2 p value Group A Group B Preoperative prediction 63 15 criteria for grouping 65 13 χ 2 = 0.174 p = 0.677 Clinical feature Gender Male 36(55.4%) 10(76.9%) Female 29 3 χ 2 = 2.08 p = 0.150 Age(years) 44.4 ± 13.0 41.0 ± 10.3 t = 0.875 p = 0.384 Presenting symptoms Facial numbness 32(49.2%) 6(46.2%) χ 2 = 0.041 p = 0.839 Headaches 16(24.6%) 3(23.1%) χ 2 = 0.014 p = 1.000 Diplopia 6(9.2%) 5(38.5%) χ 2 = 7.741 p = 0.020* Visual deterioration 5(7.7%) 1(7.7%) χ 2 = 0 p = 1.000 Tumor characteristics Diameter (mm) in the middle cranial fossa 23.5 ± 8.0 30.0 ± 7.7 t=-2.665 p = 0.009* 40 1 2 Classification Single region M 20(30.8%) 6(46.2%) χ 2 = 1.154 p = 0.452 Two regions ME 21 2 MP 22 3 Multiple regions MPE 2 2 Width of channel(mm) 17.6 ± 6.1 14.6 ± 5.9 t = 1.239 p = 0.221 Nature Solid 52(80.0%) 9(69.2%) Cystic 0 0 Mixed 13 4 χ 2 = 0.737 p = 0.624 EOR GTR 61(93.8%) 9(69.2%) STR 3 3 PR 1 1 χ 2 = 7.131 p = 0.03* Mean values are presented as mean ± SD, * p < 0.05. Surgical strategy (Table 2) For the whole series, the traditional skull base approach and the endoscopic endonasal approach (EEA) [ 11 , 12 ] were adopted for the total removal of TSs. The surgical strategy was as follows: epidural approach or subdural approach was adopted for patients with type M. The epidural approach is the standard anterior transpetrosal approach (ATPA) [ 13 ] , and the subdural approach is intradural ATPA [ 14 , 15 ] . Frontotemporal epidural approach (F-T EDA) [ 16 ] was adopted for patients with type E 1 M; EEA was adopted for patients with type E 2 M; and ATPA was adopted for patients with type MP. Retrosigmoid approach (RSA) was adopted for tumors only when the tumor diameter in the posterior cranial fossa (PCF) was much larger than that in the MCF. Suprameatal tuber was sometimes ground during the operation. [ 17 , 18 ] . For patients with MPE, F-T EDA or ATPA was the first choice. Table 2 Surgical approach according to the classification Classification No. of patients Surgical approach No. of patients Single zone M 26 ATPA 22 EEA 4 Two regions E 1 M 6 F-T EDA 5 EEA 1 E 2 M 17 EEA 14 ATPA 3 MP 25 ATPA 18 RSA 3 RSA + PSA 2 EEA 2 Multiple regions E 1 MP 1 F-T EDA 1 E 2 MP* 1 EEA 1 E 2 MP# 2 ATPA 2 Abbreviation: ATPA anterior transpetrosal approach; EEA endoscopic endonasal approach; F-T EDA fronto-temporal epidural approach; PSA presigmoid approach; RSA retrosigmoid approach; * tumor invading the pterygopalatine fossa ; # tumor invading the pterygopalatine fossa and infratemporal fossa . Discussion TSs are benign tumors with slow growth that can develop anywhere in the intracranial and extracranial regions due to the course of the trigeminal nerve [19] . The course of the trigeminal nerve mainly involves 4 anatomical regions, including the trigeminal root in the PCF (subdural space), the trigeminal root or gasserian ganglion (GG) in the area of Meckel's capsule (interdural space), the trigeminal branches of the interdural structures, and the extracranial peripheral branches of the trigeminal nerve (epidural space) [20] . The benign nature of TSs and their compressive effects on peripheral neurovascular structures indicate that most TSs should be completely resected. Different experts have made different recommendations about the classification of TS and its surgical treatmen [1, 4-7, 21, 22] . Jefferson et al. [4] classified TSs into three groups. Type A tumors are located in the MCF, type B tumors are located in the PCF, and type C tumors are located in both fossa. Samii et al. [5] described tumors in the extracranial fossa as another type D. Wanibuchi et al. [1] attempted to propose a simple classification with surgical approaches. They suggested that the peripheral type(type D) of TS can be refined based on the invasion of V1, V2, and V3. Dumbbell-shaped tumors were further classified as cavernous root (occupying both the MCF and PCF) and cavernous peripheral (occupying both the middle and extracranial portions). Ramina et al. [6] classified TSs according to the location of the main mass and the form of extension into the following types: extracranial tumor with MCF extension, MCF with extracranial extension, and middle, posterior and extracranial tumor. Different classification corresponds to different surgical strategies. The MPE classification of TSs proposed by Yoshida [7, 10] was used in the current study, which divided TSs into three regions based on the location of the tumors. TSs existing in the lateral wall of the CS and/or Meckel’s cave were regarded as type M; TSs occupying the PCF were classified as type P; and TSs existing in extracranial regions were classified as type E, with E 1 representing tumors in orbital fossa and E 2 representing tumors in infratemporal or pterygopalatine fossa. [7, 10] In this study, we investigated the relationship between the tumors in the MCF and the dural membranes of the lateral wall of the CS.according to this classification. Our surgical strategy is based on this MPE classification. Although traditional skull base approaches improved the GTR and reduced surgical complications, the advancement of endoscopic technology has improved skull base approaches and decreased iatrogenic trauma [1, 10, 23] . EEA provides access to tumors in the pterygopalatine fossa, infratemporal fossa, medial orbit, and MCF [24] . EEA can expose the tumor on the extension and facilitate the separation and total resection of the tumor [25, 26] . For type ME TSs, the pterygopalatine fossa and infratemporal fossa can be accessed along the nasal channel. Then, the Meckel's cavity was accessed through the “natural” tumor corridor [27] . For type M TSs, the anterior wall of the Meckel's cavity was opened in the quadrangular region [28] , and the tumor was resected by entering the anteromedial aspect of the Meckel's cavity without traction by separating the dural periosteal layer and the space between the trigeminal nerve [12] .However, the relationship between the tumor and the lateral wall of the CS should be taken into account in such surgeries, because of the high risk of bleeding from the venous plexus and the possible intraoperative injury of the ICA, especially when removing the tumors by EEA. The lateral wall of the posteroinferior segment of the CS venous plexus is formed by the upper one-third of Meckel's cave, which covers a portion of the GG, and gives rise to V1. When the tumor originates from the GG or the anterior extension (V1), it lies the interdural space of the CS lateral wall (between the dura propria and the inner membranous layer). [29] Xu Y, et al. [30] elaborated on the intracranial routes by which pituitary adenomas invaded (from inside to outside) and identified the 3 potential breakthrough locations in the CS through the superior, lateral, and posterior compartments, including superior triangle (oculomotor triangle), lateral triangle, and posterior triangle. The breakthrough route through the lateral compartment (lateral triangle) is delimited by the anterior petroclinoidal ligament (APCL) superiorly and the V1 inferiorly. [30] TSs can invade the CS from outside to inside based on this anatomical relationship (thin inner membranous layer and lateral potential breakthrough location). We searched for previous studies on the relationship between TSs and CS. Wanibuchi et al . [1] indicated that TS is unlikely to invade the lateral wall of the CS, most TSs could be dissected off the lateral wall of the CS. However, he found “VAFE”-type (vascular, adherent, fibrous, and engulfing) tumors, which were adhered to the adjacent nerves, ICA, etc. Goel et al. [8, 9, 23] reported that TSs are generally interdural tumors with well-defined meningeal boundaries. Transgression of the dural boundaries was almost never seen, even in massive tumors. In their study, the venous compartment of ICA was displaced rather than invaded. Komatsu et al . [31] proposed that TSs do not infiltrate into the CS or subdural space. Dolenc et al. [16] found that TSs were located in the inter-dural space. Yoshida et al . observed that TSs were covered with the inner layer [32] , indicating that most M-type TSs arose from the lateral wall of the CS or Meckel’s cave lesions. [10] . Chen et al. [21] did not observe CS invasion in 55 patients. However, Samii et al. [18] found 1 case with TS invading the CS. In current study, we obtained different results. We retrospectively analyzed data from 78 patients with TSs whose tumors occupied the MCF, and detected that tumors invading the CS in 13 cases(16.7%). Then, we compared the clinical features and tumor characteristics of the two groups and found that there were higher incidences of diplopia, larger tumor diameter in the MCF and lower GTR when TSs invaded the CS. There was no statistically significant difference in gender, age, classification, nature, width of channel, and other clinical symptoms. It was considered that the abducent nerve was encased when TS invaded the CS, resulting in diplopia. Surprisingly, the classification and the width of the communicating channel did not show a statistically significant difference between these two groups, indicating that the reason of the CS breakthrough is invasion of the lateral wall rather than compression. There were 2 cases of 15 cases with radiographic suspicion but no true invasion. ICA was encased by the tumor, but the thin inner membranous layer was intact during the surgery. Tumor sizes in the MCF were 23 mm and 25 mm, and the tumors did not cause diplopia. Due to the effectiveness of radiotherapy, conservative treatment of the tumor in the CS is recommended, which also reduces morbidity without sacrificing tumor control [33] . However, Surgical strategies should help maximize tumor resection while minimizing the morbidity of these large tumors. Only this will reduce postoperative recurrence. The CS is more likely to be opened to remove the intracavernous tumor if the tumor is expected to be soft. Because of their delicate nature, these tumors are easily sucked out and separated from the intracavernous ICA and cranial nerves. [34] Even when the tumor is tough and difficult to remove, the "natural" corridor to the CS provided by the tumor can help its complete resection with CUSA. However, it may be difficult to dissect the tumor without neurovascular injury. During dissection in 1 case, the ICA ruptured due to the tough nature of the tumor and its tight adhesion to the ICA. A vascular suture was employed after temporary occlusion, and the tumor was completely removed ( Figure 3 ). Therefore, it is critical to preoperatively assess the relationship between the tumor and ICA and measure the texture of the tumor. For tumors with CS invasion, the transcranial approach appears to be superior to EEA because it allows possible suturing of the ruptured artery. Although it has been rarely reported that TS can invade the lateral wall of the CS, we believe that the phenomenon is not rare. This type of TSs may be more invasive than others. No reliable radiological method can accurately evaluate whether a tumor invaded the CS, which can be the potential reason for lower GTR. Based on our experience, some clues may best predict true CS invasion, such as the clinical symptom of diplopia, a larger diameter of the tumor in the MCF, the incomplete lateral wall of the CS, and the tumor beyond the ICA in preoperative radiological images. These data can help preoperative planning and protect the tissues and vascular structures. Limitation The molecular pathology of TSs with CS invasion needs further studies. High-resolution MRI with thin slice scan and high-definition 3D modeling on radiological images will be beneficial for an accurate preoperative evaluation, although further studies are still needed. Conclusion Seventy-eight patients with TSs occupying the MCF were surgically treated. TSs can invade the CS, which can lower GTR. Some clues may help predict the CS invasion, such as the clinical symptom of diplopia, the large diameter of the tumor in the MCF, and tumor invasion beyond the ICA in radiographic images. A thorough preoperative evaluation can be helpful. Declarations Acknowledgement The authors sincerely thank all colleagues of the neurosurgery department in Tiantan Hospital. Author Contributions Yu Zhang, Heng Zhang, Jie Yin were jointly responsible for the analysis of the data and writing of the paper. Zhe Zhang participated in the linguistic polishing of the manuscript. Minjun Yan and Yihao Wu helped search the literature, while Zhijun Yang was responsible for data collation. Pinan Liu was responsible for reviewing improvements and financial support. Funding No funding. Data availability The analyzed data sets generated during the present study are available from the corresponding author on reasonable request. Compliance with ethical standards Conflict of interest The authors declare that they have no conflicts of interest. 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Xu Y, Mohyeldin A, Asmaro KP et al (2022) Intracranial Breakthrough Through Cavernous Sinus Compartments: Anatomic Study and Implications for Pituitary Adenoma Surgery. Oper Neurosurg (Hagerstown) 23(2):115–124 Komatsu F, Komatsu M, Di Ieva A, Tschabitscher M (2012) Endoscopic approaches to the trigeminal nerve and clinical consideration for trigeminal schwannomas: a cadaveric study. J Neurosurg 117(4):690–696 Kobayashi M, Yoshida K, Kawase T (2010) Inter-dural approach to parasellar tumors. Acta Neurochir (Wien). 152(2): 279 – 84; discussion 284-5. Peciu-Florianu I, Régis J, Levivier M, Dedeciusova M, Reyns N, Tuleasca C (2021) Tumor control and trigeminal dysfunction improvement after stereotactic radiosurgery for trigeminal schwannomas: a systematic review and meta-analysis. Neurosurg Rev 44(5):2391–2403 Sun DQ, Menezes AH, Howard MA 3rd, Gantz BJ, Hasan DM, Hansen MR (2018) Surgical Management of Tumors Involving Meckel's Cave and Cavernous Sinus: Role of an Extended Middle Fossa and Lateral Sphenoidectomy Approach. Otol Neurotol 39(1):82–91 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3983967","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":275497444,"identity":"5c61129a-613d-4816-a03d-f9fc2b6e4d74","order_by":0,"name":"Jie Yin","email":"","orcid":"","institution":"Capital Medical University","correspondingAuthor":false,"prefix":"","firstName":"Jie","middleName":"","lastName":"Yin","suffix":""},{"id":275497445,"identity":"f46f0734-0e24-441a-8e7d-dc94aab09d7a","order_by":1,"name":"Zhijun Yang","email":"","orcid":"","institution":"Capital Medical University","correspondingAuthor":false,"prefix":"","firstName":"Zhijun","middleName":"","lastName":"Yang","suffix":""},{"id":275497446,"identity":"488031c6-857d-4f10-8df3-1375d35c5812","order_by":2,"name":"Yu Zhang","email":"","orcid":"","institution":"Capital Medical University","correspondingAuthor":false,"prefix":"","firstName":"Yu","middleName":"","lastName":"Zhang","suffix":""},{"id":275497447,"identity":"56c3bd79-1885-41fb-b045-e15e2862250a","order_by":3,"name":"Heng Zhang","email":"","orcid":"","institution":"Xuzhou Central Hospital","correspondingAuthor":false,"prefix":"","firstName":"Heng","middleName":"","lastName":"Zhang","suffix":""},{"id":275497448,"identity":"9273287c-ae2d-49ee-a9a5-9b2f9b31a2b4","order_by":4,"name":"Yihao Wu","email":"","orcid":"","institution":"Xuzhou Central Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yihao","middleName":"","lastName":"Wu","suffix":""},{"id":275497449,"identity":"0bdfae49-6efd-499b-b838-f593e6292e53","order_by":5,"name":"Zhe Zhang","email":"","orcid":"","institution":"Capital Medical University","correspondingAuthor":false,"prefix":"","firstName":"Zhe","middleName":"","lastName":"Zhang","suffix":""},{"id":275497450,"identity":"f406c0d3-30be-4c2e-95cb-e3bc27f4df9c","order_by":6,"name":"Minjun Yan","email":"","orcid":"","institution":"Capital Medical University","correspondingAuthor":false,"prefix":"","firstName":"Minjun","middleName":"","lastName":"Yan","suffix":""},{"id":275497451,"identity":"e244b978-541f-42c0-a1c5-3c4b33aa4217","order_by":7,"name":"Pinan Liu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAzklEQVRIiWNgGAWjYDACZhBRIMHAD+UzNhCnxUCCQbKBaC1gYABEB4jVYs7Oe/BzgYFF4ubjh59u5mGwkd1wgPnZA3xaLJv5kqVnGEgkbjuTZnabhyHNeMMBNnMDvE46zGMgzQPScoOHDajlcOKGAzxsEgS0GP8Gadk8A6zlP1FazMC2bJAAazlAWItlM4+ZNVCL8QygX27OMUg2nnmYzQyvFnP+M8a3eSrqZPvbDz+78abCTrbvePMz/A7D5DLjU4+pZRSMglEwCkYBFgAAnJFAX8XXE2sAAAAASUVORK5CYII=","orcid":"","institution":"Capital Medical University","correspondingAuthor":true,"prefix":"","firstName":"Pinan","middleName":"","lastName":"Liu","suffix":""}],"badges":[],"createdAt":"2024-02-24 05:16:00","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3983967/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3983967/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":52042325,"identity":"4c3ca974-926e-4205-af49-8352d49b6f6d","added_by":"auto","created_at":"2024-03-05 18:33:49","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":5238526,"visible":true,"origin":"","legend":"\u003cp\u003eTSs without cavernous sinus (CS) invasion: A-C Radiological images showed the compression of the CS, and the tumor did not beyond the internal carotid artery (ICA). The yellow arrow indicate the intact lateral wall of the CS. D Intraoperative images showed an intact lateral wall* of the CS.\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-3983967/v1/0e8b237a38f574e660f73f3d.png"},{"id":52042323,"identity":"c23f527b-79e3-449f-88a2-a800e1686910","added_by":"auto","created_at":"2024-03-05 18:33:49","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":5493322,"visible":true,"origin":"","legend":"\u003cp\u003eTSs with cavernous sinus (CS) invasion: A-C Radiological images showed an obscure boundary between the tumor and the CS and the real infiltration into the lateral wall of the CS. The tumor invaded beyond the internal carotid artery (ICA). D Intraoperative images showed that the tumor invaded the venous space, and the intracavernous ICA* was identified.\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-3983967/v1/0e3ba93115b0e159976c7d5c.png"},{"id":52042322,"identity":"fe0c1626-cb90-4566-bae6-f16c2c9d9b03","added_by":"auto","created_at":"2024-03-05 18:33:49","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":5293827,"visible":true,"origin":"","legend":"\u003cp\u003eTSs with cavernous sinus (CS) invasion: A Tumor (T) was tough with tight adhesion to the internal carotid artery (ICA). B The rupture of the ICA was exposed. The yellow arrow indicates the ruptured arterial wall. C ICA was sutured with temporary occlusion. D Tumor was completely removed and the ICA was patent.\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-3983967/v1/8d44c2bd26bc268afa75bea8.png"},{"id":52636562,"identity":"a0c2cf14-f296-441e-8fa0-b3e77a906baf","added_by":"auto","created_at":"2024-03-13 23:22:43","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6914197,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3983967/v1/b6e6fee6-e35e-4715-81a3-ca8fdb9a7267.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Can Trigeminal Schwannomas in Middle Cranial Fossa Invade Cavernous Sinus","fulltext":[{"header":"Introduction","content":"\u003cp\u003eTrigeminal schwannomas (TSs) develop from Schwann 's cells of the trigeminal sheath and account for 0.07% \u0026ndash; 0.36% of intracranial tumors\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e. Trigeminal nerve arises from the pons, then crosses the petrous apex to reach the Meckel's space region and subsequently splits into three branches that extend extracranially through the superior orbital fissure (V1), foramen rotundum (V2), and foramen ovale (V3), respectively \u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e. Thus, TSs can be found in the subdural, interdural, or extracranial space. Total surgical resection is regarded as the best treatment for this benign tumor\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e. Jefferson\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e, Samii\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e, Ramina\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e, Wanibuchi\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e, and Yoshida\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e et al have all proposed classifications according to the pattern of tumor growth. In addition, different surgical approaches have been suggested. TSs are interdural tumors in the middle cranial fossa(MCF)\u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e, confined within the dural membranes of the lateral wall of the cavernous sinus(CS). Therefore, surgical exposure of the venous plexus of CS is rarely needed as a well-defined dural layer provides a reliable plane for surgical dissection\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. In the current study, we retrospectively analyzed data from 78 patients with TS in the MCF. The tumor of 13 patients invaded the CS. The term \u0026ldquo;invasion\u0026rdquo; was only used if there was definitive evidence of CS invasion during surgery. Radiological images, clinical features, tumor characteristics, and surgical videos were compared between the tumors with and without CS invasion. The surgical strategies were discussed, and the previous literature was reviewed.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eClinical data collection\u003c/h2\u003e \u003cp\u003eA single-center retrospective study was conducted, including 78 cases with pathologically comfirmed TSs in the MCF in the 7th Neurosurgical Oncology Ward of Beijing Tiantan Hospital from May 2017 to January 2023 (cases of schwannomatosis, NF-1 and NF-2 were excluded). Hospital records, radiological images, surgical videos, pre- and post-operative cranial nerve examination records, and follow-up records were analyzed.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eTumor characteristics, and postoperative reexamination\u003c/h2\u003e \u003cp\u003ePreoperative CT, MRI, and contrast-enhanced MRI were used to assess tumor size in the MCF. Tumor size was classified into 4 groups: \u0026lt;2 cm, 2\u0026ndash;3 cm, 3\u0026ndash;4 cm, and \u0026gt;\u0026thinsp;4 cm\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e, and tumor texture was classified into cystic, solid, and mixed. The surgery was performed by the skull base tumor team from Beijing Tiantan Hospital, and neurophysiological monitoring was conducted during the operation. The gross extent of tumor removal (EOR) was classified into gross total resection (GTR), subtotal resection (STR, \u0026gt;\u0026thinsp;90%), and partial resection (PR, \u0026lt;\u0026thinsp;90%) by intraoperative observation and enhanced MRI within 3 days of the surgery. Follow-up investigations were performed at 3 months and 1 year after the surgery. Outpatient visits were performed every 1 or 2 years, including MRI-enhanced reexaminations and neurological examinations. The follow-up length ranged from one year to six years (mean 31 months), and the last follow-up was done on March 1, 2023.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePre-operative imaging predictors of CS invasion and criteria for grouping\u003c/h3\u003e\n\u003cp\u003eThe predictors of invasion are as follows: a. tumor extends beyond the horizontal segment of the internal carotid artery(ICA) in axial images; b. tumor extends beyond the posterior genu of the ICA in coronal images; c. obscure boundary between the tumor and ICA and incomplete lateral wall of the CS. However, the bare wall of the cavernous ICA which could be identified in surgery, will be the unequivocal evidence for grouping.\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eA descriptive analysis of data was performed using the IBM SPSS Statistical Package 23.0. A probability value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant. A univariate analysis was used to compare clinical data (independent samples t test or Chi-square test).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003ePatient statistics\u003c/h2\u003e \u003cp\u003eSeventy-eight patients were enrolled (46 male patients and 32 female patients with an age range of 12\u0026ndash;67 years). Primary clinical symptoms included facial numbness, headache and diplopia. Fifteen cases had CS invasion when we used pre-operative radiological imaging predictors. However, according to intraoperative judgment, CS invasion was found in 13 patients. Then, 78 cases were divided into two groups: group A (65 patients without CS invasion) and group B (13 patients with CS invasion). In the current study, TSs were classified in the form of MPE\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e. The baseline information of patients is summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eThe male-to-female ratio was 36:29 in group A, and patients\u0026rsquo; ages ranged from 12 to 67 years (mean: 44.4\u0026thinsp;\u003cb\u003e\u0026plusmn;\u003c/b\u003e\u0026thinsp;13.0 years). Thirty-two patients had facial numbness, 16 cases had headache, and 6 cases had diplopia in this group. Tumor size in the MCF ranged from 7 mm to 48 mm(mean: 23.5mm\u0026thinsp;\u003cb\u003e\u0026plusmn;\u003c/b\u003e\u0026thinsp;8.0mm). Most tumors were Solid(52 cases) with some being mixed(13 cases). Twenty cases(30.8%) were classified as type M, 21 cases were classified as type ME, 22 cases were classified as type MP, and 2 cases were classified as type MPE. The GTR was 93.8%.The radiological images showed that tumors were confined within a well-defined dural layer, and an intact lateral wall of the CS was detected in surgery.(Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eIn group B, the male-to-female ratio was 10:3, and patients\u0026rsquo; ages ranged from 28 to 64 years (mean: 41.0\u0026thinsp;\u003cb\u003e\u0026plusmn;\u003c/b\u003e\u0026thinsp;10.3 years). Six patients had facial numbness, 3 cases had headache, and 5 cases had diplopia (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Tumor size in the MCF ranged from 17 mm to 44 mm (mean: 30.0\u0026thinsp;\u003cb\u003e\u0026plusmn;\u003c/b\u003e\u0026thinsp;7.7 mm) (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Most tumors were solid (9 cases), with some being mixed (4 cases). Six cases (46.2%) were classified as type M, 2 cases were classified as type ME, 3 cases were classified as type MP, and 2 cases were classified as type MPE. The GTR was 69.2% (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The radiological images showed the real infiltration of the lateral wall of the CS, and the tumor invaded beyond the ICA. The course of the intracavernous ICA was identified in surgery.(Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eClinical features and tumor characteristics\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" morerows=\"1\" nameend=\"c2\" namest=\"c1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eNo. of patients\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003et / χ 2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003ep value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eGroup A\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eGroup B\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003ePreoperative prediction\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003ecriteria for grouping\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eχ 2\u0026thinsp;=\u0026thinsp;0.174\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.677\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eClinical feature\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e36(55.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e10(76.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eχ 2\u0026thinsp;=\u0026thinsp;2.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.150\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eAge(years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e44.4\u0026thinsp;\u0026plusmn;\u0026thinsp;13.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e41.0\u0026thinsp;\u0026plusmn;\u0026thinsp;10.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;0.875\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.384\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003ePresenting symptoms\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFacial numbness\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e32(49.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6(46.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eχ 2\u0026thinsp;=\u0026thinsp;0.041\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.839\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHeadaches\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16(24.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3(23.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eχ 2\u0026thinsp;=\u0026thinsp;0.014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;1.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDiplopia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6(9.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5(38.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eχ 2\u0026thinsp;=\u0026thinsp;7.741\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.020*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVisual deterioration\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5(7.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1(7.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eχ 2\u0026thinsp;=\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;1.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTumor characteristics\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eDiameter (mm) in the middle cranial fossa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e23.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30.0\u0026thinsp;\u0026plusmn;\u0026thinsp;7.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003et=-2.665\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.009*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20\u0026ndash;30(including 30)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u0026ndash;40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eClassification\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSingle region\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20(30.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6(46.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eχ 2\u0026thinsp;=\u0026thinsp;1.154\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.452\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTwo regions\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eME\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMultiple regions\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMPE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eWidth of channel(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17.6\u0026thinsp;\u0026plusmn;\u0026thinsp;6.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e14.6\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;1.239\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.221\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eNature\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSolid\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e52(80.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9(69.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCystic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMixed\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eχ 2\u0026thinsp;=\u0026thinsp;0.737\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.624\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eEOR\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGTR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e61(93.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9(69.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSTR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eχ 2\u0026thinsp;=\u0026thinsp;7.131\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.03*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eMean values are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD, \u003cb\u003e*\u003c/b\u003e p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eSurgical strategy\u003c/b\u003e(Table\u0026nbsp;2)\u003c/p\u003e \u003cp\u003eFor the whole series, the traditional skull base approach and the endoscopic endonasal approach (EEA)\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e were adopted for the total removal of TSs. The surgical strategy was as follows: epidural approach or subdural approach was adopted for patients with type M. The epidural approach is the standard anterior transpetrosal approach (ATPA)\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e, and the subdural approach is intradural ATPA\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e. Frontotemporal epidural approach (F-T EDA)\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e was adopted for patients with type E\u003csub\u003e1\u003c/sub\u003eM; EEA was adopted for patients with type E\u003csub\u003e2\u003c/sub\u003eM; and ATPA was adopted for patients with type MP. Retrosigmoid approach (RSA) was adopted for tumors only when the tumor diameter in the posterior cranial fossa (PCF) was much larger than that in the MCF. Suprameatal tuber was sometimes ground during the operation. \u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. For patients with MPE, F-T EDA or ATPA was the first choice.\u003c/p\u003e\u003c/div\u003e\n\u003cp\u003eTable 2 Surgical approach according to the classification\u003c/p\u003e\n\u003cdiv\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"485\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003eClassification\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003eNo. of patients\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003eSurgical approach\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003eNo. of patients\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003eSingle zone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003eATPA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003eEEA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003eTwo regions\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003eE\u003csub\u003e1\u003c/sub\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003eF-T EDA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003eEEA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003eE\u003csub\u003e2\u003c/sub\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003eEEA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003eATPA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003eMP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003eATPA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003eRSA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003eRSA + PSA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003eEEA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003eMultiple regions\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003eE\u003csub\u003e1\u003c/sub\u003eMP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003eF-T EDA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003eE\u003csub\u003e2\u003c/sub\u003eMP*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003eEEA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.123711340206185%\" valign=\"bottom\"\u003e\n \u003cp\u003eE\u003csub\u003e2\u003c/sub\u003eMP#\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.824742268041238%\" valign=\"bottom\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.75257731958763%\" valign=\"bottom\"\u003e\n \u003cp\u003eATPA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.298969072164947%\" valign=\"bottom\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eAbbreviation: ATPA anterior transpetrosal approach; EEA endoscopic endonasal approach; F-T EDA fronto-temporal epidural approach; PSA presigmoid approach; RSA retrosigmoid approach; * tumor invading the pterygopalatine fossa\u003c/a\u003e; #\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003etumor invading the pterygopalatine fossa\u003c/a\u003e and infratemporal fossa\u003c/a\u003e.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eTSs are benign tumors with slow growth that can develop anywhere in the intracranial and extracranial regions due to the course of the trigeminal nerve\u003csup\u003e[19]\u003c/sup\u003e. The course of the trigeminal nerve mainly involves 4 anatomical regions, including the trigeminal root in the PCF (subdural space), the trigeminal root or gasserian ganglion (GG) in the area of Meckel\u0026apos;s capsule (interdural space), the trigeminal branches of the interdural structures, and the extracranial peripheral branches of the trigeminal nerve (epidural space)\u003csup\u003e[20]\u003c/sup\u003e. The benign nature of TSs and their compressive effects on peripheral neurovascular structures indicate that most TSs should be completely resected. Different experts have made different recommendations about the classification of TS and its surgical treatmen\u003csup\u003e[1, 4-7, 21, 22]\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eJefferson \u003cem\u003eet al.\u003c/em\u003e\u003csup\u003e[4]\u003c/sup\u003e classified TSs into three groups. Type A tumors are located in the MCF, type B tumors are located in the PCF, and type C tumors are located in both fossa. Samii \u003cem\u003eet al.\u003c/em\u003e\u003csup\u003e[5]\u003c/sup\u003e described tumors in the extracranial fossa as another type D. Wanibuchi \u003cem\u003eet\u0026nbsp;al.\u003c/em\u003e\u003csup\u003e[1]\u003c/sup\u003e attempted to propose a simple classification with surgical approaches. They suggested that the peripheral type(type D) of TS can be refined based on the invasion of V1, V2, and V3. Dumbbell-shaped tumors were further classified as cavernous root (occupying both the MCF and PCF) and cavernous peripheral (occupying both the middle and extracranial portions). Ramina \u003cem\u003eet al.\u003c/em\u003e\u003csup\u003e[6]\u003c/sup\u003e classified TSs according to the location of the main mass and the form of extension into the following types: extracranial tumor with MCF extension, MCF with extracranial extension, and middle, posterior and extracranial tumor. Different classification corresponds to different surgical strategies. The MPE classification of TSs proposed by Yoshida\u003csup\u003e[7, 10]\u003c/sup\u003e was used in the current study, which divided TSs into three regions based on the location of the tumors. TSs existing in the lateral wall of the CS and/or Meckel\u0026rsquo;s cave were regarded as type M; TSs occupying the PCF were classified as type P; and TSs existing in extracranial regions were classified as type E, with E\u003csub\u003e1\u003c/sub\u003e representing tumors in orbital fossa and E\u003csub\u003e2\u003c/sub\u003e representing tumors in infratemporal or pterygopalatine fossa.\u003csup\u003e[7, 10]\u003c/sup\u003e In this study, we investigated the relationship between the tumors in the MCF and the dural membranes of the lateral wall of the CS.according to this classification.\u003c/p\u003e\n\u003cp\u003eOur surgical strategy is based on this MPE classification. Although traditional skull base approaches improved the GTR and reduced surgical complications, the advancement of endoscopic technology has improved skull base approaches and decreased iatrogenic trauma\u003csup\u003e[1, 10, 23]\u003c/sup\u003e. EEA provides access to tumors in the pterygopalatine fossa, infratemporal fossa, medial orbit, and MCF\u003csup\u003e[24]\u003c/sup\u003e. EEA can expose the tumor on the extension and facilitate the separation and total resection of the tumor\u003csup\u003e[25, 26]\u003c/sup\u003e. For type ME TSs, the pterygopalatine fossa and infratemporal fossa can be accessed along the nasal channel. Then, the Meckel\u0026apos;s cavity was accessed through the \u0026ldquo;natural\u0026rdquo; tumor corridor\u003csup\u003e[27]\u003c/sup\u003e. For type M TSs, the anterior wall of the Meckel\u0026apos;s cavity was opened in the quadrangular region\u003csup\u003e[28]\u003c/sup\u003e, and the tumor was resected by entering the anteromedial aspect of the Meckel\u0026apos;s cavity without traction by separating the dural periosteal layer and the space between the trigeminal nerve\u003csup\u003e[12]\u003c/sup\u003e.However, the relationship between the tumor and the lateral wall of the CS should be taken into account in such surgeries, because of the high risk of bleeding from the venous plexus and the possible intraoperative injury of the ICA, especially when removing the tumors by EEA.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe lateral wall of the posteroinferior segment of the CS venous plexus is formed by the upper one-third of Meckel\u0026apos;s cave, which covers a portion of the GG, and gives rise to V1. When the tumor originates from the GG or the anterior extension (V1), it lies the interdural space of the CS lateral wall (between the dura propria and the inner membranous layer).\u003csup\u003e[29]\u003c/sup\u003e Xu Y, \u003cem\u003eet al.\u003c/em\u003e\u003csup\u003e[30]\u003c/sup\u003e elaborated on the intracranial routes by which pituitary adenomas invaded (from inside to outside) and identified the 3 potential breakthrough locations in the CS through the superior, lateral, and posterior compartments, including superior triangle (oculomotor triangle), lateral triangle, and posterior triangle. The breakthrough route through the lateral compartment (lateral triangle) is delimited by the anterior petroclinoidal ligament (APCL) superiorly and the V1 inferiorly.\u003csup\u003e[30]\u003c/sup\u003e TSs can invade the CS from outside to inside based on this anatomical relationship (thin inner membranous layer and lateral potential breakthrough location). We searched for previous studies on the relationship between TSs and CS. Wanibuchi \u003cem\u003eet al\u003c/em\u003e.\u003csup\u003e[1]\u003c/sup\u003e indicated that TS is unlikely to invade the lateral wall of the CS, most TSs could be dissected off the lateral wall of the CS. However, he found \u0026ldquo;VAFE\u0026rdquo;-type (vascular, adherent, fibrous, and engulfing) tumors, which were adhered to the adjacent nerves, ICA, etc. Goel \u003cem\u003eet al.\u003c/em\u003e\u003csup\u003e[8, 9, 23]\u003c/sup\u003e reported that TSs are generally interdural tumors with well-defined meningeal boundaries. Transgression of the dural boundaries was almost never seen, even in massive tumors. In their study, the venous compartment of ICA was displaced rather than invaded. Komatsu \u003cem\u003eet al\u003c/em\u003e.\u003csup\u003e[31]\u003c/sup\u003e proposed that TSs do not infiltrate into the CS or subdural space. Dolenc \u003cem\u003eet al.\u003c/em\u003e\u003csup\u003e[16]\u003c/sup\u003e found that TSs were located in the inter-dural space. Yoshida \u003cem\u003eet al\u003c/em\u003e. observed that TSs were covered with the inner layer\u003csup\u003e[32]\u003c/sup\u003e, indicating that most M-type TSs arose from the lateral wall of the CS or Meckel\u0026rsquo;s cave lesions.\u003csup\u003e[10]\u003c/sup\u003e. Chen \u003cem\u003eet al.\u003c/em\u003e\u003csup\u003e[21]\u003c/sup\u003e did not observe CS invasion in 55 patients. However, Samii \u003cem\u003eet al.\u003c/em\u003e\u003csup\u003e[18]\u003c/sup\u003e found 1 case with TS invading the CS.\u003c/p\u003e\n\u003cp\u003eIn current study, we obtained different results. We retrospectively analyzed data from 78 patients with TSs whose tumors occupied the MCF, and detected that tumors invading the CS in 13 cases(16.7%). Then, we compared the clinical features and tumor characteristics of the two groups and found that there were higher incidences of diplopia, larger tumor diameter in the MCF and lower GTR when TSs invaded the CS. There was no statistically significant difference in gender, age, classification, nature, width of channel, and other clinical symptoms. It was considered that the abducent nerve was encased when TS invaded the CS, resulting in diplopia. Surprisingly, the classification and the width of the communicating channel did not show a statistically significant difference between these two groups, indicating that the reason of the CS breakthrough is invasion of the lateral wall rather than compression.\u003c/p\u003e\n\u003cp\u003eThere were 2 cases of 15 cases with radiographic suspicion but no true invasion. ICA was encased by the tumor, but the thin inner membranous layer was intact during the surgery. Tumor sizes in the MCF were 23 mm and 25 mm, and the tumors did not cause diplopia.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDue to the effectiveness of radiotherapy, conservative treatment of the tumor\u0026nbsp;in\u0026nbsp;the\u0026nbsp;CS\u0026nbsp;is recommended, which also\u0026nbsp;reduces\u0026nbsp;morbidity\u0026nbsp;without sacrificing tumor control\u003csup\u003e[33]\u003c/sup\u003e. However, Surgical strategies should help maximize tumor resection while minimizing the morbidity of these large tumors. Only this will reduce postoperative recurrence. The CS is more likely to be opened to remove the intracavernous tumor if the tumor is expected to be soft. Because of their delicate nature, these tumors are easily sucked out and separated from the intracavernous ICA and cranial nerves.\u003csup\u003e[34]\u003c/sup\u003e Even when the tumor is tough and difficult to remove, the \u0026quot;natural\u0026quot; corridor to the CS provided by the tumor can help its complete resection with CUSA. However, it may be difficult to dissect the tumor without neurovascular injury.\u0026nbsp;During dissection in 1 case, the ICA ruptured due to the tough nature of the tumor and its tight adhesion to the ICA. A vascular suture was employed after temporary occlusion, and the tumor was completely removed (\u003cstrong\u003eFigure 3\u003c/strong\u003e). Therefore, it is critical to preoperatively assess the relationship between the tumor and ICA and measure the texture of the tumor. For tumors with CS invasion, the transcranial approach appears to be superior to EEA because it allows possible suturing of the ruptured artery.\u003c/p\u003e\n\u003cp\u003eAlthough it has been rarely reported that TS can invade the lateral wall of the CS, we believe that the phenomenon is not rare. This type of TSs may be more invasive than others. No reliable radiological method can accurately evaluate whether a tumor invaded the CS, which can be the potential reason for lower GTR. Based on our experience, some clues may best predict true CS invasion, such as the clinical symptom of diplopia, a larger diameter of the tumor in the MCF, the incomplete lateral wall of the CS, and the tumor beyond the ICA in preoperative radiological images. These data can help preoperative planning and protect the tissues and vascular structures.\u003c/p\u003e\n\u003cp\u003eLimitation\u003c/p\u003e\n\u003cp\u003eThe molecular pathology of TSs with CS invasion needs further studies. High-resolution MRI with thin slice scan and high-definition 3D modeling on radiological images will be beneficial for an accurate preoperative evaluation, although further studies are still needed.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eSeventy-eight patients with TSs occupying the MCF were surgically treated. TSs can invade the CS, which can lower GTR. Some clues may help predict the CS invasion, such as the clinical symptom of diplopia, the large diameter of the tumor in the MCF, and tumor invasion beyond the ICA in radiographic images. A thorough preoperative evaluation can be helpful.\u0026nbsp;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgement\u003c/strong\u003e The authors sincerely thank all colleagues of the neurosurgery department in Tiantan Hospital.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e Yu Zhang, Heng Zhang, Jie Yin were jointly responsible for the analysis of the data and writing of the paper. Zhe Zhang participated in the linguistic polishing of the manuscript. Minjun Yan and Yihao Wu helped search the literature, while Zhijun Yang was responsible for data collation. Pinan Liu was responsible for reviewing improvements and financial support.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003eNo funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e The analyzed data sets generated during the present study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompliance with ethical standards\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e The authors declare that they have no conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval\u0026nbsp;\u003c/strong\u003eAll procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional review boards at both institutions and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed consent\u0026nbsp;\u003c/strong\u003eInformed consent was obtained from all individual participants included in the study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eWanibuchi M, Fukushima T, Zomordi AR, Nonaka Y, Friedman AH (2012) Trigeminal schwannomas: skull base approaches and operative results in 105 patients. Neurosurgery. 70(1 Suppl Operative): 132\u0026thinsp;\u0026ndash;\u0026thinsp;43; discussion 143-4.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJoo W, Yoshioka F, Funaki T, Mizokami K, Rhoton AL Jr (2014) Microsurgical anatomy of the trigeminal nerve. Clin Anat 27(1):61\u0026ndash;88\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang X, Bao Y, Chen G et al (2019) Trigeminal Schwannomas in Middle Fossa Could Breach into Subdural Space: Report of 4 Cases and Review of Literature. World Neurosurg 127:e534\u0026ndash;e541\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJEFFERSON G (1953) The trigeminal neurinomas with some remarks on malignant invasion of the gasserian ganglion. Clin Neurosurg 1:11\u0026ndash;54\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSamii M, Migliori MM, Tatagiba M, Babu R (1995) Surgical treatment of trigeminal schwannomas. J Neurosurg 82(5):711\u0026ndash;718\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRamina R, Mattei TA, S\u0026oacute;ria MG et al (2008) Surgical management of trigeminal schwannomas. Neurosurg Focus 25(6):E6 discussion E6\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYoshida K, Kawase T (1999) Trigeminal neurinomas extending into multiple fossae: surgical methods and review of the literature. J Neurosurg 91(2):202\u0026ndash;211\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGoel A, Shah A, Muzumdar D, Nadkarni T, Chagla A (2010) Trigeminal neurinomas with extracranial extension: analysis of 28 surgically treated cases. J Neurosurg 113(5):1079\u0026ndash;1084\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGoel A (2023) Letter to the Editor. Trigeminal schwannomas. 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Otol Neurotol 39(1):82\u0026ndash;91\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Trigeminal Schwannoma, Cavernous Sinus, Invasion, Radiological images, Diplopia, Classification, Surgical approach","lastPublishedDoi":"10.21203/rs.3.rs-3983967/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3983967/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study reports trigeminal schwannomas (TSs) in 13 cases whose cancer invaded the cavernous sinus (CS) in the middle cranial fossa (MCF). Seventy-eight patients who underwent surgical treatment in Beijing Tiantan Hospital in the last 6 years were retrospectively analyzed and a literature review was conducted. The patients were divided into 2 groups by definitive evidence of CS invasion during surgery. Group A included 65 cases. Six patients suffered from diplopia. Tumor size in their MCF ranged from 7 mm to 48 mm (mean: 23.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.0 mm), and the gross total resection(GTR) was 93.8%. Group B included 13 cases, among whom 5 developed diplopia (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Tumor size in their MCF ranged from 17 mm to 44 mm (mean: 30.0\u0026thinsp;\u0026plusmn;\u0026thinsp;7.7 mm) (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), and the GTR was 69.2% (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In patients with CS invasion, there was a higher incidence of diplopia and larger tumor diameter. Gender, age, classification, nature, width of channel, and other clinical symptoms did not show statistical significance. So the TSs can invade CS, which can lower GTR. Some features may help predict the invasion, and a thorough preoperative assessment is helpful.\u003c/p\u003e","manuscriptTitle":"Can Trigeminal Schwannomas in Middle Cranial Fossa Invade Cavernous Sinus","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-05 18:33:44","doi":"10.21203/rs.3.rs-3983967/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a08064ef-6beb-4df7-9c7d-0d9b7d81f948","owner":[],"postedDate":"March 5th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-03-13T23:14:32+00:00","versionOfRecord":[],"versionCreatedAt":"2024-03-05 18:33:44","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3983967","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3983967","identity":"rs-3983967","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}