Surgical anatomy and nuances of the expanded transpterygoid approach to the pterygopalatine fossa and upper parapharyngeal space: a stepwise cadaveric dissection

Endoscopic Endonasal Transpterygoid Approach and the Need for Myringotomy

OBJECTIVE

The expanded endonasal transpterygoid approach (EETA) is used to access the middle and posterior fossa through the pterygoid process. Traditionally, the eustachian tube (ET) was resected during EETA, which often required subsequent myringotomy for inner ear drainage. Anterolateral transposition of the ET was proposed to decrease potential morbidity associated with resection. However, a comparison of resection versus transposition regarding the need for subsequent myringotomy has not been reported.

METHODS

This is a retrospective cohort study of patients who underwent an EETA. Patient demographics, tumor characteristics, management of ET with resection versus transposition, and need for subsequent myringotomy were collected. Analysis was performed with JMP software in standard fashion and univariate and multivariate logistic regression analysis performed with a p < 0.05 was considered significant.

RESULTS

Ninety-one patients underwent EETA for various malignant and benign tumors. Twenty-seven patients required myringotomy, with tumors of the pterygopalatine fossa accounting for the most common location (n = 8). Malignant pathology had the highest myringotomy rate compared to benign tumors (48.9% vs. 10.9%, p < 0.001), as did receiving postoperative radiation (p < 0.001), ET resection (p < 0.001), and increasing CPK class. Multivariate analysis of these variables suggests that only ET resection significantly correlated with the need for myringotomy (LR 7.97, p = 0.005).

CONCLUSIONS

ET resection during EETA can lead to ET dysfunction and require myringotomy post-operatively, and patients should be counseled of this risk. Radiation treatment, malignant pathology, and CPK class, all reflecting situations where more extensive surgery was needed, were associated with the need for myringotomy on univariate analysis but did not reach significance with multivariate analysis.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:1203-1207, 2024.

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Endoscopic Endonasal and Endoscopic-Assisted Transmaxillary Transpterygoid Approaches

Introduction  The endoscopic endonasal transpterygoid approach (EETPA) with or without the addition of the endoscopic-assisted sublabial anterior transmaxillary approach (ESTA) has become increasingly utilized for lesions posterior to the pterygopalatine fossa (PPF), including infratemporal fossa (ITF), lateral recess of the sphenoid sinus, Meckel's cave, petrous apex, and parapharyngeal space. The main goal of this study is to develop an educational resource to learn the steps of the EETPA for trainees. Methods  EETPA and ESTA were performed in 12 specimens by neurosurgery trainees, under supervision from the senior authors. One EETPA and one ESTA were performed on each specimen on opposite sides. Dissections were supplemented with representative cases. Results  After a wide unilateral sphenoidotomy, ethmoidectomy, and partial medial maxillectomy, the anteromedial bone limits of the PPF were identified and drilled out. The pterygoid progress was modularly removed. By enlarging the opening of the posterior and lateral walls of the maxillary sinus through EETPA and ESTA, respectively, the neurovascular and muscular compartments of the PPF and ITF were better identified. The EETPA opens direct corridors to the PPF, medial ITF, middle cranial fossa, cavernous sinus, Meckel's cave, petrous apex, and internal carotid artery. If a more lateral exposure of the ITF is needed, the ESTA is an appropriate addition. Conclusion  Despite the steep learning curve of the EETPA, granular knowledge of its surgical anatomy and basic surgical steps are vital for those advancing their learning in complex endoscopic approaches to the ventral skull base when expanding the approach laterally in the coronal plane.

Endoscopic endonasal transpterygoid nasopharyngectomy: Anatomical considerations and technical note

BACKGROUND

The study was designed to identify new landmarks in the parapharyngeal segment of the internal carotid artery (ICA) for nasopharyngectomy and describe a surgical procedure of endoscopic endonasal transpterygoid nasopharyngectomy (EETPN).

METHODS

Four cadaveric specimens were injected with colored silicone and subjected to CT scanning before dissection. The nasopharyngeal skull base was exposed using the endoscopic endonasal transpterygoid approach. The clinical data of four patients with nasopharyngeal malignances who underwent EETPN were reviewed.

RESULTS

The lateral edge of the longus capitis muscle medially; the foramen lacerum, petrous apex spine and the stump of the levator veli palatini muscle superior laterally; and the upper parapharyngeal ICA laterally constitute the ICA-longus capitis muscle-petrous apex spine triangle which was a novel landmark for the upper parapharyngeal segment of the ICA.

CONCLUSION

The ICA-longus capitis muscle-petrous apex spine triangle are important landmarks of the upper parapharyngeal segment of the ICA.

Defining the limits of the anterior wall of the cavernous sinus through an endoscopic view: Cadaveric anatomical study

BACKGROUND

The anterior wall of the cavernous sinus (CS) represents an important landmark for endoscopic surgery that although mentioned before, no precise anatomical boundaries have been described. We describe the anatomical landmarks that delimit the anterior wall of the CS, emphasizing its importance as a reference for accessing the CS through endoscopic approaches.

METHODS

Six adult cadaveric heads fixed with formaldehyde and injected with colored silicone were studied. In all the heads, an endonasal endoscopic approach to the sellar and parasellar regions was performed and the anatomy of the anterior wall of the CS was studied.

RESULTS

Four consistent anatomical landmarks that mark the limits of the anterior wall of the CS were found in all the specimens: anterosuperiorly, the lateral opticocarotid recess; posterosuperiorly, the medial opticocarotid recess; anteroinferiorly, the inferior part of the maxillary strut; and posteroinferiorly, the superolateral angle of the clival recess.

CONCLUSION

It is of paramount importance to recognize the anatomical landmarks that define the limits of the anterior wall of the CS to achieve a safe access to this so complex region.

Classification of Endoscopic Transnasal Lateral Skull Base Approaches: Anatomical Study

OBJECTIVE

Endoscopic transnasal approaches (ETAs) to the ventrolateral skull base are commonly classified according to coronal planes or anatomical structures. Our goal is to simplify the description of the ETA to lateral skull base regions in a sequential dissection with correlation to computed tomography, helping in preoperative planning and efficient surgical exposure, and exposing the surgical anatomy limitations.

METHODS

Five freshly injected cadaver heads were dissected using an extended ETA to the lateral skull base. Each specimen underwent a high-resolution computed tomography scan. A classification of the lateral skull base based on well-defined zones was proposed.

RESULTS

We divided the lateral target into four different zones, in a craniocaudal orientation: zone 1 is the space lying between the orbital floor superior and the level of the sellar floor inferior, zone 2 is on the coronal plane, located between the level of the sellar floor and the vidian canal, zone 3 is the area lateral to the anterior limb of the petro-occipital fissure, located between the vidian canal and the carotid canal, and zone 4 is the space located between the carotid canal and the extracranial opening of the hypoglossal canal, lateral to the anterior part of the posterior limb of petro-occipital fissure.

CONCLUSIONS

Multiple previous works have described and classified the coronal plane and its lateral extensions. Our classification system for the proposed lateral zones enables preoperative planning to select a suitable approach. The craniocaudal orientation facilitates the understanding of surgical corridors and tailored exposure.

Endoscopic transoral approach to the lateral poststyloid space

The lateral poststyloid space (LPSS) located at the posterolateral aspect of the styloid process. This study aims to explore the anatomical relationships in LPSS via a transoral corridor, providing reference for addressing lesions extending to this region. An endoscopic transoral approach for exposure of the LPSS was performed on 6 cadaveric specimens (12 sides). Related landmarks were explored, and transoral extirpation of tumors extended into LPSS was employed in 12 patients. The deep lobe of the parotid gland, extratemporal facial nerve, and the accompanying artery in the LPSS were sufficiently exposed via the transoral corridor in all 12 cadaveric sides. The transoral corridor provided adequate exposure for tumors extending to the LPSS, and en bloc resection was achieved in these 12 patients. No facial nerve or vascular injury occurred, and no recurrence observed in this cohort with an average follow-up of 26 months. An endoscopic transoral approach provides a direct access to the LPSS. Appreciation of the anatomical relationships within the LPSS is valuable for employing a transoral extirpation of tumors extending to this specific region.

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.

Combined biportal unilateral endoscopic endonasal and endoscopic anterior transmaxillary approach for resection of lesions involving the infratemporal fossa

BACKGROUND

Approaching tumors involving the infratemporal fossa (ITF) is technically challenging due to the complex relationships between several neurovascular structures and the deep-seated location of these lesions.

METHODS

The authors describe in detail a minimally invasive approach to the ITF, consisting on a single-nostril endoscopic endonasal transmaxillary approach aided by an anterior transmaxillary port (EEA-ATMa). Anatomical landmarks and surgical tenets of this approach are highlighted and reviewed with the goal to guarantee successful tumor resection and avoid operative complications.

CONCLUSION

The EEA-ATMa is technically feasible and offers excellent surgical exposure to the anterior and lateral aspect of ITF, without the need of transecting the Vidian nerve or performing a wide septectomy.

Techniques and challenges of the expanded endoscopic endonasal sellar and parasellar approaches to invasive pituitary tumors

BACKGROUND

Superb knowledge of surgical anatomy and nuances to remove the natural barriers preventing full access to the paramedian skull base determines the ease of using the expanded sellar/parasellar approaches as the main gateway for all the parasagittal modules during endoscopic endonasal access (EEA) to pituitary tumors with cavernous sinus (CS) invasion.

METHODS

Throughout stepwise-cadaveric dissections and pertinent intraoperative analysis, we describe surgical pearls and pitfalls of the parasellar-EEA with special references to the utility of various lines/classifications on neuroimaging correlated with strategies to enhance surgical safety and tumor resection.

CONCLUSION

EEA to invasive parasellar pathologies needs to address strict bleeding control and displacement of neurovascular structures inside the CS, posing a chance for neurologic morbidities/ICA injury. Meticulous utilization of operative landmarks and strategies can help avoid and mitigate surgical complications.

Endoscopic approaches to skull base malignancies affecting the anterior fossa

Anterior skull base malignancies are rare and comprise distinct histological entities. Surgery encompasses the traditional craniofacial resections (CFR), and more recently, endoscopic endonasal approaches (EEA) or a hybrid cranioendoscopic (CEA) technique. Although the CFR is still considered the "gold-standard;" there is growing evidence supporting that EEA yield equivalent oncologic outcomes with less morbidity in well-selected cases. Therefore, this article aims to review the current state-of-art in addressing anterior cranial base malignancies using expanded endoscopic endonasal approaches (EEA) with particular references to surgical anatomy and nuances of hybrid cranioendoscopic techniques. Cadaveric dissections and illustrative cases are presented to detail our current surgical technique allied with tailored adjuvant therapies, and treatment strategies are further discussed based on tumor histology.