Anthropometric Evaluation of Pterion in Dry Human Skulls Found in Southern India

Abstract

BACKGROUND Pterion is a H-shaped sutural convergence seen in the Norma Lateralis of skull. After 2-3 months of birth, the anterolateral fontanelle in the neonatal skulls close to form the pterion. It is the meeting point of four bones sphenoid, parietal, temporal and frontal. Four types have been noted-spheno-parietal, fronto-temporal, epipteric and stellate. Pterional approach is commonly undertaken in surgical management of tumours involving inferior aspects of frontal lobe, like olfactory meningiomas, orbital, retro-orbital, sellar, chiasmatic, subfrontal, prepontine areas, anterior circulation and basilar artery aneurysm. The knowledge regarding the various shapes and distances from different points to pterion (distance of centre of pterion was calculated from mid-point of superior margin of zygomatic arch (PZA), Frontozygomatic suture (PFZ), tip of the mastoid process (PMP), and anterosuperior margin of external acoustic meatus (PEAM)) is useful for treating number of pathologies in brain. So, this is also useful for neurosurgeons, anatomists, anthropologists and forensic medicine specialists. In the present study, we have attempted to classify the type of pterion and calculated the distance of centre of pterion from various landmarks and compared the measurements on the right and left side. METHODS This study was conducted in the Department of Anatomy, K. S. Hegde Medical Academy, Mangalore. 50 dry human skulls of unknown sex were obtained from the Department of Anatomy and studied. The pterion was observed and classified according to the articulation of bones and the distance of centre of pterion was calculated from mid-point of superior margin of zygomatic arch (PZA), Frontozygomatic suture (PFZ), tip of the mastoid process (PMP), and anterosuperior margin of external acoustic meatus (PEAM). RESULTS The sphenoparietal variety was the commonest (72%) followed by fronto temporal (18 %) and the least common was epipteric (2%). On comparison of measurements of right and left sides, distance of centre of pterion from mid-point of superior margin of zygomatic arch (PZA), Frontozygomatic suture (PFZ), tip of the mastoid process (PMP), and anterosuperior margin of external acoustic meatus (PEAM) did not show any significant difference. CONCLUSIONS Knowledge of position of pterion from various landmarks is very important for neurosurgeons as there is a chance of injury to vital structures present beneath the pterion. The knowledge of position of pterion from various landmarks is very important for neurosurgeons as there is a chance of injury to vital structures present beneath pterion. This study is aimed at South Indian population and can be conducted among other populations.