Open-door extended endoscopic transorbital technique to the paramedian anterior and middle cranial fossae: technical notes, anatomomorphometric quantitative analysis, and illustrative case.

OBJECTIVE: The superior eyelid endoscopic transorbital approach (SETOA) provides a direct and short minimally invasive route to the anterior and middle skull base. Nevertheless, it uses a narrow corridor that limits its angles of attack. The aim of this study was to evaluate the feasibility and potential benefits of an "extended" conservative variant of the "standard" endoscopic transorbital approach-termed "open-door"-to enhance the exposure of lesions affecting the paramedian aspect of the anterior and middle cranial fossae. METHODS: First, the authors described the technical nuances of the open-door extended transorbital approach (ODETA). Next, they documented its morphometric advantages over standard SETOA. Finally, they provided a clinical-anatomical application to demonstrate enhanced exposure and better angles of attack to treat lesions occupying the paramedian anterior and middle cranial fossae. Five adult cadaveric specimens (10 sides) initially underwent standard SETOA and then extended open-door SETOA (ODETA to the paramedian anterior and middle fossae). The adjunct of hinge-orbitotomy, through three surgical steps and straddling the frontozygomatic suture, converted conventional SETOA to its extended open-door variant. CT scans were performed before dissection and uploaded to the neuronavigation system for quantitative analysis. The angles of attack on the axial plane that addressed four key landmarks, namely the tip of the anterior clinoid process (ACP), foramen rotundum (FR), foramen ovale (FO), and trigeminal impression (TI), were calculated for both operative techniques and compared. RESULTS: Hinge-orbitotomy of the extended open-door SETOA resulted in several surgical, functional, and esthetic advantages: it provided wider axial angles of attack for each of the target points, with a gain angle of 26.68° ± 1.31° for addressing the ACP (p < 0.001), 29.50° ± 2.46° for addressing the FR (p < 0.001), 19.86° ± 1.98° for addressing the FO (p < 0.001), and 17.44° ± 2.21° for addressing the lateral aspect of the TI (p < 0.001), while hiding the skin scar, avoiding temporalis muscle dissection, preserving flap vascularization, and decreasing the rate of bone infection and degree of orbital content retraction. CONCLUSIONS: The extended open-door technique may be specifically suited for selected patients affected by paramedian anterior and middle fossae lesions, with prevalent anteromedial extension toward the anterior clinoid, the foremost compartment of the cavernous sinus and FR and not completely controlled with the pure endoscopic transorbital approach.

The Sellar Region as Seen from Transcranial and Endonasal Perspectives: Exploring Bony Landmarks Through New Surface Photorealistic Three-Dimensional Model Reconstruction for Neurosurgical Anatomy Training.

BACKGROUND: Virtual reality-based learning of neuroanatomy is a new feasible method to explore, visualize, and dissect interactively complex anatomic regions. We provide a new interactive photorealistic three-dimensional (3D) model of sellar region microsurgical anatomy that allows side-by-side views of exocranial and endocranial surfaces to be explored, with the aim of assisting young neurosurgery residents in learning microsurgical anatomy of this complex region. METHODS: Four head specimens underwent an endoscopic endonasal approach extended to the anterior and posterior skull base to expose the main bony anatomic landmarks of the sellar region. The same bony structures were exposed from a transcranial perspective. By using a photogrammetry method, multiple photographs from both endocranial and exocranial perspectives, different for angulations and depth, were captured, fused, and processed through dedicated software. RESULTS: All relevant bony structures were clearly distinguishable in the 3D model reconstruction, which provides several benefits in neuroanatomy learning: first, it replicates bony structures with high degrees of realism, accuracy, and fidelity; in addition, it provides realistic spatial perception of the depth of the visualized structures and their anatomic relationships; again, the 3D model is interactive and allows a 360° self-guided tour of the reconstructed object, so that the learner can read the bones and their anatomic relationship from all desired points of view. CONCLUSIONS: Detailed knowledge of key surgical landmarks representing keyholes and/or anatomic structures to not violate is mandatory for safer surgery, especially for a complex region such as the skull base. Highly accurate virtual and functional neurosurgical models, such as photogrammetry, can generate a realistic appearance to further improve surgical simulators and learn neuroanatomy.

Decoding the puzzle: A multidisciplinary systematic review of adult brainstem glioma.

Adult brainstem gliomas (BSGs) are a group of rare central nervous system tumors with varying prognoses and controversial standard treatment strategies. To provide an overview of current trends, a systematic review using the PRISMA guidelines, Class of evidence (CE) and strength of recommendation (SR), was conducted. The review identified 27 studies. Surgery was found to have a positive impact on survival, particularly for focal lesions with CE II SR C. Stereotactic image-guided biopsy was recommended when resective surgery was not feasible with CE II and SR B. The role of systemic treatments remains unclear. Eight studies provided molecular biology data. This review gathers crucial literature on diagnosis and management of adult BSGs. It provides evidence-based guidance with updated recommendations for diagnosing and treating, taking into account recent molecular and genetic advancements. The importance of brain biopsy is emphasized to optimize treatment using emerging genetic-molecular findings and explore potential targeted therapies.

Transorbital and supraorbital uniportal multicorridor approach to the orbit, anterior, middle and posterior cranial fossa: Anatomic study.

Introduction: The transorbital route has been proposed for addressing orbital and paramedian skull base lesions. It can be complemented by further marginotomies, as per "extended-transorbital approach" and combined with others ventro-basal approaches featuring the concept of "multiportal surgery". Nevertheless, it cannot address some anatomical regions like the clinoid, carotid bifurcation and the Sylvian fissure. Therefore, we propose a combined transorbital and a supraorbital approach, attainable by a single infra-brow incision, and we called it "Uniportal multicorridor" approach. Research question: The aim of our study is to verify its feasibility and deep anatomical targets through a cadaveric study. Materials and methods: Anatomic dissections were performed at the Laboratory of ICLO Teaching and Research Center (Verona, Italy) on four formalin-fixed cadaveric heads injected with colored neoprene latex (8 sides). A stepwise dissection of the supraorbital and transorbital approaches (with an infra-brow skin incision) to the anterior tentorial incisura, clinoid area, lateral wall of the cavernous sinus, middle temporal fossa, posterior fossa, and Sylvian fissure is described. Results: We analyzed the anatomic areas reached by the transorbital corridor dividing them as follow: lateral wall of the cavernous sinus, middle temporal fossa, posterior fossa, and Sylvian fissure; while the anatomic areas addressed by the supraorbital craniotomy were the clinoid area and the anterior tentorial incisura. Conclusions: The described uniportal multi-corridor approach combines a transorbital corridor and a supraorbital craniotomy, providing a unique intra and extradural control over the anterior, middle, and posterior fossa, tentorial incisura and the Sylvian fissure, via an infra-brow skin incision.

Systematic review of transcranial and endoscopic endonasal approaches for craniopharyngiomas in children: is there an evolution?

OBJECTIVE: The optimal surgical approach for pediatric craniopharyngiomas (CPs) remains a matter of debate, with selection bias classically precluding a fair comparison of outcomes between the transcranial approach (TCA) and endoscopic endonasal approach (EEA). The purpose of this systematic review was to analyze the current role of EEA in the treatment of pediatric CPs and to determine whether, upon expansion of its indications, a comparison with TCA is valid. METHODS: A systematic review of English-language articles published between February 2010 and June 2022 was performed to identify studies in the MEDLINE (PubMed) and Embase databases reporting on the resection of pediatric CPs. Included were articles reporting on pediatric CPs removed through TCA or EEA. Case reports, review articles, and earlier or less comprehensive series by the same center were excluded. Baseline characteristics and outcomes were analyzed. Prediction intervals (PIs), heterogeneity (Q, I2, and τ2 statistics), and publication bias (funnel plot analysis) were assessed. RESULTS: A total of 835 patients underwent TCA (18 articles) and 403 patients underwent EEA (19 articles). Preoperatively, the mean patient age (p = 0.055, PI = 5.05-15.11), visual impairment (p = 0.08, PI = 19.1-90.5, I2 = 80%), and hypothalamic syndrome (p = 0.17, PI = 6.5-52.2, I2 = 62%) did not significantly differ between the EEA and TCA groups. Endocrine deficit (anterior pituitary deficit [p < 0.001, PI = 16.5-92.9, I2 = 81%] and diabetes insipidus [p < 0.001, PI = 6.3-60.6, I2 = 43%]) was more frequent in the EEA group. Hydrocephalus and signs/symptoms of raised intracranial pressure were significantly higher (p < 0.001, PI = 5.2-73.3, I2 = 70% vs p < 0.001, PI = 4.6-73, I2 = 62%, respectively) in the TCA group. Recurrent lesions (p = 0.52, PI = 2.7-87.3, I2 = 13%), tumor size (p = 0.25, PI = 22.1-56.8), third ventricle involvement (p = 0.053, PI = 10.9-81.3, I2 = 69%), and hypothalamic involvement (p = 0.06, PI = 8.5-83.6, I2 = 79%) did not differ significantly between the approaches. EEA was preferred (p = 0.006, PI = 26.8-70.8, I2 = 40%) for sellar-suprasellar CPs, whereas TCA was preferred for purely suprasellar CPs (p = 0.007, PI = 13.5-81.1, I2 = 61%). There was no difference between the approaches for purely intrasellar lesions (p = 0.94, PI = 0-62.7, I2 = 26%). The breadth of PIs, I2 values, and analysis of publication bias showed substantial variability among the pooled data, hindering the possibility of outcome meta-analyses. CONCLUSIONS: With the adoption of extended approaches, the use of EEA became appropriate for a wider spectrum of pediatric CPs, with associated excellent outcomes. Although a fair comparison between outcomes in the EEA and TCA groups was hindered because of the differences in patient populations and tumor subtypes, given the increased versatility of EEA and improved expertise in its use, surgeons can now select the optimal surgical approach based on the unique benefits and drawbacks of each pediatric CP.

Transorbital Exposure of the Internal Carotid Artery: A Detailed Anatomic and Quantitative Roadmap for Safe Successful Surgery.

BACKGROUND AND OBJECTIVES: The superior eyelid endoscopic transorbital approach has rapidly gained popularity among neurosurgeons for its advantages in the treatment, in a minimally invasive fashion, of a large variety of skull base pathologies. In this study, an anatomic description of the internal carotid artery (ICA) is provided to identify risky zones related to lesions that may be approached using this technique. In this framework, a practical roadmap can help the surgeon to avoid potentially life-threatening iatrogenic vascular injuries. METHODS: Eight embalmed adult cadaveric specimens (16 sides) injected with a mixture of red latex and iodinate contrast underwent superior eyelid transorbital endoscopic approach, followed by interdural dissection of the cavernous sinus, extradural anterior clinoidectomy, and anterior petrosectomy, to expose the entire "transorbital" pathway of the ICA. Furthermore, the distance of each segment of the ICA explored by means of the superior eyelid endoscopic transorbital approach was quantitatively analyzed using a neuronavigation system. RESULTS: We exposed 4 distinct ICA segments and named the anatomic window in which they are displayed in accordance with the cavernous sinus triangles distribution of the middle cranial fossa: (1) clinoidal (Dolenc), (2) infratrochlear (Parkinson), (3) anteromedial (Mullan), and (4) petrous (Kawase). Critical anatomy and key surgical landmarks were defined to further identify the main danger zones during the different steps of the approach. CONCLUSION: A detailed knowledge of the reliable surgical landmarks of the course of the ICA as seen through an endoscopic transorbital route and its relationship with the cranial nerves are essential to perform a safe and successful surgery.

Endoscopic transorbital and transcranial multiportal resection of a sphenoorbital meningiomas with custom bone 3D printing reconstruction: Case report.

BACKGROUND: Sphenoorbital meningiomas (SOM) harbor intrinsic features that render their surgical management and the reconstruction of the resulting bony defect overtly challenging. METHODS: A 70-year-old woman, harboring a long-standing left frontotemporal bony swelling conservatively managed, presented with progressive left proptosis. Radiological features were consistent with an en plaque SOM. A one-step multiportal transcranial and endoscopic transorbital approach (TOA) with custom bone three-dimensional (3D) printing reconstruction using polymethylmethacrylate (PMMA) was scheduled. RESULTS: Postoperative functional and aesthetic results were excellent, with proptosis and calvarian deformity resolution. Tumor subtotal resection was achieved. Histopathological diagnosis confirmed a transitional meningioma (WHO grade I). CONCLUSIONS: The endoscopic TOA, isolated or as part of a multiportal strategy, has entered the surgical armamentarium for the treatment of SOMs. A customized PMMA cranioplasty can be considered a possible option for the reconstruction of large bony defects in a one-step fashion.

Analysis of visual impairment score in a series of 48 tuberculum sellae meningiomas operated on via the endoscopic endonasal approach.

OBJECTIVE: Tuberculum sellae meningioma (TSM) represents a complex skull base tumor. The primary goals of surgical treatment are represented by maximal safe resection and visual recovery; therefore, appropriate patient selection is critical to optimize results. In the last 2 decades, the endoscopic endonasal approach (EEA) has appeared as a successful and viable strategy for the management of these tumors. The authors identified preoperative factors associated with extent of resection and visual outcome after EEA for TSM. METHODS: In this retrospective cohort study, the authors analyzed patients who underwent extended endoscopic endonasal surgery for TSM between January 2005 and April 2022 at the Division of Neurosurgery, Università degli Studi di Napoli Federico II, Naples, Italy. Tumor size, vessel encasement, and optic canal involvement were classified according to University of California, San Francisco, score. Visual acuity and visual fields were analyzed according to the visual impairment score (VIS), defined as a four-level classification: grade 1 (VIS 0-25), grade 2 (VIS 26-50), grade 3 (VIS 51-75), and grade 4 (VIS 76-100). Ophthalmological functions were tested preoperatively and during the early postoperative period (within 6 months after surgery) and late postoperative period. RESULTS: A total of 48 patients were enrolled. Forty-one (85.4%) patients experienced blurred vision or visual field defect as a presenting sign. Gross-total resection was achieved in 40 (83.3%), near-total resection in 2 (4.2%), and subtotal resection in 6 (12.5%). Visual defect improved in 82.9% (34/41) of cases, 12.2% (5/41) had no significant changes, and 2.4% (1/41) had worsened visual defect. The mean change in VIS was 42% (95% CI 58.77-31.23). Visual outcome was poorer when preoperative VIS (VIS-pre) was greater than 25 (p = 0.02). Six postoperative CSF leaks occurred (12.5%), and 1 patient (2.1%) required revision surgery. CONCLUSIONS: The EEA is a safe and effective approach for TSM removal, with the advantage of preserving optic apparatus vascularization, and can promote gross-total resection and visual improvement. The authors have defined four categories based on VIS that relate to postoperative outcome: the lower the VIS-pre, the higher the rate of postoperative VIS improvement. This finding may be useful for predicting a patient's visual outcome at the preoperative stage.

Case Report of Indocyanine Green Endoscopy for Intrasellar Pituitary Adenoma Resection.

Indocyanine green (ICG) angiography has become an established technology in many surgical fields, as well as in neurosurgery with the first application of microscope-integrated indocyanine angiography, which dates to 2003.1 More recently we observed the integration of ICG into endoscopic visualization (e-ICG), which resulted in different applications during the endoscopic endonasal approach ranging from evaluation of intranasal flap perfusion to differentiation of pituitary neuroendocrine tumors from normal gland or even as a predictive factor of postoperative visual function after expanded approaches.2-8 A 49-year-old woman was admitted to our hospital after a 1-year history of amenorrhea and radiologic finding of an intrasellar lesion. The clinical picture was compatible with a nonfunctioning pituitary neuroendocrine tumor, and the mass was completely removed by means of an endoscopic endonasal approach with intraoperative use of e-ICG (Video 1). A 25 mg intravenous bolus of ICG was injected immediately after completion of the sphenoid phase of the approach. ICG was visualized with a dedicated ICG-integrated endoscope coupled to an IMAGE1 S camera system set on Chroma enhancement mode. Near-infrared excitation of fluorescence (780-820 nm) was obtained using a D-light P Cold Light Fountain. At follow-up, the patient experienced resolution of her symptoms, without residues or relapses on control magnetic resonance. This case sheds light on some possible applications and advantages of e-ICG, including visualization of internal carotid arteries before the sellar opening, individuation of the pituitary gland, its distinction from the adenomatous tissue, and the possible evaluation of its degree of compression.

Surgeon's Eyes on the Relevant Surgical Target.

The resolution of the naked eye has been a challenge for the neurosurgical endeavor since the very first attempts of cranial surgery, and advances have been achieved over the centuries, driven by a synergism between the application of emerging technology into the surgical environment and the expansion of the capabilities of neurosurgery. The understanding of the principles of the optical properties of lenses by Abbè (1840-1905) led to the introduction of loupes in the surgical practice, increasing the visual performance during macroscopic procedures. Modern neurosurgery began with the possibility of illumination and magnification of the surgical field as provided by the microscope. Pioneering contributions from Donaghy and Yasargil opened the way to the era of minimalism with reduction of operative corridors and surgical trauma through the adoption of the microsurgical technique. Almost at the same time, engineering mirabilia of Hopkins in terms of optics and lenses allowed for introduction of rigid and flexible endoscopes as a viable tool in neurosurgery. Nowadays, neurosurgeons are aware of and confident using effective and modern tools of visualization in their armamentarium. Herein we present a cogent review of the evolution of visualization tools in neurosurgery, with a special glimpse into the current development and future achievements.

Surgical Management of Adult Brainstem Gliomas: A Systematic Review and Meta-Analysis.

The present review aims to investigate the survival and functional outcomes in adult high-grade brainstem gliomas (BGSs) by comparing data from resective surgery and biopsy. MEDLINE, EMBASE and Cochrane Library were screened to conduct a systematic review of the literature, according to the PRISMA statement. Analysis was limited to articles including patients older than 18 years of age and those published from 1990 to September 2022. Case reports, review articles, meta-analyses, abstracts, reports of aggregated data, and reports on multimodal therapy where surgery was not the primary treatment were excluded. The ROBINS-I tool was applied to evaluate the risk of bias. Six studies were ultimately considered for the meta-analysis. The resective group was composed of 213 subjects and the bioptic group comprised 125. The analysis demonstrated a survival benefit in those patients in which an extensive resection was possible (STR HR 0.59 (95% CI 0.42, 0.82)) (GTR HR 0.63 (95% CI 0.43, 0.92)). Although surgical resection is associated with increased survival, the significantly higher complication rate makes it difficult to recommend surgery instead of biopsy for BSGs. Future investigations combining volumetric data and molecular profiles could add important data to better define the proper indication between resection and biopsy.

Endoscopic endonasal pituitary surgery: How we do it. Consensus statement on behalf of the EANS skull base section.

Introduction and research question: The use of an endoscope in skull base surgery provides a panoramic close-up view over the intracranial structures from multiple angles with excellent illumination, thus permitting greater extent of resection of tumors arising at sellar area, mostly represented by PitNet - Pituitary neuroendocrine tumors, with higher likelihood of preserving vital/intact gland tissue. For this refined specialty of neurosurgery, unique skills need to be acquired along a steep learning curve. Material and methods: EANS (European Association of Neurosurgical Societies) skull base section panelists were enrolled and 11 completed the survey: the goal was to provide a consensus statement of the endoscopic endonasal approach for pituitary adenoma surgery. Results: The survey consisted of 44 questions covering demographics data (i.e., academic/non-academic center, case load, years of experience), surgical techniques (i.e., use of neuronavigation, preoperative imaging), and follow-up management. Discussion and conclusions: In this paper we identified a series of tips and tricks at different phases of an endoscopic endonasal pituitary surgery procedure to underline the crucial steps to perform successful surgery and reduce complications: we took in consideration the principles of the surgical technique, the knowledge of the anatomy and its variations, and finally the importance of adjoining specialties experts.

Endoscopic Endonasal Approach for Tuberculum Sellae Meningioma: 2-Dimensional Operative Video.

INDICATIONS CORRIDOR AND LIMITS OF EXPOSURE: Ideal indications for tuberculum sellae meningiomas (TSM) removal through endoscopic endonasal approach (EEA) are midline tumors (<3.5 cm), possibly with no optic canal invasion and no vessels encasement. The EEA is favored by a wide tuberculm sellae (TS) angle and a deep sella at the sphenoid sinus (SS). 1 Adequate removal of paranasal structures provides a wider surgical corridor ensuring exposure at the suprasellar area and safe instruments manuevrability. 2. ANATOMIC ESSENTIALS NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT: The endoscopic transtuberculum transplanum approach allows for wide suprasellar intradural exposure. 3 Removal of the supraoptic recess (SOR) provides further lateral extension over the planum sphenoidale (PS) and proper management of dural involvement at the optic canal. 4. ESSENTIAL STEPS OF THE PROCEDURE: The patients have consented to the procedure. Bone removal starts at the upper sella and TS and is extended anteriorly over the PS and laterally, upon needs, at the SORs. On dural opening, tumor devascularization, dedressing, debulking, and dissection are run. Skull base reconstruction is performed using the 3F technique. 5. PITFALLS/AVOIDANCE OF COMPLICATIONS: In those cases with vessel encasement, possibility of achieving total resection has to be balanced with risk of vascular injury. 6 Optic canal dural invasion precludes tumor total removal; however, bony decompression is maximal using the EEA. Concerning postoperative cerebrospinal fluid fistula, nowadays the rates have dropped to <2%. VARIANTS AND INDICATIONS FOR THEIR USE: A wider skull base osteodural opening allows for the removal of selected meningiomas extending to the PS and cribriform plate.

Endoscopic transorbital resection of the temporal lobe: anatomic qualitative and quantitative study.

Objective: Starting from an anatomic study describing the possibility of reaching the temporal region through an endoscopic transorbital approach, many clinical reports have now demonstrated the applicability of this strategy when dealing with intra-axial lesions. The study aimed to provide both a qualitative anatomic description of the temporal region, as seen through a transorbital perspective, and a quantitative analysis of the amount of temporal lobe resection achievable via this route. Material and methods: A total of four cadaveric heads (eight sides) were dissected at the Laboratory of Surgical Neuroanatomy (LSNA) of the University of Barcelona, Spain. A stepwise description of the resection of the temporal lobe through a transorbital perspective is provided. Qualitative anatomical descriptions and quantitative analysis of the amount of the resection were evaluated by means of pre- and post-dissection CT and MRI scans, and three-dimensional reconstructions were made by means of BrainLab®Software. Results: The transorbital route gives easy access to the temporal region, without the need for extensive bone removal. The resection of the temporal lobe proceeded in a subpial fashion, mimicking what happens in a surgical scenario. According to our quantitative analysis, the mean volume removed was 51.26%, with the most superior and lateral portion of the temporal lobe being the most difficult to reach. Conclusion: This anatomic study provides qualitative and quantitative details about the resection of the temporal lobe via an endoscopic transorbital approach. Our results showed that the resection of more than half of the temporal lobe is possible through this surgical corridor. While the anterior, inferior, and mesial portions of the temporal lobe were easily accessible, the most superior and lateral segment was more difficult to reach and resect. Our study serves as an integration to the current anatomic knowledge and clinical practice knowledge highlighting and also as a starting point for further anatomic studies addressing more selected segments of the temporal lobe, i.e., the mesial temporal region.

Surgical Approaches to the Third Ventricle: An Update.

The third ventricle is located in the deepest part of the brain and is delimited by both telencephalic and diencephalic structures. Its location makes every surgical procedure inside or around it quite challenging, due to the distance from the surface to the fragility of the neurovascular structures that is necessary to dissect before entering its cavity and to the narrow surgical corridors through which it is necessary to work. Its geometric localization inside the cranial cavity and the anatomical relationship with the interhemispheric fissure offers nevertheless to the surgeon an impressive variety of surgical approaches, which allow to reach every millimeter of the third ventricle lumen. Mastering properly all these approaches requires an impressive anatomical knowledge, the best available technology, and most refined technical skills, making the surgery of the third ventricle a point of excellence in the evolution of each neurosurgeon. The development of neuronavigation and neuroendoscopy has been a revolution in neurosurgery in the last 20 years and offered special advantages for the surgery of the third ventricle. In fact, the narrow corridors of approach make the precision of the neuronavigation and the enlightenment and magnification of the neuroendoscopy especially useful to reach the third ventricle cavity and working inside or around it. This chapter reviews the history of the surgery of the third ventricle and offers an update of the variety of surgical corridors identified and of the technology now available to properly work through them and inside the third ventricle cavity.

A New Perspective on the Cavernous Sinus as Seen through Multiple Surgical Corridors: Anatomical Study Comparing the Transorbital, Endonasal, and Transcranial Routes and the Relative Coterminous Spatial Regions.

Background: The cavernous sinus (CS) is a highly vulnerable anatomical space, mainly due to the neurovascular structures that it contains; therefore, a detailed knowledge of its anatomy is mandatory for surgical unlocking. In this study, we compared the anatomy of this region from different endoscopic and microsurgical operative corridors, further focusing on the corresponding anatomic landmarks encountered along these routes. Furthermore, we tried to define the safe entry zones to this venous space from these three different operative corridors, and to provide indications regarding the optimal approach according to the lesion's location. Methods: Five embalmed and injected adult cadaveric specimens (10 sides) separately underwent dissection and exposure of the CS via superior eyelid endoscopic transorbital (SETOA), extended endoscopic endonasal transsphenoidal-transethmoidal (EEEA), and microsurgical transcranial fronto-temporo-orbito-zygomatic (FTOZ) approaches. The anatomical landmarks and the content of this venous space were described and compared from these surgical perspectives. Results: The oculomotor triangle can be clearly exposed only by the FTOZ approach. Unlike EEEA, for the exposure of the clinoid triangle content, the anterior clinoid process removal is required for FTOZ and SETOA. The supra- and infratrochlear as well as the anteromedial and anterolateral triangles can be exposed by all three corridors. The most recently introduced SETOA allowed for the exposure of the entire lateral wall of the CS without entering its neurovascular structures and part of the posterior wall; furthermore, thanks to its anteroposterior trajectory, it allowed for the disclosure of the posterior ascending segment of the cavernous ICA with the related sympathetic plexus through the Mullan's triangle, in a minimally invasive fashion. Through the anterolateral triangle, the transorbital corridor allowed us to expose the lateral 180 degrees of the Vidian nerve and artery in the homonymous canal, the anterolateral aspect of the lacerum segment of the ICA at the transition zone from the petrous horizontal to the ascending posterior cavernous segment, surrounded by the carotid sympathetic plexus, and the medial Meckel's cave. Conclusions: Different regions of the cavernous sinus are better exposed by different surgical corridors. The relationship of the tumor with cranial nerves in the lateral wall guides the selection of the approach to cavernous sinus lesions. The transorbital endoscopic approach can be considered to be a safe and minimally invasive complementary surgical corridor to the well-established transcranial and endoscopic endonasal routes for the exposure of selected lesions of the cavernous sinus. Nevertheless, peer knowledge of the anatomy and a surgical learning curve are required.

The anterolateral triangle as window on the foramen lacerum from transorbital corridor: anatomical study and technical nuances.

OBJECTIVE: Neurosurgical indications for the superior eyelid transorbital endoscopic approach (SETOA) are rapidly expanding over the last years. Nevertheless, as any new technique, a detailed knowledge of the anatomy of the surgical target area, the operative corridor, and the specific surgical landmark from this different perspective is required for a safest and successful surgery. Therefore, the aim of this study is to provide, through anatomical dissections, a detailed investigation of the surgical anatomy revealed by SETOA via anterolateral triangle of the middle cranial fossa. We also sought to define the relevant surgical landmarks of this operative corridor. METHODS: Eight embalmed and injected adult cadaveric specimens (16 sides) underwent dissection and exposure of the cavernous sinus and middle cranial fossa via superior eyelid endoscopic transorbital approach. The anterolateral triangle was opened and its content exposed. An extended endoscopic endonasal trans-clival approach (EEEA) with exposure of the cavernous sinus content and skeletonization of the paraclival and parasellar segments of the internal carotid artery (ICA) was also performed, and the anterolateral triangle was exposed. Measurements of the surface area of this triangle from both surgical corridors were calculated in three head specimens using coordinates of its borders under image-guide navigation. RESULTS: The drilling of the anterolateral triangle via SETOA unfolds a space that can be divided by the course of the vidian nerve into two windows, a wider "supravidian" and a narrower "infravidian," which reveal different anatomical corridors: a "medial supravidian" and a "lateral supravidian," divided by the lacerum segment of the ICA, leading to the lower clivus, and to the medial aspect of the Meckel's cave and terminal part of the horizontal petrous ICA, respectively. The infravidian corridor leads medially into the sphenoid sinus. The arithmetic means of the accessible surface area of the anterolateral triangle were 45.48 ± 3.31 and 42.32 ± 2.17 mm2 through transorbital approach and endonasal approach, respectively. CONCLUSION: SETOA can be considered a minimally invasive route complementary to the extended endoscopic endonasal approach to the anteromedial aspect of the Meckel's cave and the foramen lacerum. The lateral loop of the trigeminal nerve represents a reliable surgical landmark to localize the lacerum segment of the ICA from this corridor. Nevertheless, as any new technique, a learning curve is needed, and the clinical feasibility should be proven.

The "chameleon" sellar lesions: a case report of unexpected sellar lesions.

Introduction: The sellar region and its boundaries represent a challenging area, harboring a variety of tissues of different linings. Therefore, a variety of diseases can arise or involve in this area (i.e., neoplastic or not). A total of three challenging cases of "chameleon" sellar lesions treated via EEA were described, and the lesions mimicked radiological features of common sellar masses such as craniopharyngiomas and/or pituitary adenomas, and we also report a literature review of similar cases. Methods: A retrospective analysis of three primary cases was conducted at the Università degli Studi di Napoli Federico II, Naples, Italy. Clinical information, radiological examinations, and pathology reports were illustrated. Results: A total of three cases of so-called "chameleon" sellar lesions comprising two men and one woman were reported. Based on the intraoperative finding and pathological examination, we noticed that case 1 had suprasellar glioblastoma, case 2 had a primary neuroendocrine tumor, and case 3 had cavernous malformation. Conclusion: Neurosurgeons should consider "unexpected" lesions of the sellar/suprasellar region in the preoperative differential diagnosis. A multidisciplinary approach with the collaboration of neurosurgeons, neuroradiologists, and pathologists plays a fundamental role. The recognition of unusual sellar lesions can help surgeons with better preoperative planning; so an endoscopic endonasal approach may represent a valid surgical technique to obtain decompression of the optic apparatus and vascular structures and finally a pathological diagnosis.

The feasibility of three port endonasal, transorbital, and sublabial approach to the petroclival region: neurosurgical audit and multiportal anatomic quantitative investigation.

PURPOSE: The petroclival region represents the "Achille's heel" for the neurosurgeons. Many ventral endoscopic routes to this region, mainly performed as isolated, have been described. The aim of the present study is to verify the feasibility of a modular, combined, multiportal approach to the petroclival region to overcome the limits of a single approach, in terms of exposure and working areas, brain retraction and manipulation of neurovascular structures. METHODS: Four cadaver heads (8 sides) underwent endoscopic endonasal transclival, transorbital superior eyelid and contralateral sublabial transmaxillary-Caldwell-Luc approaches, to the petroclival region. CT scans were obtained before and after each approach to rigorously separate the contribution of each osteotomy and subsequentially to build a comprehensive 3D model of the progressively enlarged working area after each step. RESULTS: The addition of the contralateral transmaxillary and transorbital corridors to the extended endoscopic endonasal transclival in a combined multiportal approach provides complementary paramedian trajectories to overcome the natural barrier represented by the parasellar and paraclival segments of the internal carotid artery, resulting in significantly greater area of exposure than a pure endonasal midline route (8,77 cm2 and 11,14 cm2 vs 4,68 cm2 and 5,83cm2, extradural and intradural, respectively). CONCLUSION: The use of different endoscopic "head-on" trajectories can be combined in a wider multiportal extended approach to improve the ventral route to the most inaccessible petroclival regions. Finally, by combining these approaches and reiterating the importance of multiportal strategy, we quantitatively demonstrate the possibility to reach "far away" paramedian petroclival targets while preserving the neurovascular structures.