Anatomical Variations and Relationships of the Infratemporal Fossa: Foundation of a Novel Endonasal Approach to the Foramen Ovale

Abstract

Objective Access to the infratemporal fossa (ITF) is complicated by its complex neurovascular relationships. In addition, copious bleeding from the pterygoid plexus adds to surgical challenge. This study aims to detail the anatomical relationships among the internal maxillary artery (IMA), pterygoid plexus, V3, and pterygoid muscles in ITF. Furthermore, it introduces a novel approach that displaces the lateral pterygoid plate (LPP) to access the foramen ovale. Design and Main Outcome Measures Six cadaveric specimens (12 sides) were dissected using an endonasal approach to the ITF modified by releasing and displacing the LPP and lateral pterygoid muscle (LPTM) as a unit. Subperiosteal elevation of the superior head of LPTM revealed the foramen ovale. The anatomic relationships among the V3, pterygoid muscles, pterygoid plexus, and IMA were surveyed. Results In 9/12 sides (75%), the proximal IMA ran between the temporalis and the LPTM, whereas in 3/12 sides (25%), the IMA pierced the LPTM. The deep temporal nerve was a consistent landmark to separate the superior and inferior heads of LPTM. An endonasal approach displacing the LPP in combination with a subperiosteal elevation of the superior head of LPTM provided access to the posterior trunk of V3 and foramen ovale while sparing injury of the LPTM and exposing the pterygoid plexus. The anterior trunk of V3 traveled anterolaterally along the greater wing of sphenoid in all specimens. Conclusion Displacement of the LPP and LPTM provided direct exposure of foramen ovale and V3 avoiding dissection of the muscle and pterygoid plexus; thus, this maneuver may prevent intraoperative bleeding and postoperative trismus.

Exploration of anatomical landmarks for performing an endoscopic transoral nasopharyngectomy

“…However, copious bleeding from the pterygoid plexus during separation or transection of the tensor or levator veli palatini muscle may be encountered in the clinical scenario; and as such, preparations for achieving hemostasis are necessary. 27 The pICA is the most import structure to be recognized and preserved for procedures with respect to nasopharyngeal malignancies infiltrating laterally into the parapharyngeal space. 28 Given that the average distance from the junction between the cartilaginous and bony Eustachian tube to the pICA was 4.3 mm, it still carries great risks to perform a nasopharyngectomy prior to identification and preservation of the pICA via an endonasal corridor.…”

“…Furthermore, transection of the Eustachian tube and the levator veli palatini muscle together at the level of petrotympanic fissure toward a medial direction reduces the risk of injury to the pICA, which may also provide the possibility for removal of a recurrent nasopharyngeal malignancy en bloc . However, copious bleeding from the pterygoid plexus during separation or transection of the tensor or levator veli palatini muscle may be encountered in the clinical scenario; and as such, preparations for achieving hemostasis are necessary 27 …”

Endonasal access to the lateral poststyloid space: Far lateral extension of an endoscopic endonasal corridor

“…Expanded endonasal approaches (EEA) to the skull base have undergone sustained advancements, providing the advantage of avoiding brain retraction. [1][2][3] The cavernous sinus, anteromedial aspect of the Meckel's cave, petrosal apex, petroclival region, and ventral aspect of the brainstem can all be accessed directly through an EEA corridor. [4][5][6] Furthermore, an EEA can also avoid external incisions and are associated with a shortened stay in the hospital, superior postoperative quality of life, and satisfactory surgical outcomes.…”

“…Expanded endonasal approaches (EEA) to the skull base have undergone sustained advancements, providing the advantage of avoiding brain retraction 1–3 . The cavernous sinus, anteromedial aspect of the Meckel's cave, petrosal apex, petroclival region, and ventral aspect of the brainstem can all be accessed directly through an EEA corridor 4–6 .…”