Approaches to Parapharyngeal Space and Infratemporal Fossa Based on Different Anatomical Spaces

The parapharyngeal space (PPS) and infratemporal fossa (ITF) present significant challenges for endoscopic skull base surgery due to their complex anatomy and lack of clear bony landmarks. This study aims to propose a systematic compartmentalization of the PPS and ITF, based on key anatomical structures, to optimize surgical planning and approaches.

To retain a precise bony reference framework, the walls of the maxillary sinus and pterygoid bone were preserved. Anatomical dissection was conducted along muscular planes, dividing the region into 3 spaces. The feasibility and applicability of the proposed compartmentalization were evaluated through cadaveric studies and verified in clinical cases.

The PPS and ITF were classified into 3 distinct spaces based on the positioning and orientation of the medial pterygoid, lateral pterygoid, levator veli palatini, and stylopharyngeus muscles. The first space is located anterior to the pterygoid muscles, the second lies between the pterygoid muscles and the levator veli palatini/stylopharyngeus, and the third is posterior to these latter muscles. Among 24 clinical cases reviewed, 3, 8, and 13 lesions were situated in the first, second, and third spaces, respectively. Surgical outcomes were favorable, with complete lesion resection and no intraoperative or postoperative complications observed.

A three-space model of the PPS and ITF, defined by specific muscle planes, provides a structured framework to guide endoscopic skull base approaches. This model allows for targeted selection of surgical routes based on lesion location and its relationship with the internal carotid artery, aiming to minimize procedural risks.