The endonasal midline inferior intercavernous approach to the cavernous sinus: technical note, cadaveric step-by-step illustration, and case presentation

How I do it: Endoscopic endonasal resection of the medial wall of the cavernous sinus

BACKGROUND

Resection of the medial wall of the cavernous sinus (MWCSR) is a growing surgical maneuver for the radical removal of pituitary adenomas.

METHOD

We present a simple modification of the technique following the two dural layers of the floor of the sella turcica, allowing for early identification of the medial wall and simplifying dissection. We support this technique with an anatomical analysis on cadaveric specimens and clarifying dissection images.

CONCLUSION

Recognition and dissection of the dural unfolding of the floor of the sella turcica are "key points" that lower the risk and facilitate the MWCSR.

The Coexistence of Carotico-Clinoid Foramen and Interclinoidal Osseous Bridge: An Anatomo-Radiological Study With Surgical Implications

BACKGROUND AND OBJECTIVES

The coexistence of complete carotico-clinoid bridge (CCB), an ossification between the anterior (ACP) and the middle clinoid (MCP), and an interclinoidal osseous bridge (ICB), between the ACP and the posterior clinoid (PCP), represents an uncommonly reported anatomic variant. If not adequately recognized, osseous bridges may complicate open or endoscopic surgery, along with the pneumatization of the ACP, especially when performing anterior or middle clinoidectomies.

METHODS

According to Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews guidelines, a systematic scoping review was conducted up to June 5, 2023. PubMed, Scopus, Web of Science databases, and additional citations were searched. Two hundred high-resolution noncontrast computed tomography (CT) scans (400 sides) and 41 dry skulls (82 sides) were analyzed to identify the different morphology of sellar bridges, focusing on the coexistence of complete CCF and ICB. Two embalmed latex-injected heads with coexisting CCF and ICB were dissected step-by-step to show the anatomic relationship with the surrounding structures from an endoscopic and microscopic perspective.

RESULTS

A total of 19 articles were included. The review identified a complete CCF and ICB rate ranging from 4.92% to 6.3%. The analysis of 200 CT scans revealed a rate of coexistence in 4% of the cases, all encountered in White women. Two different types of interclinoid bridges were identified based on the degree of bone mineralization. Both endoscopic and macroscopic step-by-step dissections highlighted variability in morphology and consistency of the sellar bridges and the close relationship with the cavernous sinus neurovascular structures.

CONCLUSION

The coexistence of CCF and ICB is an anatomic variation found in 4% of cases. Preoperative knowledge of the degree of mineralization and its relationship with surrounding structures is essential to performing safe surgery and minimizing cranial nerve and vascular injuries. Preoperative high-resolution CT scans can adequately identify these anatomic variations.

Extended endoscopic endonasal approach to the chiasmatic cistern: An anatomical study of the arachnoid

This paper studied the arachnoid of the chiasmatic cistern (CC) and the methods for increasing the exposure of the CC from an endoscopic perspective. Eight anatomical specimens with vascular injection were used for endoscopic endonasal dissection. The anatomical characteristics of the CC were studied and documented, and anatomical measurements were collected. The CC is an unpaired five-walled arachnoid cistern located between the optic nerve, optic chiasm, and the diaphragma sellae. The average exposed area of the CC before the anterior intercavernous sinus (AICS) was transected was 66.67 ± 33.76 mm2 . After the AICS was transected and the pituitary gland (PG) was mobilized, the average exposed area of the CC was 95.90 ± 45.48 mm2 . The CC has five walls and a complex neurovascular structure. It is located in a critical anatomical position. The transection of the AICS and mobilization of the PG or the selective sacrifice of the descending branch of the superior hypophyseal artery can improve the operative field.

Endonasal endoscopic surgery for pituitary adenomas

Pituitary adenomas are slow-growing, benign intracranial tumors that can be characterized as functional (hormone-producing) or non-functional (non-hormone producing). Symptoms therefore arise from either endocrinologic abnormalities or mass effect on surrounding structures resulting in symptoms such as visual impairment and headache. In the last two decades, technical innovations have shifted surgical resection of such adenomas to endoscopic endonasal approaches. In this review, we describe the evolving approach to pituitary adenomas in the modern endoscopic era, including preoperative multidisciplinary review, relevant surgical anatomy, and a description of the technical nuances of standard and expanded approaches to the anterior skull base.

Intradural Pituitary Hemitransposition: Technical Note and Case Series Illustration

BACKGROUND AND OBJECTIVES

Lesions located in the retrosellar region, interpeduncular cistern, and petroclival region are among the most difficult to access in neurosurgery. Transcranial approaches are useful; however, the large distance between the surgeon and the lesion as well as the presence of major neurovascular structures surrounding the lesion may limit surgical exposure. A midline transsphenoidal route avoids transgression of the neurovascular plane and provides direct access to the interpeduncular cistern. To safely access the interpeduncular fossa, it requires mobilization of the pituitary gland. The pituitary hemitransposition technique permits mobilization of the gland, while preserving its venous drainage and arterial supply to the gland on one of its sides, preserving gland function. The authors aim to describe the intradural pituitary hemitransposition technique and to demonstrate its safe application for resection of skull base tumors in the retrosellar space.

METHODS

The authors describe the surgical technique and illustrate its application in 5 cases of different types of skull base tumors, including a video demonstrating all the steps to perform this approach. In addition, the authors discuss the advantages and limitations of this technique compared with other approaches to the retrosellar space.

RESULTS

The intradural pituitary hemitransposition technique was used to safely resect a chondrosarcoma, chordoma, craniopharyngioma, teratoma, and meningioma involving the parasellar and retrosellar spaces, while minimizing endocrine morbidity. We had one patient with mild, albeit permanent hyperprolactinemia and hypothyroidism after surgery. No other patients had permanent dysfunction related to surgery.

CONCLUSION

The endonasal endoscopic intradural pituitary hemitransposition approach is an effective technique for resection of lesions located within the retrosellar and petroclival regions, allowing adequate exposure while potentially optimizing the preservation of the pituitary function.

The "candy wrapper" of the pituitary gland: a road map to the parasellar ligaments and the medial wall of the cavernous sinus

PURPOSE

The anatomy of the medial wall of the cavernous sinus (MWCS) and parasellar ligaments (PLs) has acquired increasing importance in endoscopic endonasal (EE) surgery of the cavernous sinus (CS), including resection of the MWCS in functioning pituitary adenomas (FPAs). Although anatomical studies have been published, it represents a debated topic due to their complex morphology. The aim is to offer a description of the PLs that originate from the MWCS and reach the lateral wall of the cavernous sinus (LWCS), proposing the "candy wrapper" model. The relationships between the neurovascular structures and histomorphological aspects were investigated.

METHODS

Forty-two CSs from twenty-one human heads were studied. Eleven specimens were used for EE dissection; five underwent a microscopic dissection. Five specimens were used for histomorphological analysis.

RESULTS

Two groups of PLs with a fan-shaped appearance were encountered. The anterior group included the periosteal ligament (55% sides) and the carotico-clinoid complex (100% sides), formed by the anterior horizontal and the carotico-clinoid ligaments. The posterior group was formed by the posterior horizontal (78% sides), and the inferior hypophyseal ligament (34% sides). The periosteal ligament originated inferiorly from the MWCS, reaching the periosteal dura. The anterior horizontal ligament was divided in a superior and inferior branch. The superior one continued as the carotid-oculomotor membrane, and the inferior branch reached the CN VI. The carotico-clinoid ligament between the middle and anterior clinoid was ossified in 3 sides. The posterior horizontal ligament was related to the posterior genu and ended at the LWCS. The inferior hypophyseal ligament followed the homonym artery. The ligaments related to the ICA form part of the adventitia.

CONCLUSION

The "candy wrapper" model adds further details to the previous descriptions of the PLs. Understanding this complex anatomy is essential for safe CS surgery, including MWCS resection for FPAs.

Endoscopic Endonasal Resection of the Medial Wall of the Cavernous Sinus and Its Impact on Outcomes of Pituitary Surgery: A Systematic Review and Meta-Analysis

Introduction. Pituitary adenomas have the potential to infiltrate the dura mater, skull, and the venous sinuses. Tumor extension into the cavernous sinus is often observed in pituitary adenomas and techniques and results of surgery in this region are vastly discussed in the literature. Infiltration of parasellar dura and its impact for pituitary surgery outcomes is significantly less studied but recent studies have suggested a role of endoscopic resection of the medial wall of the cavernous sinus, in selected cases. In this study, we discuss the techniques and outcomes of recently proposed techniques for selective resection of the medial wall of the cavernous sinus in endoscopic pituitary surgery. Methods. We performed a systematic review of the literature using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and protocol and a total of 4 studies with 106 patients that underwent an endoscopic approach for resection of pituitary tumors with resection of medial wall from cavernous sinus were included. Clinical and radiological data were extracted (sex, mean age, Knosp, prior surgery, tumor size and type, complication rate, and remission) and a meta-analysis using the RevMan 5.4 software was performed. Results. A total of 5 studies with 208 patients were included in this analysis. The mean age of the study population was 48.87 years (range 25−82) with a female/male ratio of 1:1.36. Majority of the patients had Knosp Grade 1 (n = 77, 37.02%) and Grade 2 (n = 53, 25.48%). The complication rate was 4.81% (n = 33/106) and the most common complication observed was a new transient CN dysfunction and diplopia. Early disease remission was observed in 94.69% of the patients (n = 196/207). The prevalence rate of CS medial wall invasion varied from 10.4 % up to 36.7%. This invasion rate increased in frequency with higher Knosp Grade. The forest plot of persistent disease vs. remission in this surgery approach showed a p < 0.00001 and heterogeneity (I^2 = 0%). Discussion. Techniques to achieve resection of the medial wall of the cavernous sinus via the endoscopic endonasal approach include the “anterior to posterior” technique (opening of the anterior wall of the cavernous sinus) and the “medial to lateral” technique (opening of the inferior intercavernous sinus and). Although potentially related with improved endocrinological outcomes, these are advanced surgical techniques and require extensive anatomical knowledge and extensive surgical experience. Furthermore, to avoid procedure complications, extensive study of the patient’s configuration of cavernous ICA, Doppler-guided intraoperative imaging, surgical navigation system, and blunt tip knives to dissect the ICA’s plane are recommended. Conclusion. Endoscopic resection of the medial wall of the cavernous sinus has been associated with reports of high rates of postoperative hormonal control in functioning pituitary adenomas. However, it represents a more complex approach and requires advanced experience in endoscopic skull base surgery. Additional studies addressing case selection and studies evaluating long term results of this technique are still necessary.