Circumferential exposure of the cavernous sinus and parasellar region through a combined open and endoscopic endonasal transcavernous approach, a morphometric study.

INTRODUCTION: Although recent trends currently favor the endoscopic endonasal transcavernous approach (EETA) over the pretemporal transcavernous approach (PTA) for certain cavernous sinus pathologies, dedicated assessment of the surgical exposure and maneuverability is wanting. Toward this aim, this morphometric study quantifies these variables within four cavernous sinus compartments by comparing the PTA, EETA, and a combined approach to achieve a circumferential dissection (EETA-PTA). MATERIAL: In five latex-injected specimens, exposure volumes of the EETA, PTA, and circumferential EETA-PTA approaches were quantified; the latter combined the most conservative options of both the endoscopic and open approaches. Two clinical cases illustrate the combined approach. RESULTS: EETA-PTA provided the largest volume of exposure (65.6% vs 35% PTA vs 44.6% EETA, P = 0.01) and eliminated the need to mobilize the ICA or cross cranial nerves. Although EETA and PTA approaches afforded comparable exposure volumes along the entire cavernous sinus (34.9 vs 44.6%), the EETA better exposed medial and inferior compartments (whereas the PTA exposed larger volumes in the lateral and superior compartments. The combined EETA-PTA yielded 66% of total cavernous sinus exposure volumes and eliminated the need to mobilize the ICA or cross cranial nerves. CONCLUSIONS: Our methodology aligns with strategies that use a modular concept to divide the skull base into compartments for maximal safe resection. Excluding soft tumors, the EETA is preferred for medial and inferior lesions and the PTA for superior and lateral lesions. A staged combined EETA-PTA may safely yield a 360-degree access for extensive multi-compartment lesions that span neurovascular structures within the cavernous sinus.

Mullan's triangle or anteromedial triangle of the middle cranial fossa: a cadaveric study with its surgical importance.

BACKGROUND: Surgical approaches to the cavernous sinus (CS) and middle cranial fossa (MCF) can be challenging, particularly for young neurosurgeons. The anteromedial (Mullan's) triangle is a triangle by the side of the CS and constitutes part of the floor of the MCF. The contents include the sphenoid sinus, superior ophthalmic vein, and sixth cranial nerve. The literature contains very little research that has precisely defined and measured the anteromedial triangle while considering anatomical variances minimally. METHODOLOGY: The present study was conducted on the skulls of 25 adult human cadavers which were dissected to expose the anteromedial (Mullan's) triangle on both sides. After precisely defining the triangle on each side, measurements of the three borders were taken, and using Heron's formula, the area of each triangle was calculated. RESULTS: On average, the length of the medial border was 12.5 (+ 3.1 mm); the length of the lateral border was 9.9 (+ 3.1 mm); the length of the base was 10.75 (+ 2.4 mm) and the area of the anteromedial triangle was 43.9 (+ 15.06 mm2). CONCLUSION: Precise anatomical knowledge of the Mullan's triangle enables the treatment of disorders in often deformed anatomy or difficult-to-access structures. That is the reason it is important to gain a thorough understanding of the surgical anatomy and to adopt a safe procedure.

Recovery of cranial nerve neuropathies after LINAC-based stereotactic radiosurgery for benign cavernous sinus meningioma.

PURPOSE: Cranial Nerve Neuropathies (CNNs) often accompany Cavernous Sinus Meningioma (CSM), for which Stereotactic Radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSR) are established treatments. This study assesses CNNs recovery in CSM patients treated with LINAC, offering insight into treatment effectiveness. METHODS: This study was conducted on 128 patients with CSM treated with LINAC-based SRS/FSR between 2005 and 2020 at a single institution. 46 patients presented with CNNs. The study analyzed patients' demographics, clinical parameters, SRS/FSR treatment characteristics, post-treatment CNNs recovery duration, status, and radiological control on their last follow-up. RESULTS: The median follow-up duration was 53.4 months. Patients were treated with SRS (n = 25) or FSR (n = 21). The mean pretreatment tumor volume was 9.5 cc decreasing to a mean end-of-follow-up tumor volume was 5.1 cc. Radiological tumor control was achieved in all cases. CNN recovery was observed in 80.4% of patients, with specific nerve recoveries documented as follows: extra-ocular nerves (43.2%), trigeminal nerve (32.4%), and optic nerve (10.8%). A higher CNNs recovery rate was associated with a smaller pre-treatment tumor volume (p < 0.001), and the median time-to-improvement was 3.7 months. Patients with tumor volumes exceeding 6.8 cc and those treated with FSR exhibited prolonged time-to-improvement (P < 0.03 and P < 0.04 respectively). CONCLUSIONS: This study suggests that SRS/FSR for CSM provides good and sustainable CNNs recovery outcomes with excellent long-term radiological control. A higher CNNs recovery rate was associated with a smaller pre-treatment tumor volume. while shorter time-to-improvement was identified in patients treated with SRS compared to FSR, particularly in those with small pre-treatment tumor volume.

Contralateral Transmaxillary Corridor Used in Endoscopic Endonasal Approach for Resecting Adenoma Invading the Retrocarotid Area of the Cavernous Sinus and Beyond: Surgical Anatomy, Patient Selection Algorithm, and Illustrative Cases.

BACKGROUND AND OBJECTIVES: The cavernous internal carotid artery (cICA) and its branches can make it challenging to approach the lateral portion of the retrocarotid area of the cavernous sinus (RcACS) and surrounding areas during the endoscopic endonasal approach (EEA). This can sometimes require more invasive transcranial approaches, causing a higher risk of complications. We sought to explore the feasibility of adding a contralateral transmaxillary (CTM) corridor to improve access to the RcACS during EEA. METHODS: We performed EEA and CTM extensions on 6 cadavers (12 sides) using image guidance. The depth of the surgical corridor, the surgical exposure, the angle of attack, and the trajectory to the anterior genu of the cICA were measured. Two illustrative clinical cases are presented. RESULTS: Compared with the contralateral transnasal approach, the CTM corridor provided a 10.76 (5.32)-mm shorter distance ( P < .001), 36.23% (20.70%) larger surgical exposure ( P < .001), and a 24.6° (3.4°) more parallel trajectory to the anterior genu of the cICA ( P < .001). The mean angle of the lateral nasal wall line and the middle eye line was equal to the mean angle of the contralateral transnasal ( P = .075) and CTM ( P = .262) approaches, respectively. The CTM corridor allowed us to achieve near-total resection of the RcACS and beyond in 2 invasive adenomas with significant lateral extension. CONCLUSION: The CTM corridor is a feasible addition to standard EEA to access the RcACS and beyond, providing a more medial-to-lateral trajectory and improved access. The middle eye line can be used as a reference to help select patients for this approach.

[Clinical observation of 7 cases of functional pituitary neuroendocrine tumor treated by endoscopic transnasal selective resection of the cavernous sinus medial wall].

The clinical data of 7 patients (3 males and 4 females) with functional pituitary neuroendocrine tumor treated by endoscopic transnasal resection of the cavernous sinus medial wall from May to October 2023 in the Department of Neurosurgery of the First Affiliated Hospital of University of Science and Technology of China were retrospectively analyzed. They ranged in age from 29 to 60, with an average age of 45. The clinical diagnosis was acromegaly in 5 cases and Cushing's disease in 2 cases. There were 1 cases of microadenoma and 6 cases of macroadenoma. Knosp grade: Grade 1 adenoma in 3 cases, grade 2 adenoma in 3 cases and grade 3A adenoma in 1 case. Intraoperative resection of cavernous sinus medial wall was performed on the side of tumor. Five cases were determined to be invaded by tumor, and 2 cases were uncertain. No internal carotid artery injury occurred in all patients. The average intraoperative blood loss was 156 ml, and no patient was transfused. Postoperative endocrine remission was found in 6 cases, and tumor cells were found in 6 cases by pathological examination of the medial wall of cavernous sinus. No serious complications occurred in all patients. For Knosp grade 1-3 functional pituitary neuroendocrine tumor surgery, if there is no clear false envelope or normal pituitary between the tumor and the cavernous sinus medial wall during the operation, the cavernous sinus medial wall should be actively removed to improve the postoperative endocrine remission rate.

Extended Long-Term Outcome After Conservative Decompressive Microsurgery and Routine Adjuvant Fractionated Stereotactic Radiotherapy for Symptomatic Cavernous Sinus Meningiomas.

BACKGROUND AND OBJECTIVES: Cavernous sinus meningiomas (CSM) pose one of the most difficult to treat subgroup of skull base meningiomas. The purpose of this study was to evaluate the efficacy of an interdisciplinary treatment approach for symptomatic CSM which incorporated conservative function preserving microsurgery and routine adjuvant fractionated stereotactic radiotherapy (FSRT). METHODS: A homogenous group of patients with symptomatic primary CSM with extracavernous extension was treated between 2005 and 2012. All patients were available for a minimum follow-up of 5 years. Clinical follow-up included detailed examination of oculomotor deficits, visual status, and endocrinologic function. Radiologic follow-up was conducted by tumor volumetry. RESULTS: Overall, 23 patients were included in this study (78.3% women; median age 58 years). Diplopia was the most common presenting symptom, followed by headache and visual disturbances. Surgical morbidity was low (3/23; 13%). FSRT was applied after a median of 2 months after surgery. At a median clinical follow-up of 113 months, 70.45% of the presenting symptoms had improved, 25% remained unchanged, and in 2 cases (4.54%), worsening occurred. Overall tumor regression was evident in 19/21 World Health Organization 1 and in 1/2 of World Health Organization 2 CSM, respectively, at a median radiological follow-up of 103 months. CONCLUSION: Our findings demonstrate the efficacy of an interdisciplinary treatment approach for symptomatic primary CSM with extracavernous extension with decompression of neurovascular elements followed by FSRT. Precise preoperative planning and intraoperative decision making in combination with routine postoperative radiotherapy can achieve excellent tumor control, improve neurologic function, and minimize long-term morbidity.

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.

Intradural anatomy and mobilization techniques of oculomotor, trochlear and abducens nerve after microsurgical dissection: a cadaveric study.

BACKGROUND: This study investigates the mobilization of cranial nerves in the upper clival region to improve surgical approaches. Cadaveric specimens (n = 20) were dissected to examine the oculomotor, trochlear, and abducens nerves. Dissection techniques focused on the nerves' intradural course and their relationship to surrounding structures. METHODS: Pre-dissection revealed the nerves' entry points into the clival dura and their proximity to each other. Measurements were taken to quantify these distances. Following intradural dissection, measurements were again obtained to assess the degree of nerve mobilization. RESULTS: Dissection showed that the abducens nerve takes three folds during its course: at the dural foramen, towards the posterior cavernous sinus, and lastly within the cavernous sinus. The trochlear nerve enters the dura and makes two bends before entering the cavernous sinus. The oculomotor nerve enters the cavernous sinus directly and runs parallel to the trochlear nerve. Importantly, intradural dissection increased the space between the abducens nerves (by 4.21 mm) and between the oculomotor and trochlear nerves (by 3.09 mm on average). This indicates that nerve mobilization can create wider surgical corridors for approaching lesions in the upper clivus region. CONCLUSIONS: This study provides a detailed anatomical analysis of the oculomotor, trochlear, and abducens nerves in the upper clivus. The cadaveric dissections and measurements demonstrate the feasibility of mobilizing these nerves to achieve wider surgical corridors. This information can be valuable for surgeons planning endoscopic or microscopic approaches to lesions in the upper clivus region.

Endoscopic transcavernous approach for functional pituitary adenomas.

BACKGROUND: Invasion of the CS is one of the limiting factors for total resection for PitNet tumors with cure rates less than 30%. Extended approaches may be considered in selective and well-studied cases of secreting adenomas. METHOD: We describe the key steps of the endoscopic transcavernous approach for functional pituitary adenomas with a video illustration. The surgical anatomy is described along with the advantages and limitations of this approach. CONCLUSION: A detailed knowledge of CS anatomy and familiarity with this surgical approach acquired in the laboratory is essential. Proper instrumentation is critical to decrease the risks of vascular injury.

Clinical and therapeutic implications of cavernous sinus invasion in pituitary adenomas.

Invasion of the cavernous sinus by pituitary adenomas impedes complete surgical resection, compromises biochemical remission, and increases the risk of further tumor recurrence. Accurate preoperative MRI-based diagnosis or intraoperative direct inspection of cavernous sinus invasion are essential for optimal surgical planning and for tailoring postoperative therapeutic strategies, depending on whether a total resection has been achieved, or tumoral tissue has been left in surgically inaccessible locations. The molecular mechanisms underlying the invasive behavior of pituitary adenomas remain poorly understood, hindering the development of targeted therapies. Some studies have identified genes overexpressed in pituitary adenomas invading the cavernous sinus, offering insights into the acquisition of invasive behavior. Their main limitation however lies in comparing purely intrasellar specimens obtained from invasive and non-invasive adenomas. Further, precise anatomical knowledge of the medial wall of the cavernous sinus is crucial for grasping the mechanisms of invasion. Recently, alongside the standard intrasellar surgery, extended endoscopic intracavernous surgical procedures with systematic selective resection of the medial wall of the cavernous sinus have shown promising results for invasive secreting pituitary adenomas. The first- and second-generation somatostatin agonist ligands and cabergoline are used with variable efficacy to control secretory activity and/or growth of intracavernous remnants. Tumor regrowth usually requires surgical reintervention, sometimes combined with radiotherapy or radiosurgery which is applied despite their benign nature. Unraveling the molecular pathways driving invasive behavior of pituitary adenomas and their tropism to the cavernous sinuses is the key for developing efficient innovative treatment modalities that could reduce the need for repeated surgery or radiotherapy.

Comparative analysis of intraoperative and imaging features of invasive growth in pituitary adenomas.

BACKGROUND: Most pituitary adenomas (PAs), also termed pituitary neuroendocrine tumors, are benign in nature and can be treated effectively by surgical resection, medical treatment, and in special cases by radiotherapy. However, invasive growth can be an important feature of a more aggressive behavior and adverse prognosis. The extension of PAs into the cavernous sinus can be categorized according to the Knosp criteria on magnetic resonance imaging (MRI). Comparative analyses of MRI features and intraoperative findings of invasive growth regarding different clinical factors are still scarce. MATERIALS AND METHODS: We performed a retrospective single-center analysis of 764 PAs that were surgically treated between October 2004 and April 2018. Invasive growth was assessed according to the surgical reports and preoperative MRI (Knosp criteria). Clinical data, such as patient age at diagnosis and gender, histopathological adenoma type, and extent of resection, were collected. RESULTS: Invasive features on MRI were seen in 24.4% (Knosp grades 3A-4, 186/764) of the cases. Intraoperatively, invasion was present in 42.4% (324/764). Complete resection was achieved in 80.0% of adenomas and subtotal resection, in 20.1%. By multivariate analysis, invasion according to intraoperative findings was associated with the sparsely granulated corticotroph (SGCA, P = .0026) and sparsely granulated somatotroph (SGSA, P = .0103) adenoma type as well as age (P = .0287). Radiographic invasion according to Knosp grades 3A-4 correlated with age (P = .0098), SGCAs (P = .0005), SGSAs (P = .0351), and gonadotroph adenomas (P = .0478). Both criteria of invasion correlated with subtotal resection (P = .0001, respectively). CONCLUSIONS: Both intraoperative and radiographic signs of invasive growth are high-risk lesions for incomplete extent of resection and occur more frequently in older patients. A particularly high prevalence of invasion can be found in the SGCA and SGSA types. Cavernous sinus invasion is also more common in gonadotroph adenomas. Usage of the Knosp classification is a valuable preoperative estimation tool.

Cavernous Sinus Thrombosis.

Cavernous sinus thrombosis is a potentially lethal subset of cerebral venous sinus thrombosis that may occur as a result of septic and aseptic etiologies. The overall incidence is estimated to be between 0.2 and 1.6 per 100,000 persons; and treatments include antibiotics, anticoagulation, corticosteroids, and surgery. Recent morbidity and mortality estimates are approximately 15% and 11%, respectively. Rapid identification and treatment are essential and may reduce the risk of poor outcome or death.

Carotid Cavernous Fistula.

Carotid cavernous fistulae (CCFs) are arteriovenous shunts involving the cavernous sinus. CCFs are defined as direct or indirect. Direct CCFs are treated by deconstructive or reconstructive techniques depending on whether the affected internal carotid artery is required to perfuse the ipsilateral cerebral hemisphere, as determined by a balloon test occlusion. Indirect CCFs, or dural fistulae of the cavernous sinus wall, are most often treated with transvenous embolization. Stereotactic radiosurgery is reserved for cases of indirect CCFs that are not completely obliterated by embolization. Overall, cure rates are high with relatively low complication rates.

A quantitative comparative surgical analysis of the endoscopic transorbital approach and frontotemporal-orbitozygomatic approach for extradural exposure of the cavernous sinus.

OBJECTIVE: Recently, the endoscopic superior eyelid transorbital approach (SETA) has emerged as a potential alternative to access the cavernous sinus (CS). Several previous studies have attempted to quantitatively compare the traditional open anterolateral skull base approaches with transorbital exposure; however, these comparisons have been limited to the area of exposure provided by the bone opening and trajectory, and fail to account for the main avenues of exposure provided by subsequent requisite surgical maneuvers. The authors quantitatively compare the surgical access provided by the frontotemporal-orbitozygomatic (FTOZ) approach and the SETA following applicable periclinoid surgical maneuvers, evaluate the surgical exposure of key structures in each, and discuss optimal approach selection. METHODS: SETA and FTOZ approaches were performed with subsequent applicable surgical maneuvers on 8 cadaveric heads. The lengths of exposure of cranial nerves (CNs) II-VI and the cavernous internal carotid artery; the areas of the space accessed within the supratrochlear, infratrochlear, and supramaxillary (anteromedial) triangles; the total area of exposure; and the angles of attack were measured and compared. RESULTS: Exposure of the extradural CS was comparable between approaches, whereas access was significantly greater in the FTOZ approach compared with the SETA. The lengths of extradural exposure of CN III, V1, V2, and V3 were comparable between approaches. The FTOZ approach provided marginally increased exposure of CNs IV (20.9 ± 2.36 mm vs 13.4 ± 3.97 mm, p = 0.023) and VI (14.1 ± 2.44 mm vs 9.22 ± 3.45 mm, p = 0.066). The FTOZ also provided significantly larger vertical (44.5° ± 6.15° vs 18.4° ± 1.65°, p = 0.002) and horizontal (41.5° ± 5.40° vs 15.3° ± 5.06°, p < 0.001) angles of attack, and thus significantly greater surgical freedom, and provided significantly greater access to the supratrochlear (p = 0.021) and infratrochlear (p = 0.007) triangles, and significantly greater exposure of the cavernous internal carotid artery (17.2 ± 1.70 mm vs 8.05 ± 2.37 mm, p = 0.001). Total area of exposure was also significantly larger in the FTOZ, which provided wide access to the lateral wall of the CS as well as the possibility for intradural access. CONCLUSIONS: This is the first study to quantitatively identify the relative advantages of the FTOZ and transorbital approaches at the target region following requisite surgical maneuvers. Understanding these data will aid in selecting an optimal approach and maneuver set based on target lesion size and location.

Transorbital neuroendoscopic surgery for treatment of sphenoid wing meningiomas extending to the cavernous sinus: clinical implications and a technical illustration.

OBJECTIVE: The aim of this study was to evaluate the efficacy and safety of transorbital neuroendoscopic surgery (TONES) in the management of sphenoid wing meningiomas (SWMs) with cavernous sinus and orbital invasion. METHODS: The authors conducted a retrospective review of 32 patients with SWMs treated at Gazi University using TONES from October 2019 to May 2023. The study includes clinical applications to elucidate the endoscopic transorbital approach. Surgical techniques focused on safe subtotal resection, aiming to minimize residual tumor volume for subsequent radiosurgery. Data were collected on patient demographics, tumor characteristics, surgical procedures, complications, and postoperative outcomes, including radiological imaging and ophthalmological evaluations. RESULTS: Surgical dissections delineated a three-phase endoscopic transorbital approach: extraorbital, intraorbital, and intracranial. In the clinical application, gross-total resection was not achieved in any patient because of planned postoperative Gamma Knife radiosurgery. The mean follow-up period was 16.3 months. Of 30 patients with preoperative proptosis, 25 experienced postoperative improvement. No new-onset extraocular muscle paresis or visual loss occurred postoperatively. The average hospital stay was 1.15 days, with minimal complications and no significant morbidity or mortality. CONCLUSIONS: Total resection of SWMs invading the cavernous sinus and orbit is associated with substantial risks, particularly cranial nerve deficits. TONES offers a minimally invasive alternative, reducing morbidity compared with transcranial approaches, and represents a significant advancement in the surgical management of SWMs, especially those extending into the cavernous sinus and orbit. The approach provides a safe, effective, and patient-centric approach, prioritizing subtotal resection to minimize neurological deficits while preparing patients for adjunctive radiosurgery. This study positions TONES as a transformative surgical technique, aligning therapeutic efficacy with neurovascular preservation and postoperative recovery.

Usefulness of Opening the Diaphragma Sellae Before Transecting Interclinoidal Ligament for Endoscopic Endonasal Transoculomotor Triangle Approach: Technical Nuances and Surgical Outcomes.

OBJECTIVE: Opening the oculomotor triangle (OT) and removing the posterior fossa lesion by endoscopic endonasal approach (EEA) is challenging for even an experienced endoscopic neurosurgeon. We summarize the treatment experience and technical nuances with EEA for resection of pituitary neuroendocrine tumors and cavernous sinus (CS) meningiomas invading through the OT. METHODS: Between 2018 and 2022, 8 patients, comprising 5 with pituitary neuroendocrine tumors (3 with nonfunctioning and 2 with somatotroph tumors with increased levels of growth hormone) and 3 CS meningiomas, were treated using an endoscopic endonasal transoculomotor triangle approach. The critical surgical technique is continuously opening the diaphragma sellae from medial to lateral toward the interclinoidal ligament and transecting it to enlarge the OT. We evaluated preoperative tumor size, previous surgical history, preoperative symptoms, extent of tumor resection, histopathology, and postoperative complications for all patients. RESULTS: The gross total resection (defined as complete removal) in 3 patients (38%), near-total resection (defined as >95% removal) in 4 patients (50%), and subtotal resection (defined as ≤90% removal) in 1 patient (12%) and gross total resection of tumor invading through the OT was achieved in all patients through pure EEA. Two of 3 patients with visual deficits in nonfunctioning pituitary neuroendocrine tumors improved, and the other remained stable postoperatively. One patient showed transient oculomotor nerve palsy. The growth hormone level of the 2 patients with somatotroph tumors declined to normal. For 3 patients with CS meningiomas, cranial nerve palsy improved in 2 patients, whereas the other patient developed increased facial numbness after surgery. CONCLUSIONS: The endoscopic endonasal transoculomotor triangle approach is an efficient surgical option for tumors with CS invasion and OT penetration.

Comparison of the transarterial, transvenous, and superior ophthalmic vein approaches in the treatment of indirect carotid-cavernous fistulas.

OBJECTIVE: Indirect carotid-cavernous fistulas (CCFs) are abnormal arteriovenous shunting lesions with a highly variable clinical presentation that depends on the drainage pattern. Based on venous drainage, treatment can be either transarterial (TA) or transvenous (TV). The aim of this study was to compare the outcomes of indirect CCF embolization via the TA, TV, and direct superior ophthalmic vein (SOV) approaches. METHODS: The authors conducted a retrospective analysis of 74 patients admitted to their institution from 2010 to 2023 with the diagnosis of 77 indirect CCFs as confirmed on digital subtraction angiography. RESULTS: A total of 74 patients with 77 indirect CCFs were included in this study. Embolization was performed via the TA approach in 4 cases, the TV approach in 50 cases, and the SOV in 23 cases. At the end of the procedure, complete occlusion was achieved in 76 (98.7%) cases. The rate of complete occlusion at the end of the procedure and at last radiological follow-up was significantly higher in the SOV and TV cohorts than in the TA cohort. The rate of recurrence was highest in the TA cohort (25% for TA vs 5.3% for TV vs 0% for SOV, p = 0.68). CONCLUSIONS: The rate of immediate complete occlusion was higher in the TV and SOV cohorts than in the TA cohort while the rate of complete occlusion at final follow-up was highest in the SOV cohort. The SOV approach was significantly associated with higher rates of postoperative complications. Indirect CCFs require careful examination of the fistulous point and the venous drainage to provide the most effective patient-tailored approach.

Further investigation of the lateral approach for the resection of Knosp grade 4 pituitary adenomas in endoscopic endonasal surgery.

OBJECTIVE: The authors performed a further in-depth study of the lateral compartment of the cavernous sinus (LCCS) by the endoscopic endonasal approach to improve the safety and efficacy of the lateral approach for the removal of Knosp grade 4 pituitary adenomas (KG4PAs). METHODS: Twenty-three cadaveric specimens were used for endoscopic endonasal dissection, and the LCCS was exposed to observe the neurovascular and fibrous structures within. A subclassification of the lateral approach based on further knowledge of the LCCS was proposed and used to resect 86 KG4PAs, and the surgical outcomes of these cases were reviewed. Type A KG4PAs represent tumor that was mainly distributed in the posterosuperior and superolateral compartments, type B KG4PAs represent tumor that was mainly distributed in the anteroinferior compartments, and type AB KG4PAs represent tumor that extended into each compartment with characteristics of types 4A and 4B. RESULTS: The authors identified multiple fibers that anchored the horizontal segment of the internal carotid artery (ICA) to the abducens nerve. The fibers, the sympathetic nerve, and the inferior lateral trunk form a partition-like structure in the LCCS named the abducens nerve-ICA complex (AIC), and the LCCS can be divided into the superolateral and inferolateral compartments by the AIC. Accordingly, the lateral approach was subclassified into the lateral superior (LS) approach and the anterior inferior (AI) approach. The LS approach was mainly used to resect type A KG4PAs, whereas the AI approach was used to resect type B KG4PAs, and a combination of the two was used to resect type AB KG4PAs. The gross-total, subtotal, and partial resection rates were 81.4%, 12.8%, and 5.8%, respectively. The numbers of cases of postoperative transient cranial nerve palsy, postoperative permanent cranial nerve palsy, ICA injury, and CSF leakage were 6 (6.9%), 2 (2.3%), 1 (1.2%), and 1 (1.2%), respectively. CONCLUSIONS: This study revealed that the LCCS is divided by the AIC into the superolateral and inferolateral compartments, avoiding the misconception that the LCCS has vertical communication. Therefore, the lateral approach was subclassified into the LS approach and the AI approach for the resection of KG4PAs, which allowed a high gross-total resection rate with acceptable safety in the surgical treatment of KG4PAs.

Endoscopic Endonasal Transsphenoidal Transcavernous Transoculomotor Triangle Approach for Resection of an Invasive Pituitary Adenoma Extending Into the Parapeduncular Space Through the Cavernous Sinus.

BACKGROUND AND IMPORTANCE: A subset of invasive pituitary adenomas invade not only the medial wall of the cavernous sinus but can progress superiorly through the cavernous sinus roof at the oculomotor triangle and reach the subarachnoid parapeduncular space. We describe a series of 2 of 3 cases where an endoscopic endonasal approach was used to reach the parapeduncular space through the oculomotor triangle for tumor decompression. Images of the third case are presented. CLINICAL PRESENTATION: Case 1: We present a 2-dimensional surgical video of a recurrent corticotroph adenoma post gamma knife radiotherapy which was invading the left cavernous sinus and extending into the left parapeduncular space. Histopathological examination revealed densely granulated corticotrophin adenoma. The patient had reduction in the serum cortisol level postoperatively and was induced into remission medically. Postoperative third nerve palsy recovered partially, and sixth nerve palsy recovered completely at the 3-month follow-up. Case 2 : A case of recurrent silent corticotrophin adenoma invading the right parapeduncular space through the right cavernous sinus was operated through the same approach as case 1. Only a subtotal excision of the tumor in the cisternal space was possible. The patient developed a complete right third cranial palsy in the immediate postoperative period with near total recovery at the 6-month follow-up. CONCLUSION: Endoscopic endonasal approach to the parapeduncular space through a transcavernous transoculomotor route is reasonably safe and effective, as long as key anatomic landmarks and structures are identified and preserved while using natural tumor corridors to achieve tumor clearance.

Successful surgical treatment of oculomotor palsy due to schwannoma of the cavernous sinus in a 7-year-old girl: a case report.

Oculomotor nerve schwannoma in children not associated with neurofibromatosis is a rare disease, with 26 pediatric cases reported so far. There is no established treatment plan. A 7-year-old girl presented with oculomotor nerve palsy. Surgical reduction of the tumor combined with postoperative gamma knife surgery preserved the oculomotor nerve, improved oculomotor nerve function, and achieved tumor control during the observation period of 20 months. The combination of partial surgical resection and gamma knife surgery as a treatment strategy for oculomotor nerve schwannoma resulted in a good outcome.