A Multiplanar Perspective of Endoscopic Approaches to the Infratemporal Fossa: A Cadaveric Study

Introduction: Various endoscopic approaches to the infratemporal fossa (ITF) have been developed including the transorbital (TOA), endonasal (EEA), and transoral (ETOA) approaches. The objective of this study is to compare the different perspectives of the ITF with each of these approaches and explore the differences in exposure, access, and maneuverability, as well as systematically define areas of optimal access for each approach.

Methods: The ITF was approached through TOA, EEA, and ETOA bilaterally on one latex-injected cadaveric specimen. Optimal dissection planes for each approach were analyzed, as well as access to surgical targets in the ITF, including foramen ovale (FO), temporomandibular joint (TMJ), upper lateral pterygoid plate, and mandibular angle (MA). Depth to surgical targets was measured and surgical freedom (SF) and angles of attack (AoA) were calculated for each approach.

Results: The ITF was divided into three, suprapterygoid, suprapalatal, and infrapalatal. The suprapterygoid ITF is defined as the area superior a horizontal plane drawn across the pterygoid base. The suprapalatal and infrapalatal ITF are superior and inferior to the palatal plane, respectively. TOA provided appropriate access to the suprapterygoid ITF, with a smaller exposure of the ITF than the other approaches. However, it does require relatively less bone work and soft-tissue dissection and has an overall shorter distance to surgical targets, as well as greater AoA and SF, when compared with the EEA and ETOA with the exception of the mandibular angle which was not accessible. The EEA approach was found to be ideal to access to both the suprapalatal and suprapterygoid ITF, providing a wide exposure to a large area of the ITF. The mandibular angle was not accessible through the EEA, as maneuverability is significantly reduced below the palatal plane. ETOA provided the best exposure of the infrapalatal ITF and is the only approach that enabled access to the mandibular angle. Data from at least five additional cadaveric specimens (10 sides) and further statistical analysis of findings will be included to verify and determine the significance of our preliminary findings.

Summary: The ITF was divided into a suprapterygoid, suprapalatal, and infrapatal ITF. Our findings suggest that the TOA provides adequate access to lesions in the supraterygoid ITF and has the greatest SF, AoA, and shortest distance to surgical targets. However, it provides a small exposure and is likely more useful for tumors involving the lateral orbit and tumors with an intracranial component that require middle cranial fossa floor removal which expands the working area. The EEA provides a wide exposure of the suprapterygoid and suprapalatal ITF and allows access to contiguous areas of the skull base on the sagittal plane. ETOA is ideal for approaching lesions in the infrapalatal ITF, and like the EEA, allows dissection to extend medially or laterally as required. Although each approach has its advantages and limitations, it is important to understand that these approaches are not mutually exclusive and can be used adjunctively to address complex lesions involving various areas of the ITF.

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Publication History

Article published online:
12 February 2021