Appropriate method of opening and closing the dura during endonasal transsphenoidal surgery: A technical report focusing on dural incision designs that considers dural tenting and dural suturing

Appropriate method of opening and closing the dura during endonasal transsphenoidal surgery: A technical report focusing on dural incision designs that considers dural tenting and dural suturing | 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 Method Article Appropriate method of opening and closing the dura during endonasal transsphenoidal surgery: A technical report focusing on dural incision designs that considers dural tenting and dural suturing Kosaku Amano, Yuichi Oda, Takakazu Kawamata This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4009396/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 Here, we aimed to present an effective dural incision design that considers subsequent dural tenting and suturing in endonasal transsphenoidal surgery (TSS). In 2011, we discontinued the conventional cruciate dural incision and changed the dural incision design to create a sufficiently large dural window and the shortest incision line to reduce the interdural gap after dural suturing simultaneously. Considering the type, size, direction of extension, uneven distribution, and anticipated resection degree of the tumour, we explored dural incisions of different shapes, including horizontal and vertical straight, T-, Y-, U-, and H-shaped ones. The large dural flaps were tented using 6 − 0 nylon. The edges of the dural flaps were gathered and routinely sutured at the end of the surgery to prevent cerebrospinal fluid leakage. The modified H-shaped incision design empirically reduced the interdural gap. Planar geometrical analysis showed that this was an appropriate dural incision design because it had the shortest incision line. Moreover, Y with an upside-down T-shaped incision was suitable for extended TSS, and sideways Y-shaped and straight incisions were suitable for cases in which a large window was unnecessary. The modified H-shaped dural incision is an optimal choice for effective dural flap tenting and suturing and should be routinely used in TSS. transsphenoidal surgery dural incision design dural tenting dural suturing interdural gap CSF leakage Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Transsphenoidal surgery (TSS) is a standard surgical technique for the resection of pituitary and parasellar tumours. The introduction of endoscopes, development of dedicated instruments [ 4 , 24 , 25 ], advancements in extended TSS [ 6 , 7 , 9 , 11 , 15 ], utilisation of high-definition and indocyanine green endoscopes [ 2 ], and progress in preventing complications [ 22 ], especially cerebrospinal fluid (CSF) leakage [ 3 , 5 , 8 , 10 , 12 , 13 , 21 ], have enabled more aggressive tumour resection. However, the dural incision method has been used for the cruciate incision since the Hardy’s era [ 18 ]. Nevertheless, in contrast to transcranial surgery (TCS), the working chamber at TSS is extremely narrow and deep and manoeuvres are restricted [ 4 ], and CSF leakage is more likely to occur in TSS and can be a serious life-threatening problem. Direct suturing of the dura is a routine procedure and the ultimate method for achieving watertight closure in TCS, and it should be the same in TSS. Therefore, determining an appropriate method of opening and closing the dura is more important in TSS than in TCS. We aimed to propose an appropriate method for dural opening and closing at TSS to optimise the surgical procedure, help surgeons improve the effectiveness of the approach, work with easier and better movements, shorten surgical time, save effort, and effectively prevent CSF leakage. Materials and Methods Since 1998, we have introduced an endoscope to perform TSS. Initially, we used a cruciate incision to open the dura; tented the dural flaps using 6 − 0 nylon at four points, which were fastened out of the nostril to avoid interfering with tumour resection; and routinely sutured the dura for closure at the end of TSS (Fig. 1 a). However, in 2011, we discontinued the cruciate dural incision and began exploring dural incision designs that would provide a larger opening window, more effective dural tenting, and a smaller interdural gap when the dural flap edges were pulled to each other and sutured. Considering the type, size, direction of extension, uneven distribution, and anticipated resection degree of the tumour, we tried various shapes of dural incision, such as horizontal and vertical straight and T-, Y-, U- (Fig. 1 b), and H-shaped (Fig. 1 c). The large dural flap was tented using a 6 − 0 monofilament and fastened out of the nostril to avoid interference with tumour resection. At the end of the surgery, we gathered and sutured the dural flap edges. Furthermore, we attempted to reduce the number of tenting and stitches to make a larger working space and save time and effort. This study was approved by the Human Investigation Committee of Tokyo Women’s Medical University (approval number: 2021-0063) and was conducted in accordance with the tenets of the Declaration of Helsinki. Informed consent was obtained from all patients or their families. Results After practical substantiation of various dural incisions (Fig. 1 b), we observed empirically that the H-shaped incision of the sella dura (Fig. 1 c) facilitated easier gathering of the dural flaps and resulted in a smaller interdural gap when the flaps were sutured. This incision design was suitable for typical midline pituitary adenomas, sideways Y-shaped incisions for unevenly distributed microadenomas, Y-shaped with upside-down T-shaped incisions for craniopharyngiomas, and straight incisions for Rathke’s cleft cysts. Moreover, we made modifications to the H-shaped dural incision (Fig. 1 c) as follows: vertical lines on both sides were obliquely deviated bilaterally to further reduce the interdural gap and resect the tumour in the cavernous sinus in an easier way (Fig. 1 d). Furthermore, we shifted the horizontal line further downward to ensure a single suspended thread, resulting in the modified H-shaped dural incision (Fig. 1 e). Figure 3 demonstrates the cruciate incision and modified H-shaped incision adapted for planar geometrical analysis of incision design, which was reported by Nagai et al. in 2013 [ 19 ]. The length of dural incision lines was 36.06 and 32.32 cm (supposing a 10 × 15-cm dural window), and there were large interdural gaps and almost no gaps, respectively (Fig. 2 ). Case presentation 1: Midline macroadenoma Case presentation 1 involved a 42-year-old man with a nonfunctioning pituitary adenoma. The dura was incised in a modified H shape. The incision sequence was horizontal line, upper diagonal lines, and lower diagonal lines. The horizontal incision was shifted downward, and only the upper dural flap was tented. The intrasellar tumour was resected under a 0° endoscopic view, and the suprasellar tumour was resected with a look-up under a 45° endoscopic view. The dural flaps did not interfere with the procedures for either intra- or suprasellar lesions, resulting in complete tumour resection (Fig. 3 ). Case presentation 2: Craniopharyngioma A 23-year-old woman with craniopharyngioma underwent extended TSS. The dura of the sella and planum sphenoidale was incised in a Y shape, with an upside-down T shape. The incision sequence was (1) vertical line (cutting upward while stopping bleeding from the intercavernous sinus until reaching the optic chiasm), (2) upper diagonal lines (at the upper edge of the chiasm and bilateral optic nerves), and (3) lower horizontal line (at the upper edge of the normal pituitary gland). The bilateral dural flaps were tented using threads fastened out of the respective bilateral nostrils. The intrasellar and suprasellar tumours were resected under a 0° and a 30° or 45° endoscopic view, respectively. The dural flaps did not interfere with the procedures for both the intrasellar or suprasellar lesions. The dural flaps were closed watertight using fat with three stitches (Fig. 4 ). Case presentation 3: Microadenoma existing unevenly on the right side Case presentation 3 involved a 36-year-old woman with a growth hormone-producing adenoma. The dura was incised in Y-shape sideways. The right upper dural flap was then tented. The tumour was completely resected under a 30° or 45° endoscopic view. The dural flaps did not interfere with the intrasellar procedure (Fig. 5 a–d). Case presentation 4: Rathke’s cleft cyst Case presentation 4 involved a 26-year-old woman with Rathke’s cleft cyst. The dura was incised as a horizontal straight incision at the bottom of the sellar floor, where the normal gland became thin, to not injure the normal gland located in front of the cyst. The cyst contents and wall were adequately resected using this minimal incision (Fig. 5 e–h). When comparing 600 cases subjected to cruciate dural incision before 2011 with 600 cases after discontinuing the incision, there was no significant increase in the incidence of CSF leakage (2%: 12/600 vs. 0.5%: 3/600; p = 0.019). Discussion Similar to TCS, the larger the opening of the dura, the easier it is to resect the tumour, and the shorter the dura incision, the easier it is to close the dura in TSS. However, only a few reports have described the dural incision method even for TCS [ 28 , 29 , 30 ]. In this study, we focused on the important challenge in TSS: determining an appropriate method of opening and closing the dura. We should consider the following when performing TSS: (1) how to widely open the dura, (2) how to deal with dural flaps during tumour resection; and (3) how to close the dura with a smaller interdural gap. These procedures are closely related in TSS. The conventional cruciate dural incision in TSS has a long history since the Hardy’s era, and we inherited it without doubt from our mentors. In fact, in this old-fashioned dural incision, the open window was not remarkably large, four dural flaps interfered with intradural visibility and procedures, and it was difficult to gather and suture the edges of the dural flaps with a small interdural gap. However, the introduction of a high-definition endoscope and progress in extended TSS have enabled aggressive tumour resection and drastically changed the quality of TSS. Consequently, these innovations have led to the consideration of how to open and close the dura in TSS more effectively. This is a major issue in TSS because of its restricted working chamber, deep and narrow surgical corridor, and CSF leakage probability. Generally, to ensure sufficient tumour resection in TCS, a large surgical field should be created by opening the dura widely. However, the dura of the pituitary and parasellar regions is remarkably small, and it is surrounded by important structures that do not widely open in TSS. Additionally, CSF leakage seldom occurs after TSC. However, CSF leakage commonly occurs and can be a constant potential problem that may result in serious sequelae after TSS. Therefore, we developed various dural incisions and considered the appropriate fashion to close the dura to prevent CSF leakage in TSS. Hence, we sought a more effective dural incision design that would provide a wider opening area and concurrently enable a smaller interdural gap when the dural flap edges were pulled out and sutured, similar to the shorter dural incision line. How to open the sella dura considering incision designs After gaining practical experience, we realised that an empirically H-shaped dural incision was logical in 2011 (Fig. 1 c). The vertical lines on both sides deviated obliquely bilaterally, making the interdural gap even smaller and making it easier to resect the tumour in the cavernous sinus (Fig. 1 d). However, both the upper and lower dural flaps required tenting in this incision; thus, the horizontal line was shifted downward to allow tenting of only the upper dural flap (Fig. 1 e). We considered this modified H-shaped dural incision to be the optimal design for regular use in TSS. Subsequently, Nagai et al. reported a planar geometrical analysis for dural incision designs in 2013 and theoretically proved that a modified H-shaped dural incision in TSS was the correct method. This modified H-shaped dural incision line shortened the length of incision at 10.4% (36.06–32.32 cm, Fig. 2 a, b) compared to the conventional cruciate dural incision using their geometrical analysis [ 18 ]. It enabled tumour resection without dural flaps interference; made dural suturing of the sella closure significantly easier, certain, and requiring less effort; and made the interdural gap smaller by only three stiches (Fig. 2 d). In cases of extended TSS required for craniopharyngioma, the Y-shaped incision with an upside-down T-shaped incision was better than the modified H-shaped incision. By vertically cutting the dura and tenting the bilateral dural flaps, we were able to control the bleeding from the intercavernous sinus and create a sufficiently large window, and by cutting the vertical line upward, we were able to assess the location of the chiasm. Finally, we closed the dura watertight with fat sufficiently using three stitches (Fig. 4 ). In cases of microadenoma, Rathke’s cleft cyst, and biopsy [ 33 ], we do not need a large dural window, and a minimal incision is sufficient (Fig. 5 ). How to close the dura considering the significance of dural suturing Suturing of the dura in TCS is a simple, practical, and common method performed at the end of surgery and is the most reliable and ideal means for primary closure of a fistula. Similar to that in TCS, suturing of the dura is the ultimate method for achieving closure of the sellar turcia in TSS and must be performed as a routine procedure. As suturing of the sella dura in TSS has been performed routinely at our facility since 1998, we were unable to directly demonstrate the efficacy of dural suturing in TSS. However, several reports have shown a reduction in the CSF leakage rate resulting from dural sutures in TSS. This technique is not a stand-alone method for sella reconstruction but would be an effective means in TSS for complete repair of a small to large fistula to help prevent CSF leakage [ 1 , 14 , 17 , 20 , 26 , 31 , 32 , 34 , 35 , 36 ]. In TSS, we routinely placed at least one (maximum three) stitch between the counterpart corners of the dural flaps, even in cases with minor or no CSF leakage. The purposes of dural suturing are as follows: (1) reducing the ‘gap’ of dural defects and facilitating dura regeneration; (2) maintaining sufficient tension in the dura to resist CSF pulsatile pressure; (3) supporting the intra–extrasellar graft to prevent migration; and (4) facilitating water-tight closure, if necessary [ 4 ]. Although watertight closure was not achieved, narrowing of the dural defect, reduction of the interdural gap, maintenance of tension of the dura, and support of the intrasellar graft were achieved in all patients. If the dura was tightly sutured, autologous grafts were used only to ensure watertight closure when major CSF leakage developed (Fig. 4 ). Suturing the sella dura in TSS is one method to consider, which reduces the risk of CSF leakage and carries fewer disadvantages. However, owing to the restricted working chamber and the deep and narrow surgical corridor, achieving complete suturing of the dura in TSS is technically challenging, cumbersome, difficult, and time-consuming [ 4 ]. Therefore, a dural incision design with a shorter incision line must be considered to facilitate suturing. Other varied techniques for the repair and prevention of CSF leakage in TSS, such as a vascularised mucoseptal flap and sphenoid sinus mucosal flap, are reliable and simple methods for preventing CSF leakage [ 3 , 16 , 19 , 23 , 27 , 37 ]. However, they have limitations, and utilisation of a vascularised mucoseptal flap may not be possible in some situations, such as in recurrent cases with septal perforation, and is ineffective for all cases. Dural suturing techniques should be mastered by pituitary surgeons to prevent potential CSF leakage, and an effective dural incision is necessary to achieve this procedure. Significance of dural tenting During surgical procedures for the intra-suprasellar region, such as dissection and resection of the tumour, the dura mater itself becomes a fluttering flap, obstructs vision, and interferes with the procedures. Hence, we routinely tented the dural flap using 6 − 0 nylon and fastened it out of the nostril during tumour resection. The purposes of dural tenting were as follows: (1) opening the dural window widely for good visibility of the intra-suprasellar region, (2) avoiding fluttering of the dural flap from interfering with the procedure, and (3) becoming a landmark when inserting an angled endoscope and resecting a tumour. The effectiveness of purposes 1 and 2 was the same as that of TCR, and we tried to do the same in TSS as in TCR, but that of purpose 3 was specific to endoscopic TSS. The smooth insertion of angled endoscopes (45° and 70°) from the nostril into the sella turcia was difficult, but following a thread connected to the sella dura made it easy and quick. When resecting a tumour in the cavernous sinus using an angled endoscope, a thread provides spatial awareness in four directions: up, down, left, and right. In addition, identifying anatomical structures becomes challenging in a pool of blood following an internal carotid artery injury. A tented thread helped us obtain an in-depth understanding of the anatomy, and we could suck a massive amount of blood and stop the bleeding without panic. We need more special and additional considerations for dural opening, tenting, and closing in TSS than in TCS, and these ingenuities facilitate manoeuvrability in TSS and make TSS a safe and secure surgery. Conclusions Determining an appropriate method of opening and closing the dura is crucial in TSS. Therefore, we propose the routine use of a modified H-shaped dural incision with the shortest cutting length, considering the planar geometry. This incision design enables tumour resection with a single tented dural flap without interference with intra-suprasellar visibility and procedures and resulted in a smaller interdural gap after suturing the sella dura in TSS. In addition, we observed better changes in the incision design at the extended TSS and in cases with minimal incisions. Declarations Acknowledgements The authors thank Dr. Atsushi Fukui for statistical analysis. Code availability Not applicable. Funding This work was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (Grant No. JP21K09139). Disclosure of potential conflicts of interest The authors have no relevant financial or non-financial interests to disclose. Author contribution Conceptualisation: Kosaku Amano. Writing—original draft preparation, review and editing: Kosaku Amano. Funding acquisition: Kosaku Amano. Resources: Kosaku Amano, Yuichi Oda. Supervision: Takakazu Kawamata. Research involving Human Participants Ethics approval This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the ethics committee of the Tokyo Women’s Medical University (approval number: 2021-0063). Informed consent Consent to participate Given the retrospective design, the institutional review board waived the requirement for obtaining informed consent from the patients. We used the opt-out method. To protect patient privacy, we removed all identifiers from our records upon completion of our analyses. Consent for publication Not applicable. Data availability The datasets during and/or analysed during the current study are available from the corresponding author on reasonable request. References Ahn JY, Kim SH (2009) A new technique for dural suturing with fascia graft for cerebrospinal fluid leakage in transsphenoidal surgery. Neurosurgery 65:65-71; discussion 71. https://doi.org/10.1227/01.NEU.0000327695.32775.BB Amano K, Aihara Y, Tsuzuki S, Okada Y, Kawamata T (2019) Application of indocyanine green fluorescence endoscopic system in transsphenoidal surgery for pituitary tumors. 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Acta Neurochir (Wien) 157:2089-2092. https://doi.org/10.1007/s00701-015-2612-4 Thorp BD, Sreenath SB, Ebert CS, Zanation AM (2014) Endoscopic skull base reconstruction: a review and clinical case series of 152 vascularized flaps used for surgical skull base defects in the setting of intraoperative cerebrospinal fluid leak. Neurosurg Focus 37:E4. https://doi.org/10.3171/2014.7.FOCUS14350 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. 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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-4009396","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Method Article","associatedPublications":[],"authors":[{"id":276333630,"identity":"243c9d63-c55e-410f-9a25-c1d4fdc8fa00","order_by":0,"name":"Kosaku Amano","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwUlEQVRIiWNgGAWjYBACCQhlAxdgJlZLmgTJWg5L4FeGDCTbTyd+Lqg4X2dw7YwBw48aBnZzQlqkeXI3S884c1vC4HaOAWPPMQZmywYCWuQYcjdI87bdljADamHgbWBgNjhASAv/282/edvOgbUw/iVGi7RE7jagLQfAWpiJskVyxttt1jxnkiX3304rOCxzTIKwXyTO526+zVNhxy85O3njwzc1NskEQwwFAJ0kkWxAkhYQsCNdyygYBaNgFAx3AACF/zmu92PjxQAAAABJRU5ErkJggg==","orcid":"","institution":"","correspondingAuthor":true,"prefix":"","firstName":"Kosaku","middleName":"","lastName":"Amano","suffix":""},{"id":276333631,"identity":"a316a09a-a61b-4079-b8c7-11b13d9e32b8","order_by":1,"name":"Yuichi Oda","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Yuichi","middleName":"","lastName":"Oda","suffix":""},{"id":276333632,"identity":"44bfd64e-e3e9-46b3-a515-db47665f1dfb","order_by":2,"name":"Takakazu Kawamata","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Takakazu","middleName":"","lastName":"Kawamata","suffix":""}],"badges":[],"createdAt":"2024-03-03 18:07:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4009396/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4009396/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":52193869,"identity":"428e223b-b64b-44f1-a1f3-9a9c5ad51164","added_by":"auto","created_at":"2024-03-07 19:39:35","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":292152,"visible":true,"origin":"","legend":"\u003cp\u003e(a) \u003ca href=\"https://eow.alc.co.jp/search?q=schematic\u0026amp;ref=awlj\"\u003eSchematic\u003c/a\u003e \u003ca href=\"https://eow.alc.co.jp/search?q=diagram\u0026amp;ref=awlj\"\u003ediagram\u003c/a\u003es showing the old-type cruciate dural incision. Four dural flaps are individually tented using 6-0 nylons. (b) \u003ca href=\"https://eow.alc.co.jp/search?q=schematic\u0026amp;ref=awlj\"\u003eSchematic\u003c/a\u003e \u003ca href=\"https://eow.alc.co.jp/search?q=diagram\u0026amp;ref=awlj\"\u003ediagram\u003c/a\u003es showing various shapes of dural incisions that we tried. (c) H-shaped dural incision, which had an empirically small interdural gap after dural suturing. (d) H-shaped dural incision with vertical lines on both sides obliquely deviates bilaterally. (e) Modified H-shaped dural incision, with the horizontal line shifting downward to separate the tented flap\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4009396/v1/1d5cc223a82842152d709a28.jpg"},{"id":52193868,"identity":"b2faffd0-b44f-41c7-ab0c-6b86178324ed","added_by":"auto","created_at":"2024-03-07 19:39:35","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":276733,"visible":true,"origin":"","legend":"\u003cp\u003eComparing dural incisions between (a) cruciate dural incision and (b) modified H-shaped dural incision; the length of the incision lines was 36.06 and 32.32 cm, respectively, if the dural field was assumed as 10 cm × 15 cm. Intraoperative view after suturing the dura demonstrating (c) a large interdural gap and (d) no interdural gap. Black cross mark: suture using tenting thread; white cross mark: additional suture at both corners of the dural flaps\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4009396/v1/680fa634abe648871b8948be.jpg"},{"id":52193870,"identity":"897ca0c8-e7f7-4446-87b1-ed18912bc35c","added_by":"auto","created_at":"2024-03-07 19:39:35","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":336731,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Coronal T1-weighted magnetic resonance imaging (MRI) with gadolinium (Gd) enhancement reveals a pituitary adenoma. (b) Modified H-shaped dural incision. (c) Dural window and a tented flap. (d) Sagittal T1-weighted MRI with Gd demonstrating the positional relationship among 0° endoscope, dural flap with nylon, and viewing direction (white allow) to intrasellar tumour. (e) Sagittal T1-weighted MRI with Gd demonstrating the positional relationship among 30° or 45° endoscope, dural flap with nylon, and viewing direction (white allow) to suprasellar tumour. (f) A 45° endoscopic view in the upward direction of the tumour bed\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4009396/v1/36faf7148b6760678a76171e.jpg"},{"id":52193867,"identity":"26e1b49c-f7eb-45c6-9131-ed76a5bed26e","added_by":"auto","created_at":"2024-03-07 19:39:35","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":499536,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Coronal T1-weighted magnetic resonance imaging (MRI) with gadolinium (Gd) enhancement reveals a craniopharyngioma. (b) Sagittal T1-weighted MRI with Gd. (c) The \u003ca href=\"https://eow.alc.co.jp/search?q=schematic\u0026amp;ref=awlj\"\u003eschematic\u003c/a\u003e \u003ca href=\"https://eow.alc.co.jp/search?q=diagram\u0026amp;ref=awlj\"\u003ediagram\u003c/a\u003es demonstrating Y and reverse T-shaped dural incision. (d) Dural window and two tented flaps. (e) A 0° endoscopic view of pre-tumour resection. (f) A 0° endoscopic view of post-tumour resection. (g) A 30° endoscopic view of water-tight dural closure with fat\u003c/p\u003e","description":"","filename":"Figure4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4009396/v1/1b38188d6e250ae83116be61.jpg"},{"id":52193871,"identity":"a2d042cc-993a-43df-9424-160e462769af","added_by":"auto","created_at":"2024-03-07 19:39:35","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":485729,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Coronal T1-weighted magnetic resonance imaging (MRI) with gadolinium (Gd) enhancement reveals a growth hormone-producing pituitary adenoma demonstrating the positional relationship between the 30° endoscope and viewing direction (white allow) to the intrasellar tumour. (b) The \u003ca href=\"https://eow.alc.co.jp/search?q=schematic\u0026amp;ref=awlj\"\u003eschematic\u003c/a\u003e \u003ca href=\"https://eow.alc.co.jp/search?q=diagram\u0026amp;ref=awlj\"\u003ediagram\u003c/a\u003es demonstrate sideways Y-shaped dural incision. (c) A 30° endoscopic view of tumour resection. (d) A 30° endoscopic view of the tumour bed. (e) Coronal T1-weighted MRI with Gd enhancement reveals a Rathke’s cleft cyst demonstrating the positional relationship among a 30° or 45° endoscope, dural incision, viewing direction (white allow) to the bottom of the cyst, and normal gland (white triangle). (f) Horizontal straight dural incision at the bottom of the sella floor. (g) A 30° endoscopic view of cyst content resection. (h) A 45° endoscopic view of cyst wall resection\u003c/p\u003e","description":"","filename":"Figure5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4009396/v1/0d9c2d729c5954eaae5814cd.jpg"},{"id":52461113,"identity":"fe50f365-c57b-48c5-9998-a9a90a97b066","added_by":"auto","created_at":"2024-03-11 23:07:52","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":865941,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4009396/v1/6bc2a43e-bd7c-468c-95fe-42d4d8f4a0c5.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Appropriate method of opening and closing the dura during endonasal transsphenoidal surgery: A technical report focusing on dural incision designs that considers dural tenting and dural suturing","fulltext":[{"header":"Introduction","content":"\u003cp\u003eTranssphenoidal surgery (TSS) is a standard surgical technique for the resection of pituitary and parasellar tumours. The introduction of endoscopes, development of dedicated instruments [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], advancements in extended TSS [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], utilisation of high-definition and indocyanine green endoscopes [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], and progress in preventing complications [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], especially cerebrospinal fluid (CSF) leakage [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], have enabled more aggressive tumour resection. However, the dural incision method has been used for the cruciate incision since the Hardy\u0026rsquo;s era [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Nevertheless, in contrast to transcranial surgery (TCS), the working chamber at TSS is extremely narrow and deep and manoeuvres are restricted [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], and CSF leakage is more likely to occur in TSS and can be a serious life-threatening problem. Direct suturing of the dura is a routine procedure and the ultimate method for achieving watertight closure in TCS, and it should be the same in TSS. Therefore, determining an appropriate method of opening and closing the dura is more important in TSS than in TCS. We aimed to propose an appropriate method for dural opening and closing at TSS to optimise the surgical procedure, help surgeons improve the effectiveness of the approach, work with easier and better movements, shorten surgical time, save effort, and effectively prevent CSF leakage.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eSince 1998, we have introduced an endoscope to perform TSS. Initially, we used a cruciate incision to open the dura; tented the dural flaps using 6\u0026thinsp;\u0026minus;\u0026thinsp;0 nylon at four points, which were fastened out of the nostril to avoid interfering with tumour resection; and routinely sutured the dura for closure at the end of TSS (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). However, in 2011, we discontinued the cruciate dural incision and began exploring dural incision designs that would provide a larger opening window, more effective dural tenting, and a smaller interdural gap when the dural flap edges were pulled to each other and sutured. Considering the type, size, direction of extension, uneven distribution, and anticipated resection degree of the tumour, we tried various shapes of dural incision, such as horizontal and vertical straight and T-, Y-, U- (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb), and H-shaped (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). The large dural flap was tented using a 6\u0026thinsp;\u0026minus;\u0026thinsp;0 monofilament and fastened out of the nostril to avoid interference with tumour resection. At the end of the surgery, we gathered and sutured the dural flap edges. Furthermore, we attempted to reduce the number of tenting and stitches to make a larger working space and save time and effort.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThis study was approved by the Human Investigation Committee of Tokyo Women\u0026rsquo;s Medical University (approval number: 2021-0063) and was conducted in accordance with the tenets of the Declaration of Helsinki. Informed consent was obtained from all patients or their families.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eAfter practical substantiation of various dural incisions (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb), we observed empirically that the H-shaped incision of the sella dura (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec) facilitated easier gathering of the dural flaps and resulted in a smaller interdural gap when the flaps were sutured. This incision design was suitable for typical midline pituitary adenomas, sideways Y-shaped incisions for unevenly distributed microadenomas, Y-shaped with upside-down T-shaped incisions for craniopharyngiomas, and straight incisions for Rathke\u0026rsquo;s cleft cysts. Moreover, we made modifications to the H-shaped dural incision (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec) as follows: vertical lines on both sides were obliquely deviated bilaterally to further reduce the interdural gap and resect the tumour in the cavernous sinus in an easier way (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed). Furthermore, we shifted the horizontal line further downward to ensure a single suspended thread, resulting in the modified H-shaped dural incision (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee). Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e demonstrates the cruciate incision and modified H-shaped incision adapted for planar geometrical analysis of incision design, which was reported by Nagai et al. in 2013 [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The length of dural incision lines was 36.06 and 32.32 cm (supposing a 10 \u0026times; 15-cm dural window), and there were large interdural gaps and almost no gaps, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003eCase presentation 1: Midline macroadenoma\u003c/em\u003e \u003c/p\u003e \u003cp\u003eCase presentation 1 involved a 42-year-old man with a nonfunctioning pituitary adenoma. The dura was incised in a modified H shape. The incision sequence was horizontal line, upper diagonal lines, and lower diagonal lines. The horizontal incision was shifted downward, and only the upper dural flap was tented. The intrasellar tumour was resected under a 0\u0026deg; endoscopic view, and the suprasellar tumour was resected with a look-up under a 45\u0026deg; endoscopic view. The dural flaps did not interfere with the procedures for either intra- or suprasellar lesions, resulting in complete tumour resection (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cem\u003eCase presentation 2: Craniopharyngioma\u003c/em\u003e \u003c/p\u003e \u003cp\u003eA 23-year-old woman with craniopharyngioma underwent extended TSS. The dura of the sella and planum sphenoidale was incised in a Y shape, with an upside-down T shape. The incision sequence was (1) vertical line (cutting upward while stopping bleeding from the intercavernous sinus until reaching the optic chiasm), (2) upper diagonal lines (at the upper edge of the chiasm and bilateral optic nerves), and (3) lower horizontal line (at the upper edge of the normal pituitary gland). The bilateral dural flaps were tented using threads fastened out of the respective bilateral nostrils. The intrasellar and suprasellar tumours were resected under a 0\u0026deg; and a 30\u0026deg; or 45\u0026deg; endoscopic view, respectively. The dural flaps did not interfere with the procedures for both the intrasellar or suprasellar lesions. The dural flaps were closed watertight using fat with three stitches (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003eCase presentation 3: Microadenoma existing unevenly on the right side\u003c/em\u003e \u003c/p\u003e \u003cp\u003eCase presentation 3 involved a 36-year-old woman with a growth hormone-producing adenoma. The dura was incised in Y-shape sideways. The right upper dural flap was then tented. The tumour was completely resected under a 30\u0026deg; or 45\u0026deg; endoscopic view. The dural flaps did not interfere with the intrasellar procedure (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea\u0026ndash;d).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003eCase presentation 4: Rathke\u0026rsquo;s cleft cyst\u003c/em\u003e \u003c/p\u003e \u003cp\u003eCase presentation 4 involved a 26-year-old woman with Rathke\u0026rsquo;s cleft cyst. The dura was incised as a horizontal straight incision at the bottom of the sellar floor, where the normal gland became thin, to not injure the normal gland located in front of the cyst. The cyst contents and wall were adequately resected using this minimal incision (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ee\u0026ndash;h).\u003c/p\u003e \u003cp\u003eWhen comparing 600 cases subjected to cruciate dural incision before 2011 with 600 cases after discontinuing the incision, there was no significant increase in the incidence of CSF leakage (2%: 12/600 vs. 0.5%: 3/600; p\u0026thinsp;=\u0026thinsp;0.019).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eSimilar to TCS, the larger the opening of the dura, the easier it is to resect the tumour, and the shorter the dura incision, the easier it is to close the dura in TSS. However, only a few reports have described the dural incision method even for TCS [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. In this study, we focused on the important challenge in TSS: determining an appropriate method of opening and closing the dura. We should consider the following when performing TSS: (1) how to widely open the dura, (2) how to deal with dural flaps during tumour resection; and (3) how to close the dura with a smaller interdural gap. These procedures are closely related in TSS. The conventional cruciate dural incision in TSS has a long history since the Hardy\u0026rsquo;s era, and we inherited it without doubt from our mentors. In fact, in this old-fashioned dural incision, the open window was not remarkably large, four dural flaps interfered with intradural visibility and procedures, and it was difficult to gather and suture the edges of the dural flaps with a small interdural gap. However, the introduction of a high-definition endoscope and progress in extended TSS have enabled aggressive tumour resection and drastically changed the quality of TSS. Consequently, these innovations have led to the consideration of how to open and close the dura in TSS more effectively. This is a major issue in TSS because of its restricted working chamber, deep and narrow surgical corridor, and CSF leakage probability. Generally, to ensure sufficient tumour resection in TCS, a large surgical field should be created by opening the dura widely. However, the dura of the pituitary and parasellar regions is remarkably small, and it is surrounded by important structures that do not widely open in TSS. Additionally, CSF leakage seldom occurs after TSC. However, CSF leakage commonly occurs and can be a constant potential problem that may result in serious sequelae after TSS. Therefore, we developed various dural incisions and considered the appropriate fashion to close the dura to prevent CSF leakage in TSS. Hence, we sought a more effective dural incision design that would provide a wider opening area and concurrently enable a smaller interdural gap when the dural flap edges were pulled out and sutured, similar to the shorter dural incision line.\u003c/p\u003e \u003cp\u003e \u003cem\u003eHow to open the sella dura considering incision designs\u003c/em\u003e \u003c/p\u003e \u003cp\u003eAfter gaining practical experience, we realised that an empirically H-shaped dural incision was logical in 2011 (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). The vertical lines on both sides deviated obliquely bilaterally, making the interdural gap even smaller and making it easier to resect the tumour in the cavernous sinus (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed). However, both the upper and lower dural flaps required tenting in this incision; thus, the horizontal line was shifted downward to allow tenting of only the upper dural flap (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee). We considered this modified H-shaped dural incision to be the optimal design for regular use in TSS. Subsequently, Nagai et al. reported a planar geometrical analysis for dural incision designs in 2013 and theoretically proved that a modified H-shaped dural incision in TSS was the correct method. This modified H-shaped dural incision line shortened the length of incision at 10.4% (36.06\u0026ndash;32.32 cm, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, b) compared to the conventional cruciate dural incision using their geometrical analysis [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. It enabled tumour resection without dural flaps interference; made dural suturing of the sella closure significantly easier, certain, and requiring less effort; and made the interdural gap smaller by only three stiches (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed).\u003c/p\u003e \u003cp\u003eIn cases of extended TSS required for craniopharyngioma, the Y-shaped incision with an upside-down T-shaped incision was better than the modified H-shaped incision. By vertically cutting the dura and tenting the bilateral dural flaps, we were able to control the bleeding from the intercavernous sinus and create a sufficiently large window, and by cutting the vertical line upward, we were able to assess the location of the chiasm. Finally, we closed the dura watertight with fat sufficiently using three stitches (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). In cases of microadenoma, Rathke\u0026rsquo;s cleft cyst, and biopsy [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e], we do not need a large dural window, and a minimal incision is sufficient (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cem\u003eHow to close the dura considering the significance of dural suturing\u003c/em\u003e \u003c/p\u003e \u003cp\u003eSuturing of the dura in TCS is a simple, practical, and common method performed at the end of surgery and is the most reliable and ideal means for primary closure of a fistula. Similar to that in TCS, suturing of the dura is the ultimate method for achieving closure of the sellar turcia in TSS and must be performed as a routine procedure. As suturing of the sella dura in TSS has been performed routinely at our facility since 1998, we were unable to directly demonstrate the efficacy of dural suturing in TSS. However, several reports have shown a reduction in the CSF leakage rate resulting from dural sutures in TSS. This technique is not a stand-alone method for sella reconstruction but would be an effective means in TSS for complete repair of a small to large fistula to help prevent CSF leakage [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. In TSS, we routinely placed at least one (maximum three) stitch between the counterpart corners of the dural flaps, even in cases with minor or no CSF leakage. The purposes of dural suturing are as follows: (1) reducing the \u0026lsquo;gap\u0026rsquo; of dural defects and facilitating dura regeneration; (2) maintaining sufficient tension in the dura to resist CSF pulsatile pressure; (3) supporting the intra\u0026ndash;extrasellar graft to prevent migration; and (4) facilitating water-tight closure, if necessary [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Although watertight closure was not achieved, narrowing of the dural defect, reduction of the interdural gap, maintenance of tension of the dura, and support of the intrasellar graft were achieved in all patients. If the dura was tightly sutured, autologous grafts were used only to ensure watertight closure when major CSF leakage developed (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Suturing the sella dura in TSS is one method to consider, which reduces the risk of CSF leakage and carries fewer disadvantages. However, owing to the restricted working chamber and the deep and narrow surgical corridor, achieving complete suturing of the dura in TSS is technically challenging, cumbersome, difficult, and time-consuming [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Therefore, a dural incision design with a shorter incision line must be considered to facilitate suturing.\u003c/p\u003e \u003cp\u003eOther varied techniques for the repair and prevention of CSF leakage in TSS, such as a vascularised mucoseptal flap and sphenoid sinus mucosal flap, are reliable and simple methods for preventing CSF leakage [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. However, they have limitations, and utilisation of a vascularised mucoseptal flap may not be possible in some situations, such as in recurrent cases with septal perforation, and is ineffective for all cases. Dural suturing techniques should be mastered by pituitary surgeons to prevent potential CSF leakage, and an effective dural incision is necessary to achieve this procedure.\u003c/p\u003e \u003cp\u003e \u003cem\u003eSignificance of dural tenting\u003c/em\u003e \u003c/p\u003e \u003cp\u003eDuring surgical procedures for the intra-suprasellar region, such as dissection and resection of the tumour, the dura mater itself becomes a fluttering flap, obstructs vision, and interferes with the procedures. Hence, we routinely tented the dural flap using 6\u0026thinsp;\u0026minus;\u0026thinsp;0 nylon and fastened it out of the nostril during tumour resection. The purposes of dural tenting were as follows: (1) opening the dural window widely for good visibility of the intra-suprasellar region, (2) avoiding fluttering of the dural flap from interfering with the procedure, and (3) becoming a landmark when inserting an angled endoscope and resecting a tumour. The effectiveness of purposes 1 and 2 was the same as that of TCR, and we tried to do the same in TSS as in TCR, but that of purpose 3 was specific to endoscopic TSS. The smooth insertion of angled endoscopes (45\u0026deg; and 70\u0026deg;) from the nostril into the sella turcia was difficult, but following a thread connected to the sella dura made it easy and quick. When resecting a tumour in the cavernous sinus using an angled endoscope, a thread provides spatial awareness in four directions: up, down, left, and right. In addition, identifying anatomical structures becomes challenging in a pool of blood following an internal carotid artery injury. A tented thread helped us obtain an in-depth understanding of the anatomy, and we could suck a massive amount of blood and stop the bleeding without panic.\u003c/p\u003e \u003cp\u003eWe need more special and additional considerations for dural opening, tenting, and closing in TSS than in TCS, and these ingenuities facilitate manoeuvrability in TSS and make TSS a safe and secure surgery.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eDetermining an appropriate method of opening and closing the dura is crucial in TSS. Therefore, we propose the routine use of a modified H-shaped dural incision with the shortest cutting length, considering the planar geometry. This incision design enables tumour resection with a single tented dural flap without interference with intra-suprasellar visibility and procedures and resulted in a smaller interdural gap after suturing the sella dura in TSS. In addition, we observed better changes in the incision design at the extended TSS and in cases with minimal incisions.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e The authors thank Dr. Atsushi Fukui for statistical analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCode availability\u003c/strong\u003e Not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e This work was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (Grant No. JP21K09139).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eDisclosure of potential conflicts of interest\u003c/strong\u003e The authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eAuthor contribution\u003c/strong\u003e Conceptualisation: Kosaku Amano. Writing\u0026mdash;original draft preparation, review and editing: Kosaku Amano. Funding acquisition: Kosaku Amano. Resources: Kosaku Amano, Yuichi Oda. Supervision: Takakazu Kawamata.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eResearch involving Human Participants\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval\u0026nbsp;\u003c/strong\u003eThis study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the ethics committee\u0026nbsp;of the Tokyo Women\u0026rsquo;s Medical University (approval number: 2021-0063).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eInformed consent\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u003c/strong\u003e Given the retrospective design, the institutional review board waived the requirement for obtaining informed consent from the patients. We used the opt-out method. To protect patient privacy, we removed all identifiers from our records upon completion of our analyses.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e Not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eData availability\u0026nbsp;\u003c/strong\u003eThe datasets during and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAhn JY, Kim SH (2009) A new technique for dural suturing with fascia graft for cerebrospinal fluid leakage in transsphenoidal surgery. 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Acta Neurochir (Wien) 151:1427-1430. https://doi.org/10.1007/s00701-009-0406-2\u003c/li\u003e\n\u003cli\u003eOda Y, Amano K, Masui K, Kawamata T (2023) Clinical features of pituitary or parasellar tumor onset with cranial nerve palsy: surgical intervention considerations. World Neurosurg 175:e832-e840. https://doi.org/10.1016/j.wneu.2023.04.031\u003c/li\u003e\n\u003cli\u003eSuzuki S, Kobayashi E, Hododuka K, Amano K, Masamune K, Muragaki Y (2021) Development of a semiautomatic dura mater suturing device for preventing cerebrospinal fluid leakage in transsphenoidal surgery. Surg Innov 28:374-377. https://doi.org/10.1177/1553350620969000\u003c/li\u003e\n\u003cli\u003eTakeuchi K, Nagata Y, Tanahashi K, Saito R (2022) Quick and simple dural threading technique for transsphenoidal surgery - dural tenting, haemostasis and skull base reconstruction.\u003cem\u003e \u003c/em\u003eActa Neurochir (Wien) 164:1619-1622. https://doi.org/10.1007/s00701-022-05227-5\u003c/li\u003e\n\u003cli\u003eTakeuchi K, Nagatani T, Wakabayashi T (2015) How I do it: shoelace watertight dural closure in extended transsphenoidal surgery. Acta Neurochir (Wien) 157:2089-2092. https://doi.org/10.1007/s00701-015-2612-4\u003c/li\u003e\n\u003cli\u003eThorp BD, Sreenath SB, Ebert CS, Zanation AM (2014) Endoscopic skull base reconstruction: a review and clinical case series of 152 vascularized flaps used for surgical skull base defects in the setting of intraoperative cerebrospinal fluid leak. Neurosurg Focus 37:E4. https://doi.org/10.3171/2014.7.FOCUS14350\u003c/li\u003e\n\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":"transsphenoidal surgery, dural incision design, dural tenting, dural suturing, interdural gap, CSF leakage","lastPublishedDoi":"10.21203/rs.3.rs-4009396/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4009396/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eHere, we aimed to present an effective dural incision design that considers subsequent dural tenting and suturing in endonasal transsphenoidal surgery (TSS). In 2011, we discontinued the conventional cruciate dural incision and changed the dural incision design to create a sufficiently large dural window and the shortest incision line to reduce the interdural gap after dural suturing simultaneously. Considering the type, size, direction of extension, uneven distribution, and anticipated resection degree of the tumour, we explored dural incisions of different shapes, including horizontal and vertical straight, T-, Y-, U-, and H-shaped ones. The large dural flaps were tented using 6\u0026thinsp;\u0026minus;\u0026thinsp;0 nylon. The edges of the dural flaps were gathered and routinely sutured at the end of the surgery to prevent cerebrospinal fluid leakage. The modified H-shaped incision design empirically reduced the interdural gap. Planar geometrical analysis showed that this was an appropriate dural incision design because it had the shortest incision line. Moreover, Y with an upside-down T-shaped incision was suitable for extended TSS, and sideways Y-shaped and straight incisions were suitable for cases in which a large window was unnecessary. The modified H-shaped dural incision is an optimal choice for effective dural flap tenting and suturing and should be routinely used in TSS.\u003c/p\u003e","manuscriptTitle":"Appropriate method of opening and closing the dura during endonasal transsphenoidal surgery: A technical report focusing on dural incision designs that considers dural tenting and dural suturing","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-07 19:39:31","doi":"10.21203/rs.3.rs-4009396/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":"47c525e3-2173-4fa7-9ece-078e416bc550","owner":[],"postedDate":"March 7th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-03-11T22:59:45+00:00","versionOfRecord":[],"versionCreatedAt":"2024-03-07 19:39:31","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4009396","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4009396","identity":"rs-4009396","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}