Endoscopic Endonasal Transrotundum Middle Fossa Exposure: Technique of Transpterygoid Maxillary Nerve Transposition

Extradural anterior temporal fossa approach to the paranasal sinuses, nasal cavities through the anterolateral and anteromedial triangles: Combined microscopic and endoscopic strategy

OBJECTIVE

To demonstrate the utility and limitations of the extradural endoscopic-assisted anterior temporal fossa approach to the pterygopalatine fossa (PPF), infratemporal fossa (ITF), paranasal sinuses (PS), parapharyngeal region (PPR), nasal cavities (NC), epipharynx (EP), and clivus.

METHODS

A frontotemporal orbitozygomatic craniotomy is performed. The dura is elevated from the cavernous sinus (CS). The anterior temporal fossa floor is drilled. Foramen rotundum and ovale are opened. The PPF is exposed and the lateral margin of inferior orbital fissure (IOF) is removed. The anterolateral triangle (ALT) is drilled and the vidian nerve (VN) is exposed. Drilling between the maxillary nerve (V2) and the VN provides access to the sphenoid sinus (SphS). The medial pterygoid plate is drilled exposing the EP. The maxillary sinus (MaxS) is opened anterior to the PPF. V2 is transposed laterally to enlarge the anteriomedial triangle (AMT). The orbital muscle of Muller is removed as well as the medial margin of the IOF, which opens the SphS. Anteriorly, the posterior ethmoid air cells are opened. Morphometric measurements evaluating the size of the ALT were done and the PS, NC, EP were explored with the endoscope.

RESULTS

The ALT and AMT triangle provides a wide exposure of the PPF, ITF, PPR. In addition, those triangles represent a deep entry point to explore the PS, NC, and EP.

CONCLUSION

The ALT and AMT are useful corridors to access to the SphS, MaxS, PS, NC, and EP via a transcranial approach. The use of the endoscope through this corridor widely extend the extradural anterior temporal fossa approach which may be considered as a valuable alternative to the extended endoscopic endonasal approach for selected skull base lesions extending both intracranial and into the PS, NC and EP.

The Anterolateral Triangle: Implications for a Transnasal Prelacrimal Approach to the Floor of the Middle Cranial Fossa

Background

The anterolateral triangle enclosed by the foramen rotundum and foramen ovale constitutes part of the floor of the middle cranial fossa (MCF).

Objective

To assess the feasibility of a transnasal prelacrimal approach for accessing the floor of MCF via an anterolateral triangle corridor and to determine the extent of maximal exposure while safeguarding neurovascular structures.

Methods

A transnasal prelacrimal approach was performed in 5 cadaveric specimens (10 sides). Following the identification of foramen rotundum and foramen ovale, the bony ridge between 2 was drilled to expose the MCF. The temporal lobe dura was then elevated laterally, and the distances from foramen ovale to the respective borders of the area of the MCF window were measured using a surgical navigation device.

Results

The MCF was exposed with a 0° scope in all specimens also exposing significant landmarks including the middle meningeal artery, greater superficial petrosal nerve, superior petrous sinus, and arcuate eminence. Average distances from foramen ovale to the anterior, posterior, and lateral exposed borders were 22.86 ± 1.87 mm, 27.24 ± 0.94 mm, and 24.23 ± 1.61 mm, respectively. The average area of exposed MCF window was 554.12 ± 60.22 mm2. Preservation of vidian nerve, greater palatine nerve, lateral nasal wall, and nasolacrimal duct was possible in all 10 sides.

Conclusion

It is feasible to access the floor of MCF via an endoscopic transnasal prelacrimal approach with seemingly low risk.

Anatomy based corridors to the infratemporal fossa: Implications for endoscopic approaches

Background

The infratemporal fossa (ITF) represents an area densely packed with neurovascular structures within irregular boundaries. The goal of this study was to classify the ITF into zones corresponding to its anatomical spaces and the order in which they are encountered during an endonasal approach (anteroposterior axis).

Methods

Six cadaveric specimens (12 sides) with injected colored latex were dissected. Following an endoscopic medial maxillectomy and Denker's approach, a progressive exploration of the masticator space and upper parapharyngeal space was completed. A classification of the ITF based on well‐defined spaces was ascertained.

Results

The ITF was divided into five zones:

Zone 1 (retromaxillary space)—space lying between the posterolateral wall of the maxillary sinus and the temporalis and pterygoid muscles.

Zone 2 (superior interpterygoid space)—area including the superior head of the lateral pterygoid muscle, V₃, and foramen ovale.

Zone 3 (inferior interpterygoid space)—includes the inferior head of lateral pterygoid muscle, medial pterygoid, and temporalis muscles, and the space enclosed by these muscles.

Zone 4 (temporo‐masseteric space)—space lateral to the temporalis muscle (comprising fat mostly).

Zone 5 (tubopharyngeal space)—includes the Eustachian tube, tensor, and levator veli palatini muscles, and structures in upper parapharyngeal space.

Conclusion

The ITF can be visualized as five zones based on spaces enclosed by the masticator muscles and upper parapharyngeal structures. This novel classification system is useful to guide endoscopic approaches to the ITF, while decreasing the potential for injury of neurovascular structures and pterygoid muscles.

Morbidities Associated with the Endoscopic Transnasal Transpterygoid Approach: Focusing on Postoperative Sequelae

OBJECTIVE

Although the endoscopic transpterygoid approach has been popularized, there are no studies about anatomy-specific morbidities of this approach. The objective of this study is to investigate the surgical morbidities associated with the endoscopic transpterygoid approach for resection of anatomic structures.

METHODS

A retrospective analysis was carried out of prospectively collected data of patients who underwent the endoscopic transpterygoid approach for skull base tumor by a single ear nose and throat surgeon in a tertiary-care center from November 2013 to January 2019. Postoperative patient symptom prevalence associated with surgical findings and SNOT-22 (Sino-Nasal Outcome Test-22) score were included in the analysis.

RESULTS

Thirty-seven consecutive patients were enrolled. The mean follow-up period was 12.4 months (range, 1-39 months). Twenty-six (70.3%) vidian nerves were sacrificed, but only 38.5% of those patients (10/26) reported mild dry eye symptoms. Fourteen nasolacrimal ducts (37.8%) were resected, with only 1 patient (7.1%) who had undergone previous radiation therapy reporting transient epiphora. SNOT-22 scores before and after surgery did not present statistical difference in inferior turbinate sacrifice group and preservation group.

CONCLUSIONS

Sacrifice of sinonasal structures such as the inferior turbinate or vidian nerve is sometimes inevitable for safe tumor resection with the endoscopic transpterygoid approach. Subjective symptoms were not apparent in most patients, despite the structural sacrifice.