The Endoscopic Sublabial Anterior Transmaxillary Approach: Middle Meningeal Artery as a Landmark to the Parapharyngeal Internal Carotid Artery

Background: The endoscopic sublabial anterior transmaxillary approach (ESATMA) is a novel application of an established surgical route to access the infratemporal fossa(ITF) and parapharyngeal space (PPS). This study aims to identify the middle meningeal artery (MMA) as a critical anatomical landmark for the localization of the parapharyngeal internal carotid artery (ppICA) within the ESATMA.

Methods: Cadaver dissection of 7 heads (14 sides) was performed via the ESATMA. Additionally, measurements were taken from CTA scans of 20 pituitary adenoma patients (40 sides) to evaluate the relationship between the MMA and ppICA. Furthermore, the step-by-step procedure of the ESATMA to access the ITF and PPS was outlined.

Results: In all 7 cadavers (14 sides), ppICA was found posteromedial to the MMA. The ppICA was located posterior to or posteromedial of the origin point of the MMA from the IMA (MMA-OP), with distances from the ppICA measured at 12.05 mm (6–18) (ruler) and 13.21 mm (7.9–18.3) (neuronavigation confirmation) on the same axial level. The ppICA was located posterior or posteromedial to the cranial entry point of the MMA (MMA-EP) or foramen spinosum (FS), with distances measured at 12 mm (9–15) (ruler) and 11.66 (9.1–14.9) mm (neuronavigation confirmation) on the same axial level. CTA measurements corroborated the cadaveric findings. Additionally, the length of the extracranial segment of the MMA (from MMA-OP to MMA-EP) was ~12.93 mm (cadaveric dissection) and 13.61 mm (neuronavigation confirmation), while the maximum length of exposure of the ppICA achievable through the ESATMA was 26.29 mm (cadaveric dissection) and 26.87 mm (neuronavigation confirmation). Based on cadaveric dissections, we have identified an effective method for localizing the ppICA. This involves locating the internal maxillary artery (IMA) between the temporalis and LPMs, tracing it back to the MMA-oP, and identifying the MMA-EP. Within 1cm posterior to this point, landmarks such as the attachment point of the cartilaginous eustachian tube (ET) and the LVPM (LVPM) to the skull base are sequentially identified. Finally, dissection of the stylopharyngeal fascia (SPF) and carotid sheath (CaSH) reveals the ppICA.

Conclusion: The MMA serves as a novel anatomical landmark for localizing the ppICA within the ESATMA to access the ITF and PPS, providing crucial guidance for surgeons managing tumors or lesions in these regions.

Fig. 1 The MMA as an anterolateral landmark of the ppICA within the ESATMA (left side).

Fig. 2 The MMA serves as the anterolateral landmark for the upper ppICA in CTA images.

Fig. 3 The distances to reach the ppICA using the ESATMA and the endonasal transpterygoid approach.

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Artikel online veröffentlicht:
07. Februar 2025