Surgical anatomy of the cavernous sinus, superior orbital fissure, and orbital apex via a lateral orbitotomy approach: a cadaveric anatomical study

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.

Multiport combined endoscopic endonasal and transorbital approach to orbital schwannoma

Background

We present a case report describing the use of combined endoscopic endonasal and transorbital approach (EETOA) for intraorbital schwannoma that grew rapidly during pregnancy.

Case Description

A 27-year-old woman who presented with headache was incidentally diagnosed with a tumor mass 1 cm in diameter near the right superior orbital fissure. Treatment of the tumor was deferred to follow-up. One month later, the patient became pregnant, and in the last trimester, she developed right abducens palsy and mildly dilated pupil. Magnetic resonance imaging (MRI) showed that the tumor mass had grown rapidly with a maximal diameter of 5 cm and had extended into the orbit through the superior orbital fissure. After spontaneous vaginal delivery, EETOA was planned to remove both the intraorbital region and cavernous sinus compartment to avoid craniotomy. Surgical resection began with an endoscopic endonasal approach. Orbital decompression was performed by removing the lamina papyracea, and the tumor was resected in the lateral cavernous sinus compartment. An eyebrow incision was made, and endoscopic transorbital surgery was performed to remove the intraorbital region. Multi-perspective views during EETOA enabled gross total resection of the tumor and confirmed by intraoperative MRI. The pathological diagnosis was schwannoma. The patient's abducens nerve palsy improved after surgery.

Conclusion

EETOA can offer maximal exposure and resection for tumors extending from the cavernous sinus to the orbit without craniotomy in selected cases.

Resection of Meningiomas Invading the Cavernous Sinus: Treatment Strategy and Clinical Outcomes

Background/Objectives: Resection of tumors invading the cavernous sinus (CS) carries a risk of injury to the cranial nerves and internal carotid artery. Therefore, radical surgery involving lesions around the CS remains challenging, especially for lesions invading the CS, optic sheath, and oculomotor cave. Here, we describe a surgical strategy for meningiomas invading these structures and report on the clinical outcomes. Methods: Surgical resection was indicated in patients with neurological symptoms or rapid tumor growth for the restoration of cranial nerve function. We investigated 13 patients who had preoperative images of CS invasion, underwent surgical resection, and were followed-up with magnetic resonance imaging for at least 1 year between July 2017 and July 2024. Their preoperative symptoms, postoperative course, adjuvant therapy, postoperative complications, degree of resection, and recurrence were evaluated. Results: The mean patient age was 59.1 years (range, 23-73 years), and 10 were female. Major preoperative symptoms included oculomotor nerve paresis in 8 patients (61.5%), abducens nerve paresis in 6 (46.2%), visual disturbance in 7 (53.8%), and brain swelling in 3 (23.1%). These symptoms improved at least partially after surgery in 7 (87.5%), 5 (83.3%), 7 (100%), and 3 (100%) patients, respectively. Major postoperative complications included contralateral visual deterioration in 1 patient (7.7%) and brief transient slight hemiparesis caused by internal carotid vasospasm or dissection in 2 (15.4%). Four patients with residual atypical meningioma in the CS underwent intensity-modulated radiotherapy (IMRT). The lesions in 6 patients recurred or regrew, resulting in additional treatment with stereotactic radiosurgery in 2 patients, IMRT in 3, and resection in 1. Conclusions: Our surgical strategy for the surgical resection of meningiomas in and around the CS for the restoration of cranial nerve function is safe and effective, with only transient acceptable injuries. Even if the tumor in the CS is too stiff to be removed, it is important to open the optic nerve sheath and oculomotor cave widely to effectively remove the tumor.

Management of the skull base invasion in spheno-orbital meningiomas

BACKGROUND

The tumor invasion of the skull base structures is very frequent in spheno-orbital meningiomas. The aim of the present study is to evaluate the invasion rate of skull base structures and the best surgical approach and management.

METHODS

The surgical series of 80 spheno-orbital meningiomas was reviewed. The tumors were classified according to the intraorbital location with respect to the optic nerve axes into three types: I-lateral: II-medial; III-diffuse. The invasion of the orbital apex, optic canal, superior orbital fissure, anterior clinoid, ethmoid-sphenoid sinuses, and infratemporal fossa was evaluated. The rate and extension of involvement of these structures was correlated with the intraorbital location and the surgical approach. The preoperative ophtalmological symptoms and signs and their outcome were also evaluated.

RESULTS

Proptosis was found in 79 patients (97%), variable decrease of the visual function in 47 patients (59%), and deficits of the eye movements in 28(35%). The invasion of the optic canal (74%), superior orbital fissure (65%), anterior clinoid (60%), and orbital apex (59%) was more frequently found, whereas the tumor extension into the ethmoid-sphenoid sinuses (4%) and infratemporal fossa (4%) was rare. Types II and III meningiomas showed significantly higher involvement of the skull base structures than type I ones, which only had 15% invasion of the optic canal. Remission or significant improvement of the visual function occurred postoperatively in 24 among 47 cases (51%), with a higher rate for type I meningiomas vs. other types (p = 0.021, p = 0.019) and worsening in 7 (15%).

CONCLUSIONS

Spheno-orbital meningiomas growing in the lateral orbital compartment show no involvement of the skull base structures excepting the optic canal as compared to those growing medially or diffusely. The surgical resection of tumor invading the skull base structures should be more extensive as possible, but the risk of optic and oculomotor deficits must be avoided.

Morphometric evaluation of the anatomical relationships between the superior orbital fissure and the orbital structures based on computed tomography images with clinical implications

PURPOSE

To assist in surgical planning in endoscopic approaches, we analyzed the morphometric measurements of the superior orbital fissure (SOF) and optic canal (OC) by three-dimensional multislice computed tomography (3D MDCT) and evaluated them according to age, gender, and lateralization.

METHODS

The study analyzed 219 MDCT images (114 women, 105 men) from individuals aged 18-90. Measurements of SOF and OC were performed on 3D MDCT images in the axial plane and with 3D-Slicer software.

RESULTS

The distance between the infraorbital foramen and the anterior entrance of the maxillary sinus (CBW) (p < 0.001), the distance between the CBW and the lateral point of the SOF (p = 0.001), and the Angle 1 (p = 0.028) were higher in women than in men. While the SOF length and on 3D the SOF width were higher in women than men (p < 0.001 and (p = 0.001, respectively), the lateral wall length OC was higher in men than women (p = 0.045). According to SOF classification, SOF length was highest in type II and lowest in type VIII (p = 0.025), SOF width was highest in type I and lowest in type VI (p < 0.001). No significant difference was found based on age groups and lateralization in all parameters.

CONCLUSION

We found that as the SOF width increased, the SOF length also increased, and there was a statistically strong positive correlation. These findings can contribute to a more effective and safe operation by improving and updating surgeons' knowledge about safe distances to SOF in endoscopic procedures from a 3D MDCT perspective.

Exposure of the Cavernous Sinus via the Endoscopic Transorbital and Endoscopic Endonasal Approaches: A Comparative Study

OBJECTIVE

To compare the endoscopic transorbital approach (ETOA) and endoscopic endonasal approach (EEA) in terms of cavernous sinus (CS) exposure.

METHODS

Four cadaveric heads (8 sides) were dissected. The CS was accessed using the EEA and ETOA. Stereotactic measurements of the length of the main structures exposed, angles of attack, depths of surgical corridor, and areas of exposure were obtained and compared between the approaches. An illustrative case is also presented.

RESULTS

The endoscopic transorbital approach (ETOA) exposed the lateral and superior compartments of the CS without obstruction by the internal carotid artery (ICA). The EEA exposed all compartments after mobilizing the ICA. Both approaches enabled similar exposure of the cranial nerves. The depth of surgical corridor was significantly shorter with the ETOA (P < 0.01). The areas of lateral compartment exposure were similar. As the number of instruments placed into the surgical channel increased, the available angles of attack with the ETOA became smaller and were smaller than those of the EEA. In the clinical case presented, the tumor was successfully removed without complications.

CONCLUSIONS

The ETOA has the advantages of a sterile surgical channel, short operation time, little patient trauma, short surgical corridor, large exposure area, and interdural pathway; moreover, it allows dissection through the interdural space without entering the neurovascular compartment of the CS. Although the space for manipulation of instruments is limited, the ETOA is suitable for treating selected tumors in the superior and lateral compartments of the CS.

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 rule of five: A novel anatomical landmark for approaching cavernous sinus content

BACKGROUND

The main objective of this study is to enhance neurosurgeons' anatomical knowledge by providing specific anatomical references of the cavernous sinus (CS). However, it is essential to clarify that our study does not seek to establish an absolute intraoperative rule due to the inherent anatomical variability that must be considered.

METHODS

Fifty-three cadaveric specimens were procured from the Forensic Institute (Bogotá) and subjected to dissection through an extradural approach. The measurements were taken in two distinct phases. The first phase involved the measurement of various anatomical structures in 25 specimens with respect to the anterior and posterior clinoids. The second phase, which was conducted 5 years later, involved the measurement of the distance between the foramen rotundum and the foramen ovale in 28 specimens using the L&W tools microcaliper.

RESULTS

In 25 specimens, a perpendicular imaginary line was drawn from the lateral tip of the anterior clinoid to the floor of the medial fossa. This facilitated access to the Parkinson's triangle, which is located between the IV cranial nerve and the ophthalmic V1 nerve, revealing a constant distance of 5 mm between the lateral tip of the anterior clinoid and the IV cranial nerve. Furthermore, in 28 specimens, the mean distance from the foramen rotundum to the foramen ovale was found to be 1.3 cm bilaterally.

CONCLUSION

The rule of five is a valuable tool for comprehensively understanding the anatomy of the CS, providing a reference point for the different normal anatomical structures within the CS.

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.

Late orbital metastasis from colon cancer complicated by multiple tumors in the breast, lung, liver, and spine

A 69-year-old woman sustained progressive proptosis for 2 months. The patient had undergone surgery for resection of colon cancer 10 years prior, which was considered to have been completely cured 5 years prior. She was also aware of a hard mass in her left breast, but it had been left untreated. Furthermore, she experienced back pain for a month. Blood examination revealed an elevated level of serum carcinoembryonic antigen, at 17.4 ng/mL (< 5). Computed tomography (CT) revealed a tumor occupying the superolateral part of the right orbit, with intratumoral calcifications and destructive changes in the lateral orbital wall. On magnetic resonance imaging, it appeared as a heterogeneously enhancing, extraconal tumor, 44 mm × 31 mm in maximal dimension, extending into the middle fossa and the adjacent subcutaneous region. Fluorodeoxyglucose positron emission tomography/CT revealed abnormal accumulation in the left breast, T12 vertebra, liver, and lung, in addition to the orbital tumor. The patient underwent total tumor resection through a lateral orbitotomy. Histological examination of the tumor was highly suggestive of a metastatic colon cancer. Late metastasis should be assumed as a differential diagnosis that can be determined only through histological verification.

A systematic review of the surgical anatomy of the orbital apex

PURPOSE

The orbital apex is the narrowest part of the orbit, housing the link between the intracranial cavity and orbit. Knowledge of orbital apex anatomy is crucial to selecting a surgical approach and reducing the risk of complications. Our purpose is to summarize current knowledge on surgical anatomy and attempt to reach a consensus on definition of the orbital apex.

METHODS

The online databases of Embase, the Cochrane library, Web of Science and PubMed (MEDLINE) were queried in a comprehensive bibliographic search on the (surgical) anatomy of the orbital apex and consisted of a combination of two subjects, using indexed terms and free text: "Orbital Apex" and "Orbital Anatomy."

RESULTS

A total of 114 relevant papers were included in this review. Numerous anatomical variations are described in the literature. Variations of the optic canal include duplication (0.64%) and keyhole anomaly (2.65%). Variations in pneumatization of the anterior clinoid process were unilateral in almost 10%, bilateral in 9%, and normal in 72%. A rare variant of the superior orbital fissure (SOF) is Warwick's foramen, which appears as if the lowest portion of the SOF was separated from the main fissure by a transverse bony bridge.

CONCLUSION

The definition of the orbital apex varies in the literature, and further research would most likely identify additional variations. A universal definition reporting these variations and pathology and imaging findings is essential for determining the optimal surgical approach to the orbital apex.

Lateral transorbital approach: an alternative microsurgical route for supratentorial cerebral aneurysms

OBJECTIVE

Transorbital approaches for neurosurgery have recently attracted attention and several anatomical studies have aimed to improve these techniques, but significant deficiencies in clinical practice remain, especially for aneurysm surgery. The authors present an alternative microsurgical route and the results of an analysis of patients with intracranial aneurysms who underwent a lateral transorbital approach (LTOA) using lateral orbito-zygoma-sphenotomy (LOZYGS).

METHODS

The clinical and surgical results of a series of 54 consecutive patients with 1 or more aneurysms who underwent surgery via LTOA are reported. A lateral orbitotomy was performed after making a 3-cm skin incision parallel to the lateral orbital rim. A second bone flap, which included the zygoma and sphenoid bones that form the lateral orbital wall, was removed. The lesser sphenoid wing, including the anterior clinoid process, was fully drilled, except in cases of middle cerebral artery (MCA) aneurysms. Cisternal dissection was performed using the classic microsurgical technique starting from the proximal Sylvian fissure and carotid cistern. After the aneurysm was clipped following microsurgical principles, the dura mater was closed in a watertight fashion and 2-piece bone reconstruction was achieved.

RESULTS

Sixty aneurysms in 54 patients were clipped using the LOZYGS route. Twenty-one aneurysms were located on the MCA, 30 on the anterior communicating artery, 8 on the internal carotid artery, and 1 at the apex of the basilar artery. The unruptured-to-ruptured aneurysm ratio was 17:43. The operative field was moved to the orbit using the LTOA to avoid interference by bone and muscle tissues. Early proximal control was achieved using a short working distance and direct exposure of the base of the cerebrum, without any requirement for retraction. Because different view angles and surgical corridors were used, no segment of the aneurysm or the parent artery remained unexposed. Therefore, the introduction of additional tools was not required.

CONCLUSIONS

The LTOA allowed enhanced broad-perspective exposure of the operative field, early proximal control, and satisfactory surgical freedom. This alternative surgical approach safely exposed the target area and the operative field. The LOZYGS route is safe and effective for the LTOA and microsurgical clipping of anterior circulation aneurysms. According to the authors' surgical experience and clinical experience, the LTOA can be considered an alternative surgical route to supratentorial aneurysm surgery.

Expanded exposure and detailed anatomic analysis of the superior orbital fissure: Implications for endonasal and transorbital approaches

This study aimed to ascertain the maximal exposure of the superior orbital fissure (SOF) afforded by combining endonasal and transorbital endoscopic approaches. Six cadaveric specimens (12 sides) were dissected using endonasal and transorbital endoscopic approaches to access the SOF. The order of the approaches was alternated in each specimen (eg, starting with an endonasal approach in one side followed by a transorbital exposure and reversing the order on the contralateral side). Maximal exposure of the SOF and its contents for individual and combined approaches were explored. The endonasal corridor provided adequate access to the inferomedial 1/3 of the SOF and including the proximal segments of cranial nerves (CN) III, V₁ and VI. A transorbital approach was superior accessing the superolateral 2/3's of the SOF, including the superior ophthalmic vein, lacrimal nerve, and distal segment of the CN VI at the lateral aspect; the nasociliary nerve and divisions of CN III centrally; and the frontal nerve and CN IV at the dorsal aspect of levator palpebrae superioris. This study suggests that a combined endonasal and transorbital exposure of the SOF may be advantageous to address lesions in this challenging region.

Vena capitis prima and the cavernous sinus in human embryos and fetuses

After the intracranial venous-drainage route is switched from the vena capitis prima (VCP) to the transverse sinus, the cavernous sinus is considered to develop from a connecting part of the VCP with the ophthalmic vein (OPV). Observations of histological sections from 12 embryos and 47 fetuses (6-35 weeks) demonstrated that (1) at six weeks, a major tributary of the VCP ran inferiorly in the plica ventralis at the mesencephalic flexure (future tentrium cerebelli) and merged with the OPV in the medial side of the trigeminal ganglion; (2) at seven weeks, being independent of the laterally located primary veins, the superior petrosal sinus (SPS) developed medially in the plica, ran superiorly, and appeared to make an initial confluence with the transverse sinus; (3) until 15-16 weeks, parasellar veins were limited to a few branches of the OPV without communication with the SPS on the lateral surface of the trigeminal ganglion; (4) after 15-16 weeks, parasellar veins increased in number and volume but did not yet drain into the SPS but rather into the newly built inferior petrosal sinus; and (5) near term, parasellar veins started venous drainage to the SPS, whereas few veins were evident around the intracavernous abducens nerve. Consequently, the inferior petrosal sinus might originate from a remnant of the VCP (the so-called pro-otic sinus), but after midterm, most parasellar veins appeared to develop from the OPV without any contribution of the SPS. These findings suggest that parasellar sinus-network might be established after birth.

Pure Endoscopic Lateral Orbitotomy Approach to the Cavernous Sinus, Posterior, and Infratemporal Fossae: Anatomic Study

Objective  The aim of this anatomic study is to describe a fully endoscopic lateral orbitotomy extradural approach to the cavernous sinus, posterior, and infratemporal fossae. Material and Methods  Three prefixed latex-injected head specimens (six orbital exposures) were used in the study. Before and after dissection, a computed tomography scan was performed on each cadaver head and a neuronavigation system was used to guide the approach. The extent of bone removal and the area of exposure of the targeted corridor were evaluated with the aid of OsiriX software (Pixmeo, Bernex, Switzerland). Results  The lateral orbital approach offers four main endoscopic extradural routes: the anteromedial, posteromedial, posterior, and inferior. The anteromedial route allows a direct route to the optic canal by removal of the anterior clinoid process, whereas the posteromedial route allows for exposure of the lateral wall of the cavernous sinus. The posterior route is targeted to Meckel's cave and provides access to the posterior cranial fossa by exposure and drilling of the petrous apex, whereas the inferior route gives access to the pterygopalatine and infratemporal fossae by drilling the floor of the middle cranial fossa and the bone between the second and third branches of the trigeminal nerve. Conclusion  The lateral orbitotomy endoscopic approach provides direct access to the cavernous sinus, posterior, and infratemporal fossae. Advantages of the approach include a favorable angle of attack, minimal brain retraction, and the possibility of dissection within the two dural layers of the cavernous sinus without entering its neurovascular compartment.

Surgical Management of Pilocytic Astrocytoma of the Optic Nerve: A Case Report and Review of the Literature

Optic nerve astrocytomas (ONAs) are frequent types of optic nerve gliomas (ONGs), which can affect the visual pathway. An 18-year-old male patient was admitted to our department with right-sided intraorbital/retrobulbar swelling, which progressively grew over several months. Clinical examination showed right-sided diplopia, mydriasis, low visual acuity (0.4), exophthalmus (3 cm), epiphora, and severe retrobulbar pain. There was a family history of high-grade (IV) astrocytomas in which two of the family members died due to the disease. Preoperative MRI scan revealed a soft tissue mass around the retrobulbar area of the right eye with intact orbital bony walls. Surgery was performed whereby it was dissected freely from the muscles and was separated from the optic nerve and the globe. Histopathologic analysis confirmed a benign astrocytoma. The follow-up examination revealed no recurrent or residual tumor. A systemic review of the literature indicates that early diagnosis and experienced multidisciplinary management are required in case of unilateral, resectable forms of ONAs with no distant metastasis, in order to provide a long-time survival of patients. Surgical intervention of unilateral ONAs is a relatively safe procedure, allowing complete or partial tumor removal with minimal morbidity and low recurrence rate.