Neurovascular Surgical Keys Related to Sphenoid Window: Radiologic Study of Egyptian's Sphenoid

OBJECTIVES

The anatomic variations of the sphenoid sinus and its relation to the surrounding neurovascular structures are a subject of interest. The purpose of this study was to radiologically assess the frequency of protrusion/dehiscence of key neurovascular landmarks surrounding the Egyptians' sphenoid.

METHODS

This is a cross-sectional descriptive study of sinonasal computed tomography of the sphenoid sinus in 500 adult Egyptians, conducted at Mansoura University Hospitals; Egypt, over a period of 1 year. Two archives were used for collecting the data; the hard archive and the electronic archive. Variables of interest included the extent of sphenoid sinus pneumatization; intersphenoid septation pattern; protrusion/dehiscence of the internal carotid artery, optic nerve, maxillary nerve, and vidian nerve; and detection of the Onodi cell.

RESULTS

Population of this study included 265 women and 235 men. Their ages ranged from 18-68 years. The bilateral sellar-type pneumatization was shown as the most common pneumatization type (96.8%). Pneumatizations of the pterygoid process, anterior clinoid process, and greater wing of the sphenoid were identified in 9.3%, 8.9%, and 31.8% consequently. A single intersphenoid septum was detected in 85.2%, whereas multiple intersphenoid septums were noted in 11.6%. Protrusion of the internal carotid artery, optic nerve, vidian nerve, and maxillary nerve was recorded in 8.5%, 9.1%, 6.6%, and 3.4% consequently, while dehiscence was reported in 7.2%, 15%, 11.9%, and 4.2% consequently as well. Onodi cell was recognized in 18%.

CONCLUSIONS

This radiologic study highlights significant variations of surgically important anatomic structures related to the sphenoid sinus in Egyptians.

Quantitative Computer-Aided Computed Tomography Analysis of Sphenoid Sinus Anatomical Relationships

Background

This study describes a novel computer-generated anatomic symmetry plane as a framework for the quantitative description of sphenoid sinus anatomy. The aim of this study was to (1) determine relationships and distances between a midline sphenoid reference point (called the central sphenoid point [CSP]) and lateral sphenoid wall structures and (2) assess the incidence of anterior clinoid process (ACP) pneumatization and pterygoid recess (PR) pneumatization.

Methods

Axial computed tomography (CT) scans (1-mm slice thickness) were obtained on a VolumeZoom CT scanner (Siemens Medical, Erlangen, Germany). Mathematically derived anatomic symmetry planes were created using custom postprocessing software. A standardized review of each CT scan using surgical planning software (CBYON Suite version 2.6; CBYON, Mountain View, CA) was performed. The CSP was defined as a reference point in the midline sagittal plane at the intersection of the vertical sellar face and the horizontal sellar floor.

Results

A total of 128 sides in 64 cadaveric specimens were available for review. The incidences of ACP pneumatization and PR pneumatization were 23.4 and 37.5%. The mean distances from the CSP to the left optic canal midpoint, the left ACP entrance point, and the left PR lateral wall were 17.2, 15.6, and 27.6 mm, respectively. The corresponding distances from the CSP on the right side were 17.3, 15.8, and 28.0 mm, respectively. Measurements from the maxillary spine to the optic canal midpoint, ACP entrance point, and PR lateral wall on each side were performed also.

Conclusion

This approach provides both quantitative and qualitative understanding of sphenoid osteology and may be coupled with intraoperative surgical navigation to reduce the risks of sphenoid surgery. Both PR and ACP pneumatization are surprisingly common. Because the CSP-derived relationships may be referenced during endoscopic surgical navigation, they may provide greater clinical utility than traditional alternatives. This paradigm may facilitate a greater understanding of sphenoid anatomy and enhance surgical safety and precision.

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.

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.

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.

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 anatomy of the pterygopalatine fossa and the transpterygoid approach: development of a surgical instruction model

INTRODUCTION

The pterygopalatine fossa (PPF) is a narrow space located between the posterior wall of the antrum and the pterygoid plates. Surgical access to the PPF is difficult because of its protected position and its complex neurovascular anatomy. Endonasal approaches using rod lens endoscopes, however, provide better visualization of this area and are associated with less morbidity than external approaches. Our aim was to develop a simple anatomical model using cadaveric specimens injected with intravascular colored silicone to demonstrate the endoscopic anatomy of the PPF. This model could be used for surgical instruction of the transpterygoid approach.

METHODS

We dissected six PPF in three cadaveric specimens prepared with intravascular injection of colored material using two different injection techniques. An endoscopic endonasal approach, including a wide nasoantral window and removal of the posterior antrum wall, provided access to the PPF.

RESULTS

We produced our best anatomical model injecting colored silicone via the common carotid artery. We found that, using an endoscopic approach, a retrograde dissection of the sphenopalatine artery helped to identify the internal maxillary artery (IMA) and its branches. Neural structures were identified deeper to the vascular elements. Notable anatomical landmarks for the endoscopic surgeon are the vidian nerve and its canal that leads to the petrous portion of the internal carotid artery (ICA), and the foramen rotundum, and V2 that leads to Meckel's cave in the middle cranial fossa. These two nerves, vidian and V2, are separated by a pyramidal shaped bone and its apex marks the ICA.

CONCLUSION

Our anatomical model provides the means to learn the endoscopic anatomy of the PPF and may be used for the simulation of surgical techniques. An endoscopic endonasal approach provides adequate exposure to all anatomical structures within the PPF. These structures may be used as landmarks to identify and control deeper neurovascular structures. The significance is that an anatomical model facilitates learning the surgical anatomy and the acquisition of surgical skills. A dissection superficial to the vascular structures preserves the neural elements. These nerves and their bony foramina, such as the vidian nerve and V2, are critical anatomical landmarks to identify and control the ICA at the skull base.

Endoscopic anatomy of the pterygopalatine fossa

BACKGROUND

The pterygopalatine fossa can be involved with a variety of infectious and neoplastic processes. This region can be entered endoscopically, but endoscopic landmarks to localize the neurovascular structures in the pterygopalatine fossa have not yet been reported.

OBJECTIVES

The purpose of this study is to describe the location of the neurovascular structures in the pterygopalatine fossa in relation to consistent intranasal landmarks.

METHODS

Endoscopic dissections of cadaveric heads were performed. The locations of neurovascular structures in the region were defined.

RESULTS

The sphenopalatine foramen (SPF) served as the primary intranasal landmark to the pterygopalatine fossa (PPF). Mean distances from the SPF were measured with the following results: SPF to sphenopalatine ganglion (SPG), 4 mm medially and 6 mm laterally; SPF to foramen rotundum (FR), 7 mm; and SPF to vidian canal (VC), 2 mm. The internal maxillary artery followed an irregular and inconsistent course, making it difficult to define a reliable landmark for its location in the fossa.

CONCLUSION

Entering the PPF inferior to the horizontal plane of the SPF along a vertical line drawn inferiorly from the infraorbital canal will avoid injury to the major neural structures in the fossa. Because of the inconsistent course and location of the internal maxillary artery, this structure may be at risk no matter where the fossa is entered. These landmarks will allow the surgeon to enter the PPF with more accuracy and less patient morbidity.

Combined endoscopic transmaxillary-transnasal approach to the pterygoid region, lateral sphenoid sinus, and retrobulbar orbit

OBJECTIVES

The sublabial transmaxillary approach to the pterygoid region was a popular one during the Caldwell-Luc, pre-endoscopic era. It was the procedure of choice for management of lesions of the pterygopalatine space, for internal maxillary artery ligation, and for vidian neurectomy. With the introduction of endoscopic instrumentation and techniques, the Caldwell-Luc procedure is rarely performed today. Also, because vidian neurectomy is performed less frequently, and because internal maxillary artery ligation for severe epistaxis has been replaced with transnasal endoscopic sphenopalatine artery ligation, the sublabial transmaxillary route is rarely used. We have found that combining the use of endoscopes via the sublabial approach and the transnasal endoscopic approach is very helpful for management of extreme lateral lesions of the sphenoid sinus, as well as the pterygoid region and the posterior orbit.

METHODS

The records of patients who underwent a combined endoscopic transmaxillary-transnasal approach between 1994 and 2002 were reviewed. Indications for the procedure included extreme lateral sphenoid and pterygoid encephalocele (3 patients), pterygoid mucocele (2 patients), orbital apex lesion (2 patients), and pterygopalatine tumor (2 patients).

RESULTS

Nine patients underwent the above-mentioned procedure. Wide and comfortable exposure of the involved region was achieved in all cases. Compared with the transnasal approach, the working distance, working comfort, and maneuverability of instruments were significantly enhanced. There were no major complications related to the approach. Because the maxillary wall opening is very small, infraorbital hypoesthesia is very limited and of short duration.

CONCLUSIONS

Combining the transmaxillary and transnasal approaches for endoscopic management of pterygoid, lateral sphenoid, and retrobulbar orbit lesions provides excellent exposure and avoids the limited working angle and surgical struggle that may be associated with the use of the transnasal approach alone.

Endoscopic sinus surgery: where we are-and where we're going

PURPOSE OF REVIEW

Improved understanding of sinonasal mucociliary function as well as technological advancements have led to a renaissance in the management of sinonasal disease. The current techniques, and adjunctive intraoperative technologies, have allowed for a more precise and safer surgical dissection, extending this surgical application to include the routine endoscopic management of skull base lesions and sinonasal malignancies. The anatomic boundaries of the nasal endoscope continue to be redefined. This paper will review the recent advances in the field of surgical rhinology as well as discuss directions for the future.

RECENT FINDINGS

Advancements in imaging technology including image acquisition, three-dimensional reconstruction, stereotactic navigation, and CT-MRI fusion have aided in more thorough preoperative planning, enabling safer and more precise endoscopic surgical dissection. Refinement of endonasal powered instrumentation including microdebriders and high-speed suction irrigation drills have minimized trauma to normal tissues and accelerated postoperative healing. Increased experience with the endoscope has broadened the endoscopic ventral skull base exposure from the odontoid process to foramen ovale to the olfactory bulb.

SUMMARY

Endoscopic sinus surgery is no longer exclusively for the management of chronic rhinosinusitis and nasal polyposis. Sinonasal malignancies, as well as anterior skull base lesions have become part of the rhinologist's responsibility. Furthermore, selective lesions managed through traditional craniotomies may now be accessed via trans-sinonasal transcranial endoscopic routes.

The effect of maxillary sinus antrostomy size on xenon ventilation in the sheep model

OBJECTIVE

A major goal of maxillary antrostomy is to increase sinus ventilation. Limited data exist regarding the effect of maxillary antrostomy size on sinus ventilation. We sought to quantify the effect of uncinectomy, small antrostomy, and large antrostomy on maxillary sinus ventilation using xenon-enhanced CT in the sheep model. MATERIALS, STUDY DESIGN, AND METHODS: A xenon-oxygen-air mixture was delivered to 8 fresh cadaveric sheep heads while repeated CT scans were performed through the maxillary sinuses. Baseline and postoperative studies were performed after an endoscopic uncinectomy, small antrostomy, or large antrostomy was created. Images were analyzed to measure the density of the xenon gas in the maxillary sinus as a function of time, generating a time constant.

RESULTS

The time constants for both small antrostomy and large antrostomy were significantly different compared to baseline ( P = 0.003 for both). The time constant comparison between small antrostomy and large antrostomy was not significant ( P = 0.948).

CONCLUSIONS

A small antrostomy produces a statistically significant increase in maxillary sinus ventilation over baseline. No significant further ventilation increase is obtained by creating a large antrostomy in the sheep model. This lends credence to the use of small antrostomies to improve maxillary sinus ventilation in human sinus surgery.