Invasion of the CS is one of the limiting factors for total resection for PitNet tumors with cure rates less than 30%. Extended approaches may be considered in selective and well-studied cases of secreting adenomas.
We describe the key steps of the endoscopic transcavernous approach for functional pituitary adenomas with a video illustration. The surgical anatomy is described along with the advantages and limitations of this approach.
A detailed knowledge of CS anatomy and familiarity with this surgical approach acquired in the laboratory is essential. Proper instrumentation is critical to decrease the risks of vascular injury

Daniel, R.T.

Messerer, M.

Starnoni, D.

Acta Neurochirurgica

English

Serveur académique lausannois

HOW I DO ITActa Neurochirurgica         (2024) 166:273 https://doi.org/10.1007/s00701-024-06168-xCS. The inferior pituitary artery is located in this compart-ment, it has an infero-medial trajectory in the direction of the dorsum sellae. It may arise independently from the short vertical segment or as a branch of the meningohypophyseal trunk. The abducens nerve lies in the lowest portion of this compartment and runs parallel, just inferior, to the horizon-tal segment of the ICA at the level of the lateral compart-ment [5]. Several ligaments insert at the level of the medial wall of the CS [10]. The strongest and most consistent is the carotidoclinoid ligament (CCL), which is part of the proximal dural ring and fuses with the interclinoid liga-ment. Other ligaments are the inferior (IPL) (connecting the medial wall with the anterior wall of the SC), superior (SPL) (connects the medial wall with the horizontal portion of the ICA) and posterior (PPL) (in close anatomical relationship with the inferior pituitary artery) parasellar ligaments.Description of the techniqueThe patient is placed in a supine position with the head rest-ing on a horseshoe head-holder and turned approximately 15 degrees toward the right shoulder and 10–15 degrees of neck flexion. Topical mucosal decongestants are used. Magnetic surgical navigation based on a preoperative com-puted tomography (CT) scan and a magnetic resonance imaging (MRI) is used(Fig. 1). For tumors projecting pre-dominantly to one side of the sella and extending into the Relevant surgical anatomyThe parasellar section of the internal carotid artery (ICA) consists of the cavernous and clinoid segments. The cav-ernous segment is a continuation of the paraclival segment at the level of the short vertical segment where the artery has an oblique trajectory posteriorly and delimits the infe-rior compartment of the cavernous sinus (CS), which is bor-dered medially by the medial wall of the CS, posteriorly by the short vertical segment, and superiorly by the horizontal segment of the ICA. The anterior genu of the ICA and the horizontal segment delimit the superior compartment of the CS, superiorly and laterally this compartment is delimited by the roof of the CS, the clinoid and oculomotor triangle. The posterior compartment is bounded by the short vertical segment, the posterior genu and the posterior wall of the   Daniele StarnoniDaniele.starnoni@chuv.ch1 Department of Clinical Neurosciences, Neurosurgery Service and Gamma Knife Center, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland2 Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), Lausanne, Switzerland3 Department of Neurosurgery, University Hospital of Lausanne, Rue du Bugnon 46, Lausanne  CH-1011, SwitzerlandAbstractBackground Invasion of the CS is one of the limiting factors for total resection for PitNet tumors with cure rates less than 30%. Extended approaches may be considered in selective and well-studied cases of secreting adenomas.Method We describe the key steps of the endoscopic transcavernous approach for functional pituitary adenomas with a video illustration. The surgical anatomy is described along with the advantages and limitations of this approach.Conclusion A detailed knowledge of CS anatomy and familiarity with this surgical approach acquired in the laboratory is essential. Proper instrumentation is critical to decrease the risks of vascular injury.Keywords Cavernous sinus · Endoscopic approach · PitNet · Pituitary adenomasReceived: 9 April 2024 / Accepted: 8 June 2024© The Author(s) 2024Endoscopic transcavernous approach for functional pituitary adenomasDaniele Starnoni1,2,3 · Roy T. Daniel1,2,3 · Mahmoud Messerer1,2,31 3Acta NeurochirurgicaCS, the contralateral uninostril approach is used [1], given that exposure across the midline to the contralateral sella and CS area is consistently wider than to the ipsilateral side [6]. The middle turbinate is gently displaced laterally with a Cottle elevator in order to expose the junction of the keel of the sphenoid and the posterior nasal septum. The posterior septal mucosa is cauterized and incised with a bipolar cau-tery and reflected laterally to expose the ipsilateral sphenoid ostium. The posterior nasal septum is then displaced off the midline to allow exposure of the contralateral ostium.To access the anterior wall of the CS a wide sphenoid-otomy is performed to allow for the necessary lateral exposure(Fig. 2A).Septations are removed down to the sella or over the ICA avoiding any excessive torquing of the bone fragments. The sellar bone is then removed from CS to CS and from the sel-lar floor inferiorly to the tuberculum sella superiorly with a high-speed diamond bit drill and a Kerrison rongeur. On the side where the tumor extends into the CS, the bone is care-fully removed from the anterior wall of the CS. A carotid Doppler is used to methodically map out the ICA in rela-tion to the anterior CS wall. After doppler verification of ICA position, the anterior wall of the CS is opened using a right-angled feather blade at the lowest and medial aspect of the anterior wall where the ICA bends posteriorly to form the posterior genu. Low-flow venous bleeding can be easily controlled with light packing with Floseal.Under direct visual control of the ICA, the anterior CS wall is largely opened in a lateral direction and superior direction parallel to the medial wall of the CS to provide adequate visualization of the CS contents and remove tumor off the inferior compartment (Fig. 2B and C). The IPL is frequently visualized at this level and easily dissected and cut. Once the tumor is visualized, a systematic dissection is performed to define its limits and separe it from the ICA and medial wall of the CS. The tumor in the medial and inferior compartment is removed progressively. During dissection the PPL and SPL are visualized, dissected, coagulated and sectioned so as the tumor can be mobilized from the medial surface of the cavernous ICA opening up the superior and posterior compartment of the CS (Fig. 2D) [10]. Tumor can be dissected off these two compartments paying attention to the inferior hypophyseal artery, which usually courses across the base of the posterior clinoid. This last, if neces-sary, can be coagulated and sharply cut to avoid avulsion. The final ligamentous attachments tethering the medial wall and the tumor to the roof of the CS is CCL, which is cut after being coagulated using sharp dissection. Final hemo-stasis is achieved, autologous fat, previously harvested at the abdominal level, is placed at the level of the resection lodge so as to avoid exposure of the ICA (Fig. 3).Fig. 1 Case involving a 62-year-old patient with abnormal IGF levels (745 µg/L) and acromegalic features. (A and B) Pre-operative Gd-enhanced T1W sagittal and coronal MR images showing a pituitary macroadenoma invading the inferior (green arrow), medial, superior (orange arrow) and posterior (red arrow) compartments of the right cavernous sinus. Pituitary gland (red star) is slightly displaced to the left side 1 3  273  Page 2 of 5Acta NeurochirurgicaIndicationSurgery is the main treatment for most functional pitu-itary adenoma with oncologic control in 60–90% of cases depending on published series [8]. Invasion of the CS is one of the limiting factors for total resection for PitNet tumors with cure rates less than 30% [8]. Extended approaches may be considered in selective and well-studied cases of secret-ing adenomas and only in tertiary centers.LimitationsIn the case of extension to the level of the lateral compart-ment of the CS or with invasion of its roof which prevents a total resection [9], the benefit of partial resection of the intracavernous component must be rationally weighed. The presence of interventional radiology are mandatory.Fig. 2 (A) Intraoperative view showing the wide exposure of the ante-rior wall of the cavernous sinus that is prominent due to the lesion. (B) Schematic representation of the sequence of dural cuts for opening the anterior wall of the cavernous sinus. The anterior wall is opened at the lowest and medial aspect of the anterior wall where the carotid bends posteriorly to form the posterior genu. It is, subsequently, largely opened in a superior direction parallel to the medial wall of the CS and lateral direction. (C) intraoperative view showing the compartments of the CS after complete tumor resection. (D) Schematic representation of the inferior (IPL) and superior (SPL) parasellar ligaments and the carotid-clinoid ligament (CCL) 1 3Page 3 of 5   273 Acta NeurochirurgicaSpecific information to give to the patient about surgery and potential risksResection of the intracavernous tumor and the medial wall of the CS is associated with disease remission in nearly 95% of cases [4, 7] of functioning PitNet. However, this tech-nique has an increased risk of nerve injury (4.8% of cases) and potential risk of carotid injury [2], which is why the risk-benefit balance must be rigorously evaluated and dis-cussed with the patient. The preoperative and postoperative management of patients operated on for a pituitary lesion was detailed recently in one of our papers [3].10 key points summary1. Extended approaches may be considered in selective and well-studied cases of secreting adenomas and only in tertiary centers.2. A detailed knowledge of CS anatomy and familiarity with this surgical approach acquired in the laboratory is essential.3. For tumors projecting predominantly to one side of the sella and extending into the CS, a proper planning of surgical access (contralateral vs. transpterygoid) is criti-cal to access the anterior wall of the CS without ana-tomic restrictions and in a direct manner.4. To access the anterior wall of the CS a wide sphenoid-otomy is performed and the sellar bone is removed from CS to CS and from the sellar floor inferiorly to the tuberculum sella superiorly to allow for the necessary lateral exposure without restrictions.5. Proper instrumentation is critical to decrease the risks of vascular injury. This includes a surgical navigation system, a carotid Doppler and a scalpel with blunt-tip blade to dissect the anatomic plane between the medial wall of the CS and the ICA and excise the parasellar ligaments.6. A carotid Doppler is critical for methodically mapping out the ICA in relation to the anterior CS wall.7. The anterior wall of the CS is opened using a right-angled feather blade at the lowest and medial aspect of the anterior wall where the ICA bends posteriorly to form the posterior genu.8. The inferior hypophyseal artery must be identified dur-ing dissection so as to avoid its avulsion during tumor resection.9. The presence of an interventional neuroradiologist is mandatory given the potential risk of vascular injury.10. Autologous fat or pediculated flap is placed at the level of the resection lodge so as to avoid exposure of the ICA.How to avoid complications ● A detailed knowledge of CS anatomy and familiarity with this surgical approach acquired in the laboratory is essential. ● The anatomical location of the sixth cranial nerve within the CS and its relationship to the ICA should always be kept in mind during tumor resection. ● Meticulous preoperative study of the radiologic anato-my of the tumor and its relationship to the CS and ICA is essential. ● Proper planning of surgical access (contralateral vs. transpterygoid) is critical to access the anterior wall of the CS without anatomic restrictions and in a direct manner. ● Proper instrumentation is critical to decrease the risks of vascular injury. This includes a surgical navigation system, a scalpel with blunt-tip blade to dissect the ana-tomic plane between the medial wall of the CS and the ICA and excise the parasellar ligaments. ● The combined use of excellent anatomic knowledge, intraoperative Doppler, and neuronavigation togeth-er represent the best strategy to minimize the risk of complications. ● The use of microdoppler is essential to locate the exact position of the cavernous ICA. ● it is important to obtain adequate venous control for proper visualization.Fig. 3 Post-operative T1W coronal MR image showing the placement of autologous fat in the resection lodge covering the carotid artery 1 3  273  Page 4 of 5Acta Neurochirurgica2. Cossu G, Atkins T, Hajdu SD, Puccinelli F, Daniel RT, Messerer M (2020) Hemorrhagic direct traumatic carotid-cavernous fistula during endoscopic transsphenoidal surgery: intraoperative man-agement and endovascular treatment. Neurosurg Focus Video 2:V1. https://doi.org/10.3171/2020.4.FocusVid.199183. Cossu G, Belouaer A, Kloeckner J, Caliman C, Agri F, Daniel RT, Gaudet JG, Papadakis GE, Messerer M (2023) The enhanced recovery after surgery protocol for the perioperative management of pituitary neuroendocrine tumors/pituitary adenomas. Neuro-surg Focus 55:E9. https://doi.org/10.3171/2023.9.FOCUS235294. de Macedo Filho LJM, Diogenes AVG, Barreto EG, Pahwa B, Samson SL, Chaichana K, Quinones-Hinojosa A, Almeida JP (2022) Endoscopic endonasal resection of the Medial Wall of the cavernous sinus and its impact on outcomes of pituitary surgery: a systematic review and Meta-analysis. Brain Sci 12. https://doi.org/10.3390/brainsci121013545. Fernandez-Miranda JC, Zwagerman NT, Abhinav K, Lieber S, Wang EW, Snyderman CH, Gardner PA (2018) Cavernous sinus compartments from the endoscopic endonasal approach: ana-tomical considerations and surgical relevance to adenoma sur-gery. J Neurosurg 129:430–441. https://doi.org/10.3171/2017.2.JNS1622146. Messerer M, Cossu G, Daniel RT (2019) Endoscopic approach for a delayed post-traumatic ethmoidal mucocele: a technical note. Br J Neurosurg 33:107–109. https://doi.org/10.1080/02688697.2017.12977707. Mohyeldin A, Katznelson LJ, Hoffman AR, Asmaro K, Ahmadian SS, Eltobgy MM, Nayak JV, Patel ZM, Hwang PH, Fernandez-Miranda JC (2022) Prospective intraoperative and histologic evaluation of cavernous sinus medial wall inva-sion by pituitary adenomas and its implications for acromegaly remission outcomes. Sci Rep 12:9919. https://doi.org/10.1038/s41598-022-12980-18. Starnoni D, Daniel RT, Marino L, Pitteloud N, Levivier M, Messerer M (2016) Surgical treatment of acromegaly accord-ing to the 2010 remission criteria: systematic review and meta-analysis. Acta Neurochir (Wien) 158:2109–2121. https://doi.org/10.1007/s00701-016-2903-49. Starnoni D, Cossu G, Messerer M, Daniel RT (2022) Transcavern-ous Approach to the Anteromedial Triangle for residual functional pituitary adenoma. J Neurol Surg B Skull Base 83:e630–e631. https://doi.org/10.1055/s-0041-172711910. Truong HQ, Lieber S, Najera E, Alves-Belo JT, Gardner PA, Fernandez-Miranda JC (2018) The medial wall of the cavernous sinus. Part 1: Surgical anatomy, ligaments, and surgical technique for its mobilization and/or resection. J Neurosurg 131:122–130. https://doi.org/10.3171/2018.3.JNS18596Publisher’s Note Springer Nature remains neutral with regard to juris-dictional claims in published maps and institutional affiliations. Supplementary Information The online version contains supplementary material available at https://doi.org/10.1007/s00701-024-06168-x.Funding No funding was received for this research.Open access funding provided by University of LausanneDeclarationsEthical approval All procedures performed in studies involving human participants were in accordance with the ethical standards of the lo-cal Ethical Committee (Geneva Ethics Committee Board no. 11-233R, NAC 11-085R) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.Informed consent For this type of study formal consent is not required.Conflict of interest All authors certify that they have no affiliations with or involvement in any organization or entity with any financial in-terest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing ar-rangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.Open Access  This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.References1. Berhouma M, Messerer M, Jouanneau E (2012) Occam’s razor in minimally invasive pituitary surgery: tailoring the endoscopic endonasal uninostril trans-sphenoidal approach to sella turcica. Acta Neurochir (Wien) 154:2257–2265. https://doi.org/10.1007/s00701-012-1510-21 3Page 5 of 5   273 

Endoscopic transcavernous approach for functional pituitary adenomas.

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Endoscopic transcavernous approach for functional pituitary adenomas.

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