Anatomical study of the pterygopalatine fossa using an endoscopic endonasal approach: spatial relations and distances between surgical landmarks

An endoscopic transnasal prelacrimal recess transmaxillary approach to the pterygopalatine fossa and infratemporal fossa

Objective

In this paper, the goal of the authors is to present the anatomic nuances and their clinical experience with lesions of the pterygopalatine fossa and infratemporal fossa using an endoscopic transnasal prelacrimal recess transmaxillary approach (PLRMA).

Methods

An endoscopic anatomical dissection of three fresh cadaveric heads was performed bilaterally to evaluate the feasibility of the PLRMA. Prior to dissection, stereotactic computed tomography scans were obtained for each head to obtain anatomical measurements. The area of exposure on the posterior wall of the maxillary sinus was determined using stereotaxis. The cases of six patients with schwannomas or epidermoid cysts who underwent the transnasal PLRMA were illustrated.

Results

The mean area of exposure on the posterior wall of the maxillary sinus was 9.55 cm2. Total resection was achieved in all six patients. The mean follow-up time was 16 months, and one patient complained of postoperative facial numbness, which resolved gradually. No cases of chronic sinusitis were reported.

Conclusions

The endoscopic transnasal PLRMA provides efficient operative exposure to the pterygopalatine fossa and infratemporal fossa. Preserving the integrity of the mucosa on the nasal lateral wall is an advantage of this approach.

Endoscopic-assisted en-bloc pterygomaxillectomy: Identifying an efficient and safe location for the pterygoid osteotomy

BACKGROUND

For aggressive maxillary sinus and pterygopalatine fossa (PPF) tumors, an en-bloc pterygomaxillectomy may be indicated.

METHODS

Five head specimens were used to study the feasibility of an en-bloc pterygomaxillectomy. Eighty-five non-pathological CT scans were used to compare the superior edge of the inferior turbinate (IT) and the middle turbinate tail (MT) as landmarks for the pterygoid osteotomy.

RESULTS

Through a combined sublabial-subperiosteal incision and transoral route, a mid-sagittal osteotomy through the hard palate and an axial osteotomy below the infraorbital foramen were performed. For the endoscopic pterygoid osteotomy, an infra-vidian transpterygoid approach was performed, subsequently removing the pterygomaxillectomy en-bloc. As landmarks, the osteotomies at the level of the MT tail and IT resected the pterygoid plates completely, but the IT osteotomy was further away from the vidian canal (7.5 vs. 6 mm).

CONCLUSIONS

The endoscopic-assisted en-bloc pterygomaxillectomy is feasible. The IT landmark is safe and ensures complete resection of the pterygoid plates.

Reconstruction of Anophthalmic Sockets With Pedicled Nasoseptal Flap

PURPOSE

Patients who undergo eye removal often present with orbital soft-tissue insufficiency and contraction of the eye sockets. The most commonly used reconstruction strategy is grafting the orbit with free grafts, which is associated with the drawback of harvesting tissue from an unconnected site. This study describes the use of the vascularized nasoseptal flap in the reconstruction and enlargement of the contracted anophthalmic cavity in patients with severe or recurrent contracted eye sockets and evaluates its efficacy.

METHODS

A sphenopalatine-pedicled flap from the nasal septum was harvested and mobilized into the anophthalmic orbit for the reconstruction, coverage, and enlargement of the socket in 17 patients with anophthalmic socket syndrome. Data regarding the demographics, preoperative status, postoperative findings, follow-up, outcomes, dates of mutilant and reconstructive surgery, and relevant clinical or imaging were collected.

RESULTS

Krishna´s classification was used to assess the postoperative outcomes. The final rating improved in all patients at a median follow-up duration of 35 months. A greater impact was observed in patients who underwent reconstructive surgery before nasoseptal flap creation. Two minor complications occurred; however, major surgical intervention was not required. Implant extrusion was observed in 2 patients.

CONCLUSIONS

The novel strategy of applying nasoseptal flaps in the reconstruction of anophthalmic sockets results in improved socket grading and a low rate of recurrence (socket contracture or implant extrusion), and complications. The vascular nature of the flap makes it suitable for use in complex cases.

Infra-Temporal and Pterygo-Palatine Fossae Tumors: A Frontier in Endoscopic Endonasal Surgery—Description of the Surgical Anatomy of the Approach and Report of Illustrative Cases

Infratemporal and pterygopalatine fossae (ITF and PPF) represent two complex paramedian skull base areas, which can be defined as jewelry boxes, containing a large number of neurovascular and osteomuscular structures of primary importance. They are in close communication with many craniofacial areas, such as nasal/paranasal sinuses, orbit, middle cranial fossa, and oral cavities. Therefore, they can be involved by tumoral, infective or inflammatory lesions spreading from these spaces. Moreover, they can be the primary site of the development of some primitive tumors. For the deep-seated location of ITF and PPF lesions and their close relationship with the surrounding functional neuro-vascular structures, their surgery represents a challenge. In the last decades, the introduction of the endoscope in skull base surgery has favored the development of an innovative anterior endonasal approach for ITF and PPF tumors: the transmaxillary-pterygoid, which gives a direct and straightforward route for these areas. It has demonstrated that it is effective and safe for the treatment of a large number of benign and malignant neoplasms, located in these fossae, avoiding extensive bone drilling, soft tissue demolition, possibly unaesthetic scars, and reducing the risk of neurological deficits. However, some limits, especially for vascular tumors or lesions with lateral extension, are still present. Based on the experience of our multidisciplinary team, we present our operative technique, surgical indications, and pre- and post-operative management protocol for patients with ITF and PPF tumors.

Extended endonasal approaches for pituitary adenomas

Pituitary adenomas with significant extension beyond the sellar boundary, large size, asymmetrical shape and subarachnoid space invasion, although rare, represent a therapeutic challenge. The invasiveness of the tumor itself often limits the potential for complete tumor resection and increases the likelihood of intraoperative or postoperative complications, regardless of the approach. The extended endoscopic endonasal approach has been proposed as a valid alternative to the transcranial route for the treatment of certain pituitary adenomas not suitable to the standard transsphenoidal approach. Thanks to the wide and close up view provided by the endoscope via the appropriate expanded bone removal at the skull base, this technique offers, in an adequate working space, a safe exposure of the tumor and surrounding anatomical structures, at the supra-, para-, and retro-sellar areas. It stands clear that the primary goal of this approach remains the maximum allowed resection with preservation of neurological and endocrine functions. Herein, we debate the extended endoscopic endonasal technique for the treatment of pituitary adenomas, with the aim of underlying its indications, pitfalls, advantages, and limitations.

Endoscopic endonasal treatment of maxillary nerve (V2) painful neuropathy: cadaveric study with clinical correlation

BACKGROUND

Surgical access to the second (V2, maxillary) and third (V3, mandibular) branches of the trigeminal nerve (V) has been classically through a transoral approach. Increasing expertise with endoscopic anatomy has achieved less invasive, more efficient access to skull base structures. The authors present a surgical technique using an endoscopic endonasal approach for the treatment of painful V2 neuropathy.

METHODS

Endoscopic endonasal dissections using a transmaxillary approach were performed in four formalin-fixed cadaver heads to expose the V2 branch of the trigeminal nerve. Relevant surgical anatomy was evaluated and anatomic parameters for neurectomy were identified.

RESULTS

Endoscopic endonasal transmaxillary approaches completed bilaterally to the pterygopalatine and pterygomaxillary fossae exposed the V2 branch where it emerged from the foramen rotundum. The anatomy defined for the location of neurectomy was determined to be the point where V2 emerged from the foramen rotundum into the pterygopalatine fossa. The technique was then performed in 3 patients with intractable painful V2 neuropathy.

CONCLUSIONS

In our cadaveric study and clinical cases, the endoscopic endonasal approach to the pterygopalatine fossa achieved effective exposure and treatment of isolated V2 painful neuropathy. Important surgical steps to visualize the maxillary nerve and its branches and key landmarks of the pterygopalatine fossa are discussed. This minimally invasive approach appears to be a valid alternative for select patients with painful V2 trigeminal neuropathy.

Refining the anatomic boundaries of the endoscopic endonasal transpterygoid approach: the "VELPPHA area" concept

OBJECTIVE

The endoscopic endonasal transpterygoid route has been widely evaluated in cadavers, and it is currently used during surgery for specific diseases involving the lateral skull base. Identification of the petrous segment of the internal carotid artery (ICA) is a key step during this approach, and the vidian nerve (VN) has been described as a principal landmark for safe endonasal localization of the petrous ICA at the level of the foramen lacerum. However, the relationship of the VN to the ICA at this level is complex as well as variable and has not been described in the pertinent literature. Accordingly, the authors undertook this purely anatomical study to detail and quantify the peri-lacerum anatomy as seen via an endoscopic endonasal transpterygoid pathway.

METHODS

Eight human anatomical specimens (16 sides) were dissected endonasally under direct endoscopic visualization. Anatomical landmarks of the VN and the posterior end of the vidian canal (VC) during the endoscopic endonasal transpterygoid approach were described, quantitative anatomical data were compiled, and a schematic classification of the most relevant structures encountered was proposed.

RESULTS

The endoscopic endonasal transpterygoid approach was used to describe the different anatomical structures surrounding the anterior genu of the petrous ICA. Five key anatomical structures were identified and described: the VN, the eustachian tube, the foramen lacerum, the petroclival fissure, and the pharyngobasilar fascia. These structures were specifically quantified and summarized in a schematic acronym-VELPPHA-to describe the area. The VELPPHA area is a dense fibrocartilaginous space around the inferior compartment of the foramen lacerum that can be reached by following the VC posteriorly; this area represents the posterior limits of the transpterygoid approach and, of utmost importance, no neurovascular structures were observed through the VELPPHA area in this study, indicating that it should be a safe zone for surgery in the posterior end of the endoscopic endonasal transpterygoid approach.

CONCLUSIONS

The VELPPHA area represents the posterior limits of the endoscopic endonasal transpterygoid approach. Early identification of this area can enhance the safety of the endoscopic endonasal transpterygoid approach expanded to the lateral aspect of the skull base, especially when treating patients with poorly pneumatized sphenoid sinuses.

Endoscopic endonasal approach for mass resection of the pterygopalatine fossa

OBJECTIVES

Access to the pterygopalatine fossa is very difficult due to its complex anatomy. Therefore, an open approach is traditionally used, but morbidity is unavoidable. To overcome this problem, an endoscopic endonasal approach was developed as a minimally invasive procedure. The surgical aim of the present study was to evaluate the utility of the endoscopic endonasal approach for the management of both benign and malignant tumors of the pterygopalatine fossa.

METHOD

We report our experience with the endoscopic endonasal approach for the management of both benign and malignant tumors and summarize recent recommendations. A total of 13 patients underwent surgery via the endoscopic endonasal approach for pterygopalatine fossa masses from 2014 to 2016. This case group consisted of 12 benign tumors (10 juvenile nasopharyngeal angiofibromas and two schwannomas) and one malignant tumor.

RESULTS

No recurrent tumor developed during the follow-up period. One residual tumor (juvenile nasopharyngeal angiofibroma) that remained in the cavernous sinus was stable. There were no significant complications. Typical sequelae included hypesthesia of the maxillary nerve, trismus, and dry eye syndrome.

CONCLUSION

The low frequency of complications together with the high efficacy of resection support the use of the endoscopic endonasal approach as a feasible, safe, and beneficial technique for the management of masses in the pterygopalatine fossa.

Infraorbital nerve: a surgically relevant landmark for the pterygopalatine fossa, cavernous sinus, and anterolateral skull base in endoscopic transmaxillary approaches

OBJECTIVE

Endoscopic transmaxillary approaches (ETMAs) address pathology of the anterolateral skull base, including the cavernous sinus, pterygopalatine fossa, and infratemporal fossa. This anatomically complex region contains branches of the trigeminal nerve and external carotid artery and is in proximity to the internal carotid artery. The authors postulated, on the basis of intraoperative observations, that the infraorbital nerve (ION) is a useful surgical landmark for navigating this region; therefore, they studied the anatomy of the ION and its relationships to critical neurovascular structures and the maxillary nerve (V2) encountered in ETMAs.

METHODS

Endoscopic anatomical dissections were performed bilaterally in 5 silicone-injected, formalin-fixed cadaveric heads (10 sides). Endonasal transmaxillary and direct transmaxillary (Caldwell-Luc) approaches were performed, and anatomical correlations were analyzed and documented. Stereotactic imaging of each specimen was performed to correlate landmarks and enable precise measurement of each segment.

RESULTS

The ION was readily identified in the roof of the maxillary sinus at the beginning of the surgical procedure in all specimens. Anatomical dissections of the ION and the maxillary branch of the trigeminal nerve (V2) to the cavernous sinus suggested that the ION/V2 complex has 4 distinct segments that may have implications in endoscopic approaches: 1) Segment I, the cutaneous segment of the ION and its terminal branches (5–11 branches) to the face, distal to the infraorbital foramen; 2) Segment II, the orbitomaxillary segment of the ION within the infraorbital canal from the infraorbital foramen along the infraorbital groove (length 12 ± 3.2 mm); 3) Segment III, the pterygopalatine segment within the pterygopalatine fossa, which starts at the infraorbital groove to the foramen rotundum (13 ± 2.5 mm); and 4) Segment IV, the cavernous segment from the foramen rotundum to the trigeminal ganglion (15 ± 4.1 mm), which passes in the lateral wall of the cavernous sinus. The relationship of the ION/V2 complex to the contents of the cavernous sinus, carotid artery, and pterygopalatine fossa is described in the text.

CONCLUSIONS

The ION/V2 complex is an easily identifiable and potentially useful surgical landmark to the foramen rotundum, cavernous sinus, carotid artery, pterygopalatine fossa, and anterolateral skull base during ETMAs.

Location of Pterygopalatine Fossa and its Relationships to the Structures in Sellar Region

PURPOSE

The aim of this study is to locate pterygopalatine fossa (PPF) and the opening of its communicating canals by accessing the relationship between PFF and the endoscopic landmarks such as the tubercular recess (TR) and middle lowest point of sellar floor (SF) as well as analyze the relation between PPF and important structures such as internal carotid artery (ICA) and optic canal (OC).

MATERIALS AND METHODS

Computer topographic angiography (CTA) images of 118 PPF regions were reviewed. The measurement was on coronal, sagittal, and axial planes after multiplanar reconstruction (MPR). The location of PPF and its relationship to the sphenoid sinus, ICA, and OC were studied. The communicating canals of PPF, which were related to the transsphenoid approach, were three-dimensionally measured by the stationary structures, such as the middle lowest point of SF, the sagittal midline, and the top and bottom wall of sphenoid sinus.

RESULT

The posterior part of PPF was located by the middle lowest point of SF. The anterior opening of sphenopalatine foramen (SPF), pterygoid canal (PC), palatovaginal canal (PVC), and foramina rotundum (FR) have relative stationary position, which can be located by the landmarks of sellar region during the endoscopic surgery.

CONCLUSIONS

Pterygopalatine fossa is related to numerous neurovascular structures. Accurate understanding of the radiologic anatomy of PPF is beneficial for the PPF disease diagnosis, the selection of treatment plan and the prognosis evaluation.

Ascertain the Safe Range From Foramen Rotundum to the Siphon of Internal Carotid Artery for Operation Through Pterygopalatine Fossa With Thin-Section Computed Tomographic Image

OBJECTIVE

This study aimed to ascertain the safe range from foramen rotundum to the siphon of internal carotid artery using three-dimensional reconstruction technique.

METHODS

We scanned skulls of 121 volunteers to get the final results with thin-section computed tomographic image.

RESULTS

The distance of AC was measured as 13.22 (3.79) mm (range, 8.33-105.67 mm; 95% CI [confidence interval], 8.55-21.39 mm). The angle to the sagittal plane was measured as 33.54 (9.23) mm (range, 5.38-66.58; 95% CI, 30.88-34.20). The angle to the coronal plane was measured as 53.17 (10.48) mm (range, 5.60-75.02; 95% CI, 51.29-55.06). The angle to the horizontal plane was measured as 9.43 (12.91) mm (range, -28.44 to 82.22; 95% CI, 7.11-11.76).

CONCLUSIONS

These above-mentioned results can help locate these structures to help in minimizing surgical trauma to the nerves and blood vessels of the operation through pterygopalatine fossa under nasoendoscope.

Endoscopic transnasal approaches to pterygopalatine fossa tumors

BACKGROUND

The pterygopalatine fossa (PPF) is a difficult area to access, as it has been traditionally treated by external approaches. The development of endoscopic transnasal approaches enables surgeons to reach this region through a minimally invasive route, reducing the associated morbidity.

METHODS

We conducted a retrospective review of patients with benign and malignant tumors arising in or extending to the PPF, treated from 2000 to 2013 at a single institute, using endoscopic transnasal transmaxillary approaches.

RESULTS

Thirty-seven consecutive patients with benign (27 cases) and malignant (10 cases) tumors were treated with curative intent. Radical resection was achieved in 36 of 37 patients. No major complications were observed. No local recurrences were observed, with a median follow-up of 38.5 months for malignancies and 60 months for benign tumors.

CONCLUSION

The endoscopic transnasal approaches are safe and feasible techniques for the radical resection of selected tumors involving the PPF and should be tailored according to the biology and extension of the lesion. © 2015 Wiley Periodicals, Inc. Head Neck 38: E214-E220, 2016.

Combined endonasal and sublabial endoscopic transmaxillary approach to the pterygopalatine fossa and orbital apex

BACKGROUND

The pterygopalatine fossa (PPF) and inferomedial orbital apex are difficult regions for open neurosurgical access. The traditional extensive anterior approach (transfacial or transmandibular) and lateral/posterolateral (transcranial) approach were used to access the PPF. The combined endonasal and sublabial transmaxillary approach is a less invasive access route for these lesions. In this study, we present the technical and clinical details of our experience with the combined endoscopic endonasal and transmaxillary approach.

METHODS

A retrospective analysis of our patients operated on using a combined endoscopic endonasal and transmaxillary approach was done. The preoperative, intraoperative and postoperative images and all the clinical data were evaluated. The accessibility to the area and extent of surgical resection were reviewed. The surgery-related complications and postoperative morbidities were analyzed. The main items of interest were the exposure of the target area and possibility for safe removal.

RESULTS

Five patients with pathologies located in the area of the PPF and orbital apex were operated on using the combined endoscopic sublabial and endonasal transmaxillary approach. The technique provided sufficient exposure of the area and allowed for safe removal of the preoperatively determined target in all of the patients. One patient developed dry eye and a neurotrophic corneal ulcer, and another patient developed temporary postoperative facial numbness. In the follow-up, only one patient with skull base chordoma had an asymptomatic tumor regrowth. The other patients had no recurrence or regrowth.

CONCLUSIONS

The combined endoscopic sublabial and endonasal transmaxillary approach is a safe and effective method for resection of lesions in the PPF and inferomedial orbital apex.

Sphenopalatine foramen: endoscopic approach with bony landmarks

OBJECTIVE

To establish whether nasal bony landmarks on computed tomography could be utilised reliably in endoscopic approaches to the sphenopalatine foramen.

METHODS

A prospective analysis of 102 consecutive helical computed tomography scans of the paranasal sinuses was carried out by 2 senior ENT surgeons. Distances from the sphenopalatine foramen to endoscopically palpable bony landmarks were measured.

RESULTS

There were a total of 102 patients (45 females and 57 males), with a mean age of 62 years. The mean distance from the posterior fontanelle to the sphenopalatine foramen was 14.1 mm (standard deviation = 2.13). The average vertical distance of the sphenopalatine foramen opening from the bony attachment of the inferior turbinate was 14.13 mm. There were no statistically significant differences between any of these measurements (foramen width p-value = 0.714, distance from fontanelle p-value = 0.43 and distance from inferior turbinate p-value = 0.48).

CONCLUSION

Determination of reliable bony landmarks is clinically useful in endoscopic surgery and can aid identification of the sphenopalatine foramen. The inferior turbinate concha and posterior fontanelle may be used as reliable computed tomography landmarks for endoscopic approaches to the sphenopalatine foramen.

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.

Extended endoscopic endonasal transclival approach to the ventrolateral brainstem and related cisternal spaces: anatomical study

Advances in endoscopic endonasal skull base surgery have led to the development of new routes to areas beyond the midline skull base. Recently, feasible surgical corridors to the lateral skull base have been described. The aim of this study was to describe the anatomical exposure of the ventrolateral brainstem and posterior fossa through an extended endoscopic endonasal transclival transpetrosal and transcondylar approach. Six human heads were used for the dissection process. The arterial and venous systems were injected with red- and blue-colored latex, respectively. A pre- and postoperative computed tomography (CT) scan was carried out on every head. The endoscopic endonasal transclival approach was extended through an anterior petrosectomy and a medial condylectomy. A three-dimensional model of the approach was reconstructed, using a dedicated software, from the overlapping of the pre- and post-dissection CT imaging of the specimen. An extended endoscopic transclival approach allows to gain access through an extradural anterior petrosectomy and medial condylectomy to the anterolateral surface of the brainstem and the posterior fossa. Two main intradural anatomical corridors can be described: first, between the V cranial nerve in the prepontine cistern and the VII-VIII cranial nerves in the cerebellopontine and cerebellomedullary cistern; second, between the VII-VIII cranial nerves and the IX cranial nerve, in the premedullary cistern. Extending the transclival endoscopic approach by performing an extradural anterior petrosectomy and a medial condylectomy provides a safe and wide exposure of the anterolateral brainstem with feasible surgical corridors around the main neurovascular structures.

Endoscopic and Three-Dimensional Radiographic Imaging of the Pterygopalatine and Infratemporal Fossae

Objectives:

We sought to define the surgical endoscopic anatomy of the pterygopalatine fossa (PPF) and infratemporal fossa (ITF) through endoscopic cadaver dissections and radiographic imaging analysis.

Methods:

Eleven fresh cadavers were submitted to computed tomography (CT) and endoscopic dissection. We used 3-dimensional (3-D) CT reconstruction and endoscopic video imaging for analysis of the bony and soft tissue landmarks. One fixed cadaver head was grossly dissected to confirm the endoscopic anatomic findings.

Results:

The CT and 3-D CT reconstruction measurements between the pterygoid canal and the foramen rotundum averaged 4.36 mm and 5.09 mm, respectively. An osseous ridge (pterygoid ridge) was identified on the anterior face of the pterygoid process as a novel identifiable anatomic landmark in all of the specimens. The average length of the pterygoid ridge on 3-D CT reconstruction was 7.84 mm. The internal maxillary artery entered the PPF posteromedial to the temporalis tendon and anterolateral to the lateral pterygoid muscle. The average distance from the anterior edge of the lateral pterygoid plate to the foramen ovale was 17.1 mm.

Conclusions:

The pterygoid ridge is a novel and reliable osseous landmark that could assist surgeons during endoscopic surgery on the PPF and ITF. The neurovascular and muscular anatomic relationships were characterized for both the PPF and the ITF.

Endoscopic endonasal approach to the infraorbital nerve with nasolacrimal duct preservation

Objectives Infraorbital nerve (ION) decompression, excision to remove intrinsic tumors, and resection with oncological margins in malignancies with perineural invasion or dissemination are usually accomplished with an open approach. The objective is to describe the surgical anatomy, technique, and indications of the endonasal endoscopic approach (EEA) to the ION with nasolacrimal duct preservation. Design Eleven sides of formalin-fixed specimens were dissected. An anterior maxillary antrostomy was performed. The length of the ION prominence within the sinus and anatomic features of the covering bone were studied. A 45-degree endoscope visualized the infraorbital prominence endonasally. An angled dissector and dural blade allowed for dissection and resection of the ION ipsilaterally and contralaterally. Results The bone features of the ION prominence allowed for ipsilateral dissection in 10 out of 11 sides. In one case with the ION surrounded by thick cortical bone, the dissection could only be started by drilling contralaterally. The 45-degree endoscope visualized 92.2% and 100% of the length of the nerve using the ipsilateral and contralateral nostrils, respectively. Ipsilaterally, 83% of its length was resected, and 96.3% was resected contralaterally. Conclusion The ION can be approached using an ipsilateral EEA with nasolacrimal duct preservation in most cases. The contralateral approach provides a wider angle to access the ION. This technique is primarily indicated in cases where the EEA can be used for tumor resection and oncological margins within the ION.

Combined transoral robotic surgery and endoscopic endonasal approach for the resection of extensive malignancies of the skull base

BACKGROUND

Oncologic resection of the clivus, nasopharynx, craniovertebral junction, and infratemporal fossa is a challenging endeavor because of their complex and protected anatomy. Our goals were to design a cadaveric model and identify advantages and limitations of combining the transoral robotic surgery (TORS) and endoscopic endonasal approach (EEA) techniques.

METHODS

Cadaveric specimens were dissected using a da Vinci surgical robot and endoscopic endonasal instruments in a fashion that mimicked our operating room environment. We then applied these techniques clinically.

RESULTS

EEA was performed to provide a detailed dissection of the infratemporal fossa, nasopharynx, posterior skull base (clivus), and craniovertebral junction. Using TORS, we dissected the parapharyngeal space, infratemporal fossa, and nasopharynx below the eustachian tube, which represented a transition zone that delineated the most effective resection field of each approach.

CONCLUSIONS

TORS and EEA seem to be complementary techniques; thus, their combined use seems advantageous for selected advanced tumors in these complex areas.

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

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

Endoscopic endonasal transturbinate approach to the pterygopalatine fossa in the management of juvenile nasopharyngeal angiofibromas

Pterygopalatine fossa (PPF) is a difficult-to-access anatomic area located behind the posterior wall of the maxillary sinus. Juvenile nasopharyngeal angiofibroma (JNA) often affects this area, and the management of feeding artery to the tumor is important in the surgery. Endoscopic endonasal approach to the PPF without endangering all other nasal structures is useful in the management of JNA. We describe a new approach to the PPF, endoscopic transturbinate approach, which is effective in the management of JNA. Submucous inferior turbinoplasty was performed, and sphenopalatine artery, the feeder to the tumor, was identified at the sphenopalatine foramen. The posterior wall of maxillary sinus was removed. Internal maxillary artery was identified in the PPF and was ligated with a hemoclip. The tumor in the PPF was pushed into the nasal cavity. These procedures were all performed via submucous turbinate tunnel. Then, the tumor was successfully removed in en bloc from the nasal cavity by transnasal approach without ethmoidectomy. This approach improves accessibility and visualization in the PPF and potential to reduce intraoperative bleeding due to ligation of the feeder safely without touching the tumor. Endoscopic transturbinate approach is effective in the management of early stage of JNA.

Three-dimensional computed tomography analysis to help define an endoscopic endonasal approach of the pterygopalatine fossa

BACKGROUND

The pterygopalatine fossa (PPF) can be entered endoscopically, but the endoscopic landmarks to localize the bony structures in the PPF are not well described. This study aimed to investigate the anatomy of the sphenopalatine foramen (SPF), vidian canal (VC), and foramen rotundum (FR) with regard to an endoscopic endonasal approach to the PPF using three-dimensional reconstruction of computed tomography (CT) scans.

METHODS

The CT scans of 98 patients were retrospectively evaluated. The morphology of the SPF, VC, and FR as well as the spatial relationship between the SPF and VC were measured on a three-dimensional model.

RESULTS

The mean diameters of the SPF, VC, and FR were 5.3 ± 1.3 mm, 2.4 ± 0.7 mm, and 2.8 ± 0.5 mm, respectively. The mean distance between the VC and posteroinferior margin of SPF was 3.8 ± 1.0 mm. The mean vertical and horizontal distances on the surface plane of sphenoid bone between the VC and FR were 5.8 ± 1.9 mm and 8.5 ± 1.9 mm, respectively. The whole or partial margin of the VC was above the inferior margin of the SPF in 92% (180/196) of the VC and lateral to the posterior margin of the SPF in 98% (195/196) of the VC. The distance between the VC and SPF had a positive correlation with the distances between the VC and FR.

CONCLUSION

The endoscopic endonasal approach to the PPF will be performed with greater accuracy and safety through comprehension of the spatial relationships between the SPF, VC, and FR.

The transnasal approach to the skull base. From sinus surgery to skull base surgery

The indications for endonasal endoscopic approaches to diseases of the skull base and its adjacent structures have expanded considerably during the last decades. This is not only due to improved technical possibilities such as intraoperative navigation, the development of specialized instruments, and the compilation of anatomical studies from the endoscopic perspective but also related to the accumulating experience with endoscopic procedures of the skull base by multidisciplinary centers. Endoscopic endonasal operations permit new approaches to deeply seated lesions and are characterized by a reduced manipulation of neurovascular structures and brain parenchyma while at the same time providing improved visualization. They reduce the trauma caused by the approach, avoid skin incisions and minimize the surgical morbidity. Transnasal endoscopic procedures for the closure of small and large skull base defects have proven to be reliable and more successful than operations with craniotomies. The development of new local and regional vascularized flaps like the Hadad-flap have contributed to this. These reconstructive techniques are furthermore effectively utilized in tumor surgery in this region. This review delineates the classification of expanded endonasal approaches in detail. They provide access to lesions of the anterior, middle and partly also to the posterior cranial fossa. Successful management of these complex procedures requires a close interdisciplinary collaboration as well as continuous education and training of all team members.

Endoscopic skull base surgery: a comprehensive comparison with open transcranial approaches

Little data exists comparing endoscopic endonasal approaches to pathology of the anterior skull base with more traditional transcranial and transsphenoidal microscopic approaches. In order to more fully characterize the role of endoscopy in the management of pathology of the anterior cranial base, we conducted a systematic review of case series and case reports documenting surgical and clinical outcomes. We found that for craniopharyngiomas, clival chordomas, esthesioneuroblastomas and giant pituitary adenomas, the endonasal endoscopic approach can result in equivalent or higher rates of gross total resection than open approaches. For meningiomas, however, open transcranial approaches are still able to achieve higher rates of total resection. CSF leak rates are higher for patients undergoing endoscopic surgery for meningiomas and craniopharyngiomas, but not for chordomas, esthesioneuroblastomas or giant pituitary adenomas. In certain patients, the endonasal endoscopic approach may be a safe and effective alternative for the treatment of a wide variety of skull base pathology, particularly those with small midline tumours.

Expanded endonasal endoscopic approach for resection of a skull base low-grade smooth muscle neoplasm

Benign smooth muscle tumors rarely occur in the head and neck and, to the best of our knowledge, have not been reported in the pterygopalatine fossa. In this report, we describe a 15-year-old adolescent who presented with facial pain and was found to have a large skull base tumor centered in the pterygopalatine fossa. The patient underwent an expanded endonasal endoscopic approach for complete resection of this lesion with resolution of his symptoms. Pathology revealed a well-differentiated smooth muscle neoplasm consistent with a leiomyoma. This case adds to the growing body of literature supporting a role for endoscopic procedures in the treatment of skull base pathologies in pediatric patients.

Endoscopic endonasal skull base surgery: analysis of complications in the authors' initial 800 patients

Object

The development of endoscopic endonasal approaches, albeit in the early stages, represents part of the continuous evolution of skull base surgery. During this early period, it is important to determine the safety of these approaches by analyzing surgical complications to identify and eliminate their causes.

Methods

The authors reviewed all perioperative complications associated with endoscopic endonasal skull base surgeries performed between July 1998 and June 2007 at the University of Pittsburgh Medical Center.

Results

This study includes the data for the authors' first 800 patients, comprising 399 male (49.9%) and 401 female (50.1%) patients with a mean age of 49.21 years (range 3–96 years). Pituitary adenomas (39.1%) and meningiomas (11.8%) were the 2 most common pathologies. A postoperative CSF leak represented the most common complication, occurring in 15.9% of the patients. All patients with a postoperative CSF leak were successfully treated with a lumbar drain and/or another endoscopic approach, except for 1 patient who required a transcranial repair. The incidence of postoperative CSF leaks decreased significantly with the adoption of vascularized tissue for reconstruction of the skull base (< 6%). Transient neurological deficits occurred in 20 patients (2.5%) and permanent neurological deficits in 14 patients (1.8%). Intracranial infection and systemic complications were encountered and successfully treated in 13 (1.6%) and 17 (2.1%) patients, respectively. Seven patients died during the 30-day perioperative period, 6 of systemic illness and 1 of infection (overall mortality 0.9%).

Conclusions

Endoscopic endonasal skull base surgery provides a viable median corridor based on anatomical landmarks and is customized according to the specific pathological process. This corridor should be considered as the sole access or may be combined with traditional approaches. With the incremental acquisition of skills and experience, endoscopic endonasal approaches have an acceptable safety profile in select patients presenting with various skull base pathologies.

Endoscopic surgical treatment of neurogenic tumor in pterygopalatine and infratemporal fossae via extended medial maxillectomy

CONCLUSION

The endoscopic extended medial maxillectomy approach for the management of lesions of the pterygopalatine and infratemporal fossa provides excellent exposure and results with good hemostasis and low morbidity. This approach is a viable alternative to the open approaches to these areas.

OBJECTIVES

To describe an endoscopic extended medial maxillectomy approach for the treatment of nonmalignant tumors in the pterygopalatine and infratemporal fossa.

METHODS

From January 2004 to June 2007, five patients who had tumors in the pterygopalatine fossa and/or infratemporal fossa, and underwent surgical resection of the tumors with the endoscopic extended medial maxillectomy approach, were reviewed regarding demographics, preoperative images, tumor cell type, surgical techniques, and outcomes.

RESULTS

Five patients underwent the procedure mentioned above; three females and two males with a mean age of 38 and a range of 21-58 years. All patients had adequate exposure and total tumor resection with the endoscopic extended medial maxillectomy approach. None of the patients required an external approach for tumor extirpation. There were no major postoperative complications. No evidence of tumor recurrence was noted after follow-up for 12-78 months.

Fully endoscopic transnasal approach to the jugular foramen: anatomic study and clinical considerations

BACKGROUND AND IMPORTANCE

To describe a transnasal endoscopic route to the jugular foramen and the endoscopic anatomy of the infratemporal fossa.

CLINICAL PRESENTATION

Endoscopic transnasal dissection of the infratemporal fossa was performed in 3 injected fresh heads (1 head only in arteries and 2 heads in arteries and veins). Two other double-injected specimens were dissected externally (2 of them side laterally and 1 anteriorly) to compare the different views and better understand the 3-dimensionality of the region.Detailed endoscopic anatomy of the infratemporal fossa was clearly observed. The realization of a septal and posterior maxillary window allows surgeons to gain space to the jugular foramen. The ability to manage the vessels, especially the veins, and identify the muscles is mandatory. The fundamental role of the vidian canal in targeting the anterior genu of the internal carotid artery is confirmed. The role of the maxillary and mandibular branches of the trigeminal nerve and the eustachian tube in this kind of approach is critical.

CONCLUSION

A fully transnasal endoscopic route to the jugular foramen is feasible. The most important landmark for this kind of approach is the eustachian tube.

The endoscopic, endonasal, transmaxillary transpterygoid approach to the pterygopalatine fossa, infratemporal fossa, petrous apex, and the Meckel cave

Object

In this paper the authors' goal was to present their clinical experience with lesions of the pterygopalatine fossa, infratemporal fossa, lateral sphenoid sinus, cavernous sinus, petrous apex, and Meckel cave using simple and extended endoscopic transpterygoid approaches to the lateral skull base.

Methods

Simple and expanded endoscopic transpterygoid approaches were performed in a series of 13 patients with varying pathology that included lateral sphenoid sinus encephaloceles, benign and malignant sinonasal tumors, and lesions of neural origin.

Results

A gross-total resection was achieved in 5 of 9 patients, while a subtotal resection for tissue diagnosis and cytoreduction prior to further adjuvant treatment was performed in the remaining patients. Sphenoid sinus encephaloceles were successfully repaired via a transpterygoid approach in all 4 patients. The skull base defect was reconstructed using a multilayered closure. One patient developed a postoperative CSF leak, which was successfully treated conservatively. The mean follow-up time was 16 months. Five patients complained of recurrent sinusitis. One patient experienced xerophthalmia and palate numbness. Three patients had died by the time of this report. Two patients died of unrelated causes. The third patient died of progression of an aggressive pterygopalatine osteosarcoma despite undergoing cytoreductive surgery and adjuvant chemotherapy.

Conclusions

An endoscopic transpterygoid approach is a minimally invasive endoscopic approach for lesions located or extending to the pterygopalatine fossa, infratemporal fossa, petrous apex, Meckel cave, and other regions of the paramedian skull base.

Endoscopic nasopharyngectomy for salvage in nasopharyngeal carcinoma: a novel anatomic orientation

OBJECTIVES/HYPOTHESIS

Nasopharyngectomy for residual/recurrent nasopharyngeal carcinoma (NPC) using an endoscopic technique is less invasive than traditional methods. Our objective was to identify the important anatomic landmarks so that the endoscopic surgeon can avoid injury to the internal carotid artery and perform a nasopharyngectomy safely.

STUDY DESIGN

Anatomical study.

METHODS

Transnasal endoscopic dissection was carried out on three fresh adult cadaver specimens (six sides) after arterial latex injection. Measurements were made in 50 adult skulls (100 sides), detailing the distances between orienting critical landmarks and the internal carotid canal (external aperture).

RESULTS

Adequate exposure for endoscopic nasopharyngectomy is available by removing portions of the inferior turbinate, nasal septum, and medial pterygoid plate. Anatomy of the operative field (endoscopic view) is described. Orientating topical landmarks include: posterior portions of the inferior turbinate and nasal septum, fossa of Rosenmuller, and the torus tubarius. The deep landmarks include: medial pterygoid plate-posterior margin at the skull base, eustachian tube isthmus, foramen lacerum, and the longus capitis. All topical and deep landmarks were identified from the endoscopic point of view and their distances to the internal carotid canal (external aperture) were measured.

CONCLUSIONS

This anatomic study provides novel orienting landmarks for endoscopic nasopharyngectomy. Surgeons can efficiently and safely deal with residual and/or recurrent NPC endoscopically.

Endoscopic transnasal resection of ectopic esthesioneuroblastoma in the pterygopalatine fossa: technical case report

OBJECTIVE

Esthesioneuroblastoma is a rare, malignant neoplasm arising from the olfactory neuroepithelium in the upper nasal cavity. Even more rare is ectopic esthesioneuroblastoma developing from the region outside the olfactory epithelium. In addition, tumors occurring in the pterygopalatine fossa (PPF) are uncommon, and the endoscopic transnasal approach for the resection of malignant tumors in this region is also uncommon.

CLINICAL PRESENTATION

We describe an esthesioneuroblastoma arising from the left maxillary sinus and PPF. The tumor was resected using the endoscopic transnasal approach, followed by treatment with radiotherapy. The patient showed no evidence of recurrence 12 months postoperatively.

TECHNIQUE

The endoscopic transnasal approach could be successfully used for the complete removal of malignant tumors in the PPF.

CONCLUSION

The PPF is an anatomic area that is difficult to access. The endoscopic transnasal approach improves access and visualization; it also has the potential to reduce complications compared with the open approach. The endoscopic transnasal approach might become the treatment of choice for malignant tumors in the PPF.

Three-dimensional and 2-dimensional endoscopic exposure of midline cranial base targets using expanded endonasal and transcranial approaches

OBJECTIVE

Endoscopic endonasal approaches provide an access method to the midline cranial base. To integrate these approaches into neurosurgical practice, the extent of their anatomic exposure must be compared with that provided by more traditional transcranial approaches.

METHODS

Ten fresh cadaver heads were studied. Both endonasal and transcranial approaches to the midline cranial base were performed. The midline cranial base was divided into several areas, and the relative exposure provided by each approach was described and presented in both 2-dimensional and 3-dimensional images. Limitations and advantages of each approach are discussed.

RESULTS

The endonasal approaches achieved a direct and wide exposure of the midline extracranial and intracranial cranial base anatomy. The main lateral limitations of the endonasal approaches were the optic nerves, lateral cavernous sinus, vidian nerve, internal carotid artery, abducens nerve in Dorello's canal, jugular tubercle, and hypoglossal canals. Limitations of the transcranial approaches were the neurovascular structures which lie in the operative corridor and create narrow working spaces.

CONCLUSION

The endonasal approaches achieve a direct and wide exposure of the midline cranial base bilaterally. Lateral exposure, beyond the cranial nerves and carotid artery, are challenging. Transcranial approaches are limited by the narrow corridors provided by the cranial nerves, and they do not visualize the contralateral paramedian cranial base very well. Three-dimensional endoscopes augment the spatial orientation and may improve patient safety and the learning curve for endoscopic approaches to the midline cranial base.

Microsurgical and endoscopic anatomy of the vidian canal

OBJECTIVE

The vidian canal, the conduit through the sphenoid bone for the vidian nerve and artery, has become an important landmark in surgical approaches to the cranial base. The objective of this study was to examine the anatomic features of the vidian canal, nerve, and artery, as well as the clinical implications of our findings.

METHODS

Ten adult cadaveric specimens and 10 dried skulls provided 40 vidian canals for examination with x 3 to x 20 magnification and the endoscope.

RESULTS

The paired vidian canals are located in the skull base along the line of fusion of the pterygoid process and body of the sphenoid bone. The canal opens anteriorly into the medial part of the pterygopalatine fossa and posteriorly at the upper part of the anterolateral edge of the foramen lacerum. The vidian nerve, when followed posteriorly, reaches the lateral surface of the anterior genu of the petrous carotid and the anteromedial part of the cavernous sinus where the nerve is continuous with the greater petrosal nerve. The bone surrounding the upper part of 12 of 20 vidian canals protruded into the floor of the sphenoid sinus and one canal had a bony dehiscence that exposed its contents under the sinus mucosa. Nine petrous carotid arteries (45%) gave rise to a vidian artery, all of which anastomosed with the vidian branch of the maxillary artery in the vidian canal or pterygopalatine fossa. The vidian canal can be exposed by opening the floor of the sphenoid sinus, the posterior wall of the maxillary, the posterior part of the lateral wall of the nasal cavity, and the medial part of the floor of the middle fossa.

CONCLUSION

The vidian canal and nerve are important landmarks in accessing the anterior genu of the petrous carotid, anteromedial part of the cavernous sinus, and petrous apex.

The front door to meckel's cave: an anteromedial corridor via expanded endoscopic endonasal approach- technical considerations and clinical series

OBJECTIVE

Tumors within Meckel's cave are challenging and often require complex approaches. In this report, an expanded endoscopic endonasal approach is reported as a substitute for or complement to other surgical options for the treatment of various tumors within this region.

METHODS

A database of more than 900 patients who underwent the expanded endoscopic endonasal approach at the University of Pittsburgh Medical Center from 1998 to March of 2008 were reviewed. From these, only patients who had an endoscopic endonasal approach to Meckel's cave were considered. The technique uses the maxillary sinus and the pterygopalatine fossa as part of the working corridor. Infraorbital/V2 and the vidian neurovascular bundles are used as surgical landmarks. The quadrangular space is opened, which is bound by the internal carotid artery medially and inferiorly, V2 laterally, and the abducens nerve superiorly. This offers direct access to the anteroinferomedial segment of Meckel's cave, which can be extended through the petrous bone to reach the cerebellopontine angle.

RESULTS

Forty patients underwent an endoscopic endonasal approach to Meckel's cave. The most frequent abnormalities encountered were adenoid cystic carcinoma, meningioma, and schwannomas. Meckel's cave and surrounding structures were accessed adequately in all patients. Five patients developed a new facial numbness in at least 1 segment of the trigeminal nerve, but the deficit was permanent in only 2. Two patients had a transient VIth cranial nerve palsy. Nine patients (30%) showed improvement of preoperative deficits on Cranial Nerves III to VI.

CONCLUSION

In selected patients, the expanded endoscopic endonasal approach to the quadrangular space provides adequate exposure of Meckel's cave and its vicinity, with low morbidity.

Blood supply to the intracavernous cranial nerves: comparison of the endoscopic and microsurgical perspectives

OBJECTIVE

To provide a comparative description of the endoscopic and microsurgical anatomic features of the blood supply to the cranial nerves in the lateral wall of the cavernous sinus.

METHODS

Twenty-four cavernous sinuses were dissected in 12 adult cadaveric heads. Endoscopic observations were made with 0- and 45-degree, 4-mm rod-lens endoscopes. The lateral wall of the cavernous sinus was exposed through an endonasal transsphenoidal approach. The microsurgical observations were performed with a surgical microscope with possible magnification ranging from 4x to 40x through a lateral transcranial approach. Neurovascular relationships in the lateral wall of the cavernous sinus were noted, and the endoscopic and microsurgical perspectives were compared.

RESULTS

The neurovascular relationships in the lateral wall of the cavernous sinus that are visible by the endonasal transsphenoidal approach but not visible by the transcranial microsurgical approach are as follows: between the oculomotor nerve and the tentorial artery, between the distal segment of the trochlear nerve and the tentorial artery, between the ophthalmic nerve and the inferolateral trunk, and between the abducens nerve and the inferolateral trunk. The neurovascular relationships visible by the transcranial microsurgical approach but not visible by the transsphenoidal endoscopic approach are as follows: between the oculomotor nerve and the superoproximal artery, when present, and between the proximal segment of the trochlear nerve and the superoproximal artery.

CONCLUSION

Incorporating the endoscopic and microsurgical perspectives ensures a better understanding of the neurovascular relationships in the cavernous sinus lateral wall. This information could be relevant for preservation of the blood supply to the nerves during surgery in or around the cavernous sinus.

Endoscopic cranial base surgery: classification of operative approaches

OBJECTIVE

Endoscopic cranial base surgery is a minimal access, maximally aggressive alternative to traditional transfacial, transcranial, or combined open cranial base approaches. Previous descriptions of endoscopic approaches have used varying terminology, which can be confusing to the new practitioner. Indications for surgery are not well defined. Our objective was to create a comprehensive classification system of the various approaches and describe their indications with case examples.

METHODS

We prospectively compiled a comprehensive database of our endonasal endoscopic operations, detailing the nasal sinus transgressed, the cranial base approach, and the intracranial target for the first 150 consecutive cases performed at our institution. All cases were performed collaboratively by a neurosurgeon and an otolaryngologist.

RESULTS

We categorized the endonasal endoscopic cranial base operations into four nasal corridors, nine cranial base approaches, and 13 intracranial targets. Each of the various approaches is described in detail and illustrated with case examples. Pathology encountered included pituitary tumor (50%), meningocele/encephalocele (14%), craniopharyngioma and Rathke cleft cyst (10%), meningioma (8%), chordoma (5%), esthesioneuroblastoma (2%), and other (11%).

CONCLUSION

Endonasal endoscopic cranial base surgery is a minimal access, maximally invasive alternative to open transcranial cranial base approaches for specific indications. A clear understanding of the possible approaches is facilitated by an awareness of the nasal corridors and intracranial targets.

Endoscopic skull base surgery

Endoscopic skull base surgery has undergone rapid advancement in the past decade moving from pituitary surgery to suprasellar lesions and now to a myriad of lesions extending from the cribriform plate to C2 and laterally out to the infratemporal fossa and petrous apex. Evolution of several technological advances as well as advances in understanding of endoscopic anatomy and the development of surgical techniques both in resection and reconstruction have fostered this capability. Management of benign disease via endoscopic methods is largely accepted now but more data is needed before the controversy on the role of endoscopic management of malignant disease is decided. Continued advances in surgical technique, navigation systems, endoscopic imaging technology, and robotics assure continued brisk evolution in this expanding field.