Endoscopic transorbital route to the cavernous sinus through the meningo-orbital band: a descriptive anatomical study

The meningo-orbital band from an endoscopic transorbital approach: an anatomical study

Introduction

The meningo-orbital band (MOB) is an intricate dural structure extending between the periorbita, the frontal dura, and the temporal dura. The endoscopic transorbital approach (ETOA) provides a more thorough understanding of its anatomy.

Materials and methods

Anatomical dissections were performed on 15 human head specimens (30 orbits) at the Laboratory of Surgical Neuroanatomy (LSNA) at the University of Barcelona. The specimens were preserved using a Cambridge solution for optimal fixation. An endoscopic transorbital approach (ETOA) was used to isolate the meningo-orbital band (MOB). A rigid 4-mm endoscope with an HD camera and light source was used for the procedure. Multislice helical CT scans were performed both before and after the dissections to document the anatomical features. Additionally, a specialized software (The ImagingSource®) was used to calculate the variability in the angle between the first two bone pillars of the ETOA: the sagittal crest (SC) and the lesser sphenoid wing (LSW). The vascularization of the MOB was studied by longitudinally cutting the band and using red and blue latex injections into the carotid arteries and jugular veins, respectively, to highlight the cerebral vasculature.

Results

In the endoscopic transorbital approach (ETOA), key structures, including the greater and lesser sphenoid wings, are excised, exposing the meningo-orbital band (MOB). The MOB extends from the periorbita medially to the frontal and temporal dura laterally and is firmly attached to the anterior clinoid process (ACP). Anatomical dissection reveals the MOB's complex three-dimensional structure and its relationships with cranial nerves III, IV, and V1 along the lateral wall of the cavernous sinus and the superior orbital fissure (SOF). The ACP serves as a protective barrier between the MOB and the paraclinoid segment of the internal carotid artery (ICA). Additionally, the MOB is vascularized by the MOB artery (MOBA), a branch of the middle meningeal artery, which bifurcates into the frontal and temporal branches.

Conclusion

This study highlights the key anatomical relationships of the meningo-orbital band (MOB) with critical structures, including cranial nerves III, IV, and V1, as well as the ICA. These findings are essential for refining surgical planning and improving the safety and precision of skull base surgery.

Transorbital Approach to the Cavernous Sinus After an Exenteration

BACKGROUND AND OBJECTIVES

To describe a novel technique of transorbital access to the lateral wall of the cavernous sinus (CS) after exenteration.

METHODS

Cadaveric dissection study. Seven heads (13 orbits) were dissected after total orbital exenteration. The technique was centered on creation of an osteotomy within the greater wing of sphenoid, bordered by the superior and inferior orbital fissures to access the middle cranial fossa. V2 within the foramen rotundum was used as a guide to enter the interdural plane of the lateral CS wall. Results were expressed as the mean value ±1 SD.

RESULTS

The lateral CS wall was precisely visualized with identification of cranial nerves III to V2 back to the anterior portion of the Gasserian ganglion. To enable this level of exposure, the osteotomy created within the greater wing of sphenoid was a triangular window with a height of 12.7 ± 1.5 mm (range 10.0-15.0 mm), bordered superiorly by the superior orbital fissure to a linear dimension of 12.8 ± 2.5 mm (range 8.0-18.0 mm), and inferiorly by the inferior orbital fissure to an extent of 12.1 ± 3.9 mm (range 0.9-15.0 mm). The distances from the orbital apex to the intracavernous cranial nerves V1 and V2, and V3 within the foramen ovale were 22.9 ± 3.6 mm (range 17.0-31.0 mm), 25.2 ± 5.0 mm (range 17.5-36.0 mm), and 27.8 ± 5.9 mm (range 18.0-41.0 mm), respectively. The distance between the orbital apex and anterior Gasserian ganglion approximated the maximum surgical corridor achieved with this technique, which was 31.8 ± 4.8 mm (range 26.0-44.0 mm).

CONCLUSION

The transorbital approach to the lateral CS wall is a feasible corridor of access after exenteration. It provides an alternative interdural pathway, thereby obviating the need for additional transcranial or endonasal access routes. Such a technique is in its infancy and surgical series are required to verify it in the clinical setting.

Graded Eyelid Crease Approach to the Superior Orbital Apex: An Anatomical Study

PURPOSE

To describe a graded eyelid crease approach to access the superior orbital apex, and to quantify the working space enabled with the sequential release of structures along the superior orbital rim.

METHODS

Cadaveric dissection study of 7 cadaver heads (14 orbits). This technique involved a subperiosteal approach to the superior orbital apex. This was performed by sequential dissection from 1) the supraorbital neurovascular bundle (SNB) to the zygomaticofrontal suture, 2) extension of this plane to the Whitnall's tubercle, 3a) dissection around the SNB up to the trochlea while preserving the SNB, or 3b) release and division of the SNB, and finally 4) subperiosteal release of the trochlea. Measurements were taken between each landmark (mean ± 1 SD). With each step, a silicone mold was created of the subperiosteal cavity with maximal orbital retraction, which was maintained within 10 mm from the superior orbital rim. The length (mm), width (mm), height (mm), and weight (g) of the mold were quantified.

RESULTS

The mean distance from SNB to the zygomaticofrontal suture is 27.0 ± 2.9 mm; zygomaticofrontal suture to Whitnall's tubercle 8.9 ± 3.1 mm, and SNB to trochlea 4.6 ± 2.7 mm. There was a linear increase in the length, width, and height of the silicone mold with each progressive step. The largest gains in height and weight of the silicone mold were noted progressing from step 2 to 3a.

CONCLUSION

Quantitative analysis of the transorbital approach to the superior orbital apex demonstrates that dissection around the SNB provides a wider surgical corridor of access.

Deep Temporal Muscle Pedicled Flap: A Novel Reconstruction Technique Following Transorbital Approach, Anatomic Study, and Surgical Implications

BACKGROUND AND OBJECTIVES

The temporalis muscle flap has historically been used for repairing defects from orbital procedures and is commonly used in cranial, oral, and facial reconstructions. However, its application for reconstructing the skull base after a transorbital approach has not been explored. Reconstruction after a transorbital intradural approach is still object of preclinical and clinical investigation, with various techniques emerging recently. This study introduces a novel method suitable for extensive resections of the skull base, including intradural resections of the anterior, middle, and posterior cranial fossae.The study aimed to investigate the feasibility of rotating a vascularized myofascial flap from the anterior third of the temporalis muscle onto the skull base, exploring its extension into the middle cranial fossa after drilling the greater wing of the sphenoid.

METHODS

Six endoscopic dissections were performed on formalin-fixed heads to illustrate the feasibility of preparing a deep fascia flap from the temporalis muscle. Red silicone latex was injected into the external carotid artery to confirm the vascular integrity of the deep temporal branches of the maxillary artery.

RESULTS

The deep temporalis myofascial flap offers a large, well-vascularized tissue that can be easily rotated to cover skull base defects after transorbital approaches. Its coverage extends from the middle and anterior cranial fossae to the infratemporal fossa and the lateral wall of the cavernous sinus. It also effectively covers dural defects at the temporal pole.

CONCLUSION

With an appropriate temporal bony window and sufficient exposure, it is feasible to endoscopically prepare a rotation flap from the anterior third of the temporalis muscle, minimizing the need for resecting the lateral orbital margin. This approach is a favorable alternative to traditional reconstruction techniques, offering quick setup in a single operative procedure. Future studies are needed to confirm minimal donor site morbidity regarding masticatory function.

Expanding horizons: the feasibility and challenges of tubular retraction in endoscopic transorbital skull base approaches

PURPOSE

Endoscopic transorbital skull base approaches are always challenging and require good anatomical knowledge.The aim of this study was to describe the anatomical pathways of endoscopic transorbital approaches and to determine the limitations of these procedures. To evaluate the feasibility of the tubular retractor and the difference with manual retractor.

METHODS

The targets of endoscopic transorbital approach were the anterior and middle cranial fossa, mesial temporal region, meckel's cave, petroclival area, opticocarotid region, anterior and lateral walls of the cavernous sinus, etc. Step-by-step anatomical dissections were performed in cadaveric heads using manual and tubular retractors.

RESULTS

Anterior and middle cranial fossa was reached. The branches of the trigeminal nerve, the lateral wall of the cavernous sinus, meckel's cave and gasserian ganglion were exposed by manual and tubular retraction using an endoscopic transorbital approach. Access to the temporal horn of the lateral ventricle and the mesial temporal region was more accessible with a tubular retractor. Also, following the anterior clinoidectomy, the cavernous segment of the internal carotid artery, as well as, the arteries of the anterior circulation were exposed to gain access the vascular skull base lesions.

CONCLUSION

The endoscopic transorbital approach is suitable for the surgical treatment of many pathologies located in the anterior and middle skull base. It provides direct access to vascular and tumoral lesions. We observed that mesial temporal region interventions are possible with this approach. The transtubular technique may have some limitations, but in selected cases it can provide clear vision without brain retraction.

Analysis of Risk Factors and Development of a Prediction Model for Intraoperative Cerebrospinal Fluid Leakage During Transsphenoidal Pituitary Adenoma Surgery

OBJECTIVE

Cerebrospinal fluid (CSF) leakage may occur during transsphenoidal resection of pituitary adenomas, with implications for patient prognosis. However, although the risk factors for intraoperative CSF leakage have been widely studied and continuously explored, there are still some unknown factors that play a role.

METHODS

A retrospective study was conducted by collecting clinical data from 281 patients who underwent transsphenoidal resection of pituitary adenoma at Nanjing Drum Tower Hospital between October 2020 and October 2022.

RESULTS

The results showed CSF leakage occurred in 60 (21.4%) patients. In the univariate analysis, we found that tumor anteroposterior diameter (p = 0.024), hepatic insufficiency (p = 0.004), tough tumor texture (p < 0.001), and surgical protocol as complete removal (p = 0.01) significantly predicted the occurrence of CSF leakage. In the univariate analysis, we found that anteroposterior diameter was associated with the occurrence of intraoperative CSF leakage compared with another diameter (p = 0.04), indicating that the probability of CSF leakage significantly increased at the anteroposterior diameter of pituitary adenoma ≥2 cm. We included anteroposterior tumor diameter, hepatic insufficiency, complete removal, and tumor tough texture together in a multifactorial logistic regression analysis and produced a nomogram graph based on the results. In the multifactorial logistic regression analysis, the anteroposterior tumor diameter, tumor tough texture, hepatic insufficiency, and the surgical option of complete removal predicted intraoperative CSF leakage with an AUC of 0.804.

CONCLUSIONS

This provides a reference for assessing the risk of CSF leakage in patients before and early in the surgical procedure and may have clinical implications for better patient treatments.

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.

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.

Endoscopic-assisted transorbital extended orbital exenteration: A multi-institutional preclinical study

BACKGROUND

Sinonasal malignancies with orbital invasion have dismal prognosis even when treated with orbital exenteration (OE). Sugawara et al. developed a surgical strategy called "extended-OE (EOE)," showing encouraging outcomes. We hypothesized that a similar resection is achievable under endoscopic guidance through the exenterated orbit (endoscopic-EOE).

METHODS

The study was conducted in three institutions: University of Vienna; Mayo Clinic; University of Insubria; 48 orbital dissections were performed. A questionnaire was developed to evaluate feasibility and safety of each step, scoring from 1 to 10, ("impossible" to "easy," and "high risk" to "low risk," respectively), most likely complication(s) were hypothesized.

RESULTS

The step-by-step technique is thoroughly described. The questionnaire was answered by 25 anterior skull base surgeons from six countries. Mean, median, range, and interquartile range of both feasibility and safety scores are reported.

CONCLUSIONS

Endoscopic-EOE is a challenging but feasible procedure. Clinical validation is required to assess real-life outcomes.

The tortuous course of the anterior ethmoidal artery in the orbit: A cadaveric study

AIM

The study aimed to define the coursing pattern of the anterior ethmoidal artery (AEA) in the orbit to minimize complications during endoscopic interventions.

MATERIALS AND METHODS

A total of ten formalin-fixed cadaveric halves were included in the study. Orbital regions were shown with a superior approach. The superior rectus and superior oblique muscles, as well as the connective tissue and vessels were removed to observe the path of the anterior ethmoidal artery. Measurements such as the width of the artery, the anterior-posterior length of the U formation, the length of the intraorbital part of the ophthalmic artery, and the distance of the AEA from its opthalmic origin to the anterior ethmoidal foramen were made.

RESULTS

Ten of the AEAs originated from the ophthalmic artery. The AEA branches originated from the ophthalmic artery approximately 18.4 mm after the orbital artery entered the orbital, and the mean width of the AEAs was 0.82 mm. In seven of the total anterior ethmoidal arteries, they coursed in the intraethmoidal cavities below the cranial base. The mean distance from the origin of AEAs to the medial wall of the orbit was 4.9 mm. After leaving the ophthalmic artery, seven of the AEAs were coursing forward and turned back ('U' turn formation), which have proximately 1.5 mm in anteroposterior direction.

CONCLUSION

The anterior ethmoidal artery is 0.8 mm wide, originates from the distal part of the ophthalmic artery, entering the orbit after a 1.5 mm U-turn.

Transorbital approach to the cavernous sinus: an anatomical study of the related cranial nerves

Background

The cavernous sinus (CS) is a demanding surgical territory, given its deep location and the involvement of multiple neurovascular structures. Subjected to recurrent discussion on the optimal surgical access, the endoscopic transorbital approach has been recently proposed as a feasible route for selected lesions in the lateral CS. Still, for this technique to safely evolve and consolidate, a comprehensive anatomical description of involved cranial nerves, dural ligaments, and arterial relations is needed.

Objective

Detailed anatomical description of the CS, the course of III, IV, VI, and V cranial nerves, and C3-C7 segments of the carotid artery, all described from the ventrolateral endoscopic transorbital perspective.

Methods

Five embalmed human cadaveric heads (10 sides) were dissected. An endoscopic transorbital approach with lateral orbital rim removal, anterior clinoidectomy, and petrosectomy was performed. The course of the upper cranial nerves was followed from their apparent origin in the brainstem, through the middle fossa or cavernous sinus, and up to their entrance to the orbit. Neuronavigation was used to follow the course of the nerves and to measure their length of surgical exposure.

Results

The transorbital approach allowed us to visualize the lateral wall of the CS, with cranial nerves III, IV, V1-3, and VI. Anterior clinoidectomy and opening of the frontal dura and the oculomotor triangle revealed the complete course of the III nerve, an average of 37 (±2) mm in length. Opening the trigeminal pore and cutting the tentorium permitted to follow the IV nerve from its course around the cerebral peduncle up to the orbit, an average of 54 (±4) mm. Opening the infratrochlear triangle revealed the VI nerve intracavernously and under Gruber's ligament, and the extended petrosectomy allowed us to see its cisternal portion (27 ± 6 mm). The trigeminal root was completely visible and so were its three branches (46 ± 2, 34 ± 3, and 31 ± 1 mm, respectively).

Conclusion

Comprehensive anatomic knowledge and extensive surgical expertise are required when addressing the CS. The transorbital corridor exposes most of the cisternal and the complete cavernous course of involved cranial nerves. This anatomical article helps understanding relations of neural, vascular, and dural structures involved in the CS approach, essential to culminating the learning process of transorbital surgery.

Endoscopic transorbital decompression for traumatic superior orbital fissure syndrome: from cadaveric study to clinical application

PURPOSE

The endoscopic endonasal approach (EEA) is a minimally invasive and promising modality for treating traumatic superior orbital fissure (SOF) syndrome (tSOFS). Recently, the endoscopic transorbital approach (ETOA) has been considered an alternative method for reaching the anterolateral skull base. This study accessed the practicality of using the ETOA to treat SOF decompression using both cadaveric dissection and clinical application.

METHODS

Bilateral anatomic dissections were performed on four adult cadaveric heads using the ETOA and EEA to address SOF decompression. The ETOA procedure for SOF decompression is described, and the extent of SOF decompression was compared between the ETOA and EEA. The clinical feasibility of the ETOA for treating SOF decompression was performed in two patients diagnosed with tSOFS.

RESULTS

ETOA allowed for decompression over the lateral aspect of the SOF, from the meningo-orbital band superolaterally to the maxillary strut inferomedially. By contrast, the EEA allowed for decompression over the medial aspect of the SOF, from the lateral opticocarotid recess superiorly to the maxillary strut inferiorly. In both patients treated using the ETOA and SOF decompression, the severity of ophthalmoplegia got obvious improvement.

CONCLUSIONS

Based on the cadaveric findings, ETOA provided a feasible access pathway for SOF decompression with reliable outcomes, and our patients confirmed the clinical efficacy of the ETOA for managing tSOFS.

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.

360 Degrees Endoscopic Access to and Through the Orbit

The treatment of pathologies located within and surrounding the orbit poses considerable surgical challenges, due to the intricate presence of critical neurovascular structures in such deep, confined spaces. Historically, transcranial and craniofacial approaches have been widely employed to deal with orbital pathologies. However, recent decades have witnessed the emergence of minimally invasive techniques aimed at reducing morbidity. Among these techniques are the endoscopic endonasal approach and the subsequently developed endoscopic transorbital approach (ETOA), encompassing both endonasal and transpalpebral approaches. These innovative methods not only facilitate the management of intraorbital lesions but also offer access to deep-seated lesions within the anterior, middle, and posterior cranial fossa via specific transorbital and endonasal corridors. Contemporary research indicates that ETOAs have demonstrated exceptional outcomes in terms of morbidity rates, cosmetic results, and complication rates. This study aims to provide a comprehensive description of endoscopic-assisted techniques that enable a 360° access to the orbit and its surrounding regions. The investigation will delve into indications, advantages, and limitations associated with different approaches, while also drawing comparisons between endoscopic approaches and traditional microsurgical transcranial approaches.

Transorbital Route to Intracranial Space

The endoscopic superior eyelid transorbital approach has emerged as a notable and increasingly utilized surgical technique in recent years. This chapter presents an overview of the approach, tracing its historical development and highlighting its growing acceptance within the skull base community.Beginning with an introduction and historical perspective, the chapter outlines the evolution of the transorbital approach, shedding light on its origins and the factors driving its adoption. Subsequently, a comprehensive exploration of the anatomic bone pillars and intracranial spaces accessible via this approach is provided. Hence, five bone pillars of the transorbital approach were identified, namely the lesser sphenoid wing, the anterior clinoid, the sagittal crest, the middle cranial fossa, and the petrous apex. A detailed correlation of those bone targets with respective intracranial areas has been reported.Furthermore, the chapter delves into the practical application of the technique through a case example, offering insights into its clinical utility, indications, and limitations.

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.

Tips and tricks for maximising access to the middle cranial fossa using the superior lateral orbital portal

BACKGROUND

Transorbital endoscopic approaches are becoming increasingly popular for skull base pathologies; the superior lateral orbital portal is one such approach to the middle cranial fossa. This paper provides a technical description that maximises the surgical portal and minimises morbidity.

TECHNICAL DESCRIPTION

A superior lid crease incision is made extending laterally and the orbital rim is exposed. A subperiosteal dissection of the lateral and superior orbit is performed, with elevation of periosteum off Whitnall's tubercle, ligation of the recurrent branch of the middle meningeal artery, and identification of the superior orbital fissure. The lacrimal keyhole is then drilled away. The middle cranial fossa is accessed by drilling posterior to the orbital rim to expose: the temporalis muscle anterior-laterally, the dura of the temporal lobe posterior-laterally, the anterior cranial fossa superiorly and the periorbita medially.

CONCLUSION

These surgical steps can maximise the surgical portal and minimise morbidity, with avoidance of injury to surrounding structures.

The Transorbital Approach, A Game-Changer in Neurosurgery: A Guide to Safe and Reliable Surgery Based on Anatomical Principles

During the last few years, the superior eyelid endoscopic transorbital approach has been proposed as a new minimally invasive pathway to access skull base lesions, mostly in ophthalmologic, otolaryngologic, and maxillofacial surgeries. However, most neurosurgeons performing minimally invasive endoscopic neurosurgery do not usually employ the orbit as a surgical corridor. The authors undertook this technical and anatomical study to contribute a neurosurgical perspective, exploring the different possibilities of this novel route. Ten dissections were performed on ten formalin-fixed specimens to further refine the transorbital technique. As part of the study, the authors also report an illustrative transorbital surgery case to further detail key surgical landmarks. Herein, we would like to discuss equipment, key anatomical landmarks, and surgical skills and stress the steps and details to ensure a safe and successful procedure. We believe it could be critical to promote and encourage the neurosurgical community to overcome difficulties and ensure a successful surgery by following these key recommendations.

Surgical Anatomy of the Microscopic and Endoscopic Transorbital Approach to the Middle Fossa and Cavernous Sinus: Anatomo-Radiological Study with Clinical Applications

BACKGROUND

The transorbital approaches (TOAs) have acquired growing notoriety, thanks to their ability to offer alternative corridors to the skull base. However, the limited access and the unfamiliarity with this surgical perspective make recognition of key landmarks difficult, especially for less experienced surgeons. The study wants to offer a detailed description of the anatomy to comprehend the potential and limitations of TOAs.

METHODS

Measurements of the orbit region and the surrounding areas were performed on two hundred high-resolution CT scans and thirty-nine dry skulls. Five specimens were dissected to illustrate the TOA, and one was used to perform the extradural clinoidectomy. Three clinical cases highlighted the surgical applications.

RESULTS

A step-by-step description of the key steps of the TOA was proposed and a comparison with the transcranial anterior clinoidectomy was discussed. The mean work distance was 6.1 ± 0.4 cm, and the lateral working angle increased 20 ± 5.4° after removing the lateral orbital rim.

CONCLUSIONS

TOAs are indicated in selected cases when tumor involves the lateral portion of the cavernous sinus or the middle skull base, obtaining a direct decompression of the optic nerve and avoiding excessive manipulation of the neurovascular structures. Comprehension of surgical anatomy of the orbit and its surrounding structures is essential to safely perform these approaches.

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.

Transorbital transposition of the temporoparietal fascia flap to reconstruct the skull base defects: A preclinical study with comparison to the transpterygoid transposition

BACKGROUND

Transpterygoid transposition of the temporoparietal fascia flap (TPFF) is a feasible selection for ventral skull base defect (VSBD) reconstruction, but not anterior skull base defect (ASBD) reconstruction, after expanded endoscopic endonasal approach (EEEA). The goal of this study is to introduce the transorbital transposition of the TPFF for skull base defects reconstruction after EEEA, and make quantitative comparison between the transpterygoid transposition and transorbital transposition.

METHODS

Cadaveric dissections were performed in five adult cadaveric heads with creating three transporting corridors bilaterally, encompassing superior transorbital corridor, inferior transorbital corridor, and transpterygoid corridor. For each transporting corridor, the minimum necessary length of the TPFF for skull base defects reconstruction was measured.

RESULTS

The areas of ASBD and VSBD were 1019.63 ± 176.32 mm2 and 572.99 ± 126.21 mm2 . The length of the harvested TPFF was 149.38 ± 6.21 mm. In contrast to the transpterygoid transposition with incomplete coverage, transorbital transposition of the TPFF allowed full coverage of ASBD with a minimum necessary length of 109.75 ± 8.31 mm. For VSBD reconstruction, transorbital transposition of the TPFF needs shorter minimum necessary length (123.88 ± 4.49 mm) than transpterygoid transposition (138.00 ± 6.28 mm).

CONCLUSIONS

Transorbital corridor is a novel pathway for transporting the TPFF into the sinonasal cavity for skull base defects reconstruction after EEEA. In comparison with transpterygoid transposition, transorbital transposition provides wider coverage of skull base defects with a fixed length of the TPFF.

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

Introduction

Orbital surgery has always been disputed among specialists, mainly neurosurgeons, otorhinolaryngologists, maxillofacial surgeons and ophthalmologists. The orbit is a borderland between intra- and extracranial compartments; Krönlein's lateral orbitotomy and the orbitozygomatic infratemporal approach are the historical milestones of modern orbital-cranial surgery.

Research question

Since its first implementation, endoscopy has significantly impacted neurosurgery, changing perspectives and approaches to the skull base. Since its first application in 2009, transorbital endoscopic surgery opened the way for new surgical scenario, previously feasible only with extensive tissue dissection.

Material and methods

A PRISMA based literature search was performed to select the most relevant papers on the topic.

Results

Here, we provide a narrative review on the current state and future trends in endoscopic orbital surgery.

Discussion and conclusion

This manuscript is a joint effort of the EANS frontiers committee in orbital tumors and the EANS skull base section.

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.

Transuncal Selective Amygdalohippocampectomy by an Inferolateral Preseptal Endoscopic Approach Through Inferior Eyelid Conjunctival Incision: An Anatomic Study

BACKGROUND

Transorbital endoscopic approaches have been described for pathologies of anterior and middle fossae. Standard lateral orbitotomy gives access to mesial temporal lobe, but the axis of work is partially obscured by the temporal pole and working corridor is limited.

OBJECTIVE

To evaluate the usefulness of an inferolateral orbitotomy to provide a more direct corridor to perform a transuncal selective amygdalohippocampectomy.

METHODS

Three adult cadaveric specimens were used for a total of 6 dissections. A step-by-step description and illustration of the transuncal corridor for a selective amygdalohippocampectomy were performed using the inferolateral orbitotomy through an inferior eyelid conjunctival incision. The anatomic landmarks were demonstrated in detail. Orbitotomies and angles of work were measured from computed tomography scans, and the area of resection was illustrated by postdissection MRI.

RESULTS

Inferior eyelid conjunctival incision was made for exposure of the inferior orbital rim. Inferolateral transorbital approach was performed to access the transuncal corridor. Endoscopic selective amygdalohippocampectomy was performed through the entorhinal cortex without damage to the temporal neocortex or Meyer's loop. The mean horizontal diameter of the osteotomy was 14.4 mm, and the vertical one was 13.6 mm. The mean angles of work were 65° and 35.5° in the axial and sagittal planes, respectively. Complete amygdalohippocampectomy was achieved in all 6 dissections.

CONCLUSION

Transuncal selective amygdalohippocampectomy was feasible in cadaveric specimens using the inferolateral transorbital endoscopic approach avoiding damage to the temporal neocortex and Meyer's loop. The inferior eyelid conjunctival incision may result in an excellent cosmetic outcome.

Cadaveric analysis of transcranial versus endoscopic transorbital petrosectomy: comparison of surgical maneuverability and brainstem exposure

Introduction

While accessing the posterior fossa, the anterior transpetrosal approach (ATPA) and endoscopic transorbital approach (ETOA) use the same bony landmarks during petrous apex drilling. However, owing to their contrasting surgical axes, they are expected to show differences in surgical view, maneuverability, and clinical implications. This study aimed to investigate the feasibility of ETOA in accessing the brainstem and to compare the surgical view and maneuverability of each approach.

Methods

ATPA and ETOA were performed in four human cadaveric heads (eight sides and four sides in each procedure). The angle of attack (AOA) and surgical depth were measured at the target of interest (root exit zone [REZ] of cranial nerve [CN] V, VI, and VII). When measuring the area of exposure, the brainstem was divided into two areas (anterior and lateral brainstem) based on the longitudinal line crossing the entry zone of the trigeminal root, and the area of each was measured.

Results

ATPA showed significantly greater value at the trigeminal REZ in both vertical (31.8 ± 6.7° vs. 14.3 ± 5.3°, p=0.006) and horizontal AOA (48.5 ± 2.9° vs. 15.0 ± 5.2°, p<0.001) than ETOA. The AOA at facial REZ was also greater in ATPA than ETOA (vertical, 27.5 ± 3.9° vs. 8.3 ± 3.3°, p<0.001; horizontal, 33.8 ± 2.2° vs. 11.8 ± 2.9°, p<0.001). ATPA presented significantly shorter surgical depth (CN V, 5.8 ± 0.5 cm vs. 9.0 ± 0.8, p<0.001; CN VII, 6.3 ± 0.5 cm vs. 9.5 ± 1.0, p=0.001) than ETOA. The mean area of brainstem exposure did not differ between the two approaches. However, ATPA showed significantly better exposure of anterior brainstem than ETOA (240.7 ± 9.6 mm² vs. 171.7 ± 15.0 mm², p<0.001), while ETOA demonstrated better lateral brainstem exposure (174.2 ± 29.1 mm² vs. 231.1 ± 13.6 mm², p=0.022).

Conclusions

ETOA could be a valid surgical option, in selected cases, that provides a direct ventral route to the brainstem. Compared with ATPA, ETOA showed less surgical maneuverability, AOA and longer surgical depth; however, it presented comparable brainstem exposure and better exposure of the lateral brainstem.

TransOrbital NeuroEndoscopic Surgery for Biopsy of the Left Cavernous Sinus: A Literature Review, Case Report, and Cadaveric Proof of Concept

The aim of this report is to describe TransOrbital NeuroEndoscopic Surgery (TONES) as a safe alternative for obtaining a cavernous sinus (CS) biopsy. We describe this technique in a patient with a diffuse large B cell lymphoma mimicking Tolosa-Hunt's syndrome. Articles were gathered querying PubMed, Embase, and Scopus databases with terms related to a "transorbital neuroendoscopic approach." The literature search was performed by two independent authors (N.L.F. and J.R.), with inconsistencies resolved by the senior author (M.M.D.V.). After screening abstracts for relevance, full-length articles were reviewed for pertinent variables. A comparison was conducted with the illustrative case of a 69-year-old woman who presented to the emergency department with vertigo, ophthalmoplegia, and diplopia for 2 months. A brain magnetic resonance imaging revealed an infiltrative lesion at the left CS. A presumptive diagnosis of Tolosa-Hunt syndrome was made, but a confirmatory biopsy was performed using TONES. Based on our cadaveric study, literature review, and case report, the TONES approach was safe, effective for tissue diagnosis, and associated with minor morbidity and reduced hospital stay. Additional prospective studies are required to study its viability and safety in a larger group of patients.

Alternative Path for Optic Nerve Decompression in Pseudotumor Cerebri With Full Endoscopic Lateral Transorbital Approach

Endonasal endoscopic approaches are the most preferred surgical methods in patients with pseudotumor cerebri because of easy access to the optic nerve, but the choice of this technique may not apply to all endoscopic endonasal cases. Moreover, there may be difficulties in practice in some cases, including the coronavirus disease 2019 pandemic. This study aimed to suggest an alternative endoscopic approach by lateral orbitotomy for optic nerve decompression in patients with pseudotumor cerebri. The study was performed using 5 fresh-frozen cadaver heads (bilaterally, total of 10 sides) injected intravenously with colored silicone preserved in the cold chain. An average of 2.5 cm skin incision was made to fit the lateral orbitotomy. The lengths of the recurrent meningeal artery (mm), the meningo-orbital band (mm), and the optic nerve (mm) to the orbital margin were measured. After these morphometric measurements, optic nerve decompression was performed endoscopically, and the length of the decompression was measured (mm). The average length (mm) between the orbital rim and meningeal recurrent artery (or meningolacrimal branch) was 16.2 mm, between the orbital rim and the meningo-orbital band was 18.5 mm, and between the orbital rim and optic nerve was 44.1 mm. The average optic nerve decompression length was 4.4 mm. The endoscopic lateral orbitotomy approach provides easy access to the optic nerve by anatomically following the recurrent meningeal artery and the meningo-orbital band. It can be a safe second-line approach after endonasal approaches for optic nerve decompression in pseudotumor cerebri.

Comparison of Accessibility to Cavernous Sinus Areas Throughout Endonasal, Transorbital, and Transcranial Approaches: Anatomic Study With Quantitative Analysis

BACKGROUND

The cavernous sinus (CS) is accessed through several approaches, both transcranially and endoscopically. The transorbital endoscopic approach is the newest proposed route in the literature.

OBJECTIVE

To quantify and observe the areas of the CS reach from 2 endoscopic and 1 transcranial approaches to the CS in the cadaver laboratory.

METHODS

Six CSs were dissected through endoscopic endonasal, transorbital endoscopic, and transcranial pterional approaches, with previous implanted references for neuronavigation during the dissection. Point registration was used to mark the CS exposure and limits through each approach for later area and volume quantification through a computerized technique.

RESULTS

The endoscopic endonasal approach reaches most of the CS except part of the sinus's superior, lateral, and posterior regions. The area exposed through this approach was 210 mm 2 , and the volume was 1165 mm 3 . The transcranial pterional approach reached the superior and part of the lateral sides of the sinus, not allowing good access to the medial side. The area exposed through this approach was 306 m 2 , whereas the volume was 815 m 3 . Finally, the transorbital endoscopic approach accessed the whole lateral side of the sinus but not the medial one. The area exposed was the greatest, 374 m 2 , but its volume was the smallest, 754 m 3 .

CONCLUSION

According to our results, the endonasal endoscopic approach is the direct route to access the medial, inferior, and part of the superior CS compartments. The transorbital approach is for the lateral side of the CS. Finally, the transcranial pterional approach is the one for the superior side of the CS.

The "Crista Ovale": A Reliable Anatomical Landmark in Transorbital Endoscopic Approaches to the Middle Cranial Fossa

BACKGROUND

Transorbital endoscopic approaches (TOEAs) have emerged as adjunct and alternatives for accessing the middle cranial fossa (MCF). Nuances of the skull base anatomy from a ventral transorbital endoscopic viewpoint remain to be fully described.

OBJECTIVE

To assess the anatomy of the "crista ovale" (COv), described transcranially as the midsubtemporal ridge (MSR), from a ventral transorbital perspective and evaluate its role as a landmark in TOEA to the MCF.

METHODS

Lateral TOEAs to the MCF were performed in 20 adult cadaveric heads (40 sides). The presence of the COv/MSR was evaluated under endoscopic visualization. Anatomic relationships between COv/MSR and surrounding structures were assessed. The presence of COv/MSR was also examined in 30 cadaveric head computed tomography (CT) scans (60 sides).

RESULTS

The COv/MSR was identified in 98% (39/40) of sides at the MCF, as 1 of 4 major configurations. The COv/MSR was found anterolateral to the foramen ovale and foramen spinosum (mean distance: 9.2 ± SD 2.4 mm and 12.3 ± SD 2.6 mm, respectively) directly anterior or anteromedial to the petrous apex (mean distance: 26.2 ± SD 2.6 mm) and at a mean 47.6 ± SD 4.7 mm from the approach's surgical portal. It was recognized in 95% (57/60) of CT scans.

CONCLUSION

The COv/MSR can be readily identified during TOEA to the MCF and on CT. It serves as a reliable landmark to localize the foramen ovale, foramen spinosum, and petrous apex. Further studies may confirm its surgical significance in transorbital endoscopic procedures.

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.

Transorbital drillout to the cavernous sinus: an approach for squamous cell carcinoma with perineural spread. Illustrative cases

BACKGROUND

This study describes a transorbital apical approach to the cavernous sinus, where the greater wing of sphenoid (GWS) and superior orbital fissure (SOF) are drilled out to access the interdural incision zone and lateral wall of the cavernous sinus.

OBSERVATIONS

This was a retrospective series of 3 patients with periocular squamous cell carcinoma (SCC) and radiological evidence of perineural spread to the cavernous sinus. Following an orbital exenteration, the GWS was drilled to reach the lateral border of the SOF. The meningo-orbital band, a periosteal transition between the frontotemporal basal dura and periorbita, was incised to enter the lateral wall of the cavernous sinus. The relevant cranial nerves were biopsied to provide an accurate zonal classification of disease.

LESSONS

The transorbital apical approach via the SOF provides a corridor of access to the cranial nerves within the lateral wall of the cavernous sinus. This technique was successfully performed on 3 patients with periocular SCC. One case had radiological evidence of intracavernous oculomotor nerve involvement, 1 patient demonstrated nasociliary nerve enlargement at the SOF, and another had frontal nerve involvement extending into the cavernous sinus. Cerebrospinal fluid leak occurred in 1 case addressed with fat packing and fascial closure.

Multiportal Combined Endoscopic Endonasal and Transorbital Pathways: Qualitative and Quantitative Anatomic Studies of the "Connection" Skull Base Areas

BACKGROUND

Combined endonasal and transorbital multiportal surgery has been recently described for selected skull base pathologies. Nevertheless, a detailed anatomic description and a quantitative comprehensive anatomic study of the skull base areas where these 2 endoscopic routes converge, a so-called connection areas, are missing in the scientific literature.

OBJECTIVE

To identify all the skull base areas and anatomic structures where endonasal and transorbital endoscopic avenues could be connected and combined.

METHODS

Five cadaveric specimens (10 sides) were used for dissection. Qualitative description and quantitative analysis of each connection areas were performed.

RESULTS

At the anterior cranial fossa, the connection area was found at the level of the sphenoid planum; in the middle cranial fossa, it was at the Mullan triangle; finally, in the posterior cranial fossa, the connection area was just behind the medial portion of the petrous apex. The average extradural working areas through the transorbital approach were 4.93, 12.93, and 1.93 cm 2 and from the endonasal corridor were 7.75, 10.45, and 7.48 cm 2 at the level of anterior, middle, and posterior cranial fossae, respectively.

CONCLUSION

The combined endonasal and transorbital endoscopic approach is an innovative entity of skull base neurosurgery. From the anatomic point of view, our study demonstrated the feasibility of this combined approach to access the entire skull base, by both corridors, identifying a working connection area in each cranial fossa. These data could be extremely useful during the surgical planning to predict which portion of a lesion could be removed through each route and to optimize patients' care.

Functional and clinical outcomes after superior eyelid transorbital endoscopic approach for spheno-orbital meningiomas: illustrative case and literature review

The pattern of growth of spheno-orbital meningiomas accounts for the main presenting symptoms, such as proptosis, eye motility deficit, visual impairment, diplopia. As these are benign tumors, the postoperative patient's quality of life is an important factor to consider during the preoperative planning. A detailed literature review of superior eyelid transorbital endoscopic approach for spheno-orbital meningiomas, including our own case, was made. A Medline search up to March 2022 in PubMed online electronic database was made using the following key phrases: "superior eyelid endoscopic transorbital approach spheno-orbital meningiomas," "superior eyelid endoscopic transorbital approach," "spheno-orbital meningiomas endoscopic approach." The inclusion criteria were surgical series, reviews, and case reports in English language, as well as papers written in other languages, but including the abstract in English. Cadaveric studies, multiportal combined approaches for SOM, were excluded. The literature review has disclosed five studies for a total of 65 patients, whose demographic, clinical, pathological, surgical, complications, and outcome data were analyzed. Functional and esthetic outcome data after superior eyelid transorbital approach are the following: improvement of proptosis (100%), of visual deficits (66.66%) and of ocular paresis (75%), with only 11 complications (4 trigeminal dysesthesia, 2 CSF leak, 2 wound complications, 1 upper eyelid necrosis, 1 hemorrhage of surgical field, 1 keratitis) reported, but at the expense of extent of resection (gross total resection 33.39%). Based on the outcome data, the superior eyelid transorbital endoscopic approach results in a suitable operative technique for selected spheno-orbital meningiomas.

Superior eyelid endoscopic transorbital approach to the tentorial area: A qualitative and quantitative anatomic study

Objective

Superior eyelid endoscopic transorbital approach (SETOA) is nowadays gaining progressive application in neurosurgical scenarios. Both anatomic and clinical reports have demonstrated the possibility of taking advantage of the orbital corridor as a minimally invasive route to reach anterior and middle cranial fossae and manage selected surgical lesions developing in these areas. The aim of this paper is to further shed light on other anatomic regions of the skull base as seen from a transorbital perspective, namely, the posterior cranial fossa and tentorial area, describing technical feasibility and steps in reaching this area through an extradural-transtentorial approach and providing quantitative evaluations of the "working area" obtained through this route.

Material and methods

Four cadaveric heads (eight sides) were dissected at the Laboratory of Surgical Neuroanatomy (LSNA) of the University of Barcelona, Spain. A stepwise dissection of the transorbital approach to the tentorial area was described. Qualitative anatomical descriptions and quantitative analyses of working were evaluated by using pre- and postdissections CT and MRI scans, and three-dimensional reconstructions were made using Amira software.

Results

With the endoscopic transorbital approach, posterior cranial fossa dura was reached by an extradural middle cranial fossa approach and drilling of the petrous apex. After clipping the superior petrosal sinus, the tentorium was divided and cut. An endoscope was then introduced in the posterior cranial fossa at the level of the tentorial incisura. Qualitative analysis provided a description of the tentorial and petrosal surfaces of the cerebellum, middle tentorial incisura, cerebellopontine fissures, and, after arachnoid dissection, by a 30° endoscopic visualization, the posterior aspect of the cerebellomesencephalic fissure. Quantitative analysis of the "working area" obtained after bone removal was also provided.

Conclusions

This anatomic qualitative and quantitative study sheds light on the anatomy of the posterior cranial fossa contents, such as the tentorial area and incisura, as seen through a transorbital perspective. The first aim of the article is to enrich the anatomical knowledge as seen through this relatively new corridor and to provide quantitative details and insights into the technical feasibility of reaching these regions in a surgical scenario.

Clinical analysis of cavernous sinus anatomy, pathologies, diagnostics, surgical management and complications - comprehensive review

For decades, the cavernous sinus (CS) has been the subject of debates and scientific studies aimed at elucidating its anatomical variability, and at choosing the best method for accessing it so that optimal diagnoses and related surgical treatments can be decided. The present review considers a series of issues related to the CS. The anatomy of the CS and its features is explored first, and the most important structures, spaces and morphological variations are considered. This is followed by CS pathology and selected diagnostic methods that have proved useful in therapy, and then the management of these pathologies is discussed. Examples of therapeutic steps that have proved helpful in specific cases are taken from the literature. Finally, the various surgical accesses and complications that can be encountered during invasive interventions in the CS area are discussed. The aim of this study is to summarize up-to-date anatomical and clinical knowledge about the CS, citing the most informative scientific papers and aggregating their results. Morphological variations of the CS are common but have not been well described in the literature.

Endoscopic transorbital avenue to the skull base: Four-step conceptual analysis of the anatomic journey

Background

In the last decades, skull base surgery had passed through an impressive evolution. The role of neuroanatomic research has been uppermost, and it has played a central role in the development of novel techniques directed to the skull base. Indeed, the deep and comprehensive study of skull base anatomy has been one of the keys of success of the endoscopic endonasal approach to the skull base. In the same way, dedicated efforts expended in the anatomic lab has been a powerful force for the growth of the endoscopic transorbital approach to the lateral skull base.

Therefore, in this conceptual paper, the main steps for the anatomic description of the endoscopic transorbital approach to the skull base have been detailed.

Methods

The anatomic journey for the development of the endoscopic transorbital approach to the skull base has been analyzed, and four “conceptual” steps have been highlighted.

Results

As neurosurgeons, the eyeball has always represented a respectful area: to become familiar with this complex and delicate anatomy, we started by examining the orbital anatomy on a dry skull (step 1). Hence, step 1 is represented by a detailed bone study; step 2 is centered on cadaveric dissection; step 3 consists in 3D quantitative assessment of the novel endoscopic transorbital corridor; and finally, step 4 is the translation of the preclinical data in the real surgical scenario by means of dedicated surgical planning.

Conclusions

The conceptual analysis of the anatomic journey for the description of the endoscopic transorbital approach to the skull base resulted in four main methodological steps that should not be thought strictly consequential but rather interconnected. Indeed, such steps should evolve following the drives that can arise in each specific situation. In conclusion, the four-step anatomic rehearsal can be relevant for the description, diffusion, and development of a novel technique in order to facilitate the application of the endoscopic transorbital approach to the skull base in a real surgical scenario.

Endoscopic transorbital approach to the cavernous sinus: Cadaveric anatomy study and clinical application (‡SevEN-009)

Objective

Cavernous sinus (CS) invasion is frequently encountered in the management of skull base tumors. Surgical treatment of tumors in the CS is technically demanding, and selection of an optimal surgical approach is critical for maximal tumor removal and patient safety. We aimed to evaluate the feasibility of an endoscopic transorbital approach (ETOA) to the CS based on a cadaveric study.

Methods

Five cadaveric heads were used for dissection under the ETOA in the comparison with the endoscopic endonasal approach (EEA) and the microscopic transcranial approach (TCA). The CS was exposed, accessed, and explored, first using the ETOA, followed by the EEA and TCA. A dedicated endoscopic system aided by neuronavigation guidance was used for the procedures. During the ETOA, neurovascular structures inside the CS were approached through different surgical triangles.

Results

After completing the ETOA with interdural dissection, the lateral wall of the CS was fully exposed. The lateral and posterior compartments of the CS, of which accessibility is greatly limited under the EEA, were effectively approached and explored under the ETOA. The anteromedial triangle was the largest window via which most of the lateral compartment was freely approached. The internal carotid artery and abducens nerve were also observed through the anteromedial triangle and just behind V1. During the ETOA, the approaching view through the supratrochlear and infratrochlear triangles was more directed towards the posterior compartment. After validation of the feasibility and safety based on the cadaveric study, ETOA was successfully performed in a patient with a pituitary adenoma with extensive CS invasion.

Conclusions

Based on the cadaveric study, we demonstrated that the lateral CS wall was reliably accessed under the ETOA. The lateral and posterior compartments of the CS were effectively explored via surgical triangles under the ETOA. ETOA provides a unique and valuable surgical route to the CS with a promising synergy when used with EEA and TCA. Our experience with a clinical case convinces us of the efficacy of the ETOA during surgical management of skull base tumors with CS-invasion.

Endoscopic-assisted transorbital surgery: Where do we stand on the scott’s parabola? personal considerations after a 10-year experience

Transorbital approaches are genuinely versatile surgical routes which show interesting potentials in skull base surgery. Given their “new” trajectory, they can be a very useful adjunct to traditional routes, even being a valid alternative to them in some cases, and add valuable opportunities in selected patients. Indications are constantly expanding, and currently include selected intraorbital, skull base and even intra-axial lesions, both benign and malignant. Given their relatively recent development and thus unfamiliarity among the skull base community, achieving adequate proficiency needs not only a personalized training and knowledge but also, above all, an adequate case volume and a dedicated setting. Current, but mostly future, applications should be selected by genetic, omics and biological features and applied in the context of a truly multidisciplinary environment.

Extended endoscopic transorbital approach with superior-lateral orbital rim osteotomy: cadaveric feasibility study and clinical implications (SevEN-007)

OBJECTIVE

The endoscopic transorbital approach (ETOA) has been developed, permitting a new surgical corridor. Due to the vertical limitation of the ETOA, some lesions of the anterior cranial fossa are difficult to access. The ETOA with superior-lateral orbital rim (SLOR) osteotomy can achieve surgical freedom of vertical as well as horizontal movement. The purpose of this study was to confirm the feasibility of the ETOA with SLOR osteotomy.

METHODS

Anatomical dissections were performed in 5 cadaveric heads with a neuroendoscope and neuronavigation system. ETOA with SLOR osteotomy was performed on one side of the head, and ETOA with lateral orbital rim (LOR) osteotomy was performed on the other side. After analysis of the results of the cadaveric study, the ETOA with SLOR osteotomy was applied in 6 clinical cases.

RESULTS

The horizontal and vertical movement range through ETOA with SLOR osteotomy (43.8° ± 7.49° and 36.1° ± 3.32°, respectively) was improved over ETOA with LOR osteotomy (31.8° ± 5.49° and 23.3° ± 1.34°, respectively) (p < 0.01). Surgical freedom through ETOA with SLOR osteotomy (6025.1 ± 220.1 mm3) was increased relative to ETOA with LOR osteotomy (4191.3 ± 57.2 mm3) (p < 0.01); these values are expressed as the mean ± SD. Access levels of ETOA with SLOR osteotomy were comfortable, including anterior skull base lesion and superior orbital area. The view range of the endoscope for anterior skull base lesions was increased through ETOA with SLOR osteotomy. After SLOR osteotomy, the space for moving surgical instruments and the endoscope was widened. Anterior clinoidectomy could be achieved successfully using ETOA with SLOR osteotomy. The authors performed ETOA with SLOR osteotomy in 6 cases of brain tumor. In all 6 cases, complete removal of the tumor was successfully accomplished. In the 3 cases of anterior clinoidal meningioma, anterior clinoidectomy was performed easily and safely, and manipulation of the extended dural margin and origin dura mater was possible. There was no complication related to this approach.

CONCLUSIONS

The authors evaluated the clinical feasibility of ETOA with SLOR osteotomy based on a cadaveric study. ETOA with SLOR osteotomy could be applied to more diverse disease groups that do not permit conventional ETOA or to cases in which surgical application is challenging. ETOA with SLOR osteotomy might serve as an opportunity to broaden the indication for the ETOA.

Combined endoscopic endonasal and transorbital multiportal approach for complex skull base lesions involving multiple compartments

PURPOSE

This study defines the specific areas that connect the surgical corridors of the endoscopic endonasal (EEA) and transorbital approach (TOA) to identify adequate clinical applications and perspectives of this combined multiportal approach.

METHODS

Consecutive patients who underwent combined EEA and TOA procedures for various pathologies involving multiple compartments of the skull base were enrolled.

RESULTS

A total of eight patients (2 chondrosarcomas, 2 meningiomas, 2 schwannomas, 1 glioma, and 1 traumatic optic neuropathy) were included between August 2016 and April 2021. The cavernous sinus (CS) was targeted as the connection area of the combined approach in four patients with tumors infiltrating the middle cranial fossa (MCF) and central skull base through the CS. For two patients with MCF tumors extending into the infratemporal fossa (ITF), the horizontal portion of the greater sphenoid wing and the foramen ovale were utilized as the connection area. In the remaining 2 patients, connection was achieved through the optic canal (OC). Gross total and near total resection was achieved in 5 patients with tumors, and circumferential removal of bone composing the OC was performed in one patient with traumatic compressive optic neuropathy. Postoperative complications included one cardiac arrest due to underlying cardiovascular disease and one case of oculomotor nerve palsy.

CONCLUSIONS

The combined EEA and TOA procedure is a useful strategy for complex lesions involving multiple compartments of the skull base. Herein, we identified the specific areas connecting the two surgical approaches, allowing a common path for EEA and TOA procedures.

"Sagittal Crest": Definition, Stepwise Dissection, and Clinical Implications From a Transorbital Perspective

BACKGROUND

The recent development of the superior eyelid endoscopic transorbital approach (SETOA) offered a new route for the management of cavernous sinus and middle cranial fossa tumors. As a result, a constant anatomic landmark of the surgical pathway after drilling the medial edge of the greater sphenoid wing (GSW) is represented by a triangular-shaped bone ridge appearing as a "crest."

OBJECTIVE

To perform an anatomic study to define this surgical landmark, named the "sagittal crest" (SC) as seen from the transorbital endoscopic view.

METHODS

Four adult cadaveric specimens (8 sides) were dissected performing an endoscopic transorbital approach to the middle fossa and the SC was removed to perform interdural opening of the cavernous sinus. Computed tomography scans were made before and after removal of the SC to perform quantitative analysis and building a 3-dimensional model of the bone resection of the GSW via the SETOA.

RESULTS

The SC is a bone ridge triangle shaping dorsally the superior orbital fissure resulting as the residual fragment after drilling the lateral aspect of the greater sphenoid wing. Predissection and postdissection computed tomography scans allowed to objectively assess SC features and dimensions (mean 1.08 ± 0.2 cm).

CONCLUSION

The SC is a constant anatomic landmark constituted of the residual medial portion of the GSW. Complete resection of this key landmark provides adequate working space and appears to be mandatory during SETOA to guide the subsequent interdural dissection of the lateral wall of cavernous sinus.

Endoscopic Transorbital Approach to Mesial Temporal Lobe for Intra-Axial Lesions: Cadaveric Study and Case Series (SevEN-008)

BACKGROUND

Endoscopic transorbital approach (ETOA) has been proposed as a minimally invasive technique for the treatment of skull base lesions located around mesial temporal lobe (MTL), mostly extra-axial pathology.

OBJECTIVE

To explore the feasibility of ETOA in accessing intraparenchymal MTL with cadaveric specimens and describe our initial clinical experience of ETOA for intra-axial lesions in MTL.

METHODS

Anatomic dissections were performed in 4 adult cadaveric heads using a 0° endoscope. First, a stepwise anatomical investigation of ETOA to intraparenchymal MTL was explored. Then, ETOA was applied clinically for 7 patients with intra-axial lesions in MTL, predominantly high-grade gliomas (HGGs) and low-grade gliomas (LGGs).

RESULTS

The extradural stage of ETOA entailed a superior eyelid incision followed by orbital retraction, drilling of orbital roof, greater and lesser wing of sphenoid bone, and cutting of the meningo-orbital band. For the intradural stage, the brain tissue medial to the occipito-temporal gyrus was aspirated until the temporal horn was opened. The structures of MTL could be aspirated selectively in a subpial manner without injury to the neurovascular structures of the ambient and sylvian cisterns, and the lateral neocortex. After cadaveric validation, ETOA was successfully performed for 4 patients with HGGs and 3 patients with LGGs. Gross total resection was achieved in 6 patients (85.7%) without significant surgical morbidities including visual field deficits.

CONCLUSION

ETOA provides a logical line of access for intra-axial lesions in MTL. The safe and natural surgical trajectory of ETOA can spare brain retraction, neurovascular injury, and disruption of the lateral neocortex.

Quantitative Anatomic Comparison of Microsurgical Transcranial, Endoscopic Endonasal, and Transorbital Approaches to the Spheno-Orbital Region

BACKGROUND

The spheno-orbital region (SOR) is a complex anatomic area that can be accessed with different surgical approaches.

OBJECTIVE

To quantitatively compare, in a preclinical setting, microsurgical transcranial approaches (MTAs), endoscopic endonasal transpterygoid approach (EEA), and endoscopic transorbital approaches (ETOAs) to the SOR.

METHODS

These approaches were performed in 5 specimens: EEA, ETOAs (superior eyelid and inferolateral), anterolateral MTAs (supraorbital, minipterional, pterional, pterional-transzygomatic, and frontotemporal-orbitozygomatic), and lateral MTAs (subtemporal and subtemporal transzygomatic). All specimens underwent high-resolution computed tomography; an optic neuronavigation system with dedicated software was used to quantify working volume and exposed area for each approach. Mixed linear models with random intercepts were used for statistical analyses.

RESULTS

Anterolateral MTAs offer a direct route to the greater wings (GWs) and lesser wings (LWs); only they guarantee exposure of the anterior clinoid. Lateral MTAs provide access to a large area corresponding to the GW, up to the superior orbital fissure (SOF) anteriorly and the foramen rotundum medially. ETOAs also access the GW, close to the lateral portion of SOF, but with a different angle of view as compared to lateral MTAs. Access to deep and medial structures, such as the lamina papyracea and the medial SOF, is offered only by EEA, which exposes the LW and GW only to a limited extent.

CONCLUSION

This is the first study that offers a quantitative comparison of the most used approaches to SOR. A detailed knowledge of their advantages and limitations is paramount to choose the ideal one, or their combination, in the clinical setting.

When multidisciplinary surgical trans-orbital approaches should be considered to reach the skull base

The transorbital approaches are a group of surgical procedures performed passing through the orbital spaces and aimed to reach deeper areas. This kind of surgery has been proved to be safe and effective in the management of selected lesions of the anterior, middle and infratemporal fossa. The aim of the present study is to perform a review of the literature, in order to draw the reader’s attention on the main features of this kind of surgery, focusing on the anatomical background and the surgical setting; we will also summary the current indications and contraindications to this approach and find out the related complications and the possible alternatives. Even if we consider the transorbital approach as a promising route to the skull base, we underline that there is no better approach over another and the choice must always consider several elements. Furthermore, as for every skull base procedure, a multidisciplinary management is strongly advisable.

Combined and simultaneous endoscopic endonasal and transorbital surgery for a Meckel's cave schwannoma: technical nuances of a mini-invasive, multiportal approach

OBJECTIVE

Over the years, Meckel's cave pathologies have been judged off-limits because of high rates of morbidity. Even though several studies have defined various surgical routes with tolerable morbidity and mortality rates, controversies related to the optimal avenue to treat different categories of Meckel's cave and cavernous sinus neoplasms persist. With unceasing energy to cultivate minimally invasive neurosurgical approaches, the endoscopic endonasal route has been tested, and the approach effectively performed, to provide a valid surgical window to these areas. In this dynamic and challenging scenario, another ventral endoscopic minimally invasive route-that is, the superior eyelid endoscopic transorbital approach-has been very recently proposed, and used in selected cases, to access the cavernous sinus and Meckel's cave regions.

METHODS

The authors report the technical nuances of a combined and simultaneous endoscopic endonasal and transorbital surgical treatment of a patient with a Meckel's cave schwannoma. The operation involved collaboration among neurosurgery, otorhinolaryngology, and ophthalmology (oculoplastic surgery). The patient recovered well, had no neurological deficits, and was discharged to home 3 days after surgery.

RESULTS

The multiportal combined route was proposed for the following reasons. The endonasal approach, considered to be more familiar to our skull base team, could allow control of possible damage of the internal carotid artery. From the endonasal perspective, the most inferior and medial portion of the tumor could be properly managed. Finally, the transorbital route, by means of opening the lateral wall of the cavernous sinus via the meningoorbital band, could allow control of the superolateral part of the tumor and, most importantly, could permit removal of the portion entering the posterior cranial fossa via the trigeminal pore. Simultaneous surgery with two surgical teams working together was planned in order to reduce operative time, hospital stay, and patient stress and discomfort, and to ensure "one-shot" complete tumor removal, with minimal or no complications.

CONCLUSIONS

This study represents the translation into the real surgical setting of recent anatomical contributions related to the novel endoscopic transorbital approach and its simultaneous integration with the endoscopic endonasal pathway. Accordingly, it may pave the way for future applications related to minimally invasive, multiportal endoscopic surgery for skull base tumors.

A Novel Combined Transorbital Transnasal Endoscopic Approach for Reconstruction of Posttraumatic Complex Anterior Cranial Fossa Defect

The transorbital neuroendoscopic surgery (TONES), endoscopic transnasal skull base procedures, and the concept of multiportal minimal access neurosurgery are novel, rapidly evolving approaches in the management of complex skull base lesions. A 27-year-old male presented with a history of road traffic accident with nasal bleed, cerebrospinal fluid (CSF) rhinorrhea, and left eye deformity. There was left upper eyelid ecchymosis, orbital dystopia, left pupil was dilated, and fixed with no extraocular movements. The computed tomography scan showed basifrontal contusion and complex comminuted anterior cranial fossa (ACF) fracture involving left cribriform plate and left orbital roof with fracture fragment impinging on the superior rectus muscle with suspicious orbital CSF leak. There was no improvement with conservative management. Hence, a novel combined TONES, transnasal endoscopic multiportal surgery was undertaken for the removal of fracture fragments and multi-layered closure of the complex ACF defect. The patient had a complete resolution of orbital dystopia and visual loss with no evidence of CSF leak postoperatively.

Endoscopic transorbital ligation of the maxillary artery through the inferior orbital fissure

OBJECTIVE

Determine the feasibility of accessing the internal maxillary artery (IMA) through a transorbital endoscopic assisted approach through the inferior orbital fissure (IOF).

MATERIALS AND METHODS

Six adult cadaveric specimens were injected intravascularly with colored latex and dissected on 12 sides. A transorbital endoscopic approach was used to expose the IOF and reach the IMA.

RESULTS

The average length and width of the anterolateral segment of the IOF were 7.3 and 4 mm, respectively, on the right side and 6.7 and 3.8 mm, respectively, on the left side. Surgical exposure and modification of the IOF allowed the exposure and control of the IMA in all 12 sides.

CONCLUSIONS

The IOF is a feasible portal to the IMA. The benefits of this approach include vascular control of the distal segment of the maxillary artery. It may provide access in clinical scenarios where endonasal access is not possible (e.g., extensive tumors) or serve as an alternative or complementary surgical route (e.g., control during a total or radical maxillectomy).

Transorbital endoscopic approaches to the skull base: a systematic literature review and anatomical description

Transorbital endoscopic approaches are increasing in popularity as they provide corridors to reach various areas of the ventral skull base through the orbit. They can be used either alone or in combination with different approaches when dealing with the pathologies of the skull base. The objective of the current study is to evaluate the surgical anatomy of transorbital endoscopic approaches by cadaver dissections as well as providing objective clinical data on their actual employment and morbidity through a systematic review of the current literature. Four cadaveric specimens were dissected, and step-by-step dissection of each endoscopic transorbital approach was performed to identify the main anatomic landmarks and corridors. A systematic review with pooled analysis of the current literature from January 2000 to April 2020 was performed and the related studies were analyzed. Main anatomical landmarks are presented based on the anatomical study and systematic review of the literature. With emphasis on the specific transorbital approach used, indications, surgical technique, and complications are reviewed through the systematic review of 42 studies (19 in vivo and 23 anatomical dissections) including 193 patients. In conclusion, transorbital endoscopic approaches are promising and appear as feasible techniques for the surgical treatment of skull base lesions. Surgical anatomy of transorbital endoscopic approaches can be mastered through knowledge of a number of anatomical landmarks. Based on data available in the literature, transorbital endoscopic approaches represent an important complementary that should be included in the armamentarium of a skull base team.