Surgical anatomy of the pterion and its relationship to the middle meningeal artery in optimizing pterional craniotomies: a cadaveric perspective.

Abstract

Purpose: The pterion is an anatomic landmark formed via junction of the temporal, sphenoid, parietal, and frontal bones on the lateral aspect of the cranium. Due to the proximity to the middle meningeal artery (MMA), pterion-based surgical approaches have a potential risk of arterial rupture, leading to subsequent epidural hematoma formation. This study characterized the localization of the pterion and its relationship to the MMA in the four main pterion configurations.

Methods: Ninety-one pterions were exposed, and suture patterns were uncovered to determine pterion classification. Dura mater was removed to expose the groove for the MMA and relationship to the pterion, documenting the presence or absence of a bony bridge. Skull thickness at the pterion center was collected for each specimen.

Results: Sphenoparietal (Type I) pterions were present in 67.03%, Frontotemporal (Type II) in 10.99%, Stellate (Type III) in 16.48%, and Epipteric (Type IV) in 5.49% of specimens, with non-identical pterion types located bilaterally in 47.62%. A significant difference was found in five of the eight measurements obtained between male and female cadavers, including the distance to the frontozygomatic suture (FZMS). The distance between pterion center and the groove for the MMA, as well as skull thickness, also demonstrated statistical significance, with the smallest distance and skull thickness demonstrated in Type III pterions.

Conclusion: Type I is the most prevalent pterion configuration, with Type III most closely situated to the course of the MMA. This study demonstrates the importance of determining pterion type pre-operatively to ensure vascular preservation of MMA.