Intracranial Breakthrough Through Cavernous Sinus Compartments: Anatomic Study and Implications for Pituitary Adenoma Surgery

Neurosurgery for the rhinologist

PURPOSE OF REVIEW

The purpose of this review is to provide a comprehensive anatomical appraisal of the neurosurgical anatomy exposed through the endonasal and paranasal sinuses routes, focusing on the most common expanded endonasal approaches (EEAs) as well as recent advances in this surgical field.

RECENT FINDINGS

The EEAs are redefining the management of skull base pathology. Neurovascular structures previously considered a limitation, can be now approached through these surgical corridors. Advances in this field include the development of new surgical techniques and routes that allow better visualization and access to pathologies located in the ventral skull base. Understanding the surgical anatomy related to EEAs is essential not only for neurosurgeons but also for rhinologists.

SUMMARY

Knowledge of the surgical anatomy of the most common EEAs that utilize paranasal sinuses as a surgical corridor enables more effective management of complex skull base pathologies. Comprehensive anatomical knowledge of these corridors and the surrounding neurovascular structures is crucial to maximize benefits of EEAs and improve outcomes.

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.

Regulation of long noncoding RNAs in the pathogenesis and clinical implications of pituitary adenomas

BACKGROUND

Pituitary adenoma (PA) is a type of tumor that develops in the sella turcica and is one of the most frequent intracranial tumors. It belongs to a type of adenoma derived from a single clone of cells in the pituitary gland. PA ranks third among all intracranial tumors, following only gliomas and meningioma. The average prevalence rate is approximately 15% at autopsy and 22.5% at radiological examinations.

OBJECTIVE AND SIGNIFICANCE

Most PAs are benign and non-invasive adenomas that can be removed surgically or controlled with medication. However, approximately 35% of them show invasion into nearby anatomical structures and cannot be completely resected. 0.1%~0.2% of PA cases eventually develop into pituitary carcinomas. Additionally, PA may cause severe morbidity due to mass effects and the disorder of pituitary hormone secretion. Therefore, there is an urgent need to clarify the pathological mechanism of PA, improve the accuracy of diagnosis, and develop targeted therapies.

RESEARCH STATUS

Although current knowledge about the pathogenesis of PA remains limited, epigenetic modulation of PA has been increasingly implicated. Long non-coding RNAs (lncRNAs) are known to regulate gene expression post-transcriptionally and exert substantial roles in the initiation, progression, or suppression of various tumors. Accumulating evidence has shown close relationships between lncRNA dysregulation and PA development.

CONCLUSIONS

This review highlights recent progress in the study of lncRNAs in PA pathogenesis and their potential as diagnostic/prognostic biomarkers or therapeutic targets for PA patients.

Two- and three-dimensional endoscopic endonasal surgery of large and giant pituitary adenomas-outcome analysis of a series of 62 patients from a single pituitary center

To analyze the perioperative course and clinical outcome of patients with large (lPA) and giant (gPA) pituitary adenoma who underwent endoscopic endonasal transsphenoidal surgery (EETS) using either two-dimensional (2D-E) or three-dimensional (3D-E) endoscopic systems. Single-center retrospective study of consecutive patients with lPA and gPA who underwent EETS between November 2008 and January 2023. LPA were defined as ≥ 3 cm and < 4 cm in diameter in at least one dimension and a volume of ≥ 10ccm; gPA were defined as larger than 4 cm in diameter and with a greater volume than 10ccm. Patient data (age, sex, endocrinological and ophthalmological status) and tumor data (histology, tumor volume, size, shape, cavernous sinus invasion according to the Knosp classification) were analyzed. 62 patients underwent EETS. 43 patients were treated for lPA (69.4%) and 19 patients for gPA (30.6%). 46 patients (74.2%) underwent surgical resection using 3D-E and 16 patients 2D endoscopy (25.8%). Statistical results are referred to the comparison between 3D-E and 2D-E. Patients' age ranged from 23-88 years (median 57), 16 patients were female (25.8%), 46 male (74.2%). Complete tumor resection was possible in 43.5% (27/62), partial resection in 56.5% (35/62). Resection rates did not differ between 3D-E (27 patients [43.5%]) and 2D-E (7 patients [43.8%], (p = 0.985). Visual acuity improved in 30 of 46 patients with preoperative deficit (65.2%). In the 3D-E group 21 of 32 patients (65.7%) improved, compared to 9 of 14 patients in the 2D-E group (64.3%). Improvement of visual field was achieved in 31 of 50 patients (62.0%; 22 of 37 patients in the 3D-E group [59.4%] and 9 of 13 patients in the 2D-E group [69.2%]). CSF leak was the most frequent complication and occurred in 9 patients (14.5%, [8 patients 17.4% 3D-E]) without statistical significance. Other surgical complications like postoperative bleeding, infection (meningitis) and deterioration of visual acuity and field were detected without statistical difference. New pituitary anterior lobe dysfunction was observed in 30 of 62 patients (48.4%, 8 patients [50.0%] in the 2D-E group and 22 patients [47.8%] in the 3D-E group). A transient deficit of posterior lobe was detected in 22.6% (14/62). No patient died within 30 days of surgery. Although 3D-E may improve surgical dexterity, in this series of lPA and gPA it was not associated with higher resection rates compared to 2D-E. However, 3D-E visualization during resection of large and giant PA is safe and feasible and patient's clinical outcome is not different compared to 2D-E.

Pituitary adenoma with cavernous sinus compartment penetration and intracranial extension: surgical anatomy, approach, and outcomes

Objectives

To understand the different characteristics and growth corridors of knosp grade 4 pituitary adenomas (Knosp4PA) with cavernous sinus (CS) compartments penetration and intracranial extension, aiming to improve the safety, effectiveness, and total resection rate of surgery.

Methods

A case series of 120 Knosp4PA patients with 187 invaded compartments were retrospectively reviewed. A novel surgery-relevant grading system was proposed according to the CS penetrating features. The details of approach drafting, risk prediction, and complication avoidance were analyzed and integrated through illustrated cases.

Results

All enrolled tumor was Knosp4PA which was derived from Knosp subgrades 3A(62.5%) and 3B(37.5%). Based on the tumor growth pathway and its relevant features, five subclassifications of intracranial extension(n=98,81.7%) were classified, which derived from the superior (Dolenc's and Oculomotor subtype, 5% and 24.2%), lateral (Parkinson's subtype,18.3%), and posterior (cerebral peduncle and Dorello's subtype, 5.8% and 1.7%) CS compartment penetration. The size of intracranial extension is assessed by Lou's scale proposed here based on preoperative MRI characteristics. Under Lou's scale, the gross total rate (GTR) decreased (82%, 53%, 22%, and 19%) with grades increased (grade 0,1,2,3, respectively), and presents significant difference between the four groups (p=0.000), as well as between single and multiple compartments involved (p=0.001). Preoperative cranial nerve deficits included the optic nerve (53%), oculomotor nerve (24.2%), and abducent nerve (4.2%), with an overall rate of visual function improvement in 68.1%. Postoperative complications of transient diabetes insipidus, cerebrospinal fluid (CSF) leakage, and cranial nerve deficits were 6.7%, 0.8%, and 0%. No new cranial nerve deficits occurred. The mortality rate was 0.8%.

Conclusion

The concept of "penetration" refines the extracavernous growth pattern, and the five intracranial subclassifications help to understand the potential extension corridors, enhancing adequate exposure and targeted resection of Knosp4PA. This grading system may benefit from its predictive and prognostic value, from which a higher GTR rate can be achieved.

Efficacy of a Novel Augmented Reality Navigation System Using 3D Computer Graphic Modeling in Endoscopic Transsphenoidal Surgery for Sellar and Parasellar Tumors

In endoscopic transsphenoidal skull base surgery, knowledge of tumor location on imaging and the anatomic structures is required simultaneously. However, it is often difficult to accurately reconstruct the endoscopic vision of the surgical field from the pre-surgical radiographic images because the lesion remarkably displaces the geography of normal anatomic structures. We created a precise three-dimensional computer graphic model from preoperative radiographic data that was then superimposed on a visual image of the actual surgical field and displayed on a video monitor during endoscopic transsphenoidal surgery. We evaluated the efficacy of this augmented reality (AR) navigation system in 15 consecutive patients with sellar and parasellar tumors. The average score overall was 4.7 [95% confidence interval: 4.58-4.82], which indicates that the AR navigation system was as useful as or more useful than conventional navigation in certain patients. In two patients, AR navigation was assessed as less useful than conventional navigation because perception of the depth of the lesion was more difficult. The developed system was more useful than conventional navigation for facilitating an immediate three-dimensional understanding of the lesion and surrounding structures.

The Oculomotor Cistern and Its Role in the Management of Pituitary Lesions: An Anatomical, Radiographic, and Clinical Scoping Review

BACKGROUND

The oculomotor cistern (OMC) is a cerebrospinal fluid space bound by meningeal layers that surrounds the oculomotor nerve as it crosses the oculomotor triangle to reach the lateral wall of the cavernous sinus at the level of the anterior clinoid process. Although several anatomical and radiological studies are available, its anatomy and relationship with pituitary adenomas (PAs) are still matter of discussion.

OBJECTIVE

The aim of the study is to provide an updated and focused overview of the OMC, highlighting the different perspectives and descriptions from anatomical, radiological, and clinical points of view.

METHODS

A scoping review was conducted up to 29^th October 2022, according to PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) criteria. PubMed, Web of Science, Scopus databases, and correlated citations were investigated.

RESULTS

Of the 562 records identified, 22 were included in the present analysis. There were 13, 5, and 4 anatomo-surgical, radiological, and clinical studies, respectively. Though there is general consensus on its definition, data are variable on different features of OMC. Defects or absence of dural layers adjacent to the oculomotor nerve were described in only 4 papers. The transition from meningeal to neural layers is still unclear. PAs with OMC involvement are poorly studied and have unique clinical characteristics. To date, 21 patients have been described; the reported prevalence of OMC involvement by PAs ranges from 4.1% to 14.6%.

CONCLUSIONS

Clarifying the OMC features with further systematic studies may not only broaden theoretical knowledge but also have implications on endoscopic transnasal pituitary surgery.

Expanded endoscopic endonasal transsphenoidal approach to determine morphological characteristics and clinical considerations of the cavernous sinus venous spaces

The study aimed at investigating the morphological characteristics and interconnected regularities of the cavernous sinus (CS) venous spaces using an expanded endoscopic endonasal transsphenoidal approach. Surgical dissections were performed for 15-colored silicon-injected human head specimens. The CS venous spaces were examined for their morphological and clinical characteristics using an expanded endoscopic endonasal transsphenoidal approach. The intracavernous course of the internal carotid artery (ICA) divided the CS venous spaces into four interconnected virtual compartments: medial, anteroinferior, posterosuperior, and lateral. The CS venous spaces had peculiar morphological characteristics; the medial compartment was C-shaped while the anteroinferior compartment resembled a boat's bow. The mean distances from the medial border of the inferior horizontal segment of cavernous ICA to the mid-line of the pituitary gland (PG) were 6.07 ± 1.61 mm (left) and 5.97 ± 1.89 mm (right); the mean distances from the medial border of the subarachnoid segment of cavernous ICA to the mid-line of the PG were 5.77 ± 1.16 mm (left) and 5.63 ± 1.17 mm (right); the mean distances from the medial border of the anterior vertical segment of cavernous ICA to the mid-line of the PG were 10.27 ± 1.74 mm (left) and 10.47 ± 1.90 mm (right). Morphological characteristics and the knowledge of the interconnected regularities of the CS venous spaces may help surgeons accurately locate the neurovascular structure, and thus may contribute to the effective prediction of tumor invasion and extension during endoscopic CS surgery.