Anterior and Middle Petrosectomy via an Extended Transorbital Neuroendoscopic Approach: Anatomic Study

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Lesions involving the petrous apex and cerebello-pontine angle (CPA) offer a formidable challenge via standard TONES approaches. This cadaveric study examined the surgical field-of-view and anatomic constraints provided by a novel extended transorbital neuroendoscopic ( e TONES) approach and compared these to previously described TONES approaches and the traditional subtemporal anterior petrosectomy. Methods The e TONES approach includes single-piece removal of the superior and lateral orbital rims. This in turn offers expanded surgical trajectory to middle fossa skull base, anterior petrous ridge, and ventro-lateral posterior fossa, while reducing globe retraction. Four cadaveric heads underwent e TONES approach on one side and traditional subtemporal anterior petrosectomy on the contralateral side. Petrosectomy volume, location, and posterior fossa field-of-view were compared between the two approaches. Results Mean volume of petrous bone removed in the standard e TONES was 0.84 ± 0.38 ml. In comparison, the mean volume of petrous bone removed in the subtemporal approach was 0.72 ± 0.15 ml. On a single specimen, a superior e TONES variation was performed, tailored to provide access to the petrous apex and petroclival region, and 0.07ml of petrous bone was removed. Standard e TONES offered a straight on ventral-to-dorsal view of the internal acoustic canal and CPA contents. Conversely, traditional subtemporal approach, provided an unobstructed view of the medial CPA and petroclival region, with a lateral-to-medial viewing angle. Superior e TONES variation ‘bridges-the-gap’ between standard e TONES and subtemporal approaches in terms of petroclival and petrous apex exposure. Conclusion e TONES provides a straight on, minimally invasive endoscopic surgical approach that is comparable to the traditional subtemporal approach and may complement other surgical approaches for lesions involving the cavernous sinus, petroclival region, petrous ridge, and CPA. The describ 1 ed approach has yet to be examined in a clinical setting. Anatomic study trans-orbital skull base petrosectomy Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Described in 1985, ‘Kawase’ subtemporal approach is still considered the workhorse for resection of middle fossa and petrous apex lesions. 1 This versatile approach offers a lateral trajectory to the anterior petrous ridge, Gasserian ganglion, petroclival region and ventro-medial posterior fossa. 1 – 3 The approach begins with a temporal craniotomy to expose the lateral middle fossa skull base. Epidural dissection along the skull base is followed medially using anatomic landmarks including foramen spinosum, foramen ovale, GSPN, and arcuate eminence, to identify and expose the ‘Kawase quadrangle’. While initially described for basilar artery aneurysm clipping, 1 the subtemporal extradural approach can also be used to resect cavernous sinus lesions by dissecting an interdural plane between the medial temporal and the lateral cavernous sinus wall. 2 , 4 Resection of anterior petrous and lateral cavernous sinus lesions using the subtemporal trajectory requires temporal lobe retraction. While the Kawase approach offers a wide view of the middle skull base, it has been criticized for complications associated with temporal lobe retraction. Lesions that are superior to the Gasserian ganglion or ones involving the petrous apex, may require excessive temporal lobe retraction. 3 – 6 Alternatively, lateral extensions of the endoscopic endonasal approach (EEA) have been described in recent years for resection of petroclival lesions. 4 , 7 – 9 Ventro-medial posterior fossa lesions have been approached as well by further extension of the EEA through the pterygo-palatine fossa (PPF), using either a contralateral trans nasal-septum approach, or a sub-labial Cauldwell-Luc approach into the Maxillary sinus. 7 , 8 While EEA has gained wide acceptance, resection of lesions that are lateral to the trigeminal divisions and Gasserian ganglion offer a formidable challenge via EEA. 8 More recently, transorbital neuroendoscopic (TONES) approaches have been described for resection of lesions involving the lateral cavernous sinus, trigeminal nerve divisions and anterior petrous ridge. 10 – 17 TONES approaches commonly follow intra-orbital dissection, removal of the lateral orbital wall and an anterior view of the medial middle fossa. While TONES is a promising approach to the medial middle fossa skull base and the lateral cavernous sinus, resection of anterior petrous ridge lesions is technically challenging. The orbital rim limits the surgical field of view to the anterior petrous ridge. 8 , 18 , 19 Several studies have examined removal of the lateral orbital rim in order to extend the surgical degree of freedom and allow safe drilling of the anterior petrous ridge. 18 – 24 Recent studies have shown that using TONES, access to the anterior petrous region is feasible. 4 , 8 , 18 , 21 In this cadaveric study, TONES was extended to provide a safe uninhibited trajectory to the petrous ridge and posterior fossa. The described extended transorbital neuroendoscopic ( e TONES) approach includes single-piece removal of the superior and lateral orbital rims. This in turn offers expanded surgical trajectory to middle fossa skull base, anterior petrous ridge, and ventro-lateral posterior fossa, while reducing globe retraction. The study examined the surgical field-of-view and anatomic constraints provided by the e TONES approach and compared these to previously described TONES approaches and the traditional Kawase subtemporal anterior petrosectomy. Materials and Methods Four embalmed and injected cadaveric heads were used for this study. All heads were naïve from prior cranial operations. KARL STORZ VITOM® HOPKINS® Telescope 0˚; KARL STORZ HOPKINS ® Straight Forward Telescope ˚0; and KARL STORZ HOPKINS ® Forward-Oblique Telescope 30˚; endonasal skull base instruments (KARL STORZ United States, El Segundo, CA) were used for the dissections. A total of 4 cadaveric heads were dissected in the following sequence: All 4 specimens underwent e TONES approach on one side. Three of the e TONES approaches were aimed at generating maximal exposure of the petrous ridge to allow an extensive petrosectomy. The final specimen underwent a slightly varied superior e TONES procedure, as described next, to provide surgical access to the anterior petrous apex and petroclival region. All four specimens then underwent traditional Kawase subtemporal anterior petrosectomy on the contralateral side to the e TONES. Of note, on a single specimen, an attempt was made to expose the petrous ridge via TONES with only lateral orbital rim removal. This approach provided an insufficient degree of freedom for surgical instruments and was therefore followed by e TONES according to the describe protocol. All specimens underwent thin sliced head CT scans before and after the bilateral petrosectomy. Using Brainlab iPlan Cranial 3.0 the anatomic limitations and size of petrosectomy were measured on all 8 sides and compared between e TONES and the traditional Kawase approach. eTONES dissection Protocol: A surgical microscope or exoscope is used for the initial exposure. 1. A superior eyelid skin incision is marked from the supraorbital notch medially to 2 cm lateral to the lateral canthus. 2. Orbicularis oculi muscle is dissected in a superior-lateral direction to expose the superior and lateral orbital rims. 3. The superior orbital rim is exposed starting medially at the supraorbital foramen, and the lateral orbital rim (fronto-zygomatic arch) exposed inferiorly to the zygoma. 4. The anterio-superior insertion of the temporalis muscle is dissected and reflected posteriorly to fully expose the fronto-zygomatic arch. 5. The globe is dissected in the periorbital plane and retracted medially. 6. A burr hole is made along the lateral edge of the superior orbital rim and frontal dura is exposed. 7. Epidural dissection of the frontal tip is performed by advancing a dissector in the epidural plane from the burr hole to the supraorbital foramen. 8. The medial vertical bony cut is marked on the superior orbital rim, lateral and adjacent to the supraorbital foramen. 9. Starting at the burr hole, while protecting the frontal dura with the epidural dissector, using bone scalpel or oscillating saw, a horizontal bony cut is fashioned along the superior orbital rim to the medial mark adjacent to the supraorbital foramen. 10. A vertical cut is performed at the medial mark and connected with the initial horizontal cut. This second vertical cut is continued posteriorly along the orbital roof for 2 cm, while protecting the globe and frontal dura. 11. A bony cut of the lateral orbital rim is performed next, beginning at the burr hole superiorly and ending at the root of the zygoma inferiorly. 12. While retracting the globe, an inferior horizontal cut of the lateral orbital rim is fashioned, just superior to the root of the zygoma. 13. While retracting the globe inferio-medially, using a chisel and hammer the final bony cut of the supero-lateral orbit is completed by linking the previous cuts. 14. The single piece superior and lateral orbital rims are removed. 15. The superficial lateral orbital wall and greater sphenoid wing are drilled next while the globe is retracted medially. 16. The recurrent meningeal artery transversing the lateral orbital wall is identified, coagulated and incised. 17. The Superior Orbital Fissure (SOF) and Inferior Orbital Fissure (IOF) are identified deep to the greater sphenoid wing. 18. Following SOF and IOF identification, the residual lateral orbital wall is drilled and the temporal dura is exposed. An neuroendoscope is used from this point for increased magnification and illumination. 19. SOF and IOF mark the superior, medial, and inferior borders of the approach. The remaining lateral orbital wall is drilled once these landmarks are clearly identified. 20. The SOF and IOF lateral bone edge is removed to expose a continuous dural plane extending from the periorbita anteriorly to the temporal dura. Standard e TONES – extended middle petrosectomy and exposure of Cerebello-Pontine Angle (CPA) and Internal Acoustic Canal (IAC): 21. The IOF bone edge is drilled flush with the middle fossa floor. 22. The middle fossa floor is then dissected [posterior-medially, exposing the epidural plane, and the foramen ovale with the third trigeminal division (V3). This marks the medial interdural dissection plane. 23. The interdural plane is dissected posteriorly between the medial temporal dura and the cavernous sinus lateral wall marked by the trigeminal divisions. 24. Interdural dissection is continued posteriorly towards the Gasserian Ganglion (GG). 25. Once the GG is identified, the epidural plane is dissected posterior-laterally to expose the anterior petrous ridge. 26. The superior petrosal sinus (SPS) marking the petrous ridge, and the Greater Speno-Palatine Nerve (GSPN), overlying the petrous ICA are identified as superior and inferior drilling limits, respectively. 27. The petrous ridge is drilled lateral to the Gasserian Ganglion, inferior to the SPS, and superior to GSPN to expose Internal Acoustic Canal (IAC) and the posterior fossa dura. 28. Dura is opened to expose the Cerebello-Pontine Angle (CPA) and Internal Acoustic Canal (IAC) contents. Superior e TONES – petroclival and petrous apex exposure: 24. The lesser sphenoid wing is drilled just superior-lateral to the Meningo-Orbital Band (MOB) and inferior frontal dura is exposed. 25. The MOB is incised to detach the middle fossa dura from the periorbita. 26. The interdural plane is dissected between the middle fossa dura laterally and the cavernous sinus lateral dura. 27. The superior division of the trigeminal nerve (V1) and the Occulomotor nerve (CNIII) are identified medial to the dissection plane. 28. Interdural dissection is continued posterior-medially along V1 until the petrous apex is identified, at the petroclival junction superior to the GG. 29. The anterio-medial petrous apex is drilled to expose posterior fossa dura. 30. Dura is opened to expose the superior-medial CPA and ventral midbrain. Key features of the described approach are shown in Figure 1 Results Three specimens underwent a standard e TONES approach, as described. The overall mean volume of petrous bone removed in the 3 standard e TONES approach was 0.84 ± 0.38 ml. In comparison, The mean volume of petrous bone removed in the 4 Kawase subtemporal approach was 0.72 ± 0.15 ml. Figure 2 depicts an example of the size and location of the petrosectomy offered by the standard e TONES vs. the Kawase subtemporal approach. The final specimen underwent a superior e TONES variation, and the total volume of petrous bone removed was only 0.07ml. This superior e TONES variation provided petrous apex and superior petroclival junction exposure as shown in Fig. 3. Table 1 lists the volume of petrous ridge that was removed on all specimens using the standard e TONES, the superior e TONES variation, and the Kawase approach. Substantial differences are noted between the e TONES and Kawase approaches in the viewing angle and field-of-view provided. The more lateral standard e TONES offered a straight on ventral-to-dorsal view of the IAC and CPA contents. The region that is superior and medial to the IAC, and lateral to the Gasserian Ganglion, can be identified clearly, along with its neurovascular anatomic landmarks using this approach. Conversely, Kawase subtemporal approach provides a clear view of the medial CPA and petroclival region, as the viewing angle is lateral-to-medial and is limited both in the superior and inferior planes. Figure 4 provides a schematic field of view analysis of the relative differences between the views that these approaches offer. As noted, a superior e TONES variation was completed on the final specimen, tailored to provide access to the petroclival region. In this approach, limited removal of the anterior petrous apex is completed, and a straight on ventral-to-dorsal exposure of the superior petroclival region is obtained, as seen in Fig. 3. While the volume of petrous bone removed on the superior e TONES variation was significantly smaller than both standard e TONES and the Kawase approach (0.07, 0.84 and 0.72 ml, respectively), superior e TONES variation ‘bridged-the-gap’ between the Kawase and standard e TONES in terms of petroclival and petrous apex exposure, as shown in Fig. 3. Discussion In this cadaveric anatomic study, we demonstrated an extended Transorbital neuroendoscopic ( e TONES) approach, which includes removal of supero-lateral orbital rim and lateral orbital wall, to overcome the anatomic limitations of the standard TONES allowing for a safe petrosectomy. We presented two variations to this approach, one for extensive middle petrosectomy, while the other tailored at the petrous apex and petroclival junction. We compared this novel surgical approach with its variations to the standard Kawase subtemporal approach, in terms of limitations, instrument maneuverability and viewing angle. The Transorbital neuroendoscopic (TONES) approach has been previously described by various authors that examined anatomic limitations, field-of-view, and safety of the approach, both on cadaveric and in clinical case series. 2 , 10 – 14 , 18 , 19 , 21 , 22 , 25 Various authors agree that superficial lesions along the greater sphenoid wing, anterior-lateral cavernous sinus and temporal tip can be safely resected using standard TONES approach without removal of the lateral orbital rim, using standard neuroendoscopic techniques. 21 , 26 – 28 More posterior lesions involving the posterior-lateral cavernous sinus, Gasserion ganglion, or middle fossa floor, are largely accessed via TONES with removal of the lateral orbital rim to increase instrument maneuverability. 8 , 14 , 15 , 18 , 21 , 23 Lesions that are even more posterior, extending into Meckel’s cave and posterior fossa, offer a formidable challenge using standard TONES approach. 4 , 7 , 8 , 14 We found that by completing a series of described surgical steps the superior and lateral orbital rims can be removed in a single bony piece, while the globe and frontal dura are protected. Single piece bone removal can assist in achieving satisfactory postoperative cosmetic outcomes. We also found that by complete removal of the lateral orbital wall, followed by a previously described TONES approach, wide endoscopic field-of-view and instrument maneuverability are attained. This in turn offers safe interdural medial temporal - cavernous sinus dissection, petrous apex exposure, and petrosectomy in an efficient manner with minimal temporal lobe retraction. e TONES was found superior to Kawase subtemporal approach in several ways. First, e TONES eyelid skin incision offers excellent postoperative cosmetic results when compared with the temporal skin incision, temporalis muscle retraction causing postoperative muscle wasting, and large temporal craniotomy required for subtemporal exposure. 26 , 28 Next, e TONES offers access to lesions involving the lateral cavernous sinus in a straight on, straightforward view that may be superior to the view offered via the subtemporal approach. Lesions involving the superior cavernous sinus may require extensive temporal lobe retraction using a subtemporal approach, while they are effortlessly accessible using e TONES. 2 , 6 , 9 , 20 , 29 Lesions involving the petroclival junction and petrous apex are also accessed via e TONES approach with minimal temporal retraction when compared to the subtemporal approach. Lastly, for lesions involving the middle petrous ridge, IAC region, and cerebello-pontine angle, the subtemporal approach again requires prolonged retraction and offers a lateral-to-medial view, 1 while e TONES requires less temporal retraction and a offers a ventral-to-dorsal view. e TONES was found inferior to Kawase subtemporal approach in several parameters. First, drilling of the lateral orbital rim may cause postoperative enophthalmos as well as early postoperative ocular pulsations transmitted from the frontal lobe. 21 , 26 , 30 e TONES also requires retraction of the globe and transient increase in ocular pressure. Limited retraction and close monitoring of the globe is required during surgery to avoid postoperative visual complication. Similar to endoscopic endonasal surgery, dural closure is challenging in e TONES, and is usually performed in multilayered manner. 19 , 21 , 26 Additionally, the ventral-to-dorsal surgical field-of-view along with limited instrument maneuverability, require neuroendoscopic skills, specific instrumentation, and may be technically challenging. In this regard e TONES is similar to other minimally invasive endoscopic approaches and is associated with a learning curve for most surgeons accustomed to microscopic surgical technique. The most noted limitation of this study is its cadaveric nature. While initial cadaveric studies are important for acquiring anatomic knowledge and surgical familiarity, clinical studies are crucial to fully examine novel surgical approach. Neuroendoscopic and minimally invasive cadaveric models may be all the more erroneous in this regard, as lack of bleeding that can overwhelm the surgical field, and cadaveric cerebral tissue retraction, are both non-representative. Following this cadaveric proof of concept study, a clinical case series must assess the applicability of e TONES approach. In conclusion, This anatomic study examined the feasibility of an extended transorbital neuroendoscopic ( e TONES) approaches for safe and efficient anterior and middle petrosectomy. e TONES provides a straight on, minimally invasive endoscopic surgical approach that is comparable to the Kawase subtemporal approach and may complement other surgical approaches for lesions involving the cavernous sinus, petroclival region, petrous ridge, and cerbellopontine angle. The described approach has yet to be examined in a clinical setting. Funding Acknowledgements Research reported in this publication was supported by an unrestricted investigator initiated research grant from KARL STORZ United States (El Segundo, CA). Table 1 – Volume of bone removed during bilteral petrosectomy on four cadaver heads. All four cadavers underwent Kawase subtemporal approach on one side. Three cadavers underwent standard e TONES while one cadaver (no.351) underwent superior variation e TONES on the side contralateral to Kawase. Cadaver no. e TONES type eTONES volume (ml) Kawase volume (ml) 322 standard 0.809 0.775 343 standard 0.487 0.558 348 standard 1.236 0.899 351 superior 0.074 0.642 Abbreviations TransOrbital Neuroendoscopic Surgery (TONES); extended TransOrbital Neuroendoscopic Surgery ( e TONES); Cerebello-Pontine Angle (CPA); Endoscopic Endonasal Approach (EEA); Pterygo-Palatine Fossa (PPF); Superior Petrosal Sinus (SPS); Superior Orbital Fissure (SOF); Inferior Orbital Fissure (IOF); Greater Petrosal Nerve (GSPN); Internal Acoustic Canal (IAC); Gasserian Ganglion (GG); Meningo-Orbital Band (MOB); Trigeminal Nerve (V1); Occulomotor Nerve (CNIII); Facial Nerve (CNVII) Declarations Funding: Research reported in this publication was supported by an unrestricted investigator initiated research grant from KARL STORZ United States (El Segundo, CA) Disclosures: The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article. Ethical standard This study was conducted on cadaveric specimens according to ethical guidelines and standards in an anatomic laboratory at the Seattle Science Foundation Funding Research reported in this publication was supported by an unrestricted investigator initiated research grant from KARL STORZ United States (El Segundo, CA) Conflicts of interest/Competing interests The authors have no competing interests to declare that are relevant to the content of this article. Availability of data and material All data for this study can be shared upon reasonable request. Code availability Code and statistical analysis in this study can be shared upon reasonable request. Authors' contributions All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Alon Orlev MD, Gil Kimchi MD, Eduardo Martinez del Campo, MD, Mitchell Young, Idan Levitan, MD. The first draft of the manuscript was written by Dr. Alon Orlev, Gil Kimchi MD, Idan Levitan, MD. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Consent to participate No identifying patient information was presented in this study. Consent for publication Authors are responsible for correctness of the statements provided in the manuscript. References Kawase T, Toya S, Shiobara R, Mine T. Transpetrosal approach for aneurysms of the lower basilar artery. J Neurosurg . 1985;63(6):857-861. doi:10.3171/JNS.1985.63.6.0857 Noiphithak R, Yanez-Siller JC, Barbero JMR, Otto BA, Carrau RL, Prevedello DM. Quantitative analysis of the surgical exposure and surgical freedom between transcranial and transorbital endoscopic anterior petrosectomies to the posterior fossa. J Neurosurg . 2019;131(2):569-577. doi:10.3171/2018.2.JNS172334 Tomio R, Horiguchi T, Borghei-Razavi H, Tamura R, Yoshida K, Kawase T. 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Brain and Spine . 2022;2. doi:10.1016/j.bas.2022.100891 Lin BJ, Ju DT, Wu YC, et al. Endoscopic transcanal transpetrosal approach to the petroclival region: a cadaveric study with comparison to the Kawase approach. Neurosurg Rev . 2021;44(4):2171-2179. doi:10.1007/s10143-020-01389-x Zoia C, Mantovani G, Müther M, et al. Through the orbit and beyond: Current state and future perspectives in endoscopic orbital surgery on behalf of the EANS frontiers committee in orbital tumors and the EANS skull base section. Brain and Spine . 2023;3. doi:10.1016/j.bas.2023.102669 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. 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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-4622673","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":327660112,"identity":"89713014-0b92-4a4f-ac13-61515e6758b2","order_by":0,"name":"Alon Orlev","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA10lEQVRIiWNgGAWjYDCCA2DSgoGBvQFIG1gQrUWCgYEHxDKQIEWLRAKUQQjw3T7A+OHjHgk5g5vPr274USDBwN/enYBXi+S5BGbJGc8kjA1u55Td7AE6TOLM2Q14tRicYWCQ5jkgkThzdk7aDR6gFgOJXIJamH8DtdTPnHkm7eYfIrWwgWxJ4JdgP3abKFskzzC2Wc44IGHYz5PDdlvGQIKHoF/4zjAfvvHhgI08G/vxZzff/LGR42/vxa+FgYGxAcrgMQCTBJSjAPYHpKgeBaNgFIyCEQQA/7hET93oKusAAAAASUVORK5CYII=","orcid":"","institution":"Swedish Neuroscience Institute","correspondingAuthor":true,"prefix":"","firstName":"Alon","middleName":"","lastName":"Orlev","suffix":""},{"id":327660113,"identity":"c11cced7-db65-4293-967d-db552c0b4fae","order_by":1,"name":"Gil Kimchi","email":"","orcid":"","institution":"Sheba Medical Center, Tel-Aviv University","correspondingAuthor":false,"prefix":"","firstName":"Gil","middleName":"","lastName":"Kimchi","suffix":""},{"id":327660115,"identity":"f1969851-f3c8-487d-8a20-949caadf1f55","order_by":2,"name":"Eduardo Martinez Campo","email":"","orcid":"","institution":"Swedish Neuroscience Institute","correspondingAuthor":false,"prefix":"","firstName":"Eduardo","middleName":"Martinez","lastName":"Campo","suffix":""},{"id":327660116,"identity":"89f207d0-5ac4-4661-850d-848566ba1c70","order_by":3,"name":"Mitchell Young","email":"","orcid":"","institution":"Seattle Science Foundation","correspondingAuthor":false,"prefix":"","firstName":"Mitchell","middleName":"","lastName":"Young","suffix":""},{"id":327660119,"identity":"296a5946-f2a1-4382-95f9-14ae536e8894","order_by":4,"name":"Idan Levitan","email":"","orcid":"","institution":"Rabin Medical Center","correspondingAuthor":false,"prefix":"","firstName":"Idan","middleName":"","lastName":"Levitan","suffix":""},{"id":327660120,"identity":"25856dc6-3571-4eab-9e87-bf43f56ecea0","order_by":5,"name":"Sagi Harnof","email":"","orcid":"","institution":"Rabin Medical Center","correspondingAuthor":false,"prefix":"","firstName":"Sagi","middleName":"","lastName":"Harnof","suffix":""},{"id":327660124,"identity":"f80d4875-1c00-457b-bad4-8d1be645cb03","order_by":6,"name":"Zachary Litvack","email":"","orcid":"","institution":"Swedish Neuroscience Institute","correspondingAuthor":false,"prefix":"","firstName":"Zachary","middleName":"","lastName":"Litvack","suffix":""}],"badges":[],"createdAt":"2024-06-22 16:38:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4622673/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4622673/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":61005500,"identity":"9816d4e9-11bd-47aa-b693-c534c793f1be","added_by":"auto","created_at":"2024-07-24 13:45:31","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":952403,"visible":true,"origin":"","legend":"\u003cp\u003eeTONES key steps. Exoscopic view (A-F). Myocutaneous dissection to expose superior and lateral orbital rims (A). Burr hole to expose frontal dura (B). Bony cuts using oscillating saw for single piece removal of superior and lateral orbital rims (C). Periorbital dissection to expose lateral orbital wall (D). Superficial drilling of lateral orbital wall or greater sphenoid wing (GSW) (E). Exposure of temporal tip dura (F). Neuroendoscopic view (G-L). Drilling of GSW toward SOF and IOF (G). Dissection of IOF leading to middle fossa dura (H) exposing V3 division of trigeminal nerve (I). Interdural dissection between trigeminal division (V1-V2) and temporal dura to expose Gasserian Ganglion and petrous ridge (J). Temporal dura retracted and anterior petrous ridge is drilled (K). Posterior fossa and internal acoustic canal (IAC) exposed (L). TD – temporal dura. V1-V3 – divisions of trigeminal nerve.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4622673/v1/b3dff109c0b20573dda11b4b.png"},{"id":61006676,"identity":"c243b2b0-a9af-49be-b6c3-1a9e7bb48059","added_by":"auto","created_at":"2024-07-24 13:53:31","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":267451,"visible":true,"origin":"","legend":"\u003cp\u003e3-dimensional depiction of petrous ridge bone resection on three specimens. Kawase is displayed in blue and \u003cem\u003ee\u003c/em\u003eTONES in red. (A) Specimen no.322 – Kawase on the left and \u003cem\u003ee\u003c/em\u003eTONES on the right side. (B) Specimen no.348 and (C) Specimen no.343 – Kawase on the right and \u003cem\u003ee\u003c/em\u003eTONES on the left side.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4622673/v1/1afd23847b777fb01969f75b.png"},{"id":61005501,"identity":"a6dfbd7b-0ff4-4784-b7e5-06fa112e5ecc","added_by":"auto","created_at":"2024-07-24 13:45:31","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":365685,"visible":true,"origin":"","legend":"\u003cp\u003e3-dimensional depiction of petrous ridge resected on a single specimen no.351. Kawase approach on the left and superior \u003cem\u003ee\u003c/em\u003eTONES variation on the right side.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4622673/v1/42fee4cf78220ff254a81f7c.png"},{"id":61006677,"identity":"08c20c71-4d5c-4186-a7c6-69afa2f1e368","added_by":"auto","created_at":"2024-07-24 13:53:31","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":244339,"visible":true,"origin":"","legend":"\u003cp\u003eComparative petrous ridge trajectories and field-of-view obtained by the various surgical approaches. Kawase in blue, \u003cem\u003ee\u003c/em\u003eTONES in red, and superior \u003cem\u003ee\u003c/em\u003eTONES variation in green. Cavernous sinus is displayed in yellow.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4622673/v1/ecbc988a0d173d8688aa2de6.png"},{"id":72744377,"identity":"7003d179-5f5f-40b5-9b4b-58c4d9d944b9","added_by":"auto","created_at":"2025-01-01 11:46:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2896880,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4622673/v1/430d272a-6750-4d3a-bc6d-02d496313586.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Anterior and Middle Petrosectomy via an Extended Transorbital Neuroendoscopic Approach: Anatomic Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eDescribed in 1985, \u0026lsquo;Kawase\u0026rsquo; subtemporal approach is still considered the workhorse for resection of middle fossa and petrous apex lesions.\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e This versatile approach offers a lateral trajectory to the anterior petrous ridge, Gasserian ganglion, petroclival region and ventro-medial posterior fossa.\u003csup\u003e\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e The approach begins with a temporal craniotomy to expose the lateral middle fossa skull base. Epidural dissection along the skull base is followed medially using anatomic landmarks including foramen spinosum, foramen ovale, GSPN, and arcuate eminence, to identify and expose the \u0026lsquo;Kawase quadrangle\u0026rsquo;. While initially described for basilar artery aneurysm clipping,\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e the subtemporal extradural approach can also be used to resect cavernous sinus lesions by dissecting an interdural plane between the medial temporal and the lateral cavernous sinus wall.\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e Resection of anterior petrous and lateral cavernous sinus lesions using the subtemporal trajectory requires temporal lobe retraction. While the Kawase approach offers a wide view of the middle skull base, it has been criticized for complications associated with temporal lobe retraction. Lesions that are superior to the Gasserian ganglion or ones involving the petrous apex, may require excessive temporal lobe retraction.\u003csup\u003e\u003cspan additionalcitationids=\"CR4 CR5\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eAlternatively, lateral extensions of the endoscopic endonasal approach (EEA) have been described in recent years for resection of petroclival lesions.\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e Ventro-medial posterior fossa lesions have been approached as well by further extension of the EEA through the pterygo-palatine fossa (PPF), using either a contralateral trans nasal-septum approach, or a sub-labial Cauldwell-Luc approach into the Maxillary sinus.\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e While EEA has gained wide acceptance, resection of lesions that are lateral to the trigeminal divisions and Gasserian ganglion offer a formidable challenge via EEA. \u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eMore recently, transorbital neuroendoscopic (TONES) approaches have been described for resection of lesions involving the lateral cavernous sinus, trigeminal nerve divisions and anterior petrous ridge.\u003csup\u003e\u003cspan additionalcitationids=\"CR11 CR12 CR13 CR14 CR15 CR16\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e TONES approaches commonly follow intra-orbital dissection, removal of the lateral orbital wall and an anterior view of the medial middle fossa. While TONES is a promising approach to the medial middle fossa skull base and the lateral cavernous sinus, resection of anterior petrous ridge lesions is technically challenging. The orbital rim limits the surgical field of view to the anterior petrous ridge.\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e Several studies have examined removal of the lateral orbital rim in order to extend the surgical degree of freedom and allow safe drilling of the anterior petrous ridge.\u003csup\u003e\u003cspan additionalcitationids=\"CR19 CR20 CR21 CR22 CR23\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e Recent studies have shown that using TONES, access to the anterior petrous region is feasible.\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eIn this cadaveric study, TONES was extended to provide a safe uninhibited trajectory to the petrous ridge and posterior fossa. The described extended transorbital neuroendoscopic (\u003cem\u003ee\u003c/em\u003eTONES) approach includes single-piece removal of the superior and lateral orbital rims. This in turn offers expanded surgical trajectory to middle fossa skull base, anterior petrous ridge, and ventro-lateral posterior fossa, while reducing globe retraction. The study examined the surgical field-of-view and anatomic constraints provided by the \u003cem\u003ee\u003c/em\u003eTONES approach and compared these to previously described TONES approaches and the traditional Kawase subtemporal anterior petrosectomy.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eFour embalmed and injected cadaveric heads were used for this study. All heads were na\u0026iuml;ve from prior cranial operations. KARL\u0026nbsp;STORZ\u0026nbsp;VITOM\u0026reg; HOPKINS\u0026reg; Telescope 0˚; KARL\u0026nbsp;STORZ\u0026nbsp;HOPKINS \u0026reg; Straight Forward Telescope ˚0; and KARL\u0026nbsp;STORZ\u0026nbsp;HOPKINS \u0026reg; Forward-Oblique Telescope 30˚; endonasal skull base instruments (KARL\u0026nbsp;STORZ\u0026nbsp;United States, El Segundo, CA) were used for the dissections.\u003c/p\u003e\n\u003cp\u003eA total of 4 cadaveric heads were dissected in the following sequence: All 4 specimens underwent \u003cem\u003ee\u003c/em\u003eTONES approach on one side. Three of the \u003cem\u003ee\u003c/em\u003eTONES approaches were aimed at generating maximal exposure of the petrous ridge to allow an extensive petrosectomy. The final specimen underwent a slightly varied superior \u003cem\u003ee\u003c/em\u003eTONES procedure, as described next, to provide surgical access to the anterior petrous apex and petroclival region. All four specimens then underwent traditional Kawase subtemporal anterior petrosectomy on the contralateral side to the \u003cem\u003ee\u003c/em\u003eTONES. \u0026nbsp;Of note, on a single specimen, an attempt was made to expose the petrous ridge via TONES with only lateral orbital rim removal. This approach provided an insufficient degree of freedom for surgical instruments and was therefore followed by \u003cem\u003ee\u003c/em\u003eTONES according to the describe protocol. All specimens underwent thin sliced head CT scans before and after the bilateral petrosectomy. Using Brainlab iPlan Cranial 3.0 the anatomic limitations and size of petrosectomy were measured on all 8 sides and compared between \u003cem\u003ee\u003c/em\u003eTONES and the traditional Kawase approach.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cu\u003eeTONES\u003c/u\u003e\u003c/em\u003e\u003cu\u003e\u0026nbsp;dissection Protocol:\u0026nbsp;\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eA surgical microscope or exoscope is used for the initial exposure.\u003c/p\u003e\n\u003cp\u003e1. \u0026nbsp; \u0026nbsp;A superior eyelid skin incision is marked from the supraorbital notch medially to 2 cm lateral to the lateral canthus.\u003c/p\u003e\n\u003cp\u003e2. \u0026nbsp; \u0026nbsp;Orbicularis oculi muscle is dissected in a superior-lateral direction to expose the superior and lateral orbital rims.\u003c/p\u003e\n\u003cp\u003e3. \u0026nbsp; \u0026nbsp;The superior orbital rim is exposed starting medially at the supraorbital foramen, and the lateral orbital rim (fronto-zygomatic arch) exposed inferiorly to the zygoma.\u003c/p\u003e\n\u003cp\u003e4. \u0026nbsp; \u0026nbsp;The anterio-superior insertion of the temporalis muscle is dissected and reflected posteriorly to fully expose the fronto-zygomatic arch.\u003c/p\u003e\n\u003cp\u003e5. \u0026nbsp; \u0026nbsp;The globe is dissected in the periorbital plane and retracted medially.\u003c/p\u003e\n\u003cp\u003e6. \u0026nbsp; \u0026nbsp;A burr hole is made along the lateral edge of the superior orbital rim and frontal dura is exposed.\u003c/p\u003e\n\u003cp\u003e7. \u0026nbsp; \u0026nbsp;Epidural dissection of the frontal tip is performed by advancing a dissector in the epidural plane from the burr hole to the supraorbital foramen.\u003c/p\u003e\n\u003cp\u003e8. \u0026nbsp; \u0026nbsp;The medial vertical bony cut is marked on the superior orbital rim, lateral and adjacent to the supraorbital foramen.\u003c/p\u003e\n\u003cp\u003e9. \u0026nbsp; \u0026nbsp;Starting at the burr hole, while protecting the frontal dura with the epidural dissector, using bone scalpel or oscillating saw, a horizontal bony cut is fashioned along the superior orbital rim to the medial mark adjacent to the supraorbital foramen.\u003c/p\u003e\n\u003cp\u003e10. \u0026nbsp;A vertical cut is performed at the medial mark and connected with the initial horizontal cut. This second vertical cut is continued posteriorly along the orbital roof for 2 cm, while protecting the globe and frontal dura.\u003c/p\u003e\n\u003cp\u003e11. \u0026nbsp;A bony cut of the lateral orbital rim is performed next, beginning at the burr hole superiorly and ending at the root of the zygoma inferiorly.\u003c/p\u003e\n\u003cp\u003e12. \u0026nbsp;While retracting the globe, an inferior horizontal cut of the lateral orbital rim is fashioned, just superior to the root of the zygoma.\u003c/p\u003e\n\u003cp\u003e13. \u0026nbsp;While retracting the globe inferio-medially, using a chisel and hammer the final bony cut of the supero-lateral orbit is completed by linking the previous cuts.\u003c/p\u003e\n\u003cp\u003e14. \u0026nbsp;The single piece superior and lateral orbital rims are removed.\u003c/p\u003e\n\u003cp\u003e15. \u0026nbsp;The superficial lateral orbital wall and greater sphenoid wing are drilled next while the globe is retracted medially.\u003c/p\u003e\n\u003cp\u003e16. \u0026nbsp;The recurrent meningeal artery transversing the lateral orbital wall is identified, coagulated and incised.\u003c/p\u003e\n\u003cp\u003e17. \u0026nbsp;The Superior Orbital Fissure (SOF) and Inferior Orbital Fissure (IOF) are identified deep to the greater sphenoid wing.\u003c/p\u003e\n\u003cp\u003e18. \u0026nbsp;Following SOF and IOF identification, the residual lateral orbital wall is drilled and the temporal dura is exposed.\u003c/p\u003e\n\u003cp\u003eAn neuroendoscope is used from this point for increased magnification and illumination.\u003c/p\u003e\n\u003cp\u003e19. \u0026nbsp;SOF and IOF mark the superior, medial, and inferior borders of the approach. The remaining lateral orbital wall is drilled once these landmarks are clearly identified.\u003c/p\u003e\n\u003cp\u003e20. \u0026nbsp;The SOF and IOF lateral bone edge is removed to expose a continuous dural plane extending from the periorbita anteriorly to the temporal dura.\u003c/p\u003e\n\u003cp\u003eStandard \u003cem\u003ee\u003c/em\u003eTONES \u0026ndash; extended middle petrosectomy and exposure of Cerebello-Pontine Angle (CPA) and Internal Acoustic Canal (IAC):\u003c/p\u003e\n\u003cp\u003e21. \u0026nbsp;The IOF bone edge is drilled flush with the middle fossa floor.\u003c/p\u003e\n\u003cp\u003e22. \u0026nbsp;The middle fossa floor is then dissected [posterior-medially, exposing the epidural plane, and the foramen ovale with the third trigeminal division (V3). This marks the medial interdural dissection plane.\u003c/p\u003e\n\u003cp\u003e23. \u0026nbsp;The interdural plane is dissected posteriorly between the medial temporal dura and the cavernous sinus lateral wall marked by the trigeminal divisions.\u003c/p\u003e\n\u003cp\u003e24. \u0026nbsp;Interdural dissection is continued posteriorly towards the Gasserian Ganglion (GG).\u003c/p\u003e\n\u003cp\u003e25. \u0026nbsp;Once the GG is identified, the epidural plane is dissected posterior-laterally to expose the anterior petrous ridge.\u003c/p\u003e\n\u003cp\u003e26. \u0026nbsp;The superior petrosal sinus (SPS) marking the petrous ridge, and the Greater Speno-Palatine Nerve (GSPN), overlying the petrous ICA are identified as superior and inferior drilling limits, respectively.\u003c/p\u003e\n\u003cp\u003e27. \u0026nbsp;The petrous ridge is drilled lateral to the Gasserian Ganglion, inferior to the SPS, and superior to GSPN to expose Internal Acoustic Canal (IAC) and the posterior fossa dura.\u003c/p\u003e\n\u003cp\u003e28. \u0026nbsp;Dura is opened to expose the Cerebello-Pontine Angle (CPA) and Internal Acoustic Canal (IAC) contents.\u003c/p\u003e\n\u003cp\u003eSuperior \u003cem\u003ee\u003c/em\u003eTONES \u0026ndash; petroclival and petrous apex exposure:\u003c/p\u003e\n\u003cp\u003e24. \u0026nbsp;The lesser sphenoid wing is drilled just superior-lateral to the Meningo-Orbital Band (MOB) and inferior frontal dura is exposed.\u003c/p\u003e\n\u003cp\u003e25. \u0026nbsp;The MOB is incised to detach the middle fossa dura from the periorbita.\u003c/p\u003e\n\u003cp\u003e26. \u0026nbsp;The interdural plane is dissected between the middle fossa dura laterally and the cavernous sinus lateral dura.\u003c/p\u003e\n\u003cp\u003e27. \u0026nbsp;The superior division of the trigeminal nerve (V1) and the Occulomotor nerve (CNIII) are identified medial to the dissection plane.\u003c/p\u003e\n\u003cp\u003e28. \u0026nbsp;Interdural dissection is continued posterior-medially along V1 until the petrous apex is identified, at the petroclival junction superior to the GG.\u003c/p\u003e\n\u003cp\u003e29. \u0026nbsp;The anterio-medial petrous apex is drilled to expose posterior fossa dura.\u003c/p\u003e\n\u003cp\u003e30. \u0026nbsp;Dura is opened to expose the superior-medial CPA and ventral midbrain.\u003c/p\u003e\n\u003cp\u003eKey features of the described approach are shown in \u003cu\u003eFigure 1\u003c/u\u003e\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThree specimens underwent a standard \u003cem\u003ee\u003c/em\u003eTONES approach, as described. The overall mean volume of petrous bone removed in the 3 standard \u003cem\u003ee\u003c/em\u003eTONES approach was 0.84\u0026thinsp;\u0026plusmn;\u0026thinsp;0.38 ml. In comparison, The mean volume of petrous bone removed in the 4 Kawase subtemporal approach was 0.72\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15 ml. Figure\u0026nbsp;2 depicts an example of the size and location of the petrosectomy offered by the standard \u003cem\u003ee\u003c/em\u003eTONES vs. the Kawase subtemporal approach. The final specimen underwent a superior \u003cem\u003ee\u003c/em\u003eTONES variation, and the total volume of petrous bone removed was only 0.07ml. This superior \u003cem\u003ee\u003c/em\u003eTONES variation provided petrous apex and superior petroclival junction exposure as shown in Fig.\u0026nbsp;3. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e lists the volume of petrous ridge that was removed on all specimens using the standard \u003cem\u003ee\u003c/em\u003eTONES, the superior \u003cem\u003ee\u003c/em\u003eTONES variation, and the Kawase approach.\u003c/p\u003e \u003cp\u003eSubstantial differences are noted between the \u003cem\u003ee\u003c/em\u003eTONES and Kawase approaches in the viewing angle and field-of-view provided. The more lateral standard \u003cem\u003ee\u003c/em\u003eTONES offered a straight on ventral-to-dorsal view of the IAC and CPA contents. The region that is superior and medial to the IAC, and lateral to the Gasserian Ganglion, can be identified clearly, along with its neurovascular anatomic landmarks using this approach. Conversely, Kawase subtemporal approach provides a clear view of the medial CPA and petroclival region, as the viewing angle is lateral-to-medial and is limited both in the superior and inferior planes. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e provides a schematic field of view analysis of the relative differences between the views that these approaches offer.\u003c/p\u003e \u003cp\u003eAs noted, a superior \u003cem\u003ee\u003c/em\u003eTONES variation was completed on the final specimen, tailored to provide access to the petroclival region. In this approach, limited removal of the anterior petrous apex is completed, and a straight on ventral-to-dorsal exposure of the superior petroclival region is obtained, as seen in Fig.\u0026nbsp;3. While the volume of petrous bone removed on the superior \u003cem\u003ee\u003c/em\u003eTONES variation was significantly smaller than both standard \u003cem\u003ee\u003c/em\u003eTONES and the Kawase approach (0.07, 0.84 and 0.72 ml, respectively), superior \u003cem\u003ee\u003c/em\u003eTONES variation \u0026lsquo;bridged-the-gap\u0026rsquo; between the Kawase and standard \u003cem\u003ee\u003c/em\u003eTONES in terms of petroclival and petrous apex exposure, as shown in Fig.\u0026nbsp;3.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this cadaveric anatomic study, we demonstrated an extended Transorbital neuroendoscopic (\u003cem\u003ee\u003c/em\u003eTONES) approach, which includes removal of supero-lateral orbital rim and lateral orbital wall, to overcome the anatomic limitations of the standard TONES allowing for a safe petrosectomy. We presented two variations to this approach, one for extensive middle petrosectomy, while the other tailored at the petrous apex and petroclival junction. We compared this novel surgical approach with its variations to the standard Kawase subtemporal approach, in terms of limitations, instrument maneuverability and viewing angle.\u003c/p\u003e \u003cp\u003eThe Transorbital neuroendoscopic (TONES) approach has been previously described by various authors that examined anatomic limitations, field-of-view, and safety of the approach, both on cadaveric and in clinical case series.\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan additionalcitationids=\"CR11 CR12 CR13\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e,\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e Various authors agree that superficial lesions along the greater sphenoid wing, anterior-lateral cavernous sinus and temporal tip can be safely resected using standard TONES approach without removal of the lateral orbital rim, using standard neuroendoscopic techniques.\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan additionalcitationids=\"CR27\" citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e More posterior lesions involving the posterior-lateral cavernous sinus, Gasserion ganglion, or middle fossa floor, are largely accessed via TONES with removal of the lateral orbital rim to increase instrument maneuverability.\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e Lesions that are even more posterior, extending into Meckel\u0026rsquo;s cave and posterior fossa, offer a formidable challenge using standard TONES approach.\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eWe found that by completing a series of described surgical steps the superior and lateral orbital rims can be removed in a single bony piece, while the globe and frontal dura are protected. Single piece bone removal can assist in achieving satisfactory postoperative cosmetic outcomes. We also found that by complete removal of the lateral orbital wall, followed by a previously described TONES approach, wide endoscopic field-of-view and instrument maneuverability are attained. This in turn offers safe interdural medial temporal - cavernous sinus dissection, petrous apex exposure, and petrosectomy in an efficient manner with minimal temporal lobe retraction.\u003c/p\u003e \u003cp\u003e \u003cem\u003ee\u003c/em\u003eTONES was found superior to Kawase subtemporal approach in several ways. First, \u003cem\u003ee\u003c/em\u003eTONES eyelid skin incision offers excellent postoperative cosmetic results when compared with the temporal skin incision, temporalis muscle retraction causing postoperative muscle wasting, and large temporal craniotomy required for subtemporal exposure.\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e,\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e Next, \u003cem\u003ee\u003c/em\u003eTONES offers access to lesions involving the lateral cavernous sinus in a straight on, straightforward view that may be superior to the view offered via the subtemporal approach. Lesions involving the superior cavernous sinus may require extensive temporal lobe retraction using a subtemporal approach, while they are effortlessly accessible using \u003cem\u003ee\u003c/em\u003eTONES.\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e,\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e Lesions involving the petroclival junction and petrous apex are also accessed via \u003cem\u003ee\u003c/em\u003eTONES approach with minimal temporal retraction when compared to the subtemporal approach. Lastly, for lesions involving the middle petrous ridge, IAC region, and cerebello-pontine angle, the subtemporal approach again requires prolonged retraction and offers a lateral-to-medial view,\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e while \u003cem\u003ee\u003c/em\u003eTONES requires less temporal retraction and a offers a ventral-to-dorsal view.\u003c/p\u003e \u003cp\u003e \u003cem\u003ee\u003c/em\u003eTONES was found inferior to Kawase subtemporal approach in several parameters. First, drilling of the lateral orbital rim may cause postoperative enophthalmos as well as early postoperative ocular pulsations transmitted from the frontal lobe.\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e,\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e \u003cem\u003ee\u003c/em\u003eTONES also requires retraction of the globe and transient increase in ocular pressure. Limited retraction and close monitoring of the globe is required during surgery to avoid postoperative visual complication. Similar to endoscopic endonasal surgery, dural closure is challenging in \u003cem\u003ee\u003c/em\u003eTONES, and is usually performed in multilayered manner.\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e Additionally, the ventral-to-dorsal surgical field-of-view along with limited instrument maneuverability, require neuroendoscopic skills, specific instrumentation, and may be technically challenging. In this regard \u003cem\u003ee\u003c/em\u003eTONES is similar to other minimally invasive endoscopic approaches and is associated with a learning curve for most surgeons accustomed to microscopic surgical technique.\u003c/p\u003e \u003cp\u003eThe most noted limitation of this study is its cadaveric nature. While initial cadaveric studies are important for acquiring anatomic knowledge and surgical familiarity, clinical studies are crucial to fully examine novel surgical approach. Neuroendoscopic and minimally invasive cadaveric models may be all the more erroneous in this regard, as lack of bleeding that can overwhelm the surgical field, and cadaveric cerebral tissue retraction, are both non-representative. Following this cadaveric proof of concept study, a clinical case series must assess the applicability of \u003cem\u003ee\u003c/em\u003eTONES approach.\u003c/p\u003e \u003cp\u003eIn conclusion, This anatomic study examined the feasibility of an extended transorbital neuroendoscopic (\u003cem\u003ee\u003c/em\u003eTONES) approaches for safe and efficient anterior and middle petrosectomy. \u003cem\u003ee\u003c/em\u003eTONES provides a straight on, minimally invasive endoscopic surgical approach that is comparable to the Kawase subtemporal approach and may complement other surgical approaches for lesions involving the cavernous sinus, petroclival region, petrous ridge, and cerbellopontine angle. The described approach has yet to be examined in a clinical setting.\u003c/p\u003e \u003cp\u003eFunding Acknowledgements\u003c/p\u003e \u003cp\u003eResearch reported in this publication was supported by an unrestricted investigator initiated research grant from KARL STORZ United States (El Segundo, CA).\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\u003e\u0026ndash; Volume of bone removed during bilteral petrosectomy on four cadaver heads. All four cadavers underwent Kawase subtemporal approach on one side. Three cadavers underwent standard \u003cem\u003ee\u003c/em\u003eTONES while one cadaver (no.351) underwent superior variation \u003cem\u003ee\u003c/em\u003eTONES on the side contralateral to Kawase.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCadaver no.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ee\u003c/em\u003eTONES type\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eeTONES volume (ml)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eKawase volume (ml)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e322\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003estandard\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.809\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.775\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e343\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003estandard\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.487\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.558\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e348\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003estandard\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.236\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.899\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e351\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003esuperior\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.074\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.642\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\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eTransOrbital Neuroendoscopic Surgery (TONES); extended TransOrbital Neuroendoscopic Surgery (\u003cem\u003ee\u003c/em\u003eTONES); Cerebello-Pontine Angle (CPA); Endoscopic Endonasal Approach (EEA); Pterygo-Palatine Fossa (PPF); Superior Petrosal Sinus (SPS); Superior Orbital Fissure (SOF); Inferior Orbital Fissure (IOF); Greater Petrosal Nerve (GSPN); Internal Acoustic Canal (IAC); Gasserian Ganglion (GG); Meningo-Orbital Band (MOB); Trigeminal Nerve (V1); Occulomotor Nerve (CNIII); Facial Nerve (CNVII)\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003eResearch reported in this publication was supported by an unrestricted investigator initiated research grant from KARL\u0026nbsp;STORZ\u0026nbsp;United States (El Segundo, CA)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDisclosures:\u0026nbsp;\u003c/strong\u003eThe authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.\u003cu\u003e\u003cbr\u003e\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eEthical standard\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted on cadaveric specimens according to ethical guidelines and standards in an anatomic laboratory at the Seattle Science Foundation \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eFunding\u003c/em\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eResearch reported in this publication was supported by an unrestricted investigator initiated research grant from KARL\u0026nbsp;STORZ\u0026nbsp;United States (El Segundo, CA)\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eConflicts of interest/Competing interests\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no competing interests to declare that are relevant to the content of this article.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAvailability of data and material\u003c/em\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll data for this study can be shared upon reasonable request.\u003cbr\u003e\u003cem\u003eCode availability\u003c/em\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCode and statistical analysis in this study can be shared upon reasonable request.\u003cbr\u003e\u003cem\u003eAuthors\u0026apos; contributions\u003c/em\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Alon Orlev MD, Gil Kimchi MD, Eduardo Martinez del Campo, MD, Mitchell Young, Idan Levitan, MD. The first draft of the manuscript was written by Dr. Alon Orlev, Gil Kimchi MD, Idan Levitan, MD. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u0026nbsp;\u003cbr\u003e\u0026nbsp;\u003cem\u003eConsent to participate\u003c/em\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNo identifying patient information was presented in this study.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eConsent for publication\u003c/em\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAuthors are responsible for correctness of the statements provided in the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eKawase T, Toya S, Shiobara R, Mine T. 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Through the orbit and beyond: Current state and future perspectives in endoscopic orbital surgery on behalf of the EANS frontiers committee in orbital tumors and the EANS skull base section. \u003cem\u003eBrain and Spine\u003c/em\u003e. 2023;3. doi:10.1016/j.bas.2023.102669\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":"Anatomic study, trans-orbital, skull base, petrosectomy","lastPublishedDoi":"10.21203/rs.3.rs-4622673/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4622673/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eBackground\u003c/b\u003e\u003c/p\u003e \u003cp\u003eTransorbital neuroendoscopic (TONES) approaches have been described for resection of spheno-orbital, cavernous sinus, and Gasserian ganglion lesions. Lesions involving the petrous apex and cerebello-pontine angle (CPA) offer a formidable challenge via standard TONES approaches. This cadaveric study examined the surgical field-of-view and anatomic constraints provided by a novel extended transorbital neuroendoscopic (\u003cem\u003ee\u003c/em\u003eTONES) approach and compared these to previously described TONES approaches and the traditional subtemporal anterior petrosectomy.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMethods\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThe \u003cem\u003ee\u003c/em\u003eTONES approach includes single-piece removal of the superior and lateral orbital rims. This in turn offers expanded surgical trajectory to middle fossa skull base, anterior petrous ridge, and ventro-lateral posterior fossa, while reducing globe retraction. Four cadaveric heads underwent \u003cem\u003ee\u003c/em\u003eTONES approach on one side and traditional subtemporal anterior petrosectomy on the contralateral side. Petrosectomy volume, location, and posterior fossa field-of-view were compared between the two approaches.\u003c/p\u003e\u003cp\u003e\u003cb\u003eResults\u003c/b\u003e\u003c/p\u003e \u003cp\u003eMean volume of petrous bone removed in the standard \u003cem\u003ee\u003c/em\u003eTONES was 0.84\u0026thinsp;\u0026plusmn;\u0026thinsp;0.38 ml. In comparison, the mean volume of petrous bone removed in the subtemporal approach was 0.72\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15 ml. On a single specimen, a superior \u003cem\u003ee\u003c/em\u003eTONES variation was performed, tailored to provide access to the petrous apex and petroclival region, and 0.07ml of petrous bone was removed. Standard \u003cem\u003ee\u003c/em\u003eTONES offered a straight on ventral-to-dorsal view of the internal acoustic canal and CPA contents. Conversely, traditional subtemporal approach, provided an unobstructed view of the medial CPA and petroclival region, with a lateral-to-medial viewing angle. Superior \u003cem\u003ee\u003c/em\u003eTONES variation \u0026lsquo;bridges-the-gap\u0026rsquo; between standard \u003cem\u003ee\u003c/em\u003eTONES and subtemporal approaches in terms of petroclival and petrous apex exposure.\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusion\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cem\u003ee\u003c/em\u003eTONES provides a straight on, minimally invasive endoscopic surgical approach that is comparable to the traditional subtemporal approach and may complement other surgical approaches for lesions involving the cavernous sinus, petroclival region, petrous ridge, and CPA. The describ\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003eed approach has yet to be examined in a clinical setting.\u003c/p\u003e","manuscriptTitle":"Anterior and Middle Petrosectomy via an Extended Transorbital Neuroendoscopic Approach: Anatomic Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-24 13:45:26","doi":"10.21203/rs.3.rs-4622673/v1","editorialEvents":[{"type":"communityComments","content":1}],"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":"f41c5643-01f9-4b8b-8b37-0c4bc27c53e8","owner":[],"postedDate":"July 24th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-01-01T11:38:25+00:00","versionOfRecord":[],"versionCreatedAt":"2024-07-24 13:45:26","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4622673","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4622673","identity":"rs-4622673","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}