Objective: The endoscopic transorbital approach (ETOA) and transorbital anterior clinoidectomy have been suggested as novel procedures through which to reach the superolateral compartments of the orbit, allowing optic canal decompression. However, there is limited literature describing the technical details and surgical outcomes of these procedures. In this study, the authors aimed to analyze the feasibility and efficacy of endoscopic transorbital decompression of the optic canal through anterior clinoidectomy for compressive optic neuropathic lesions.

Methods: Between 2016 and 2022, the authors performed ETOA for compressive optic neuropathic lesions in 14 patients. All these patients underwent transorbital anterior clinoidectomy through the surgically defined "intraorbital clinoidal triangle," which is composed of the roof of the superior orbital fissure, the medial margin of the optic canal, the medial border of the superior orbital fissure, and the optic strut. Demographic data, tumor characteristics, pre- and postoperative imaging, pre- and postoperative visual examinations, and surgical outcomes were retrospectively reviewed.

Results: The mean age at the time of ETOA was 53.3 years (range 41-64 years), and the mean follow-up was 16.8 months (range 6.7-51.4 months). The inclusion criterion in this study was having a meningioma (14 patients). In the preoperative visual function examination, 7 patients with a meningioma showed progressive visual impairment. After endoscopic transorbital optic canal decompression, visual function improved in 5 patients, remained unchanged in 8 patients, and worsened in 1 patient. No new-onset neurological deficit was associated with ETOA and anterior clinoidectomy in any patients.

Conclusions: Endoscopic transorbital decompression of the optic canal with extradural anterior clinoidectomy is a safe and feasible technique that avoids significant injury to the clinoidal internal carotid artery and surrounding neurovascular structures.

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.

Objective: The endoscopic transorbital approach (ETOA) is a minimally invasive approach that could be particularly appropriate for management of spheno-orbital meningiomas. The aim of this study was to perform a systematic review of the literature on the management of spheno-orbital meningiomas via the minimally invasive ETOA, searching for clinical scenarios in which this approach could be best indicated. A secondary aim was to describe 4 illustrative cases.

Methods: A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data including patient demographics, tumor features, and surgical and postoperative outcomes were collected. Cases from our initial experience with ETOA were included in the data.

Results: Data of 58 patients from 9 selected records and from our surgical series were collected. Subtotal, near-total, and gross total resection rates were 44.8%, 10.3%, and 32.7%, respectively. Symptom improvement after surgery was 100% for proptosis, 93% for visual impairment, and 87% for ophthalmoplegia. The most common postoperative complications were transient ophthalmoplegia and maxillary nerve hypoesthesia. Cerebrospinal fluid leak was reported in 2 patients.

Conclusions: Our findings support the use of the ETOA for management of spheno-orbital meningiomas, particularly in at least 3 clinical scenarios: 1) when predominant hyperostotic bone is present; 2) when a globular tumor not showing excessive medial or inferior infiltration is being treated; 3) as part of a multistage treatment for diffuse lesions.

Objective: Starting from an anatomic study describing the possibility of reaching the temporal region through an endoscopic transorbital approach, many clinical reports have now demonstrated the applicability of this strategy when dealing with intra-axial lesions. The study aimed to provide both a qualitative anatomic description of the temporal region, as seen through a transorbital perspective, and a quantitative analysis of the amount of temporal lobe resection achievable via this route.

Material and methods: A total of four cadaveric heads (eight sides) were dissected at the Laboratory of Surgical Neuroanatomy (LSNA) of the University of Barcelona, Spain. A stepwise description of the resection of the temporal lobe through a transorbital perspective is provided. Qualitative anatomical descriptions and quantitative analysis of the amount of the resection were evaluated by means of pre- and post-dissection CT and MRI scans, and three-dimensional reconstructions were made by means of BrainLab^®Software.

Results: The transorbital route gives easy access to the temporal region, without the need for extensive bone removal. The resection of the temporal lobe proceeded in a subpial fashion, mimicking what happens in a surgical scenario. According to our quantitative analysis, the mean volume removed was 51.26%, with the most superior and lateral portion of the temporal lobe being the most difficult to reach.

Conclusion: This anatomic study provides qualitative and quantitative details about the resection of the temporal lobe via an endoscopic transorbital approach. Our results showed that the resection of more than half of the temporal lobe is possible through this surgical corridor. While the anterior, inferior, and mesial portions of the temporal lobe were easily accessible, the most superior and lateral segment was more difficult to reach and resect. Our study serves as an integration to the current anatomic knowledge and clinical practice knowledge highlighting and also as a starting point for further anatomic studies addressing more selected segments of the temporal lobe, i.e., the mesial temporal region.

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.

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.