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

Endoscopic transorbital approach for the management of spheno-orbital meningiomas: A systematic review and meta-analysis

INTRODUCTION

Meningioma is the most common benign tumor in the central nervous system and may arise from the sphenoid wing region. The tumor can involve the cavernous sinus medially, periorbital and orbital apex structures anteriorly, and infratemporal fossa inferiorly. Surgical approaches more currently used include the fronto-temporal approach, the pterional approach, and even the frontotemporal-orbitozygomatic approach. The results of safety and efficacy of Transorbital neuroendoscopic surgery for these cases are still unclear, with scarce literature on the subject.

OBJECTIVE

We assessed the safety and efficacy of Endoscopic Transorbital Approach (TOA) for the Management of Spheno-Orbital Meningiomas (SOMs).

METHODS

We searched Medline, Embase, Web of Science databases following PRISMA guidelines. We used single proportion analysis with 95% confidence intervals under a random-effects model, I2 to assess heterogeneity, and Baujat and sensitivity analysis to address high heterogeneity. Eligible studies included those with ≥4 patients treated with endoscopic transorbital approach for the management of spheno-orbital meningioma.

RESULTS

Of the 3520 studies initially identified, 9 were selected, involving 216 patients, with a median follow-up of 20 months. For subtotal resection, pooled analysis confirmed a rate of 40% (CI: 24% to 57%) and a total resection rate of 46% (CI: 27% to 65%). The analysis also confirmed a rate of visual deficits of 10% (CI: 0% to 24%). The rate of cerebrospinal fluid leak was 2% (CI: 0% to 5%), and diplopia occurred in 8% of cases (CI: 0% to 18%).

CONCLUSION

ETOA is a safe and minimally invasive approach for spheno-orbital meningiomas, with low complication rates and effective cranial nerve preservation. However, its tumor resection efficacy is inferior to non-minimally invasive techniques, potentially affecting long-term outcomes. Further studies are needed to clarify its role and optimize tumor control in selected cases.

Surgical risk of CSF leakage following endoscopic transorbital approach for anterior and middle skull base pathologies: a systematic review and meta-analysis

The endoscopic superior eyelid transorbital approach (SETOA) has demonstrated considerable versatility and effectiveness in managing various paramedian anterior and middle skull base pathologies. However, as with any relatively new technique, potential complications remain. We conducted an extensive literature search in MEDLINE and Embase in accordance with PRISMA guidelines including case reports and surgical series reporting cerebrospinal fluid (CSF) leak rate following SETOA for intracranial pathologies. Factors analyzed included lesion location (extra- or intra-axial), reconstruction techniques, and complication management. ROBINS-I tool was employed to assess the risk of bias. Twenty-five studies including 240 cases were eligible. The majority of lesions were intradural extra-axial (68.3%), while trigeminal schwannomas comprised all extradural cases (25.0%). Sixteen patients (6.6%) presented intradural intra-axial tumors. Osteodural reconstruction involved dural substitutes in one third of the cases (32.5%) either alone (14.2%) or combined with fat free graft (18.3%). CSF leak occurred in 6 patients (2.50%), mostly resolving via conservative management (66.6%). The risk of postoperative CSF leak was found to be significantly higher in patients undergoing resection for intra-axial tumors (OR 0.13, 95% CI: 0.04-0.49) compared to those undergoing resection for extra-axial (OR 0.01, 95% CI: 0.00-0.02; I2 = 0%; p < 0.001). Key limitations include the retrospective nature and small sample sizes among included studies as well as data heterogeneity and lack of standardized protocols for reconstruction across studies. SETOA appears safe for addressing selected extradural and intradural skull base pathologies with a low postoperative CSF leak rate. The natural repositioning of the orbital content to its original position may be instrumental in preventing its postoperative occurrence. The investigation followed a prespecified protocol registered on PROSPERO (PROSPERO 2024 CRD42024614111).

Navigating the Intersection Between the Orbit and the Skull Base: The "Mirror" McCarty Keyhole During Transorbital Approach: An Anatomic Study With Surgical Implications

BACKGROUND AND OBJECTIVES

McCarty keyhole (MCK) is the most important entry point during orbitocranial and cranio-orbital approaches; nevertheless, its anatomic coordinates have never been detailedly described from transorbital perspective. To provide the spatial coordinates for intraorbital projection of the "mirror" MCK by using the well-established main anatomic-surgical bony landmarks met along transorbital corridor.

METHODS

MCK was identified in 15 adult dry skulls (30 sides) on exocranial surface of pterional region based on the well-defined external bony landmarks: on the frontosphenoid suture, 5 to 6 mm behind the joining point (JP) of frontozygomatic suture (FZS), frontosphenoid suture (FSS), and sphenozygomatic suture (SZS). A 1-mm burr hole was performed and progressively enlarged to identify the intracranial and intraorbital compartments. Exit site of the intraorbital part of burr hole was referenced to the FZS on the orbital rim, the superior orbital fissure, and the inferior orbital fissure and to the JP of FZS, FSS, and SZS. To electronically validate the results, 3-dimensional photorealistic and interactive models were reconstructed with photogrammetry. Finally, for a further validation, McCarty mirror keyhole was also exposed, based on results achieved, through endoscopic transorbital approach in 10 head specimens (20 sides).

RESULTS

Intraorbital projection of MCK was identified on the FSS on intraorbital surface, 1.5 ± 0.5 mm posterior to JP, 11.5 ± 1.1 mm posterior to the FZS on orbital rim following the suture, 13.0 ± 1.2 mm from most anterior end of superior orbital fissure, 15.5 ± 1.4 mm from the most anterior end of the inferior orbital fissure in vertical line, on measurements under direct macroscopic visualization (mean ± SD). These values were electronically confirmed on the photogrammetric models with mean difference within 1 mm.

CONCLUSION

To be aware of exact position of intraorbital projection of MCK during an early stage of transorbital approaches provides several surgical, clinical, and aesthetic advantages.

Biportal Endoscopic TransOrbital and transMaxillary Approach to the Cranio-Orbital Region and Middle Cranial Fossa: A Preliminary Analysis of Maneuverability

BACKGROUND AND OBJECTIVES

Traditional and well-established transcranial approaches to the spheno-orbital region and middle cranial fossa guarantee optimal intracranial exposure, and additional orbital and zygomatic osteotomies provide further control over extracranial components to be resected; however, these techniques come at the cost of additional morbidity. The introduction of minimally invasive endoscopic approaches and the conceptualization of the so-called "multiportal" paradigm might provide an alternative route. This preliminary study investigates the feasibility of the combined Biportal Endoscopic TransOrbital and transMaxillary Approach (bETOMA) approach to the spheno-orbital and middle cranial fossa regions.

METHODS

Using 4 silicon-injected adult cadaver heads (8 sides; 16 approaches), we systematically dissected through superior eyelid ETOA and endoscopic TMA approaches. The analysis focused on pterygopalatine, infratemporal, anterior and middle cranial fossae, Meckel cave, and cavernous sinus access. We evaluated the feasibility of bETOMA using linear distances, angles of attack, and exposure areas. We also introduced volume of operative maneuverability, its standardized derivative (sVOM), target distance, visuo-operative angle, and working zone volume as novel metrics.

RESULTS

The analysis revealed comparable angles of attack between approaches. ETOA and TMA exposure areas were 918.38 ± 223.93 mm 2 and 257.07 ± 86.07 mm 2 , respectively. TMA showed a larger VOM in the greater sphenoid wing, but ETOA offered superior distal maneuverability (sVOM: 5.39 ± 1.94 vs 2.54 ± 0.79 cm 3 ) and closer intracranial space access (27.45 vs 50.83 mm). The combined approaches yielded a mean working zone volume of 13.75 ± 3.73 cm 3 in the spheno-orbital interface.

CONCLUSION

The bETOMA approach provides adequate neurovascular exposure and maneuverability to the spheno-orbital region, infratemporal, and anterior and middle cranial fossae, addressing significant limitations of previously investigated monoportal techniques (ie, optic nerve decompression, hyperostotic bone resection, and infratemporal exposure). This combined minimally invasive approach might help manage lesions harbored within the cranio-orbital interface region invading the extracranial space.

Advantages and limitations of orbital rim resection in transorbital endoscopic approach: an anatomical study

BACKGROUND

Endoscopic transorbital approach (eTOA) has been recently proposed as an alternative skull base approach. However, its feasibility for deeper lesions can be hampered by a reduced surgical maneuverability. Aim of this study is to consider how its extension through orbital rim resection can overcome this limitation, and to compare two different techniques for its removal.

METHODS

Both sides of seven cadaveric fresh frozen head were dissected. Three different surgical approaches were performed consequentially (standard eTOA, its expansion with lateral orbital rim hinge removal, and with its complete resection). Distance to target and angle of attack have been measured for superior orbital fissure (SOF), lateral wall of cavernous sinus (LWCS), anterior clinoid process (ACP), foramen rotudum (FR) and foramen ovale (FO).

RESULTS

The angle of attack to the SOF (p = 0.01), to the LWCS (p = 0.001), to the ACP (p = 0.01), to the FR (p = 0.01) and to FO (p = 0.01) resulted larger in extended approaches with orbital rim resection, as well as the distance to target of LWCS (p = 0.04). Particularly, we observed that hinge lateral orbital rim removal improved the angle of attack to SOF (p = 0.02), APC (p = 0.01), FR (p = 0.01 and FO (p = 0.01) in comparison to the standard eTOA.

CONCLUSION

Our study confirms that the lateral orbital rim resection could significantly expand the surgical room and the instruments maneuverability for the considered target skull base targets. Its hinge removal could balance the clinical outcome with the increase of the angles of attack for the more medial and deeper structures.

Assessing the Feasibility of Selective Piezoelectric Osteotomy in Transorbital Approach to the Middle Cranial Fossa: Anatomical and Quantitative Study and Surgical Implications

OBJECTIVE

To verify the feasibility and discuss advantages and disadvantages of a piezoelectric orbitotomy during superior eyelid endoscopic transorbital approach (SETOA). An illustrative case demonstrating the application of this novel technique is also presented.

METHODS

Exoscopic/endoscopic SETOA to middle cranial fossa was performed on 5 adult specimens. The surgical corridor was created via piezoelectric orbitotomy by performing 3 selective and safe micrometric bone cuts providing a 1-piece trapezoid bone flap, which was repositioned and secured at the end of the procedure. A three-dimensional scan of the bone flap allowed us to reconstruct a three-dimensional model and calculate its volume.

RESULTS

Anatomical-morphometric quantitative analysis showed a mean bone volume gain of 1574.26 mm3 by using piezoelectric orbitotomy. Piezoelectric orbitotomy also yielded concrete surgical advantages and theoretical benefits in terms of functional and esthetic outcomes. All osteotomies were micrometric clear-cut and precise, resulting in a very thin bone gap; complete sparing of soft tissues and neurovascular structures in and around the orbit was observed. Lateral orbital wall reconstruction by replacing the bone flap was performed to mitigate the risk of enophthalmos, proptosis, cerebrospinal leakage, pseudomeningocele, and pulsatile headache, which represent significant challenges.

CONCLUSIONS

Piezoelectric orbitotomy may offer a viable, selective, effective, safe alternative to high-speed drilling during SETOA, especially for patients with intra-axial pathologies, in which a watertight closure is mandatory. This procedure could prevent or decrease the risk of some of the main postoperative complications associated with standard SETOA, potentially resulting in better functional and esthetic outcomes.

Biphenotypic Sinonasal Sarcoma with Orbital Invasion: A Literature Review and Modular System of Surgical Approaches

Background: Biphenotypic sinonasal sarcoma is a rare low-grade tumor arising from the sinonasal tract, featuring locally aggressive biological behavior, with a tendency to invade the orbit and skull base. There are no defined guidelines of treatment; thus, the management varies among different institutions. The aim of the present study is to provide a modular system of surgical approaches according to the lesion pattern of growth from a literature review. Materials and Methods: A comprehensive and detailed literature review on the PubMed and Embase online electronic databases on biphenotypic sinonasal sarcoma with orbital invasion was conducted. A personal case exhibiting peculiar features was also added. Demographic (patient's sex and age), clinical (presenting symptoms and time to treatment), neuroradiological (anatomical origin and pattern of growth), and treatment (type of treatment, surgical approach, extent of resection, peri- and postoperative complications, and adjuvant therapies) data, as well as clinical outcome, recurrence rates, and overall survival, were analyzed. Results: Thirty-one patients harboring biphenotypic sinonasal sarcoma with orbital invasion were identified. Tumors mainly affected female patients (66.7%) and a middle-aged population (median 55.2 years old). Simultaneous skull base involvement occurred in most cases (80.6%). Surgery was performed in all but one case (97%), as unique treatment (59%) or in association with radio-(23.5%) and/or chemotherapy (5.9%/2.9%), allowing for gross total tumor resection in most cases (66.7%). The endoscopic endonasal approach was the most adopted surgical corridor (51.7%). The local recurrence rate was 19.3%, and only two cases of tumor-related mortality occurred. Conclusions: Surgery is the only curative treatment, with the main goal to restore/improve/arrest progression of clinical manifestations. The endoscopic endonasal route represents the master approach for lesions confined to the midline. Microsurgical transcranial and endoscopic transorbital approaches have a complementary role for addressing the lesion's component with large intracranial extension or affecting the paramedian aspect of the anterior cranial fossa and superior-lateral orbital compartment, respectively. The approach selection should be made case by case according to the tumor pattern of growth.

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.