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The study aims to evaluate the advantages of using endoscopic demonstrations to teach nose, paranasal sinuses, and skull base anatomy compared to traditional cadaveric demonstrations. Traditional dissection methods do not provide an accurate representation of in vivo visualization of these anatomical areas. The goal is to align the teaching approach with the perspective students will have during clinical practice for better clinical orientation. In this study, 100 first-year medical students were split into two groups: Group A and Group B, each with 50 students. Group A received teaching through endoscopic demonstrations, while Group B had cadaveric demonstrations, both focused on nose, paranasal sinuses, and skull base anatomy. To assess comprehension and clinical orientation, both groups completed a questionnaire with clinically relevant questions, and their responses were collected and compared for analysis. Students who received endoscopic training showed better accuracy in addressing clinical queries than those only exposed to cadaveric dissection. Many participants favored incorporating endoscopic instruction, either as a replacement or addition to traditional cadaveric dissection, for the studied topics. The endoscopically trained group performed better in understanding anatomical landmarks, mentally reconstructing 3D images, and conceptualizing surgical approaches for the targeted anatomical areas. Incorporating endoscopic training for the nasal cavity, paranasal sinuses and skull base into the undergraduate medical curriculum would substantially augment students' clinical understanding and provide a more profound grasp of the dynamic anatomy in these areas.

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INTRODUCTION: Endoscopic third ventriculostomy is a safe alternative to ventriculo-peritoneal shunt for certain cases of obstructive hydrocephalus. It has the advantage of not leaving a permanent foreign body in-situ, besides preventing over-drainage and reducing chances of infection. A thorough knowledge of endoscopic anatomy of ventricles is a must for performing various endoscopic procedures. OBJECTIVE: The aim of this study was to demonstrate the endoscopic anatomy of ventricles for educational purpose. PROCEDURE: ETV is done using a zero-degree LOTTA endoscope. Right Kocher's point is usually chosen as entry site into ventricle. The scope is negotiated into third ventricle through foramen of Monro. The premammillary membrane is perforated and dilated, thereby communicating the third ventricle to the chiasmatic, interpeduncular and prepontine cisterns. The video was recorded on Karl Storz recording system. It was edited using Imovie software. Photographs labeling was done using Windows PowerPoint 2018. CONCLUSION: Endoscopic anatomy knowledge allows a neurosurgeon to perform ETV safely.

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Otomicroscopic surgery remains the gold standard in the surgical treatment of patients with CHS. Endoscopic ear surgery is gaining more and more importance as an adjunct to microsurgery. Recently, thanks to the resolution of the endoscopic technique, endoscopic surgery can be used as an independent method. This article presents the results of endoscopic tympanoplasty, endoscopic removal of the tympanic cholesteatoma, performed on the basis of the otorhinolaryngology department of the Morozov Children's City Clinical Hospital. Research has shown that transcanal endoscopic surgery is an effective alternative to traditional otomicroscopic surgery. Advantage in minimal impact and improved visualization of all quadrants of the tympanic membrane, the anterior tympanomeatal angle of the NSP, and structures of the middle ear.

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Background: The traditional transcervical approach is frequently applied but limited in handling the tumors in parapharyngeal space.Objectives: We explore a new transcervical endoscopic approach with more direct visualization, less complications, and better outcomes.Material and methods: Eight cadaver heads (sixteen sides) were prepared for endoscopic dissection. Clinical cases were carefully selected, and thirty patients accepted the transcervical endoscopic surgery.Results: The transcervical approach with an endoscopic video system clearly exposed the detailed structures in the parapharyngeal space. The stylopharyngeus, styloglossus muscles, and styloid process were critical landmarks in this approach. During the thirty cases of clinical surgeries, internal carotid arteries and cranial nerves could be effectively exposed and protected with the endoscopic video system. Accurate hemostasis could be achieved under endoscopic transcervical approach with a mean amount between 30 to 100 ml of hemorrhaging. There was no postoperative hemorrhages and emergency tracheotomies. The follow up led to promising results.Conclusions and significance: The transcervical endoscopic approach provides a wide corridor for surgery in the parapharyngeal space. With accurate hemostasis, this approach can be applied as the first-line strategy for parapharyngeal surgeries in selected patients.

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PURPOSE: In the last decades, literature has shown an increasing interest in round windows (RW) anatomy due to its pivotal role in deafness surgery. The high variability of this anatomical region, with particular regard to the round windows niche (RWN), has been studied by several authors through different methods of investigation. The aim of the present research was to radiologically examine the morphological variability of the RWN and to link the imaging findings to the endoscopic view. METHODS: High-resolution CT scans of 300 temporal bones without neuro-otological pathologies were retrospectively reviewed by 2 neuroradiologist and 1 ENT surgeon who independently evaluated the RWN morphological variations. To link the radiological to the endoscopic data, 45 cadaveric human temporal bones were submitted to a radiological evaluation and to an otoendoscopy conducted through a posterior tympanotomy approach. RESULTS: Three variants of the RWN were detected on coronal CT scan reconstructions: 155 "cylindrical-type", 97 "j-type" and 48 "truncated cone-type". For each radiological type the endoscopic findings showed a specific endoscopic position of the RW chamber, which results in different degrees of RW membrane visibility when analysed through a posterior tympanotomy approach. CONCLUSIONS: To the best of our knowledge, this is the first description of the above-mentioned RWN radiological variations supported by endoscopic data. This study suggests an additional anatomical evaluation that could be useful to predict the RW membrane visibility through a posterior tympanotomy approach. Further studies are required to support the clinical implications of our observations.

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OBJECTIVE: The minimally invasive microvascular decompression (MVD) for trigeminal neuralgia is technically a more challenging operation compared with the standard retrosigmoidal approach. Endoscopic assistance could help to widen the field of view of the microscope during MVD. An extended view around the cisternal segment of the trigeminal nerve can be achieved only with the targeted dissection of the arachnoid membranes. The goal of our study was to analyze the three-dimensional organization of these membranes around the trigeminal nerve. METHODS: Microsurgical, endoscopic, and macroscopic anatomic examinations were performed on 50 fresh human cadaveric specimens. Retrospective analysis of the video documentations of 50 MVDs was performed to describe the surgical relevance of the examined membranes. RESULTS: The trigeminal nerve is surrounded circumferentially by 4 inner arachnoid membranes: laterally and caudally by the trigeminal membrane (TM), cranially by the superior cerebellar membrane (SCM), and medially by the junction between the cranial edge of the anterior pontine membrane and the lateral edge mesencephalic leaf of the Liliequist membrane complex. The superior cerebellar artery was located in every case cranial from the SCM. This membrane served as a safety plane to dissect the vessel from the nerve. The SCM was laterally adherent to the TM, which made the arachnoid dissection challenging. The superior petrosal vein was located cranially and laterally from the described inner arachnoid membranes, but the transverse pontine vein was embedded into the membrane complex. CONCLUSIONS: Knowledge of the described anatomy of the arachnoid membranes around the trigeminal nerve is essential to safely perform an MVD.

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Background The aim of our study was a pictorial documentation of the anatomical structures of the orbit. Methods We performed a transmaxillary endoscopic approach in nine formalin-fixed human heads. We identified and documented the anatomy of the inferior part of the orbit. Results The first intraorbital anatomical landmark was the inferior rectus muscle, from which important structures medially and laterally could be identified. Anatomical structures and their relation to each other were documented and presented as illustrative figures. Conclusion Knowledge of the topographic anatomy of the inferior part of the orbit could be sufficiently imparted by our illustrations. The presented transmaxillary approach allowed a wide overview of the anatomical structures located in the inferior part of the orbit. Our pictorial documentation may provide neurosurgeons more safety and the opportunity to become familiar with the endoscopic anatomy.

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We have undertaken the analysis of the specific clinical manifestations of acquired cholesteatoma of the middle ear in 437 chronic patients suffering from this pathology. 96.1% of them presented with primarily acquired cholesteatoma of the middle ear (including 53.3% having attic cholesteatoma, 22.8% with sinus cholesteatoma, and 19.9% of tensa retraction cholesteatoma). 3.9% of the patients exhibited a different mechanism of development of cholesteatoma. The secondary acquired mesotympanic cholesteatoma formed in association with the long-term chronic inflammation of the middle ear, concomitant perforation of the tympanic membrane and epithelial invasion from the edge of the tympanic membrane perforation and middle ear cavity. Typmanosclerosis of different degree and localization played an important role in the enhancement of the prevalence of this condition. All types of acquired cholesteatoma were found to extend beyond the point of origin of the disorder. The maximum destruction of the ossicular chain was documented in the patients presenting with sinus cholesteatoma. Those with secondary acquired cholesteatoma showed the worst functional capacity as a result of rigid fixation of the auditory ossicles. The overall cholesteatoma relapse rate (including both residual and recurrent cholesteatoma) was estimated to be 15.6%. It is concluded that the surgical strategy should be chosen on an individual basis for each concrete patient. The long-term observation of the treated patients with the application of the up-to-date radiological techniques is believed to be the indispensable prerequisite for the successful management of the complicated pathology under consideration.

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The objective of the present work was to study the specific endoscopic anatomical features of the middle ear using the dissected temporal bones with the intact tympanic membrane. The 18 cm long endoscopes 4 mm in diameter with a visual angle from 0 to 45 degrees in the combination with some other microinstruments, such as ear pincers, needles, curettes, elevators, and suction tubes, were used during the examination. It was shown that endomeato-transtympanic endosopy provides a panoramic view of almost all structures of the middle ear. After the resection of the posterior bone edge of 'annulus tympanicus', the use of the 45o endoscope ensured the panoramic view not only of certain structures of the middle ear (e.g. the tympanic chord, the stapedius muscle tendon, the entire pyramidal process) but also of the structures of the retrotympanic and anterior epitympanic spaces.

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PURPOSE: The endoscopic bidimensional vision offered by the endoscope during endoscopic sinus surgery involves difficulty in visualizing surgical field depth which makes it difficult to learn this surgical technique and makes it necessary for the endoscopic surgeon to mentally create a three-dimensional (3D) picture of the paranasal sinuses anatomy. In particular, frontal recess surgery requires good knowledge of its anatomic position, also since it is necessary to use angled endoscopes, which distort the view, and angular instruments which are difficult to use. Purpose of this project is to offer to the endoscopic surgeon a detailed 3D model of the nose and paranasal sinuses with particular attention to the frontal recess. METHODS: A 3D reconstruction of the frontal recess and its related structures, starting from computer tomography scans of the human skull, was realized using a professional 3D graphics software. RESULTS: A detailed reconstruction of the main structures which contribute to form the frontal recess was obtained. Particular attention was paid when reproducing the agger nasi cells, uncinate process, ethmoidal bulla, anterior ethmoidal cells, frontoethmoidal cells and their anatomic variants. CONCLUSIONS: This is the first experience reported in literature regarding this new technique of iconographic didactics applied to endoscopic sinus surgery. It represents a new frontier, which surpasses and integrates the previous didactic techniques to help the surgeon to mentally create a 3D image of the paranasal sinuses.

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OBJECTIVE The application of the endoscope in the lateral skull base increases the importance of the middle ear cavity as the corridor to the skull base. The aim of this study was to define the middle ear as a route to the fundus (lateral end) of the internal acoustic canal and to propose feasible landmarks to the fundus. METHODS This was a cadaveric study; 34 adult cadaveric temporal bones and 2 dry bones were dissected with the aid of the endoscope and microscope to show the anatomy of the transcanal approach to the middle ear and fundus of the internal acoustic canal. RESULTS In the middle ear cavity, the cochleariform process is one of the key landmarks for accessing the fundus of the internal acoustic canal. The triangle formed by the anterior and posterior edges of the overhang of the round window and the cochleariform process provides a landmark to start drilling the bone to access the fundus of the internal acoustic canal. CONCLUSIONS The external acoustic canal and middle ear cavity combined, using endoscopic guidance, can provide a route to the fundus of the internal acoustic canal. A triangular landmark crossing the promontory has been described for reaching the meatal fundus. This transcanal approach requires an understanding of the relationship between the middle ear cavity and the fundus of the internal acoustic canal and provides a potential new area of cooperation between otology and neurosurgery for accessing pathology in this and the bordering skull base.

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OBJECTIVE A common approach to lesions of the pineal region is along the midline below the torcula. However, reports of how shifting the approach off midline affects the surgical exposure and relationships between the tributaries of the vein of Galen are limited. The purpose of this study is to examine the microsurgical and endoscopic anatomy of the pineal region as seen through the supracerebellar infratentorial approaches, including midline, paramedian, lateral, and far-lateral routes. METHODS The quadrigeminal cisterns of 8 formalin-fixed adult cadaveric heads were dissected and examined with the aid of a surgical microscope and straight endoscope. Twenty CT angiograms were examined to measure the depth of the pineal gland, slope of the tentorial surface of the cerebellum, and angle of approach to the pineal gland in each approach. RESULTS The midline supracerebellar route is the shortest and provides direct exposure of the pineal gland, although the culmen and inferior and superior vermian tributaries of the vein of Galen frequently block this exposure. The off-midline routes provide a surgical exposure that, although slightly deeper, may reduce the need for venous sacrifice at both the level of the veins from the superior cerebellar surface entering the tentorial sinuses and at the level of the tributaries of the vein of Galen in the quadrigeminal cistern, and require less cerebellar retraction. Shifting from midline to off-midline exposure also provides a better view of the cerebellomesencephalic fissure, collicular plate, and trochlear nerve than the midline approaches. Endoscopic assistance may aid exposure of the pineal gland while preserving the bridging veins. CONCLUSIONS Understanding the characteristics of different infratentorial routes to the pineal gland will aid in gaining a better view of the pineal gland and cerebellomesencephalic fissure and may reduce the need for venous sacrifice at the level of the tentorial sinuses draining the upper cerebellar surface and the tributaries of the vein of Galen.

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Endoscopy in cerebellopontine angle surgery is an increasingly used technique. Despite of its advantages, the shortcomings arising from the complex anatomy of the posterior fossa are still preventing its widespread use. To overcome these drawbacks, the goal of this study was to define the anatomy of different endoscopic approaches through the retrosigmoid craniotomy and their limitations by surgical windows. Anatomical dissections were performed on 25 fresh human cadavers to describe the main approach-routes. Surgical windows are spaces surrounded by neurovascular structures acting as a natural frame and providing access to deeper structures. The approach-routes are trajectories starting at the craniotomy and pointing to the lesion, passing through certain windows. Twelve different windows could be identified along four endoscopic approach-routes. The superior route provides access to the structures of the upper pons, lower mesencephalon, and the upper neurovascular complex through the suprameatal, superior cerebellar, and infratrigeminal windows. The supratentorial route leads to the basilar tip and some of the suprasellar structures via the ipsi- and contralateral oculomotor and dorsum sellae windows. The central endoscopic route provides access to the middle pons and the middle neurovascular complex through the inframeatal, AICA, and basilar windows. The inferior endoscopic route is the pathway to the medulla oblongata and the lower neurovascular complex through the accessory, hypoglossal, and foramen magnum windows. The anatomy and limitations of each surgical windows were described in detail. These informations are essential for safe application of endoscopy in posterior fossa surgery through the retrosigmoid approach.

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The round window region is of critical importance in the anatomy of the middle ear. The aim of this paper is to describe its anatomy from an endoscopic point of view, emphasizing structures that have important surgical implications, in particular the fustis and the subcochlear canaliculus. The fustis, a smooth bony structure that forms the floor of the round window region, is a constant and important structure. It seems to indicate the round window membrane and the correct position of scala tympani. A structure connecting the round window region to the petrous apex, named the subcochlear canaliculus, is also described. A retrospective review of video recordings of endoscopic dissection and surgical procedures, carried out between June 2014 and February 2015, was conducted across two Tertiary university referral centers. A total of 42 dissections were analyzed in the study. We observed the fustis in all the cases and we identify two different anatomical conformations. The subcochlear canaliculus was found in 81.0 %, with a pneumatization direct to the petrous apex in 47.7 %. Conformation and limits of the round window niche may influence the surgical view of the round window membrane. Endoscopic approaches allow a very detailed view, which enables a comprehensive exploration of the round window region. Accurate knowledge of the anatomical relationships of this region has important advantages during middle ear surgery.

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OBJECT: The temporal horn of the lateral ventricle is a complex structure affected by specific pathological conditions. Current approaches to the temporal horn involve a certain amount of corticotomy and white matter disruption. Surgeons therefore set aside anterior temporal lobectomy as a last resource and avoid it in the dominant hemisphere. The authors propose a minimally invasive endoscopic intraventricular approach to the temporal horn and describe a standardized analysis and technical assessment of the feasibility of this approach. METHODS: To determine the best trajectory, angulation, and entry point to the temporal horn of the lateral ventricle, the authors evaluated 50 cranial MRI studies (100 temporal lobes) from healthy patients. They studied and systematized the neurosurgical endoscopic anatomy. They also simulated the proposed approach in 9 cadaveric specimens (18 approaches). RESULTS: Mean scalp entry point coordinates (± SD) were 2.7 ± 0.28 cm lateral to the inion and 5.6 ± 0.41 cm superior to the inion. The mean total distance from the uncal recess to the scalp (± SD) was 10.64 ± 0.6 cm. The mean total intraparenchymal distance crossed by the endoscope was 3.76 ± 0.36 cm. The approach was successfully completed in all studied specimens. CONCLUSIONS: In this study, the endoscopic intraventricular approach to the temporal horn is standardized. The morphometric analysis makes this approach anatomically feasible and replicable. This approach provides minimally invasive endoscopic access to the uncal recess, amygdala, hippocampus, fornix, and paraventricular temporal lobe structures. The following essential strategies enabled access to and maneuverability inside the temporal horn: tailored preoperative planning of the trajectory and use of anatomical and radiological references, constant irrigation, and an angled endoscopic lens. Safety assessment and novel instruments and techniques may be proposed to advance this very promising route to pathological changes in the temporal lobe.

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INTRODUCCIÓN: las indicaciones de la cirugía endoscópica endonasal en el tratamiento de tumores de base de cráneo continúan expandiéndose, sobre todo para los tumores extradurales, como son los cordomas. A partir de un caso, nuestro objetivo fue revisar la literatura relevante de estos desafiantes tumores operados bajo esta técnica. CASO CLÍNICO: paciente de 59 de edad con antecedentes de depresión mayor, que comenzó con un cuadro de diplopía por compromiso del VI par izquierdo. Los estudios (CT y RM) mostraron un proceso expansivo en la región del ápex petroso. Se realizó un abordaje endoscópico extendido a la región petro-clival con resección tumoral subtotal. Buena evolución postquirúrgica con desaparición de su diplopía. El diagnóstico histológico fue de Cordoma Condroide. Se indicó radioterapia adyuvante. DISCUSIÓN: a partir del conocimiento y la experiencia en el manejo endoscópico de la patología intraselar se desarrollaron abordajes para el tratamiento de patologías que comprometen la fosa anterior, media e inclusive la fosa posterior. Actualmente, los abordajes endoscópicos, se han extendido a otras áreas de la base de cráneo que de otro modo presentan un reto técnico para la exposición a través de los abordajes transcraneales habituales. El abordaje endoscópico endonasal ofrece una ruta quirúrgica adecuada para la resección del tumor que se presenta en este caso. Las vías que pueden ser utilizados para llegar a la región petroclival a través de la acceso endonasal incluyen la medial (con o sin la movilización de ACI) y la infrapetrosa transterigoidea. En este reporte de caso se analizan las indicaciones del abordaje endoscópico endonasal basado en una revisión de la literatura. CONCLUSIÓN: el abordaje endoscópico endonasal extendido se presenta como una alternativa segura para el tratamiento de determinadas lesiones petro-clivales. Se requieren más estudios anatómicos y clínicos para establecer mejor el rol de este tipo de técnicas en el manejo de las lesiones localizadas en esta región

INTRODUCTION: indications for endoscopic endonasal surgery for the treatment of skull base tumors continue to expand, particularly for extradural tumors, such as chordomas. Based on this case report presentation, we aim to review the literature on the endoscopic technique relevant to the management of these challenging tumors. CASE REPORT: a 59 year-old woman who presented with diplopia due to left sixth nerve palsy underwent imaging studies (CT, MRI) that revealed a mainly intra-osseous expansive process of the left petrous apex. An expanded endoscopic endonasal approach to the petroclival region was performed and the tumor was subtotally resected. The patient recovered from surgery with resolved diplopia. Histopathology was compatible with chondroid chordoma. The radiation therapy was indicated after surgery. DISCUSSION: built upon the bulk experience on the treatment of intrasellar pathology, endonasal endoscopic approaches have been developed for the treatment of skull base lesions involving the anterior, middle and even posterior cranial fossae. Nowadays, the use of these techniques has spread to other areas of the skull base, which otherwise present as a formidable technical challenge for exposure through transcranial approaches. The endonasal endoscopic approach provides an adequate surgical corridor for the resection of the tumor presented in this case report. The alternative corridors that can be utilized to reach the petroclival region through the endonasal endoscopic route include the medial corridor (with or without ICA mobilization) and the transpterygoid infrapetrous corridor. In this article, we discuss the indications for the endoscopic endonasal approach for the case presented, and discuss our choice of approach based on our review of the literature. CONCLUSION: the extended endoscopic endonasal approach presents as a safe alternative for the treatment of select petroclival lesions. Further anatomical and clinical studies are required to better establish the role of the endoscopic endonasal approach for lesions located in this region

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The midline skull base is an anatomical area, which extends from the anterior limit of the anterior cranial fossa down to the anterior border of the foramen magnum. For many lesions of this area, a variety of skull base approaches including anterior, antero-lateral, and postero-lateral routes, have been proposed over the last decades, either alone or in combination, often requiring extensive neurovascular manipulation. Recently the endoscopic endonasal approach to the skull base has been introduced to access the midline skull base. The major potential advantage of the endoscopic endonasal technique is to provide a direct anatomical route to the lesion since it does not traverse any major neurovascular structures, thereby obviating brain retraction. The potential disadvantages include the relatively restricted exposure and the higher risk of CSF leak. In the present study we report the endoscopic endonasal anatomy of different areas of the midline skull base from the olfactory groove to the cranio-vertebral junction and accordingly describe the main features of the surgical approaches to each of these regions.

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Objective To study the identification of the endoscopic anatomical landmarks in the unilateral endoscopic endonasal transsphenoidal approach, and discuss the verification of the anterior wall of the sphenoid sinus and expansion of the bone exposure of the sellar region according to different growth patterns of the selhr tumors. Methods Ten formalin-fixed adult cadaveric heads and 5 fresh cadaveric heads wefe perfused with red silicone through the internal carotid artery.and blue glass cement was perfused through the internal jugular vein.The endoscope Was introduced through the unilateral nasal cavity, and the contralateral nasal cavity was fully exposed by removing the superficial nasofacial structures for observation and measurement. Results The distance from the phatyngopalatine arch to the inferior edge of the sphenoidal ostium Was 15.13±1.99 mm,and that from the inferior edge of the posterior middle turbinate to the center of the sellar floor Was 10.20±0.15 mm.The content of the sphenoid sinus Was 8.73±2.90 mL after removal ofthe compartment of the sphenoid sinus,with the sellar floor thickness of 3.68±1.96 mm.The angles between the nasal septurn and the anterior wall of the sphenoid sinus varied significantly on different planes(P＜0.05).Conclusion When difficult to locate the sphenoidal ostium,the opening site can be determined by observing the peculiar oval protuberance on the anterior wall of the sphenoid sinus.the relationship between the anterior wall of the sphenoid sinus and the middle turbinate,and the average distance from the superior limit of the pharyngopalatine arch to the sphenoidal ostiam.The voger on the midline position can be used as the landmark of the midline of the sellar floor.When the tumor has an extrasellar portion,as in the planum sphenoidale,the modified enlarged approach can be the choice.