Endoscopic access to the infratemporal fossa and skull base: a cadaveric study

Endoscopic Endonasal Supraoptic and Infraoptic Approaches for Complex "Parasuprasellar" Lesions: Surgical Anatomy, Technique Nuances, and Case Series

Objective

The surgical management of lesions involving the lateral area of the suprasellar region, including the lateral aspect of the planum sphenoidale and the tight junction region of the optic canal (OC), anterior clinoid process (ACP), and internal carotid artery (ICA) and its dural rings, is extremely challenging. Here, these regions, namely, the “parasuprasellar” area, are described from the endonasal perspective. Moreover, the authors introduce two novels endoscopic endonasal supraoptic (EESO) and endoscopic endonasal infraoptic (EEIO) approaches to access the parasuprasellar area.

Methods

Surgical simulation of the EESO and EEIO approaches to the parasuprasellar area was conducted in 5 silicon-injected specimens. The same techniques were applied in 12 patients with lesions involving the parasuprasellar area.

Results

The EESO approach provided excellent surgical access to the lateral region of the planum sphenoidale, which corresponds to the orbital gyrus of the frontal lobe. With stepwise bone (OC, optic strut and ACP) removal, dissociation of the ophthalmic artery (OA) and optic nerve (ON), the EEIO approach enables access to the lateral region of the supraclinoidal ICA. These approaches can be used independently or in combination, but are more often employed as a complement to the endoscopic endonasal midline and transcavernous approaches. In clinical application, the EESO and EEIO approaches were successfully performed in 12 patients harboring tumors as well as multiple aneurysms involving the parasuprasellar area. Gross total and subtotal tumor resection were achieved in 9 patients and 1 patient, respectively. For two patients with multiple aneurysms, the lesions were clipped selectively according to location and size. Visual acuity improved in 7 patients, remained stable in 4, and deteriorated in only 1. No postoperative intracranial infection or ICA injury occurred in this series.

Conclusions

The EESO and EEIO approaches offer original treatment options for well-selected lesions involving the parasuprasellar area. They can be combined with the endoscopic endonasal midline and transcavernous approaches to remove extensive pathologies involving the intrasellar, suprasellar, sphenoid, and cavernous sinuses and even the bifurcation of the ICA. This work for the first time pushes the boundary of the endoscopic endonasal approach lateral to the supraclinoidal ICA and ON.

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.

Endoscopic Paramaxillary Approach to the Infratemporal Fossa and Pterygomaxillary Space: Computer Modeling Analysis and Clinical Series

Objective Several different open and endoscopic approaches for the pterygomaxillary space and infratemporal fossa have been described. Limitations to these approaches include restricted exposure of the infratemporal fossa and difficult surgical manipulation.

Study Design Consecutive clinical cases utilizing a novel approach to access lesions in the infratemporal fossa and pterygomaxillary space were reviewed. Data was collected on pathology, lesion location, and surgical approach(es) performed. Computer modeling was performed to analyze the full extent of surgical access provided by the paramaxillary approach to the range of target locations.

Results Ten consecutive cases met inclusion criteria. Surgical access to the target lesion was achieved in all cases. Computer modeling of the approach derived the anatomical boundaries of the paramaxillary approach. Wide access to the posterior maxilla, and lateral or medial to the mandibular condyle allows for variability in endoscopic angles and access to more medial pterygomaxillary space lesions. The lateral extent is limited proximally only by the extent of cheek/soft tissue retraction and by the zygomatic arch more superiorly. The superior limit of dissection is at the temporal line.

Conclusion The endoscopic paramaxillary approach is a transoral minimally disruptive approach to the ITF and PS that provides excellent surgical exposure for resection of lesions involving these areas. Compared with previously described endoscopic approaches, there are no external incisions; tumor manipulation is straightforward without angled endoscopy, and all areas of the infratemporal fossa and pterygomaxillary space can be accessed.

Transoral (transvestibular-paramandibular) endoscopic approach for benign tumours in the infratemporal fossa

We describe a minimally invasive transoral approach to the infratemporal fossa, by means of endoscopy, which facilitates examination and resection of lesions in this area. Furthermore, we outline the technique employed and a case treated with this approach, which permits a rapid access with very low patient morbidity, due to the use of endoscopy and of transoral access, instead of traditional transfacial approaches.

Gain of exposure provided by extended incision in lateral rhinotomy approach: A cadaveric study

OBJECTIVE

To assess the gain of exposure provided by extensions of the lateral rhinotomy (LR) incision, including subciliary extension, lip-splitting extension, or both (Weber-Fergusson incision), by comparing the surgical field obtained with every incision. The final goal is to better delineate the indications of each approach.

MATERIALS AND METHODS

Prospective study on fresh frozen specimens. A LR incision was first performed, and then extended by subciliary and/or lip-splitting incisions. The exposure of the anterior facial skeleton and of the deep retromaxillar spaces (pterygopalatine fossa and infratemporal fossa) were assessed. The distance between the nasal bone and the most lateral part of the exposure was measured.

RESULTS

Dissection was performed on 4 specimens, with 7 LR. Three LR incisions were extended with subciliary incision, 3 with lip-splitting incision, and 4 with Weber-Fergusson incision. LR incision alone gave only limited access to the lateral orbital rim, the zygomatic arch and the maxillary tuberosity. Both subciliary and lip-splitting incisions gave access to the lateral orbital rim and to the zygomatic arch, but only upper lip incision provided a good access to the maxillary tuberosity. Weber-Fergusson did not significantly increase the surgical field obtained with lip-splitting extension alone. The exposure of the deep retromaxillar spaces was the same in all cases.

CONCLUSION

LR incision with lip-splitting extension provided an optimal access to the anterior facial skeleton and to the maxillary tuberosity. In terms of exposure, it was equivalent to Weber-Fergusson approach. The exposure of deep spaces was the same regardless of the incision.

Minimally Invasive Lateral Endoscopic Multiport Approach to the Infratemporal Fossa: A Cadaveric Study

BACKGROUND

Expanded endoscopic endonasal approaches to the infratemporal fossa (ITF) are increasingly performed owing to improved visualization and less morbidity compared with classic open approaches. Only a few studies in the literature investigated lateral endoscopic access to the ITF. The aim of this study was to examine the ITF with the minimally invasive endoscopically assisted Gillies approach with a trial of its expansion through a double port technique.

METHODS

The ITF was examined in 10 sides of 5 cadaveric heads using a lateral endoscopic assisted approach. A double portal technique was developed to allow bimanual dissection. Specific long angled skull base instruments were used for dissection under stereotactic guidance.

RESULTS

The endoscopic assisted Gillies approach permitted minimally invasive access to the complete anteroposterior extension of the ITF with sufficient mobility of surgical instruments. A new anatomic classification for the ITF from a lateral endoscopic perspective was introduced. The addition of the second port allowed bimanual dissection.

CONCLUSIONS

This cadaveric study shows the feasibility of an endoscopically assisted lateral approach to the ITF. The addition of a posterior port expands the approach through increasing the working area and enabling a bimanual dissection technique. Performed alone or combined with an anterior endoscopic transnasal approach, this technique offers minimally invasive access to the ITF. The development of specifically designed instruments would further improve this promising approach.

The endoscopic anatomy of the middle ear approach to the fundus of the internal acoustic canal

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

Endoscopic transmaxillary drainage of an infratemporal fossa abscess

Infratemporal fossa abscess is a rare and challenging condition to diagnose and manage. A few reported cases have been mostly due to odontogenic infections and were managed by external or intraoral drainage. This is the first reported case of an infratemporal fossa abscess that was successfully managed by endoscopic drainage via a transmaxillary approach.

Comparison of surgical freedom and area of exposure in three endoscopic transmaxillary approaches to the anterolateral cranial base

Objective Endoscopic ipsilateral endonasal transmaxillary, contralateral endonasal transseptal transmaxillary, and Caldwell-Luc approaches can access lesions within the retromaxillary space and pterygopalatine fossa. We compared the exposure and surgical freedom of these transmaxillary approaches to assist with surgical decision making. Design Four cadaveric heads were dissected bilaterally using the three approaches just described. Prior to dissection, stereotactic computed tomography (CT) scans were obtained on each head to obtain anatomical measurements. Surgical freedom and area of exposure were determined by stereotaxis. Main Outcome Measures Area of exposure was calculated as the extent of the orbital floor, maxillary sinus floor, nasal floor, and mandibular ramus exposed through each approach. Surgical freedom was the area through which the proximal end of the endoscope could be freely moved while moving the tip of the endoscope to the edges of the exposed area. Results The mean exposed area was similar: 9.9 ± 2.5 cm(2) (Caldwell-Luc), 10.4 ± 2.6 cm(2) (ipsilateral endonasal), and 10.1 ± 2.1 cm(2) (contralateral transseptal) (p > 0.05). The surgical freedom of the Caldwell-Luc approach (113 ± 7 cm(2)) was greater than for either endonasal approach, 76 cm(2 )± 15 (p = 0.001) (ipsilateral endonasal) and 83 cm(2) ± 15 (p = 0.003) contralateral transseptal. Conclusions Our work demonstrates that the Caldwell-Luc endonasal approach offers greater surgical freedom than either approach for anterolateral skull base targets, although these approaches offer similar exposure.

Head and neck fascia and compartments: no space for spaces

An accurate understanding of the arrangement of cervical fascia and its associated compartments is essential for differential diagnosis, predicting the spread of disease, and surgical management. The purpose of this detailed review is to summarize the anatomic, clinical, and radiological literature to determine what is known about the arrangement of cervical fascia and to highlight controversies and consensus. The current terminology used to describe cervical fascia and compartments is replete with confusing synonyms and inconsistencies, creating important interdisciplinary differences in understanding. The term "spaces" is inappropriate. A modified nomenclature underpinned by evidence-based anatomic and radiologic findings is proposed. This should not only enhance our understanding of cervical anatomy but also facilitate clearer interdisciplinary communication.

Evaluating endoscopic and endoscopic-assisted access to the infratemporal fossa: a novel method for assessment and comparison of approaches

OBJECTIVES/HYPOTHESIS

Endoscopic infratemporal fossa (ITF) surgery is a growing clinical interest. This study presents a method of analyzing approach access and visualization, identifies relevant anatomy in an endoscopic approach to the ITF, and compares endoscopic medial maxillectomy (MMA) and endoscopic-assisted sublabial transmaxillary (SLT) approaches to the ITF as a model for this paradigm.

STUDY DESIGN

Human cadaver anatomic study.

METHODS

Five human cadaver heads (10 ITF dissections) were used. An SLT and MMA were performed on each side. For endoscopic dissections of the ITF, 0° and 30° endoscopes were used. Key landmarks were the posterior maxillary sinus wall, temporomandibular joint, pterygoid plates, foramen spinosum, and foramen ovale. Open dissection was used to confirm ITF landmarks. A novel measurement method using angles of approach and visualization was used to compare approaches.

RESULTS

Visualization and mobility in SLT and MMA were significantly different. The lateral extent and greatest average depth for dissection was 7.9 cm in MMA and 6.1 cm for SLT. The average angle of mobility in approach was 36.3° for MMA and 57.9° for SLT. Average visualization was 40.2° for MMA and 126.5° for SLT. Despite these differences, both surgical approaches allowed access and visualization to all targeted landmarks.

CONCLUSIONS

This evaluation paradigm provides useful data in evaluating an endoscopic or endoscopic-assisted approach to the ITF. Using this paradigm, the SLT and MMA were analyzed. Each provided adequate access to the ITF, but visualization and maneuverability were better in SLT.

High-resolution computed tomography analysis of the medial infratemporal fossa: a pilot study

BACKGROUND

The medial aspect of the infratemporal fossa (ITF) can be accessed endoscopically. Two important landmarks to help guide dissection in this area have previously been identified: the anterior border of the foramen ovale (AFO) and the "bony bridge" (BB), a consistent bridge of bone between the foramen ovale and spinosum. We conducted a pilot study using high-resolution computed tomography (HRCT) to measure the distances to these structures.

METHODS

Thirty measurements were acquired from 15 adult patients undergoing HRCT scans of the sinuses. The position of the anterior nasal spine (ANS), AFO, and BB on the 3 orthogonal planes were identified by 3 observers. Euclidian distances between each of these structures were calculated. A cadaveric dissection was performed and images were acquired to provide an endoscopic view.

RESULTS

Fifteen HRCT scans of the sinuses (8 females) were analyzed. The mean distances from the ANS to the AFO and BB were 78.5 ± 5.9 mm and 83.2 ± 6.0 mm, respectively. For males alone, these distances were 80.3 ± 4.3 mm and 85.3 ± 4.8 mm, respectively, and in females 77.0 ± 6.5 mm and 81.4 ± 6.7 mm, respectively.

CONCLUSION

Average distance from the ANS to the AFO and BB was 78.5 mm and 83.2 mm, respectively. These measurements can be used by endoscopic skull base surgeons to guide dissection in the ITF.

Graduated endoscopic multiangle approach for access to the infratemporal fossa: a cadaveric study with clinical correlates

OBJECTIVE

The infratemporal fossa (ITF) has historically been one of the most difficult regions of the skull base to access surgically. Available open approaches are complex, are associated with high morbidity, and do not always afford optimal visualization. Endoscopic access to the ITF improves visualization for management of many sinonasal and lateral skull base lesions involving this region. The purpose of this study is to evaluate a graduated multiangle approach for endoscopic access to this area using a cadaveric model.

STUDY DESIGN AND SETTING

Cadaveric study at an academic medical center.

METHODS

Endoscopic dissection was performed on a total of 10 sides of 5 fresh cadaveric heads. Four different approaches to the ITF were studied: ipsilateral endonasal, endoscopically assisted Caldwell-Luc, contralateral endonasal via septotomy, and endoscopically assisted Gillies transtemporal. High-quality endoscopic pictures and high-definition videos of each technique were obtained in order to document the differences in access achieved with each approach.

RESULTS

The combination of the 4 different endoscopic techniques allowed complete access to all areas of the ITF. The endoscopically assisted Caldwell-Luc improved anteroposterior access, the contralateral septotomy approach resulted in excellent far lateral access, and the endoscopically assisted Gillies approach allowed posterosuperior visualization and instrumentation.

CONCLUSION

Endoscopic access to the ITF can be accomplished by each of the 4 methods described. A multiangle, graduated approach can provide surgeons the ability to customize surgical access depending on the location of a specific lesion within the ITF.

Transnasal endoscopic management of angiofibroma extending to pterygopalatine and infratemporal fossae

Introduction:

Surgical approaches to the pterygopalatine and infratemporal fossae are complex and cause significant morbidity. The commonest benign tumour to extend to the pterygopalatine and infratemporal fossae is angiofibroma.

Patients and methods:

This prospective study included 15 male patients aged 12–27 years with recurrent, severe epistaxis. After computed tomography and magnetic resonance imaging, a modified Wormald and Robinson's two-surgeon approach was used. Follow up, with endoscopy and magnetic resonance imaging, ranged from two to five years.

Results:

Twelve patients were cured (endoscopically and radiologically). Three patients suffered recurrence, one each in the lateral sphenoid wall, pterygoid canal and infratemporal fossa. Revision surgery was performed, but one patient suffered another recurrence (lateral sphenoid wall with cavernous sinus infiltration) and was referred for gamma knife surgery.

Conclusion:

This endoscopic two-surgeon technique is an excellent approach for managing angiofibroma extending to the pterygopalatine and infratemporal fossae. Our modification markedly decreased morbidity by avoiding septum opening and sublabial incision, and by enabling better haemostasis (via maxillary artery control). Recurrence may be minimised by careful examination of the lateral sphenoid wall, pterygoid canal and infratemporal fossa pterygoid muscles.

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.

Endoscopic transnasal study of the infratemporal fossa: a new orientation

INTRODUCTION

The medial portion of the infratemporal fossa (ITF) is not infrequently involved in sinonasal and skull base pathologies. However, endoscopic view of the ITF remains unclear with lack of studies addressing this region from the endoscopic perspective.

METHODS

Using an extended endoscopic approach, the pterygopalatine and infratemporal fossae were dissected in 10 sides of five adult cadaver heads. A plane of dissection along the pterygoid base and the infratemporal surface of the greater sphenoid wing was developed. High-quality images were produced by coupling the video camera to a digital recording system.

RESULTS

The foramen rotundum, ovale, and spinosum were accessed and new landmarks were described from the endoscopic point of view. The sphenomandibularis muscle was also highlighted. Maxillary and mandibular nerves and middle meningeal artery were all identified. Columellar measurements to the foramen rotundum and ovale ranged from 6.1 to 8.0 cm for the former and 7.0 to 9.1 cm for the latter, with a mean of 6.75 cm and 7.78 cm respectively.

CONCLUSION

The current study provides a novel endoscopic orientation to the medial ITF. Such knowledge should provide an anatomical basis for experienced surgeons to endoscopically address this region with more safety and efficacy.

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.

Diagnostic and Surgical Challenges in the Pediatric Skull Base

Advances in management of adult skull base pathologies are increasingly being applied in children. Pediatric patients present special challenges because of their smaller anatomy, but potential gains in reduced morbidity make improvements in skull base approaches well worth pursuing.

Endoscopic Surgery of the Anterior Skull Base

OBJECTIVES/HYPOTHESIS

Traditional surgical approaches to the anterior skull base often involve craniotomy, facial incisions, disruption of skeletal framework, tracheotomy, and an extended hospital stay. As experience with endoscopic sinus surgery has grown, the techniques and equipment have been found to be adaptable to treatment of lesions of the anterior and central skull base. A minimally invasive endoscopic approach theoretically offers the advantages of avoiding facial incisions, osteotomies, and tracheotomy; surgery should be less painful, recovery quicker, and hospital stays should be shorter. The study attempted to assess endoscopic approaches to the anterior and central skull base for its ability to achieve those goals.

STUDY DESIGN

Retrospective review of 72 cases performed at a single institution from November 1996 to July 2003. A subgroup of 15 patients who underwent endoscopic approach to their pituitary tumors was compared with a similar group of 15 patients who underwent traditional open trans-sphenoidal surgery for their pituitary tumors.

METHODS

Patient records were analyzed and information tabulated for age, sex, disease, location of lesion, operative time, use of image-guided surgical systems, blood loss, length of intensive care unit stay, duration of operative pain, length of postoperative hospitalization, complications, and completeness of resection.

RESULTS

Of the cases, 86.1% were performed exclusively endoscopically, and 13.9% used a combination of endoscopic and open techniques. An image-guided surgical system was used in 83% of cases. Hospital length of stay was 2.3 days for the exclusively endoscopic group as opposed to 8 days for the combined group. With the patients with pituitary tumors, operative times were similar between the two groups (255.13 vs. 245.73 min), blood loss was less in the endoscopic group (125.33 vs. 243.33 mL), pain duration was shorter in the endoscopic group (10 of 15 patients pain free on postoperative day 1 vs. 2 of 15 patients pain free in the open group), and intensive care unit stay and hospital length of stay were both shorter in the endoscopic group. Complication rates and completeness of resection was similar in both groups, although the open group had a higher rate of complications related to the approach to the sella.

CONCLUSION

The study demonstrated the safety and efficacy of judicious endoscopic approaches to anterior skull base lesions. An outcomes assessment in pituitary surgery demonstrates advantages of an endoscopic approach in appropriate cases.