Management of large intraventricular meningiomas with minimally invasive port technique: a three-case series.

The use of minimally invasive transcranial ports for the resection of deep-seated lesions has been shown to be safe and effective. To date, most of the literature regarding the tubular retractors used in brain surgery is comprised of individual case reports that describe the successful resection of deep-seated lesions such as thalamic pilocytic astrocytomas, colloid cysts in the third ventricle, hematomas, and cavernous angiomas. The authors describe their experience using a tubular retractor system with three different cases involving large intraventricular meningiomas and examine radiographic and patient outcomes. A single-institution, retrospective case series was performed from a skull base database. Patients who underwent resection of intraventricular > 4-cm meningiomas with port technology were identified. The authors reviewed three cases to illustrate the feasibility of minimal access port surgery for the resection of these lesions. Complete resection was achieved in all cases. None of the patients developed permanent neurological deficits. There were no major complications related to surgery and no mortalities. Good clinical and surgical outcomes for atrium meningiomas can be achieved through the minimally invasive port technique and tumor size does not appear to be a limitation.

Improving Function in Cavernous Sinus Meningiomas: A Modern Treatment Algorithm.

Background: The efficacy and safety of radiosurgery led to paradigm shift in the management of cavernous sinus meningiomas. Nevertheless, patients are still significantly affected by cranial nerve deficits related to the mass effect of these tumors. Our management strategy involves the combination of a functional surgical decompression followed by radiation therapy. Methods: We reviewed a single institution's cohort of patients who underwent endoscopic endonasal decompression (EED) for symptomatic meningiomas primarily involving the cavernous sinus (CS) from 2010 to 2016. The preoperative neuro-ophthalmological exam was compared to the 1- and 6-month postoperative exams. The patient's length of hospital stay, complications, and radiological and clinical follow-up were noted. Results: A total of 17 patients underwent EED for CS meningiomas that fit our radiological criteria. The final outcome at the 6-month visit showed five patients (62.5%) with normalization of deficit and three patients (37.5%) with partial improvement of the CNII deficit. Out of the 12 patients who had cavernous sinus cranial nerves (CSCN) deficits, the final outcome at the 6-month visit showed four patients (33.33%) with normalization of deficit, seven patients (58.3%) with partial improvement, and one patient (8.33%) with no improvement. There were no intraoperative complications. Conclusion: The EED for CS meningiomas is a valuable technique when addressing acute/subacute CNII and CSCN deficits. This conservative surgical approach showed good functional outcomes, low morbidity, and low complication rates. However, it does not exempt the need for radiosurgery/radiation therapy for control of tumor growth.

Anatomical nuances of the internal carotid artery in relation to the quadrangular space.

OBJECTIVE The aim of this study was to evaluate the anatomical variations of the internal carotid artery (ICA) in relation to the quadrangular space (QS) and to propose a classification system based on the results. METHODS A total of 44 human cadaveric specimens were dissected endonasally under direct endoscopic visualization. During the dissection, the anatomical variations of the ICA and their relationship with the QS were noted. RESULTS The space between the paraclival ICAs (i.e., intercarotid space) can be classified as 1 of 3 different shapes (i.e., trapezoid, square, or hourglass) based on the trajectory of the ICAs. The ICA trajectories also directly influence the volumetric area of the QS. Based on its geometry, the QS was classified as one of the following: 1) Type A has the smallest QS area and is associated with a trapezoid intercarotid space, 2) Type B corresponds to the expected QS area (not minimized or enlarged) and is associated with a square intercarotid space, and 3) Type C has the largest QS area and is associated with an hourglass intercarotid space. CONCLUSIONS The different trajectories of the ICAs can modify the area of the QS and may be an essential parameter to consider for preoperative planning and defining the most appropriate corridor to reach Meckel's cave. In addition, ICA trajectories should be considered prior to surgery to avoid injuring the vessels.

Newly Diagnosed Sellar Tumors in Patients with Cancer: A Diagnostic Challenge and Management Dilemma.

BACKGROUND: The use of combined positron emission tomography/computed tomography for staging in patients with cancer and the widespread use of magnetic resonance imaging has led to increased detection of incidental sellar masses. The imaging findings can be suggestive of a benign pituitary tumor, but metastasis can never be completely ruled out with noninvasive work-up. Appropriate diagnosis of sellar masses is critical, as the treatment paradigm might change in the presence of a pituitary metastasis. Definitive tissue diagnosis might prevent unnecessary radiotherapy to the skull base or the need for systemic treatment when benign pituitary disease is confirmed. METHODS: A retrospective chart review from 2010 to 2015 of all patients with recently diagnosed cancer and undergoing surgery for sellar region masses was performed. RESULTS: There were 9 patients (3 female and 6 male) identified. Lung cancer was the primary condition in 4 patients; the remaining 5 patients had breast cancer, follicular thyroid cancer, cutaneous melanoma, colorectal carcinoma, and renal cell carcinoma. On final pathology, the sellar mass was a benign pituitary adenoma in 5 patients, metastatic cancer in 3 patients, and a granular cell tumor in 1 patient. CONCLUSIONS: Surgical resection of a sellar mass in patients with known cancer helps in the definitive diagnosis, relieves compressive symptoms, and avoids unnecessary empiric radiotherapy in cases of confirmed benign pituitary disease.

Optic Canal Decompression: Comparison of 2 Surgical Techniques.

BACKGROUND: The optic canal is a bony channel that connects the anterior cranial fossa and orbit and contains the optic nerve and ophthalmic artery. It can be affected by several pathologies, leading to compression of the nerve nearby or inside the canal, leading to visual impairment. The usual technique to decompress the canal is through a craniotomy, but recently endoscopic endonasal approaches (EEAs) have surfaced as an interesting alternative due to direct access to the canal without the need for manipulation of neurovascular structures. METHODS: Six specimens were dissected. The right optic canal was drilled on the right side via the EEA, and the left optic canal was drilled via frontotemporal craniotomy. The amount of decompression was measured using a 3-dimensional reconstruction on computed tomography scans and compared. RESULTS: The EEA generated an average of 267.8 (221-294) degrees of decompression in the anterior portion of the canal versus 258.3 (219-300) degrees of decompression in the posterior portion of the canal, whereas the craniotomy generated an average of 229.3 (101-289) degrees of decompression in the anterior portion of the canal versus 250.3 (76-300) degrees of decompression in the posterior portion of the canal. There was no significant difference statistically. CONCLUSION: The decision for an approach for optic canal decompression should be based on the site of the pathology and localization of canal involvement. Both techniques are equivalent in terms of proportion of nerve decompression.

Role of Leukocyte-Platelet-Rich Fibrin in Endoscopic Endonasal Skull Base Surgery Defect Reconstruction.

Objective Advancements in endoscopic endonasal approaches have increased the extent and complexity of skull base resections, in turn demanding the development of novel techniques for skull base defect reconstruction. The objective of this pilot study was to investigate the effect of leukocyte-platelet-rich fibrin (L-PRF) on the postoperative healing after endoscopic skull base surgery. Methods Between January and May of 2015, 47 patients underwent endoscopic endonasal resection of sellar, parasellar, and suprasellar lesions with the application of L-PRF membranes during the skull base reconstruction at two surgical centers. Early postoperative records were retrospectively reviewed. Results We found that 21 days following the surgery, 17/41 patients (42%) demonstrated improvement in the crusting score as compared with their 7 day postoperative examination. Ten of these patients (23%) showed no crusting. Fourteen (34%) patients had no change in the crusting score. Six patient records were incomplete. A total of 4/47 cases (8.5%) had postoperative cerebrospinal fluid leak requiring surgical repair. Conclusion This study demonstrates the potential utility of L-PRF membranes for skull base defect reconstruction. Future studies will be conducted to better assess the role of L-PRF in endoscopic skull base surgery.

Effect of Incremental Endoscopic Maxillectomy on Surgical Exposure of the Pterygopalatine and Infratemporal Fossae.

Objective Access to the pterygopalatine and infratemporal fossae presents a significant surgical challenge, owing to their deep-seated location and complex neurovascular anatomy. This study elucidates the benefits of incremental medial maxillectomies to access this region. We compared access to the medial aspect of the infratemporal fossa provided by medial maxillectomy, anteriorly extended medial maxillectomy, endoscopic Denker approach (i.e., Sturmann-Canfield approach), contralateral transseptal approach, and the sublabial anterior maxillotomy (SAM). Methods We studied 10 cadaveric specimens (20 sides) dissecting the pterygopalatine and infratemporal fossae bilaterally. Radius of access was calculated using a navigation probe aligned with the endoscopic line of sight. Area of exposure was calculated as the area removed from the posterior wall of maxillary sinus. Surgical freedom was calculated by computing the working area at the proximal end of the instrument with the distal end fixed at a target. Results The endoscopic Denker approach offered a superior area of exposure (8.46 ± 1.56 cm(2)) and superior surgical freedom. Degree of lateral access with the SAM approach was similar to that of the Denker. Conclusion Our study suggests that an anterior extension of the medial maxillectomy or a cross-court approach increases both the area of exposure and surgical freedom. Further increases can be seen upon progression to a Denker approach.

Comparative analysis of the anterior transpetrosal approach with the endoscopic endonasal approach to the petroclival region.

OBJECTIVE The endoscopic endonasal approach (EEA) offers direct access to midline skull base lesions, and the anterior transpetrosal approach (ATPA) stands out as a method for granting entry into the upper and middle clival areas. This study evaluated the feasibility of performing EEA for tumors located in the petroclival region in comparison with ATPA. METHODS On 8 embalmed cadaver heads, EEA to the petroclival region was performed utilizing a 4-mm endoscope with either 0° or 30° lenses, and an ATPA was performed under microscopic visualization. A comparison was executed based on measurements of 5 heads (10 sides). Case illustrations were utilized to demonstrate the advantages and disadvantages of EEA and ATPA when dealing with petroclival conditions. RESULTS Extradurally, EEA allows direct access to the medial petrous apex, which is limited by the petrous and paraclival internal carotid artery (ICA) segments laterally. The ATPA offers direct access to the petrous apex, which is blocked by the petrous ICA and abducens nerve inferiorly. Intradurally, the EEA allows a direct view of the areas medial to the cisternal segment of cranial nerve VI with limited lateral exposure. ATPA offers excellent access to the cistern between cranial nerves III and VIII. The quantitative analysis demonstrated that the EEA corridor could be expanded laterally with an angled drill up to 1.8 times wider than the bone window between both paraclival ICA segments. CONCLUSIONS The midline, horizontal line of the petrous ICA segment, paraclival ICA segment, and the abducens nerve are the main landmarks used to decide which approach to the petroclival region to select. The EEA is superior to the ATPA for accessing lesions medial or caudal to the abducens nerve, such as chordomas, chondrosarcomas, and midclival meningiomas. The ATPA is superior to lesions located posterior and/or lateral to the paraclival ICA segment and lesions with extension to the middle fossa and/or infratemporal fossa. The EEA and ATPA are complementary and can be used independently or in combination with each other in order to approach complex petroclival lesions.

Endoscopic endonasal study of the cavernous sinus and quadrangular space: Anatomic relationships.

BACKGROUND: The quadrangular space permits an anterior entry into Meckel's cave while obviating the need for cerebral or cranial nerve retraction. This avenue is intimately associated with the cavernous sinus; thus, from this ventral perspective, it is feasible to visualize the anteromedial, anterolateral, and Parkinson triangles. METHODS: Twenty middle cranial fossae were dissected endonasally under direct endoscopic visualization. Measurements of the surface area of the quadrangular space and the ventrally accessible cavernous sinus triangles were performed using 3 coordinates under image-guided navigation. RESULTS: The surface area of the quadrangular space was 16.36 mm(2) (±2.89 mm(2) ). The anterolateral triangle was the largest (47.27 ± 5.37 mm(2) ), whereas Parkinson's was the smallest (22.46 ± 5.54 mm(2) ); the anteromedial triangle presented an average surface area 36.07 mm(2) (±4.15 mm(2) ). CONCLUSION: The trajectory of the internal carotid artery (ICA) significantly impacts the quadrangular space area and may be a potential parameter for defining the feasibility of this corridor. © 2016 Wiley Periodicals, Inc. Head Neck 38: E1680-E1687, 2016.

Magnetic resonance imaging fluid-attenuated inversion recovery sequence signal reduction after endoscopic endonasal transcribiform total resection of olfactory groove meningiomas.

BACKGROUND: Olfactory groove meningiomas grow insidiously and compress adjacent cerebral structures. Achieving complete removal without further damage to frontal lobes can be difficult. Microsurgical removal of large lesions is a challenging procedure and usually involves some brain retraction. The endoscopic endonasal approaches (EEAs) for tumors arising from the anterior fossa have been well described; however, their effect on the adjacent brain tissue has not. Herein, the authors utilized the magnetic resonance imaging fluid attenuated inversion recovery (FLAIR) sequence signal as a marker for edema and gliosis on pre- and post-operative images of olfactory groove meningiomas, thus presenting an objective parameter for brain injury after surgical manipulation. METHODS: Imaging of 18 olfactory groove meningiomas removed through EEAs was reviewed. Tumor and pre/postoperative FLAIR signal volumes were assessed utilizing the DICOM image viewer OsiriX(®). Inclusion criteria were: (1) No previous treatment; (2) EEA gross total removal; (3) no further treatment. RESULTS: There were 14 females and 4 males; the average age was 53.8 years (±8.85 years). Average tumor volume was 24.75 cm(3) (±23.26 cm(3), range 2.8-75.7 cm(3)), average preoperative FLAIR volume 31.17 cm(3) (±39.38 cm(3), range 0-127.5 cm(3)) and average postoperative change volume, 4.16 cm(3) (±6.18 cm(3), range 0-22.2 cm(3)). Average time of postoperative scanning was 6 months (range 0.14-20 months). In all cases (100%) gross total tumor removal was achieved. Nine patients (50%) had no postoperative FLAIR changes. In 2 patients (9%) there was minimal increase of changes postoperatively (2.2 cm(3) and 6 cm(3) respectively); all others demonstrated image improvement. The most common complication was postoperative cerebrospinal fluid leakage (27.8%); 1 patient (5.5%) died due to systemic complications and pulmonary sepsis. CONCLUSIONS: FLAIR signal changes tend to resolve after endonasal tumor resection and do not seem to worsen with this operative technique.

Endoscopic Endonasal Approach for Removal of Tuberculum Sellae Meningiomas.

Tuberculum sellae meningiomas are challenging lesions; their critical location and often insidious growth rate enables significant distortion of the superjacent optic apparatus before the patient notices any visual impairment. This article describes the technical nuances, selection criteria and complication avoidance strategies for the endonasal resection of tuberculum sellae meningiomas. A stepwise description of the surgical technique is presented; indications, adjuvant technologies, pitfalls and the relevant anatomy are also reviewed. Tuberculum sellae meningiomas may be safely and effectively resected through the endonasal route; invasion of the optic canals does not represent a limitation.

The Endoscopic Endonasal Approach for Removal of Petroclival Chondrosarcomas.

Chondrosarcomas of the skull base are rare, locally invasive tumors that typically arise in the petroclival region, from degenerated chondroid cells located within the synchondrosis. Given their usually slow growth rate, they are capable of reaching sizable dimensions, promoting bone erosion and significant displacement of neurovascular structures before causing symptomatology that will eventually lead to diagnosis; cranial neuropathies and headaches are common complaints. This article discusses the pertinent surgical anatomy, patient selection criteria, technical nuances and complication management of the endonasal resection of skull base chondrosarcomas.

Contemporary management of clival chordomas.

PURPOSE OF REVIEW: Clival chordomas are rare malignant tumors associated with a poor prognosis. In this article, we review the current literature to identify a variety of strategies that provide guidelines toward the optimal management for this aggressive tumor. RECENT FINDINGS: Molecular disease, particularly, the development of characterized chordoma cell lines, has become one of the new cornerstones for the histological diagnosis of chordomas and for the development of effective chemotherapeutic agents against this tumor. Brachyury, a transcription factor in notochord development, seems to provide an excellent diagnostic marker for chordoma and may also prove to be a valuable target for chordoma therapy. Aggressive cytoreductive surgery aiming for gross total resection with maintenance of key neurovascular structures, followed by proton beam or hadron radiation, provides the best local recurrence and overall survival rates. SUMMARY: Clival chordomas are locally aggressive tumors that are challenging to treat because of their unique biology, proximity to key neurovascular structures and poor prognosis. Currently, chordomas are optimally managed with aggressive surgery, whilst preserving key structures, and postoperative radiation in a multidisciplinary setting with an experienced team. The advancement of molecular techniques offers exciting future diagnostic and therapeutic options in the management of chordomas.

Endoscopic endonasal cranial base surgery simulation using an artificial cranial base model created by selective laser sintering.

Mastery of the expanded endoscopic endonasal approach (EEA) requires anatomical knowledge and surgical skills; the learning curve for this technique is steep. To a great degree, these skills can be gained by cadaveric dissections; however, ethical, religious, and legal considerations may interfere with this paradigm in different regions of the world. We assessed an artificial cranial base model for the surgical simulation of EEA and compared its usefulness with that of cadaveric specimens. The model is made of both polyamide nylon and glass beads using a selective laser sintering (SLS) technique to reflect CT-DICOM data of the patient's head. It features several artificial cranial base structures such as the dura mater, venous sinuses, cavernous sinuses, internal carotid arteries, and cranial nerves. Under endoscopic view, the model was dissected through the nostrils using a high-speed drill and other endonasal surgical instruments. Anatomical structures around and inside the sphenoid sinus were accurately reconstructed in the model, and several important surgical landmarks, including the medial and lateral optico-carotid recesses and vidian canals, were observed. The bone was removed with a high-speed drill until it was eggshell thin and the dura mater was preserved, a technique very similar to that applied in patients during endonasal cranial base approaches. The model allowed simulation of almost all sagittal and coronal plane EEA modules. SLS modeling is a useful tool for acquiring the anatomical knowledge and surgical expertise for performing EEA while avoiding the ethical, religious, and infection-related problems inherent with use of cadaveric specimens.

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.

Advantages and limitations of endoscopic endonasal approaches to the skull base.

BACKGROUND: The anatomy of the skull base is extremely complex with an abundance of critical neurovascular bundles and their corresponding foramina as well as the insertions and origins of multiple masticatory and craniocervical muscles. These anatomic intricacies increase the difficulty of surgery within this area. METHODS: Advantages and disadvantages of endoscopic endonasal approaches (EEAs) based on the authors' sequential learning and experience are described. RESULTS: EEAs offer the advantages of using preexistent air spaces that enable accessing various areas of the skull base, while avoiding external incisions or scars and obviating the need for the translocation of the maxillofacial skeleton. In addition, EEAs are well suited to preserve neurologic, visual, and masticatory functions as well as cosmesis. However, the sinonasal corridor must be expanded and optimized to access the skull base adequately, facilitate the reconstruction of the surgical defect, avoid sinonasal complications, and minimize sequelae. Important considerations can limit or indicate the approach, such as the nature of the pathology, including location, diagnosis, and vascularity; patient characteristics, including age and medical comorbidities; surgeon attributes, including training, experience, and expertise; the resultant need to reconstruct large skull base defects and feasible alternatives to do so; and institutional resources, including adjunctive services, an intensive care unit, and operating room equipment. CONCLUSIONS: EEAs are important techniques in contemporary skull base surgery. Understanding the indications for and limitations of these approaches help to maximize outcomes.

Endonasal endoscopic approaches to the paramedian skull base.

OBJECTIVE: To describe the technical and anatomic nuances related to endoscopic endonasal approaches (EEAs) to the paramedian skull base. METHODS: Surgical indications, limitations, and technical aspects pertaining to EEAs designed to access areas oriented in the coronal plane are systematically reviewed with special attention to caveats, pitfalls, and common complications and how to avoid them. Case examples are presented. RESULTS: The paramedian skull base may be divided into anterior (corresponding to the orbit and its contents), middle (corresponding to the middle cranial, pterygopalatine, and infratemporal fossae), and posterior (includes the craniovertebral junction lateral to the occipital condyles and the jugular foramen) segments. EEAs to the anterior segment offer access to the intraconal orbital space and the optic canal. A transpterygoid corridor typically precedes EEAs to the middle and posterior paramedian approaches. EEAs to the middle segment provide wide exposure of the petrous apex, middle cranial fossa (including cavernous sinus and Meckel cave), and infratemporal and pterygopalatine fossae. Finally, EEAs to the posterior segment access the hypoglossal canal, occipital condyle, and jugular foramen. CONCLUSIONS: Approaches to the paramedian skull base are the most challenging and complex of all endoscopic endonasal techniques. Because of their technical complexity, it is recommended that surgeons master endoscopic endonasal anatomic approaches oriented to median structures (sagittal plane) before approaching paramedian (coronal plane) pathologies.

Clinical correlates of the anatomical relationships of the foramen ovale: a radioanatomical study.

Introduction Endonasal endoscopic transpterygoid approaches are commonly used techniques to access the infratemporal fossa and parapharyngeal space. Important endoscopic endonasal landmarks for the poststyloid parapharyngeal space, hence the internal carotid artery, include the mandibular nerve at the level of foramen ovale and the lateral pterygoid plate. This study aims to define the anatomical relationships of the foramen ovale, establishing its distance to other important anatomical landmarks such as the pterygoid process and columella. Methods Distances between the foramen ovale, foramen rotundum, and fixed anatomical landmarks like the columella and pterygoid process were measured using computed tomography (CT) scans and cadaveric dissections of the pterygopalatine and infratemporal fossae. Results The mean distances from the foramen ovale to columella and from the foramen rotundum to columella were found to be 9.15 cm and 7.09 cm, respectively. Analysis of radiologic measurements detected no statistically significant differences between sides or gender. Conclusions The pterygoid plates and V3 are prominent landmarks of the endonasal endoscopic approach to the infratemporal fossa and poststyloid parapharyngeal space. A better understanding of the endoscopic anatomy of the infratemporal fossa and awareness of the approximate distances and geometry among anatomical landmarks facilitates a safe and complete resection of lesions arising or extending to these regions.

Anatomic comparison of the endonasal and transpetrosal approaches for interpeduncular fossa access.

OBJECT: The interpeduncular cistern, including the retrochiasmatic area, is one of the most challenging regions to approach surgically. Various conventional approaches to this region have been described; however, only the endoscopic endonasal approach via the dorsum sellae and the transpetrosal approach provide ideal exposure with a caudal-cranial view. The authors compared these 2 approaches to clarify their limitations and intrinsic advantages for access to the interpeduncular cistern. METHODS: Four fresh cadaver heads were studied. An endoscopic endonasal approach via the dorsum sellae with pituitary transposition was performed to expose the interpeduncular cistern. A transpetrosal approach was performed bilaterally, combining a retrolabyrinthine presigmoid and a subtemporal transtentorium approach. Water balloons were used to simulate space-occupying lesions. "Water balloon tumors" (WBTs), inflated to 2 different volumes (0.5 and 1.0 ml), were placed in the interpeduncular cistern to compare visualization using the 2 approaches. The distances between cranial nerve (CN) III and the posterior communicating artery (PCoA) and between CN III and the edge of the tentorium were measured through a transpetrosal approach to determine the width of surgical corridors using 0- to 6-ml WBTs in the interpeduncular cistern (n = 8). RESULTS: Both approaches provided adequate exposure of the interpeduncular cistern. The endoscopic endonasal approach yielded a good visualization of both CN III and the PCoA when a WBT was in the interpeduncular cistern. Visualization of the contralateral anatomical structures was impaired in the transpetrosal approach. The surgical corridor to the interpeduncular cistern via the transpetrosal approach was narrow when the WBT volume was small, but its width increased as the WBT volume increased. There was a statistically significant increase in the maximum distance between CN III and the PCoA (p = 0.047) and between CN III and the tentorium (p = 0.029) when the WBT volume was 6 ml. CONCLUSIONS: Both approaches are valid surgical options for retrochiasmatic lesions such as craniopharyngiomas. The endoscopic endonasal approach via the dorsum sellae provides a direct and wide exposure of the interpeduncular cistern with negligible neurovascular manipulation. The transpetrosal approach also allows direct access to the interpeduncular cistern without pituitary manipulation; however, the surgical corridor is narrow due to the surrounding neurovascular structures and affords poor contralateral visibility. Conversely, in the presence of large or giant tumors in the interpeduncular cistern, which widen the spaces between neurovascular structures, the transpetrosal approach becomes a superior route, whereas the endoscopic endonasal approach may provide limited freedom of movement in the lateral extension.

Endoscopic endonasal surgical management of chondrosarcomas with cerebellopontine angle extension.

OBJECT: Skull base chondrosarcomas are slow-growing, locally invasive tumors that arise from the petroclival synchondrosis. These characteristics allow them to erode the clivus and petrous bone and slowly compress the contents of the posterior fossa progressively until the patient becomes symptomatic, typically from cranial neuropathies. Given the site of their genesis, surrounded by the petrous apex and the clival recess, these tumors can project to the middle fossa, cervical area, and posteriorly, toward the cerebellopontine angle (CPA). Expanded endoscopic endonasal approaches are versatile techniques that grant access to the petroclival synchondrosis, the core of these lesions. The ability to access multiple compartments, remove infiltrated bone, and achieve tumor resection without the need for neural retraction makes these techniques particularly appealing in the management of these complex lesions. METHODS: Analysis of the authors' database yielded 19 cases of skull base chondrosarcomas; among these were 5 cases with predominant CPA involvement. The electronic medical records of the 5 patients were retrospectively reviewed for age, sex, presentation, pre- and postoperative imaging, surgical technique, pathology, and follow-up. These cases were used to illustrate the surgical nuances involved in the endonasal resection of CPA chondrosarcomas. RESULTS: The male/female ratio was 1:4, and the patients' mean age was 55.2 ±11.2 years. All cases involved petrous bone and apex, with variable extensions to the posterior fossa and parapharyngeal space. The main clinical scenario was cranial nerve (CN) palsy, evidenced by diplopia (20%), ptosis (20%), CN VI palsy (20%), dysphagia (40%), impaired phonation (40%), hearing loss (20%), tinnitus (20%), and vertigo/dizziness (40%). Gross-total resection of the CPA component of the tumor was achieved in 4 cases (80%); near-total resection of the CPA component was performed in 1 case (20%). Two patients (40%) harbored high-grade chondrosarcomas. No patient experienced worsening neurological symptoms postoperatively. In 2 cases (40%), the symptoms were completely normalized after surgery. CONCLUSIONS: Expanded endoscopic endonasal approaches appear to be safe and effective in the resection of select skull base chondrosarcomas; those with predominant CPA involvement seem particularly amenable to resection through this technique. Further studies with larger cohorts are necessary to test these preliminary impressions and to compare their effectiveness with the results obtained with open approaches.