Jason Van Rompaey

Access to the parapharyngeal space: an anatomical study comparing the endoscopic and open approaches.

A subtemporal preauricular approach to the infratemporal fossa and parapharyngeal space has been the traditional path to tumors of this region. The morbidity associated with this procedure has lead to the pursuit of less invasive techniques. Endoscopic access using a minimally invasive transmaxillary/transpterygoid approach potentially may obviate the drawbacks associated with open surgery. The anatomy of the parapharyngeal space is complex and critical; therefore, a comparison of the anatomy exposed by these different approaches could aid in the decision making toward a minimally invasive surgical corridor.

Landmarks for endoscopic approach to the parapharyngeal internal carotid artery: A radiographic and cadaveric study

To define transnasal endoscopic surgical landmarks for the parapharyngeal segment of the internal carotid artery (ppICA) using radiographic analysis and cadaveric dissection.

Endoscopic repair of an injured internal carotid artery utilizing femoral endovascular closure devices

Injury to the internal carotid artery is a feared complication of endoscopic endonasal surgery of the skull base. Such an event, although rare, is associated with high morbidity and mortality. Even if bleeding is controlled, permanent neurological defects frequently persist. Many techniques have been developed to manage internal carotid artery rupture with varying degrees of success. The purpose of this study was to explore endoscopic management of arterial damage with endovascular closure devices used for a femoral arteriotomy. The ability to remotely suture a damaged artery permits the possible adaptation of this technology in managing endoscopic arterial complications.

Meckel's cave access: anatomic study comparing the endoscopic transantral and endonasal approaches.

Recent advances in endonasal endoscopy have facilitated the surgical access to the lateral skull base including areas such as Meckel’s cave. This approach has been well documented, however, few studies have outlined transantral specific access to Meckel’s. A transantral approach provides a direct pathway to this region obviating the need for extensive endonasal and transsphenoidal resection. Our aim in this study is to compare the anatomical perspectives obtained in endonasal and transantral approaches. We prepared 14 cadaveric specimens with intravascular injections of colored latex. Eight cadavers underwent endoscopic endonasal transpterygoid approaches to Meckel’s cave. Six additional specimens underwent an endoscopic transantral approach to the same region. Photographic evidence was obtained for review. 30 CT scans were analyzed to measure comparative distances to Meckel’s cave for both approaches. The endoscopic approaches provided a direct access to the anterior and inferior portions of Meckel’s cave. However, the transantral approach required shorter instrumentation, and did not require clearing of the endonasal corridor. This approach gave an anterior view of Meckel’s cave making posterior dissection more difficult. A transantral approach to Meckel’s cave provides access similar to the endonasal approach with minimal invasiveness. Some of the morbidity associated with extensive endonasal resection could possibly be avoided. Better understanding of the complex skull base anatomy, from different perspectives, helps to improve current endoscopic skull base surgery and to develop new alternatives, consequently, leading to improvements in safety and efficacy.

Minimally invasive access to the posterior cranial fossa: An anatomical study comparing a retrosigmoidal endoscopic approach to a microscopic approach

OBJECTIVES The central location and complex neurovascular structures of the posterior cranial fossa make tumor resection in this region challenging. The traditional surgical approach is a suboccipital craniotomy using a microscope for visualization. This approach necessitates a large surgical window and cerebellar retraction, which can result in patient morbidity. With the advances in endoscopic technology, minimally invasive access to the cerebellopontine angle can be achieved with minimal manipulation of uninvolved structures, reducing the complications associated with the suboccipital approach. METHODS An endoscopic and microscopic approach was completed on anatomic specimens. To access the central structures of the posterior cranial fossa, a retrosigmoidal approach was undertaken. A keyhole craniotomy was made in the occipital bone posterior to the junction of the transverse and sigmoid sinuses. The endoscope was advanced and photographs were obtained for review. The exposure was compared with that obtained with a microscope. RESULTS The endoscopic retrosigmoidal approach to the posterior cranial fossa provided increased exposure to the midline structures while minimizing the surgical window. The relevant anatomy was identified without difficulty. CONCLUSION An endoscopic retrosigmoidal approach to the midline structures of the posterior cranial fossa is anatomically feasible. The morbidity associated with retraction of the cerebellum could possibly be avoided, improving patient outcomes. Retrosigmoidal endoscopy provides access to anatomical structures that is not possible using a microscope in a suboccipital approach. Further understanding of the endoscopic anatomy of the posterior fossa can allow for advances in cranial base surgery with improved safety and efficacy.

Anatomical and computed tomographic analysis of the transcochlear and endoscopic transclival approaches to the petroclival region.

Advances in the field of skull base surgery aim to maximize anatomical exposure while minimizing patient morbidity. The petroclival region of the skull base presents numerous challenges for surgical access due to the complex anatomy. The transcochlear approach to the region provides adequate access; however, the resection involved sacrifices hearing and results in at least a grade 3 facial palsy. An endoscopic endonasal approach could potentially avoid negative patient outcomes while providing a desirable surgical window in a select patient population.

Anatomic analysis specific for the endoscopic approach to the inferior, medial and lateral orbit

Abstract Introduction: The endoscopic approaches to the medial and inferior orbital walls have continued to grow in popularity. The ability to provide a safe approach to the orbit through this technique has been described in a handful of studies. Even though metric analyses have been conducted on orbital anatomy, few have outlined the anatomical relations pertinent to endoscopic surgery. The goal is to provide improved understanding of the complex anatomy encountered through anatomical dissections and metric analysis of the orbit. This information could assist in approach selection during preoperative planning. Methods: Anatomical dissections via transantral and endonasal approaches were used to define the limits with current endoscopic sinus surgery instrumentation. The surface area was then calculated of the floor and medial wall to assess access created by the approaches. The path of the infraorbital canal was conducted to assess its placement within the orbital floor. Results: The transantral and endonasal approaches to the orbit provided an adequate surgical window inferiorly and medially. This was confirmed by the surface area calculations. Access laterally was also possible, however, it became limited as dissection advanced superior to the lateral rectus muscle. The infraorbital canal was located consistently at midline on the orbital floor. Conclusion: Endoscopic access to the medial and inferior parts of the orbit is feasible and creates adequate access with current instrumentation. Knowing the surgical boundaries and the amount of exposure created can assist the surgeon in deciding a minimally invasive approach.

What is the Best Route to the Meckel Cave? Anatomical Comparison between the Endoscopic Endonasal Approach and a Lateral Approach

Background Traditionally, a pterional approach is utilized to access the Meckel cave. Depending on the tumor location, extradural dissection of the Gasserian ganglion can be performed. An endoscopic endonasal access could potentially avoid a craniotomy in these cases. Methods We performed an endoscopic endonasal approach as well as a lateral approach to the Meckel cave on six anatomic specimens. To access the Meckel cave endoscopically, a complete sphenoethmoidectomy and maxillary antrostomy followed by a transpterygoid approach was performed. For lateral access, a pterional craniotomy with extradural dissection was performed. Results The endoscopic endonasal approach allowed adequate access to the Gasserian ganglion. All the relevant anatomy was identified without difficulty. Both approaches allowed for a similar exposure, but the endonasal approach avoided brain retraction and improved anteromedial exposure of the Gasserian ganglion. The lateral approach provided improved access posterolaterally and to the superior portion. Conclusion The endoscopic endonasal approach to the Meckel cave is anatomically feasible. The morbidity associated with brain retraction from the open approaches can be avoided. Further understanding of the endoscopic anatomy within this region can facilitate continued advancement in endoscopic endonasal surgery and improvement in the safety and efficacy of these procedures.

Clinical Correlates of the Anatomical Relationships of the Foramen Ovale: A Radioanatomical Study

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

Transantral Approach to the Lateral Orbit

Objective: Depending on the type of pathology and location, various methods of access have been developed to overcome the obstacle of accessing the orbit. The endoscope provides minimally invasive surgical access to the medial and inferior orbit. Expanding endoscopic access to the lateral orbit transantrally could create a minimally invasive corridor. Method: Using late injected cadavers, endoscopic dissections of the infero-lateral orbit were undertaken. A sublabial transmaxillary ostomy was created and an endoscope was advanced into the sinus. The contents of the orbit were dissected laterally to the inferior optic nerve. Photographic evidence was obtained for review. Results: A 45° endoscope was required to adequately visualize the anatomy. The perpendicular nature of the corridor necessitated the use of angled instrumentation. This also created a challenge as the dissections were completed superiorly. Dissection was found to be facile until revealing the lateral rectus muscle. Proceeding superiorly past this point was limited by the length of the instruments. Tools of dissection with greater length could possibly overcome this limitation. Overall the transantral endoscopic approach to the orbit provided an adequate surgical window inferiorly and to a limited extent laterally. The relevant anatomy was identified without difficulty. Conclusion: An endoscopic transantral approach to the infero-lateral orbit is anatomically feasible. The morbidity associated with an open approach could possibly be avoided, improving patient outcomes. Further understanding of the endoscopic anatomy of the orbit can allow for advances in surgery with improved safety and efficacy.