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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.

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.

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.

Objectives The pedicled nasoseptal flap (NSF) has dramatically reduced postoperative cerebrospinal fluid leakage following endoscopic endonasal approach (EEA) surgery. Although rare, its arterial supply may be damaged during harvest or may be preoperatively damaged for numerous reasons. Early recognition permits harvesting a contralateral flap before sacrificing its pedicle as part of the surgical exposure or use of an alternative flap. Design Technical feasibility study and case series. Setting Tertiary care university-associated medical center. Participants Five patients requiring an EEA with NSF reconstruction. Main Outcome Measures During NSF harvest, intravenous indocyanine green (IVICG) was administered, and a customized endoscopic system was used to visualize the emerging fluorescence. At the end of each case, just before final positioning of the NSF, additional IVICG was administered, and the custom endoscope was again introduced to evaluate fluorescence. Results In four patients, the entire NSF fluoresced brightly with IVICG on initial harvest and before final positioning. One patient showed heterogeneous fluorescence of the pedicle and distal parts of the NSF at both stages. All NSFs healed well without complication. Conclusion IVICG facilitates real-time evaluation NSF's arterial supply. This may provide early recognition of arterial compromise, allowing the harvest of alternate flaps or modification of surgery.

Objectives The purpose of this study is to demonstrate the potential contribution of positron emission tomography (PET)/computed tomography (CT) to help differentiate olfactory neuroblastoma (ONB) from sinonasal undifferentiated carcinoma (SNUC). Methods Following approval by the institutional review board at the Wexner Medical Center at the Ohio State University, Columbus, Ohio, a pilot study with retrospective review of patients with biopsy-proven diagnosis of ONB s and SNUC s was conducted. Staging PET/CT scans were reviewed to document the maximum standardized uptake value (SUVmax). A statistical comparison of SUVmax was performed. Results We identified 13 patients (7 with ONBs and 6 with SNUCs) with mean age 60.2 years who had undergone staging F-18 fluorodeoxyglucose (18F-FDG) PET/CT of the primary tumor at the time of their diagnosis. Mean SUVmax was found to be five-fold higher in SNUC patients (35.63, range 10.8–77.9) than in ONB patients (7.24, range 4.6–10.7) (P ≤ 0.00169). Conclusion Maximum standardized uptake value of 18F-FDG PET/CT can be used to initially discriminate between ONB and SNUC. This finding may prove helpful to guide diagnostic and treatment planning when the histopathologic diagnosis is inconclusive. Level of Evidence 4. Laryngoscope, 2016

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.

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.

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.

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 Laryngoscope, 125:1284–1290, 2015

OBJECTIVEThe 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.METHODSA 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.RESULTSThe 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.CONCLUSIONSThe 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.

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.

Introduction Malignancies of the clivus and petroclival region are mainly chordomas and chondrosarcomas. Although a spectrum of malignancies may present in this area, a finite group of commonly encountered malignant pathologies will be the focus of this review, as they are recognized to be formidable pathologies due to adjacent critical neurovascular structures and challenging surgical approaches. Objectives The objective is to review the literature regarding medical and surgical management of malignant tumors of the clival and petroclival region with a focus on clinical presentation, diagnostic identification, and associated adjuvant therapies. We will also discuss our current treatment paradigm using endoscopic, open, and combined approaches to the skull base. Data Synthesis A literature review was conducted, searching for basic science and clinical evidence from PubMed, Medline, and the Cochrane Database. The selection criteria encompassed original articles including data from both basic science and clinical literature, case series, case reports, and review articles on the etiology, diagnosis, treatment, and management of skull base malignancies in the clival and petroclival region. Conclusions The management of petroclival malignancies requires a multidisciplinary team to deliver the most complete surgical resection, with minimal morbidity, followed by appropriate adjuvant therapy. We advocate the combination of endoscopic and open approaches (traditional or minimally invasive) as required by the particular tumor followed by radiation therapy to optimize oncologic outcomes.

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.

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.

Throughout the last decade, the use of endoscopic skull base surgery has increased, aggregating the efforts of otolaryngologists-head and neck surgeons, and neurosurgeons. Using the natural sinonasal corridor to reach virtually the entire ventral skull base, this aspect of skull base surgery has grown exponentially, adding anatomy-based modular techniques that enable the safe removal of complex neoplasms, even in the presence of intradural progression or vascular encasement. Nonetheless, the safe employment of this technique requires fastidious planning, meticulous intraoperative management and thorough postoperative care to yield optimal results and prevent complications. Patients are preoperatively submitted to a clinical evaluation and a series of complementary imaging studies in order to warrant proper selection of the technique. During surgery, appropriate training and adequate resources, coupled with skilled anesthesiology support, allow the surgical team to safely perform the transnasal approach, dissection and resection of the tumor and reconstruction of the resultant defect. The postoperative period is equally important and aims not only to facilitate a speedy recovery, but also to prevent potential complications. This study describes those measures in the planning and perioperative management of skull base lesions through endonasal surgery, as used by our group.

The purpose of this study is to demonstrate the potential contribution of positron emission tomography (PET)/computed tomography (CT) to help differentiate olfactory neuroblastoma (ONB) from sinonasal undifferentiated carcinoma (SNUC).Following approval by the institutional review board at the Wexner Medical Center at the Ohio State University, Columbus, Ohio, a pilot study with retrospective review of patients with biopsy-proven diagnosis of ONB s and SNUC s was conducted. Staging PET/CT scans were reviewed to document the maximum standardized uptake value (SUVmax). A statistical comparison of SUVmax was performed.We identified 13 patients (7 with ONBs and 6 with SNUCs) with mean age 60.2 years who had undergone staging F-18 fluorodeoxyglucose (Maximum standardized uptake value of4. Laryngoscope, 2016 127:321-324, 2017.

Objectives Sinonasal cancers with neuroendocrine features share similar clinical, radiological, and histopathological features; however, these tumors often exhibit varying degrees of aggressive behavior presenting significant treatment challenges. The objective of this study was to report our experience with these rare malignancies and to present a review of current literature. Methods Following institutional review board approval, the records of all patients with biopsy-proven sinonasal malignancies over a 5-year period were reviewed. Results The study included 14 patients with olfactory neuroblastomas (ONBs), 7 patients with sinonasal undifferentiated carcinomas (SNUC), and 2 patients with sinonasal neuroendocrine carcinomas (SNEC). Histopathologic markers aided in final diagnosis, but showed variable specificity. In patients with sufficient follow-up, the 2-year disease-free survival rate was 81% (9/11) for ONB and 75% (3/4) for SNUC. Three patients developed a regional or distant recurrence (two with ONBs and one with SNUC). Two patients, one with SNEC and one with ONB, succumbed to brain radionecrosis related to proton radiation therapy. Conclusions Overlapping clinical and histopathological features in poorly differentiated sinonasal cancers with neuroendocrine features continue to present a diagnostic challenge. Individualized assessment and treatment strategies can improve the accuracy of the initial assessment and the treatment outcomes.

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.

A wealth of critical neurovascular structures within a relatively small surface area adds to the already intricate nature of skull base surgery. Surgical approaches to the area are difficult and often associated with significant morbidity and mortality. During the past two decades, endoscopic endonasal approaches (EEAs) have evolved to access the ventral skull base for the resection of tumors (benign and malignant), the decompression of neural structures including the cervicomedullary junction (pannus from rheumatoid arthritis or congenital anomalies, such as platybasia) and the reconstruction of skull base defects (cerebrospinal leaks, meningoencephalocele). These minimal access approaches obviate the need for external incisions, translocation of maxillofacial bones and retraction of the brain. Furthermore, EEAs yield improved visualization, which may reduce complications, and improve quality of life outcomes. Anatomical difficulties (e.g., vascular encasement or extension beyond the plane of a major vessel or cranial nerve), various special conditions (e.g., pediatric patients and vascular tumor) and limitation of institutional resources and technical difficulties may limit the use of EEAs. Thus, one should understand the indications and limitations of EEAs to optimize patient selection, which, in turn, may lead to superior surgical outcomes and reduced morbidity.

Object Symptomatic sellar arachnoid cysts (ACs) have typically been treated via the transsphenoidal route. After sellar cyst wall fenestration, some authors have advocated cyst wall resection and increasing communication between the AC and suprasellar subarachnoid space (SAS). This study is a report of the authors' experience using a simplified approach to reinforce a defective diaphragma sellae or unseen arachnoid diverticulum by deliberately not enlarging the AC-SAS communication and obliterating the cyst cavity with adipose tissue followed by skull base reconstruction. Methods A retrospective analysis was conducted of patients who underwent an endonasal transsphenoidal obliteration of symptomatic ACs with a fat graft and skull base repair. Results Between July 1998 and September 2010, 8 patients with a sellar AC were identified (6 women and 2 men, mean age 57 years). Clinical presentation included headache, pituitary dysfunction, and visual dysfunction (4 patients each group). Maximal cyst diameter averaged 22 mm (range 15–32 mm). In all cases the sellar communication to the SAS was deliberately not enlarged. The endoscope was used for visualization in 8 of 9 procedures. Postoperatively, headache improved in all 4 patients, vision in all 4 patients, and partial resolution of endocrine dysfunction (hyperprolactinemia and/or recurrent hyponatremia) occurred in 3 (75%) of 4 patients. No new endocrinopathy, CSF leak, meningitis, or neurological deficits occurred. Two patients experienced cyst reaccumulation: 1 symptomatic recurrence was treated with reoperation at 43 months postsurgery, and 1 asymptomatic partial recurrence continued to be monitored at 29 months postsurgery. Conclusions Sellar ACs can be effectively treated using endonasal fenestration and obliteration with fat with resultant reversal of presenting symptoms in the majority of patients. This simplified technique of AC cavity obliteration without enlarging communication to the SAS has a low risk of CSF leakage, and in most cases appears to effectively disrupt cyst progression, although longer follow-up is required to monitor for cyst recurrence.

The authors present a unique side-cutting instrument (NICO Myriad, Indianapolis, IN) with variable aspiration designed specifically for tumor resection. The study included retrospective review of data collected from 10/2009 to 01/2011. We detail the use of the Myriad in 31 patients with the following pathologies: meningioma (n=16), chordoma (n = 3), schwannoma (n = 3), pituitary adenoma (n = 2), metastasis (n = 3), hemangioblastoma (n = 1), craniopharyngioma (n = 1), and nasopharyngeal tumors (n = 2). Surgical approaches included expanded endonasal approach (n = 19), endoscopic brain port (n = 3), supraorbital “eyebrow” craniotomy (n = 3), retrosigmoid suboccipital craniotomy (n = 3), pterional craniotomy (n = 1), extreme far lateral (n = 1), and laminectomy (n = 1). Successful tumor resection was achieved in 30 cases. Instrument failure was noted in only one extremely fibrous meningioma. The design of this instrument facilitated maneuvering through narrow corridors while providing direct visualization of the suction aperture during tumor resection. These features allowed for tumor removal without injury to adjacent neurovascular structures. The side-cutting aspiration device allows safe and effective tumor removal. Its low profile, variable aspiration, and lack of thermal heat energy are particularly useful in tumor resection through narrow corridors, such as endonasal, port, and keyhole approaches. The multifunctional nature of the instrument (suction, scissors, and dissectors) minimizes multiple exchanges, facilitating tumor resection through these minimal access corridors.

Recent technological advances and growing cooperation between otorhinolaryngologists and neurosurgeons, coupled with an increasing knowledge of the anatomy of the ventral skull base, have led to the development of a series of surgical approaches to this region. Utilizing the nasal corridor, these expanded endonasal approaches (EEAs) benefit from the increased luminosity and definition provided by the endoscope to navigate through this corridor and reach a multitude o pathologies, both neoplastic and degenerative in nature. One of their common uses is to address tumors that arise from or invade the anterior cranial fossa; these lesions may include olfactory groove meningiomas, esthesioneuroblastomas and sinonasal malignancies. In order to safely resect these tumors through EEAs the surgical team must adhere to a series of steps, while planning the procedure as well as carrying it out. In this review article, the authors present these steps and describe the main patient selection criteria and complication avoidance strategies related to expanded endonasal approaches to the anterior skull base.

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.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.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) ).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.

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.

Introduction Various lateral and anterior approaches to access the infratemporal fossa (ITF) have been described. We provide our observations regarding the endoscopic transpterygoid and preauricular subtemporal approaches, listing their respective advantages and limitations through cadaveric dissection. Methods A cadaver study was performed on five adult specimens. An endoscopic transpterygoid approach to the ITF was completed bilaterally in three specimens, and an open preauricular ITF approach was performed bilaterally in two specimens. Results After completing the cadaveric dissections, we studied differences between the endoscopic transpterygoid approach and open preauricular subtemporal approaches in regard to exposure and ease of dissection of different structures in the ITF. Conclusions In comparison with a lateral approach, the endonasal endoscopic transpterygoid approach provides better visualization and more direct exposure of median structures such as the nasopharynx, eustachian tube, sella, and clivus. We concluded that the endoscopic transpterygoid approach can be utilized to resect benign lesions and some select group of malignancies involving the infratemporal and middle cranial fossae. Open approaches continue to play an important role, especially in the resection of extensive malignant tumors extending to these regions.

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.

Introduction: The endoscopic endonasal approach (EEA) has become an increasingly utilized means of addressing pathology at the craniovertebral junction (CVJ) as an alternative to the transoral-transpharyngeal approach (TOA). Although the EEA may offer decreased morbidity compared with the TOA, it is physically limited in its caudal working exposure by the nasal bone anteriorly and the hard palate posteriorly and thus offers restricted caudal access compared with the TOA. Objective: We hypothesized that performing an endoscopic endonasal partial posterior palatectomy would extend the inferior limit of the EEA caudally, thereby, increasing the working corridor to the upper cervical spine. Methods: A total of 10 formalin-fixed cadaveric specimens underwent high-resolution computed tomography (CT) scanning for registration to a stereotactic navigation device. These were assigned to one of two groups: one utilizing an angled drill and one utilizing a straight drill to perform bony resection. Using the navigation probe, the caudal-most limit of access with the assigned drill system to the anterior aspect of the vertebral bodies (AVB) and posterior aspect of the vertebral bodies (PVB) in the upper cervical spine were recorded. Then, the posterior hard palate was resected with the assigned drill from the midline maxillary crest to approximately halfway between midline and the medial maxillary sinus wall unilaterally on the side of the drill. This was done in 0.5 mm incremental resections with basion-to-AVB (b-AVB) and basion-to-PVB (b-PVB) measurements taken immediately afterward until no further caudal exposure was gained. The maximal gain in the b-AVB and b-PVB line was recorded for each specimen and averaged within each group of five specimens. Results: The average prepalatectomy b-AVB and b-PVB distances accessible to the straight drill were 18.74 and 20.96 mm respectively, and the postpalatectomy b-AVB and b-PVB distances were 29.88 and 36.24 mm. For the straight drill, the average caudal exposure gained with palatectomy was 11.14 mm to the AVB and 15.28 mm to the PVB. The average prepalatectomy b-AVB and b-PVB distances accessible to the angled drill were 28.84 and 38.04 mm, respectively, and the postpalatectomy b-AVB and b-PVB distances were 44.64 and 51.14 mm. For the angled drill, the average caudal exposure gained with palatectomy was 15.8 mm to the AVB and 13.1 mm to the PVB. Conclusion: Posterior palatectomy improved caudal access substantially when using both the straight and angled drills. Angled drills provided substantially improved caudal access via EEA compared with straight drills both with and without palatectomy. On the basis of our measurements, the additional caudal access gained for the straight drill was approximately equal to the b-AVB and b-PVB available to the angled drill without palatectomy.

Craniopharyngiomas are formidable tumors; their predilection for the suprasellar space and ability to adhere to surrounding structures renders their safe removal a daunting challenge. Several approaches have been proposed for their surgical treatment, including pterional-transsylvian, fronto-lateral, supraorbital, interhemispheric, subfrontal, transsphenoidal and even transpetrosal approaches. Recent advances in technology and a more thorough understanding of skull base anatomy from a ventral perspective have allowed the addition of the endonasal corridor under endoscopic visualization to the armamentarium of the skull base surgeon who deals with these lesions. The expanded endonasal approaches (EEAs), specifically the transsellar, transtuberculum, and transplanum modules, offer several advantages over their transcranial counterparts: direct visualization of the main tumor component and vital surrounding structures without the need for any brain or optic apparatus retraction is the main benefit over traditional techniques. The endonasal corridor grants ample access to the sellar and suprasellar compartments, as well as the anterior, middle, and posterior cranial fossae, when necessary. Direct visualization of the superior hypophyseal arteries, pituitary stalk and optic nerves and chiasm enables safe, microsurgical dissection of these structures from the tumor surface. Finally, the ventral perspective provides the surgeon with a superb view of the walls of the third ventricle, provided the tumor has violated them, a notoriously difficult area to safely access from a transcranial route.

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.

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.

Introduction: The frequency of lymphoma involving the central nervous system has been increasing over the last few decades, even among immunocompetent patients. Radiographically, lymphoma has been known to mimic different disease processes. Therefore, surgeons of the head and neck usually include this disease when formulating a differential diagnosis. We describe multiple cases of intracranial lymphoma that were initially consistent with other types of tumors and their surgical management as done via an endoscopic endonasal approach (EEA). Case Reports: Case #1: 69-year-old female presented with a several month history of headache and an associated 2 week history of double vision. An MRI of her brain showed a clival tumor with associated mass effect onto the cavernous sinuses bilaterally; the lesion was consistent with a chordoma. Via an EEA, a successful debulking of her cavernous sinus was achieved after her frozen section result showed evidence of lymphoma. Her final pathology was found to be diffuse large B cell lymphoma. Case #2: 57-year-old male presented with a history of headache and diplopia. A brain MRI was ordered that showed a heterogeneously enhancing clivus that appeared abnormally expanded. There was also extraosseous enhancement into the cavernous sinuses and superior orbital fissures bilaterally, the sella, as well as Meckel's cave on the left. He proceeded with an EEA and his superior orbital fissures were decompressed successfully. Final pathology was consistent with diffuse large B cell lymphoma. Case #3: 76-year-old male presented with a history of recent epistaxis. An MRI of his orbits was obtained which showed a mostly homogenously enhancing mass involving the left nasal cavity and bilateral ethmoid air cells. There was extension of this mass into the left sphenoid sinus and left orbit with associated enhancement of the skull base involving the cribiform plate and planum sphenoidale. He presented for an EEA to resect the mass. Frozen section was consistent with esthesioneuroblastoma. However, final pathology proved to be large B cell lymphoma. Case #4: 58-year-old male presented with a one-month history of deteriorating left eye function. He had an MRI of his brain completed which showed a large, heterogeneously enhancing lesion of his sella with invasion into the bilateral cavernous sinuses, greater on the left than the right. The most likely diagnosis given to the lesion based on imaging was a pituitary macroadenoma. He had an EEA done and frozen section corroborated this diagnosis. During the procedure, the left cavernous sinus and the superior orbital fissures were decompressed. Final histologic analysis revealed diffuse B cell lymphoma. Conclusion: Lymphoma should always be included in the differential when considering tumors that invade and expand normal osseous components and dural compartments of the intracranial space. Because patients with expansile skull base lesions typically have cranial nerve involvement, decompressing foramen or bone passages through which these nerve pass is an important goal during surgery to regain function. In our opinion, often biopsy alone is not sufficient to manage these patients' disease process.