Modified Lateral Orbitotomy Approach to Lesions of the Orbital Apex, Superior Orbital Fissure, Cavernous Sinus, and Middle Cranial Fossa

Microanatomy of the Temporal Division of the Facial Nerve in the Periorbital Region Applied to Minimally Invasive Keyhole Approaches

BACKGROUND

Minimally invasive keyhole approaches to the anterior skull base and circle of Willis require small incisions near distal branches of the temporal division (TD) of the facial nerve. Few studies have focused on planning the incision to avoid the TD branches and maximize exposure in these approaches. This study aimed to define a safe zone away from the TD branches for skin incision during minimally invasive keyhole approaches using reliable and practical skin landmarks.

METHODS

In 5 cadaveric heads (10 sides), a Cartesian system was established with the orbitomeatal line connecting the lateral canthus and the external acoustic meatus (x-axis). A perpendicular line was drawn to the x-axis at the lateral canthus (y-axis). TD branches were dissected proximally to distally until the nerve-muscle junction of the orbicularis oculi and fronto-occipitalis muscles. Nerve-muscle junction points were registered in the Cartesian system. Probabilistic heat maps were generated to define a periorbital safe zone.

RESULTS

A median of 3 branches each innervated the orbicularis oculi and fronto-occipitalis. A semicircular area centered on the lateral canthus with a radius of 10 mm was found to have low (<10%) chance of containing a TD branch. This safe zone could be extended posteriorly to 15 mm inferior to the orbitomeatal line.

CONCLUSIONS

Identifying a safe zone for preserving TD branches is crucial for surgical incisions planned in the superolateral region of the orbit. This study provides a clinically applicable and reproducible landmark for planning incisions commonly used during minimally invasive keyhole approaches.

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.

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

BACKGROUND AND OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Inferior orbital fissure release to access the inferolateral orbital apex

OBJECTIVE

To describe release of the inferior orbital fissure (IOF) as a novel surgical technique that will improve access to the inferior and inferolateral orbital apex.

DESIGN

Laboratory investigation.

PARTICIPANTS

Human cadaver heads.

METHODS

Cadaveric dissection study whereby the technique of an IOF release was performed. A swinging eyelid preseptal approach was used to enable a subperiosteal dissection to the orbital floor without obstruction from orbital fat prolapse. A plane was dissected between periorbita and Muller's muscle, the smooth muscle that overlies the entire length of the IOF. Measurements were taken in the sagittal plane from a point on the inferior orbital rim directly above the infraorbital foramen to the most posterior aspect of the orbital floor.

RESULTS

Fifteen orbits from 8 cadaver heads were dissected with the aid of a rigid 0-degree endoscope and microsurgical instruments. This study demonstrated that an additional 10.93 ± 2.10 mm of access to the orbital apex was gained after the release of periorbita from the IOF.

CONCLUSION

We propose that the IOF release can be adopted as an adjunctive technique to orbital surgery of the inferior and inferolateral orbital apex.

Biomechanical analysis of fixation methods for bone flap repositioning after lateral orbitotomy approach: A finite element analysis

OBJECTIVE

In ophthalmic surgery, different materials and fixation methods are employed for bone flap repositioning after lateral orbitotomy approach (LOA), yet there is no unified standard. This study aims to investigate the impact of different fixation strategies on orbital stability through Finite Element Analysis (FEA) simulations of the biomechanical environment for orbital rim fixation in LOA.

METHODS

A Finite Element Model (FEM) was established and validated to simulate the mechanical responses under various loads in conventional lateral orbitotomy approach (CLOA) and deep lateral orbital decompression (DLOD) using single titanium plate, double titanium plates, and double absorbable plates fixation methods. The simulations were then validated against clinical cases.

RESULTS

Under similar conditions, the maximum equivalent stress (MES) on titanium alloy fixations was greater than that on absorbable plate materials. Both under static and physiological conditions, all FEM groups ensured structural stability of the system, with material stresses remaining within safe ranges. Compared to CLOA, DLOD, which involves the removal of the lateral orbital wall, altered stress conduction, resulting in an increase of MES and maximum total deformation (MTD) by 1.96 and 2.62 times, respectively. Under a horizontal load of 50 N, the MES in FEM/DLOD exceeded the material's own strength, with an increase in MES and MTD by 3.18 and 6.64 times, respectively, compared to FEM/CLOA. Under a vertical force of 50 N, the MES sustained by each FEM was within safe limits. Bone flap rotation angles remained minimally varied across scenarios. During follow-up, the 12 patients validated in this study did not experience complications related to the internal fixation devices.

CONCLUSION

Under static or physiological conditions, various fixation methods can effectively maintain stability at the orbitotomy site, and absorbable materials, with their smoother stress transmission properties, are more suited for application in CLOA. Among titanium plate fixations, single titanium plates can better withstand vertical stress, while double titanium plates are more capable of handling horizontal stress. Given the change in the orbital mechanical behavior due to DLOD, enhanced fixation strength should be considered for bone flap repositioning.

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.

[Interdisciplinary Management of Orbital Diseases]

Diagnosis and therapy of orbital diseases is an interdisciplinary challenge, in which i.e. otorhinolaryngologists, ophthalmologists, radiologists, radiation therapists, maxillo-facial surgeons, endocrinologists, and pediatricians are involved. This review article describes frequent diseases which both, otolaryngologists and ophthalmologists are concerned with in interdisciplinary settings. In particular the inflammatory diseases of the orbit including orbital complications, autoimmunological diseases of the orbit including Grave´s orbitopathy, and primary and secondary tumors of the orbit are discussed. Beside describing the clinical characteristics and diagnostic steps the article focusses on the interdisciplinary therapy. The review is completed by the presentation of most important surgical approaches to the orbit, their indications and possible complications. The authors tried to highlight the relevant facts despite the shortness of the text.

The Endoscopic Lateral Transorbital Approach for the Removal of Select Sphenoid Wing and Middle Fossa Meningiomas. Surgical Technique and Short-Term Outcomes

BACKGROUND AND OBJECTIVE

The endoscopic lateral transorbital approach (eLTOA) is a relatively new approach to the skull base that has only recently been applied in vivo in the management of complex skull base pathology. Most meningiomas removed with this approach have been in the spheno-orbital location. We present a series of select purely sphenoid wing and middle fossa meningiomas removed through eLTOA. The objective here was to describe the selection criteria and results of eLTOA for a subset of sphenoid wing and middle fossa meningiomas.

METHODS

This is a retrospective study based on a prospectively maintained database of consecutive cases of eLTOA operated on at our institution by the lead author. The cohort's clinical and radiographic characteristics and outcome are presented.

RESULTS

Five patients underwent eLTOA to remove 3 sphenoid wing and 2 middle fossa meningiomas. The mean tumor volume was 11.9 cm 3 . Gross total resection was achieved in all cases. There were no intraoperative complications. Postoperatively, there was one case of subretinal hemorrhage, which was corrected by open vitrectomy repair, and one case of cerebrospinal fluid leak, which resolved with lumbar drainage. Three patients presented with visual impairment, 1 improved, 1 remained stable, and 1 worsened, but returned to stable after vitrectomy repair. All patients have been free of disease at a median follow-up of 8.9 months.

CONCLUSION

eLTOA provides a direct minimal access corridor to certain well-selected sphenoid wing and middle fossa meningiomas. eLTOA minimizes brain retraction and provides a high rate of gross total resection. Meningiomas appropriately selected based on size, type, and location of dural attachment, and the eLTOA is a safe, rapid, and highly effective procedure with acceptable morbidity.

Lateral Transorbital Endoscope-Assisted Approach to the Cavernous Sinus

BACKGROUND AND OBJECTIVES

Surgical access to the cavernous sinus (CS) poses a unique challenge to the neurosurgeon given the concentration of delicate structures in the confines of a very small anatomic space. The lateral transorbital approach (LTOA) is a minimally invasive, keyhole approach that can provide direct access to the lateral CS.

METHODS

A retrospective review of CS lesions treated by a LTOA at a single institution was performed between 2020 and 2023. Patient indications, surgical outcomes, and complications are described.

RESULTS

Six patients underwent a LTOA for a variety of pathologies including a dermoid cyst, schwannoma, prolactinoma, craniopharyngioma, and solitary fibrous tumor. The goals of surgery (ie, drainage of cyst, debulking, and pathological diagnosis) were achieved in all cases. The mean extent of resection was 64.6% (±34%). Half of the patients with preoperative cranial neuropathies (n = 4) improved postoperatively. There were no new permanent cranial neuropathies. One patient had a vascular injury repaired endovascularly with no neurological deficits.

CONCLUSION

The LTOA provides a minimal access corridor to the lateral CS. Careful case selection and reasonable goals of surgery are critical to successful outcome.