Transorbital Microsurgery: An Anatomical Description of a Minimally Invasive Corridor to the Anterior Cranial Fossa and Paramedian Structures.

Objectives Transorbital neuroendoscopic surgery (TONES) has ignited interest in the transorbital access corridor, increasing its use for single and multi-portal skull base interventions. However, the crowding of a small corridor and two-dimensional viewing restrict this access portal. Design Cadaveric qualitative study to assess the feasibility of transorbital microsurgery (TMS). Setting Anatomical dissection steps and instrumentation were recorded for homogeneous methodology. Participants Six cadaveric specimens were systematically dissected using TMS to the anterior cranial fossa and paramedian structures. Main Outcome Measures Anatomical parameters of the TMS craniectomy were established, and the visible and accessible neuroanatomy was highlighted. Results A superior lid crease incision achieved essential orbital rim exposure and preseptal dissection. The orbital roof craniectomy is defined by three boundaries: (1) frontozygomatic suture to the frontosphenoid suture, (2) frontal sinus and cribriform plate, and (3) frontal sinus and orbital rim. The mean (standard deviation) craniectomy was 440 mm 2 (78 mm 2 ). Exposing the ipsilateral optic nerve and internal carotid artery obviated the need for frontal lobe retraction to identify the A1-M1 bifurcation as well as near-complete visualization of the M1 artery. Conclusion TMS is a feasible corridor for intracranial access. Mobilization of orbital contents is imperative for maximal intracranial access and protection of the globe. TMS enables access to the frontal lobe base, ipsilateral optic nerve, and most of the ipsilateral anterior circulation. This cosmetically satisfactory approach causes minimal destruction of the anterior skull base with satisfactory exposure of the anterior cranial fossa floor without sinus invasion.

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

OBJECTIVES: To verify the feasibility and to discuss advantages and disadvantages of a piezoelectric orbitotomy (PO) during Superior Eyelid Endoscopic Transorbital Approach (SETOA). METHODS: Five adult specimens underwent exoscopic/endoscopic SETOA to middle cranial fossa. The surgical corridor was created via piezoelectric orbitotomy by performing three selective and safe micrometric bone cuts providing a one-piece trapezoid bone flap which was repositioned and secured at the end of procedure. A 3D scan of the bone flap allowed us to reconstruct a 3D model and calculate its volume. An illustrative case demonstrating the application of this novel technique was also presented. RESULTS: Anatomical-morphometric quantitative analysis showed a mean bony-volume gain of 1,574.26 mm3 by using PO. PO 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 bony gap; a complete sparing of soft tissues and neurovascular structures in- and around the orbit was observed. Lateral orbital wall reconstruction by replacing the bone flap aims to mitigate the risk of enophthalmos, proptosis, CSF leakage, pseudomeningocele and pulsatile headache, which represent significant challenges in the relevant literature. CONCLUSION: PO may offer a viable, selective, effective, safe alternative to high-speed drilling during SETOA, especially for patients affected by intra-axial pathologies in which a watertight closure is mandatory. This procedure could prevent/decrease the risk of some of the main postoperative complications associated to the standard SETOA, resulting potentially in better functional and esthetic outcome.

Transorbital Approach Clipping of Middle Cerebral Artery Aneurysm: A Virtual Reality Morphometric Anatomic Study.

BACKGROUND: The transorbital approach (TOA) has a unique advantage to the more common lateral approaches as it provides direct access to the anterior middle fossa and medial sylvian fissure (SF) without significant dissection or retraction. However, when to use the TOA for surgical treatment of middle cerebral artery (MCA) aneurysms remains unclear. This study details the feasibility of clipping unruptured MCA aneurysms via the TOA by highlighting the anatomic features that either facilitate or hinder the approach. METHODS: Virtual reality (VR) models of 25 MCA aneurysms from computed tomography angiograms of actual patients were rendered with the relevant anatomic structures, including the neighboring temporal lobe and SF. TOA was performed on the models in VR and the globe was translated medially and inferiorly, replicating retraction used intraoperatively. Anatomic data, including the area of surgical freedom (AOF) at the aneurysm, were recorded. Trials of aneurysm clipping were conducted in VR and each aneurysm was classified as "possible" or "impossible" candidates for clipping via TOA. Separately, the relationship between surgical view and SF visualized was analyzed. RESULTS: Sixteen aneurysms were eliminated as candidates for TOA treatment either through VR clip trial and/or because the SF was inaccessible. The remaining 9 (36%) were candidates for TOA. Comparing the details of these 2 aneurysm categories with Mann Whitney U tests, there was a statistically significant difference in the AOF of the TOA approach and the width of the aneurysm dome. A clinical case report is also provided highlighting the VR rehearsal similarity with surgery. CONCLUSIONS: Given the minimally invasive, technically challenging approach, the feasibility and safety of TOA for MCA aneurysms must be evaluated before wide clinical adoption. This study identified AOF, aneurysm width, and SF accessibility as three features that may significantly impact the possibility of clipping MCA aneurysms via TOA.

Optimizing Management of Cavernous Sinus Meningiomas: A Novel Strategy Integrating Endoscopic Endonasal and Transorbital Surgery with Adjuvant Stereotactic Radiotherapy.

BACKGROUND: Cavernous sinus meningiomas (CSMs) are challenging skull base tumors due to their proximity to vital neurovascular structures. Traditional aggressive transcranial resection often leads to significant morbidities with limited improvement of cranial nerve (CN) deficits. Recent advancements in endoscopic skull base surgery and stereotactic radiation therapy (SRT) offer a more conservative approach, facilitating tumor decompression while preserving critical structures. METHODS: This retrospective study reviewed medical records of patients with symptomatic CSMs who underwent endoscopic endonasal and/or transorbital surgery, followed by adjuvant SRT, at our institution between January 2017 and April 2022. Patient demographics, tumor characteristics, surgical approaches, radiation, treatment outcomes, complications, and follow-up time were analyzed. RESULTS: Thirty-nine patients with CSMs were included. Endoscopic endonasal approach was performed in 24 patients (61.5%), endoscopic transorbital approach in 10 patients (25.6%), and combined approaches in 5 patients (12.8%). Adjuvant SRT was administered to 79.5% of patients. Postoperative outcomes showed recovery of CN 3-6 deficits and vision in 60.9% and 65% of cases, respectively. Complications included postoperative CN 3-6 deficits in 5 cases and postradiation visual deterioration in 1 case. During a mean follow-up period of 44 months, tumor progression occurred in 4 patients (10.3%), with 3 diagnosed as World Health Organization grade II meningiomas and 1 as World Health Organization grade I. CONCLUSIONS: This study supports the use of endoscopic skull base surgery combined with adjuvant SRT for symptomatic CSMs, demonstrating both safety and efficacy. This approach yielded favorable outcomes in symptom improvement, tumor control, and positive safety profile.

Is It Time for a Paradigm Shift in the Surgical Management of Trigeminal Schwannomas? Evaluating the Role of the Transorbital Approach: An Anatomo-Clinical Study and Systematic Literature Review.

BACKGROUND: Endoscopic transorbital approach emerged in recent years as an effective, minimally invasive route to access Meckel's cave area. Several case series proved its effectiveness in the surgical treatment of trigeminal schwannomas. This route provides the advantages of a minimally invasive approach associated with low morbidity rates. In this anatomo-clinical study we illustrate the usefulness of the superior eyelid transorbital approach for the surgical treatment of trigeminal schwannoma guiding the clinical applicability of the anatomical findings into real surgical practice. METHODS: Superior eyelid transorbital endoscopic approach was performed on 8 cadaveric specimens, and the surgical results were confirmed in a retrospective review of all the surgical cases of transorbital surgery performed by the senior authors providing an illustrative case. Finally, we performed a literature review of all the case series of trigeminal schwannomas operated through an endoscopic transorbital approach. RESULTS: Stepwise dissection was divided in 3 phases: skin, endo-orbital, and endocranial. The illustrative case provided demonstrate gross total resection of a cavernous sinus type trigeminal schwannomas treated through this route. Literature review revealed 68 cases of trigeminal schwannomas that were successfully treated using the transorbital approach. CONCLUSIONS: The endoscopic transorbital approach may offer a valuable alternative for the surgical treatment of trigeminal schwannomas. This technique provides a minimally invasive, direct and natural "interdural" route to the lateral wall of the cavernous sinus and Meckel's cave.

Treating Trigeminal Schwannoma through a Transorbital Approach: A Systematic Review.

Background: Trigeminal schwannomas (TSs) are uncommon tumors found along any segment of the fifth cranial nerve (CN V). Typically located at the skull base, these benign tumors carry substantial morbidity due to the extent of traditional surgical methods. Minimally invasive endoscopic surgery such as the endoscopic transorbital approach (ETOA) presents promising new avenues for treatment, with the transorbital approach emerging as a potentially successful alternative. Methods: This review systematically assesses the application of the ETOA in treating TSs. PubMed, Ovid MEDLINE, and Embase were thoroughly searched for articles detailing the use of the ETOA in clinical case studies. The outcomes of interest encompassed epidemiological profiling, surgical results, and complication rates. Results: This study included 70 patients with TSs (from six studies), with 22 males (31.4%) and 58 females (68.6%). Patients averaged 55 years and were monitored for around 16.4 months (on average). In most tumors, the middle cranial fossa was involved to some degree. The majority (87.2%) were large (3-6 cm) and underwent gross total resection (GTR) or near-total resection in 87.2% of patients. Preoperatively, sensory alterations were common, along with proptosis, neuropathic pain, and diplopia. Postoperatively, complications included ptosis, diplopia, sensory impairment, corneal keratopathy, masticatory difficulty, and neuralgia. The pure ETOA was the primary surgical technique used in 90% of cases, with no recurrence observed during the follow-up period. Conclusions: Using the ETOA to treat TSs demonstrated an oncologic control rate of 87.2%. Postoperative complications including ptosis, diplopia, and sensory disturbances have been observed, but careful monitoring and management can mitigate these problems. The ETOA emerges as a viable surgical option, especially for tumors involving the middle cranial fossa, capable of adapting to individual patient needs and demonstrating efficacy in TS management.

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.

An innovative reconstruction procedure for fractures extending to the posterior orbital floor: utilizing the inferior margin of the greater wing of the sphenoid bone for reconstruction.

PURPOSE: No definitive procedures have been proposed for orbital floor fractures extending to the slope of the posterior end, which is a challenging problem. This study demonstrates the effectiveness of an orbital reconstruction procedure based on anatomical landmarks that we developed, called the three landmarks procedure (TLP). METHODS: This study is a single-center retrospective cohort study conducted by the Department of Otorhinolaryngology, Japanese Red Cross Asahikawa Hospital. Data were collected from April 2000 to December 2023. The effect of TLP and the balloon procedure (BP) on ocular movement was compared. The prevalence of postoperative enophthalmos after TLP was examined. RESULTS: The study included 17 patients who underwent TLP and 25 patients who underwent BP. Postoperative mean Hess area ratio (HAR%) was 98.3 (95% confidence interval (CI), 97.0-99.6) in the TLP group and 88.6 (95% CI 83.2-94.0) in the BP group. Among study patients with fractures extending to the posterior slope, 14 underwent TLP and 16 underwent BP. Postoperative mean HAR% was 98.5 (95% CI 97.3-99.7) in the TLP group and 89.2 (95% CI 82.4-95.8) in the BP group. Among all patients who underwent TLP, mean postoperative enophthalmos was 0.06 mm (95% CI - 0.32 to 0.44). It was 0.14 mm (95% CI - 0.31 to 0.59) among patients with fractures extending to the posterior slope. CONCLUSION: TLP resulted in better postoperative ocular movements than BP. Furthermore, TLP is an effective technique for treating fractures extending to the posterior slope, which are challenging to reconstruct.

Endoscopic trans-orbital approach for the tumor-related epilepsy at the temporal tip.

Minimally invasive surgery is gaining increasing interest in epilepsy surgery. In this video, the authors present the endoscopic transorbital approach for an epileptogenic lesion located at the temporal tip. The patient was a man in his 40s who has had intractable focal impaired awareness seizures and focal to bilateral tonic-clonic seizures since he was 31 years of age. According to the preoperative examination, including stereotactic electroencephalography, a cavernous angioma located at the tip of the right temporal lobe was diagnosed as an epileptogenic lesion. Lesionectomy for this lesion was performed using the endoscopic transorbital approach as minimally invasive surgery and a favorable outcome was achieved. The video can be found here: https://stream.cadmore.media/r10.3171/2024.4.FOCVID2414.

Comparison of endoscopic multiport approaches to the petrous apex: contralateral transmaxillary versus contralateral medial transorbital corridor.

OBJECTIVE: Accessing the petrous apex (PA) via an endoscopic endonasal approach (EEA) is challenging due to its posterior and lateral anatomical relationship with the paraclival carotid artery. Typically, the EEA requires the mobilization or compression of the vessel and the use of angled-lens endoscopes and instruments. A sublabial contralateral transmaxillary (CTM) corridor has been used to overcome these challenges. Still, it requires extensive osteo-meatal disruption and drilling of the medial pterygoid process, which risks the vidian nerve and increases nasal morbidity. Furthermore, the CTM corridor positions the endoscope in the same horizontal plane as the instruments passing through the nostrils, leading to fencing. The authors propose a novel minimally invasive route to the PA, the precaruncular contralateral medial transorbital (cMTO) corridor, to address these issues. This anatomical study compares the EEA+CTM and EEA+cMTO corridors in accessing the PA. METHODS: The authors dissected 14 fresh, preinjected cadaveric specimens (28 sides) using neuronavigation to complete EEA, cMTO, and CTM on each side. In addition to qualitative analysis, they measured and compared the working distance between the entry point (nose, orbit, maxilla) and the petrosal process of the sphenoid bone (PPSB), superomedial PA, and foramen lacerum (FL); angle of attack (AoA); area of surgical freedom; endoscope-instrument fencing angle; and visual angle for each approach. RESULTS: The cMTO corridor provided the shortest working distance to the petroclival region (PA = 67.4 ± 4.47 mm, PPSB = 67.57 ± 4.33 mm, and FL = 66.30 ± 4.77 mm) compared to the CTM (PA = 75.85 ± 3.63 mm, PPSB = 76 ± 3.96 mm, and FL = 74.52 ± 4.26 mm) and to the EEA (PA = 85.16 ± 3.16 mm, PPSB = 84.55 ± 3.02 mm, and FL = 83.42 ± 3.21 mm, p < 0.001). Both CTM and cMTO corridors had a similar visual angle to the PA (20.72° ± 2.16° and 21.63° ± 1.84°, respectively), offering a similar but significantly better visualization than EEA alone (44.71° ± 3.24°, p < 0.001). The cMTO corridor provided better instrument maneuverability than the CTM, as evidenced by a significantly greater fencing angle (30.9° ± 4.9°) than with the CTM (21.7° ± 4.02°, p < 0.001). The vertical AoAs for the EEA, cMTO, and CTM corridors were 9.79° ± 1.75°, 10.65° ± 0.82°, and 9.82° ± 1.43°, respectively (p = 0.009), whereas in the horizontal plane, these were 9.29° ± 1.51°, 9.10° ± 0.73°, and 10.49° ± 1.43° (p < 0.001), respectively. Both the CTM and cMTO corridors offered similar areas of surgical freedom (678.06 ± 99.5 mm2 and 673.59 ± 104.8 mm2, p = 0.986), but they were more significant than that provided by the EEA 487.29 ± 112.9 mm2 (p < 0.001). CONCLUSIONS: The EEA+cMTO multiport technique may be a better alternative than the EEA+CTM multiport approach for targeting the petroclival region. However, clinical validation is required to confirm these laboratory findings.

Spheno-Orbital Meningiomas: The Rationale behind the Decision-Making Process of Treatment Strategy.

Surgery stands as the primary treatment for spheno-orbital meningiomas, following a symptoms-oriented approach. We discussed the decision-making process behind surgical strategies through a review of medical records from 80 patients who underwent surgical resection at the University of Naples Federico II. Different surgical approaches were employed based on the tumor's location relative to the optic nerve's long axis, categorized into lateral (type I), medial (type II), and diffuse (type III). We examined clinical, neuroradiological, surgical, pathological, and outcome factors. Proptosis emerged as the most frequent symptom (97%), followed by visual impairment (59%) and ocular motility issues (35%). Type I represented 20%, type II 43%, and type III 17%. Growth primarily affected the optic canal (74%), superior orbital fissure (65%), anterior clinoid (60%), and orbital apex (59%). The resection outcomes varied, with Simpson grades I and II achieved in all type I cases, 67.5% of type II, and 18% of type III. Recurrence rates were highest in type II (41.8%) and type III (59%). Improvement was notable in proptosis (68%) and visual function (51%, predominantly type I). Surgery for spheno-orbital meningiomas should be tailored to each patient, considering individual characteristics and tumor features to improve quality of life by addressing primary symptoms like proptosis and visual deficits.

The Transorbital Approach: A Comprehensive Review of Targets, Surgical Techniques, and Multiportal Variants.

The transorbital approach (TOA) is gaining popularity in skull base surgery scenarios. This approach represents a valuable surgical corridor to access various compartments and safely address several intracranial pathologies, both intradurally and extradurally, including tumors of the olfactory groove in the anterior cranial fossa (ACF), cavernous sinus in the middle cranial fossa (MCF), and the cerebellopontine angle in the posterior cranial fossa (PCF). The TOA exists in many variants, both from the point of view of invasiveness and from that of the entry point to the orbit, corresponding to the four orbital quadrants: the superior eyelid crease (SLC), the precaruncular (PC), the lateral retrocanthal (LRC), and the preseptal lower eyelid (PS). Moreover, multiportal variants, consisting of the combination of the transorbital approach with others, exist and are relevant to reach peculiar surgical territories. The significance of the TOA in neurosurgery, coupled with the dearth of thorough studies assessing its various applications and adaptations, underscores the necessity for this research. This extensive review delineates the multitude of target lesions reachable through the transorbital route, categorizing them based on surgical complexity. Furthermore, it provides an overview of the different transorbital variations, both standalone and in conjunction with other techniques. By offering a comprehensive understanding, this study aims to enhance awareness and knowledge regarding the current utility of the transorbital approach in neurosurgery. Additionally, it aims to steer future investigations toward deeper exploration, refinement, and exploration of additional perspectives concerning this surgical method.

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.

Anterolateral keyhole transorbital routes to the skull base: a comparative anatomical study.

OBJECTIVE: Although keyhole transorbital approaches are gaining traction, their indications have not been adequately studied comparatively. In this study the authors have defined them also as transwing approaches-meaning that they use the different facies of the sphenoid wing for cranial entry-and sought to compare the four major ones: 1) lateral orbitocraniotomy through a lateral canthal incision (LatOrb); 2) modified orbitozygomatic approach through a palpebral incision (ModOzPalp); 3) modified orbitozygomatic approach through an eyebrow incision (ModOzEyB); and 4) supraorbital craniotomy through an eyebrow incision (SupraOrb), coupled with its expanded version (SupraTransOrb). METHODS: Cadaveric dissections were performed at the neuroanatomy lab. To delineate the skull base exposure, four formalin-fixed heads were used, with two sides dedicated to each approach. The outer limits were assessed via image guidance and were mapped and illustrated accordingly. A fifth head was dissected purely endoscopically, just to facilitate an overview of the transwing concept. Qualitative features were also rigorously examined. RESULTS: The LatOrb proves to be more versatile in the middle cranial fossa (MCF), whereas the anterior cranial fossa (ACF) exposure is limited to a small area above the sphenoid ridge. An anterior clinoidectomy is possible; however, the exposure of the roof of the optic canal is suboptimal. The ModOzPalp adequately exposes both the ACF and MCF. Its lateral trajectory allows the inferior to superior view, yet there is restricted access to the medial anterior skull base (olfactory groove). The ModOzEyB also provides extensive exposure of the ACF and MCF, but has a more superior to inferior trajectory compared to the ModOzPalp, making it more appropriate for pathology reaching the medial anterior skull base or even the contralateral side. The anterior clinoidectomy is performed with improved visualization of the optic canal. The SupraOrb provides mainly anterior cranial base exposure, with minimal middle fossa. An anterior clinoidectomy can be performed, but without any direct observation of the superior orbital fissure. Some MCF access can be accomplished if the lateral sphenoid wing is drilled inferiorly, leading to its highly versatile variant, the SupraTransOrb. CONCLUSIONS: All the aforementioned approaches use the sphenoid wing as skull base corridor from a specific orientation point; hence these are designated as transwing approaches. Their peculiarities mandate careful case selection for the effective and safe completion of the surgical goals.

Endoscopic transorbital approach in children: surgical technique and early results.

OBJECTIVE: In this study, the authors aimed to describe the endoscopic transorbital approach (ETOA) in children. METHODS: Six pediatric patients (2 girls and 4 boys) underwent the ETOA for paramedian skull base lesions at a single institution between September 2016 and February 2023. RESULTS: The median age at the time of surgery was 7.5 (range 4-18) years. The median follow-up period was 33 (range 9-60) months. In this series, the ETOA level of difficulty included stage 1 (n = 2, 33.3%), stage 3 (n = 3, 50%), and stage 5 (n = 1, 16.7%). The ETOA was performed for tumor resection in 4 cases; the final pathology consisted of fibrous dysplasia, pilocytic astrocytoma, metastatic neuroblastoma, and choroid plexus papilloma. The procedure was also performed for repair of a petrous apex meningocele and for lateral orbital wall decompression of traumatic lateral rectus muscle entrapment. One patient experienced a transient cranial nerve III palsy after the procedure. There were no operative deaths in this series. CONCLUSIONS: In select cases, the ETOA can be considered a minimally invasive alternative for conventional skull base approaches in the armamentarium of pediatric skull base surgery. Further investigation and the accumulation of experience are warranted in the future to enhance the efficacy and applicability of the ETOA in pediatric patients.

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

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

Endoscopic transorbital approach bone pillars: a comprehensive stepwise anatomical appraisal.

OBJECTIVE: The endoscopic superior eyelid transorbital approach has garnered significant consideration and gained popularity in recent years. Detailed anatomical knowledge along with clinical experience has allowed refinement of the technique as well as expansion of its indications. Using bone as a consistent reference, the authors identified five main bone pillars that offer access to the different intracranial targeted areas for different pathologies of the skull base, with the aim of enhancing the understanding of the intracranial areas accessible through this corridor. METHODS: The authors present a bone-oriented review of the anatomy of the transorbital approach in which they conducted a 3D analysis using Brainlab software and performed dry skull and subsequent cadaveric dissections. RESULTS: Five bone pillars of the transorbital approach were identified: the lesser sphenoid wing, the sagittal crest (medial aspect of the greater sphenoid wing), the anterior clinoid, the middle cranial fossa, and the petrous apex. The associations of these bone targets with their respective intracranial areas are reported in detail. CONCLUSIONS: Identification of consistent bone references after the skin incision has been made and the working space is determined allows a comprehensive understanding of the anatomy of the approach in order to safely and effectively perform transorbital endoscopic surgery in the skull base.

Endoscopic precaruncular medial transorbital and endonasal multiport approaches to the contralateral skull base: a clinicoanatomical study.

OBJECTIVE: Minimally invasive endoscopic endonasal multiport approaches create additional visualization angles to treat skull base pathologies. The sublabial contralateral transmaxillary (CTM) approach and superior eyelid lateral transorbital approach, frequently used nowadays, have been referred to as the "third port" when used alongside the endoscopic endonasal approach (EEA). The endoscopic precaruncular contralateral medial transorbital (cMTO) corridor, on the other hand, is an underrecognized but unique port that has been used to repair CSF rhinorrhea originating from the lateral sphenoid sinus recess. However, no anatomical feasibility studies or clinical experience exists to assess its benefits and demonstrate its potential role in multiport endoscopic access to the other contralateral skull base areas. In this study, the authors explored the application and potential utility of multiport EEA combined with the endoscopic cMTO approach (EEA/cMTO) to three target areas of the contralateral skull base: lateral recess of sphenoid sinus (LRSS), petrous apex (PA) and petroclival region, and retrocarotid clinoidocavernous space (CCS). METHODS: Ten cadaveric specimens (20 sides) were dissected bilaterally under stereotactic navigation guidance to access contralateral LRSS via EEA/cMTO. The PA and petroclival region and retrocarotid CCS were exposed via EEA alone, EEA/cMTO, and EEA combined with the sublabial CTM approach (EEA/CTM). Qualitative and quantitative assessments, including working distance and visualization angle to the PA, were recorded. Clinical application of EEA/cMTO is demonstrated in a lateral sphenoid sinus CSF leak repair. RESULTS: During the qualitative assessment, multiport EEA/cMTO provides superior visualization from a high vantage point and better instrument maneuverability than multiport EEA/CTM for the PA and retrocarotid CCS, while maintaining a similar lateral trajectory. The cMTO approach has significantly shorter working distances to all three target areas compared with the CTM approach and EEA. The mean distances to the LRSS, PA, and retrocarotid CCS were 50.69 ± 4.28 mm (p < 0.05), 67.11 ± 5.05 mm (p < 0.001), and 50.32 ± 3.6 mm (p < 0.001), respectively. The mean visualization angles to the PA obtained by multiport EEA/cMTO and EEA/CTM were 28.4° ± 3.27° and 24.42° ± 5.02° (p < 0.005), respectively. CONCLUSIONS: Multiport EEA/cMTO to the contralateral LRSS offers the advantage of preserving the pterygopalatine fossa contents and the vidian nerve, which are frequently sacrificed during a transpterygoid approach. This approach also offers superior visualization and better instrument maneuverability compared with EEA/CTM for targeting the petroclival region and retrocarotid CCS.

Pediatric Orbital and Skull Base Pathology.

Pediatric orbital and skull base pathologies encompass a spectrum of inflammatory, sporadic, syndromic, and neoplastic processes that require a broad and complex clinical approach for both medical and surgical treatment. Given their complexity and often multicompartment involvement, a multidisciplinary approach for diagnosis, patient and family counseling, and ultimately treatment provides the best patient satisfaction and clinical outcomes. Advances in minimally invasive surgical approaches, including endoscopic endonasal and transorbital approaches allows for more targeted surgical approaches through smaller corridors beyond more classic transcranial or transracial approaches.