Endoscopic endonasal approaches to the cavernous sinus

A primer to vascular anatomy of the brain: an overview on anterior compartment

PURPOSE

Knowledge of neurovascular anatomy is vital for neurosurgeons, neurologists, neuro-radiologists and anatomy students, amongst others, to fully comprehend the brain's anatomy with utmost depth. This paper aims to enhance the foundational knowledge of novice physicians in this area.

METHOD

A comprehensive literature review was carried out by searching the PubMed and Google Scholar databases using primary keywords related to brain vasculature, without date restrictions. The identified literature was meticulously examined and scrutinized. In the process of screening pertinent papers, further articles and book chapters were obtained through analysis and additional assessing of the reference lists. Additionally, four formalin-fixed, color latex-injected cadaveric specimens preserved in 70% ethanol solution were dissected under surgical microscope (Leica Microsystems Inc, 1700 Leider Ln, Buffalo Grove, IL 60089 USA). Using microneurosurgical as well as standard instruments, and a high-speed surgical drill (Stryker Instruments 1941 Stryker Way Portage, MI 49002 USA). Ulterior anatomical dissection was documented in microscopic images.

RESULTS

Encephalic circulation functions as a complex network of intertwined vessels. The Internal Carotid Arteries (ICAs) and the Vertebral Arteries (VAs), form the anterior and posterior arterial circulations, respectively. This work provides a detailed exploration of the neurovascular anatomy of the anterior circulation and its key structures, such as the Anterior Cerebral Artery (ACA) and the Middle Cerebral Artery (MCA). Embryology is also briefly covered, offering insights into the early development of the vascular structures of the central nervous system. Cerebral venous system was detailed, highlighting the major veins and tributaries involved in the drainage of blood from the intracranial compartment, with a focus on the role of the Internal Jugular Veins (IJVs) as the primary, although not exclusive, deoxygenated blood outflow pathway.

CONCLUSION

This work serves as initial guide, providing essential knowledge on neurovascular anatomy, hoping to reduce the initial impact when tackling the subject, albeit the intricate vasculature of the brain will necessitate further efforts to be conquered, that being crucial for neurosurgical and neurology related practice and clinical decision-making.

Endoscopic Reconstruction of the Anterior Skull Base Following Tumor Resection: Application of a Novel Bioabsorbable Plate

OBJECTIVE

Endoscopic repair of skull base defects is required following resection of intracranial pathology via the endoscopic endonasal approach (EEA). Many closure techniques have been described, but choosing between techniques remains controversial. We report outcomes of 560 EEA procedures of skull base reconstruction performed on 508 patients over a 15-year-period. Halfway through this period, we adopted the use of a rigid, bioabsorbable extrasellar plate for reconstruction, enabling a comparison between this technique and those used previously.

METHODS

All patients undergoing EEA from 2005 to 2019 at our institution were retrospectively reviewed. Demographic information, surgical pathology, tumor dimensions and radiographic features, reconstructive technique, and patient-related outcomes were collected and analyzed with univariate and multivariate statistical modeling.

RESULTS

Five-hundred sixty procedures were performed on 508 patients. The series complication rate was 8.2%. Overall, cerebrospinal fluid (CSF) leak rate was 5.0% but varied significantly across closure techniques (p < 0.001). Critically, the CSF leak rate in the 272 cases prior to our 2013 adoption of the Resorb-X Plate (RXP) was 8.5%, whereas leak rate in the subsequent 288 cases was 1.7%. RXP was protective against CSF leak (p = 0.001), whereas gross total resection (GTR) correlated with increased leak rate (p = 0.001). Patient BMI was significantly associated with risk of leak (p = 0.047). Other variables did not impact leak risk.

CONCLUSION

Reconstructive technique, extent of resection, and patient BMI significantly contributed to CSF leak rate. GTR was associated with increased leak risk while the RXP was protective. The bioabsorbable RXP is an effective option for rigid skull base repair with comparatively few complications.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:1092-1098, 2023.

From Above and Below: The Microsurgical Anatomy of Endoscopic Endonasal and Transcranial Microsurgical Approaches to the Parasellar Region

INTRODUCTION

The parasellar region is one of the most complex of the skull base. In this study, we review the anatomy and approaches to this region through a 360° perspective, correlating microsurgical and endoscopic anatomic nuances of this area.

METHODS

An endoscopic endonasal approach (EEA) and microsurgical dissections were performed. The parasellar anatomy is reviewed and common areas of tumor extensions are assessed. Surgical approaches are discussed based on the anatomic nuances of those regions.

RESULTS

The cavernous sinus (CS) can be divided into 2 spaces: posterosuperior, above and behind the internal carotid artery (ICA); and anterior, in front of the cavernous ICA. Those spaces can be approached through the CS walls: anterior and/or medial wall via EEA; or superior and/or lateral wall via transcranial approaches. The relationship of the Meckel cave, adjacent to the lateral and posterior wall of the CS, is relevant for surgical planning. Areas often affected by tumor extension can be divided into 6 regions: superior (cisternal), superolateral (parapeduncular), posterolateral (Meckel cave and petrous bone), medial (sella), anterior (superior orbital fissure), and anterior inferior (pterygopalatine fossa). Anatomic and technical nuances of each of those regions should be taken into consideration when dealing with tumors in the parasellar space.

CONCLUSIONS

A transcranial approach and EEA provide effective access to the parasellar region. Management of cavernous sinus and Meckel cave tumors requires familiarity with those approaches. Understanding of the surgical anatomy of the parasellar region, from above and below, is therefore necessary for adequate surgical planning and execution.

Anterior and Central Skull Base Tumors: Key Points for the Radiologist to Analyze Prior to Endoscopic Approaches

Initially developed as a minimally invasive technique to approach inflammatory conditions, transnasal endoscopic surgery has progressively expanded its anatomic targets and clinical indications. Consequently, numerous surgical approaches to the anterior and central skull base were developed, referred to as extended endonasal approaches (EEA). The intrinsic advantage of EEA is the exploitation of a natural corridor provided by sinonasal airspaces, with no need for skin incision and osteotomy and limited soft tissue damage. In this context, imaging plays essential role, demonstrating the relevant anatomic relationships of the lesion, the proper surgical corridor, the anatomic variants that may increase the surgical risk.

Outcomes and Complications of Aggressive Resection Strategy for Pituitary Adenomas in Knosp Grade 4 With Transsphenoidal Endoscopy

Surgery for pituitary adenomas (PAs) with cavernous sinus (CS) invasion in Knosp grade 4 is a great challenge and whether to adopt a conservative or aggressive surgical strategy is controversial. The aim of this study is to provide the outcomes and complications of an aggressive resection strategy for Knosp grade 4 PAs with transsphenoidal endoscopic surgery. Outcomes and complications were retrospectively analyzed in 102 patients with Knosp grade 4 PAs. Among them, primary PAs were seen in 60 patients and recurrent PAs were seen in 42 cases. Gross total resection (GTR) of the entire tumor was achieved in 72 cases (70.6%), subtotal tumor resection (STR) in 18 cases (17.6%), and partial tumor resection (PTR) in 12 cases (11.8%). Additionally, GTR of the tumor within the CS was achieved in 82 patients (80.4%), STR in 17 patients (16.7%), and PTR in 3 patients (2.9%). Statistical analyses showed that both recurrent tumors and firm consistency tumors were adverse factors for complete resection (P<0.05). Patients with GTR of the entire tumor were more likely to have favorable endocrine and visual outcomes than those with incomplete resection (P<0.05). Overall, the most common surgical complication was new cranial nerve palsy (n=7, 6.8%). The incidence of internal carotid artery (ICA) injury and postoperative cerebrospinal fluid (CSF) leakage was 2.0% (n=2) and 5.9% (n=6), respectively. Six patients (5.9%) experienced tumor recurrence postoperatively. For experienced neuroendoscopists, an aggressive tumor resection strategy via transsphenoidal endoscopic surgery may be an effective and safe option for Knosp grade 4 PAs.

Cavernous Sinus Meningioma with Orbital Involvement: Algorithmic Decision-Making and Treatment Strategy

Cavernous sinus meningioma (CSM) with orbital involvement presents a unique challenge to modern-day neurosurgeons. In the modern era of preventive medicine with enhanced screening tools, physicians encounter CSM more frequently. An indolent natural history, late clinical presentation, close proximity to vital neurovascular structures, poor tumor-to-normal tissue interface, and high risk of iatrogenic morbidity and mortality with aggressive resection add to the complexity of decision-making and optimal management of these lesions. The clinical dilemma of deciding whether to observe or intervene first for asymptomatic lesions remains an enigma in current practice. The concepts of management for CSM with orbital involvement have gradually evolved from radical resection to a more conservative surgical approach with maximal safe resection, with the specific goals of preserving function and reducing proptosis. This change in surgical attitude has enabled better long-term functional outcomes with conservative approaches as compared with functionally disabled outcomes resulting from the pursuit of anatomical cure from disease with radical resection. The advent of stereotactic radiosurgery as an adjunct tool to treat residual CSM has greatly shaped our resection principles and planning. Interdisciplinary collaboration for multimodality management is key to successful management of these difficult to treat lesions and tailor management as per individual's requirement.

Pituitary adenoma with posterior area invasion of cavernous sinus: surgical anatomy, approach, and outcomes

We found a series of Knosp grade 3A-4 pituitary adenomas in the posterior areas of the cavernous sinus (CS), a triangular-like structure on axial MRI. In this study, we dissected the surrounding neurovascular structure, discussed the surgical approach, and analyzed outcomes for patients with this invasion into this area. Eight embalmed adult cadaveric specimens were prepared for this study to demonstrate in detail the surgical anatomy related to this triangular-like structure. We used the "two points and one line" method to determine the surgical approach, and 35 cases with this area invasion were retrospectively reviewed. According to the endoscopic and microsurgical anatomy, the triangular-like structure appearing on the axial MRI is correlated with a square-based pyramid structure in the CS, and the upper surface is the posterior portion of the oculomotor triangle. A total of 37 posterior areas of the CS were involved in 35 patients. The accuracy of the "two points and one line" method in predicting the surgical approach is 86.5% (32/37). All three patients with Knosp 3A underwent gross total resection (GTR). Twenty (62.5%) patients with Knosp 4 underwent GTR, 9 (28.1%) patients underwent subtotal resection, and 3 (9.4%) patients underwent partial resection. Preoperative symptoms were alleviated to varying degrees, and no worsening occurred. Postoperative complications included two (5.7%) cases of cerebrospinal fluid leakage, one (2.9%) case of meningitis, two (5.7%) cases of permanent diabetes insipidus, and three (8.6%) cases of transient cranial nerve palsy. The "two points and one line" method is of great value in predicting the surgical approach of pituitary adenomas with CS invasion. The anatomic description of this particular square-based pyramid structure in the CS refines the understanding of pituitary adenomas with CS invasion.

Perioperative Considerations in Endoscopic Skull Base Surgery

Purpose of the Review

Present an overview of perioperative considerations specific to endoscopic skull base surgery necessary to maximize successful outcomes.

Recent Findings

The majority of perioperative considerations for endoscopic skull base surgery lack strong supporting evidence and frequently have varied use or implementation amongst institutions. A notable exception comes from a recent randomized controlled trial demonstrating the benefit of lumbar drainage in high-risk cerebrospinal fluid leaks.

Summary

Skull base surgeons must consider a multitude of perioperative factors. While many components of perioperative management are extrapolated from related fields such as endoscopic sinus surgery or open cranial base surgery, additional high-quality studies are needed to delineate best practices specific to endoscopic skull base surgery.

Cavernous sinus meningioma

Cavernous sinus meningioma (CSM) presents a management challenge to present-day neurosurgeons. Lack of adequate understanding of the natural history of these lesions, the early involvement of vital neurovascular structures, the absence of clear tissue planes with normal surrounding structures, and a high rate of aggressive surgery-related morbidity each pose management dilemmas for neurosurgeons. Over the past few decades, the enthusiasm of the neurosurgical community has shifted from aggressive microsurgical resection to maximal safe resection and institution of adjuvant radiotherapy, if necessary. This paradigm shift has ensured better functional outcome in treated patients. This chapter has been designed to discuss the current treatment algorithm and the importance of multimodality management for optimal outcome in patients with CSM. The technical aspects of this approach to management are presented, and the various treatment options are compared.

Resection of Pituitary Tumor with Lateral Extension to the Temporal Fossa: The Toothpaste Extrusion Technique

Transsphenoidal resection of the sellar and suprasellar lesions, whether microscopic or endoscopic, has been traditionally limited by tumors extending laterally to the carotid artery and cavernous sinus. Extended endoscopic or transmaxillary approaches may be warranted depending on these tumor extensions. We describe the use of an intraoperative Valsalva maneuver as a surgical adjunct to the transsphenoidal approach to improve the extent of resection for a favorable outcome. The patient was a 65-year-old woman who underwent resection of a giant pituitary tumor that extended laterally to the cavernous sinus to occupy a volume within the middle fossa. It was the senior author's impression that the lateral cavernous wall was intact at the time of surgery although this is difficult to determine definitively. After a transsphenoidal intrasellar resection of the intrasellar tumor, side-angled endoscopic visualization enabled identification of the breach in the medial cavernous wall where the tumor had invaded the cavernous sinus and ultimately grown into the middle fossa. A Valsalva maneuver was then applied, and the tumor was extruded from the cavernous sinus lateral to the carotid. The significant tumor was removed under direct visualization of the abducens nerve, which was well preserved. Postoperative imaging showed a sufficient extent of resection, and there were no postoperative complications. An intraoperative Valsalva maneuver can be a potentially useful technique for extending tumor resection in cases with a soft tumor and visualization of the opening within the cavernous sinus wall.

Reconstruction of the skull base in spontaneous rhinoliquorrhea

Objective/Hypothesis: Spontaneous rhinoliquorrhea often occurs due to defects of the skull base. It is often misinterpreted as rhinitis and is surgically the most difficult rhinoliquorrhea entity to close. Methods: We conducted a retrospective chart analysis of patients that were diagnosed with spontaneous rhinoliquorrhea at the University Hospital Bonn between 2001 and 2017. Results: Overall, twelve patients were included in this study. On average, the time between occurrence of nasal discharge and diagnoses of rhinoliquorrhea was 123 days. In ten patients, the localization of the skull base defect could be localized by computed tomography or MRI cisternography. Ten patients underwent surgery, of which 9 remained recurrence free. One patient underwent revision surgery and from thereon was recurrence free. Conclusion: Spontaneous rhinoliquorrhea still remains a diagnostic and therapeutic challenge. Whenever persistent watery nasal discharge appears in a patient, rhinoliquorrhea must be considered. Endoscopic surgical reconstruction of the skull base is the therapeutic gold standard and should be attempted as soon as the diagnosis is secured.

Direct Transcavernous Sinus Approach for Endoscopic Endonasal Resection of Intracavernous Sinus Tumors

OBJECTIVE

Because of its vascular supply and neurovascular contents, the cavernous sinus (CS) is a challenging area to dissect in the setting of skull base tumors with intracavernous extension or invasion. In the present study, we report the clinical outcomes of 14 patients with tumors with CS invasion that were surgically treated using a direct transcavernous sinus approach for endoscopic endonasal resection of their intracavernous sinus tumors.

METHODS

Fourteen patients had undergone surgery using a direct endoscopic endonasal transcavernous sinus approach. The pathologic entities included Knosp grade 3-4 pituitary adenomas (n = 8), meningioma (n = 3), squamous cell carcinoma (n = 2), and chondrosarcoma (n = 1). The indications, surgical technique, and outcomes are discussed.

RESULTS

Gross total resection was achieved in 11 patients (78.6%). All patients experienced resolution or improvement of symptoms. One patient experienced a transient oculomotor nerve palsy, which had resolved within 2 months postoperatively. No other complications occurred. For those tumors that had been grossly resected, no recurrence developed in any patient (mean follow-up, 40.4 ± 24.8 months; range 10-84).

CONCLUSIONS

Depending on the space created by intracavernous sinus tumors, use of the transanterior wall for the CS approach in endoscopic endonasal surgery could adequately treat most patients in our case series. This approach provided good visualization of the CS and can be used to treat tumors with favorable outcomes and a low incidence of complications in appropriately evaluated patients.

Technological and Ideological Innovations in Endoscopic Skull Base Surgery

BACKGROUND

Endoscopic skull base surgery has evolved over the last several decades due to technological advances and operative techniques. Several innovations that are not yet mainstream may have significant impact on the future of endoscopic skull base surgery.

METHODS

Current literature pertaining to innovations in endoscopic skull base surgery was retrieved using PubMed, Embase, Web of Science, and Google Scholar.

RESULTS

Several recent innovations may play an influential role in the advancement of endoscopic skull base surgery, including fluorescent dyes such as indocyanine green fluorescence, fluorescein, and 5-aminolevulinic acid, 3-dimensional endoscopes, robotic surgery, and intraoperative magnetic resonance imaging.

CONCLUSIONS

Several technologies are under current investigation with the hope to improve future outcomes in endoscopic skull base surgery. Additional research and evolution are necessary and will require intense scrutiny before becoming standard of care.

Management of Cavernous Sinus Involvement in Sinonasal and Ventral Skull Base Malignancies

Cavernous sinus (CS) involvement by sinonasal and ventral skull base malignancies is infrequently encountered in neurosurgical practice. Despite advancements in skull base microneurosurgery and endoscopic techniques, detailed knowledge and experience of the surgical management of these lesions are limited. This article elaborates on surgical strategies and approaches for CS involvement of malignant ventral skull base tumors. The article discusses the indications, techniques, nuances, advantages, limitations, and complications of minimally invasive CS biopsy, transcranial microscopic, and transfacial endoscopic approaches to the CS using illustrative diagrams and operative videos. The principles and nuances of a high-flow cerebral revascularization procedure are mentioned.

Reoperative endoscopic endonasal surgery for residual or recurrent pituitary adenomas

OBJECTIVE

Regrowth of the lesion after surgical removal of pituitary adenomas is uncommon unless subtotal resection was originally achieved in the first surgery. Treatment for recurrent tumor can involve surgery or radiotherapy. Locations of residual tumor may vary based on the original approach. The authors evaluated the specific sites of residual or recurrent tumor after different transsphenoidal approaches and describe the surgical outcome of endoscopic endonasal transsphenoidal reoperation.

METHODS

The authors analyzed a prospectively collected database of a consecutive series of patients who had undergone endoscopic endonasal surgeries for residual or recurrent pituitary adenomas after an original transsphenoidal microscopic or endoscopic surgery. The site of the recurrent tumor and outcome after reoperation were noted and correlated with the primary surgical approach. The chi-square or Fisher exact test was used to compare categorical variables, and the Mann-Whitney U-test was used to compare continuous variables between surgical groups.

RESULTS

Forty-one patients underwent surgery for residual/recurrent pituitary adenoma from 2004 to 2015 at Weill Cornell Medical College. The previous treatment was a transsphenoidal microscopic (n = 22) and endoscopic endonasal (n = 19) surgery. In 83.3% patients (n = 30/36) there was postoperative residual tumor after the initial surgery. A residual tumor following endonasal endoscopic surgery was less common in the sphenoid sinus (10.5%; 2/19) than it was after microscopic transsphenoidal surgery (72.7%; n =16/22; p = 0.004). Gross-total resection (GTR) was achieved in 58.5%, and either GTR or near-total resection was achieved in 92.7%. Across all cases, the average extent of resection was 93.7%. The rate of GTR was lower in patients with Knosp-Steiner Grade 3–4 invasion (p < 0.0005). Postoperative CSF leak was seen in only one case (2.4%), which stopped with lumbar drainage. Visual fields improved in 52.9% (n = 9/17) of patients and were stable in 47% (n = 8/17). Endocrine remission was achieved in 77.8% (n = 14/18) of cases, 12 by surgery alone and 2 by adjuvant medical (n = 1) and radiation (n = 1) therapy. New diabetes insipidus occurred in 4.9% (n = 2/41) of patients—in one of whom an additional single anterior hormonal axis was compromised—and 9.7% (n = 4/41) of patients had a new anterior pituitary hormonal insufficiency.

CONCLUSIONS

Endonasal endoscopic reoperation is extremely effective at removing recurrent or residual pituitary adenomas that remain after a prior surgery, and it may be preferable to radiation therapy particularly in symptomatic patients. Achievement of GTR is less common when lateral cavernous sinus invasion is present. The locations of residual/recurrent tumor were more likely sphenoidal and parasellar following a prior microscopic transsphenoidal surgery and sellar following a prior endonasal endoscopic surgery.

Endoscopic Endonasal Surgery for Tumors of the Cavernous Sinus: A Series of 234 Patients

BACKGROUND

Cavernous sinus (CS) tumors often are considered inoperable. We present our experience with endoscopic endonasal surgery (EES) and compare the outcomes for different tumor.

METHODS

EES (medial or lateral approach) was used in 234 patients with CS tumors. The cohort included 175 (75%) pituitary adenomas and 59 (25%) nonadenomatous lesions.

RESULTS

Presenting symptoms were significantly different between the 2 groups, with cranial neuropathies occurring mainly in nonadenomas (P < 0.0001). The overall gross total tumor resection rate from the CS was 37.3% (37.1% in adenomas, 38.1% in non-adenomas). In total, preexisting cranial nerve (CN) dysfunction improved in 56.4% of the patients. After treatment completion (including radiation of residual tumor), 83.3% of acromegalic patients, 50% of prolactinomas and 33.3% of Cushing's disease, were in remission. Visual loss improved in 86.8% of adenomas and in 70.8% of nonadenomas. Intracavernous CN palsies improved in 77.3% of adenomas and 42.4% of nonadenomas. New permanent CN palsies occurred in 7 nonadenomas, which is significantly greater than in adenomas (P = 0.007). The leak rate of cerebrospinal fluid was 6.3% for adenomas and 11.9% for nonadenomas. Four patients suffered an internal carotid artery injury with no neurologic sequelae in 3 cases and 1 death (0.4%).

CONCLUSIONS

EES provides an easily accessible midline corridor to the CS with equivalent or superior results to transcranial approaches in the management of select tumors. Symptomatology due to CS invasion is more likely to improve in pituitary adenomas and the rate of surgical complications is greater in nonadenomas. Using a team approach, the overall mortality due to vascular injury is low.

Endoscopic endonasal surgery for nonadenomatous, nonmeningeal pathology involving the cavernous sinus

OBJECTIVE Surgery within the cavernous sinus (CS) remains a controversial topic because of the delicate and complex anatomy. The risk also varies with tumor consistency. Softer tumors such as pituitary adenomas are more likely to be surgically treated, while firm tumors such as meningiomas are often treated with radiosurgery. However, a wide range of pathologies that can involve the CS are amenable to surgery. The authors describe and analyze their results using endonasal endoscopic "medial-to-lateral" approaches for nonadenomatous, nonmeningeal tumors, in relation to the degree of invasion within the CS. METHODS A prospectively acquired database of consecutive endoscopic approaches for tumors with verified intraoperative CS invasion was reviewed. Pituitary adenomas and meningiomas were excluded. Degree of invasion of the CS was classified using the Knosp-Steiner (KS) grading system as well as the percentage of cavernous carotid artery (CCA) encasement. Extent of resection of the entire tumor and of the CS component was assessed by independent neuroradiologists using volumetric measurements of the pre- and postoperative MRI studies. Demographic data and complications were noted. RESULTS Fifteen patients (mean age 51.1 years who received endoscopic surgery between 2007 and 2013 met the selection criteria. There were 11 malignant tumors, including chordoma, chondrosarcoma, hemangiopericytoma, lymphoma, and metastatic cancer, and 4 benign tumors, including 3 cavernous hemangiomas and 1 dermoid. All cases were discussed before treatment in a tumor board. Adjuvant treatment options included chemotherapy and radiotherapy. The mean pre- and postoperative tumor volumes were 12.74 ml and 3.86 ml. Gross-total resection (GTR; ie, resection greater than 95%) was the goal in 13 cases and was achieved in 6 patients (46%) while in addition 5 patients had a greater than 80% resection. Gross-total resection in the CS was accomplished in 55% of the tumors with KS Grades 1-2 and in 16.6% of the tumors with KS grades 3-4, respectively. Likewise, GTR was accomplished in 55% of the tumors with CCA encasement under 75% and in 14.3% of the lesions with CCA encasement over 75%, irrespective of tumor volume and underlying pathology. There were 18 preexisting cranial neuropathies involving cranial nerves III-VI, of which 9 fully resolved, 4 improved, and 3 remained unchanged; 2 of these worsened with tumor recurrence. Surgical complications included 1 transient new cranial nerve VI palsy associated with Horner's syndrome and 1 case of panhypopituitarism. There were no postoperative CSF leaks and no infections. The mean extended follow-up was 34.4 months. CONCLUSIONS Endonasal endoscopic approaches can play a role in the management of nonmeningeal, nonadenomatous tumors invading the CS, either through biopsy, debulking, or GTR. An advantage of this method is the relief of preexisting cranial neuropathies with low risk for new neurological deficit. Extent of resection within the CS varies with KS grade and degree of carotid encasement irrespective of the underlying pathology. The goals of surgery should be clearly established preoperatively in consultation with radiation and medical oncologists.

Sensitivity and specificity of intrathecal fluorescein and white light excitation for detecting intraoperative cerebrospinal fluid leak in endoscopic skull base surgery: a prospective study

OBJECT

The intraoperative detection of CSF leaks during endonasal endoscopic skull base surgery is critical to preventing postoperative CSF leaks. Intrathecal fluorescein (ITF) has been used at varying doses to aid in the detection of intraoperative CSF leaks. However, the sensitivity and specificity of ITF at certain dosages is unknown.

METHODS

A prospective database of all endoscopic endonasal procedures was reviewed. All patients received 25 mg ITF diluted in 10 ml CSF and were pretreated with dexamethasone and Benadryl. Immediately after surgery, the operating surgeon prospectively noted if there was an intraoperative CSF leak and fluorescein was identified. The sensitivity, specificity, and positive and negative predictive power of ITF for detecting intraoperative CSF leak were calculated. Factors correlating with postoperative CSF leak were determined.

RESULTS

Of 419 patients, 35.8% of patients did not show a CSF leak. Fluorescein-tinted CSF (true positive) was noted in 59.7% of patients and 0 false positives were encountered. CSF without fluorescein staining (false negative) was noted in 4.5% of patients. The sensitivity and specificity of ITF were 92.9% and 100%, respectively. The negative and positive predictive values were 88.8% and 100%, respectively. Postoperative CSF leaks only occurred in true positives at a rate of 2.8%.

CONCLUSIONS

ITF is extremely specific and very sensitive for detecting intraoperative CSF leaks. Although false negatives can occur, these patients do not appear to be at risk for postoperative CSF leak. The use of ITF may help surgeons prevent postoperative CSF leaks by intraoperatively detecting and confirming a watertight repair.

Microsurgical and histological identification and definition of an interdural incision zone in the dorsolateral cavernous sinus

OBJECTIVES

The anatomy of the cavernous sinus is described controversially in a number of publications. In the present cadaveric study, the architecture of the dorsolateral wall of the cavernous sinus is studied microsurgically and histologically.

MATERIALS AND METHODS

Twenty cadaveric skulls have been dissected through a classical surgical frontotemporal approach. The temporal skull base was flattened and anatomical landmarks like the meningo-orbital band, superior orbital fissure, foramina rotundum, ovale, and spinosum were identified. Lateral of the trigeminal foramina, the dura was cut and the periosteal dural layer was separated from the meningeal layer, identifying an interdural zone. The length and the extent of this zone were evaluated. The dural architecture of the interdural incision zone was examined histologically.

RESULTS

In all specimens, two dural layers lateral of the trigeminal foramina could be separated. The identified interdural incision zone extended in a length of 3.8-6.4 cm in the antero-posterior direction. The zone could be followed medially to the superior orbital fissure for 5.3 mm and lateral of the foramen spinosum for 6.4 mm. The separation of the dural layers allowed the approach to the superior border of the cavernous sinus through this interdural incision zone. The histological analysis of the interdural incision zone showed clearly the existence of two dural layers.

CONCLUSIONS

The architecture of the temporal-fossa-dura allows the microsurgical separation of two meningeal dural layers through a length of 5-6 cm next to the trigeminal foramina. Opening this interdural incision zone allowed exploring the superior border of the cavernous sinus.

Endoscopic endonasal transsellar approach for laterally extended pituitary adenomas: volumetric analysis of cavernous sinus invasion

PURPOSE

The authors conducted a statistical analysis of surgical results of the endoscopic endonasal transsellar approach to provide quantitative indices for selection of the approach in the treatment of laterally extended pituitary adenomas.

METHODS

Surgical results of 25 patients with laterally extended pituitary adenomas of Knosp grade 3 or 4 were retrospectively analyzed. The removal rate was evaluated by the volumetric change of the lateral tumor compartment.

RESULTS

The transsellar approach was used exclusively in all cases. Gross total removal of the lateral tumor compartment was achieved in 14 (56.0%). Factors affecting the tumor removal through the transsellar approach were lateral tumor volume (p = 0.006), maximal distance to the cavernous sinus outer wall (p = 0.004) and history of previous surgery (p = 0.017). The cut-off values for the lateral tumor volume and maximal distance to the cavernous sinus outer wall predicting the gross total removal were 0.479 ml and 8.1 mm, respectively. The surgical complications of the transsellar approach included each case of anterior lobe function insufficiency and liquorrhea.

CONCLUSIONS

The transsellar approach is adequate for removal of lateral tumor compartment in the majority of cases with laterally extended pituitary adenomas. The tumor compartments dorsal and ventral to the horizontal portion of the intracavernous carotid artery are amenable to the removal. But for removal of the tumor compartment lateral to the carotid siphon requires additional use of the parasellar approach.

Resection of the intracavernous sinus tumors using a purely endoscopic endonasal approach

Resection of the cavernous sinus (CS) lesions has been a surgical challenge because the anatomy of the CS presents a high grade of complexity. This report describes the feasibility of the purely endoscopic endonasal approach to the CS. Twenty-five patients with intracavernous sinus tumors were treated with a purely endoscopic endonasal approach. The indications, efficacy, surgical techniques, and complications of this approach were discussed. Gross total resection occurred in 19 cases (76%), subtotal resection occurred in 2 cases (8%), and partial resection occurred in 4 cases (16%) including pituitary adenoma in 10 cases (total 70%; subtotal 10%; partial 20%), meningioma in 6 cases (total 66.6%; subtotal 16.7%, partial 16.7%), schwannoma in 5 cases (100%, total 5), malignant tumor in 4 cases (total 75%; subtotal 25%). All patients experienced resolution or improvement of symptoms. No patient experienced intraoperative complication and new neurological deficit. Only 1 case of postoperative cerebrospinal fluid leakage repaired via endoscopic endonasal approach on the 14th day after the surgery. The purely endoscopic endonasal approach to the CS in appropriately evaluated patients can be used to address a wide variety of benign and malignant tumor pathology with favorable outcomes and a low incidence of complications.

Corridor-based endonasal endoscopic surgery for pediatric skull base pathology with detailed radioanatomic measurements

BACKGROUND

Pediatric anatomy is more restricted, and the propagation of endonasal endoscopic approaches in the pediatric population has been limited.

OBJECTIVE

To demonstrate the feasibility of the endonasal endoscopic approach in a variety of age groups and to perform measurements of the corridors and spaces available for surgery as a guide for case selection.

METHODS

Only patients <18 years were included. The choice of operative corridor/approach is described in relation to pathological entity and location. Preoperative/postoperative visual fields and endocrine panels, extent of resection, as well as postoperative long-term complications are described. Prospective magnetic resonance image-based anatomic measurements of key distances were performed to determine age-dependent surgical indications and limitations.

RESULTS

Forty purely endoscopic procedures were performed in 33 pediatric patients (5-18 years of age) harboring a variety of skull base lesions, from benign tumors to congenital malformations. For the 20 patients in whom gross total resection was the intended goal of surgery, gross total resection was attained in 15 (75%). There were 2 infections (5%) and no cerebrospinal fluid leaks. Significant improvement was shown in 58.3% of patients with visual deficits. Hormone overproduction resolved in 75% of patients, while preoperative hormone insufficiency only improved in 29.2%. Wider intercarotid distance at the superior clivus (P = .01) and shorter nare-dens working distance (P = .001) predicted improved outcomes and fewer postoperative complications.

CONCLUSION

Endonasal endoscopic skull base approaches are viable in the pediatric population, they are not impeded by sphenoid sinus aeration, and they have minimal risk of cerebrospinal fluid leak and meningitis. Outcomes and complications can be predicted based on specific radio anatomical skull base measurements rather than age.

Endoscopic endonasal anatomical study of the cavernous sinus segment of the ophthalmic nerve

OBJECTIVES/HYPOTHESIS

This cadaveric study analyzes the endoscopic endonasal anatomy of the ophthalmic division of the trigeminal nerve (V1 ), from the middle fossa to its orbital entry via the superior orbital fissure. Anatomical relationships with the surrounding cranial nerves and blood vessels are described, with emphasis on their clinical correlation during surgery in this region. Our objective was to describe the anatomical relationships of the ophthalmic division of the trigeminal nerve.

STUDY DESIGN

Cadaveric study.

METHODS

Thirty middle cranial fossae, in adult human cadaveric specimens, were dissected endonasally under direct endoscopic visualization. During the dissection, we noted the relationships of the V1 nerve with the other trigeminal branches, as well as with the oculomotor and trochlear nerves, the paraclival and cavernous portions of the internal carotid artery, and the superior orbital fissure (SOF).

RESULTS

The V1 nerve is the most superior trigeminal branch and runs upward and obliquely, along the middle portion of the lateral wall of the cavernous sinus. The V1 nerve joins the oculomotor and trochlear nerves to exit the cavernous sinus and enter the orbit through the SOF. Ten percent of the specimens displayed the trochlear nerve running along as a mate of the V1 nerve. The V1 nerve borders two key triangles in the lateral wall of the cavernous sinus, and the Parkinson's and anteromedial triangles.

CONCLUSIONS

In this study, the V1 nerve was a constant and reliable landmark, thus allowing the identification of the anteromedial triangle. This potential space can serve as an adequate window to access the temporal lobe. Knowledge of this anatomy is essential when planning and executing endonasal surgery in this region.

LEVEL OF EVIDENCE

NA.

Optic canal (OC) and internal carotid artery (ICA) in sellar region

PURPOSE

OC and ICA are important structures in sellar region, the injury of ICA and optic nerve can be the severe complications in the operations related to sellar region such as the transsphenoidal surgery and extended transsphenoidal surgery. So knowing their position and their relationship to stable structures in sellar region is of great importance. The aim of our study is to provide specific and comprehensive data about the location of OC and ICA in sellar region in order to guide the surgeons through difficulties in surgeries related to sellar region.

METHODS

Computer topographic angiography (CTA) images of 200 individuals were reviewed, the measurement was performed on coronal, sagittal and axis planes after multiplanar reformation (MPR). We located OC by the tubercular recess (TR) and the top edge of sphenoid sinus, we located ICA by the midpoint of sellar floor (SF) and the top edge of sphenoid sinus.

RESULT

OC can be located by TR and the distance between OC and sagittal midline; ICA can be located by midpoint of SF and distance between ICA and sagittal midline; ICA has stationary relationship to ACP.

CONCLUSION

Knowing the anatomical position of OC and ICA and the positional relationship between them and the sellar region is of great importance in the surgeries related to the sellar region such as the trans-sphenoidal approach to pituitary and extended transsphenoidal surgery to non-pituitary adenoma lesions.

Endoscopic endonasal access to the jugular foramen: defining the surgical approach

Introduction The endoscopic endonasal approach to the parapharyngeal space (PPS) and jugular foramen is not well defined. We sought to systematically define the important landmarks and limitations of this new surgical technique using an endoscopic transmaxillary transpterygoid corridor. Methods Endoscopic dissection was performed in both sides of two latex-injected cadaver heads. Left-sided dissections were facilitated by the addition of a sublabial maxillary antrostomy. The pterygopalatine fossa, infratemporal fossa, and PPS were sequentially dissected and the endoscopic perspective was examined. Measurements were obtained from the surgical orifices to the upper cervical internal carotid artery (ICA) and internal jugular vein (IJV). Results Successful access to the PPS and jugular foramen was achieved in each dissection. The lateral pterygoid plate, mandibular branch of the trigeminal nerve, middle meningeal artery, levator veli palatini muscle, Eustachian tube, and stylopharyngeal fascia were identified as landmarks for the upper cervical ICA and the IJV. The mean distance from the nasal sill was markedly greater than from an ipsilateral sublabial antrostomy. Conclusion The endoscopic endonasal approach can provide adequate access to the PPS, carotid sheath, and jugular foramen. Multiple landmarks are useful to guide the dissection within these deep spaces and may facilitate the clinical application of this approach.